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RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES
BANGALORE, KARNATAKA
ANNEXURE II
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1.
Name of the Candidate
Address
DR . PUSHPALATHA. C.V.
POSTGRADUATE STUDENT IN THE
DEPARTMENT OF ORTHODONTICS AND
DENTOFACIAL ORTHOPEDICS,
K.L.E. SOCIETY’S INSTITUTE OF DENTAL
SCIENCES, # 20,YESHWANTPUR SUBURB,
TUMKUR ROAD, BANGALORE -22.
2.
Name of the Institution
K.L.E. SOCIETY’S INSTITUTE OF DENTAL SCIENCES,
BANGALORE-22.
3.
Course of the Study and Subject
MASTER OF DENTAL SURGERY IN
ORTHODONTICS AND DENTOFACIAL
ORTHOPEDICS
4.
5.
Date of Admission of Course
Title of the Topic:
APRIL 2011
APPLICABILITY OF BOLTON’S RATIOS TO A
SAMPLE OF SOUTH INDIAN POPULATION
1
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Brief Resume of Intended Work
6.1 Need For The Study
The important objectives of orthodontic treatment are to achieve excellent occlusion
with Class I molar and canine relationship, normal overbite and overjet. Interarch tooth width
proportion is an important factor in achieving these objectives. Tooth size is actually the “seventh
key ” to normal occlusion.1 Bolton’s analysis is widely used to assess tooth size discrepancy that
helps in achieving excellent finish at the end of the treatment.
Tooth size discrepancy may vary in different population and ethnic groups. Gender
differences have also been observed. Although there are various studies on Bolton’s analysis in
different population and ethnic groups, few studies have reported tooth size discrepancies in Indian
population. There is no published study on Bolton’s ratios in a South Indian population. Hence the
aim of the study will be to assess the Bolton’s tooth size discrepancy in a sample of south Indian
population.
6.2 Review of Literature:
Bolton2, 3 (1958, 1962) studied the maxillary and mandibular tooth size proportions
on 55
patients with excellent occlusion. The casts were selected from a large number of excellent
occlusions, most of which were treated orthodontically(non-extraction). The sample consisted of 44
orthodontically treated and 11 untreated subjects. The maximum mesiodistal widths of all teeth
except second and third molars were measured on each cast. He established ideal ratios of anterior
and overall maxillary and mandibular tooth size. The anterior and overall ratios were calculated by
using the formulae. The mean value of anterior ratio was 77.2 ±0.22. The mean value of overall ratio
was 91.3 ±0.26.
Prasad KK and Valiathan A4 (1994) compared norms for Indian and Chinese using Bolton’s
index. Fifty cases each of normal Angle’s Class I occlusion were selected and measurements were
carried out on casts. The overall ratio for Indian sample was 93.46 and for Chinese sample it was
90.84. No significant difference was apparent in the two groups.
Smith SS, Buschang PH, Watanabe E5 (2000) studied
interarch tooth size relationships of
three populations - whites, blacks or Hispanics. They collected pre-orthodontic casts of 180 patients
and digitized forty-eight mesiodistal contact points on each model. They
observed that the
segments of males were significantly larger than females; the overall and posterior ratios were also
significantly larger in males than in females.
2
They concluded that interarch tooth size relationships are population and gender specific. Bolton
ratios apply to white females only; the ratios should not be indiscriminately applied to white males,
blacks or Hispanics.
Bernabe E, Major PW and Flores-Mir C6 (2004) studied tooth-width ratio discrepancies in a
sample of Peruvian adolescents. Two hundred children were selected and their casts were measured
with a sliding caliper and a vernier scale. No significant differences were found in anterior and total
tooth size sums according to sex. Then combined male and female anterior and total ratio was
calculated. There were clinically significant tooth size discrepancies in almost one third of the
sample.
Al-Tamimi T and Hashim HA7 (2005) studied tooth-size ratios in a Saudi sample with Class I
normal occlusion. And compared tooth-size ratios between the present study and Bolton's study and
between genders. Dental casts and cephalometric radiographs of 65 subjects (37 males and 28
females) were used in this study. The age range was 18 to 25 years. They found that there were no
statistically significant differences between the mean values of the anterior ratio and the overall ratio
of the present study and the mean values reported by Bolton and also between genders. Further, the
results revealed a low correlation between the anterior ratio and the interincisal angle.
Paredes V, Gandia JL and Cibrian R8 (2006) did a study on Bolton ratio on Spanish
population. They used a digital method and measured the casts to the nearest 0.05 mm. The sample
consisted of 100 pairs of dental casts of Spanish subjects. They found out that twenty-one percent of
the subjects had a significant anterior discrepancy and five percent had a total discrepancy.
Differences between Spanish values and Bolton’s were significant.
Wedrychowska-Szulc B, Janiszewska-Olszowska J and Stepien P9 (2010) compared overall and
anterior Bolton ratios in different malocclusion groups with Bolton’s standards. The material
comprised of 600 pre-treatment study casts. Statistically significant differences were found for the
mean overall ratio when compared with the original Bolton norm for the whole study group, as well
as for patients with Class I and III malocclusions when the mean anterior ratio was compared with
the original Bolton norm. Significant differences were observed in all groups of malocclusions for
both genders. Discrepancies exceeding 2 SD were found in 31.2% of the studied population for the
anterior ratio when compared with Bolton’s norm. The highest mean values for anterior ratio were
in males with Class I (79.1) and Class III (80.1) malocclusions.
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Dhar HCS, Bora M 10 (2010) studied the applicability of the Bolton’s tooth size ratio to Assamese
population. Seventy Assamese subjects, having normal occlusion were selected. No statistically significant
differences were found among males and females for the anterior and overall ratios. The anterior ratio
was significantly higher from Bolton’s standard while the overall ratio was not. The anterior ratio showed
a statistically significant difference and was lower than the ratio found in the Han Chinese and Blacks. The
anterior ratio also showed a discrepancy from Bolton’s standard > 2SD in 27.14% of samples. The overall
ratio showed a deviation>2SD in only 7.14% of the samples from Bolton’s standard which indicates that
the majority of the samples are within 2 SD of Bolton’s mean overall ratio.
6.3 Aims and Objectives of the study:
The aim of the study is to assess the Bolton’s tooth size discrepancies in a sample of South Indian
population.
Objectives of the study :
1. To determine the Bolton’s anterior and overall ratios
2. To compare the ratios to Bolton’s norms
3. To determine gender differences
4. To test if any correlation exists between anterior and overall ratios
7.
Materials and Methods
7.1 Source of data
Subjects of South Indian ethnicity residing in Bangalore and patients of K.L.E Society’s
Institute of Dental Sciences, Bangalore.
.
7.2 Method of collection of data
Age : 12-35 yrs
Sample size: 50 (25 males and 25 females)
Type of study : Analytical cross sectional study
Period of study : 20 months
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Inclusion criteria

Subjects of South Indian ethnicity.

Angle’s Class I molar and canine relation with no or minimal crowding

Normal overjet and overbite

Fully erupted permanent dentition from first molar to first molar

Good quality of casts
Exclusion criteria

Cases with tooth agenesis

Cases with missing teeth or fixed partial dentures

Cases with gross restorations that can change the mesio-distal diameter of tooth

Cases with interproximal or occlusal wear of teeth

Cases with congenital defects and deformed teeth

Cases with spacing
Method
The sample will include both untreated and orthodontically treated dentitions (non-extraction).
Informed consent will be taken from the untreated subjects to participate in the study.
A total of fifty
good quality study casts will be collected. Maximum mesio-distal widths of all teeth excluding second and
third molar will be measured with a digital caliper to an accuracy of 0.01 mm. Anterior and Overall ratio
for each cast will be calculated by Bolton’s formulae.
Sum mandibular 6 teeth
___________________
Sum maxillary 6 teeth
× 100 = Anterior ratio
Sum mandibular 12 teeth
_______________________
Sum maxillary 12 teeth
× 100 = Overall ratio
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Only five pairs of casts will be measured per day to prevent the visual fatigue.
In order to determine method error, the study models of ten randomly selected individuals will be
measured again two weeks later by the same examiner. The method error will be analysed by using
Dalhberg’s formula.
The mean, standard deviation, co-efficient of variation for anterior and overall ratios will be calculated.
Student’s t-test will be used to compare the anterior and overall ratio in males and females. Pearson’s
correlation test will be used to determine the correlation between anterior and overall ratio.
Material

Fifty study casts

For measurement of data - A Digital caliper of 0.01 mm accuracy will be used.
Statistical tests that will be used
1. The arithmetic mean and standard deviation and coefficient of variation of anterior and overall
ratios will be calculated.
2. Student’s t-test will be used to compare anterior and overall ratios in males and females.
3. Dahlberg’s formula for calculating method error.
4. Pearson’s correlation test to find out any correlation between anterior and overall ratios.
7.3 Dose the study require any investigation or interventions to be conducted on patients or other
humans or animals? If so please describe briefly
No.
7…4 Has ethical clearance be obtained from your institution in case of 7.3?
Yes, Obtained.
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List of References
1. McLaughlin RP, Bennett JC, Trevesi H: Systemised orthodontic
treatment
mechanics,Spain,
2004, Mosby.
2. Bolton WA. Disharmony in tooth size and its relation to the analysis and
treatment of
malocclusion. Angle Orthodontist 1958; 28: 112–130.
3. Bolton WA. The clinical application of a tooth-size analysis. Am J Orthod 1962; 48: 504-529.
4. Prasad KK, Valiathan A. Model analysis – Comparison of norms for Indian and Chinese using
Bolton’s index. Journal of Indian orthodontic society 1994; 25: 77-80.
5. Smith SS, Buschang PH, Watanabe E. Interarch tooth size relationships of 3 Populations. “Does
Bolton’s analysis apply?” Am J Orthod Dentofacial Orthop 2000; 117: 169- I74.
6. Bernabe E, Major P W, Flores-Mir C. Tooth-width ratio discrepancies in a sample of Peruvian
adolescents. Am J Orthod Dentofacia Orthop 2004; 125: 361–365.
7. Al-Tamimi T, Hashim HA. Bolton tooth-size ratio revisited. World J Orthod 2005; 6: 289-295.
8. Paredes V, Gandia JL, Cibrian R. Do Bolton’s ratios apply to a Spanish population? Am J
Orthod Dentofacial Orthop 2006; 129: 428-430.
9.
Wedrychowska-Szulc B, Janiszewska-Olszowska J, Stepien P. Overall and anterio Bolton ratio in
Class I, II, and III orthodontic patients. European Journal of Orthodontics 2010; 32: 313–318.
10. Dhar HCS, Bora M. The applicability of the Bolton’s tooth size ratio to Assamese population.
Journal of Indian Orthodontic Society 2010; 44: e38 URL:http://www.jiosweb.org.
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10. Signature of the Candidate
11. Remarks of the Guide
SATISFACTORY
11.1 Name and Designation of Guide
DR. SUMITRA
PROFESSOR
DEPARTMENT OF ORTHODONTICS
AND ORTHOPEDICS
K.L.E. SOCIETY’S INSTITUTE OF
DENTAL SCIENCES, BANGALORE22
11.2 Signature
______
11.3 Co-Guide(if any)
______
11.4Signature
DR. S.E.SHEKAR
11.5 Head of the Department
PRINCIPAL AND H.O.D.
DEPARTMENT OFORTHODONTICS
AND DENTOFACIAL ORTHOPEDICS.
K.L.E. SOCIETY’S INSTITUTE OF
DENTAL SCIENCES, BANGALORE-22
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11.6 Signature
12.1. Remarks of the Chairman & Principal
This study can be done
12.2. Signature
DR. S.E.SHEKAR
PRINCIPAL
K.L.E. SOCIETY’S INSTITUTE OF DENTAL
SCIENCES, BANGALORE-22
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