A study on the anterior tooth size discrepancies among orthodontic patients with varying malocclusions

Kim, Hyeok Soo; Shim, Hae Young; Nahm, Dong Seok

Abstract

Bolton analysis is widely used to predict tooth size discrepancy, but its accuracy has been challenged. The purpose of this study was to describe true anterior tooth size discrepancies among orthodontic patients and to evaluate the factors that affect true anterior tooth size discrepancies. The subjects consisted of 80 patients with varying malocclusions (Class I, Class II, Class III, and Class III surgery) who were treated orthodontically. Pre-treatment models, set-up models from post-treatment models, and lateral cephalometric radiographs were analyzed. The results were as follows. The means, the standard deviations, and ranges of anterior Bolton ratio in the present study were somewhat higher than those of Bolton's samples and Korean normal samples. The number of patients showing maxillary deficiency was larger than that of patients showing maxillary excess in view of true anterior discrepancies. There was a significant difference between anterior Bolton discrepancy from pre-treatment models and true anterior discrepancy from set-up models (p < 0.05). There was no significant difference in true anterior discrepancies among malocclusion groups (p > 0.05). And there was also no significant difference between the male and female groups (p > 0.05). Overbite and the incisal edge thickness of maxillary anterior teeth have little relationship with true anterior discrepancies. Multiple regression analysis showed that true anterior discrepancy was mainly determined by anterior Bolton ratio, upper incisor to occlusal plane angle after treatment, interincisal angle after treatment, and upper right lateral incisor width.