Bilateral asymmetry in the tooth relationships of orthodontic patients

Abstract

Objective: To quantify the nature and extent of bilateral dentoalveolar asymmetries in routine adolescent orthodontic patients. Materials and Methods: Eight left-right pairs of occlusal dimensions were measured from dental casts (n = 211 subjects) with proportionate samples of class I, II, and III malocclusions. Results: Directional asymmetry is a subtle, but pervasive feature of the dental arches, with systematically larger dimensions on the left side. Prior studies attribute this sidedness to compensations for hemispheric laterality. Patient's sex did not influence the magnitude of asymmetry, but patients with class II malocclusion exhibited significantly greater asymmetries, particularly in the anterior segment. Inspection suggests that this is attributable to the lack of coupling and guidance of the teeth between the jaws. There is a significant association between the severity of class II buccal-segment relationship and the extent of left-right asymmetries. Conclusion: Clinically, these lateralities need to be anticipated, particularly in class II malocclusions, and incorporated into the treatment plan. © 2007 by The EH Angle Education and Research Foundation, Inc.