Bolton discrepancy in an Iranian population and its relation with maxillary lateral incisors’ size

Abstract

BackgroundBolton’s two main ratios describing the proportional size of upper and lower teeth, could contribute to estimating the excess or deficiency of tooth size necessary to obtain an ideal occlusion. However, the mean Bolton values are not the same among different societies. Determining the prevalence of tooth size deviations from population-specific Bolton indices might help local orthodontists to have a more concise treatment plan.ObjectiveThe study aimed to define the prevalence of clinically significant tooth size discrepancies (TSD) in an Iranian population and to evaluate the influence of lateral incisors’ size on this discrepancy.MethodsThis cross-sectional study was conducted on study casts of orthodontic patients attending Imam Reza Dental Clinic from September 2008 to December 2016. The sample comprised of 150 randomly selected pre-treatment study casts (64 males and 86 females from 17 to 28). The mesiodistal diameter of all permanent teeth from the first molar on the right to the first molar on the left was measured using 2 similar digital calipers, and Bolton analysis was calculated. Subjective visual estimation of Bolton discrepancy was also performed. SPSS v18.0, Wilcoxon signed ranks test, Pearson correlation and Receiver Operating Characteristic (ROC) curve analysis were used for statistical analysis. A p<0.05 was considered statistically significant.ResultsIn the sample group, 34.7% had anterior Bolton index (ABI) and 20.7% had total Bolton index (TBI) greater than 2 Standard Deviations (2SDs) of Bolton’s means, and about half of them required correction of the ABI considering the actual size of discrepancies (mm). The sensitivity of estimating clinically significant tooth size discrepancy more than 2SDs of Bolton’s ABI and the visual judgment was 96.0% and a cut-off point of −0.12mm was obtained.ConclusionBolton’s analysis should be routinely performed in all orthodontic patients, and visual estimation of TSD would be suggested as a screening method in the first visit prior to measurements and set-ups.

The tooth size discrepancy among orthodontic patients and normal occlusion individuals from Saudi Arabia: A three-dimensional scan analysis of diagnostic casts

“…The ± 2SD of BM found in the current study (25%) is alike reported for other populations of the world [ Table 2 ]. [ 9 10 13 17 23 31 32 35 ] A considerable number of normal occlusion subjects (20%) in the current study had AR deviated more than ± 2SD of BM, which is significantly larger than studies on other populations [ Table 2 ]. This finding could signify the influence of ethnicity on the tooth and jaw size of an individual.…”

“…[ 14 ] Some studies on other ethnic groups were in concordance with Bolton's ratios,[ 11 15 16 ] while others are not. [ 17 18 ] Bolton's study was based on ideal occlusion and may not accurately contemplate the discrepancies in malocclusion cases. Some of the studies on malocclusion groups were in concordance with Bolton's ratios,[ 9 19 ] while others are not.…”

“…[ 27 ] Similarly, Irani orthodontic patients had a discrepancy (±2SD) in AR of 34.7% and OR of 20.7%. [ 17 ] Aldrees et al . reported that orthodontic patients from Central Saudi Arabia had a discrepancy (±2SD) in AR of 17.4% and OR of 10.4%.…”

A simple method for quick evaluation of the anterior tooth ratio: an observational study

“…Likewise, Smith [17] also found that the overall ratio of the African Americans was larger than that of Caucasians, and this was attributed to the difference in the size of the posterior teeth. Significant differences were also seen in the anterior ratio or overall ratio compared with Bolton's original ratios among certain populations, including those from India [18], Turkey [16], Iran [19], and Saudi Arabia [42]. As early as 1991, the Chinese have established their own standard value of the Bolton ratio [43], and since then, many have studied and established standard values in different regions of China.…”

“…The Bolton analysis is now commonly used by clinicians as an objective method for the precise measurement of tooth proportion to guide clinical diagnosis and treatment. This has been studied across different ethnicities and regions [15][16][17][18][19], among various types of malocclusion [20][21][22][23][24], and in the presence of new indicators [25]. These studies did improve the accuracy and applicability of the Bolton analysis.…”