Overbite Correction and Smile Esthetics

Overbite correction is an essential component of successful orthodontic treatment. Authors claim that the method used to reduce OB may negatively affect smile esthetics. Objectives: The purpose of this study was to determine differences in treatment outcome between two common OB reduction methods. Methods: This prospective clinical trial involved 40 patients with deep OB treated using a maxillary intrusion arch (IA) or bite plate (BP). A clinical exam, photographs, and a lateral cephalometric radiograph were collected and compared between groups at the start, after OB correction, and at treatment completion. Results: 18 IA and 14 BP patients completed treatment. OB correction was successful in both groups but faster in the BP group (5.3 vs 3.7 months; P<0.05). IA patients showed significantly more maxillary incisor intrusion (1.2 vs 0.2 mm; P=0.003) and reduction of anterior tooth display (2.1 vs 0.8 mm; P<0.001) and both groups showed a tendency for flattening of the smile arc at the end of OB correction (47% and 69%; P>0.05). By the end of treatment, there was no difference in overall treatment time (28.8 vs 25.2 months; P>0.05), amount of incisor intrusion (0.6 vs 0.1 mm; P=0.32) or anterior tooth display change (2.0 vs 1.4 mm; P=0.28). Smile arc consonance improved from post-OB correction flatness in both groups with 29% of IA patients and 38% of BP patients experiencing flattening by the end of treatment, consistent with levels previously reported for orthodontic treatment in general. Conclusion: Intrusion arches and bite plates achieve overbite correction successfully but differently, resulting in differences in OB correction speed, differences in tooth positioning, and changes in esthetics. However, the differences are not significant by the end of orthodontic treatment. (This study was supported by the Southern Association of Orthodontists, the VCU Alexander Fellowship Fund, and the MCV Orthodontic Education and Research Foundation)