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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 8  |  Issue : 4  |  Page : 136-140

The applicability of Bolton's tooth size ratios for population-specific malocclusion


1 Department of Orthodontics and Dentofacial Orthopedics, Aditya Dental College, Beed, Maharashtra, India
2 Department of Orthodontics and Dentofacial Orthopedics, Bharti Vidyapeeth, Pune, Maharashtra, India

Date of Web Publication11-Oct-2017

Correspondence Address:
Zafar Iqbal Javed Iqbal Sayed
Flat No-1, A-Wing, Ground Floor, Parekh Nagar Society, Kurar Village, Malad (East), Mumbai - 400 097, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijor.ijor_35_17

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  Abstract 

Aims: This study aims to evaluate the Bolton ratio in Beed population in Maharashtra with different malocclusion.
Materials and Methods: Fifty study casts were taken from the patients undergoing orthodontic treatment, and individuals were divided into three groups: Group I (Angle's Class I, n = 25), Group II (Angle's Class II, n = 25), and Group III (mean of Group I and Group II).
Statistical Analysis Used: ANOVA and Tukey's test.
Results: A mean total Bolton ratio of 93.05 ± 5.87 and a mean anterior Bolton ratio of 81.08 ± 5.93 were found for the sample; significantly, higher mean anterior tooth ratios were found for Group I (Angle's Class I) patients (P < 0.03).
Conclusions: Mean anterior tooth size discrepancy for Angle Class I individuals was significantly greater compared to Bolton's mean anterior ratio.

Keywords: Angles Class I and Class II, Bolton's ratio, tooth size ratios


How to cite this article:
Sayed ZI, Doke AD. The applicability of Bolton's tooth size ratios for population-specific malocclusion. Int J Orthod Rehabil 2017;8:136-40

How to cite this URL:
Sayed ZI, Doke AD. The applicability of Bolton's tooth size ratios for population-specific malocclusion. Int J Orthod Rehabil [serial online] 2017 [cited 2018 Feb 22];8:136-40. Available from: http://www.orthodrehab.org/text.asp?2017/8/4/136/216509


  Introduction Top


To establish a population-specific Bolton's ratio for a particular sect of regional population is our aim to use the same as standard while calculation of Bolton's discrepancy adding more specificity to our study thereby enhancing our values.

Tooth size discrepancy is different among the sizes of the individual teeth.[1]

For ideal occlusion [2], teeth in both arches should be proportional in size; significant TSDs [3,4] prevent an ideal occlusion being produced at the end of orthodontic treatment.

Tooth size analysis was presented by Bolton in 1958, and the anterior segment ratio was derived to be 77.2% ± 0.22% and 91.3% ± 0.26% for the total arch ratio. Bolton's ratio has been suggested as the seventh “key” for an ideal occlusion, as it plays an important role for ideal occlusion.[2]

Overall, TSDs [5],[6],[7] relate to all teeth excluding permanent second and third molars, whereas anterior TSDs [8] involve the six anterior teeth from the left side canine to the right side.

Studies have found smaller tooth size ratios (TSRs) in women than in men, but the differences of 0.6%–1.0% were not significant.[9]

There are various methods to measure the mesiodistal width of teeth such as conventional fine pointed caliper or digital caliper, measuring photocopies of casts with a caliper and divider.[10]

The purpose of this study was to evaluate the Bolton ratio in Marathwada with different malocclusion groups.


  Materials and Methods Top


This cross-sectional study[11] was carried out at Aditya Dental College, Beed, Maharashtra.

Orthodontic diagnosis and treatment planning require the patient's history, extra- and intra-oral examination, and analysis of diagnostic records comprising of orthodontic photographs, radiographs, and study casts [Figure 1].
Figure 1: Bolton's case history format

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Tooth size is the sum of the mesiodistal width of the maxillary and mandibular teeth, which is measured in this study on the prepared study casts.

A thorough examination of all the study casts was done. All impressions of orthodontic patients were taken with a fast setting alginate.

Impressions were poured with an orthodontic plaster, after which they were trimmed. Fifty out of 80 study casts (Age: female [14.2 ± 1.5 years], male [13.9 ± 2.3 years]) were filtered based on the inclusion and exclusion criteria [Table 1].
Table 1: Inclusion and exclusion criteria for the study conducted

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Study casts were further divided into three groups: Group I (Angle's Class I, n = 25), Group II (Angle's Class II, n = 25), and Group III (a mean of Group I and Group II, n = 25) according to Angle's classification of malocclusion [Figure 2].
Figure 2: Group I and II each consisting of 25 individuals each

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The mesiodistal widths of all maxillary and mandibular teeth from right permanent first molar to left permanent first molar were calibrated with the use of a divider [Figure 3].
Figure 3: Armamentarium

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The readings were used to calculate the anterior and total Bolton ratios and the data were analyzed.

Mean and standard deviation were calculated for anterior and total Bolton ratios for the whole sample and for all the three groups individually.

The ANOVA test was used to compare the three groups with each other and with the Bolton's proposed norms for total and anterior Bolton ratios. Tukey's test was also used for post hoc analysis.


  Results Top


Comparison of mean Bolton overall ratio among Group I population, Group II population, and Group III, respectively, is done using ANOVA F-test. ANOVA F-test is used to compare three or more sample means. No statistical difference (P > 0.05) was found among three malocclusion groups in relation to Bolton overall ratio [Table 2].
Table 2: Comparison of mean Bolton overall ratio among Group I (Angle's Class I malocclusion) population, Group II (Angle's Class II) population, and Group III (mean of sample population), respectively (using ANOVA F-test)

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ANOVA was followed by Tukey's post hoc analysis to understand individual comparison among three malocclusion groups. No significant difference (P > 0.05) was found in mean Bolton overall ratio across all the three individual comparisons (Group I vs. Group II, Group III vs. Group III, Group II vs. Group III) [Table 3].
Table 3: ANOVA followed by Tukey's post hoc test (for multiple individual comparison)

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Comparison of mean Bolton anterior ratio among Group I population, Group II population, and Group III, respectively, is done using ANOVA F-test. ANOVA F-test is used to compare three or more sample means. No statistical difference (P > 0.05) was found among three malocclusion groups in relation to Bolton anterior ratio [Table 4].
Table 4: Comparison of mean Bolton anterior ratio among Group I (Angle's Class I malocclusion) population, Group II (Angle's Class II) population, and Group III (mean of sample population), respectively (using ANOVA F-test)

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ANOVA was followed by Tukey's post hoc analysis to understand individual comparison among three malocclusion groups. Mean Bolton anterior ratio was significantly higher in Group I as compared to Group II (P< 0.05), while no significant difference was found in Group I as compared to Group III (P > 0.05) and in Group II as compared to Group III (P > 0.05) [Table 5].
Table 5: ANOVA followed by Tukey's post hoc test (for multiple individual comparison)

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Student's t-test is used to compare two sample means which are unpaired groups. Mean Bolton anterior ratio [8] was significantly higher in Group I as compared to Group II (P< 0.05) [Table 6].
Table 6: Comparison of mean Bolton overall ratio and mean Bolton anterior ratio, respectively, among Group I (Angle's Class I malocclusion) population and Group II (Angle's Class II) population (using unpaired t-test/student's t-test)

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A mean total Bolton's ratio of 93.05 ± 5.87% and a mean anterior Bolton's ratio of 81.08 ± 5.93% were found for the sample [Graph 1] and [Graph 2].



Significantly higher mean anterior tooth ratios were found for Group I (Angle's Class I) patients (P< 0.03) [Graph 3].




  Discussion Top


In our study, comparison was made between TSDs [12] of Class I and II patients on study cast based on Angle's classification of malocclusion. The mean total ratio for the whole sample was 93.05 ± 5.87 which is very close to Bolton's proposed ideal ratio. However, the anterior ratio for the whole sample was found to be 81.08 ± 5.93, which is higher than Bolton's proposed ideal ratio, which reflected a greater mesiodistal widths in the mandibular anterior segment in our population sample. In Group I patients, the mean total ratio calculated was 93.21 ± 5.23. Similarly, the total mean ratio calculated for Group II was 92.89 ± 6.41 and the mean anterior ratio calculated was 80.05 ± 5.18 which is close to Bolton's proposed ideal ratios. A significantly higher (P< 0.05) mean anterior ratio (82.21 ± 6.41) for Group I patients was found, and this reflects a tendency toward wider mesiodistal dimensions in the mandibular anterior segment in our study sample. There was a significant difference in the anterior tooth ratios between Group I and Group II patients. Uysal and Sari [13] compared interarch TSD in 150 untreated, normal occlusion individuals and 560 patients of four different malocclusion groups. A gender dimorphism was found in the normal individuals. All malocclusion groups showed significantly higher overall ratios than normal occlusion groups. However, no statistically significant difference was found between the malocclusion groups. Al-Khateeb and Abu Alhaija [14] found no statistically significant differences in Bolton's ratios between the different malocclusions. Their sample consisted of 140 orthodontic models of school children aged between 13 and 15 years of Jordanian origin. In this study, we found that Group I patients had higher mesiodistal width in mandibular anterior region and Group I includes Angle's Class I malocclusion patients. The results of the present study are in partial agreement with some of the above studies considering the fact that no significant difference was found between Bolton's norms and TSRs in Group I and Group II patients. The observation of this study was that, in Group I that includes Angle's Class I malocclusion, individuals showed a significantly higher anterior ratio, indicating wider mandibular teeth in Angle's Class I malocclusion or smaller teeth in the maxillary arch.


  Conclusion Top


Mean anterior TSD for Angle Class I individuals was significantly greater compared to Bolton's mean anterior ratio. There was relatively more tooth size excess in the mandibular anterior or smaller teeth in the anterior maxillary arch in selected samples of malocclusions (Marathwada population) as compared to Bolton's original sample of excellent occlusions.

Acknowledgment

I would like to thank entire staff members of Department of Orthodontics and Dentofacial Orthopedics, Aditya Dental College, Beed and Department of Orthodontics and Dentofacial Orthopedics, Bharti Vidyapeeth, Pune for helping us conduct this clinical examination process at both the colleges and guiding us through all the hurdles which befell upon us during the study.

I take this opportunity to thank my fellow mates Dr. Nikhat Naaz, Dr. Rafat Naaz, and Dr. Nadifa Sayyed for helping me out with the editing and record maintaining work; this would not have shaped if it were not for your relentless efforts. Thanks Mom and Dad above all.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Bolton WA. Disharmony in tooth size and its relation to the analysis and treatment of malocclusion. Angle Orthod 1958;28:113-30.  Back to cited text no. 1
    
2.
McLaughlin R, Bennett J, Trevisi H 2nd, editors. Systemized Orthodontic Treatment Mechanics. St. Louis, MO: Mosby; 2007. p. 285.  Back to cited text no. 2
    
3.
Freeman JE, Maskeroni AJ, Lorton L. Frequency of Bolton tooth-size discrepancies among orthodontic patients. Am J Orthod Dentofacial Orthop 1996;110:24-7.  Back to cited text no. 3
    
4.
Bernabé E, Major PW, Flores-Mir C. Tooth-width ratio discrepancies in a sample of peruvian adolescents. Am J Orthod Dentofacial Orthop 2004;125:361-5.  Back to cited text no. 4
    
5.
Endo T, Abe R, Kuroki H, Oka K, Shimooka S. Tooth size discrepancies among different malocclusions in a Japanese orthodontic population. Angle Orthod 2008;78:994-9.  Back to cited text no. 5
    
6.
Strujić M, Anić-Milosević S, Mestrović S, Slaj M. Tooth size discrepancy in orthodontic patients among different malocclusion groups. Eur J Orthod 2009;31:584-9.  Back to cited text no. 6
    
7.
Othman S, Harradine N. Tooth size discrepancies in an orthodontic population. Angle Orthod 2007;77:668-74.  Back to cited text no. 7
    
8.
Araujo E, Souki M. Bolton anterior tooth size discrepancies among different malocclusion groups. Angle Orthod 2003;73:307-13.  Back to cited text no. 8
    
9.
Smith SS, Buschang PH, Watanabe E. Interarch tooth size relationships of 3 populations: Does Bolton's analysis apply? Am J Orthod Dentofacial Orthop 2000;117:169-74.  Back to cited text no. 9
    
10.
Al-Dashti AA, Cook PA, Curzon ME. A comparative study on methods of measuring mesiodistal tooth diameters for interceptive orthodontic space analysis. Eur J Paediatr Dent 2005;6:97-104.  Back to cited text no. 10
    
11.
Bugaighis I, Karanth D, Borzabadi-Farahani A. Tooth size discrepancy in a Libyan population, a cross-sectional study in schoolchildren. J Clin Exp Dent 2015;7:e100-5.  Back to cited text no. 11
    
12.
Crosby DR, Alexander CG. The occurrence of tooth size discrepancies among different malocclusion groups. Am J Orthod Dentofacial Orthop 1989;95:457-61.  Back to cited text no. 12
    
13.
Uysal T, Sari Z. Intermaxillary tooth size discrepancy and mesiodistal crown dimensions for a Turkish population. Am J Orthod Dentofacial Orthop 2005;128:226-30.  Back to cited text no. 13
    
14.
Al-Khateeb SN, Abu Alhaija ES. Tooth size discrepancies and arch parameters among different malocclusions in a Jordanian sample. Angle Orthod 2006;76:459-65.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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