Bolton anterior tooth size discrepancies among different malocclusion groups

Orthodontic treatment comprises different phases with unique characteristics and challenges. The orthodontic "finishing" phase is recognized for the multitude of details necessary to achieve an excellent result. In some cases, the finishing phase is very difficult, requiring the production of complicated biomechanical forces to reach a satisfactory orthodontic solution. A high percentage of these finishing-phase difficulties arise because of tooth size imbalances that could have been detected and considered during initial diagnosis and treatment planning. The present study aimed to investigate the correlation between anterior tooth size discrepancies and Angle's Class I, II, and III malocclusions, as well as their prevalence in the Brazilian population from Belo Horizonte. We assessed the mesiodistal width of six anterior teeth in 300 patients, who were selected randomly. These patients were allocated to three groups according to their malocclusion. A chi-square test was performed to statistically compare the prevalence of anterior tooth size discrepancies among the three malocclusion groups and two genders. Analysis of variance was used to compare the mean Bolton anterior tooth size ratios as a function of Angle classification and gender. Statistical differences were determined at the 95% confidence level (P < .05). The important conclusions of our study are as follows: (1) Individuals with Angle Class I and Class III malocclusions show significantly greater prevalence of tooth size discrepancies than do individuals with Class II malocclusions; and (2) Mean anterior tooth size discrepancy for Angle Class III subjects was significantly greater than for Class I and Class II subjects.