Dominance of facial components in predicting treatment outcome of Class II, division 1 malocclusion

Abstract

Introduction Treatment outcome of Class II, division 1 (Class II-1) malocclusion associated with retrognathic mandible depends on several constitutional components rather than a prominent change in one of them. In a prior study, the cant of the anterior contour of the symphysis along with the ANB angle were shown to be good predictors of forward chin projection following Class II-1 orthopedic treatment started in prepubertal children. Aims 1. Evaluate Class II treatment effect on the various facial components among growing and adult age groups, and between malocclusion severity subgroups; 2. Develop predictive models of treatment response (favorable vs unfavorable) based on objective cephalometric classifications and on the judgments of a panel of experts; 3. Explore the correspondence between the panel assessment of improvement of treated Class II-1 patients and different cephalometric outcome predictors. Design The research comprised 2 main parts; a cephalometric evaluation of the major facial components including variations in age groupings (growing and adult) and severity of malocclusion, and a panel assessment of the soft tissue facial profile in conjunction with the nature of treatment outcome. Methods A total of 179 patients recruited under strict inclusion criteria of Class II-1, and treated in the Division of Orthodontics and Dentofacial Orthopedics at AUBMC, were classified into 2 age groups (growing and adults) based on superimposition of T1 and T2 lateral cephalograms. The growing group was further divided into pre-pubertal and post-pubertal subjects based on the time of initiation of treatment (T1). Each age group was also stratified based on the ANB angle into severity categories (high: ANB between 4.50 and 6.5o; low: ANB 6.6o) of the malocclusion. All patients must have reached Class I occlusion at the end of treatment (T2). Linear and angular measurements gauging relations among cranial base and both jaws were taken on pre- and post-treatment lateral cephalograms. Treatment responses were