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University of Khartoum Graduate College Medical and Health Studies Board ORTHODONTIC STATUS AND TREATMENT NEED OF 12YEAR-OLD CHILDREN IN YEMEN: AN EPIDEMIOLOGICAL STUDY USING THE DENTAL AESTHETIC INDEX By Nabil Muhsen Mohammed Al-Zubair B.D.S. (Jordan) 1996, M.Sc. (Orthodontic) (Iraq) 2002 A thesis submitted in fulfillment of the requirement for the Degree of Doctor of Philosophy in Orthodontic Dentistry July 2006 Supervisor Prof. Ibrahim A. Ghandour B.D.S. (Khartoum), M.Sc. (London) DDPH, Rcs, (England) U of K Table of Contents Dedication I Acknowledgment II Abbreviations III Abstract IV Abstract Arabic VII List of figures IX List of Tables X Chapter One Introduction & Literature Review (1-56) Chapter Two Material and Methods (57-72) Chapter Three Results (73-131) Chapter Four Discussion (132-168) Conclusion 169 Recommendations 172 References Appendices (174-206) 207 Dedication To My Beloved Family. To All People Who Love Me. To All The People I Love. Acknowledgment Thanks to ((Allah)) throughout the whole of my life and for inspiring me with energy and strength to finish this work. My deepest gratitude and appreciation go to my supervisor Prof. Ibrahim A. Ghandour for his patience and very helpful comments, his bright ideas, guidance and for being generous with his knowledge and experience and time in supervising this work. My great thanks and gratitude to the Dean of College of Dentistry, Khartoum University, Prof. Ahmed Suleiman for his efforts in providing me with all guidance, scientific support and continuous follow up. Also my great thanks go to Sana’a University and College of Dentistry for giving me this opportunity and support to continue my study. Appreciation and thanks go to Prof. Kamal Abas, Dr. Amal AbuAffan, Dr. Mohammed Abuelgasim and Dr.Fadyl El-Amin for their great support during my study. Special appreciation goes to Prof. Yahia Al-Taib and Dr. Nadia Yahia for their great generosity, particularly their kind gentile cooperation and support during my study. Finally, I would like to acknowledge, with deep gratitude, my family, wife and kids for their continuous support, encouragement and help throughout the study. List of abbreviations ANOVA analysis of variance DAI Dental Aesthetic Index df degree of freedom F Fisher's exact test FDI Federation Dentaire lnternationale n number NS Statically not significant PAR Peer Assessment Rating SPSS Statistical Package for the Social Sciences Std. error Standard error of mean WHO World Health Organization x2 Chi-square Abstract The aim of this study was to evaluate the prevalence and severity of malocclusion and orthodontic treatment need in a sample of 12-year-old Yemeni school children using the Dental Aesthetic Index (DAI), and to assess the relationship between malocclusion and certain socio-demographic variables. The sample comprised 3127, 12-year-old children attending schools in six governorates (cities and environs) in Yemen. For each subject the standard demographic information such as gender, location type and employment status of the parents were collected, after which a questionnaire was used to determine the perception of occlusion and orthodontic demand of the children and an intra-oral examination for occlusal status using the DAI was performed as recommended by the World health Organization(WHO). The results showed that 63.4% of the children in the sample presented with good or minor malocclusion, just over 36.6 % presented with identifiable malocclusion, i.e. a DAI score larger than 26. Of these, 17.7% had definite malocclusion, 13.0% had severe malocclusion and 6.0% had very severe or handicapping malocclusion. Malocclusion as defined in this study was found to be significantly associated with the different governorates in Yemen, gender and dentition stage, but not with the degree of urbanization setting (urban Vs rural), or the employment status of parents. The results of the individual variables showed that anterior maxillary and mandibular irregularity occurred in more than 40% of the sample. More than 31% of the children examined showed signs of crowding. Spacing in the incisal segments occurred in almost 24% of the sample and maxillary midline diastema was present in 14.2%. A maxillary midline diastema, larger than 2mm, was more prevalent in 12-year-old females than in males. Thirty two per cent of the sample had an increased overjet larger than 3mm and a severe overjet of 6mm or more occurred in only 2.0% of the sample. Mandibular overjet affected only 10.7% and was more prevalent in the late mixed dentition stage than in the early permanent dentition stage. Anterior openbite occurred in 8.3% of the sample and ranged from 1mm to 5mm. Almost 31% of the sample had an antero-posterior molar relation discrepancy. The results of this study indicated a high prevalence of malocclusion in 12-year-old Yemeni children. The findings provide reliable base-line data regarding the prevalence, distribution and severity of malocclusion as well as useful epidemiological data on the orthodontic treatment needs of 12-year-old children in selected rural and urban areas in Yemen. The inclusion of occlusal traits as part of the index provided an opportunity to assess several occlusal characteristics in 12-year-old Yemeni children, separately. Taking the results of the present study as an estimate, it could be estimated that about 25,300 children aged 12 years must be urgently treated every malocclusion, in all of Yemen. year to control handicapping In conclusion, the need for orthodontic treatment in Yemen is less than that in western countries but the demand for treatment was remarkably low, stressing on the role of dental health education to encourage the children and their families to seek orthodontic treatment. ﻤﻠﺨﺹ ﺍﻷﻁﺭﻭﺤﺔ ﻫﺩﻓﺕ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴ ِﺔ ﺇﻟﻰ ﺘﻘﻴﻴﻡ ﺍﻨﺘﺸﺎ ﺭ ﻭﺸ ﺩ ﹶﺓ ﺴﻭﺀ ﺍﻹﻁﺒﺎﻕ ﻭﺍﻟﺤﺎﺠـﺔ ﺇﻟـﻰ ﺍﻟﻤﻌﺎﻟﺠـ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ﻓﻲ ﺍﻟﻴﻤﻥ ﻓﻴﻤﺎ ﻴﺘﻌﻠﻕ ﺒﺎﻟﺠﻨﺱ,ﻭﻤﻘﺭ ﺍﻟﺴﻜﻥ )ﺭﻴﻑ ﺍﻡ ﺤﻀﺭ( ﻭﺍﻟﺤﺎﻟﺔ ﺍﻟﻭﻅﻴﻔﻴﺔ ﻟﻸﺒﺎ ِﺀ. ﺕ ﻴﻤﻨﻴﺔ )ﺭﻴﻑ ﻭ ﺤﻀﺭ( ,ﻭﻀﻤﺕ ﺍﻟﻌﻴﻨﺔ 3127ﻁﻔـل ﺕ ﻤﺤﺎﻓﻅﺎ ِ ﺕ ﺍﻟﺩﺭﺍﺴ ِﺔ ﺴ ﹼ ﺸﹶﻤﻠ ﹾ ﻴﻤﻨﻲ ﻤﻥ ﻁﻼﺏ ﺍﻟﻤﺩﺍﺭﺱ ﺍﻻﺒﺘﺩﺍﺌﻴﺔ ﺒﻌﻤﺭ 12ﺴﻨﺔ. ﺸﻤل ﺍﻟﺒﺤﺙ ﺍﺴﺘﻤﺎﺭﺓ ﺇﺴﺘﺒﻴﺎﻨﻴﺔ ﻟﻤﻌﺭﻓﺔ ﺇﺩﺭﺍﻙ ﺍﻟﻁﺎﻟﺏ ﻹﻁﺒﺎﻗﻪ ﻭﺍﻟﻁﻠﺏ ﻋﻠﻰ ﺍﻟﻤﻌﺎﻟﺠـ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ,ﻭﻓﺤﺹ ﺴﺭﻴﺭﻱ ﻟﻤﻌﺭﻓﺔ ﺍﻨﺘﺸﺎ ﺭ ﺴﻭﺀ ﺍﻹﻁﺒﺎﻕ ﻭﺍﻟﺤﺎﺠﺔ ﺇﻟـﻰ ﺍﻟﻤﻌﺎﻟﺠـ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴـﺔ ﺍﻋﺘﻤﺎﺩﺍ ﻋﻠﻰ (DAI) Dental Aesthetic Indexﻜﻤﺎ ﻫﻭ ﻤﻭﺼﻰ ﻤﻥ ﻗﺒل ﻤﻨﻅﻤﺔ ﺍﻟﺼﺤﺔ ﺍﻟﻌﺎﻟﻤﻴ ﹶﺔ ).(WHO ﺃﻅﻬﺭﺕ ﻨﺘﺎﺌﺞ ﺍﻟﺩﺭﺍﺴﺔ ﺒﺄﻥ ﺃﻜﺜﺭ ِﻤ ﻥ ﺍﻟﻌﻴﻨ ِﺔ ﻟﺩﻴﻬﻡ ﺘﺭﺍﻜﺒﺎﺕ ﺴﻨﻴﺔ ﺃﻤﺎﻤﻴـﺔ . ﻥ ِ % 40ﻤ ﻥ % 31ﻤﻥ ﺍﻷﻁﻔﺎل ﺍﻟﺫﻴﻥ ﺘﻡ ﻓﺤﺼﻬﻡ ﺴـﺭﻴﺭﹰﺍ ﻟـﺩﻴﻬﻡ ﻜﻤﺎ ﻜﺸﻔﺕ ﻨﺘﺎﺌﺞ ﺍﻟﺩﺭﺍﺴﺔ ﺒﺄﻥ ﺃﻜﺜﺭ ِﻤ ﻥ ﺍﻟﻌﻴﻨـ ِﺔ ﻥ % 24ﻤِـ ﺃﺴﻨﺎﻥ ﺃﻤﺎﻤﻴﺔ ﻤﺘﺯﺍﺤﻤﺔ ﺒﻴﻨﻤﺎ ﺘﺒﺎﻋﺩ ﺃﻷﺴﻨﺎﻥ ﺍﻷﻤﺎﻤﻴﺔ ﻭﺠﺩ ﻓﻲ ﺃﻜﺜﺭ ﻤِـ ﻥ ﺍﻟﻌﻴﻨ ِﺔ .ﻭﻜﺎﻨﺕ ﺍﻟﻔﺘﺤﺔ ﺍﻟﻌﻠﻭﻴﺔ ﺍﻟﻭﺴﻁﻴﺔ)≤2 ﻭﺍﻟﻔﺘﺤﺔ ﺍﻟﻌﻠﻭﻴﺔ ﺍﻟﻭﺴﻁﻴﺔ ﻅﻬﺭﺕ ﻓﻲ ِ %14.2ﻤ ﻤﻠﻡ( ﺃﻜﺜﺭ ﺘﺭﺩﺩﹰﺍ ﻟﺩﻯ ﺃﻹﻨﺎﺙ. ﻥ ﻥ 3ﻤﻠـ ِﻡ ﻭ %2ﻤِـ ﻋ ﹾﻨ ﺩ ﻩ ﺒﺭﻭﺯ ﻓﻲ ﺃﻷﺴﻨﺎﻥ ﺍﻷﻤﺎﻤﻴﺔ ﺃﻜﺒﺭ ِﻤ ﻥ ِ ﻤِﻥ ﺍﻟﻌﻴﻨ ِﺔ %32ﻜﹶﺎ ﻋ ﹾﻨﺩﻩ ﺒﺭﻭﺯ ﺤﺎ ﺩ )≤ 6ﻤﻠﻡ( . .ﺍﻟﺒﺭﻭﺯ ﺍﻟﻤﻌﻜﻭﺱ ﻟﻸﺴﻨﺎﻥ ﺍﻷﻤﺎﻤﻴﺔ ﺴﺠل ﻓـﻲ 10.7 ﻥ ِ ﺍﻟﻌﻴﻨ ِﺔ ﻜﹶﺎ %ﻤﻥ ﺍﻟﻌﻴﻨ ِﺔ ﻭﻜﹶﺎ ﻥ ﺍﻟﻤﺭﺤﻠـ ِﺔ ﺍﻟـﺴﻨﻴﺔ ﺨ ﹶﺘﻠﹶﻁﺔ ﻤِـ ﻥ ﺃﻜﺜ ﺭ ﺴﻴﺎﺩﺓ ﻓﻲ ﺍﻟﻤﺭﺤﻠ ِﺔ ﺍﻟﺴﻨﻴﺔ ﺍﻟﻤﺘﺄﺨﹼﺭﺓ ﺍﻟ ﻤ ﹾ ﻥ ﻥ ﺍﻟﻌﻴﻨ ِﺔ ﻭﺘﹶﺭﺍﻭﺤـﺕ ﻤِـ ﺍﻟﻤﺒﻜﹼﺭﺓ ﺍﻟﺩﺍﺌﻤﺔ .ﺍﻟﻌﻀﺔ ﺍﻷﻤﺎﻤﻴﺔ ﺍﻟﻤﻔﺘﻭﺤﺔ ﻭﺠﺩﺕ ﻓﻲ ِ % 8.3ﻤ ﻋ ﹾﻨ ﺩ ﻫﻡ ﺘﻁﺎﺒﻕ ﻀﺭﺴﻲ ﻏﻴﺭ ﻁﺒﻴﻌﻲ. ﻥ ِ ﻥ ﺍﻟﻌﻴﻨ ِﺔ ﻜﹶﺎ 1ﻤﻠﻴﻤﺘ ِﺭ ﺇﻟﻰ 5ﻤﻠﻴﻤﺘ ِﺭ % 31 .ﺘﻘﺭﻴﺒﹰﺎ ِﻤ ﻁ ﺒﺎﻟﺠﻨﺱ ﻭﺍﻟﻤﺭﺤﻠـﺔ ﺍﻟـﺴﻨﻴﺔ ﻭﺠِﺩ ﺴﻭﺀ ﺍﻹﻁﺒﺎﻕ ﻓﻲ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴ ِﺔ ﺒﺸﻜل ﻤﻠﺤﻭﻅ ﻤﺭﺘﹶﺒ ﹶ ﺱ ﺒﻤﻭﻗﻊ ﺍﻟﺴﻜﻥ ﺃَﻭ ﺍﻟﺤﺎﻟﺔ ﺍﻟﻭﻅﻴﻔﻴﺔ ﻟﻸﺒﺎ ِﺀ. ﺕ ﺍﻟﻤﺨﺘﻠﻔ ِﺔ ﻓﻲ ﺍﻟﻴﻤﻥ ، ،ﻟﻜﻥ ﻟﹶﻴ ﺒﺎﻟﻤﺤﺎﻓﻅﺎ ِ ﻥ ﺍﻟﻌﻴﻨـ ِﺔ ﻟـﺩﻴﻬﻡ ﺘﺒﻴﻥ ﻤﻥ ﻨﹶﺘﺎﺌِﺞ DAI ﺍﻟﺘﻲ ﺴﺠﻠﺕ ﻓﻲ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴﺔ ﺒﺄﻥ ِ % 63.4ﻤ ﺤﺎﺠﺔ ﻗﻠﻴﻠﺔ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ﻭ %17.7ﻟﺩﻴﻬﻡ ﺤﺎﺠﺔ ﺇﺨﺘﻴﺎﺭﻴﺔ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴـﺔ, ﻭ %13.0ﻟﺩﻴﻬﻡ ﺤﺎﺠﺔ ﺸﺩﻴﺩﺓ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ,ﻭ %6.0ﻟﺩﻴﻬﻡ ﺤﺎﺠـﺔ ﺇﻟﺯﺍﻤﻴـﺔ ﺇﻟـﻰ ﺍﻟﻤﻌﺎﻟﺠ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ. ﻥ ﺒﻌﻤـﺭ ل ﺍﻟﻴﻤﻨﻴـﻴ ِ ﺩﻟﺕ ﻨﹶﺘﺎﺌِﺞ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴ ِﺔ ﻋﻠﻰ ﺇﻨﺘﺸﺎﺭ ﻋﺎﻟﻲ ﻟﺴﻭﺀ ﺍﻹﻁﺒﺎﻕ ﻓﻲ ﺍﻷﻁﻔﺎ ِ ﺕ ﻤﻭﺜﻭﻗ ِﺔ ﺘﺸﻜل ﺍﻟﻠﺒﻨﺔ ﺍﻷﺴﺎﺴﻴﺔ ﺒﺨﺼﻭﺹ ﺇﻨﺘﺸﺎ ِﺭ ﻭﺘﻭﺯﻴـ ِﻊ ﻁ ﺒﻴﺎﻨﺎ ﹶ 12ﺴﻨ ﹰﺔ,ﻜﻤﺎ ﺇﻨﻬﺎ ﺘﺯﻭﺩ ﺒﺨ ﹼ ﺴﻭﺀ ﺍﻹﻁﺒﺎﻕ ل .ﻜﻤـﺎ ﺸـﻜل ﺇﺩﺭﺍﺝ ﺍﻟﻤﻜﻭﻨـﺎﺕ ﻭﺍﻟﺤﺎﺠﺔ ﻟﻠﻤﻌﺎﻟﺠ ِﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ﻟﻸﻁﻔـﺎ ِ ﻥ ﺒﻌﻤﺭ 12 ل ﺍﻟﻴﻤﻨﻴﻴ ِ ﻋﺩﺓ ﺨﺼﺎﺌﺹ ﺇﻁﺒﺎﻗﻴﺔ ﻓﻲ ﺍﻷﻁﻔﺎ ِ ل ﻓﺭﺼ ﹰﺔ ﻟﺘﹶﻘﻴﻴﻡ ِ ﻥ ﺍﻟﺩﻟﻴ ِ ﺍﻹﻁﺒﺎﻗﻴ ِﺔ ﻜﺠﺯﺀ ِﻤ ﺴﻨ ﹰﺔ. ل ﺘﻘﺭﻴﺒﹰﺎ ﺒﻌﻤـ ِﺭ ﻥ ﺤﻭﺍﻟﻲ 25.300ﻁﻔ َ ﺍﻋﺘﻤﺎﺩﺍ ﻋﻠﻰ ﻨﺘﺎﺌﺞ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴ ِﺔ ﻴﻤﻜﻥ ﺘﻘﺩﻴﺭ ﺒﺄ 12ﺴﻨﺔِ ،ﻟﺩﻴﻬﻡ ﺤﺎﺠﺔ ﺇﻟﺯﺍﻤﻴﺔ ﺴﻨﻭﻴﺔ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ. ﻥ ﺍﻟﻐﺭﺒﻴ ِﺔ ﻟﻜـﻥ ﻥ ﺘﻠﻙ ﻓﻲ ﺍﻟﺒﻠﺩﺍ ِ ﻜﻨﺘﻴﺠ ﹰﺔ ,ﺍﻟﺤﺎﺠﺔ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ ﻓﻲ ﺍﻟﻴﻤﻥ ﺃﻗل ِﻤ ﻥ ﻜـﻲ ﺽ ﺒﺸﻜل ﻭﺍﻀﺢ ،ﻤﻤﺎ ﻴﺸﺩﺩ ﻋﻠﻰ ﺩﻭ ِﺭ ﺘﻭﻋﻴﺔ ﺼﺤ ِﺔ ﺍﻷﺴـﻨﺎ ِ ﺏ ﻋﻠﻰ ﺍﻟﻤﻌﺎﻟﺠ ِﺔ ﻤﻨﺨﻔ ﺍﻟﻁﻠ ل ﺃﻥ ﻴﺨﻀﻌﻭﺍ ﺇﻟﻰ ﺍﻟﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﻘﻭﻴﻤﻴﺔ. ﺘﹶﺸﺠﻊ ﺍﻷﻁﻔﺎ ِ List of Figures Figure 4-1: The percentage distribution of the late mixed dentition stage 88 and early permanent dentition stage for the total sample… Figure 4-2: Distribution of missing maxillary and mandibular incisors, 90 canines and premolars by gender………………………………. Figure 4-3: Distribution of incisal crowding for the total sample.............. 93 Figure 4-4: The prevalence of incisor spacing for the total sample…… 96 Figure 4-5: Prevalence of maxillary midline diastema in 12-year-old 100 Yemeni school children……………………………………… Figure 4-6: Prevalence of diastema (>2mm) in 12-year-old Yemeni 101 school children…………………………………………………. Figure 4-7: Mean maxillary midline diastema width (in mm) by 104 governorate………………………………….. Figure 4-8: Distribution of maxillary overjet for the total sample………….. 108 Figure 4-9: Distribution of the total sample according to their overjet 109 values by gender…………………………………… Figure 4-10: Mean maxillary overjet (in mm) by governorate………………… 112 Figure 4-11: distribution of anterior mandibular overjet for the total 113 sample…………………………………………………………… Figure 4-12: Mean vertical anterior open bite by gender……………………….. 117 Figure 4-13: Distribution of total sample according to their DAI scores….. 124 Figure 4-14: Mean DAI scores by governorate. ……………………………………. 127 Figure 4-15: Distribution of DAI scores by gender and residency……………. 130 List of Tables Table 2-1: Epidemiological indices……………………………………… 15 Table 2-2: Indices of treatment need………………………………… 17 Table 2-3: Indices of treatment outcome…………………………… 19 Table 2-4: Indices of treatment complexity………………………… 20 Table2-5: Causes of small/large area variations in orthodontic services 26 Table 2-6: Methodological and statistical design concerns for 27 studies on service discrepancies……………………………………. Table 2-7: The components of the standard DAI regression equation 38 and their actual and rounded regression coefficients (weights) Table 2-8: The DAI groups of severity of malocclusion and treatment need 38 Table 2-9: Comparison of various international studies in which the DAI 39 was used…………………………………………………… Table 2-10: Reported prevalences of objective orthodontic treatment need 45 Table 2-11: Reported prevalences of Subjective orthodontic treatment need 46 Table 2-12: Reported prevalences of the awareness of malocclusion…….…. 48 Table 2-13: Reported effects of malocclusion on functions……………………… 50 Table 2-14: Reported rankings of the occlusal anomalies causing 50 concerns to the patients…………………………………….. Table 3-1: The size of the realized sample for the 12-year-old group……... 59 Table 3-2: Intra- and inter-examiner calibration of parametric data 72 using paired t-test…………… Table 3-3: Intra- and inter-examiner calibration of non-parametric 72 data using percentage of agreement………………… Table 4-1: Number and distribution of all the examined children……………. 74 Table 4-2: Number and distribution of valid case sheets………………………… 75 Table 4-3: Distribution of the examined children according to history 75 of orthodontic treatment by governorate……… Table 4-4: Distribution of the examined children according to history of orthodontic treatment by gender…………….. 76 Table 4-5: Distribution of the examined children according to history 76 of orthodontic treatment by residency…………. Table 4-6: Distribution of the answers to question 1 regarding the 78 alignment of the children teeth by governorate……… Table 4-7: Distribution of the answers to question 1 regarding the 78 alignment of the children teeth by gender…………….. Table 4-8: Distribution of the answers to question 1 regarding the 79 alignment of the children teeth by residency…………. Table 4-9: Distribution of the answers to question 2 regarding the type 80 of malalignment of teeth by governorate……….. Table 4-10: Distribution of the answers to question 2 regarding the type 80 of malalignment of teeth by gender………………. Table 4-11: Distribution of the answers to question 2 regarding the type 81 of malalignment of teeth by residency…………… Table 4-12: Distribution of the answers to question 3 regarding the effect 82 of malalignment of teeth by governorate…….. Table 4-13: Distribution of the answers to question 3 regarding the effect 82 of malalignment of teeth by gender……………. Table 4-14: Distribution of the answers to question 3 regarding the effect 83 of malalignment of teeth by residency………… Table 4-15: Distribution of the answers to question 4 regarding the reason 85 for not seeking treatment by governorate….. Table 4-16: Distribution of the answers to question 4 regarding the reason 86 for not seeking treatment by gender………….. Table 4-17: Distribution of the answers to question 4 regarding the reason 87 for not seeking treatment by residency…….. Table 4-18: The percentage distribution of dentition stage by gender……… 89 Table 4-19: Percentage and frequency distribution of missing maxillary 91 and mandibular incisors, canines and premolars by gender… Table 4-20: Percentage and frequency distribution of missing maxillary 92 and mandibular incisors, canines and premolars by residency Table 4-21: Prevalence of crowding in the incisal segments by gender…… 93 Table 4-22: Prevalence of crowding in the incisal segments by residency... 94 Table 4-23: Prevalence of crowding in the incisal segments by dentition stage……………………………………………. 95 Table 4-24: Percentage and frequency distribution of crowding 95 by governorate………………………. Table 4-25: Prevalence of spacing in the incisal segments by gender…………97 Table 4-26: Prevalence of spacing in the incisal segments by residency….. 98 Table 4-27: Prevalence of spacing in the incisal segments by dentition 98 stage……………………………………………….. Table 4-28: Percentage and frequency distribution of spacing by 99 governorate………………………………. Table 4-29: Percentage distribution of the severity of maxillary midline 100 diastema in the affected group………………… Table 4-30: The prevalence of midline diastema by gender...................... 101 Table 4-31: Gender distribution of diastema (>2mm) in 12-year-old 102 Yemeni school children............................................. Table 4-32: Percentage distribution of midline diastema and midline 102 diastema >2mm in the affected group........................ Table 4-33: Percentage and frequency distribution of diastema by 103 governorate.................................................................. Table 4-34: The prevalence of maxillary and mandibular anterior 105 irregularity................................................................... Table 4-35: Percentage and frequency distribution largest maxillary 106 anterior irregularity by residency................................ Table 4-36: Percentage and frequency distribution of largest maxillary 106 anterior irregularity by dentition stage....... Table 4-37: Percentage and frequency distribution largest mandibular 107 anterior irregularity by residency............. Table 4-38: The percentage distribution of maxillary overjet by gender....109 Table 4-39: The interaction between maxillary overjet and gender.......... 110 Table 4-40: Distribution of maxillary overjet by gender and dentition stage 110 Table 4-41: The percentage distribution of maxillary overjet 111 by governorate.............................. Table 4-42: Gender distribution of anterior mandibular overjet in 114 12-year-old Yemen school children............................. Table 4-43: Distribution of anterior mandibular overjet by residency 114 and gender........................................................ Table 4-44: The percentage distribution of mandibular overjet by 115 dentition stage............................................................. Table 4-45: Percentage and frequency distribution of vertical anterior 115 openbite for the total sample........................ Table 4-46: The percentage distribution of vertical anterior openbite of 116 the affected group................................................... Table 4-47: Gender distribution of vertical anterior open bite in 116 12-year-old Yemeni school children.................................. Table 4-48: The percentage distribution of vertical anterior openbite and 118 dentition stage...................................................... Table 4-49: The percentage distribution of vertical anterior openbite by 119 governorate............................................................. Table 4-50: The interaction between vertical anterior open bite according 119 to governorates by AVOVA test................... Table 4-51: Prevalence of the antero-posterior molar relationship........... 120 Table 4-52: The percentage distribution of antero-posterior molar relation 121 for males and females................................... Table 4-53: The percentage distribution of antero-posterior molar relation 121 by residency............................................... Table 4-54: The percentage distribution of antero-posterior molar relation 122 by dentition stage.......................................... Table 4-55: Distribution of total sample according to their DAI scores..... 123 Table 4-56: Orthodontic treatment need of 12-year-old Yemeni children 125 according to the DAI...................................... Table 4-57: The frequency and percentage distribution of the DAI groups 126 for the sample by governorate........................ Table 4-58: The frequency and percentage distribution of the DAI groups 128 by gender......................................................... Table 4-59: The frequency and percentage distribution of the DAI groups 129 by residency..................................................... Table 4-60: The percentage and frequency distribution of the DAI groups 131 by employment status of parents.................... Table 5-1: Reported prevalences of received orthodontic treatment…………135 Table 5-2: Reported prevalences of missing teeth………………………………… 142 Table 5-3: Reported prevalences of crowding………………………………………. 145 Table 5-4: Reported prevalences of spacing……………………………………..…. 148 Table 5-5: Reported prevalences of maxillary central diastema……………… 151 Table 5-6: Reported prevalences of maxillary and mandibular anterior 153 irregularities……………………………………….. Table 5-7: Reported mean overjet and prevalences of increased overjet… 156 Table 5-8: Reported prevalences of mandibular overjet.......................... 158 Table 5-9: Reported prevalences of antero-posterior molar relation………. 162 Table 5-10: Reported orthodontic treatment need using DAI……………….. 164 Chapter one Introduction & Review of literature 1.1 INTRODUCTION Physical appearance may be the single variable feature having the greatest impact on self-esteem, behavioural patterns and personal interactions. Ideally, everyone should have a fair opportunity to attain his or her full potential and no one should be disadvantaged from achieving this. Orthodontics is one of the disciplines sharing the opportunity of providing children with a confident smile and a functional occlusion, thereby improving their quality of life.1 Although almost all oral diseases and in particular malocclusions, may not be life-threatening, they are important noble health issues. Furthermore, malocclusion has a large impact on individuals and society in terms of discomfort, social and functional limitations.1 Malocclusions are clinically significant variations from the normal range of growth and morphology. In contrast to disease and pathological lesions, malocclusion may be the result of a combination of minor variations from the normal; each is too mild to be classed abnormal but their combination summates to produce a clinical problem.2 The oral health needs of the population could be defined, as that quantity of dental services which expert opinion believes ought to be consumed over a relevant period of time in order for its members to remain or become as “healthy” as is permitted by existing dental knowledge.3 This is also termed normative needs.4 The opinion of orthodontists as to treatment needs may differ considerably from that of the dentist and the general public.5 1 Chapter one Introduction & Review of literature Consumers perceived needs (wants) are based on their awareness of potential disease and on personal experience, and depend on culture, religious, educational and social status. As such, they are an important determinant of consumer behaviour, i.e. a determinant of what economists call demand.6 Demand derives from a desire and attempt by the public to seek oral health care.7 Striffler defined desire plus the ability to obtain dental services as effective demand.8 In contrast, potential demand refers to the desire for care without the ability to attain it. Demand therefore reflects the ability of individuals to translate perceived needs (wants) into professional contact, and this in turn is clearly determined by organisational factors such as economy, time, ease and convenience of access, and income.9 The extent to which these factors influence the potential demand will eventually determine the effective demand or utilisation of health services. The difference between demand and utilisation is often called unmet demand or illmet demand.6 Priorities should not be developed solely based on the demand for treatment. Health promotion can alter a community’s perception of the problems and hence priorities. Priorities should be established through a partnership between the community and the professional advocates for oral health. The community should be involved in setting goals that are stated in terms of oral health, oral disease, oral health promotion, equity, training, personnel and health service.1 Despite efforts in the Arab world in the past decades to make health systems more equitable, access to dental health care is still far from adequate especially in poor communities. 2 Chapter one Introduction & Review of literature 1.2 AIM The aim of this study was to evaluate the prevalence and severity of malocclusion and orthodontic treatment needs in a sample of 12-yearold Yemeni school children using the Dental Aesthetic Index (DAI), and to assess the relationship between malocclusion and certain sociodemographic variables. 1.3 GOALS • To establish reliable base-line data regarding the prevalence, distribution and severity of malocclusion of 12-year-old children in selected rural and urban areas in Yemen. • To provide useful epidemiological data on the orthodontic treatment needs of 12-year-old Yemeni children of the selected areas. • To determine if the malocclusion, as defined by the DAI is affected by socio-demographic variables such as gender and socio-economic backgrounds. 1.4 PROBLEM STATEMENT Isolated studies in the Arab world have been carried out in the past.10-14 However, no recent data on the prevalence, distribution and severity of malocclusion or the orthodontic treatment need of the population representative of the whole of Yemen is available. The lack of data on the distribution, prevalence and severity of malocclusion in Yemen could be affecting the effective planning for the orthodontic 3 Chapter one Introduction & Review of literature services, which is needed to address the ever-increasing demand for orthodontic treatment. The potential interest (priorities) in orthodontic treatment for an increasing proportion of children will undoubtedly affect the type of services provided, as well as organisation and delivery systems.15 1.5 RATIONALE Provincial oral health management require accurate data on the prevalence, distribution and severity of malocclusion and the orthodontic treatment need of its child population. Such data is essential for the effective planning of education, training and deployment of dental manpower and resources as well as the distribution thereof.16, 17 As public interest in oral health increases, the demand for orthodontic treatment will increase; it is important to have epidemiological data to estimate the total need for orthodontic care services.15 The epidemiological data on orthodontic treatment need is of interest for dental public health programs, clinical treatment, screening for treatment priority, resource planning, and third party funding.18 While the above mentioned conclusions may be true in some countries, in Yemen no study has ever investigated the perception of the occlusal status as well as the need and demand for orthodontic treatment. However the present investigation has been planed to achieve that goal. 4 Chapter 0ne Introduction & Review of literature LITERATURE REVIEW 2.1 MALOCCLUSION: The term ‘normal occlusion’ encompasses minor deviations from the ideal that do not constitute aesthetic or functional problems. It is not possible to specify precisely the limits of normal occlusion and so there can be disagreement even between experienced clinicians about the categorization of borderline cases (19). Lawrence F. Andrews (20) gave the six keys to normal occlusion which are: 1- Molar relationship: The mesio-buccal cusp of the maxillary first molar occludes with the mesial surface of the mesio-buccal groove of the mandibular first molar. For a normal occlusion in addition it is necessary for the maxillary first molar disto-buccal cusp to be in contact with the mesial surface of the mandibular second molar. 2- Crown angulation (tip): It is the crown angulation and not the angulation of the entire tooth. The gingival portion of the long-axis of each crown is distal to the incisal portion varying with each individual tooth. 3- Crown inclination (torque): This refers to the labio-lingual or bucco-lingual inclination of the long-axis of the crown not the inclination of the long-axis of the entire tooth. 4- Rotation: No rotations. 5- Spaces: No spaces, tight contact points. 6- Occlusal plane: The plane of occlusion varies from generally flat to a slight curve of Spee. 5 Chapter 0ne Introduction & Review of literature The above six keys contribute individually and collectively to the total scheme of occlusion and therefore are viewed as essential to successful orthodontic treatment. Appreciable deviations from the ideal that might be considered aesthetically or functionally unsatisfactory are called malocclusion (19) . The fact that an individual has a malocclusion in itself is not a justification for treatment. Only if it is possible to say with certainty that the patient will benefit, esthetically or functionally, and only if he is suitable and willing to undergo treatment, should orthodontic intervention be considered (21). 2. 1. 1 ETIOLOGY: Multiple theories had been suggested to explain the etiologic factors of malocclusion. Generally, all of them fall into two categories: hereditary and environment. In the old days, under the influence of Edward Hartley Angle, the role of environment was largely exaggerated refusing the genetic effect. Nevertheless, jaw relations and soft tissue patterns reflect similarity between family members and relatives, indicating the effect of genetics on occlusion (22). Potter and Nance, reported that the inheritance of tooth size and dental occlusion occur as a result of multigenic system in which the action of multigens together with environmental factors will present the final results of the dental character (23). On the other hand, Graber and Swain reported that malocclusion incidence increase in modern societies, relating this to environmental factors. Also, Begg & Kesling and Corruccini & Whitely, theorized that the increased attrition of teeth caused by primitive diet prevent crowding development with age (24-26). 6 Chapter 0ne Introduction & Review of literature Harris and Johnson studied the heritability of skeletal and toothbased variables in a longitudinal study at 4, 14 and 20 years of age. They demonstrated that several craniofacial parameters that are important in craniofacial growth showed significant heritability. In contrast, the occlusal and arch parameters were affected minimally by genetic influences and experienced increasing influence from environmental factors throughout postnatal growth (27). Cassidy et al. studied the genetic influence on the dental arch form and found that arch width and Angle’s classification showed appreciable genetic influence, while tooth rotations and overjet are primarily influenced by environmental factors (28). A number of primarily environmental causes are known such as habits, trauma, caries, periodontal disease, chronic nasal obstruction with mouth breathing, and reduced masticatory stresses resulting from the soft consistency of food in urbanized societies (29,30). 2.1.2 UNFAVORABLE SEQUELAE OF MALOCCLUSION: The following can be considered unfavorable sequelae of malocclusion (31):1- Unfavorable psychological and social sequelae. a. Introversion, self-consciousness. b. Responses to uncomplimentary nicknames like Bugs bunny. 2- Poor appearance. 3- Interference with normal growth and development and accomplishment of normal pattern as crossbite causing facial asymmetries. 4- Improper or abnormal muscle function. 7 Chapter 0ne Introduction & Review of literature a. Compensatory muscle activities such as hyperactive mentalis muscle activity, hypoactive upper lip, increased buccinator pressures and tongue thrust, that occur as a result of spatial relationship of teeth and jaws. These activities are unfavorable and serve to increase the departure from normal. b. Associated muscle habits. 5. Improper deglutition because of changed function as a result of adaptive demands. 6- Mouth breathing. 7- Improper mastication. 8- Speech defects. 9- Increased caries incidence. 10- Predilection to periodontal disease. 11-Temporomandibular joint problems: functional problems. 12- Predilection to accidents. 13-Impacted and unerupted teeth, possible follicularcysts, damage to other teeth. 14-Prosthetic rehabilitation complications: space problems, teeth tipped and receiving abnormal stress. 2.2 EPIDEMIOLOGY OF MALOCCLUSION Epidemiology could be defined as: “The study of diseases and other conditions in human populations where the group rather than the individual is the unit of intakes”. There are two important features in this definition: The inclusion of “health related conditions” indicates that epidemiology is not just a study of diseases, but of any condition, that affects a large segment of the population. It is the epidemiologist’s task to help ensure that people do not turn into patients (32). 8 Chapter 0ne Introduction & Review of literature The aim of epidemiologic studies of malocclusion is to describe and analyse the prevalence and distribution of malocclusion in various populations, the ultimate goal being to identify etiologic factors (33) . Abundant epidemiologic data relating to malocclusion have been compiled over this century, but the epidemiology of malocclusion has been lingering at the descriptive stage. The present knowledge of the epidemiology for occlusal anomalies includes the following: • General agreement exists that malocclusions have a multifactorial aetiology and that the two basic categories are genetic and environmental. • The effective organisation and planning of orthodontic services within the public health service require accurate data on the orthodontic treatment need of the child population (17). The complexity of malocclusion necessitates that epidemiologic studies be based on some kind of classification. The number of combinations of single traits of malocclusion is practically infinite; a comprehensive classification of malocclusion for epidemiologic purposes cannot be made into a limited number of types (34). Helm suggests that the logical approach is to base such classification on the single traits of malocclusion. A given malocclusion trait represents a certain variation of the morphological variables concerned (33). 2.3 CLASSIFICATION OF MALOCCLUSION: Classification is grouping of clinical cases of similar appearance for ease in handling. It is not a system of diagnosis or a method determining prognosis or a way of defining treatment. Indices have been used to categorize medical and dental disorders 9 for the purposes of Chapter 0ne Introduction & Review of literature epidemiology, research, and to allocate patients into categories of treatment need (35). Malocclusion has proved to be a difficult entity to define, because individual perceptions of what constitutes a malocclusion problem differ widely. As a result, no generally accepted epidemiological index of malocclusion has been devised (8). A good method of recording or measuring malocclusion is important for documentation of the prevalence and severity of malocclusion in population groups. This kind of data is not only important for the epidemiologist, but also for those who plan for the provision of orthodontic treatment in a community or for the training of orthodontic specialists, If the method is universally accepted and applied, data collected from different population groups can be compared. A method that measures malocclusion quantitatively can also be used to assess treatment effects of orthodontic appliances (36). 2.3. 1 IDEAL INDEX OF OCCLUSION: The requirements for an ideal index of occlusion are similar to the requirements of any dental index, and these are: 1- Status of the group is expressed by a single number, which corresponds to a relative position on a graduated scale with definite upper and lower limits; running by progressive gradation from zero, i.e. absence of disease, to the ultimate point, i.e., disease in its terminal stage. 2- The index should be equally sensitive throughout the scale. 3- The index should correspond closely with the clinical importance of the disease stage it represents. 4- Index value should be amendable to statistical analysis. 10 Chapter 0ne Introduction & Review of literature 5- Reproducible. 6- Requisite equipment and instruments should be practicable in actual field situation. 7- Examination procedure should require a minimum of judgment. 8- The index should be facile enough to permit the study of a large population without undue cost in time or energy. 9- The index would permit the prompt detection of a shift in group conditions, for better or for worst. 10-The index should be valid during time. These requirements Organization Report (37) were summarized in a World Health as points 1 to 9. Summers added point 10 to the list and explained what he meant by ‘validity during time’. According to Summers, developmental changes in occlusal disorders may consist of either a ‘basic orthodontic defect’ or a ‘symptom’ of a developmental change. A basic orthodontic defect may be defined as a constant occlusal dysfunction, whereas a symptom of a developmental defect may be defined as an adaptation to development that may be an accommodation either to normal growth or to a basic orthodontic defect. A symptom may either be constant (present at all ages) or variable (fluctuating with age). An index must concentrate on, and be sensitive to the basic orthodontic defect, and must not be unduly sensitive to the symptom (38,39). By definition, then, for an index to be valid during time, the index score for the occlusal disorder should either remain constant or increase during time, indicating that the occlusal disorder is the same or getting worse. The index score should not decrease during time, indicating that the occlusal disorder is getting better. This is because, although there is frequent mention in the literature of the self11 Chapter 0ne Introduction & Review of literature correction of malocclusion, there are actually few instances of selfcorrected malocclusions (40). (41) Bergström and Hailing also added four desirable qualities of an ideal index, these are: 1. High validity, i.e. the index measures what it was designed for. 2. Wide assessment base. 3. High reliability, i.e. the evaluation should be reproducible. 4. Easy to learn and use. 2.3.2 HISTORY OF MALOCCLUSION INDICES: Many orthodontists have developed classification methods, and among them are Kingsley Dewey Proffit (50) , Hellman (56) (42) , Angle (51,52) and Elsasser (43-45) , Case (53,54) , Simon , Anderson (46-48) , Bennett (49) , (55) , Ackerman and (57) . However, by far the most universally accepted classification in use today is Angle’s method, which was developed a century ago. Angle’s classification was readily accepted by the dental profession, since it brought order out of what previously had been confusion regarding dental relationships. However, it was recognized almost immediately that there were deficiencies in the Angle system. One of the most severe critics was Calvin Case. In 1912, in a report to the British Society for the Study of Orthodontics, Norman Bennett suggested that malocclusions be classified with regard to deviations in the transverse dimension, the sagittal dimension, and the vertical dimension (49) . This recommendation, rejected at the time, was later realized in the work of Simon and the development of his system of gnathostatics (53). Simon related the teeth 12 Chapter 0ne Introduction & Review of literature to the rest of the face and cranium in all three dimensions of space. His approach, although somewhat complex, clearly represented an advance. If it had not been for the introduction of roentgenographic cephalometrics in the 1930’s and 1940’s, gnathostatics probably would have made a greater impact on present-day orthodontics. Simon, Lundström, Hellman, and Horowitz and Hixon recognized the need to differentiate dentoalveolar and skeletal discrepancies and to evaluate their relative contributions towards the creation of a malocclusion. These authors suggested that classification should include this type of diagnosis and point logically to a treatment plan (5861) . After that a number of indices of malocclusion were proposed and used, most of which record specific conditions. The Malalignment Index assesses rotation and tooth displacement, whereas the Occlusal Feature Index records crowding and cuspal interdigitation and vertical and horizontal overbite (62,63) . The HLD Index was used for assessing treatment need in New York State (64). Grainger developed the Treatment Priority Index (TPI) for the same purpose, and this index has been used in national studies of orthodontic needs of children (65). The Federation Dentaire lnternationale (FDI) attempted to develop its own internationally accepted and simplified method of determining malocclusion. The result, however, was a carefully qualified description of a method of measuring occlusal traits (66). The WHO based its assessment on a ‘present/absent’ basis. The WHO suggests that a dentofacial anomaly be recorded as present if in the judgment of the examiner one or more of four criteria are met (67). 13 Chapter 0ne Introduction & Review of literature 2.4 EPIDEMIOLOGICAL ORTHODONTIC SURVEY METHODS As researchers push the boundaries of the known into the realm of the unknown, the area of epidemiology with respect to orthodontics has become an increasingly important area of study. It behooves the present day orthodontic clinical researcher to assess the criteria that have become the foundations of treatment planning in orthodontics and extract the crucial elements and incorporate them into a manageable epidemiological index derived from the already existing treatment planning indices (68). In the orthodontic context, an index is used to describe a rating or categorizing system that assigns a numeric score or alphanumeric label to a person's occlusion. There are five types of indices, each for a distinct purpose. Indeed, it is the purpose rather than content or conventions of an index that distinguishes it. 2.4.1 DIAGNOSTIC CLASSIFICATION Angle's classification is the best known of this type, its subclasses often being used to describe incisor and buccal segment relationships separately. These classifications serve their purpose reasonably well, allowing ease of communication between orthodontists (43). 14 Chapter 0ne Introduction & Review of literature 2.4.2 EPIDEMIOLOGICAL INDICES These indices record every trait in a malocclusion to allow estimation of the prevalence of malocclusion in a given population; for example, the epidemiologic registration of malocclusion described by Summer's Occlusal Index (OI), the Federation Dentaire Internationale (FDI) method or Björk et al. (38, 66) Other indices of this type score tooth alignment in a way that allows study of tooth irregularity and periodontal diseases, or treatment stability (69-71). A summary of the more important indices is presented in (Table 2-1). 15 Chapter 0ne Introduction & Review of literature Table 2-1: Epidemiological indices TYPE Malalignment Index (MI) (62) Occlusal Feature Index (OFI) (63) "FDI" Commission on Classification and Statistics for (66) Oral Conditions (COCSTOC) An Objective Method of Epidemiological Registration of (69) Malocclusion Dento- Facial Index (DFI) (72, 73) Index of Tooth Position (ITP) (74) Quantitative Assessment of the (75) Occlusal Features METHOD Each arch was divided into three segments; two posterior and one anterior. A score of; '0' = ideal alignment '1' = minor malignment '2' = major malignment Population studies. Most important features of occlusion; lower anterior crowding, cuspal interdigitation, vertical overbite, horizontal overjet. Reliable in a validation study with reasonable inter-examiner reliability and good correlation with treatment need Disadvantages Unreliable (did not take into account the relationship between the upper and lower teeth in occlusion) Records three categories of occlusal features; dental anomalies intra-arch and interarch relations. FDI system is used to describe individual tooth malrelations. 567 symptoms which allowed the data to be analysed by a computer. Based on in three main criteria; a) anomalies in the dentition b) anomalies in the occlusion c) deviations in space conditions Designed for clinical examination of patients with a full complement of permanent teeth (excluding third molars) Subjective (scores were allocated on a scale of 0-9; where 'O' = 'normal' occlusion) Unwieldy and too complex for clinical use Dentofacial Morphometric Measurements Anthropological studies Quantitative measurements based on individual teeth as units of occlusion and recorded as"maloccluded" or "aligned" Each arch was divided into three segments; two posterior, and one anterior. Measures five main occlusal features for epidemiological studies; overjet, overbite, posterior crossbite, buccal segment crowding, incisor segment alignment Unreliable (no indication of relative severity) 16 Four instruments were required to aid in the intra-oral measurement of the occlusal features Chapter 0ne Introduction & Review of literature 2.4.3 TREATMENT NEED (TREATMENT PRIORITY) INDICES Several indices have been developed to allow categorisation of malocclusion according to the level of treatment need. Examples of these are Summer's Occlusal Index (OI), Draker's Handicapping Labio-lingual Deviations (HLD) Index, Grainger’s Treatment Priority Index (TPI), and Salzman's Handicapping Malocclusion Assessment, the Dental Aesthetic Index (DAI). These indices have been primarily designed for epidemiological purposes, but have also been used to determine treatment priority. These indices yield a score for each trait or component that is then weighted to calculate an overall score (38, 64, 76-78). Another method of assigning treatment priority is to establish a list of conditions or traits in categories that denote the extent to which treatment is considered necessary. An example of these is the Swedish National Board for Welfare Index, which determines whether or not a patient's malocclusion falls within the scope of treatment in the Swedish public dental services. Similar indices in Norway, the NOTI are used to determine the level of public health co-payment that the patient may be entitled to, i.e. there may be total reimbursement for severe malocclusion such as associated with cleft lip and palate and partial or nil reimbursement for malocclusions considered minor. The Index of Orthodontic Treatment Need (IOTN) is used primarily in Great Britain (7981) . A summary of the more important indices is presented in (Table 2-2). 17 Chapter 0ne Introduction & Review of literature Table 2-2: Indices of treatment need TYPE 'Summers' Occlusal Index (38) (SOI) METHOD One of the most reliable and valid indices of treatment need. Two divisions and seven syndromes described using the Occlusal index. Handicapping LabioLingual Deviation Index (64) (HLDI) No special equipment necessary Presence or absence of specified criteria was noted and score& cleft palate, trauma-related malocclusions, overjet, labioluigual spread (severe displacement of teeth) 375 twelve year old children from three Ontario communities. Defined seven "syndromes" of malocclusion. Five grades of treatment need were determined based on 10 criteria of malocclusion Endorsed by the AAO and the ADA. No need for a millimeter gauge, therefore fewer clerical errors. Treatment Priority Index (76) (TPO) Handicapping Malocclusion Assessrnent Record (77) (HMAR) Swedish Index for Need of Orthodontic Treatment (79,83) Index of Orthodontic (81) Treatment Need (IOTN) Matched-Pair Similarity (82) Technique Norwegian Index (84) Initially designed to designate dental health and aesthetic. Impairment Eventually a morphological and a functional index were added Rank malocclusion based on occlusal traits for dental health and aesthetic impairment. Incorporated a Dental Health Component (DHC) and an Aesthetic Component (AC). Population was divided into two groups. 40 attributes were measured with a score of 'near perfect' to 'extreme malocclusion' Four categories of treatment need from 'very great need' to 'little or no need' 18 DISADVANTAGES Criticized for being timeconsuming and a cumbersome scoring system. Fails to score missing teeth other than upper incisor. Penalizes cases with a full unit pre-or post-normal molar relation although they do not cause static or functional occlusal interferences Does not account for missing, impacted or spacing between teeth. Ignores transverse discrepancies such as midline deviations and cross-bites. Component weightings are subjective. Does not account for spacing, midline deviations, arch asymmetry, missing teeth due to trauma or caries. Lack of mixed dentition analysis. Cannot be applied to cases with missing first molars. Subjective component weightings. Cannot be used in the mixed dentition. No intermediate severity levels, Poorest levels of reliability and validity Vague and arbitrary grade divisions lead to low levels of reproducibility Criticized due to lack of ability to assess dento-facial imbalance in the antero-posterior plane Inadequate theoretical basis Based on morphological and functional indices Chapter 0ne Introduction & Review of literature Type Standardized Continuum of (85) Aesthetic Need (SCAN) California Modified Index (86) (CalMod) Method Based on perception of dental aesthetics in the U.K. using ten photographs with a scale from 1 (attractive) to 10 (unattractive). Simple to use with a high level of reliability even when used by non-dental personnel If any of the five conditions is present, the score column is marked with an 'x" and there is no need to score further ; cleft palate, deep impinging overbite, crossbite of individual anterior teeth, severe traumatic deviations, overjet greater than 9mm with incompetent lips or reverse overjet greater than 3.5mm with reported masticatory and speech difficulties Disadvantages Criticized for using only a twodimensional guide (photos) with an insufficient catalogue of dental aesthetics (only ten photos), and the photographic view itself may affect the perception of dental attractiveness Has been tested in the courts in California twice. A "lawsuit" driven index, 2.4.4 TREATMENT OUTCOME INDICES Assessment of the outcome of treatment or the changes resulting from treatment is a further potential use of occlusal indices. Several indices have been developed to evaluate treatment success (87-89) . Summer's Occlusal Index (OI) has also been used to assess the outcome of treatment (38) . The Peer Assessment Rating (PAR) Index has been developed specifically for this purpose (90) . A summary of the more important indices is presented in (Table 2-3). 19 Chapter 0ne Introduction & Review of literature Table 2-3: Indices of treatment outcome TYPE Grading Orthodontic (87) Treatment Peer Assessment Rating (90) (PAR Index) Efficiency of Orthodontic (91) Treatment Critical Evaluation of (92) Orthodontic Treatment METHOD Based on ten accepted criteria for orthodontic correction, 'Percentage achievement' was obtained for each factor which required correction Based on five criteria; upper and lower anterior contact point displacement, right and left buccal occlusion in three planes of space, overjet, overbite, dental centerline relation. Percentage. PAR score change is reliable providing a quantitative and reproducible measure of treatment success, High reliability when used by non-dental personnel Based on fifteen morphological criteria Points were assigned with more severe conditions rating a higher score Skeletal and dental outcome criteria included; sagittal, vertical, transverse occlusion, alignmnent, axial inclination, apical resorption. First attempt to incorporate iatrogenic tooth damage into an index of treatment outcome 20 DISADVANTACES Method of grading was biased towards improvement with five points allotted for full correction of a feature but only one point deducted for worsening of the condition Criticized for failing to assess axial inclination of anterior teeth post-treatment, for only measuring static tooth position, ignoring dynamic occlusion, facial aesthetics, iatrogenic decalcification, root resorption, and periodontal breakdown Subjective nature of the allocation of points Inadequate theoretical basis Chapter 0ne Introduction & Review of literature 2.4.5 TREATMENT COMPLEXITY INDEX The recently developed Index of Complexity, Outcome and Need (ICON) measures treatment complexity, the outcome of the orthodontic treatment and orthodontic treatment need (93). A summary of this index is presented in (Table 2-4). Table 2-4: Indices of treatment complexity TYPE METHOD Index of Complexity Outcome Based on expert opinion of 97 (93) practicing specialist and Need (ICON) orthodontists from 9 countries. For use clinically or on study models, For use in clinical governance, audit, research and decision making. Five weighted components taking approximately 1 minute to answer, aesthetic component (IOTN), upper arch crowding/spacing and impacted teeth, crossbite, incisor openbite, incisor overbite, buccal segment DISADVANTAGES Inadequate theoretical basis. Has not been validated. 2.5 WHY USE INDICES? Increasing demands for quality assurance (i.e. service accountability, cost-effectiveness, etc.) from an increasingly informed, educated (either via secondary school education or by television advertisements), and image-conscious, litigious public may pose a serious conflict to the future delivery of dental services by the dental profession. Marked discrepancies in the provision of orthodontic services either between different specialists or specialists and generalists are, however, no longer consistent with the growing demands for the 21 Chapter 0ne Introduction & Review of literature transparent accountability from the public. This includes the provision of orthodontic services, illustrated by an opinion that "the inexorable unfavorable patient response from excessive use by inadequately trained orthodontists and unqualified pediatric dentists and general practitioners, has produced a wave of frustration and backlash to functional (orthodontic) appliances in many quarters" (94). Although the lack of adequate training by general practitioners in diagnosis and treatment planning is particularly relevant to the provision of functional appliances, this problem also embraces other orthodontic services such as space maintainers (95, 96). For instance, whereas the early provision of orthodontic services is conventionally assumed to improve the resolution of Class II malocclusions, more recent evidence suggests that little advantage is to be gained by early intervention (97) . Variable post-retention outcomes are also serious threats to the provision of quality orthodontic services, although these may be resolved by reducing the marked variations in retention protocols (98-101) . Meticulous strategic planning will therefore be mandatory to maintain future market growth for orthodontic services, especially in view of the marked variation in these threats across different – locales (102). The provision of orthodontic services was considered previously as the exclusive domain of those with advanced training, for example, orthodontic specialists. However, it is not the progressive provision of such services by non-specialists that is perceived as a "market threat"; but the lack of quality assurances (103) . The potential impact of these threats may be illustrated when a provider (specialist or generalist) fails to identify a true Class III malocclusion, e.g. where the mandible is rotated down and back to a moderate Class II relationship. If the provider then applies a Class II functional appliance to such a 22 Chapter 0ne Introduction & Review of literature camouflaged Class II malocclusion, the outcome will exacerbate rather than resolve the skeletal anomaly. Similar concerns apply to the use of conventional functional appliances and cervical pull headgear in cases characterized by excessive lower anterior face height, since they may potentially induce further increases in lower face height, increased downward and backward mandibular rotation and anterior openbite (104). Clearly such orthodontic failures will only be resolved by strategic development of diagnostic protocols to improve the quality assurances of patient assessments (diagnosis) prior to treatment planning. In order to appreciate the importance of these market threats, regional discrepancies in the provision of orthodontic services will first be reviewed, followed by a discussion of the principle threats to the specialist orthodontic market. These are then followed by consideration of the need to priorize orthodontic service complexity and the utility of clinical evidence-based guidelines to constrain the provision of inappropriate services. 2.6 WHY DISCREPANCIES IN THE PROVISION OF HEALTHCARE (INCLUDING ORTHODONTIC) SERVICES POSE SIGNIFICANT MARKET THREATS? The most serious threats to the orthodontic market are the result of the wide discrepancies in the provision of services, since matching epidemiological data in support of the differential prevalences in malocclusions are Limited (102, 104-108) . Such concerns are not unique to orthodontics, but are generic to other dental markets (109-113) to surgical deliveries, tonsillectomies and hysterectomies (e.g. admission rates) and physician visits , in addition (114-116) , hospital (111,117,118) . Numerous hypotheses have been advanced to account for these discrepancies in 23 Chapter 0ne Introduction & Review of literature the provision of health care services. These generally center around either patient (e.g. disease prevalence, socioeconomic characteristics, etc.) or provider characteristics (e.g. specialists or generalists providing the service). Unfortunately, relatively few studies have been undertaken to evaluate the clinical aspects of these discrepancies or their differential service outcomes (119, 120). Moreover, the principal concerns tend to center on the provision of excessive services by some providers, rather than the under servicing by others, although the latter may be equally reprehensible (121). Strategic development to accommodate these concerns is however, complicated by the tendency for service excesses to be provided by outlier groups, although these anomalies usually become evident only when they are retrospectively assessed by "expert" panels (119, 120). These concerns are particularly relevant to the provision of orthodontic services, although a recent British study considered there was no justification for singling out outliers for special audits due to the lack of objective methods to assay criteria of an "ideal occlusion" are applied to define orthodontic service need, approximately 97% of the service quality (122). Nevertheless, if strict population would be defined in need (123). The provision of such service volumes would be difficult to rationalize, however, since resources will never be sufficient to provide unlimited demands, regardless of their mode of financing. These concern are further underscored by discrepancies between traditional methods to assess the needs for orthodontic services. For instance based on the 5point of the Sweden National Board of Health and Welfare, 64 % for one child population sample were identified to be "in need of" orthodontic services, whereas when the Treatment Priority Index was applied to a 24 Chapter 0ne Introduction & Review of literature similarly aged but different sample, 38% were "in need of' such services. As such discrepancies cannot be rationalized by epidemiological data, the need to devise scientifically supported clinical guidelines to define the most cost-effective services for specific occlusal discrepancies cannot be overstated. For instance, even when orthodontic service expenditures are entirely covered by state-benefits, a recent review of 1584 adolescents (15-16 years of age) showed that the provision of orthodontic services is not solely determined by the degree of malocclusion, but also the dental attendance record of the mother, in addition to other factors (124-126). Marked discrepancies in the provision of healthcare (including orthodontic) services may alternatively reflect professional uncertainties regarding the most appropriate services to provide for particular conditions (114). Proponents of this "uncertainty hypothesis" maintain that reasonable specialist and non-specialist providers may be anticipated to arrive at different conclusions regarding the provision of orthodontic services in the absence of accurate comparative data on their effectiveness. This hypothesis also implies that, whereas specialist and non-specialist providers may agree on the indications for orthodontic services that are clearly appropriate and on those that are clearly inappropriate, there are significant controversies for the large middle gray area. But whereas this uncertainty hypothesis may explain wide discrepancies in the provision of orthodontic services that fall within this gray area, there is no consensus whether the greatest source of uncertainty (e.g. premolar extraction) relates to the precision of the diagnosis or the outcome of a particular service (127-129). Existing evidence is, however, most consistent with a differential "enthusiasm" hypothesis. This contends that discrepancies in the 25 Chapter 0ne Introduction & Review of literature provision of services primarily reflect variations in the prevalence of providers who are "enthusiasts" about particular services or service groups. Although the supportive data primarily relate to the provision of surgical services, there is a general consensus that such enthusiasm may originate from local training (e.g. continuing education courses), in which a particular authority communicates his/her enthusiasm to the audience, Convened "enthusiasts" may then convince his⁄ her referral base concerning the potential advantages of such services, which may then be reflected by large discrepancies in their local provision. Moreover, services are even more susceptible to such "enthusiasm" when specialists are not required, since then primary providers (generalists) both evaluate the service need and subsequently provide the service (130132) . Whereas these hypotheses furnish potentially useful explanations for discrepancies in the provision of orthodontic services by different providers, their eventual impact will depend on the variable and differential weighted primary determinants. (Table 2-5) In view of complex interactions between such market determinants generally two basic format are evident. The first is generally designed to determine if significant discrepancies actually exist, with the primary objective to ascertain whether they are greater than expected by chance (133) . The second type of study is designed to evaluate the basic causes of provider discrepancies, mainly centering on the relationships between dependent and independent determinants of service need. The advantages of this latter type of study are illustrated by data from New England, which indicated that the provision of surgical services is a function of the number and type of specialists in the area. Although analogous data apply to the provision of orthodontic services, little data 26 Chapter 0ne Introduction & Review of literature is available concerning the differential provision of orthodontic services by non-specialists (134, 135) . Moreover, the interpretation of data from these studies tend to be compromised by significant methodological and statistical deficiencies, that are difficult to resolve (Table 2-6). Table 2-5: Causes of small/large area variations in orthodontic services. Cause Potential Impact Malocclusion Differential orthodontic service rates may be correlated with prevalence variations in malocclusion prevalence in the local area Access to specialist Variation in specialist service access for an area may be a services function of their orthodontic service demands Clinical judgment Unique practice styles of different communities may correlate with the supplies of specific services Lack of appropriate care by one class of providers may Quality of care result in increased demands for others to rectify the service outcome Local communities may have inherent characteristics that Patient behavior influence (how and when) their demands for specific orthodontic services Random Fees Small populations with apparently analogous occlusal discrepancies may experience random demands for specific services. Fees vary in different areas of the country and between rural versus urban areas The type of advertising whether it is by the local orthodontic Advertising association or the internal advertising which is done by the individual practice. Adapted from Chassin (136) and Parchman (137) 27 Chapter 0ne Introduction & Review of literature Table 2-6: Methodological and statistical design concerns for studies on service discrepancies Potential deficiency Center of controversy Is data for the provision of orthodontic Definition of small area services related to a coherent catchment area? Is the population used to construct the orthodontic service rate may representative Population at risk of the population at primary risk? (i.e. do the samples comprise the diverse socioeconomic proportions characteristic of the community?) Are there enough small areas included in the Sample mix analysis to detect significant differences in orthodontic service provisions? Statistical versus clinical Is the variation in the provision of orthodontic services clinically significant? significance Is the adjustment for the underlying Case mix adjustment malocclusion prevalence and orthodontic service demand appropriate? Are the observed variations in the provision of orthodontic services stable over time? Stability of rates Adapted from Chassin (136) The most logical strategic response to these factors which impact on the provision of orthodontic services involves the development of evidence-based clinical practice guidelines to define the most appropriate orthodontic service for specific malocclusions. Progress in this regard has, however, been lamentably slow in comparison with many medical conditions (138) . Yet if they are not devised by the profession, they will clearly be developed and imposed on service delivery by some (e.g. 28 Chapter 0ne Introduction & Review of literature government or insurance) third-party. In order to underscore the need for such guidelines, the most serious threats to the provision of quality orthodontic services are reviewed. 2.7 THE PRINCIPAL THREATS TO THE SPECIALIST ORTHODONTIC MARKET Potential threats from the continued specialist manpower education are relatively insignificant compared to those following the progressive adoption of market-driven healthcare reforms (managed care and preferred provider options, etc.) by private (e.g. insurance) and public (e.g. government) institutions. For instance, third-party payments have become increasingly important economically for patients, providers and the insurance industry, due to spiraling dental service costs, i.e. eligibility for private dental insurance benefits in the U.S. have increased from 4.5 million dollars in 1967 to 100 million dollars in 1985 (139). As most private third Party basic dental insurance benefits have been broadened to include contributions for specialty (e.g. orthodontic) services, the potential impact of the recently introduced American healthcare reforms on the orthodontic market cannot be overstated. These threats are particularly relevant to specialists, since the constraint of specialist referral systems is such an integral component of these reforms (140-142). Moreover, these concerns are particularly relevant to the provision of orthodontic services, due to the lack of an objective system to distinguish between the services provided by specialists as opposed to non-specialists (94). Recent reductions in the general population of dental caries prevalence is a subtle, but significant, threat to the demand for dental (including orthodontic) services, This reflects the growing realization that socioeconomic improvements are primarily responsible 29 Chapter 0ne Introduction & Review of literature for these changes, rather than the provision of dental services. As a result, third-party indemnity programs are unlikely to allocate additional resources for the provision of dental (e.g. orthodontic) services, without more evidence for their inherent benefits. But if the provision of orthodontic services increasingly becomes the domain of generalists, due to their lower service fees, then the potential market threat will be their inadequate quality assurances (143). Discrepancies in the perceived need for orthodontic services between different (specialist or generalist) providers are, however, potentially more serious factors, due to their inferred inconsistent initial patient assessments (i.e. diagnoses) (108,114) . These concerns were recently underscored by comparisons of the orthodontic service needs based on the assessments of 240 casts by 97 orthodontists from 9 European countries (102) . These data indicated that the country of origin and method of payment were primary determinants of the providers' prescribing behaviors, rather than the specific orthodontic needs of patients (144) . This inevitably leads to the suspicion that significant discrepancies between the European and North American requirement for specialist orthodontic services primarily reflect the differential availability of specialist service access and priorities assigned to the public's discretionary funds rather than differences in the prevalence of malocclusions (145,146). Such epidemiological comparisons are, however, further compromised by national and regional discrepancies in healthcare (including orthodontic) service fees. For instance, since all healthcare providers tend to maximize their incomes by adjusting their work pattern, then marked discrepancies in the provision of orthodontic services may reflect the higher case-loads required to compensate the 30 Chapter 0ne Introduction & Review of literature low service fees in fee-for-service payment systems. Similarly, the increased provision of orthodontic services by non-specialist providers may be a function of their reduced case load for other conventional dental services: a trend that may be exacerbated in the future (147). A general lack of understanding on how clinicians diagnose and plan orthodontic services for their patients is a further problem. For instance, following upon the suggestion that a problem-based approach would facilitate the evaluation of medical records; a similar system has been devised for the provision of orthodontic services based on five major characteristics of a malocclusion (56, 148). Essentially, this comprised synthesis of the Angle (43) classification with a Venn diagram to improve analysis of the interrelationships between dependence on study models for initial case assessments are therefore alarming, since they may be responsible for some of the unacceptable discrepancies in the orthodontic services provided to homologous groups of patients. These discrepancies are illustrated by data derived from the examination of pretreatment records of 148 subjects by 5 orthodontic specialists, where disagreements in their classifications were reported for 29% of the adult subjects and 27% of the adolescents. Moreover, these orthodontists failed to agree either to extract or not to extract teeth as part of the orthodontic services for more than one third of the patients, in addition, one or more of the specialists believed that surgery was probably or definitely the most appropriate service for 29% of the adults and 23 % of the adolescents, although the initial criteria for sample selection specifically excluded the need for orthognathic surgery (149-151). These concerns were further underscored by a more recent study, where 39 orthodontic specialists evaluated pretreatment records (study models, radiographs, photographs etc.) for 6 patients. In addition to 31 Chapter 0ne Introduction & Review of literature surprising variations in their classifications of maxillary and mandibular molar relationships, significant discrepancies were reported for their assessments of crowding or spacing and overbite. These data therefore underscored the fact that some of the orthodontists included in this study not only failed to provide precise assessments, but their discrepancies would have resulted in either incorrect or inappropriate service (i.e. the 39 orthodontists included in this study recommended 39 different forms of services for the 6 patient sample). Clearly, inconsistent initial assessments of potential orthodontic patients comprise fundamental market threats (152). 2.8 THE NEED TO PRIORIZE ORTHODONTIC SERVICE COMPLEXITY A more objective system is therefore necessary not only to standardize the initial patient assessment, but also to priorize their orthodontic service needs with particular emphasis on the distinction between those which could be provided more effectively by specialists as opposed to generalists. Since orthodontics cannot be transformed from an "art" to a "science" without such a system, the significance of this dilemma cannot be overstated. Data derived from 52 Florida schoolchildren illustrate the deficiencies of the present system, since they indicated that assessments for some variables (e.g. posterior cross bites, acceptable mandibular anterior crowding, facial convexity, overbite, overjet and molar classification) were more reliable than others (e.g. maxillary/mandibular antero-posterior position, incisor exposure, interlabial gap and maxillary overcrowding) (153) . Such deficiencies should be sought to be improved in 32 Chapter 0ne Introduction & Review of literature this era of transparent accountability, since varying assessments of specific diagnostic parameters compromise the diagnostic process. Marked regional disparities in the provision of orthodontic services, without supportive epidemiological data on their differential service needs, further exacerbate these concerns. They not only point to unacceptable inconsistencies in the initial orthodontic assessment (i.e. diagnosis), but also in the subsequent treatment planning and predicted service outcomes (154,155). A number of indices have been developed over time in an effort to improve initial assessments, amongst others, the Index of Orthodontic Treatment Need (IOTN) and the Peer Assessment Record to describe the malocclusion (90,156) . There are many potential advantages for these indices, including the: • identification of the orthodontic service need • prediction of potential service difficulty (e.g. complexity), i.e. the discrimination between cases requiring specialist from non-specialist services. Unfortunately, the significance of these index scores remains controversial, without a gold standard to define the orthodontic service need (157). In addition, assessments of orthodontic service needs depend on many parameters other than the initial diagnostic evaluations (e.g. service objectives, limited or extensive, national service complexities, appliance designs, patient cooperation, growth pattern, payment systems, providers' abilities, etc.). Since these inter-related parameters are difficult to incorporate into a single index, the American Orthodontic Association has yet to recognize their intrinsic value (158). There are, however a number of inherent reservations for the development of such an index. These include difficulties in defining 33 Chapter 0ne Introduction & Review of literature service complexity, especially since mild and/or severe malocclusions may require services that are either simple and/or very complex. Moreover, the Index of Orthodontic Treatment Need (I0TN) score is an inadequate assay for service complexity, since this index essentially grades the anticipated disadvantages of leaving malocclusions without orthodontic services. The Peer Assessment Rating (PAR) index is similarly imperfect, since the score essentially provides an index of change resulting from the orthodontic services. Both forms of index are, however, relatively easy to use and their scores are functions of malocclusion severity. Unfortunately they offer no indication of the complexity of the services required to resolve a malocclusion (159, 160). Although an Index of Orthodontic Treatment Complexity (IOTC) would conceptually offer many potential benefits, including the discrimination between services provided by specialists and nonspecialists, there are also a number of potential disadvantages. For instance, such assessments may change with advances in orthodontic service technology (160). In addition, there are many patient (e.g. service objective, growth potential, compliance, general and oral health) and provider (e.g. specialist and non-specialist) determinants of treatment complexity, in addition to the malocclusion itself, which are difficult to incorporate into a single index (159) . There are also concerns for the distinction between ideal and optimal services, where optimal is defined as the most appropriate that can be realistically delivered for a specific individual patient (158) . There are therefore concerns whether the IOTC should be primarily directed to the provision of ideal or optimal services for a patient. This is a particular concern for epidemiological studies designed to compare the orthodontic service needs for specific 34 Chapter 0ne Introduction & Review of literature populations, since the derived data are difficult to interpret if the primary ideal or optimal goals cannot be distinguished (159). This then begs the question how research should progress, when the real concern is to identify specific cases whose diagnosis and treatment planning should be performed by skilled and experienced orthodontic specialists. This important and fundamental concern not only relates to the provision of orthodontic services, but is equally relevant to the provision of many other healthcare services. Cases that may require services for longer periods than others must be distinguished from those that are truly complex. For instance a service may take longer than anticipated due to poor patient compliance, but this should not be taken as an index of genuine complexity (161). The crux of the problem, therefore, centers on the distinction between complexity and severity. Although severity can up to a point, be measured by the PAR index from study casts alone, this index does not necessarily help identify the complexity of a case, For instance, well aligned cases with either palatal canines or poor quality first molars will be scored low by the PAR Index but are amongst the most difficult cases for the provision of orthodontic services. Paradoxically, if the canine case were more crowded then the PAR Index would be increased, although less expertise would be required, due to potential resolution of the malocclusion by permanent and deciduous canine extraction. If logistical, medical, resource and social determinants are included; the role of the PAR lndex to delineate complexity will be further diminished (161). Clearly clinical guidelines are imperative to distinguish between cases that are truly complex (i.e. should be treated by a skilled and experienced specialist) and those that could be serviced by either specialist or non-specialist providers (161). 35 Chapter 0ne Introduction & Review of literature 2.9 THE DENTAL AESTHETIC INDEX (DAI) Although a number of classifications and indices have been suggested for characterisation of dento-facial anomalies, only a few have been adopted for general use outside the country of origin. This is partly due to considerable variation in socio-culturally-determined perceptions and the reactions to dentofacial appearance (15,162-164) . Although numerous indices have been developed, none as yet has been accepted universally. In the meantime, one of the indices available must necessarily be chosen. The selection of an index for measuring any condition is dependent upon two main factors (16,90). • The objective of the investigation i.e. the nature of the information required. • The ability of the examiner to consistently reproduce the diagnosis on which the index is based. The DAI score was selected for this study, due to the growing acceptance of this index in the orthodontic literature, initially derived from a regression equation linking objective measurements of ten occlusal traits to their relative social dental aesthetic acceptability (165). 2.9.1 ESTABLISHING MALOCCLUSION SEVERITY LEVELS ON THE DENTAL AESTHETIC INDEX (DAI) SCALE During the 1970s, the importance of psychosocial factors in the assessment of malocclusion was acknowledged in the USA and internationally. It was said that the definition of malocclusion was not one to be made by orthodontic clinicians alone. There was believed to be a salient need for the development of an orthodontic index containing psychosocial as well as clinical criteria (166-169). 36 Chapter 0ne Introduction & Review of literature The relationship between dental aesthetics and psychological and social well being has been noted by many investigators. Helm for instance, noted that ‘Concern for dental appearance is an essential factor in determining psychosocial need for orthodontic treatment’ (33) . Brook and Shaw stated that the assessment of a patients treatment need must include aesthetic impairment and by inference psychosocial need for orthodontic treatment (81). Stricker et al concluded that the psychosocial consequences of malocclusion due to unacceptable aesthetics may be as serious or even more serious than the biological problems (170). In response to the demand for an orthodontic index that includes psychosocial criteria in assessing need for orthodontic care and for use in epidemiological surveys; Cons et al developed the Dental Aesthetic Index (DAI) that integrated the psychosocial and physical elements of malocclusion (78). The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic norms. Which is a regression equation that links mathematically the public’s perceptions of dental aesthetics with the objective physical measurements of the occlusal traits associated with malocclusion. The DAI is particularly sensitive to occlusal conditions that have the potential for causing psychological or social dysfunction (78). The DAI includes the hypotheses that socially derived norms for acceptable dental appearance set the standard for evaluation of acceptable levels of dental aesthetics and that the conditions of malocclusion are socially defined by the deviation of occlusal configurations from social norms. Extreme deviations from acceptable 37 Chapter 0ne Introduction & Review of literature dental appearance should have a negative impact on social, psychological and physical function (78). The components of the DAI regression equation and their actual and rounded regression coefficients (weights) are shown in (Table 27). The Standard DAI regression equation calls for the measured components of the DAI to be multiplied by their rounded regression coefficients (weights); the summation of their products and the addition of a constant number to the total. The resulting sum is the DAI score. The regression equation for obtaining a DAI score is: DAI score = 6(missing incisors, canines and premolars) + (crowding) + (spacing) + 3(diastema) + (largest maxillary irregularity) + (largest mandibular irregularity) + 2(anterior maxillary overjet) + 4(anterior mandibular overjet) + 4(anterior openbite) + 3(antero-posterior molar relationship) + 13 (171). The standard DAI loses relatively little precision when regression weights are rounded. After an individuals score has been calculated it can be placed on a scale to determine the point at which the score falls between most and least aesthetic dental appearances. The further a DAI score falls from the norm of most acceptable dental appearance the more likely the occlusal condition, if left untreated, may be either socially or physically handicapping or both (78). The DAI, an orthodontic index that provides a single score linking the publics perceptions for dental aesthetics with objective measurements associated with malocclusion, has decision points along the DAI scale defining specified case severity levels. DAI scores of 25 and below represent normal or minor malocclusion with no treatment 38 Chapter 0ne Introduction & Review of literature needed or slight treatment need. DAI scores of 26 to 30 represent definite malocclusion with a treatment option considered elective. DAI scores of 31 to 35 represent severe malocclusion with treatment indicated as highly desirable. DAI scores of 36 and higher represent very severe or handicapping malocclusion with treatment considered mandatory (171) (Table 2-8). Table 2-7: The components of the standard DAI regression equation and their actual and rounded regression coefficients (weights) (171) . Regression coefficient Actual Rounded weights weights DAI components 1. Number of visible missing teeth (incisors, canines and premolars in the maxillary and mandibular arches) 2. Crowding in the incisal segment 3. Spacing in the incisal segment 4. Midline diastema 5. Largest maxillary irregularity 6. Largest mandibular irregularity 7. Anterior maxillary overjet 8. Anterior mandibular overjet 9. Vertical anterior openbite 10. Antero-posterior molar relation 11. Constant 39 5.76 6 1.15 1 1.31 1 3.13 3 1.34 1 0.75 1 1.62 2 3.68 4 3.69 4 2.69 3 13.36 13 Chapter 0ne Introduction & Review of literature Table 2-8: The DAI groups of severity of malocclusion and treatment (171) need DAI scores 13-25 Case sensitive level and relative treatment need Normal or minor malocclusion; No treatment need or slight need 26-30 Definite malocclusion; Treatment elective 31-35 Severe malocclusion; Treatment highly desirable 36 and higher Very severe (handicapping) malocclusion In their latest edition, Oral Health Surveys, Basic Methods, the World Health Organization incorporated the Dental Aesthetic Index (DAI) criteria for assessing dento-facial anomalies (32). In view of the recent endorsement of the DAI by the World Health Organization, this index was chosen as the instrument to conduct the present investigation. 2.9.2 EPIDEMIOLOGY OF MALOCCLUSION IN OTHER COUNTRIES - DEFINED BY THE DENTAL AESTHETIC INDEX Since it’s introduction in 1986 the DAI (78) had been used in many studies to describe the prevalence of malocclusion in different countries. A comparison of various international studies in which the DAI was used is summarised in (Table 2-9). A further discussion of each of these studies follows the table. 40 Chapter 0ne Introduction & Review of literature Table 2-9: Comparison of various international studies in which the DAI was used Author Country Age n 13-25 26-30 31-35 -36 Estioko et al. (172) Australia 12-16 268 63.4 18.7 11.9 6 Otuyemi et al. (173) Nigeria 12-18 703 77.4 13.4 5.5 3.7 Johnson and Harkness (174) Australia 10 309 20.1 24.5 22.4 33 Chi et al. (175) New Zeeland 13 150 20 33 20 27 Malaysia 12-13 1519 62.6 19.6 10.6 7.2 Malaysia 12-13 5112 51.2 24.7 14.2 9.9 Esa et al. (176) Abdullah and Rock (177) 41 Chapter 0ne Introduction & Review of literature Estioko et al. using the Dental Aesthetic Index (DAI) measured the distribution, prevalence and severity of malocclusion and orthodontic treatment need in a selected population of adolescents, to determine if the malocclusion so defined was affected by socio-demographic variables such as age, gender, ethnic and socio-economic background. Two hundred and sixty-eight secondary school children, aged 12- to 16-years from Heidelberg, Australia participated in the study. For each subject a questionnaire eliciting standard demographic information such as age, gender, parent's occupation, and ethnic origin was completed. The findings demonstrated that most subjects 63.4% had a dental appearance requiring no treatment. Only 6% of the subjects had malocclusions that needed mandatory treatment. Malocclusion, as defined in the study, was found to be significantly associated with age (172) . Otuyemi et al., investigated the distribution, prevalence and severity of malocclusion and treatment need amongst randomly selected (n = 703) rural and urban Nigerian children, aged 12-18 years (mean 14.0 ± 1.84) using the Dental Aesthetic Index (DAI). They also assessed whether malocclusion was affected by age, gender and socio-economic background. Most of the children 77.4% had a dental appearance that required no orthodontic treatment. Over 13 per cent fell into the group where treatment for malocclusion is considered to be 'elective'. A substantial proportion 9.2% of the population had severe to handicapping malocclusion where treatment was 'highly desirable' or 'mandatory'. There were no statistically significant differences in DAI scores between age groups, gender and socioeconomic background (173). Johnson and Harkness studied the need for orthodontic treatment in a random sample of 10-year-old, New Zealand school children in 42 Chapter 0ne Introduction & Review of literature Dunedin using the Dental Aesthetic Index (DAI). When absent or unerupted teeth were disregarded, orthodontic treatment was considered to be ‘mandatory’ for one third of the children. The remaining children were almost equally divided among the three other treatmentneed groups: ‘highly desirable’, ‘elective’, and ‘not necessary’. The majority of the children had crowding and spacing in at least one incisor segment, and a molar occlusion other than Angle Class I. In this predominately mixed-dentition sample, more children were considered to need orthodontic treatment than older children in studies using the DAI (174) . Chi et al. used the Dental Aesthetic Index (DAI) to assess the prevalence of unmet orthodontic treatment need in 150, 13-year-old school children in Dunedin, New Zealand. They also compared the findings with those obtained in the same children at 10 years of age. Fewer 13-year-olds 27% had a ‘mandatory’ need of orthodontic treatment, than when they were 10 years old 33%, 20% had ‘no/little’ need for orthodontic treatment, 33% had an ‘elective’ need for treatment and 20% had a ‘desirable’ need for treatment. The decrease in DAI scores is attributed to over-sensitivity of the index to mixed dentition traits. When the individual scores were analysed, only 7% of the 10-year-olds were given the same scores as when they were 13 years old, 52% were given higher scores and 41% were given lower scores. This disagreement between scores was masked to a limited extent by the DAI categories: 49% of the 10- year-olds were assigned to the same DAI category at 13 years of age, 20% to a greater treatmentneed category and approximately 30% to a lower treatment-need category. The DAI, in common with other malocclusion indices, is 43 Chapter 0ne Introduction & Review of literature unreliable over time because it is affected by developmental changes in the occlusal traits measured (175). Esa et al. evaluated malocclusion and orthodontic treatment need in a sample of 12-13-year-old Malaysian school children using the Dental Aesthetic Index (DAI). They also assessed the relationship between malocclusion and socio-demographic variables, perceptions of need for orthodontic treatment, aesthetic perception and social functioning. The sampling procedure involved a multistage, clustered and stratified random sampling technique. The sample comprised of 1519 school children attending 20 secondary government and government-aided schools in urban and rural areas of the Klang District in Peninsular Malaysia. There were 772 males and 747 females in the sample. For each subject a questionnaire eliciting standard demographic information such as gender, parents' income and ethnic origin and questions on perception of need for orthodontic treatment and satisfaction with dental appearance and function was completed. They found that most subjects 62.6% require no orthodontic treatment. Only about 7% had handicapping malocclusion that needed mandatory treatment (176). Abdullah and Rock assessed the prevalence and severity of malocclusion in a large sample of 12-13-year-old Malaysian children. A random sample of 5112 Malaysian children was drawn according to a multi-stage technique, which accounted for the ethnic composition of the population. Subjects were examined using both components of the Index of Orthodontic Treatment Need (IOTN) and the Dental Aesthetic Index (DAI). They found that the proportion of children in need of orthodontic treatment was 47.9% according to grades 4 and 5 of the dental health component (DHC) of IOTN and 22.8% according to grades 8-10 of the aesthetic component (AC). Using 31 points as the cut-off point for 44 Chapter 0ne Introduction & Review of literature treatment acceptance, the DAI index indicated that 24.1% needed treatment. Malocclusion, as defined in this study, was found to be significantly associated with gender and subjects' area of residence. There were no significant differences in mean DAI scores for Malays, Chinese and Indian children. Significant associations were found between DAI scores and perception of need for orthodontic treatment, satisfaction with dental appearance and social functioning (177). Ansai et al. used the Dental Aesthetic Index (DAI) to evaluate malocclusion in 15- to 18-year-old Japanese high school students (n = 409). This study used a sample of students from randomly selected urban and rural high schools in Japan's Kyushu district. The DAI scores for urban and rural high school students, as well as the total DAI scores from these two areas were significantly higher than that of American high school students. These results showed that the number of students with an acceptable dental appearance among Japanese high school students is significantly lower than among American high school students. This indicates a higher need for orthodontic treatment among Japanese high school students (178). 2.10 ORTHODONTIC TREATMENT NEED AND DEMAND: As growing public interest in oral health increases the demand for orthodontic treatment increases, it is important and valuable to have epidemiologic data to estimate the total need and demand for orthodontic care services (179) . The potential interest in orthodontic treatment for an increasing proportion of children will undoubtedly affect the type of services provided, as well as organization and delivery systems in the future (15). The orthodontic need and demand assessment is of interest for dental public health programs, clinical treatment, 45 Chapter 0ne Introduction & Review of literature screening for treatment priority, resource planning, and third-party funding (18). The assessment of orthodontic needs is difficult, controversial and varies, partly due to the lack of uniformity in diagnosis and partly due to a variety of social factors in each community. Thus in some countries missing or irregular teeth are a social embarrassment and stigma, whereas in another community they are hardly noticed (180). The results of many of the earlier epidemiological investigations are not comparable owing to subjective evaluation of the features registered and because only the most general conclusions were drawn from the mass of data obtained in the investigation of large population groups (69) . For this reason, and because of the desire to statistically analyse and compare epidemiological data, there has been a search for an occlusal index to record traits of malocclusion in numerical and categorical format and to enlist a degree of objectivity into their assessment (181). International studies report a remarkable variation in orthodontic need. Baseline data published by the World Health Organisation for 13- and-14 year-olds in 10 industrialised countries (not including the United Kingdom), revealed an orthodontic treatment need ranging between 21% and 64% (182). In the United Kingdom orthodontic treatment need increased from 5% in 1942, to 15% in 1954 and 70% in 1973 (183). Surveys on the prevalence of received orthodontic treatment have been concentrated in the Scandinavian countries giving percentages ranging from 16% to 57%, whereas Ast et al. (184) found that 9.6% of his American sample had undergone extractions or appliance treatment. On the other hand, Ng’ang’a et al. (185) found that 4% of Kenyan 13-15 year olds were orthodonticaly treated as presented in (Table 2-10). 46 Chapter 0ne Introduction & Review of literature Table 2-10: Reported prevalences of objective orthodontic treatment need. Treatment need (%) Sample Author None Little 31.2 28.3 Index Country Size Age Van Kirk & Pennell (62) America 620 2100 13 12-15 Linder-Aronson et al. (79) Brook & Shaw (81) Jenny &Cons (171) Otuyemi et al. (173) Sweden 2114 7-16 England 333 11-12 35.1 32.1 America 7500 12-17 45.8 25.2 Nigeria 703 12-18 77.4 13.4 Johnson & Harkness (174) New Zealand 10 23 22 22 33 DAI Ansai et al. (178) Ast et al. (184) Ingervall et al. (186) Myrberg &Thilander (187) Japan 409 15-18 32 21 25 22 DAI America 1413 15-18 4.7 14 HLDI Sweden 324 10 25 35 Sweden 5459 7-13 26 30 6-11 22.9 33.1 39.7 35.0 11-12 40.1 Kelly et al. American White American Blacks (188) Foster & Day (189) England 1000 Mild Moderate Great 25.2 26.8 9 39.8 Kelly & Harvey (191) American White American Blacks 12-17 10.5 14.7 Farah (192) Iraq 101 9-10 39 American White Native Americans 1337 485 15-18 12-17 46 19 26 26 Sweden 156 20-29 69.9 Norway 50 18 America 1306 Salonen et al. (194) Espeland et al. (195) Jenny et al. (196) Tuominen et al. (197) (198) Espeland et al. Ng’ang’a et al. (199) Mal Index 27.6 5.1 IOTN 15 14 DAI 9.2 30 10.2 44 23.7 15.0 35.2 13.7 16.9 TPI 34.6 36.9 25 25.7 21.0 29.2 27.4 TPI 15 25 13 30 DAI 10.3 11.5 8.3 ISMHB 65 28.3 6.7 15-18 45.7 23.6 15.5 15.2 DAI 41.8 10.9 29.1 23.6 16.4 20 IOTN TPI 61 Finland 340 16-19 12.7 45.5 Norway 73 35 52.1 39.7 8.2 Kenya 919 13-15 70.1 18.9 10.7 47 DAI 22.0% (extraction) 37.9% (appliances) Finland Jenny et al. 21.3 23.4 19-35 Hannuksela (190) (193) 22.3 21.5 NOTA NOTI 0.3 NOTI Chapter 0ne Introduction & Review of literature Several studies have investigated the prevalence and severity of malocclusion for specific ethnic groups, age distribution, and countryspecific populations; however fewer reports (187,188; 200-202) specifically addressed the need and demand issues for the orthodontic treatment of children. The results of orthodontic epidemiological studies on subjective treatment need are summarized in (Table 2-11). In planning orthodontic care, one should not only consider the prevalence of a disorder, but as importantly, the need for such care as expressed by specialists and the demand for treatment shown by the patients and their parents (200). Table 2-11: Reported prevalences of Subjective orthodontic treatment need. Author Batayine (14) Country Jordan Tuominen et al. (197) Finland Ingervall et al. (202) Sweden Tuominen et al. (203) Finland Abdulla (204) Iraq Size Age Subjective Treatment need 200 13 28.5% 200 15 25% 200 17 23% 340 16-19 24% 21-54 24% 226 21 19.5% 200 13 27% 200 15 25% 200 17 30% 48 Chapter 0ne Introduction & Review of literature Prahl-Anderson found that 14% of parents who were aware of their child’s malocclusion and did not want orthodontic treatment (205). In a study by Ingervall and Hedegârd, 60% of 18-year-old Swedish men were evaluated to have orthodontic need; however, only 4% were aware of the malocclusion and desired treatment (186) . Similarly, Myrberg and Thilander reported that, in a group of 7- to 13-year-old children who had very urgent or urgent need, as many as 52.2% declined orthodontic treatment (187). Gravely compared two regional areas where the number of practicing orthodontists and treatment levels were variable. He found that where treatment levels were high, the unacceptability of appliance therapy was reduced, thereby increasing demand for treatment (206). Whilst some regional and national differences are to be expected, such large variations in the reported need for orthodontic treatment are difficult to explain. The differences more likely reflect the inherent objectivity of the assessment system used and their questionable validity and reliability (207,208). This lack of accurate base line data has excluded orthodontics from the recommendations of the Federation Dentaire Internationale for a stepwise progression towards “Health for all by the year 2000” (209) . As a result; there have been urgent calls to remedy this problem by developing an internationally acceptable Index of Orthodontic Treatment Need (210). 49 Chapter 0ne Introduction & Review of literature 2.11 PERCEPTION OF OCCLUSION: Studying the prevalence of malocclusion and assessment of treatment needs in a community are important steps in planning orthodontic services. It is also equally important to study the demand for this service. This demand depends on the awareness of the problem and the perception of malocclusion, because not all patients with malocclusion seek orthodontic treatment (24). The results of some studies are summarized in (Table 2-12). Table 2-12: Reported prevalences of the awareness of malocclusion. Sample author Country Salonen et al. (194) Sweden Ng’ang’a et al. (199) Ingervall et al. (202) Kenya Sweden Size 156 179 793 Age 20-29 30-39 13-15 21-54 Awareness of Malocclusion (%) Males Females 25 36 29 38 34% 34% Many studies in this field concluded that the desire to improve appearance is the most important motive for seeking treatment (211-215) , while other studies concentrated on the effect of malocclusion on functions like speech and mastication. The results of these studies are listed in (Table 2-13). Studies on perception of malocclusion discussed the effects of various factors on the awareness of occlusal anomalies and the demand for treatment; among these factors are: 50 Chapter 0ne Introduction & Review of literature 1- Types of occlusal anomalies that lead to awareness and demand for treatment: Various studies have been conducted to assess which types of occlusal anomalies cause more concern to the patient and the results are listed in (Table 2-14) the occlusal anomalies are given numbers according to their importance to the subjects studied. 2- Gender: Some studies concluded that the awareness of malocclusion and demand for treatment is more for females than males (164, 189, 212). Also, women were found to be more dissatisfied with their dental appearance (216,217) . Other studies did not show significant differences between males and females in esthetic preference and concern over appearance (214,218). 3- Age: In some studies the effect of age as a factor on judgment of facial attractiveness was found to be not significant (164) . Also, it was not significant in the reliability and accuracy of identification of malocclusion (219) , while other studies showed that dissatisfaction with dental appearance increases with age (202,217). 4- Socio-cultural factors: Studies have shown that people generally under estimate their malocclusion, creating a gap between need and demand. However, most of these studies stress on the effect of social factors on treatment demand (202, 215, 219; 220). High social classes place greater value on facial appearance and this increases their demand for treatment (24,164) ; while in a study by Shaw (216) dissatisfaction with dental appearance was not associated with social class. 51 Chapter 0ne Introduction & Review of literature Table 2-13: Reported effects of malocclusion on functions. Author Batayine (14) Graber & Swain (24) Abdulla (204) Shaw et al. (216) Bond & Lawson (221) CentoFante et al. (222) Helm et al. (223) Results O.J. >9mm and/or openbite affect chewing ability Crossbite affects speech Severe malocclusion affects speech and mastication O.J. >9mm and/or openbite affect chewing ability Severe malocclusion causes little functional disability Malocclusion affects speech Malocclusion affects speech O.J. >9mm and/or openbite affect biting ability Table 2-14: Reported rankings of the occlusal anomalies causing concerns to the patients. Increased Author Batayine (189) Gosney 4 2 1 3 2 1 3 4 2 1 2 1 2 3 3 1 2 2 1 2 1 (202) (214) (215) Lindsay & Hodgkins Graber & Lucker Al-Huwaizi 3 (225) Deep Open bite bite 3 4 1 (204) Helm et at. Rotation 1 Ingervall et al. Abdulla Spacing OJ (14) Foster & Day Crowding (219) (224) 52 4 3 Chapter 0ne Introduction & Review of literature 2.11.1 METHODS OF STUDYING PERCEPTION OF OCCLUSION: These methods can be divided into two main types: 1- Questionnaires: This method is used to assess the individual’s perception of his or her occlusion by comparing the answers with an objective assessment of the individual’s occlusal status (14,204,214,217,226). In some studies on children’s perception of occlusion, the questionnaires are answered by the child and the parents (215,219). 2- Photographs: In studies employing this method the participants were either asked to identify their photograph from a series of photographs of teeth, or in some studies the participants are asked to rate a series of photographs of teeth according to their attractiveness (216, 220, 227). In some studies this method is modified by using slides instead of photographs (228). Studying perception of occlusion and awareness of malocclusion is important in planning health services on a community as well as on individual’s level, because the patient’s self image is a part of the behavioral history and affects the patient’s cooperation (229). 2.12 ORTHODONTIC SURVEYS: Epidemiological studies dealing with the prevalence of occlusal disharmonies and the actual need for orthodontic treatment are very necessary to use as background for proper orthodontic diagnosis and treatment planning (24). Foster (208) pointed out that the objectives of carrying out an orthodontic survey include one or more of the following: 1- Assessing occlusal features, 2- Assessing the level of treatment need and difficulty, 53 Chapter 0ne Introduction & Review of literature 3- Assessing the effects of a specified factor on the occlusion and vice versa, and 4- Screening for orthodontic treatment. The results of many of the earlier epidemiological investigations are not comparable owing to subjective evaluation of the features registered. Moreover, most conclusions have been drawn from the mass of data obtained in the investigation of large population groups (69). Occlusion is determined by a number of features each having continuous range of variations between extremes (189) . Subjective assessment of occlusal features is the main problem in epidemiological studies. To overcome this problem a clear definition must be set for the criteria to be used, and this will make the assessment more objective and reliable (38). Comparing studies on prevalence of malocclusion in different age groups of the same community, and between different communities, may throw light on the possible etiologic factors of malocclusion and provide better chances of preventing or reducing them. 2.12.1 CLASSIFICATION OF ORTHODONTIC SURVEYS: Epidemiological studies of malocclusion are difficult to group because of the wide scope of variables included under malocclusion, the differences in definitions, examination techniques and sampling methods. From the type of sample studied, orthodontic epidemiological studies can be classified into: 1-Normal occlusion studies which usually utilize a selected sample of who appear to have normal occlusion (e.g. class I occlusion) picked out from the population, schools, hospitals or dental (not orthodontic) clinics. 54 Chapter 0ne Introduction & Review of literature 2- Studies concerned with a specific type of malocclusion, obtaining the sample from retrospective or prospective orthodontic patient records, or screening the population for that specific malocclusion (230-233). 3- Prevalence studies of the different malocclusion features focusing on the distribution of each feature or combination of features, utilizing indices to categorize the severity of malocclusion, or the need for orthodontic treatment in: a) Population samples randomly selected from schools, phone books etc. b) Pretreatment orthodontic patients. c) Special population groups (as mentally handicapped). According to the examination techniques each study examined one or more of the following: 1- Occlusal features: a variety of occlusal features was included in the method of many studies including overjet (reversed, edge to edge, normal, increased, extreme or excessive), overbite (complete or incomplete, deep, traumatic), crossbite (bilateral, unilateral, false, true, scissors bite), crowding and spacing conditions, rotations and displacements of individual teeth, the teeth absent and present, and other dental anomalies. 2- Anteroposterior arch relationship either by Angle’s classification, canine classification, incisor classification or a combination of them. 3- Arch dimensions measured intraorally or on study model or wax prints, including maxillary and mandibular arch circumference, incisorcanine, canine-molar, intercanine, inter-premolar, inter-molar and vertical canine, premolar and molar distances, and depth of the palate. 55 Chapter 0ne Introduction & Review of literature 4- Space analysis studies including measurement of the mesiodistal width of teeth, arch circumference and space available whether clinically or radiographically (periapical or OPG) and some concluded prediction charts. 5- Indices of treatment need as the Handicapping Labiolingual Deviations, Treatment Priority Index, Dental Aesthetic Index, Index of Orthodontic Treatment Need, or the Peer Assessment Rating Index (64, 76,78,85; 234) . 6- Soft tissue analysis of the lip, tongue, nose or nasopharyngeal space in anterior view and profile by direct measurement, pictures, or radiographs. 7- Cephalometric studies including a variety of analyses of hard and soft tissue. 8- Facial deformities as cleft lip and palate and facial asymmetries. All the preceding makes it difficult to categorize the previously conducted epidemiological studies into clear and definite groups. 2.15 FINDINGS OF SOME PREVIOUS ORTHODONTIC EPIDEMIOLOGICAL STUDIES IN THE ARABIC WORLD The first extensive epidemiological study on occlusion was carried out in 1978 by Al-Alousi et al. The sample consisted of 952 senior secondary school Iraqi students involving three cities (Basrah, Baghdad and Mosul) and their environs (235). The Angle system for classifying the antero-posterior dental relationship was used. Other features recorded on a specially designed form were; overbite, overjet, crowding or spacing of 3mm or more in each of the posterior segments of both arches, the presence of crossbite or openbites. Based on the presence and severity of the above features each case was examined and classified subjectively as having either a 56 Chapter 0ne Introduction & Review of literature normal occlusion or a malocclusion. The results of this study showed that 86.8% Class I type occlusion (neutroccusion) was recorded, while Class II type was recorded in less than 8% of the sample in both sexes (235). Gardiner undertook a study to determine the dental status of a sample of 479, 12-year-old children living in Libya. Malocclusion was scored as present or absent, only gross anomalies were scored and cases were subdivided into Class I, II and III. Malocclusion was present in 97% of children, of which 77% had Class I; 18.2% had Class II and 4.8% had Class III malocclusions (10). In 1990, El-Mangory and Mostafa published the results obtained from a survey done in Egypt. A total of 501 subjects aged 18-24 years were examined and a Dewey-Anderson modification of Angle’s classification was used. It was found that 34.3% of the examined subjects had normal occlusion while, 65.7% had malocclusion of which 67.6% with Class I malocclusion, 16.2% with Class II division 1, 4.8% Class II division 2 and 10.6% with Class III malocclusion (11). Al-Emran examined 500 Saudi Arabian males aged 14 years. He suggested that 40% of the subjects were in need of comprehensive orthodontic treatment according to the criteria of the Norwegian Health Services (13). Saleh carried out a study aimed to provide oral health planners in Lebanon with information on the prevalence of malocclusion in schoolchildren in an attempt to define the target population for orthodontic services in future. A total of 851 schoolchildren (446 males and 405 females) aged 9-15 years were examined for malocclusion using Angle’s classification. In all, 59.5% of the sample had malocclusions, 35.5% of which were of dental origin and 24% had skeletal discrepancy; 19% Class II and 5% Class III malocclusions 57 (236) . Chapter 0ne Introduction & Review of literature Kerosuo et al. conducted a study to explore orthodontic treatment experience, subjective need for treatment, and perception of teeth and dental appearance in relation to background factors such as funding system, area of living, age, gender, ethnicity, and socioeconomic status. The subjects were 1076 randomly selected second-year high school students from a rural and an urban area of Kuwait, with a mean age of 15.1 year. Kuwaiti citizens constituted 79% of the sample, and the rest were of other nationality. The data was collected using a questionnaire. Orthodontic treatment rate was significantly higher for Kuwaitis 10% than for non-Kuwaitis 2%. Among Kuwaiti subjects, urban area of living and females gender increased the odds of receiving orthodontic treatment. Subjective treatment need was 36%, with no difference between Kuwaiti and non-Kuwaiti subjects, but Kuwaitis from the rural area expressed subjective treatment need less often than those from the urban area. The results suggested that access to free-of-charge orthodontic treatment was likely to affect treatment rate, whereas it did not seem to influence the self-perceived need for treatment (237). 58 Chapter two Material & methods MATERIAL AND METHODS 3. 3.1 SAMPLE 3.1.1 SAMPLING A two-staged cluster sample was used to draw the sample. In stage 1, the name, size and address of each school in the region was obtained and schools to be included in the sample were randomly selected. In stage 2, the required number of school children was drawn. By using this figure, the sizes of the different schools and the required sample sizes, the number of children per school, to be included in the sample, was calculated. 3.1.2 SAMPLE SIZE AND REPRESENTATION The sample consists of 12-year-old children attending sixth and seventh year primary schools. Age was considered according to the last birthday giving an age range from 12 years 0 months to 12 years 11 months (32). No exclusion criteria regarding occlusion were adopted in the selection of the sample so that the sample can be a true representation of the target population. Six governorates were randomly selected for examination. The governorates are Sana’a, Hadhrmot, Aden, Taiz, Hoddeidah and Ibb. 57 Chapter two Material & methods In each governorate the same multi-stage stratified sampling technique was implemented. From each sector 500 children were included in the survey, half of whom (250 Children) were urban and the other half were rural. Urban children were considered as those living in the center of each governorate taken as clusters of 25 students from 10 randomly selected schools. Rural children were selected from five small villages from each sector, two clusters of 25 students from each village. This gives a total of 3000 examined children taken from 120 schools; half of whom were males (1500 students from 60 schools) and the other half were females 1500 students from 60 schools). The number of children examined was increased more than planned to adjust for those isolated because of history or currently undergoing orthodontic treatment or undergone extraction of permanent teeth to improve appearance. From each school the first accessible 25 children were examined and then we move to another school. Thirteen schools did not have 25 children 12-years of age so neighboring schools were visited to complete the required number making the total number of visited schools 133. Permission was obtained from the general directorate of education in Yemen and the regional directorate of education in the governorates. All school authorities were contacted and the purpose of the study was explained to them to ensure full cooperation. 58 Chapter two Material & methods A total of 3127 students were examined; from which 56 case sheets 1.8% were excluded because of incomplete or inaccurate information giving a valid sample of 3071. The population of the six selected governorates was more than 42.0% of the population of Yemen, and they contained 53.3% of the 12-year old intermediate school children 50.3% of the boys and 58.4% of the girls (Table 3-1). Since there were 224,562 primary school students aged 12 years in these six governorates in the year 2004, so the sample (3071 children) represents 1.4% of the target population; 1.1% of the boys and 1.7% of the girls. Table 3-1: The size of the realized sample for the 12-year-old group. Governorate 12 year olds students Males Females Total Total population Aden 6,184 5,141 11,325 539,822 Hadhrmot 11,483 5,353 16,836 910,246 Hoddiedah 22,210 12,598 34,808 2,034,049 Ibb 35,644 19,172 54,816 2,216,139 Sana’a 20,624 17,533 38,157 1,735,571 Taiz 40,680 27,940 68,620 2,538,486 Total 136,825 87,737 224,562 7,952,264 All Yemen 271,438 150,229 421,667 59 18,853,000 Chapter two 3.2 Material & methods INSTRUMENTS, EQUIPMENT AND CONSUMABLES The following instruments equipment and material were used in the survey: • Periodontal probe - The WHO 621 periodontal probe was used. • Mouth mirror - An ordinary mouth mirror (No 4) (Derfla, West Germany) was used. • Millimeter graded vernier (Inox, Zurcher Modell, Dentaurum 042-751). • Metric ruler. • Stationery - A clipboard, pencil, sharpener and an eraser were used. • Consumables – Disinfecting agents, papertowels, rubber gloves, facemasks. • Equipment - Portable lights, autoclaves and suitable receptacles for the return of used instruments. 3.3 METHOD 3.3.1 EXAMINATION AREA: The children examined were seated in a chair with a high backrest with their head supported in an upright position and the examiner standing in front of the chair (32, 66) . Whenever possible the examination area was partitioned or arranged in such away that children enter at one point and leave at another. The children 60 Chapter two Material & methods were not permitted to crowd around the examiner. Daylight was used for illumination, and a portable light was used to supplement natural daylight during examination when needed. In the absence of electricity the portable light was connected to a 12V battery. Every day case sheets were reviewed to ensure accuracy of recording, a tap record was used for double checking. 3.3.2 QUESTIONNAIRE: Before any dental examination was done, the date of examination, governorate, location, schools name, school class and gender of the children was registered. Later each child was interviewed individually to obtain first demographic information regarding their name and birth date (Appendix 1). The children were asked some questions regarding his/ her perception of occlusion. This questionnaire was modified from Ng’ang’a et al. (199) and Ingervall et al. (202) as shown in (Appendix 2). The questionnaire included: 1. Do you find that your teeth are irregular (not straight) or come together in a wrong way? a) Yes, b) No, c) Do not know 2. If yes, do you think that your teeth are: a) crowded, b) spaced, c) protruded, displaced. 61 d) rotated or Chapter two Material & methods 3. If your teeth are irregular, does this affect your: a) appearance, b) chewing or mastication, or c) speech and pronunciation. 4. If you think you need orthodontic treatment, why have you not done so yet, is it because you think that its treatment is: a) not possible, b) expensive, c) painful, d) not important, or e) another reason (mention it). The children with signs of orthodontic treatment were also asked about any previous history of orthodontic treatment: 1. Have you ever had orthodontic treatment in the past (describe the type of treatment)? 2. Are you currently under orthodontic treatment (describe type of treatment and appliance)? 3. Has any of your teeth been extracted to improve appearance (which one(s))? 3.4 CLINICAL EXAMINATION: Before the intraoral clinical examination was commenced, gross anomalies, cleft lip and/or palate, traumatic or surgical defects were noted and described in the notes section (Appendix 1). According to the Dental Aesthetic Index (32, 78) the intraoral examination (Appendix 3) included the objective registration of the occlusal features which is divided into two parts: 62 Chapter two Material & methods I- Intra-arch irregularities and malalignment 1. Missing visible teeth: 2. Crowding in the incisal segments of the arch. 3. Spacing in the incisal segments of the arch. 4. Maxillary central diastema. 5. Largest anterior irregularity on the maxillary arch. 6. Largest anterior irregularity on the mandibular arch. II- Discrepancies in occlusal contact relationship 1. Anterior maxillary overjet. 2. Anterior mandibular overjet (negative overjet). 3. Vertical anterior openbite. 4. Antero-posterior molar relation. 3.4.1 INTRA-ARCH IRREGULARITIES AND MALALIGNMENT 1. MISSING VISIBLE TEETH: This is the number of missing permanent incisor, canine and premolar teeth in the upper and lower arches. This was done by counting the teeth present starting at the right second premolar moving forward to the left second premolar. A history of all missing anterior teeth was obtained to determine whether extractions were performed for aesthetic reasons. Teeth were not recorded as missing if spaces were closed, if a primary tooth was still in position and its successor has not yet erupted, or if a missing incisor, canine or premolar tooth has been replaced by a fixed prosthesis. 63 Chapter two Material & methods 2. CROWDING IN THE INCISAL SEGMENTS OF THE ARCH: Both maxillary and mandibular incisal segments were examined for crowding. Crowding in the incisal segment was the condition in which the available space between the right and left canine teeth was insufficient to accommodate all four incisors in normal alignment. Teeth may be rotated or displaced out of alignment in the arch (Figure 3-1). The number of incisor segments (each incisal segments consists of four incisors in either the maxillary or mandibular arch) with crowding was recorded as: 0 (no segment crowded), 1 (1 segment crowded), or 2 (2 segments crowded). When in doubt the lower score was assigned. If the four incisors were in proper alignment but either or both canines were displaced, the incisal segment was not marked as crowded. Figure 3-1: Examples of anterior intra-arch irregularities. 64 Chapter two Material & methods 3. SPACING IN THE INCISAL SEGMENTS OF THE ARCH: Spacing is the condition in which the amount of space available between the right and left canine teeth exceeds that required to accommodate all four incisors in normal alignment. If one or more incisor teeth have proximal surfaces without any interdental contact, the segment was recorded as having space. Both the upper and lower incisal segments were examined for spacing. The space from a recently exfoliated primary tooth was not recorded if it appears that the permanent replacement will soon erupt. The number of incisal segments in both arches with spacing was recorded as either: 0, 1 or 2. When in doubt the lower score was assigned. 4. MAXILLARY CENTRAL DIASTEMA: A diastema is defined as a space greater than 0.5 millimeters between the proximal surfaces of adjacent teeth; a midline diastema indicates a space between the central incisors.2, 238 The measurement was recorded at any level between the mesial surfaces of the central incisors to the nearest whole millimeter. 65 Chapter two 5. LARGEST Material & methods ANTERIOR IRREGULARITY ON THE MAXILLARY ARCH: Irregularities may either be rotations out or displacements from, normal alignment (Figure 3-1). The four incisors were visually scanned to locate the greatest irregularity between adjacent teeth and it was measured using a metric ruler to the nearest whole millimeter. Irregularities may occur with or without crowding. If there was a sufficient space for all four incisors in normal alignment but some were rotated or displaced that segment was not be marked as crowded, only the largest irregularity was recorded. 6. LARGEST ANTERIOR IRREGULARITY ON THE MANDIBULAR ARCH: This measurement was the same as on the maxillary arch except that it was done on the mandibular arch. The greatest irregularity between adjacent teeth on the mandibular arch was located and measured as described before (Figure 3-2). Figure 3-2: Measuring irregularities with a metric ruler or vernier. 66 Chapter two Material & methods 3.4.2 DISCREPANCIES IN OCCLUSAL CONTACT RELATIONSHIP 1. ANTERIOR MAXILLARY OVERJET: Anterior maxillary overjet is the measurement of the horizontal relation of the incisors with the teeth in centric occlusion. The distance from the labial-incisal edge of the most prominent upper incisor to the labial surface of the corresponding lower incisor was measured. Maxillary overjet was not recorded where all the upper incisors were missing or in lingual crossbite. If the incisors occlude edge to edge, the overjet was scored as zero. The largest maxillary overjet was recorded with a metal ruler or vernier to the nearest whole millimeter. 2. ANTERIOR MANDIBULAR OVERJET: This trait was recorded when any mandibular incisor protruded labially to the opposing maxillary incisor (inverted). The largest negative overjet of any of the incisors in the mandibular arch was recorded to the nearest whole millimeter. If a mandibular incisor was rotated so that one part of the incisal edge was in crossbite (was labial to the maxillary incisor) but another part of the incisal edge was not in crossbite negative overjet was not measured. 3. VERTICAL ANTERIOR OPENBITE: Anterior openbite is a lack of vertical overlap between any of the opposing pairs of incisors (openbite). Anterior openbite reflects discrepancies in the vertical plane of space (238). 67 Chapter two Material & methods The largest lack of vertical overlap between the opposing pairs of incisors was recorded to the nearest whole millimeter. 4. ANTERO-POSTERIOR MOLAR RELATION: This assessment most often was based on the relation of the permanent maxillary and mandibular first molars. If the assessment cannot be based on the first molars because one or both were absent, not fully erupted, or misshaped because of extensive decay or fillings, the relations of the permanent canines and premolars are assessed. The right and left sides were assessed with the teeth in occlusion as described in (Figure 3-3) and only the side with the largest deviation from normal molar relation was recorded. The score was as follows: 0= Normal molar relation 1= Mandibular first molar on either side is half cusp either mesial or distal to the maxillary first molar 2 = Mandibular first molar on either side is one full cusp or more either mesial or distal to the maxillary first molar when in doubt the lower score was assigned. Figure 3-3: Classification or molar relation 68 Chapter two Material & methods 3.5 INDEX FOR TREATMENT NEED ASSESSMENTS The Dental Aesthetic Index (DAI), used in this study to investigate orthodontic treatment need, is an orthodontic index that links clinical and aesthetic components mathematically to produce a single score that combines the physical and aesthetic aspects of occlusion. The DAI is an equation or formula in which ten measured components are multiplied by their regression coefficients (weights). The addition of their products and the addition of a constant number ‘13’ to the total gives the DAI score as shown in (Appendix 3). The following hypothetical case illustrates the calculation of a DAI score using rounded regression coefficient (weights). Traits present in the hypothetical case include: Crowding - mandibular incisal segment only Largest irregularity in maxilla is 3mm Largest irregularity in mandible is 2mm Maxillary overjet is 7mm Score 1 x 1 Score 3 x 1 Score 2 x 1 Score 7x2 Molar relation is one full cusp Add the constant number ‘13’ to the total Score 2 x 3 1 3 2 14 6 13 39 The total is the DAI score After the child’s scores were calculated, they were rankordered on a continuous scale from 13 and above. The higher the DAI score, the more likely the occlusal condition is both socially and physically handicapping. 69 Chapter two Material & methods 3.6 INFECTION CONTROL The only method used for the sterilization of the periodontal probes and mouth mirrors was by autoclaving. A large number of CPI-type probes were made available in each examination area to enable proper sterilization. For the protection of the examiner and patients, the use of disposable gloves and surgical masks was used throughout the survey. 3.7 CALIBRATION AND TRAINING Before the pilot study was started inter-examiner and intraexaminer calibration was done to ensure consistent application of the diagnostic criteria. Inter-examiner calibration was done with well experienced orthodontists on thirty- five pre-orthodontic patients attending private clinics. Orthodontic patients selected because they presented various types of occlusal anomalies. Intraexaminer calibration was carried out by re-examination after two weeks to eliminate the chance of memory bias. The results of intra- and inter-examiner calibration of parametric data using paired t-test showed a statistically insignificant difference (Table 3-2). Also, intra- and inter-examiner calibration of non-parametric data showed very high percentages of agreement (Table 3-3). The previous questionnaire and definitions of the various malocclusion features and of the need for orthodontic treatment used in this investigation have been used and tested in a pilot study on 400 primary school students aged 12-13 year in Sana'a 70 Chapter two Material & methods City in October 2003, and modified in the light of experience derived from the pilot study. 3.8 STATISTICAL ANALYSIS Entering of data and its analysis was carried out using SPSS 13 program on a Pentium III personal computer. This included the following: 1. Classification of data and calculation of frequencies for nonparametric variables. 2. Cross-tabulation of the variables with gender, governorate and residency. 3. Calculation of statistical parameters for parametric variables. 4. Analysis of the parametric variables by ANOVA and Student ttests. A standard DAI score was calculated for each child in the twelve-year-old age group by using the formula as explained in Chapter 2. The children were classified into four groups according to the severity of malocclusion and treatment need as measured by the standard DAI score. A p-value of less than 0.05 indicates that the variables in that particular interaction term differ significantly. 71 Chapter two Material & methods Table 3-2: Intra- and inter-examiner calibration of parametric data using paired t-test. Variable Intra-examiner Inter- examiner calibration calibration t df P level t df P level 0.50 34 NS 0.512 34 NS 0.314 34 NS 0.543 34 NS 0.562 34 NS 0.786 34 NS 0.489 34 NS 0.598 34 NS Maxillary overjet 0.123 34 NS 0.193 34 NS Mandibular overjet 0.312 34 NS 0.393 34 NS Vertical anterior openbite 0.703 34 NS 0.815 34 NS Number of missing visible teeth Maxillary central diastema Largest anterior irregularity (maxillary) Largest anterior irregularity (mandibular) Table 3-3: Intra- and inter-examiner calibration of non-parametric data using percentage of agreement. Intra-examiner Inter-examiner calibration calibration Crowded segments 97.5% 98.3% Spaced segments 98.3% 99.2% Molar occlusion 98.9% 99.2% Variable 72 Chapter three Results RESULTS 4.1 THE SAMPLE The total number of examined Children was 3127; from which 56 case sheets were excluded because of incomplete or inaccurate information or incorrect age, giving a valid sample of 3071 (Tables 4-1 and 4-2). After isolating the Children with history of, or presently undergoing orthodontic treatment and those who have undergone extraction of permanent teeth to improve appearance, the number of case sheets which entered the statistical analysis in this chapter dropped to 3003. Distribution of the examined Children according to history of orthodontic treatment whether in the past, present or just extraction of permanent teeth to improve appearance are shown in (Tables 4-3, 4-4 and 4-5) according to governorate, gender and residency. Twenty seven Children 0.9% did or are doing orthodontic treatment, mostly from Sana'a 2.5% and Aden 1.2%, and least in Hadhrmot 0.0%. This difference in governorates was statistically significant (X2= 57.533, df = 5, p<0.05). Females showed more orthodontic treatment 1.3% than males 0.5% which was statistically significant (X2= 12.278, df = 1, p<0.05). 73 Chapter three Results The children who had undergone extractions to improve appearance were 1.3% mostly from Taiz 1.5% and Sana'a 1.3%. This difference in governorates was statistically significant (X2= 61.686, df = 5, p<0.05). Females showed statistically insignificant difference in extractions than males (X2= 0.055, df = 1, P>0.05). Orthodontic extractions were found to be more in the urbans 2.1% than rural population 0.6%. This difference was statistically significant (X2= 63.472, df = 1, p<0.05). Sana'a Taiz Total Total Ibb Rural Hoddiedah Urban Males 129 128 130 127 135 130 779 Females 131 129 133 127 140 132 792 Total 260 257 263 254 175 162 1571 Males 128 128 128 127 132 131 774 Females 130 126 131 128 135 132 782 Total 258 254 259 255 267 263 1556 Males 257 256 258 254 267 261 1553 Females 261 255 264 255 275 264 1574 Total 518 511 522 509 542 525 3127 Gender Aden Location Hadhrmot Table 4-1: Number and distribution of all the examined children. 74 Chapter three Results Sana'a Taiz Total Total Ibb Rural Hoddiedah Urban Males 127 125 130 125 133 128 768 Females 130 127 129 127 136 131 780 Total 257 252 259 252 269 259 1548 Males 125 125 125 126 127 130 758 Females 129 125 125 126 131 129 765 Total 254 250 259 252 258 259 1523 Males 252 250 255 251 260 259 1524 Females 259 252 264 253 267 259 1549 Total 511 502 509 504 527 518 3071 Gender Aden Location Hadhrmot Table 4-2: Number and distribution of valid case sheets. Table 4-3: Distribution of the examined children according to history of orthodontic treatment by governorate. Aden n % Hadhrmot N % Hoddiedah n % n Ibb % Sana'a n % n Taiz % Total n % Done or doing orthodontic treatment 6 1.2 0 0 3 0.6 1 0.2 13 2.5 4 0.8 27 0.9 5 1.0 2 0.4 6 1.2 3 0.6 11 2.1 14 2.7 41 1.3 500 97.8 500 99.6 500 98.2 500 99.2 503 95.4 500 96.5 3003 97.8 511 100 502 100 509 100 504 100 527 100 518 100 3071 100 Extracted teeth to improve appearance No orthodontic treatment Total 75 Chapter three Results Table 4-4: Distribution of the examined children according to history of orthodontic treatment by gender. Male n % Female n % Total n % Done or doing orthodontic treatment 7 0.5 20 1.3 27 0.9 Extracted teeth to improve appearance 18 1.2 23 1.5 41 1.3 No orthodontic treatment 1502 98.3 1501 97.2 3003 97.8 Total 1527 100 1544 100 3071 100 Table 4-5: Distribution of the examined children according to history of orthodontic treatment by residency. Urban n % Rural n % Total n % Done or doing orthodontic treatment 24 1.5 3 0.2 27 0.9 Extracted teeth to improve appearance 32 2.1 9 0.6 41 1.3 No orthodontic treatment 1502 96.4 1501 99.2 3003 97.8 Total 1558 100 1513 100 3071 100 76 Chapter three Results 4.2 QUESTIONNAIRE: 4.2.1 QUESTION 1 (TEETH ALIGNMENT): Regarding the answers to the first question concerned with the self-evaluation of the children to the alignment of their teeth, 892 children 29.7% answered that they have malaligned teeth, 1904 children 63.4% said that they have aligned teeth and 207 students 6.9% chose the option 'don't know' (Table 4-6) Children who thought that they have malaligned teeth predominated in Sana'a 34.6% and were least in Hadhrmot 25.1%. This difference was statistically significant (X2= 104.229, df = 5, p<0.05). On the other hand, children who answered 'don't know' were distributed, in the opposite manner, being mostly in Hadhrmot (8.2%) and least in Sana'a 5.7% (Table 4-6). Females reported that they have malaligned teeth 34.6% more than males 24.8%, this results was statistically significant (X2= 50.802, df = 1, p<0.05) (Table 4-7). Considering residency differences, statistically insignificant difference were reported between urban and rural children who thought that they have malaligned teeth (Table 4-8). In the coming three questions (Tables 4-9 - 4-17) the percentages given are from those who think that they have malaligned teeth who are 892 students (29.7% from the total sample). Also, the summation of the numbers is more than the total because some students chose more than one option. 77 Chapter three Results Table 4-6: Distribution of the answers to question 1 regarding the alignment of the children teeth by governorate. Aden Hadhramot Hoddiedah Ibb Sana'a Taiz Total n % n % n % n % n % n % n % Aligned 303 60.7 334 66.7 326 65.2 325 64.9 300 59.7 316 63.1 1904 63.4 Malaligned 165 32.9 125 25.1 136 27.2 143 28.6 174 34.6 149 29.8 892 29.7 Don't know 32 6.4 41 8.2 38 7.6 32 6.5 29 5.7 35 7.1 207 6.9 Total 500 100 500 100 500 100 500 100 503 100 500 100 3003 100 Table 4-7: Distribution of the answers to question 1 regarding the alignment of the children teeth by gender. Male n % Aligned 1020 67.9 Female n % Total N % 884 58.9 1904 63.4 Malaligned 373 24.8 519 34.6 892 29.7 Don't know 109 7.3 98 6.5 207 6.9 Total 1502 100 1501 78 100 3003 100 Chapter three Results Table 4-8: Distribution of the answers to question 1 regarding the alignment of the children teeth by residency. Urban n % Rural n % Total n % Aligned 907 60.4 970 64.7 1904 63.4 Malaligned 469 31.2 423 28.2 892 29.7 Don't know 99 6.7 108 7.2 207 6.9 Total 1502 100 1501 100 3003 100 4.2.2 QUESTION 2 (TYPE OF MALALIGNMENT): Regarding the answers to the second question concerned with the type of malaligned teeth, the distribution of the children according to what they thought was: 287 children 32.2% had crowded teeth, 139 students 15.6% had spaced teeth, 260 children 29.1% had protruded teeth and 224 children 25.1% had rotated and displaced teeth (Table 4-9). Statistical significant difference was found between the governorates (X2= 40.453, df = 15,. p<0.05) as shown in (Table 4-9); in which crowded teeth were mostly found in Taiz 39.1.0% and least in Hadhrmot 25.7%, spaced teeth were mostly found in Ibb 18.3% and least in Sana'a 13.4%, protruded teeth were mostly found in Hoddiedah 34.6% and least in Taiz 22.1% and rotated and displaced teeth were mostly found in Aden 27.3% and least in Ibb 17.6%. 79 Chapter three Results Considering gender differences, statistically insignificant difference was reported between males and females children who thought that they have malaligned teeth (Table 4-10). Also, an insignificant difference was found between urbans and rurals children (X2= 5.151, df = 1, p>0.05) as shown in (Table 4-11). Table 4-9: Distribution of the answers to question 2 regarding the type of malalignment of teeth by governorate. Aden n=165 Hadhramot n=125 Hoddiedah n=136 Ibb n=143 Sana'a n=174 Taiz n=149 Total n=892 n % n % n % n % n % n % n % Crowded 55 33.3 32 25.7 39 28.8 42 29.6 61 35.3 58 39.1 287 32.2 Spaced 24 14.3 19 14.9 25 18.3 24 16.8 27 13.4 20 13.5 139 15.6 Protruded 43 26.3 42 33.7 47 34.6 44 30.8 51 29.3 33 22.1 260 29.1 Rotated and displaced 48 29.1 34 27.1 28 20.6 28 19.6 45 25.9 41 27.5 224 25.1 Table 4-10: Distribution of the answers to question 2 regarding the type of malalignment of teeth by gender. Male n=373 n % Female n=519 n % Total n=892 n % Crowded 121 32.4 166 32.0 287 32.2 Spaced 56 15.0 88 17.0 139 15.6 Protruded 112 30.0 150 28.9 260 29.1 Rotated and displaced 93 24.9 122 23.5 224 25.1 80 Chapter three Results Table 4-11: Distribution of the answers to question 2 regarding the type of malalignment of teeth by residency. Urban n=469 n % Rural n=423 n % Total n=892 n % Crowded 150 32.0 137 32.4 287 32.2 Spaced 72 15.4 67 15.8 139 15.6 Protruded 142 30.3 118 27.9 260 29.1 Rotated and displaced 113 24.1 111 26.2 224 25.1 4.2.3 QUESTION 3 (EFFECT OF MALALIGNMENT): Of the 892 children who stated that they have malaligned teeth, 547 children 61.3% thought that it affected their appearance, 61 children 6.8% affected chewing and 69 children 7.7% affected speech, while 222 children 24.9% answered that malaligned teeth did not affect appearance, chewing or speech (Table 4-12). Appearance was the highest concern in Sana'a 67.2% and Aden 66.1% and least in Hoddiedah 56.6%. However, those who reported that their malocclusion has no effect have a reverse distribution in which Hadhrmot showed the highest percentage 28.0%, then Hoddiedah 27.9% and Taiz 26.2%, and was lowest in Sana'a 21.4% and Aden 22.4%. These differences were statistically significant (X2= 25.804, df = 15, p<0.001) as shown in (Table 4-12). 81 Chapter three Results Concerning gender differences, females answered more to 'affect appearance' and less to 'no effect' than males, but this was statistically insignificant (X2= 1.752, df = 3, P>0.05) (Table 4-13). The urbans answered more to 'affect appearance' and less to 'no effect' than the rurals. This was statistically significant (X2= 20.692, df = 3, p<0.05) (Table 4-14). Table 4-12: Distribution of the answers to question 3 regarding the effect of malalignment of teeth by governorate. Aden n=165 Hadhramot Hoddiedah n=125 N=136 Ibb n=143 Sana'a n=174 Taiz n=149 Total n=892 n % n % N % n % n % n % n % Appearance 109 66.1 72 57.6 77 56.6 85 59.4 117 67.2 87 58.4 547 61.3 Chewing 10 6.1 8 6.4 13 9.6 10 7.0 11 6.3 9 6.0 61 6.8 Speech 12 6.8 8 6.6 11 7.7 12 8.4 13 7.5 13 8.5 69 7.7 No effect 37 22.4 35 28.0 38 27.9 36 25.3 37 21.4 39 26.2 222 24.9 Table 4-13: Distribution of the answers to question 3 regarding the effect of malalignment of teeth by gender. Male n=373 n % Female n=519 n % Total n=892 n % Appearance 223 59.8 324 62.4 547 61.3 Chewing 26 7.0 35 6.6 61 6.8 Speech 29 7.8 40 7.7 69 7.7 No effect 97 26.0 125 24.1 222 24.9 82 Chapter three Results Table 4-14: Distribution of the answers to question 3 regarding the effect of malalignment of teeth by residency. Urban n=469 n % Rural n=423 n % Total n=892 n % Appearance 297 63.3 250 59.1 547 61.3 Chewing 26 5.5 35 8.3 61 6.8 Speech 37 7.9 32 7.6 69 7.7 No effect 114 24.3 108 25.5 222 24.9 3.2.4 QUESTION 4 (SEEKING TREATMENT): When these children were asked why they did not seek orthodontic treatment in spite of their belief that they had malaligned teeth: 27.3% did not know, 17.6% said that treatment is not important, 16.9% thought that treatment is not possible, 14.4% feared pain, and 9.3% feared extraction of teeth. Other less popular reasons included: hope for spontaneous improvement 6.4%, treatment is expensive 4.4%, no time for treatment 2.5%, poor esthetics of appliances 1.1%, postponed by the dentist 0.5%, difficult to get used to orthodontic appliances 0.4%, and fear of cross contamination 0.2%. Children from Sana'a and Aden answered the fear of pain, fear of extraction, treatment is expensive, postponed by the dentist, no time for treatment, fear of cross contamination, difficult to get used to it and poor esthetics of appliances more than the children from the other governorates (Table 4-15). On 83 Chapter three Results the other hand, children from Hadhrmot, Ibb, Hoddiedah and Taiz answered that treatment is not important or not possible, hope for spontaneous improvement, and don't know more than the students from Sana'a and Aden. This was statistically significant (X2= 182.095, df = 40, p<0.05). Female answered that fear of pain, fear of extraction, postponed by the dentist, fear of cross-contamination, difficult to get used to it and poor esthetics of appliances more than the male, while male answered to treatment is not important or expensive, hope for spontaneous improvement more than the female (Table 4-16). This was statistically significant (X2= 22.577, df = 9, p<0.05) Statistically insignificant differences were found between female and male those answered to treatment is not possible, no time for treatment and don't know. Urban children answered that postponed by the dentist and fear of cross-contamination more than rural students, while rural children answered to treatment is not important or not possible, no time for treatment, hope for spontaneous improvement, and difficult to get used to it more than urban children (Table 4-17). This was statistically significant for the male sample (X2= 43.482, df = 9, p<0.05). Statistically insignificant differences were found between urban and rural children who answered that treatment is not possible, fear of pain and extraction, poor esthetics of appliances and don't know. 84 Chapter three Results Table 4-15: Distribution of the answers to question 4 regarding the reason for not seeking treatment by governorate. Aden n=165 Hadhramot Hoddiedah n=125 n=136 Ibb n=143 Sana'a n=174 Taiz n=149 Total n=892 n % n % n % n % n % N % n % Treatment is not important 26 16.0 24 19.2 30 21.8 27 19.0 22 12.7 28 18.7 157 17.6 Treatment is not possible 27 16.6 23 18.4 25 18.6 24 16.8 22 12.7 30 20.4 151 16.9 Fear of pain 33 19.8 12 9.6 15 11.0 18 12.6 35 20.0 15 9.9 128 14.4 Fear of extraction 18 11.1 8 6.4 9 6.6 12 8.4 22 12.7 14 9.4 83 9.3 Treatment is expensive 9 5.7 6 4.6 6 4.4 4 2.8 9 5.2 5 3.2 39 4.4 Postponed by dentist 2 1.4 0 0.0 0 0.0 0 0.0 3 1.7 0.0 0.0 5 0.5 No time for treatment 6 3.7 0 0.0 0 0.0 4 2.8 10 5.7 2 1.3 22 2.5 Fear of cross-contamination 1 0.6 0 0.0 0 0.0 0 0.0 1 0.6 0 0.0 2 0.2 Hope for spontaneous improvement 8 4.9 11 8.8 10 7.4 9 6.3 9 5.2 10 6.7 57 6.4 Difficult to get used it 3 1.8 0 0.0 0 0.0 0 0.0 1 0.6 0 0.0 4 0.4 Poor esthetic of appliances 3 1.8 0 0.0 0 0.0 1 0.7 4 2.3 2 1.3 10 1.1 31 18.8 43 34.4 42 31.2 46 32.2 37 21.3 45 30.1 244 27.3 Don't know 85 Chapter three Results Table 4-16: Distribution of the answers to question 4 regarding the reason for not seeking treatment by gender. Male n=373 n % Female n=519 n % Total n=892 n % Treatment is not important 75 20.1 82 15.7 157 17.6 Treatment is not possible 61 16.4 90 17.4 151 16.9 Fear of pain 46 12.3 82 15.7 128 14.4 Fear of extraction 29 7.8 54 10.3 83 9.3 Treatment is expensive 23 6.1 16 3.4 39 4.4 Postponed by dentist 1 0.3 4 0.8 5 0.5 No time for treatment 10 2.7 12 2.3 22 2.5 0 0.0 2 0.4 2 0.2 Hope for spontaneous improvement 27 7.2 30 5.8 57 6.4 Difficult to get used it 1 0.3 3 0.6 4 0.4 Poor esthetic of appliances 3 0.8 7 1.3 10 1.1 101 27.1 143 Fear of cross-contamination Don't know 86 27.6 244 27.3 Chapter three Results Table 4-17: Distribution of the answers to question 4 regarding the reason for not seeking treatment by residency. Urban n=469 n % Rural n=423 n % Total n=892 n % Treatment is not important 78 16.6 79 18.7 157 17.6 Treatment is not possible 81 17.3 70 16.5 151 16.9 Fear of pain 67 14.3 61 14.4 128 14.4 Fear of extraction 45 9.5 38 9.0 83 9.3 Treatment is expensive 21 4.5 18 4.3 39 4.4 Postponed by dentist 5 1.1 0 0.0 5 0.5 No time for treatment 10 2.0 12 2.9 22 2.5 2 0.4 0 0.0 2 0.2 Hope for spontaneous improvement 28 6.0 29 6.9 57 6.4 Difficult to get used it 1 0.2 3 0.7 4 0.4 Poor esthetic of appliances 7 1.5 3 0.7 10 1.1 129 27.5 114 27.2 Fear of cross-contamination Don't know 87 244 27.3 Chapter three Results 4.3 COMPOSITION OF THE SAMPLE IN TERMS OF DENTITION STAGE 4.3.1 THE PREVALENCE OF DENTITION STAGE The prevalence of the late mixed dentition stage and early permanent dentition stage in the different governorates of Yemen is shown in (Figure 4-1). Division of the sample in the late mixed dentition stage and early dentition stage indicated that 26.1% of the study population ere still in the late mixed dentition stage and 73.9% presented with a dentition in the early permanent stage. Figure 4-1: The percentage distribution of the late mixed dentition stage and early permanent dentition stage for the total sample. Late mixed dentition Early permanent dentition % 80 73.9 70 60 50 40 26.1 30 20 10 0 88 Chapter three Results 4.3.2 THE PREVALENCE OF DENTITION STAGE BY GENDER Gender differences for the prevalence of the late mixed dentition or the early permanent dentition stage in 12-year-old Yemeni school children are shown in (Table 4-18). The results indicated that there are more 12- year-old girls presenting with a dentition in the early permanent stage than boys, 77.6% and 70.1% respectively. The distribution of the number of males and females in the two stages of dental development was statistically significant different (p<0.05). Table 4-18: The percentage distribution of dentition stage by gender. Gender Late mixed dentition Early permanent dentition Male 29.9 70.1 Female 22.4 77.6 p<0.05 4.4 ANALYSIS OF THE DIFFERENT VARIABLES OF THE DAI 4.4.1 INTRA-ARCH IRREGULARITIES AND MALALIGNMENT 4.4.1.1 Missing maxillary and mandibular incisors, canines and premolars Two hundred and thirty eight children 7.9 % of the sample were found to have one or more missing incisors, canines and premolars, of whom 186 children 6.2 % involved one tooth, 44 children 1.5 % involved two teeth, while only 8 children 0.3 % involved three teeth (Figure 4-2). 89 Chapter three Results For the females 7.0% presented with only one tooth missing and 2.1% presented with two to three teeth missing. For the males 5.4% presented with one tooth missing and 1.3% presented with two to three missing teeth. Figure 4-2: Distribution of missing maxillary and mandibular incisors, canines and premolars by gender. 1 %10 9 8 7 6 5 4 3 2 1 0 2 0.3 1.8 0.2 1.1 7 Female 5.4 Male 3 0.3 1.5 6.2 Total Considering gender differences, females showed more missing maxillary and mandibular incisors, canines and premolars than males (both prevalence and mean) as shown in (Table 4-19). This was statistically significant (t= 2.493, df =3001, p<0.05) 90 Chapter three Results Table 4-19: Percentage and frequency distribution of missing maxillary and mandibular incisors, canines and premolars by gender. Number of missing teeth Female Male Frequency % Frequency % No missing teeth present 1364 89.7 1401 96.3 Missing teeth present 137 9.1 101 6.7 Mean 0.115 0.082 Std. error 0.010 0.008 Rurals showed more prevalence of missing maxillary and mandibular incisors, canines and premolars than urbans, but the mean was much alike as shown in (Table 4-20). These were statistically insignificant (t=-0.005, df =3001, P>0.05). For the urban 5.9% presented with only one tooth missing and 1.9% presented with two to three teeth missing. For the rural 6.4% presented with one tooth missing and 1.6% presented with two to three missing teeth. 91 Chapter three Results Table 4-20: Percentage and frequency distribution of missing maxillary and mandibular incisors, canines and premolars by residency. Number of missing teeth Urban Rural Frequency % Frequency % No missing teeth present 1385 92.2 1380 91.9 Missing teeth present 117 7.8 121 8.1 1 tooth missing 89 5.9 97 6.4 2 teeth missing 24 1.6 20 1.3 3 teeth missing 4 0.3 4 0.3 Mean 0.099 0.099 Std. error 0.010 0.009 4.4.1.2 Crowding in the incisal segments The results of the present study indicated that 68.6% of the children presented with no crowding in the incisal segments, 20.5% presented with crowding in one segment and 10.9% presented with crowding in two segments as shown in (Figure 43). 92 Chapter three Results Figure 4-3: Distribution of incisal crowding for the total sample. 10.9% No crowding 68.6% 20.5% No crowding Crowding in one segment Crowding in two segment Considering gender differences, males showed statistically insignificant more crowding in the incisal segments than females (x2=1.705, df =2, P>0.05) as shown in (Table 4-21). Table 4-21: Prevalence of crowding in the incisal segments by gender. Gender Crowding in the incisal segments Female Frequency % Male Frequency % No crowding 1045 69.2 1013 67.4 Crowding in one segment 296 19.7 321 21.4 Crowding in two segment 160 10.7 168 11.2 Total 1501 P>0.05 93 1502 Chapter three Results Considering residency statistically significant differences, more the crowding urbans than showed the rurals (x2=21.056, df =2, p<0.05) as shown in (Table 4-22). For the urbans 23.2% presented with only crowding in one segment and 12.2% presented with crowding in two segments. For the rurals 17.9% presented with only crowding in one segment and 9.7% presented with crowding in two segments. Table 4-22: Prevalence of crowding in the incisal segments by residency. Residency Crowding in the incisal segments Urban Rural Frequency % Frequency % No crowding 971 64.6 1087 72.4 Crowding in one segment 348 23.2 269 17.9 Crowding in two segment 183 12.2 145 9.7 Total 1502 1501 P<0.05 The prevalence of crowding was higher in the late early permanent dentition stage than in the mixed dentition stage, but this difference was statistically insignificant (x2=0.993, df =2, P>0.05) as shown in (Table 4-23). 94 Chapter three Results Table 4-23: Prevalence of crowding in the incisal segments by dentition stage. Dentition stage Crowding in the incisal segments Late mixed Early permanent dentition dentition Frequency % Frequency % No crowding 544 69.3 1495 67.4 Crowding in one segment 156 19.9 475 21.4 Crowding in two segment 85 10.8 264 11.2 Total 785 2218 P>0.05 The prevalence of crowding differed significantly between the six governorates in which Taiz and Sana'a showed the highest prevalence, while Ibb and Hadhrmot showed the lowest prevalence as shown in (Table 4-24). Table 4-24: Percentage and frequency distribution of crowding by governorate. Crowding in the incisal segments Governorate Aden no. No crowding % 379 75.8 Hadhramot Hoddiedah no. % no. % 340 68.0 329 65.8 Ibb no. % Sana'a no. % Taiz no. % 365 73.0 331 65.8 314 62.8 Crowding in one segment 80 16.0 103 20.6 122 24.4 65 13.0 122 24.3 125 25.0 Crowding in two segment 41 8.2 57 11.4 49 9.8 70 14.0 Total 500 500 P<0.05 95 500 500 50 9.9 503 61 12.2 500 Chapter three Results 4.4.1.3 Spacing in the incisal segments Figure 4-4 shows the prevalence of incisor spacing, of the 3003 children examined, more than 24.3% of the children presented with spacing. Almost eighteen per cent of the children presented with excess space in only one segment and 6.4 per cent with excess space in the two incisor segments. Figure 4-4: The prevalence of incisor spacing for the total sample. Two segments spaced 6.4 No Spacing present 75.7 One segment spaced 17.9 No Spacing present Statistically One segment spaced insignificant gender Two segments spaced differences were found concerning the distribution of spacing, where females showed more spacing in the incisal segments than males (x2=4.801, df =2, P>0.05) as shown in (Table 4-25). 96 Chapter three Results Table 4-25: Prevalence of spacing in the incisal segments by gender. Spacing in the incisal segments Gender Female Male Frequency % Frequency % No Spacing 1114 74.2 1159 77.2 Spacing in one segment 278 18.5 259 17.9 Spacing in two segment 109 7.3 84 6.4 Total 1501 1502 P>0.05 Considering residency differences, the prevalence of spacing was higher in the rurals than in the urbans, but these differences were statistically insignificant (x2=5.725, df =2, P>0.05) as shown in (Table 4-26). For the urbans 16.5% presented with only spacing in one segment and 5.9% presented with spacing in two segments. For the rurals 19.3% presented with only spacing in one segment and 6.9% presented with spacing in two segments. 97 Chapter three Results Table 4-26: Prevalence of spacing in the incisal segments by residency. Residency Spacing in the incisal segments Urban Rural Frequency % Frequency % No Spacing 1165 77.6 1108 73.8 Spacing in one segment 248 16.5 289 19.3 Spacing in two segment 89 5.9 104 6.9 Total 1502 1501 P>0.05 Statistically insignificant differences were found concerning the distribution of spacing between the late mixed dentition stage and the early permanent dentition stage as shown in (Table 427). Table 4-27: Prevalence of spacing in the incisal segments by dentition stage. Dentition stage Spacing in the incisal segments Late mixed Early permanent dentition dentition Frequency % Frequency % No Spacing 590 75.2 1683 75.9 Spacing in one segment 143 18.2 394 17.8 Spacing in two segment 52 6.6 141 6.4 Total 785 P>0.05 98 2218 Chapter three Table Results 4-28 summarises the prevalence of spacing by governorate. Ibb and Taiz showed the highest prevalence of spacing, while Sana'a and Hoddiedah showed the lowest prevalence of spacing, but these differences were statistically insignificant. Table 4-28: Percentage and frequency distribution of spacing by governorate. Governorate Spacing in the incisal segments Aden Hadhramot Hoddiedah Ibb Sana'a n % n % n % n % n No Spacing 382 76.4 376 75.2 387 77.4 366 73.2 393 78.1 369 73.8 Spacing in one segment 79 15.8 99 19.8 81 16.2 99 19.8 79 15.7 100 20.0 Spacing in two segment 39 7.8 25 5.0 32 6.4 35 7.0 31 Total 500 500 500 P>0.05 99 500 % Taiz 6.2 503 n 31 % 6.2 500 Chapter three Results 4.4.1.4 Maxillary midline diastema Of the 3003 children examined, 426 or 14.2% presented with maxillary midline diastema (Figure 4-5). Figure 4-5: Prevalence of maxillary midline diastema in 12-year-old Yemeni school children. 14.2% 85.8% No diastema Diastema The size of the diastema ranged from 1 to 4 mm, the distribution of the severity of diastema in the affected groups is shown in (Table 4-29). Table 4-29: Percentage distribution of the severity of maxillary midline diastema in the affected group. Size Percentage distribution (%) 1 mm 8.1 2 mm 4.3 3 mm 1.4 4 mm 0.4 Total 14.2 100 Chapter three Results If spaces greater than 2 mm are taken into account, 1.8% of the children presented with diastema (Figure 4-6). Figure 4-6: Prevalence of diastema (>2 mm) in 12-year-old Yemeni school children. 1.8% <=2mm >2mm 98.2% Considering gender differences, diastema was found to be almost equally distributed between males and females as shown in (Table 4-30). Table 4-30: The prevalence of midline diastema by gender. Gender n No diastema (%) diastema (%) Male 1502 86.6 13.4 Female 1501 85.0 14.9 Total (%) 14.2 p>0.05 The differences between the two groups were statistically insignificant. 101 Chapter three Results If diastema larger than 2 mm is taken into account, the results show that about twice as many females 2.6% than males 1.3% presented with diastema (Table 4-31). The differences between the two groups were statistically significantly (p<0.05). The results indicate that there are more girls than boys with a midline diastema larger than 2 mm. Table 4-31: Gender distribution of diastema (>2mm) in 12-yearold Yemeni school children. Gender Midline diastema % Male > 2 mm 1.3 Female > 2 mm 2.6 P<0.05 The distribution of midline diastema and midline diastema larger than 2 mm in the late mixed and early permanent dentition is shown in (Table 4-32). Table 4-32: Percentage distribution of midline diastema and midline diastema >2 mm in the affected group. Dentition stage Midline diastema Midline diastema> 2 mm Late mixed dentition 14.5 % 2.1 % 13.9 % 1.7 % Early permanent dentition 102 Chapter three Results The results for the interaction of dentition stage and midline diastema and midline diastema larger than 2 mm indicated that midline diastema is more prevalent in the late mixed dentition than in the early permanent dentition. The percentage distribution of midline diastema by governorate is shown in (Table 4-33). Taiz showed the highest prevalence of maxillary midline diastema 15.8% followed by Hoddiedah 14.8%, while Aden showed the lowest prevalence of maxillary midline diastema 12.4%, but these differences were statistically insignificant. Table 4-33: Percentage and frequency distribution of diastema by governorate. Governorate Diastema Aden n % No diastema 438 87.6 Diastema 62 12.4 Hadhramot Hoddiedah Ibb n % n % n 433 86.6 426 85.2 429 67 13.4 74 14.8 71 Sana'a % n Taiz % n % 85.8 430 85.5 421 84.2 14.2 14.0 79 15.8 70 P>0.05 The mean maxillary midline diastema width was 0.23 mm. Figure 4-7 show the mean diastema width according to governorate. 103 Chapter three Results Figure 4-7: Mean maxillary midline diastema width (in mm) by governorate. 0.3 0.25 0.2 0.26 0.26 0.21 0.22 0.22 0.18 0.15 0.1 0.05 0 Aden Hadhrmot Hoddiedah Ibb Sana'a Taiz 4.4.1.5 Maxillary and mandibular anterior irregularity The results of the study show that irregularities were more common in the mandible, 43.2%, than in the maxilla, 37.3%, (Table 4-34). These differences were statistically significant. In the present study the size of the irregularities ranged from 1 to 6 mm in the maxilla and from 1 to 5 mm in the mandible. Irregularities 1 mm to 3 mm were more prevalent in the mandible. Irregularities of 4 mm however were more prevalent in the maxilla. 104 Chapter three Results Table 4-34: The prevalence of maxillary and mandibular anterior irregularity. Anterior irregularity Maxilla Mandible No irregularity 62.7 56.8 Largest irregularity 37.3 43.2 P<0.05 1 mm 17.3 24.0 2 mm 13.0 12.0 3 mm 2.9 4.8 4 mm 2.9 1.3 5 mm 0.7 1.3 6 mm 0.5 0.0 4.4.1.5.1 Maxillary irregularity Maxillary anterior irregularities were found in 37.3% of the sample. The largest maxillary anterior irregularity was mostly of 1mm 17.3 % and 13.0 % was 2mm, while only 7.0% of the sample showed irregularities of 3mm or more as shown in (Table 4-34). Considering residency differences, urban children had more maxillary anterior irregularities (both in prevalence and mean) than rural children, and this was statistically significant as shown in (Table 4-35). 105 Chapter three Results Table 4-35: Percentage and frequency distribution largest maxillary anterior irregularity by residency. Largest maxillary irregularity Urban Rural Frequency % Frequency % No irregularity present 924 61.5 958 63.8 Irregularity present 578 38.5 543 36.2 P<0.05 Table 4-36 summarises the prevalence of largest maxillary irregularity by dentition stage. Maxillary anterior irregularities more prevalent in early permanent dentition stage 38.6 % than in late mixed dentition stage 33.6 %. Table 4-36: Percentage and frequency distribution of largest maxillary anterior irregularity by dentition stage. largest maxillary irregularity Late mixed Early permanent dentition dentition Frequency % Frequency % No irregularity present 521 66.4 1361 61.4 Irregularity present 264 33.6 857 38.6 P<0.05 106 Chapter three Results 4.4.1.5.2 Mandibular anterior irregularity Mandibular anterior irregularities were found in 43.2% of the sample. The largest mandibular anterior irregularity was mostly of 1 mm 24.0 % and 12% was 2 mm, while only 7.2% of the sample showed irregularities of 3 mm or more as shown in (Table 4-34). The results of the study showed that urban children had statistically significant more mandibular anterior irregularities than rural children as shown in (Table 4-37). Table 4-37: Percentage and frequency distribution largest mandibular anterior irregularity by residency. Largest mandibular irregularity Urban Frequency Rural % Frequency % No irregularity present 827 55.1 878 58.5 Irregularity present 675 44.9 623 41.5 P<0.05 107 Chapter three Results 4.4.2 DISCREPANCIES IN OCCLUSAL CONTACT RELATIONSHIP 4.4.2.1 Anterior maxillary overjet The percentage of children that presented with a maxillary overjet is shown in (Figure 4-8). The results of the study indicated that 55.0% of the subjects presented with a normal maxillary overjet ranged from 1 to 3 mm, 11.5% presented with a 0 mm overjet (edge-to-edge) and 32.5% presented with an overjet larger than 3mm. The increased overjet ranged from 4 mm to 9 mm. An overjet of 4 mm to 6 mm occurred in 31.5% of the children, and an overjet of more than 6mm occurred in only 2.0% of the children. Figure 4-8: Distribution of maxillary overjet for the total sample >6 m m 2.0% 0 mm 11.5% >3-6 m m 31.5% 0 mm 1-3 m m 55.0% 1-3 mm >3-6 mm 108 >6 mm Chapter three Results The percentage distribution of maxillary overjet for males and females is presented in (Table 4-38) and (Figure 4-9). The interaction between maxillary overjet and gender showed statistical significance, indicating that the distribution of maxillary overjet is statistically significant different for the gender groups. Table 4-38: The percentage distribution of maxillary overjet by gender. Gender 0 mm 1-3 mm > 3 mm Male 10.9 52.7 36.5 Female 12.1 57.2 30.7 P<0.05 109 Chapter three Results Figure 4-9: Distribution of the total sample according to their overjet values by gender. % 40 35 Males 30 Females 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Overjet value (mm) The results indicated that more boys than girls had an increased overjet, i.e. overjet more than 3 mm and more girls than boys had an edge-to-edge overjet (0 mm overjet). The interaction between maxillary overjet and gender was further investigated by considering independent samples T-test and the associated p values (Table 4-39). 110 Chapter three Results Table 4-39: The interaction between maxillary overjet and gender. Gender Mean Female 2.80 Male 2.94 Std. error Std. Deviation .040 t P value -2.349 0.017 1.560 .042 1.612 The percentage distribution of maxillary overjet for the two dentition stages is presented in (Table 4-40). The distribution between these stages of dental development showed statistically significant difference (p<0.05). Table 4-40: The percentage distribution of maxillary overjet for the late mixed dentition stage and the early permanent dentition stage. Dentition stage 0 mm 1-3 mm > 3mm Late mixed dentition 13.6 50.6 35.7 Early permanent dentition 10.7 56.5 32.8 P<0.05 111 Chapter three Results The percentage distribution of maxillary overjet according to governorate is presented in (Table 4-41). The distribution of maxillary overjet differs significantly for the different governorate (p<0.05). Table 4-41: The percentage distribution of maxillary overjet by governorate. Governorate 0 mm 1-3 mm > 3 mm Aden 17.6 52.0 30.4 Hadhramot 15.0 46.8 28.2 Hoddiedah 8.2 55.0 36.8 Ibb 13.8 52.4 33.4 Sana'a 7.6 56.5 36.0 Taiz 6.8 57.0 36.2 P<0.05 The mean maxillary overjet of the sample was 2.9 mm. The highest mean overjet was in Taiz 3.14 mm and least in Aden 2.54 mm as shown in (Figure 4-10). The differences between the six governorates for mean overjet was statistically significant by ANOVA test (F=17.259, df =5, 2997, p<0.05). 112 Chapter three Results Figure 4-10: Mean maxillary overjet (in mm) by governorate. 3.5 3.14 3 2.54 3.13 3.14 2.72 2.58 2.5 2 1.5 1 0.5 0 Aden Hadhrmot Hoddiedah 113 Ibb Sana'a Taiz Chapter three Results 4.4.2.2 Anterior mandibular overjet Anterior mandibular overjet much less frequent with an occurrence of only 10.7% in the sample (Figure 4-11). Figure 4-11: distribution of anterior mandibular overjet for the total sample. = >4 very great treatment need 0.73 Absent 89.31 1 - 3mm great treatment need 9.95 The gender distribution of anterior mandibular overjet is shown in (Table 4-42). There was no significant difference in the distribution of anterior mandibular overjet between males and females in this age group in Yemen. 114 Chapter three Results Table 4-42: Gender distribution of anterior mandibular overjet in 12-year-old Yemeni school children. Gender Percentage distribution (%) Males 10.1 Females 11.3 p>0.05 Considering residency, statistically insignificant difference was found in the prevalence of anterior mandibular overjet between rural females and males (x2=6.627, df =4, P>0.05). Also an insignificant difference was found in the prevalence of anterior mandibular overjet between urban females and males (x2=1.458, df =4, P>0.05) as shown in (Table 4-43). Table 4-43: Distribution of anterior mandibular overjet by residency and gender. Residency Rural Urban Gender 0 mm 1-3 mm =>4 mm Female 87.5 11.5 1.1 Male 90.5 9.2 0.3 Female 90.0 9.1 0.9 Male 89.2 10.1 0.7 115 Chapter three Results The distribution of anterior mandibular overjet in the late mixed and early permanent dentition is shown in (Table 4-44). The distribution of mandibular overjet between the late mixed dentition stage and the early permanent dentition stage was statistically significant different. Table 4-44: The percentage distribution of mandibular overjet by dentition stage. Dentition stage Percentage distribution (%) Late mixed dentition 13.3 Early permanent dentition 8.9 P<0.05 4.4.2.3 Vertical anterior openbite In the present study 8.3% of the children examined presented with an anterior openbite, the size of which ranged from 1 to 5mm (Table 4-45). Table 4-45: Percentage and frequency distribution of vertical anterior openbite for the total sample. Vertical anterior openbite Frequency Percentage distribution (%) Absent Present 2755 248 91.7 8.3 1 mm 2 mm 3 mm 4 mm 5 mm 104 74 36 16 8 3.5 2.5 1.4 0.6 0.3 116 Chapter three Results The results of the study showed that a moderate anterior openbite occurred in 6% of the sample, a severe openbite in 2% and an extreme openbite occurred in 0.3 % (Table 4-46). Table 4-46: The percentage distribution of vertical anterior openbite of the affected group. Vertical anterior openbite Percentage distribution (%) Moderate: 1 to 2mm 6.0 Severe: 3 to 4mm 2.0 Extreme: > 4mm 0.3 The gender distribution of anterior openbite is shown in (Table 4-47). There is no statistically significant difference in the distribution of anterior openbite between males and females in this age group in Yemen. Table 4-47: Gender distribution of vertical anterior openbite in 12year-old Yemeni school children. Gender Percentage distribution (%) Males 7.3 Females 9.2 P>0.05 117 Chapter three Results Differences between males and females regarding the mean vertical anterior openbite were further investigated by independent samples T-test. The results of the present study indicated that females had a higher mean of vertical anterior openbite 0.19 mm than males 0.14 mm. These differences were statistically significant as shown in (Figure 4-12). Figure 4-12: Mean vertical anterior openbite by gender. Males 0.14 Females 0.19 0 0.05 0.1 mm 118 0.15 0.2 Chapter three Results The percentage distribution of vertical anterior openbite in the late mixed dentition stage and the early permanent dentition stage is shown in (Table 4-48). Anterior openbite is more prevalent in the late mixed dentition stage 11.1% than in the early permanent dentition stage 7.3%. The differences between the two groups were statistically significant (p<0.05). Table 4-48: The percentage distribution of vertical anterior openbite according to dentition stage. Dentition stage Percentage distribution (%) Late mixed dentition 11.1 Early permanent dentition 7.3 P<0.05 The percentage distribution of vertical anterior openbite according to different governorate of Yemen is presented in (Table 4-49). The distribution of vertical anterior openbite showed statistically significant difference for the different governorates (p<0.05). 119 Chapter three Results Table 4-49: The percentage distribution of vertical anterior openbite by governorate. Governorate Openbite Aden Hadhramot Hoddiedah Ibb Sana'a Taiz Moderate: 0 to 2mm Severe: 3 to 4mm Extreme: > 4mm 8.8 2.8 0.6 7.4 1.6 0.0 5.8 1.8 0.8 5.6 2.6 0.4 4.6 2.0 0.4 3.4 1.0 0.0 Total 12.2 9.0 8.4 8.6 7.0 4.4 P<0.05 Because the interaction between vertical anterior openbite according to governorate was statistically significant (p<0.05), the nature of the interaction was investigated by ANOVA test and the associated p-values. The results for the interaction of vertical anterior openbite and different governorates summarised in (Table 4-50). Table 4-50: The interaction between vertical anterior openbite according to governorate by AVOVA test. Governorate n Mean Std. Deviation Std. error Aden Hadhramot Hoddiedah Ibb Sana'a Taiz Total 500 500 500 500 503 500 3003 0.24 0.15 0.18 0.18 0.16 0.09 0.17 0.763 0.534 0.689 0.681 0.648 0.446 0.637 0.034 0.024 0.031 0.030 0.029 0.020 0.029 df F P 5, 2997 3.325 0.005 120 is Chapter three Results 4.4.2.4 Antero-posterior molar relation The prevalence of discrepancies in the antero-posterior molar relationship is presented in (Table 4-51). The results indicated that 69.43% of the sample presented with a normal molar relationship and 30.56% presented with an antero-posterior molar relationship discrepancy. Of the affected group 19.78% presented with a half a cusp displacement and 10.78% presented with a full cusp displacement. Table 4-51: Prevalence of the antero-posterior molar relationship. Antero-posterior molar relationship Frequency % Normal relationship 2085 69.43 Abnormal relationship 918 30.56 Half a cusp displacement 594 19.78 Full cusp displacement 324 10.78 The percentage distribution of antero-posterior molar relation for males and females are presented in (Table 4-52). The differences in the distribution of antero-posterior molar relation for male and females was statistically significant (p<0.05). 121 Chapter three Results Table 4-52: The percentage distribution of antero-posterior molar relation for males and females. Gender Normal Half a cusp displacement Full cusp displacement Male 67.3 22.2 10.5 Female 71.6 17.4 11.1 P<0.05 The interaction between gender group and antero-posterior molar relation was statistically significant (p<0.05), i.e. there are significantly more girls than boys with a normal molar relationship. The distribution of antero-posterior molar relation according to residency was statistically insignificant. Half cusp displacement was found more prevalent in rural children, while full cusp displacement was found more prevalent in urban children as shown in (Table 4-53). Table 4-53: The percentage distribution of antero-posterior molar relation by residency Residency normal Half cusp displacement Full cusp displacement rural 69.0 21.2 9.8 urban 69.8 18.4 11.8 Total 69.4 19.8 10.8 P>0.05 122 Chapter three The Results percentage distribution of antero-posterior molar relation for the late mixed dentition stage and the early permanent dentition stage is presented in (Table 4-54). The differences in the distribution of antero-posterior molar relation for the late mixed dentition stage and the early permanent dentition stage was not statistically significant for the total sample (p>0.05). Table 4-54: The percentage distribution of antero-posterior molar relation by dentition stage. Dentition stage Late mixed dentition Early permanent dentition Half a cusp Full cusp displacement displacement 71.2 18.5 10.3 68.8 20.2 11.0 Normal P>0.05 4.5 PREVALENCE AND TREATMENT NEED OF MALOCCLUSION IN Yemen The distribution of the scores of the dental aesthetic index (DAI) for the total sample is displayed in (Table 4-55 and Figure 413). The highest DAI score registered was 46 and the most commonly registered DAI score was 23 about 9.8%. 123 Chapter three Results Table 4-55: Distribution of total sample according to their DAI scores. grade score DAI DAI % grade score % 13 12 .4 0.4 14 10 .3 0.7 15 43 1.4 2.2 16 72 2.4 4.6 17 86 2.9 7.4 18 39 1.3 n % Cumulative % 31 138 4.6 85.9 32 113 3.8 89.7 33 57 1.9 91.6 34 44 1.5 93.0 35 32 1.1 94.1 8.7 36 29 1.0 95.1 19 241 8.0 16.7 37 22 0.7 95.8 20 205 6.8 23.6 38 23 0.8 96.6 21 241 8.0 31.6 39 25 0.8 97.4 22 278 9.3 40.9 40 24 0.8 98.2 23 293 9.8 50.6 41 15 0.5 98.7 24 201 6.7 57.3 42 4 0.1 98.8 25 184 6.1 63.4 43 5 0.2 99.0 26 108 3.6 67.0 44 11 0.4 99.4 27 134 4.5 71.5 45 8 0.3 99.6 46 11 0.4 100.0 28 29 30 99 3.3 74.8 112 3.7 78.5 84 2.8 Very sever (handicapping)malocclusion Definite malocclusion Cumulative n Sever malocclusion DAI Normal or minor malocclusion DAI 81.3 124 Chapter three Results Figure 4-13: Distribution of total sample according to their DAI scores. %10 9 8 7 6 5 4 3 2 1 0 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 DAI score The prevalence and severity of malocclusion and the recommended orthodontic treatment need for each of the categories of the DAI is summarised in (Table 4-56). The results show that 63.4% of children in the sample presented with either good occlusion or minor malocclusion. Just over 36.6% presented with identifiable malocclusion, i.e. a DAI score larger than 26. Of these 17.7% had definite malocclusion, 13.0% had severe malocclusion and 6.0% had very severe or handicapping malocclusion. Almost sixty-four per cent of the children examined had a dental appearance where orthodontic treatment need is ‘slight’ or ‘not indicated’. Just over eighteen per cent of the 12-year-old children fell into the malocclusion group where orthodontic treatment is considered ‘elective’. The rest of the sample presented with malocclusion varying from severe to very severe 125 Chapter three Results where orthodontic treatment is ‘highly desirable’ 13.0% and ‘mandatory’ 6.0%. Table 4-56: Orthodontic treatment need of 12-year-old Yemeni children according to the DAI. DAI score ≤ 25 26 – 30 31 – 35 ≥ 36 Severity levels Normal or minor malocclusion No treatment need or slight need Definite malocclusion Treatment elective Severe malocclusion Treatment highly desirable Very severe (handicapping) malocclusion Treatment mandatory Frequency % 1901 63.4 532 17.7 391 13.0 179 6.0 4.6 PREVALENCE OF MALOCCLUSION BY GOVERNORATE The frequency and percentage distribution of the DAI categories in the six examined governorates is summarised in (Table 4-57). DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found in Ibb 24.0%, followed by Sana'a 23.3%. 126 Chapter three Results Table 4-57: The frequency and percentage distribution of the DAI groups for the sample by governorate. Governorate Aden Hadhramot Hoddiedah Ibb Sana'a Taiz Total Frequency % Frequency % Frequency % Frequency % Frequency % Frequency % Frequency % 13-25 26-30 31-35 >36 352 70.4 343 68.6 313 62.6 266 53.2 322 64.0 305 61.0 1901 63.3 56 11.2 91 18.2 80 16.0 114 22.8 79 15.7 112 22.4 532 17.7 60 12.0 52 10.4 67 13.4 83 16.6 67 13.3 62 12.4 391 13.0 32 6.4 14 2.8 40 8.0 37 7.4 35 7.0 21 4.2 179 6.0 Mean Std. error 24.25 0.282 23.81 0.238 25.40 0.275 25.60 0.286 25.17 0.272 24.91 0.242 24.86 0.109 Considering the mean DAI scores, Ibb showed the highest mean 25.60 followed by Hoddiedah 25.40 as shown in (Table 4-57 and Figure 4-14). These differences were found to be statistically significant as shown by ANOVA test (F=6.795, df =5, 2997, p<0.05). 127 Chapter three Results Figure 4-14: Mean DAI scores by governorate. 26 25.6 25.4 25.5 25.17 24.91 25 24.5 24.25 24 23.81 23.5 23 22.5 Aden Hadhrmot Hoddiedah Ibb Sana'a Taiz 4.7 PREVALENCE OF MALOCCLUSION BY GENDER The frequency and percentage distribution of the DAI categories for the different gender groups is shown in (Table 458). DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found more prevalent in females 21.5% than males 16.5%, while DAI scores of 13 to 25 where there is no treatment need or slight need were found more prevalent in males 65.3% than females 60.9%. 128 Chapter three Results Males showed comparable mean DAI scores 24.67 to that of females 25.05 as shown in (Table 4-58). This result was statistically insignificant (t=-1.745, df =3001, p>0.05). Table 4-58: The frequency and percentage distribution of the DAI groups by gender. 13 - 25 26 - 30 31- 35 Male ≥36 Frequency 991 266 169 78 % 65.3 17.5 11.3 5.2 912 266 222 101 60.9 17.7 14.8 6.7 Female Frequency % Mean Std. error 24.67 0.163 25.05 0.145 4.8 PREVALENCE OF MALOCCLUSION BY RESIDENCY The prevalence of malocclusion by residency is presented in (Table 4-59). No difference was observed in the prevalence of malocclusion in the different location types i.e. urban and nonurban schools and means of DAI scores 129 Chapter three Results Table 4-59: The frequency and percentage distribution of the DAI groups by residency. 13-25 Residency 26-30 31-35 ≥ 36 Mean Rural school Frequency 969 264 188 80 % 64.6 17.6 12.5 5.3 Urban school Frequency 932 268 203 99 % 62.1 17.8 13.5 6.6 Frequency 1901 532 391 179 % 63.3 17.7 13.0 6.0 Total 24.64 25.07 Std. error 0.154 0.155 DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found more prevalent in rural females 23.2% than rural males 13.5%. These differences were found to be statistically significant, while statistically insignificant differences were found between urban males and females as shown in (Figure 4-15). 130 Chapter three Results Figure 4-15: Distribution of DAI scores by gender and residency. 36-46 31-35 26-30 Urban males 61 Urban females 63 70.6 Rural males 58.5 Rural females 0% 13-25 20% 40% 60% 80% 100% 4.9 PREVALENCE OF MALOCCLUSION ACCORDING TO EMPLOYMENT STATUS OF PARENTS The percentage and frequency distribution of malocclusion according to employment status of the parents are presented in (Tables 4-60). The prevalence of malocclusion by employment status of the parent was not statistically significant different (p>0.05). 131 Chapter three Results DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found more prevalent in children with unemployed parents 19.6% than children with employed parents 18.4%, these differences were found to be statistically significant (p>0.05). Table 4-60: The percentage and frequency distribution of the DAI groups according to employment status of parents. Employed Unemployed Total 13-25 26-30 31-35 ≥ 36 Frequency 1599 449 331 129 % 63.7 17.9 13.2 5.2 Frequency 310 86 63 34 % 62.9 17.5 12.8 6.8 Frequency 1909 535 394 163 % 63.6 17.8 13.1 5.4 P>0.05 132 Chapter four Discussion Discussion Study and determination of criterion for different ethnic groups is essential to promote accurate diagnosis and planning for orthodontic treatment. Each ethnic group has certain characteristics that should not be taken as standards for other areas with different developmental and ecological foundation. In Yemen there was no previous study, so we can not make comparisons. However, this study will be the first data on the orthodontic status and orthodontic treatment need, which will form a database which is one of the aims of the present investigation. This study included three main parts:1. A questionnaire to assess the perception of the children self malocclusion. 2. Intra-oral examination to assess the orthodontic status of the children. 3. Assessment of the need of orthodontic treatment need according to the Dental Aesthetic Index. Compared with other investigations in other countries, the present subjects represent a different population in terms of geographic, social and cultural points of view. Also comparisons with other studies is not always possible because the differences in definitions of the examined occlusal features, varying examination techniques and different indices. Thus, comparison will be made with those studies carried out on a similar age group using a similar methodology emphasizing on those performed on samples from Arabic countries. 132 Chapter four Discussion 5.1 SAMPLE SELECTION: The study population was relatively evenly distributed on the basis of gender and residency (urban or rural) and governorate. The study was to be performed on 12-year-old children. Most 12-year-old children will present with a dentition in the early permanent dentition stage, and the remainder will still be in the late mixed dentition stage (2). The multi-stage stratified sampling technique in this investigation was similar to that used by previous national oral health studies. This sophisticated method was carried out to make the sample representative of the target population. 5.2 METHOD: The intra-oral examination of occlusal features was divided into two main parts similar to Drummond (239) : a. Intra-arch irregularities and malalignment b. Discrepancies in occlusal contact relationship Listed in the review of literature chapter several indices of treatment need, of whom the Dental Aesthetic Index was chosen in this research because: 1. It is simple. 2. It is reliable (78, 240). 3. It is valid (78, 196, 240,241). 4. It is relatively fast (about 2-3 minutes for each child) (242) . 5. It accounts for both (function and aesthetics). 6. It was adopted by the WHO making it a universally acceptable index. 133 Chapter four Discussion 7. The dental aesthetic index has decision points differentiating treatment priority. 5.3 QUESTIONNAIRE: Before discussing the four questions regarding the awareness of malocclusion we will discuss the three questions regarding the past and present orthodontic treatment of the children. Of the sample, 0.9% did or were doing orthodontic treatment, 1.3% had undergone extractions to improve appearance, and 0.5% reported that their treatment was postponed by a dentist for a later time; giving a total of 2.7% of the sample who have had some type of orthodontic treatment or consultation. The percentage is very small when compared to studies carried out in European countries as Sweden, Denmark and Finland which show that about 27-45% of their samples have received some sort of orthodontic treatment in (Table 5-1). 134 (243-247) as it is shown Chapter four Discussion Table 5-1: Reported prevalences of received orthodontic treatment Sample Author Ast et al. (184) Ng’ang’ et al. (185) Ingervall & Hedegârd (186) Treatment received Country Size Age % Comments America 1413 15-18 9.6 Kenya 919 13-15 4 Sweden 278 18 16 Appliances 158 20-29 28 Treated 190 30-39 8 Treated 111 35 34.2 100 18 40 Extractions or appliances Treated Salonen et al. (194) Sweden Espeland et al. (195) Norway Tuominen et al. (197) Finland 340 16-19 37.7 Treated Tuominen et al. (203) Finland 226 13-15 38.5 Treated (212) Sweden 272 20-45 25 Treated adult women Helm et al. (223) Denmark 997 28-34 30 Treated with request for Helm (243) Denmark 1700 9-18 26 Treated/ extractions Helm et al. (244) Denmark 293 13-17 Sweden 925 14 25-37 Finland 280 15-16 42 Spencer et al. (248) Australia 2793 13-15 15.5 Bergström & Halling (249) Sweden 942 19 28 Mohlin Bernhold & Lindqvist Pietilä & Pietilä (245) (247) 135 1 Low treatment uptake area Normal treatment uptake area appliances 19 Treated/ extractions 14 appliances Treated in various areas Treated Fixed appliance treatment Treated in various areas Chapter four Discussion On the other hand Al-Huwaizi (225) found that 3.2% of his sample had some type of orthodontic treatment or consultation, and this figure was close to ours. The scarcity of orthodontic treatment may be explained by the small number of dentist in general and orthodontic specialists in specific in Yemen and the lack of a health insurance system concerned with orthodontic treatment in Yemen. The children who did or were doing orthodontic treatment were mostly from Sana'a, Aden and Taiz and least in Hadhrmot and Ibb, while those who had undergone extractions to improve appearance were mostly from Taiz, Sana'a and Aden. This may be because the majority of the orthodontic specialists reside in Sana'a while, Ibb and Hadhrmot at the time of research had no orthodontist making general practitioners favour extractions to improve appearance rather than to refer the patients to Sana'a. Females showed more orthodontic treatment (appliances or extraction) than males in accordance with Al-Huwaizi (225) which may be because females are more concerned with their appearance than males. Orthodontic treatment (appliances or extraction) was found to be more in the urban sample than in the rural sample. This could be explained by the fact that all orthodontic specialists in Yemen reside and practice in the large cities making it more difficult for the rural children to obtain treatment. 136 Chapter four Discussion 5.3.1 Question 1 (Teeth alignment) Regarding the self-evaluation of the children to the alignment of their teeth, 29.7% of them answered that they have malaligned teeth. This was similar to that found by Salonen et al. (194) but less than that of Ng'ang'a et al. (202) as presented in (Table 2-12). (199) and Ingervall et al. The awareness of malocclusion was significantly more in Sana'a and Aden and least in Hadhrmot and Hoddiedah, and significantly more in urban children than rural children. These results are self-explanatory since people living in the capital and large cities are more exposed to the media and public dental health education programs than those living in smaller cities, towns or villages together with the presence of children undergoing orthodontic treatment increases the awareness of the other children to their occlusion. The awareness of malocclusion was significantly more in females than males, which is similar to the finding of Salonen et al. (194) this again may be because females are more concerned with their appearance than males. However, Ng'ang'a et al. (199) found no significant difference which may be attributed to cultural and/or social differences. 137 Chapter four Discussion 5.3.2 Question 2 (Type of malalignment): Concerning the type of malaligned teeth, the children reported their malocclusion type as follows in descending sequence of prevalence crowded, protruded, rotated and displaced teeth, and spaced teeth. This sequence is different from that of Abdulla (204) and others as shown in table 2-14, but is identical to the findings of Graber and Lucker (224) and Al- Huwaizi (225) . A significant difference was found between the governorates in which crowded teeth were mostly found in Taiz, spaced teeth were mostly found in Ibb, protruded teeth were mostly found in Hoddiedah and rotated and displaced teeth in Aden. This may be explained by the fact that a variety of social and cultural factors may influence perception of physical attractiveness (15). 5.3.3 Question 3 (Effect of malalignment): Of the 892 children who stated that they have malaligned teeth, 61.3% thought that it affected their appearance, 6.8% affected chewing and 7.7% affected speech, while 24.9% answered that malaligned teeth did not affected appearance, chewing or speech. This result is comparable to that found by Batayine (14) in Jordan and Al- Huwaizi (225) in Iraq. Appearance was the highest concern of children in Sana'a and Aden and least in Hoddiedah and Hadhrmot. However, those who reported that their malocclusion has no effect have a reverse distribution in which Hadhrmot showed the highest percentage, followed by Hoddiedah and Taiz, and was lowest in Sana'a and Aden. This reflects the same picture as the previous findings that 138 Chapter four Discussion people living in the capital and large cities are more concerned with their appearance than those living in smaller cities, towns or villages. The previous statement also applies for the finding of this investigation that the urban sample answered significantly more to ‘affected appearance’ and less to ‘no effect’ than the rural sample. 5.3.4 Question 4 (Seeking treatment): The most common reason for not seeking orthodontic treatment was that the children didn't know, treatment is not important, treatment is not possible, fear of pain and fear of tooth extraction. The predominance of fear of pain is similar to that of Batayine (14) , Al- Huwaizi (225) and Gatchel (250) . About two thirds of the sample didn't know or believed in the impossibility of treatment or its unimportance. This is a communal problem and can be solved by education of the community through the media or public dental health education programs. 5.4.1 COMPOSITION OF THE SAMPLE IN TERMS OF DENTITION STAGE Proffit suggested that the morphological variation with age may not be related to chronological age but to the stage of dental development. Most 12-year-old children will present with a dentition in the early permanent dentition stage, and the remainder will still be in the late mixed dentition stage (2, 238). 139 Chapter four Discussion Division of the sample in the late mixed dentition stage and early dentition stage indicated that 26.1% of the study population were still in the late mixed dentition stage and 73.9% presented with a dentition in the early permanent stage. These findings may be important in the interpretation of the results of the study. The DAI was developed to assess the prevalence of malocclusion in the permanent dentition stage (159) . Some of the occlusal traits measured will improve with the transition from the mixed dentition stage to the permanent dentition stage, resulting in an improvement of the DAI score (172, 178, 251, 252). 5.4.2 THE PREVALENCE OF DENTITION STAGE BY GENDER The results indicated that a considerable number of 12-yearold girls presented with a dentition in the early permanent stage than boys, 77.61 % and 70.11 % respectively. The distribution of the number of males and females in the two stages of dental development was significantly different (p<0.05). This is in accordance with the finding of Johnson and Harkness (174) and Drummond (239) , although the former studied the prevalence of malocclusion and orthodontic treatment need in 10year-old New Zealand children using the DAI and found statistically significant gender differences in the study sample, while Drummond investigated a group of South African children. These variations may be attributed to the differences in dental development and the early maturation of girls. 140 Chapter four Discussion 5.5 ORTHODONTIC STATUS According to Proffit et al. (107) two major types of malocclusion occur, intra-arch irregularities and malalignment, and discrepancies in occlusal contact relationship. The Dental Aesthetic Index (78) makes provision for the analysis of data into these two categories as well as the individual variables. 5.5.1 INTRA-ARCH IRREGULARITIES AND MALALIGNMENT 5.5.1. 1 Missing maxillary and mandibular incisors, canines and premolars: In the present study, 7.9% of the sample were found to have one or more missing visible tooth (incisors, canines and premolars); of whom 6.2 % had one missing visible tooth, 1.5% had two missing teeth and 0.3% had three missing visible teeth. This was much higher than 6% of Batayine Al-Huwaizi (14) and (225) 3.4 % of . However, it was lower than 10% of Abdulla and 9.7% of Drummond (239) (204) as shown in (Table 5-2). The present study reveals a significant difference in the prevalence of missing visible teeth between males and females with the higher prevalence being in females. However, Al-Huwaizi (225) reported no significant difference between males and females, but it is worthy mentioning that he reported that males showed a higher prevalence than females. The differences observed in (Table 5-2) between the prevalence of missing visible teeth of the present study and those reported by other studies are probably related to the high 141 Chapter four Discussion prevalence of caries in this Yemeni age group and week dental health services in addition to different sample size, age group and racial variation. Table 5-2: Reported prevalences of missing teeth. Sample Author Missing teeth (%) Country Size Age Jordan 200 13 94 Massler & Frankel (74) America 2758 14-18 Average 1.01 extracted tooth Cons et al. (78) America 1337 15-18 66.12 14.36 Ast et al. (184) America 1413 15-18 73.03 13 9.5 Abdulla (204) Iraq 200 13 90 7 2 Al-Huwaizi (225) Iraq 7120 13 96.6 Drummond (239) South Africa 5744 12 90.3 12-16 94 6 90.2 9.8 73.4 26.6 Batayie (14) Garner & Butt (253) Schaschula et al. (254) Al-Makadsi & AlSahar* (255) American Blacks Kenya Australian aborigines Iraq 427 15 0 1 2 3 10.25 3.81 5.45 1.91 2.55 0.5 3.4 Drummond 239 * Included extracted, congenitally missing and teeth indicated for extraction. 142 4 0.5 Chapter four Discussion 5.5.1.2 Crowding in the incisal segments: Crowding of the incisors is the most common form of Angle Class I malocclusion and is by far the most prevalent form of malocclusion (238). The results of the present study indicated that 31.5% of the children, presented with crowding in the incisal segments, 20.5% presented with crowding in one segment and 10.9% presented with crowding in two segments. The prevalence of crowding in this study was much higher than that of Al-Huwaizi (225) in his 13 year old Iraqi sample. The reason for this may be the difference in the criteria used as he recorded space discrepancies ≥2 mm. However, it was lower than that of Batayine (14) and Abdulla (204) in their Jordanian and Iraqi samples respectively and of Drummond (239) in his 12 year old South African sample as shown in (Table 5-3). The comparison with other studies on crowding (Table 5-3) is difficult because of the differences in the age of the sample, criteria and method used to assess the space discrepancy. As for gender differences, this study revealed non-significant differences between the two genders concerning the distribution of crowding. This coincides with the findings of Al-Huwaizi it contradicts that of Salonen et al. (194) (225) , while who found that females had more crowding than males, which may be attributed to sample size, age group and racial variation. However the present study reveals an insignificant difference in the prevalence of crowding between the late mixed dentition stage and the early permanent dentition stage. 143 Chapter four Farah Discussion (192) examined 9-10 year old Iraqi children and found less incisor crowding than in this study. This may be explained by the fact that at 9-10 years of age there is normal anterior spacing (ugly duckling stage) and by the age of 12-13 the canines erupt closing the anterior spaces which also increases anterior crowding and decreases posterior crowding. The slight increase in the anterior arch dimension during normal development is not sufficient to overcome moderate to severe discrepancies. Crowding is therefore likely to persist into the permanent dentition, particularly if it was severe initially.238 Proffit et al. reported that crowding of incisors affects nearly half of all children in the mixed dentition years; it worsens in the adolescent years as the permanent teeth erupt and continues to increase, especially in the mandibular arch, in adults (107). The prevalence of crowding differed significantly between the six examined governorates in which Taiz and Sana'a showed the highest prevalence, while Ibb and Hadhrmot showed the lowest prevalence. This difference may be attributed to the variation in some genetic and environmental factors in addition to different dietary habits and a further in depth is recommended. 144 Chapter four Discussion Table 5-3: Reported prevalences of crowding. Gardiner (10) Country Libya Sample Size 479 Batayie @ (14) Jordan 200 Author 13 17-26 (M) Poulton & Aaronson (63) Foster & Day (189) Age 10-12 England 1000 11-12 Iraq 101 9-10 Sweden 669 ≥20 Sweden 427 21-54 Iraq 200 13 Mohlin (212) Sweden 272 20-45 Gosney (215) Britain Farah * (192) Salonen et al. (194) Ingervall et al. * (202) Abdulla @ (204) 5-16 Al-Huwaizi * (225) Iraq 7120 13 Al-Alousi et al. (235) Iraq 952 16-24 South Africa 5744 12 Drummond (239) Lavelle & Foster (256) Britain 18-25 Cons et al.* (257) America 1337 15-18 Hill (258) Scotland 765 9-15 Office of Population Censuses and Surveys Britain Trottman & Elsbach (260) America (259) * space discrepancy ≥2 mm; 12 99 black 139 white @ 3-5 Crowding 30.7% 32.8% (Max. ant) 62.8% (Mand. ant) 22% ½ width of Mand. Incisor 4% width of one Incisor 30.6% (Max. ant) 30.4% (Mand. ant) 61.3% (Dentition) 6.9% (Max. ancisors) 8.9% (Mand. ancisors) 14.2% (M), 22.6% (F) 37% 37.5% (Max. ant) 67.7% (Mand. ant) 23% (Max.) 42.9% (Mand.) 71% (M), 69% (F) 9.7% (Max. ant) 19.4% (Mand. ant) 16.2% Crowded dentition 40% Max. 71% (M), 79% (F) Mand. 65.8% (M), 69.5% (F) 18.0% (Max. ant) 17.3% (Mand. ant) 27.8% (Max. ant) 48.6% (Mand. ant) 18% crowding sufficient to prevent eruption 16.2% (ant) 15.1% (ant) space discrepancy >0.5 mm 145 Chapter four Discussion 5.5.1.3 Spacing in the incisal segments The results of the present study indicated that 24.3% of the children examined , presented with spacing in the incisal segments, 17.9% presented with spacing in one segment and 6.4% presented with spacing in two segments. One of the characteristic features of normal occlusion is arch continuity as expressed by proximal contact between all teeth in each dental arch. Factors such as mesial drift, transeptal fibres, the slope of the occluding cusp and the direction of occlusal forces contribute to the maintenance of this continuity (261-263). The loss of contact as through loss of proximal tooth material is viewed as detrimental to arch integrity and normal function (264) . Hemley, on the other hand, claimed that spacing is an acceptable variation in the normal occlusion pattern and not a malocclusion (265). A considerable number of individuals show spaces between some, or even all, of their teeth. These are known as “spaced dentition” (264) . Spacing in the incisal segment is indicative of space excess in these segments. Spacing can be a symptom of missing or undersized lateral incisors, para-function habits such as thumb sucking, mouth-breathing and tongue-thrusting, flared or rotated central incisors, anodontia, macroglossia, dento-alveolar disproportions and true tooth size/jaw size discrepancies (266). 146 Chapter four Discussion The prevalence of spacing in the present study was much higher than that of Al-Huwaizi (225) in his 13 year old Iraqi sample. The reason for this is the difference in the criteria used as he recorded space discrepancies ≥2 mm. However, it was lower than (264) that of Steigman & Weissberg Palestinian sample and of Drummond in their 12-14 year old (239) in his 12- year-old South African sample as shown in (Table 5-4). Comparisons with other studies on spacing (Table 4-5) is difficult because of the differences in the age of the samples, criteria and method used to assess the space discrepancy. Concerning gender differences, this study revealed nonsignificant differences between the two genders concerning the distribution Al-Huwaizi of spacing. This agrees with (225) the finding , while it contradicts with that of Abdulla (204) of who found that females had more spacing than males. In general, there were statistically insignificant differences between the six examined governorates for the distribution of spicing. Since, there is no previous local study so direct comparison was not possible. 147 Chapter four Discussion Table 5-4: Reported prevalences of spacing. South Drummond (239) Author Helm * (243) Gardiner (10) Sample 5744 12 27.65% Spacing Africa Country Size Age 9- Denmark 1700 Libya 479 1018 10.8% (M), 6.4% (F) 20.3% 12 Max. Lavelle & Foster (256) Batayie @ (14) Cons al. * Farah et * (192) (257) Salonen Hill (258) et al. (194) Steigman & Ingervall et al. * Weissberg # (264) 202 Abdulla Britain Jordan 200 America Iraq 1337 101 Scotland Sweden 765 669 Palestine Sweden 407 427 1813 25 30.7% ant)(F) 26.8% (Max. (M), 20% Mand. 14.3% (Mand. ant) 32.9% (M), 28.6% (F) 159- 10.5% (Max. ant) 12.9% (Max. ancisors) 18 10 2.7% (Mand. ant) 4.0% (Mand. ancisors) 9≥20 15 122114 54 8.5% (Max. ant) 12.7% (M), 7.7% (F) 53.1% 13% 32.5% (Max. ant) @ (204) Iraq 200 13 16.2% (Mand. ant) Mohlin (212) Sweden 20- 7% (Max.) 45 5% (Mand.) 272 5- Gosney (215) Britain 67% (M), 42% (F) 16 Al-Huwaizi * 9.9% (Max. ant) (225) Iraq 7120 13 3.5% (Mand. ant) * space discrepancy ≥2 mm; @ space discrepancy >0.5 mm ;# space discrepancy ≥0.2mm 148 Chapter four Discussion 5.5.1.4 Maxillary midline diastema A maxillary central diastema of 1mm or more was found in 14.2% of the sample and diastema of 2mm or more was found in 1.8 %. This was comparable to the 15% found by Abdulla (204) but much higher than that the 10.1% of Al-Huwaizi (225) in Iraq. This present Yemeni figure is close to that of other Arab population sample results (14, 204) and African population results (239) , but higher than that of Swedish population results (202, 212) and this may be attributed to racial differences (Table 5-5) Considering the total spacing, gender differences were statically insignificant which in agreement with the results achieved by Al-Huwaizi (225) and Al-Naddawi and Shareef (267) . If diastema larger than 2 mm is taken into account, the results show that about twice as many females than males presented with diastema. The differences between the two groups were statistically significant. The results indicate that there are more girls than boys with a midline diastema larger than 2 mm. These coincide with the findings of Drummond hand, Brunelle et al. (268) (239) . On the other found that males had significantly more diastemas than females. Midline diastema is more prevalent in the late mixed dentition than in the early permanent dentition. This was also true for a midline diastema larger than 2 mm. The result of the present study supports the findings by Richardson et al. (270) (269) and Lindsey who indicated that midline diastema reduces with the transition from the mixed dentition to the permanent dentition. 149 Chapter four Discussion In the developing dentition at the age of 12 years, the presence of a diastema is regarded as a normal phenomenon. In the absence of a deep overbite these spaces normally close spontaneously. If the space between the maxillary central incisors is greater than 2mm, spontaneous closure is unlikely (2, 238, 271). Taiz and Hoddiedah showed more diastema than other governorates. This also strengthens the previous theory of genetic and environmental differences. 150 Chapter four Discussion Table 5-5: Reported prevalences of maxillary central diastema. Al-Naddawi & (267) Al-Shareef Author Iraq Sample Country American Whites 18 553 Siz -60 Ag e e Brunelle et al. (268) Gardiner (10) American Blacks Libya Mexican Americans 479 Jordan 200 19.9 Diastema 6.9 ≥1mm ≥2mm Definition % 5.5 12 10 -17 -12 12.5 1 4.1 13 11.5 ≥2mm Any Not Batayie (14) mentioned Cons et al. (78) 133 15 16.5% ≥ 1mm 7 -18 5.3% ≥2mm 2 ≥2mm America Ingervall et al. 21 Sweden (202) 427 -54 Not Abdulla 204 Iraq 200 13 15 mentioned 20 Mohlin (212) Sweden 272 2 ≥2mm 10.1 ≥1mm 2.5 ≥2mm 19.2 ≥0.2mm 16.66 ≥1mm 3.2 ≥2mm -45 Al-Huwaizi (225) 695 Iraq 13 7 Steigman & Weissberg Drummond 12 (241) (239) Palestine 407 -14 574 South Africa 12 4 151 Chapter four Discussion 5.5.1.4 Maxillary and mandibular anterior irregularity Maxillary anterior irregularities were found in 37.3% of the sample, while mandibular anterior irregularities were found in 43.2% of the sample. The results of the present study coincide with the findings of Brunelle et al. (268) who studied 12- to 17-year-old American children. They reported that mandibular incisors appeared to have more alignment irregularities than maxillary incisors, while it (225) contradicts with the findings of Al-Huwaizi Iraqi sample and Drummond (239) in his 13 year old on his 12-year-old South African sample who found that maxillary incisors appeared to have more alignment irregularities than mandibular incisors (Table 5-6). However, to the knowledge of the author there are no other studies in the literature other than those mentioned above that reported detailed information on the largest anterior irregularities to compare with except for Cons et al. (257) who reported the amount of irregularity per site and not the largest anterior irregularity that was reported in the present study. It is remarkable that Cons et al. (257) reported that 92% of their sample had no irregularities recorded, but this may be because they included only irregularities of 2mm or more as suggested by Baume et al. (66) . Using the same criteria, in the present study, 93% had no maxillary anterior irregularities and 92% had no mandibular anterior irregularities. 152 Chapter four Discussion The results of the present study showed that maxillary irregularities were more prevalent in the early permanent dentition stage 38.6 % than in the late mixed dentition stage 33.6 %. This finding supports the previous mentioned finding that the slight increase in the anterior arch dimension during normal development is not sufficient to overcome moderate to severe discrepancies. Crowding and anterior irregularities is therefore likely to persist into the permanent dentition. Considering residency differences, this study revealed statistically significant difference between the two location areas, where urban children had more maxillary and mandibular anterior irregularities than rural children. This pattern is in agreement with that found by Al-Huwaizi Al-Huwaizi (225) (225) , but it is worth mentioning that reported higher maxillary and mandibular anterior irregularities in rural children than in urban children. Table 5-6: Reported prevalences of maxillary and mandibular anterior irregularities. Sample Author Al-Huwaizi (225 Anterior irregularities Definition Country Size Age Iraq 7120 13 % Max. 19.1% ≥2mm Mand. 15.1% Drummond (239) Max. 59.5% South 5744 12 Africa Cons et al. (257) ≥1mm Mand. 53.1% 15America 1337 8% 18 153 ≥2mm Chapter four Discussion 5.5.2 DISCREPANCIES IN OCCLUSAL CONTACT RELATIONSHIP 5.5.2.1 Maxillary overjet Anterior maxillary overjet indicates an antero-posterior deviation in Class II direction (238). The mean maxillary overjet of the sample was 2.9 mm, which was smaller than those found by Batayie Cons et al. (257) , Björk (272) , Haynes to the finding of Al-Huwaizi (225) (273) , Kinaan (14) , Abdulla (204) , (274) , but was near and Corruccini & Lee (275) as shown in (Table 5-7). Normal maxillary overjet ranged from 1 to 3 mm was found in 54.9% of the present sample. This is smaller than 61% of Al-Huwaizi (225) in his 13 years old Iraqi sample and 57.2% of Drummond (239) in his 13 years old South African sample. The increased overjet ≥6 mm was found only in 3.8% of the present sample and that was less than less than those found by Helm (243) , Cons et al. (257) , Haynes (273) and Corruccini et al. (276) . This is supports the theory of racial differences. Concerning gender differences, this study revealed that more boys than girls had an increased overjet, i.e. overjet more than 3mm and significantly more girls than boys had an edge-to-edge overjet (0mm overjet). This implies that 12-year-old boys have larger overjets and a higher prevalence of Class II malocclusions. Furthermore, 12-year–old Yemeni girls tend to have fewer overjets larger than 3mm and a higher prevalence of edge–to–edge overjet indicating a tendency towards Class III malocclusion. Brunelle et 154 Chapter four al. (268) Discussion studied 12- to 17-year-old American children, and found that the average overjet 3.3mm for boys was larger than the average overjet 2.8 mm for girls. This gender difference in the prevalence of maxillary overjet could be attributed to earlier maturation of the female group. The results indicated that significantly more 12-year-old children presented with a normal overjet in the early permanent dentition stage than 12-year-old children in the late mixed dentition stage. In other words, there is a higher prevalence of normal (1 to 3mm) overjet in 12-year-old children in the permanent dentition stage than in the mixed dentition stage. Certain occlusal indicators including overjet, naturally improves with age (268). These improvements may be due to the normal developmental changes and growth that occurs during the transition from the mixed dentition stage to the permanent dentition stage. The highest mean overjet was in Taiz and least in Aden. The difference between the six governorates for mean overjet was statistically significant. The results may indicate that significantly more 12-year-old school children who live in the coastal cities (Aden, Hadhramot, Hoddiedah) presented with an edge-to-edge anterior relationship and significantly less with an increased overjet. This suggests that Yemeni 12-year-old coastal cities inhabitants school children have a greater Class III tendency than a Class II tendency. 155 Chapter four Discussion Table 5-7: Reported mean overjet and prevalences of increased overjet. Author Batayie (14) Sample Results of overjet Country Size Age Mean ≥6mm Jordan 200 13 3.6 mm 6.0% 17.3% Whites 611 Kelly et al. (188) America Foster & Day (189) England 1000 1112 Farah (192) Iraq 101 910 3.74 mm Abdulla (204) Iraq 200 13 3.55mm Mohlin (212) Sweden 272 2045 Al-Huwaizi (225) Iraq 7120 13 Al-Alousi et al. (235) Iraq 952 1624 Increased OJ=28.5% South Africa 5744 12 2.2% %(OJ >6mm) Helm (243) Denmark 1700 918 15.9% (M) Cons et al. (257) America 1337 1518 3.66mm Björk (272) Sweden 12 4.1mm 20 3.4mm Haynes (273) England 1185 1112 3.84mm Iraq 250 England 236 Drummond (239) Kinaan (274) Corruccini & Lee (275) Corruccini et al. (276) 722 China India 1112 265 156 1216 13.5% Blacks 47%(>3mm) 10.7% (OJ 6-8mm) 4.3%(OJ ≥9mm) 9.0% 10% 11.3 mm 10.0% (OJ 6-8mm) 1.3%(OJ ≥9mm) 12.5% (F) 11.8% 15.4%(4.1%≥9mm) 3.43mm 3.72mm 3.2mm 7.9 Chapter four Discussion 5.5.2.1 Anterior mandibular overjet Anterior mandibular overjet, indicative of Class III malocclusion or anterior crossbite, is much less frequent with an occurrence of only 10.7% in the sample. The mandibular overjet ranged from 1mm to 5mm). According to Proffit et al. (107) a reverse overjet of 1mm to 3mm, suggesting a great treatment need occurs in 10% of the children. A reverse overjet of more than 3.5 mm, suggesting a very great treatment need occurs in almost less than one per cent of the children. The prevalence of mandibular overjet in this study was much higher than what was found by Batayine (14) and Al-Huwaizi (225) in their Jordanian and Iraqi samples respectively, but was near to the findings of Farah (192) and Drummond (239) as shown in (Table 5-8). The differences observed in (Table 5-8) between the prevalence of mandibular overjet of the present study and those reported by other investigators is difficult because of the differences in the age of the sample, criteria and method used to assess mandibular overjet in addition to possible racial variation. Concerning gender differences, this study revealed statistically insignificant difference between the two genders. This is coincident with the finding of Al-Huwaizi (225) . The results indicate that anterior mandibular overjet i.e. Class III malocclusion or anterior crossbite, is more prevalent in the late mixed dentition stage than in the early permanent dentition stage. 157 Chapter four Discussion These improvements are due to normal developmental changes and growth that occur during the transition from the mixed dentition stage to the permanent dentition stage. Table 5-8: Reported prevalences of mandibular overjet. Author Batayie (14) Foster & Day (189) Farah (192) Ingervall et al. (202) Sample Results of overjet Country Size Age Jordan 200 13 6% England 1000 1112 4.9% Iraq 101 910 10.9% 2145 3% Sweden Abdulla (204) Iraq 200 13 5% Al-Huwaizi (225) Iraq 7120 13 5.5% Drummond (239) South Africa 5744 12 10.4% Scotland 765 12 5.9% 12 8% 1112 3.2% Hill (258) Office of Population Censuses and Surveys (259) Britain Haynes (273) England 1185 Kinaan (274) Iraq 250 England 236 158 1112 4.3% 8% Chapter four Discussion 5.5.2.3 Vertical anterior openbite In the present study 8.3% of the children presented with anterior openbite. The size of the anterior openbite ranged from 1 to 5mm. In a malocclusion study in Nigeria, on 12- to 13-year-old children, Otuyemi et al. (173) reported that anterior openbite is a common malocclusion trait, and that it occurs in 10.2 % of the rural and urban Nigerian communities. Proffit et al. (107) classified an openbite of 0 to 2 mm as a moderate problem, an openbite of 3 to 4 mm as a severe problem and an openbite larger than 4 mm as extreme. Brunelle et al. in a study in the United States a moderate anterior openbite according to the classification by Proffit et al. (107) occurred in 2.8%, severe openbite occurred in 0.5% and extreme openbite occurred in 0.2% of the 12- to 17-year-old American population (268). The results of the present study show that a moderate anterior openbite occurred in 6.0% of the sample, a severe openbite in 2.0% and an extreme openbite occurred in 0.3 %, which was close to that reported by Abdulla Oreland et al. Batayine (277) (14) and Lavelle , Salonen et al. Otuyemi et al (204) , Drummond (239) , (278) ; but higher than that of (194) , and Al-Huwaizi (225) and less than (173) . This difference may be attributed to racial differences, different criteria and measurement methods together with the varying prevalence of bad oral habits (mainly digit sucking) which have a major role on anterior openbite. 159 Chapter four Discussion Considering gender differences, statistically insignificant difference in the distribution of anterior openbite between males and females were recorded in this age group in Yemen. This finding disagrees with that of Al-Huwaizi (225) and Drummond (239) ; who found that anterior openbite is more prevalent among females, but it is also worth mentioning that in the present study anterior openbite was also more prevalent among females than males. Anterior openbite is more prevalent in the late mixed dentition stage than in the early permanent dentition stage especially among females compared to males. These improvements may be due to normal developmental changes and growth that occurred during the transition from the mixed dentition stage to the permanent dentition stage and could be attributed to earlier maturation of the female group. This result contradicts with that of Drummond found statistically (239) ; who insignificant difference between the two dentition stages. The results also haved indicated that significantly more 12year-old school children who live in the coastal cities (Aden, Hadhramot, Hoddiedah) present with more vertical anterior openbite compared to 12-year-old school children who live in the mountain's cities (Ibb, Sana'a, Taiz). 160 Chapter four Discussion Anterior openbite is a lack of vertical overlap between any of the opposing pairs of incisors (32) . Anterior openbite reflects discrepancies in the vertical plane of space. As a child becomes older, it is more likely that malocclusion in the vertical plane of space, is related to skeletal jaw proportions and not just to displacement of the teeth (238). This may suggest that 12-year-old Yemeni coastal cities inhabitants school children have a greater tendency to discrepancies in the vertical plane of space than Yemeni 12-yearold mountain's cities inhabitants school children. 5.5.2.4 Antero-posterior molar relation The majority of the sample 69.4 % presented with a normal molar relationship, and this figure fell within the range of previously given prevalences 40%-86.8% as shown in (Table 5-9). It was also comparable to the figures given by several authors; ElMangoury & Mostafa (11) et al.(184), Salonen et al. Corruccini et al. (281) Savara (282) (276) , Batayine (14) , Massler and Frankel (74), Ast (194) , Helm , Al-Huwaizi (243) , Haralabakis (225) , Korkhaus (283) Muurray , Garner and Butt (379) ; Krogman (253) (280) , Telle (284) . Of the affected group 19.8% presented with a half a cusp displacement and 10.8% presented with a full cusp displacement. Considering gender differences, there is statistically significant difference showing more girls compared to boys with a normal molar relationship. This finding is in agreement with that of Drummond (239) , but it contradicts with that of Al-Huwaizi 161 (225) ; who Chapter four found Discussion statistically insignificant difference between the two genders. The distribution of antero-posterior molar relation showed no statistically significant relation with residence. This finding is in agreement with that of Ast et al. Salonen et al. (194) (184) and Al- Huwaizi (225) . While found that abnormal molar relation was more in urbans than rurals, and the result was statistically significant. 162 Chapter four Discussion Table 5-9: Reported prevalences of increased overjet antero-posterior molar relation. Author Sample Results (%) Country Size Age Normal Abnormal Libya 479 1012 77 23 El-Mangoury & Mostafa (11) Eygpt 501 1824 67.6 32.4 Batayie (14) Jordan 200 13 74 26 Massler & Frankel (74) America 2758 14 72.7 27.3 Ast et al. (184) America 1413 1518 74.6 25.4 Foster & Day (189) England 1000 1112 44.3 55.7 Salonen et al. (194) Sweden 669 ≥20 71.2 28.8 Abdulla (204) Iraq 200 13 75.5 24,5 Al-Huwaizi (225) Iraq 7120 13 72.7 27.3 Al-Alousi et al. 235 Iraq 952 1624 86.8 13.2 South Africa 5744 12 55.5 44.5 Helm (243) Denmark 1700 9-18 71.2 28.8 Garner and Butt (253) American Blacks 1216 71 29 75.3 24.7 Gardiner (10) Drummond 239 Kenya Cons et al. (257) America 1337 1518 62 38 India 265 1216 71.4 28.6 Korkhaus (278) Germany 1000 14 73.2 26.8 Krogman (280) American Whites 586 6.512.5 73.9 26.1 Norway 2349 7-8 71.4 28.6 Savara (282) American Whites 2774 1417 71.2 28.8 Lew et al. (285) Australian Chinese 1050 1214 65.9 34.1 Corruccini et al. (276) Telle (281) 163 Chapter four Discussion 5.6 ORTHODONTIC TREATMENT NEED OF MALOCCLUSION The lowest DAI score registered in this study was 13 and the highest was 46, and the most commonly registered DAI score was 23 (9.8% of sample). The only published studies presenting detailed DAI score distribution was that of Jenny et al. a later paper Jenny et al. (196) (193) published in more detail in and that of Al-Huwaizi (225) . The former study, showed that the lowest DAI score registered was 15 and the highest was 66, and the most commonly registered DAI score was 19 about 9.3% followed by 21 about 6.6%, while the later showed that the lowest DAI score registered was 13 and the highest was 65, and the most commonly registered DAI score was 21 about 13.1%. This result of the present investigation showed that the Yemeni, American and Iraqi samples had comparable median, showing that the DAI score could be used on the Yemeni population with relatively the same precision as on the American population on whom it was constructed. According to the DAI scores, 63.4% of the sample were found to have no or slight treatment need, 17.7% may need elective treatment, for13.0% treatment may be highly desirable, and 6.0% with very severe (handicapping) malocclusion were treatment is mandatory. When comparing these results with those found by others (Table 5-10) the Yemeni sample seems to have lower orthodontic treatment need than that of samples taken from American Whites, Native Americans, 164 New Zealanders or Chapter four Discussion Japanese. However, Otuyemi et al. (173) concluded that his Nigerian sample had a lower treatment need than that of the present study. However these comparisons require more rigorous investigations with careful matching design. DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found more Ibb and Sana'a followed by Hoddiedah, Aden, Taiz and Hadhrmot. Since, there is no previous local study so direct comparison was not possible. Table 5-10: Reported orthodontic treatment need using DAI. Sample Author Mean DAI scores (%) DAI Country Size Jenny & Cons (171) America 7500 12-17 45.8 25.2 Otuyemi et al. (173) Nigeria 703 12-18 77.4 13.4 23 22 22 33 Johnson & Harkness (174) New Zeland Age 10 13-25 26-30 31-35 ≥36 15 score 14 9.2 Ansai et al. (178) Japan 409 15-18 32 21 25 22 30.5 Jenny et al. (193) American White 1337 15-18 46 26 15 13 26.53 Native Americans 485 12-17 19 26 25 30 31.82 1306 15-18 45.5 23.6 15.5 15.2 Jenny et al. (196) America Al-Huwaizi (225) Iraq 6957 13 65.8 16.8 10.2 7.2 24.25 Yemen 3003 12 63.4 17.7 13 6.0 24.86 Present study 165 Chapter four Discussion In the year 2004, there were 421,776 Yemenis aged 12 years. About 6.0% of those children were estimated by the results of the present study have very severe handicapping malocclusion which needs mandatory orthodontic treatment which means that roughly about 25,300 children aged 12 years must be urgently treated every year to control handicapping malocclusion among the age group. This is a very large number of orthodontic patients and hence a plan should be set and carefully executed by the Ministry of Health to meet this need. 5.6.1 ORTHODONTIC TREATMENT NEED BY GENDER DAI scores of 31 and more where there is sever malocclusion and treatment is highly desirable or mandatory were found more prevalent in females than males, while DAI scores of 13 to 25 where there is no treatment need or slight need were found more prevalent in males 65.3% than females 60.9%. This gender difference in the DAI scores should be interpreted with caution. As observed earlier significant differences occur in the proportional distribution of DAI categories in the mixed dentition stage and the permanent dentition stage. The results of the present study have also indicated that there are more boys in the mixed dentition stage than girls. The differences in dental development between males and females could therefore contribute to this difference in the DAI. 166 Chapter four Discussion 5.6.2 ORTHODONTIC TREATMENT NEED BY RESIDENCY DAI scores where there is severe malocclusion and treatment is highly desirable or mandatory were found more in the urban sample 20.1% than in the rural sample 17.8%. This finding is in agreement with that of Ansai et al. with the findings of Al-Huwaizi (225) (178) , while it contradicts who found that in Iraq, rural children had significantly higher DAI scores compared to urban children and this may be attributed to age group, sample size in addition to some genetic and environmental differences. In general, no differences were observed in the prevalence of malocclusion in the different location types i.e. urban and nonurban schools (p>0.05). In other words, the prevalence of malocclusion in the tow setting does not differ significantly. The results of the present study may therefore suggest that the provision of orthodontic services for the rural and urban areas should not be different, except for the demand factor that may be more among urban inhabitants compared to rural dwellers. 5.6.3 ORTHODONTIC TREATMENT NEED BY EMPLOYMENT STATUS OF PARENTS The prevalence of malocclusion employment according to the status of the parents does not differ significantly (p>0.05). If employment status of the parents is used as an indicator of the socio-economic background, the results suggest that socioeconomic status does not influence malocclusion. 167 the prevalence of Chapter four Discussion From the total children, 36.7 % in present study were found to have a dental appearance that requires orthodontic treatment, ranging from ‘selective’ to ‘mandatory’. At the cut-off point of 32 to demarcate priority of orthodontic treatment, 19.0 % presented with severe and handicapping malocclusion, requiring ‘definite’ and ‘mandatory’ treatment. Compared to the dental appearance of Australian, New Zeeland and Malaysian subjects, Yemeni children were found to have better dental aesthetics and consequently a lower need for orthodontic treatment. Malocclusion as defined in this study was found to be significantly associated with the different governorates of Yemen, gender and dentition stage, but not with location type or employment status of parents. The results of this study have indicated a high prevalence of malocclusion in 12-year-old Yemeni children. These findings established reliable base-line data regarding the prevalence, distribution and severity of malocclusion as well as useful epidemiological data on the orthodontic treatment needs of 12year-old children in selected rural and urban areas in Yemen. At present, there is no doubt that many children with severe and handicapping malocclusion are not receiving adequate orthodontic treatment. As both the general dental health and socio-economic status of the population of Yemen improve, it is more likely that the number of children seeking orthodontic treatment will increase. This possible increase in patients seeking orthodontic care and the already high prevalence of malocclusion 168 Chapter four Discussion necessitate the careful planning of adequate orthodontic services in Yemen. For orthodontic problems, prevention is unlikely to be effective because malocclusion changes only a little with lower caries rates and tooth loss as general dental health improves and specific prevention measures for alignment or occlusal problems do not exist at present. ‘Prevention ‘of malocclusion is possible in only a few special circumstances. ‘Interceptive’ treatment can be very helpful in reducing the severity of the problems but rarely is so successful that later treatment becomes unnecessary. Orthodontic services should therefore be comprehensive, delivering appropriate treatment in response to specific situations, resulting in the efficient treatment of non-skeletal and skeletal problems. Because no differences were found in the prevalence of malocclusion between the different location types, it would appear that the type of orthodontic services needed at the different location types in Yemen should not be different. From the results of present investigation and other studies conducted elsewhere using the DAI it appears that the prevalence and treatment need are slightly higher for younger children than for older groups. This inverse relationship between chronological and DAI findings needs to be taken in consideration when using the DAI to plan orthodontic services. The use of dentition stage rather than chronological age as inclusion criteria for surveys using the DAI also needs to be explored. 169 Conclusions CONCLUSION 5. 1- The presence of malaligned teeth was reported by 29.7% of the sample, being more in female and more in Sana'a and Aden. The most prevalent reported types of malaligned teeth were crowded and protruded teeth. 2- Of the children who stated that they have malaligned teeth, 61.3% thought that it affects their appearance, 6.8% affects chewing, and 7.7% affects speech. 3- The most common reasons for not seeking orthodontic treatment was don't know the thought that treatment is not important or not possible 61.8% and fear of pain or tooth extraction 23.7%. 4- The mean missing visible teeth of the sample was 0.12 being higher in females than males. 5- Crowding in the incisal segment was found in 31.5% of the sample, being more in the late mixed dentition stage than in the early permanent dentition stage, but not related to gender. 6- Spacing in the incisal segment was found in 24.3% of the sample, being not related to gender or residency. 7- A maxillary central diastema (>2 mm) was found in 1.8% of the sample with a mean of 0.23 mm, being more prevalent in the late mixed dentition than in the early permanent dentition. 8- The mandibular anterior region showed highest prevalence of irregularities 43.2% than maxillary anterior region 37.3%; being more in urban children than rural ones. 169 Conclusions 9- The mean overjet of the sample was 2.9 mm being higher in Taiz and Hoddiedah. Increased overjet, i.e. overjet more than 3 mm was more in boys than girls, while edge-to-edge overjet (0 mm overjet) was more in girls than boys. 10- Anterior mandibular overjete was found in 10.7% of the sample, being more in the late mixed dentition stage than in the early permanent dentition stage, but not related to gender and residency. 11- Vertical anterior openbite was found in 8.3 % of the sample, females had a higher mean of vertical anterior openbite (0.19 mm) than males (0.14 mm). 12- Normal antero-posterior molar relationship was found in 69.4% of the sample and abnormal antero-posterior molar relationship was found in 30.6% (19.8% half a cusp displacement and 10.8% full cusp displacement) 13- The DAI score ranged between 13 and 46 with a mean of 24.89. 14- According to the DAI scores, 63.4% of the sample were found to have no or slight treatment need, 17.7% need elective treatment, for 13.0% treatment is highly desirable, and 6.0% with very severe (handicapping) malocclusion mandatory. 170 where treatment is Conclusions 15-Highly desirable or mandatory treatment need (DAI≥31) was found significantly more in Ibb, Sana'a and Hoddiedah; being more in females than males, but not related to residency or employment status of the parents. 16-In all of Yemen, it was estimated that roughly about 25,300 children aged 12 years must be urgently treated every year to control handicapping malocclusion. 171 Recommendations RECOMMENDATIONS From the results of the present study we may recommend the following:1. Extend this national cross-sectional study to: a- Include younger and older age groups. b- Follow up the sample at 15, 17, 19, 21 and above years of age to study the sample longitudinally. c- Use cast models for normal occlusion individuals to measure arch dimensions. d- Use of radiographic examination to detect impacted, supernumerary and congenitally missing teeth. e- Use cephalometric x-rays to study the differences in skeletal types. 2. Use the present data as a baseline for determining the manpower and resources needed to perform the required treatment. 3. Formulate a DAI equation by the use of perception of Yemeni children to perform a Yemeni DAI equation. 4. Use of other treatment need indices (as IOTN) in public surveys and comparing them with the DAI. 5. Use of the next national census for epidemiological registration of the subject's awareness of his/her own occlusion and other dental and medical issues. 6. 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Doctoral Thesis, Center for Study of Child Growth and Development, University of Helsinki, 1970 [Cited by: Graber et al. 101 206 ]. Appendices Appendix 1: General and personal information registration form. I. General information: / Date: /200 Serial No. Governorate: Urban Rural Location: School name: Gender: Male Female Class: II. Personal information: Name: Employment status of parents: Birth: Employed Traumatic or surgical defect: Description: Facial asymmetry: Cleft lip and/or palate: 207 / / / 199 /199 Unemployed Appendices Appendix 2: Questionnaire Form ﻋﺯﻴﺯﻱ ﺍﻟﻁﺎﻟﺏ /ﺍﻟﻁﺎﻟﺒﺔ ﻀﻊ ﺇﺸﺎﺭﺓ )ﺼﺢ(ﻋﻠﻰ ﺍﻟﺠﻭﺍﺏ ﺍﻟﺫﻱ ﺘﺨﺘﺎﺭﻩ ﻤﻥ ﻜل ﺴﺅﺍل: -1ﻫل ﺘﻌﺘﻘﺩ ﺒﺄﻥ ﺃﺴﻨﺎﻨﻙ ﻏﻴﺭ ﻤﻨﺘﻅﻤﺔ ﺃﻭ ﺘﺘﻼﻗﻰ ﺒﺼﻭﺭﺓ ﺨﺎﻁﺌﺔ؟ ﺃ( ﻨﻌﻡ ﺝ( ﻻ ﺃﻋﻠﻡ ﺏ( ﻜﻼ -2ﺇﺫﺍ ﻜﺎﻨﺕ ﺃﺴﻨﺎﻨﻙ ﻏﻴﺭ ﻤﻨﺘﻅﻤﺔ ،ﻓﻬل ﻫﻲ: ﺏ( ﺒﻴﻨﻬﺎ ﻓﺭﺍﻏﺎﺕ)ﻤﺘﺒﺎﻋﺩﺓ( ﺃ( ﻤﺘﺯﺍﺤﻤﺔ ﺩ ( ﻤﻠﺘﻭﻴﺔ ﺃﻭ ﻤﻨﺤﺭﻓﺔ ﻋﻥ ﻤﻜﺎﻨﻬﺎ ﺍﻟﺼﺤﻴﺢ ﺝ( ﺒﺎﺭﺯﺓ ﺇﻟﻰ ﺍﻷﻤﺎﻡ -3ﺇﺫﺍ ﻜﺎﻨﺕ ﺃﺴﻨﺎﻨﻙ ﻏﻴﺭ ﻤﻨﺘﻅﻤﺔ ،ﻓﻬل ﻴﺅﺜﺭ ﺫﻟﻙ ﻋﻠﻰ : ﺃ( ﺍﻟﻤﻨﻅﺭ ﺝ( ﺍﻟﻨﻁﻕ ﻭﺍﻟﻜﻼﻡ ﺏ( ﻤﻀﻎ ﺍﻟﻁﻌﺎﻡ -4ﺇﺫﺍ ﻜﻨﺕ ﺘﻌﺘﻘﺩ ﺒﺄﻨﻙ ﺘﺤﺘﺎﺝ ﻟﻌﻼﺝ ،ﻓﻠﻤﺎﺫﺍ ﻟﻡ ﺘﻌﺎﻟﺞ ﺃﺴﻨﺎﻨﻙ؟ ﺏ( ﻜﻠﻔﺔ ﺍﻟﻌﻼﺝ ﻋﺎﻟﻴﺔ ﺃ( ﺘﻌﺘﻘﺩ ﺃﻥ ﻋﻼﺠﻬﺎ ﻏﻴﺭ ﻤﻤﻜﻥ ﺩ( ﻻ ﺘﻌﺘﻘﺩ ﺃﻥ ﻋﻼﺠﻬﺎ ﻤﻬﻡ. ﺝ( ﺘﻌﺘﻘﺩ ﺃﻥ ﺍﻟﻌﻼﺝ ﻴﺴﺒﺏ ﺍﻷﻟﻡ ﻫ( ﺴﺒﺏ ﺃﺨﺭ )ﺍﺫﻜﺭﻩ ﺭﺠﺎﺀ(: .................................................................................................. -5ﻫل ﺃﺠﺭﻴﺕ ﺘﻘﻭﻴﻡ ﻷﺴﻨﺎﻨﻙ ﻓﻲ ﺍﻟﺴﺎﺒﻕ؟ ﺃ( ﻨﻌﻡ ﺏ( ﻜﻼ -6ﻫل ﻴﺠﺭﻯ ﻟﻙ ﻋﻼﺝ ﺘﻘﻭﻴﻡ ﻷﺴﻨﺎﻨﻙ ﺤﺎﻟﻴﺎ؟ ﺃ( ﻨﻌﻡ ﺏ( ﻜﻼ -7ﻫل ﻗﻠﻌﺕ ﺃﻱ ﻤﻥ ﺃﺴﻨﺎﻨﻙ ﺍﻟﺩﺍﺌﻤﺔ ﻟﺘﺤﺴﻴﻥ ﻤﻨﻅﺭ ﺃﺴﻨﺎﻨﻙ؟ ﺃ( ﻨﻌﻡ ﺏ( ﻜﻼ 208 Appendices Appendix 3: Treatment need registration form for the Dental Aesthetic Index (DAI) (from Cons et al., 1986). DAI component 0 1 2 3 Score Weight Sum Constant 13 Missing visible mandibular and maxillary incisor, canine and premolar teeth (No. of teeth) Crowding in the incisal segment (Number of crowded segments 0,1 or 2) Spacing in the incisal segment (Number of crowded segments 0,1 or 2) 6 1 1 4 Maxillary diastema (in mm) 3 5 Largest maxillary anterior irregularity (in mm) 1 6 Largest mandibular anterior irregularity (in mm) 1 7 Anterior maxillary overjet (in mm) 2 8 Anterior maxillary overjet (in mm) 4 9 Vertical anterior open bite (in mm) 4 10 Antero-posterior molar relation (0=normal, 1= ½cusp, 2=full cusp) Total (add lines 0 through 10) 209 3
