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DISSERTATION – SYNOPSIS DR. SUMITHA SHETTY B. POSTGRADUATE STUDENT, A. J. INSTITUTE OF DENTAL SCIENCES, KUNTIKANA, MANGALORE. BATCH 2008-2009. Rajiv Gandhi University of Health Sciences, Karnataka, Bangalore ANNEXURE II PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION 1. Name of the Candidate SUMITHA SHETTY B. and address (in block letters) 2. A. J. INSTITUTE OF DENTAL SCIENCES, N.H.17, KUNTIKANA, MANGALORE-575004. Name of the institution A. J. INSTITUTE OF DENTAL SCIENCES . 3. Course of study and subject MASTER OF DENTAL SURGERY ORTHODONTICS 4. Date of admission to course 5. Title of the topic: 28.05.2008 EVALUATION OF CHANGES IN CRANIAL BASE MORPHOLOGY IN DIFFERENT MALOCCLUSIONS. 6. Brief resume of the intended work: 6.1 Need for the study Description and diagnosis of a malocclusion is the primary objective of the Orthodontist. In the assessment of Orthodontic problems involving anteroposterior malrelationship of the jaws, the problem is usually the result of size, form and position of the jaw. Despite the effects of head posture1, breathing mode2 or even spine position3 that have been shown to influence craniofacial morphology, cranial base flexion has been put forward to be a possible indicator of a skeletal malocclusion. Depending on the fact that the maxilla is connected with the anterior part of the cranial base and the rotation of the mandible is influenced by the maxilla, a relationship can be found between the cranial base variations and saggital malpositions of the jaw. Due to controversy in the current literature, the present study is done to investigate, in a cross-sectional sample, whether the cranial base flexure or shape of the cranial base could show morphological differences in skeletal class I, class II and class III malocclusions. 6.2 Review of literature: A cross-sectional retrospective study was carried out to investigate any possible differences in the shape and position of the cranial base in class I, class II and class III skeletal patterns. The results showed that there were no differences observed in anterior and posterior cranial base lengths and cranial base angles between the three malocclusions. However, cranial base inclinations were increased in class III malocclusions.4 A study was done to examine the contribution of cranial base angle in the four groups of malocclusion as classified by the British Standards Institute incisor classification. A total of 200 cephalometric radiographs of caucasian patients (50 for each malocclusion group, with an age range between 8-12 years) were selected for the study. Following linear and angular variables were calculated : Cranial base flexure, jaw position, skeletal pattern, dento-alveolar pattern, cranial base lengths and jaw lengths. Results showed that the cranial base flexure does not play a pivotal role in determining malocclusion. Jaw size, however, was significantly different between the main classes of malocclusion. The maxilla was found to be longer in class II subjects and the mandible longer in class III subjects.5 A longitudinal study was conducted to investigate skeletal features in patients with small and large cranial base angles at the age of 5 and 12 years. Subjects with large cranial base angle in the primary dentition demonstrated a skeletal class II tendency both at the initial observation and at the longitudinal follow up. The cephalometric variables indicated a constancy of the skeletal pattern during longitudinal follow-up. The relationship between cranial base flexure and skeletal pattern of the jaws seems to be established before the age of 5 years.6 A study was conducted to compare seven cephalometric measurements of the cranial base in subjects with class I and class II skeletal patterns at ages 1month, 2 years and 14 years. Results indicate that individuals with class II skeletal pattern do not have significantly more obtuse cranial base angle. In fact, this angle became more acute with age in both of the groups that were studied, with the greatest change occurring between 1 month and 2 years. No significant changes were found in this angle between 2 years and 14 years. The results indicate that these differences do not lie within the cranial base and thus lead us to look more precisely at the structural and growth differences of the maxilla and mandible.7 A study was done to examine the craniofacial patterns in class III, class II division 1 and class II division 2, malocclusions respectively. The results of the study were that the linear and angular dimensions of the cranial base tend to be smaller in class III malocclusions and to be larger in class II malocclusions when compared with a common control group of children with either normal occlusion or class I malocclusion. The variation of the cranial base stood out as the most consistent factor associated with anteroposterior malrelationships of the dental arches. It was concluded that the dimensions of the cranial base are a major factor in determining anteroposterior relationship of the jaw and the dental arches which must be taken into account in diagnosis and treatment.8 An investigation was done to analyze the growth mechanism of the cranial base on 243 Swedish boys ( first examined at the age of 12 and later at the age of 20). The material on which the investigation was based consisted of two series of standardized lateral head x-ray pictures. Results of the investigation were: The general growth pattern showed the cranial base was elongated virtually by frontal apposition in the glabella region, without any appreciable longitudinal, sutural increment of the anterior cranial fossa. The dorsal elongation of the cranial base, in the medial region due to the endochondral growth of the clivus, is accompanied by a dorsal displacement due to the sutural growth of the lateral regions of the cranial base and the brain case, forming the median and the posterior cranial fossae and a simultaneous lowering of these regions in relation to the anterior cranial fossa. There was on an average, an insignificant straightening of the cranial base and there was a virtually parallel lowering of the foramen magnum.9 6.3 6.3 Objectives of the study: To evaluate the following in skeletal class I, class II and Class III malocclusions: the differences in cranial base flexure anterior and posterior cranial base lengths cranial base inclinations. 7. Material and methods: 7.1 Source of data: Lateral cephalometric radiographs (pretreatment) of 75 patients, referred for treatment, to the Department of Orthodontics and Dentofacial Orthopaedics, A. J. Institute of Dental Sciences, Mangalore will be taken. 25 patients with skeletal class I, 25 patients with skeletal class II and 25 patients with skeletal class III will be selected for the study. The mean age group of the patients for the study will be 15±4. 7.2 Methods of collection of data(including sampling procedure, if any) Selection of teeth: Not applicable. Methodology: Lateral cephalometric radiographs of each subject will be taken with a digital panoramic and cephalometric system. All the subjects will be positioned in the cephalostat with the saggital plane at right angle to the path of x-rays with the Frankfort plane parallel to the horizontal, teeth in centric occlusion and lips relaxed. Following are the criteria used in selecting the patients for the study: Group 1 (n=25): skeletal class I malocclusion with an ANB angle of 2±2º, favorable over jet and overbite and minimal crowding of both arches. Group 2 (n=25): skeletal class II malocclusions with ANB angle of +5º or more, increased overjet. Group 3 (n=25): skeletal class III malocclusions with an ANB angle of −1º or less negative overjet. Patients with a history of any oral habit will be excluded from the study. All of the patients will be past pubertal growth spurt stage as assessed according to cervical vertebrae maturation index CV4 developmental stage and showed normal vertical growth pattern as determined by GoGnSN angle (GoGnSN=32±6) according to Steiner’s analysis.10 The radiographs will be traced and following landmarks will be used for cephalometric analysis: Point A (A), Point B (B), Sella (S), Nasion (N), Articulare (Ar), Basion (Ba), Gonion (Go), Gnathion (Gn), Porion (Po), Orbitale (Or). The following reference lines and angles will be used in this study: S-N, S-Ba, SNA, SNB, ANB, GoGn-SN, N-S-Ar, N-S-Ba, SN-FH, SBa-FH. 7.3 Does the study require any investigations or interventions to be conducted on patients or other humans or animals? If so, please. Describe briefly. Lateral cephalometric radiographs of patients will be required to do the study. 7.4 Has ethical clearance been obtained from your institution in case of 7.3? Yes. INVESTIGATION DESIGN Lateral cephalometric radiographs of 75 patients (pretreatment) will be taken Skeletal Class I (25) Skeletal Class II (25) Skeletal Class III (25) The following landmarks will be used for cephalometric analysis: Point A (A), Point B (B), Nasion (N), Articulare (A), Basion (Ba), Gonion (Go), Gnathion (Gn), Porion (Po), Orbitale (Or). Parameters that will be used are Angular measurements Saggital growth pattern: SNA, SNB, ANB. Vertical growth pattern: GoGn-SN. Linear measurements A-P cranial base inclinations : SN-FH SBa-FH. Cranial base flexure: N-S-Ar, N-S-Ba. Cranial base dimensions: S-N, S-Ba. Mean and standard deviations will be estimated for cephalometric variables in each group using ANOVA and TUKEY tests. Statistical analysis will be done using Statistical package for Social sciences software package (SPSS for windows, Version 15.0, Chicago, IL, USA). 8. List of References 1. Solow B, Tallgren A. Head posture and craniofacial morphology. Am J Phys Anthropol 1976;44:417-435. 2. Peltomäki T. The effect of mode of breathing on craniofacial growth-revisited. Eur J Orthod 2007;29:426-429. 3. Solow B, Sandham A. Cranio-cervical posture: a factor in the development and function of the dentofacial structures. Eur J Orthod 2002;24:447-456. 4. Palot OO, Kaya B. Changes in cranial base morphology in different malocclusions. Orthod Craniofacial Res.2007;10:216-221. 5. Dhopatkar A, Bhatia S, Rock P. An investigation into the relation between cranial base angle and malocclusion. Angle Orthod 2002;72:456-63. 6. Klocke A, Nanda RS, Kahl-Nieke B. Role of cranial base flexure in developing saggital jaw discrepancies. Am J Orthod Dentofacial Orthop 2002;122:386-91. 7. Wilhelm BM, Beck FM, Lidral AC, Vig KWL. A comparison of cranial base growth in class I and class II skeletal patterns. Am J Orthod Dentofacial Orthop 2001;119:401-5. 8. Hopkin GB, Houston WJB, James GA. The cranial base as an etiological factor in malocclusion. Angle Orthod.1968;38:250-5. 9. Bjork A .Cranial base development. Am J Orthod 1955;41:198-255. 10. Steiner C. C. Cephalometrics for you and me. Am J Orthod.1950;36:877-898. 11. Dibbets JMH. Morphological associations between the Angle classes. Eur J Orthod 1996;18:111-118. 12. Kasai K, Moro T, Kanazawa E, Iwasawa T. Relationship between cranial base and maxillofacial morphology. Eur J Orthod 1995;17:403-10. 13. Kerr WJS, Hirst D. Craniofacial characteristics of subjects with normal and postnormal occlusion. A longitudinal study. Am J Orthod Dentofacial Orthop 1987;92:207-12. 14. Jarvinen S. Saddle angle and maxillary prognathism: a radiological analysis of the association between the NSAr and SNA angles. Br J Orthod.1984;11:20913. 15. Anderson DL, Popovitch F. Lower cranial height vs craniofacial dimensions in Angles class II malocclusion. Angle Orthod 1983;53:253-60. 16. Kerr WJS. A method of superimposing lateral cephalometric films for the purpose of comparison: a preliminary report. Br J Orthod 1978;5:51-3. 17. Lewis AB, Roche AF. The saddle angle: constancy or change? Angle Orthod 1977;47:46-54. 18. Ricketts RM. Cephalometric analysis and synthesis. Angle Orthod 1961;31:141-56. 19. Renfroe EW. A study of the facial patterns associated with class I, class II division 1 and class II division 2 malocclusion. Angle Orthod 1948;18:12-5. 20. Solow B, Kreilborg S. Soft tissue stretching: a possible control factor in craniofacial morphogenesis. Scand J Dent Res 1977;85:505-7. 9. Signature of candidate 10. Remarks of the guide: Name & Designation of 11. (in block letters): DR. NILLAN SHETTY K. PROFESSOR DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS. 11.1 Guide: 11.2 Signature: 11.3 Co-Guide (if any) DR. ROHAN RAI PROFESSOR AND HEAD OF THE DEPARTMENT DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS. 11.4 Signature: 11.5 Head of Department 11.6 Signature 12. 12.1 Remarks of the Chairman & Principal: 12.2 Signature DR. ROHAN RAI DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS.