Evaluation of Bolton Anterior and Overall Tooth Size Discrepancy among Different Malocclusion Groups in Southern Indian Population: A Retrospective Study

Introduction: Orthodontic treatment involves distinct phases, each with unique traits and challenges. In particular, the “Finishing” stage is renowned for the fine corrections needed to achieve optimal results. Discrepancies in tooth size contribute significantly to the difficulties encountered during this stage. Aim: To assess differences in maxillary and mandibular tooth size discrepancies among different sagittal malocclusion groups in a South Indian population using the derived Bolton formula. Materials and Methods: A retrospective study was conducted in the Department of Orthodontics at Karpaga Vinayaga Institute of Dental Sciences, Kanchipuram, Tamil Nadu, India, over three months, from July to September 2024. A total of 120 high-quality pretreatment orthodontic study models were selected. The inclusion criteria comprised patients aged 16 to 25 years with full permanent dentition up to the first molars in both arches. The models were categorised into three groups based on Angle’s classification of anteroposterior malocclusion: Class I (n=40), Class II (n=40), and Class III (n=40). The mesiodistal width of each tooth up to the first molar on both sides was measured at the interproximal contact points using a digital caliper. Bolton’s anterior and overall ratios were calculated using the measured values. Statistical analysis included one-way ANOVA to evaluate differences in mean Bolton ratios across groups, and the Chisquare test to assess the distribution of anterior and overall Bolton discrepancies among the malocclusion types. A p-value of <0.05 was considered statistically significant. Results: The prevalence rate of tooth material discrepancies in the anterior region for Angle Class I and Class III groups was significantly greater than that for Class II groups. The mean overall and anterior ratios were not significantly different between the malocclusion groups (p=0.13 and p=0.72, respectively). Conclusion: The present study indicated that Class I and Class III show an increased frequency of tooth material discrepancies compared with Class II.