Evaluating condylar head morphology as it relates to the skeletal vertical facial dimension: A three-dimensional semi-automated landmark study

Abstract

Introduction: Condylar growth direction and rotation affect the occlusion, especially in the vertical dimension. The first objective of this study was to evaluate the reliability of a novel three-dimensional semi-automated landmark computer software on mapping the head of the mandibular condyle using cone-beam computed tomography (CBCT). The second objective was to evaluate qualitatively how condylar morphology differs three-dimensionally according to skeletal vertical pattern and mandibular morphology in healthy adults using CBCT. Materials and Methods: A total of 242 (169 females and 73 males) participants were eligible for the study. Participants were selected at random from the 242 to create three groups of 10 participants based on their MP-SN° and assigned to a brachyfacial group, dolichofacial group, and mesofacial group. The thirty participants were also divided by mandibular symphyseal morphology according to the chin angle (Id-Pg-MP°). Each subject’s condyles were landmarked using Stratovan’s Checkpoint software. A Procrustes analysis was then used to generate an average condylar shape for each of the six groups from which to evaluate shape differences. Results: Checkpoint proved to be a reliable method of placing landmarks on the condyle with a low coefficient of variation of 1.81% (standard deviation/mean). Qualitative analysis of the Procrustes averages revealed brachyfacial average showed a moderate anterior lean from the sagittal, anterior convexity from the axial, and medial lean from the coronal views. The dolichofacial average showed a mild anterior lean from the sagittal, anterior concavity from the axial, and a symmetrical half-dome shape from the coronal. The obtuse chin angle group average displayed morphology similar to the brachyfacial average, whereas the acute chin angle group average displayed morphology similar to the dolichofacial average. Conclusions: Checkpoint is reliable software to landmark the temporomandibular joint. There are differences in average morphologies between all groups.