Phenotypic characterization of Class II malocclusion

Background: Genes predispose to disproportionate growth of the human face resulting in unbalanced maxillo-mandibular relationships and severe malocclusion. The success of genetic studies aimed at identifying causative genes for complex traits such as malocclusion depends greatly on a well-characterized phenotype to reduce heterogeneity. Purpose: The purpose of this study is to characterize the skeletal and dental variation present in Class II malocclusion into distinct homogenous phenotypic groups to help empower future genetic studies aimed at identifying the etiology of malocclusion. Research Design: Cephalometric radiographic landmarks and statistical data reduction methods will be used to find the most common phenotypic groupings in a sample of 309 Caucasian Class II adults. Results: A principle component analysis produced 7 principle components that explained 81% of the variation and a subsequent cluster analysis identified 5 distinct clusters of Class II patients.