Evaluation of Bolton's Ratio in Normal Occlusion and Different Types of Malocclusion in Iranian Population

Abstract

Background: The Bolton analysis is commonly used by orthodontists. The Bolton ratios of different populations are significantly different from the standard values of Bolton. This study sought to examine the Bolton's anterior and overall ratios in various malocclusion types in Mashhad, Iran, in contrast to the Bolton’s standards. Methods: This descriptive-analytical study was conducted on 240 study models of patients (121 males and 119 females) in four groups (n= 60 cases) of normal occlusion, Class I, Class II, and Class III. The mesiodistal dimensions of the teeth were measured twice using a digital caliper. The anterior and overall ratios of Bolton were calculated. Statistical analysis was conducted utilizing SPSS 18.0. Results: The mesiodistal width of the maxillary lateral incisors in normal occlusion cases was greater than that in Class I, Class II, and Class III malocclusions (P<0.05). Conversely, the mesiodistal width of the maxillary first and second premolars was the greatest in Class II and the smallest in Class III malocclusion (P<0.05). Correlation was not observed between dental ratios (anterior and overall) and gender or malocclusion groups (P>0.05). Furthermore, the anterior ratio was significantly higher than the Bolton's standard in Class I and III malocclusion groups (P<0.05). The normal occlusion group's overall ratio was significantly lower than the Bolton's original ratio (P<0.05). Conclusion: Implementing the Bolton analysis in the population of Mashhad, Iran should be approached with caution.