Cephalometric evaluation of symmetric and asymmetric extraction treatment for patients with Class II subdivision malocclusions.

摘要

INTRODUCTION: The purpose of this study was to cephalometrically compare the dentoskeletal and soft-tissue changes consequent to orthodontic treatment in patients with Class II subdivision malocclusion treated with asymmetric and symmetric extractions. METHODS: The sample included 54 patients with Class II subdivision malocclusion and full complement of permanent teeth, including first molars, at the beginning of treatment. Patients in group 1 (n = 27) were treated with the asymmetric extraction of 3 premolars and had initial and final mean ages of 14.07 and 16.71 years. Patients in group 2 (n = 27) were treated with the symmetric extraction of 4 premolars and had initial and final mean ages of 13.35 and 15.75 years. Lateral cephalometric radiographs were taken at pretreatment and posttreatment. T tests were used to compare the groups at pretreatment and the treatment changes between groups. RESULTS: The results demonstrated that the asymmetric extraction group had significantly less mandibular incisorretraction, less soft-tissue retraction, and greater increases in mandibular incisor extrusion and mandibular molar asymmetry index than the symmetric extraction group. CONCLUSIONS: It was concluded that the 3-premolar asymmetric extraction protocol in Class II subdivision malocclusions produces significantly less mandibular incisor and soft-tissue retraction than the 4-premolar extraction protocol.