The Role of Maxillofacial Structure on Condylar Displacement in Maximum Intercuspation and Centric Relation

Abstract

Purpose. This study is aimed at evaluating the impact of the craniofacial structure and occlusal conditions on the position of the articular heads of the mandibular condyles in the maximum intercuspal position (MIP) and comparing the centric relation (CR) and MIP of the mandibular condyles prior to orthodontic treatment. Methods. The studied group consisted of 33 women and 15 men (median age of 17.75 years). Contact points of opposing teeth in the MIP were assessed by hand-held casts. Condylar displacement (CD) in three spatial planes on both sides was measured on models mounted in an articulator using a mandibular position indicator (MPI). Patients were divided into groups according to craniofacial structures (vertical and horizontal growth directions). The Mann-Whitney, Kruskal-Wallis, post hoc Dwass-Steel-Critchlow-Fligner, and Pearson’s${\chi }^2$independence tests as well as Spearman’s nonparametric correlations were used in the statistical analyses. Results. Within the limitations of this study, no statistically significant correlation of CD with certain cephalometric measurements from a lateral cephalometric radiograph (ANB, SN-ML, and SGo/NMe) was observed. Correlation, however, was found between condylar displacement in the transverse axis and the mandibular plane angle SN-ML ($p=0.033$) and also between condylar displacement in the anteroposterior axis and a midline shift of the mandible ($p=0.041$). The results revealed a relationship between Angle’s classification of molar position on the right side and anteroposterior CD values ($p=0.006$). Conclusions. Cephalometric measurements cannot be used to predict CD at the level of the condyles. Analysis of occlusal conditions of models mounted in an articulator is desirable for patients with Angle’s class I and lower jaw asymmetry.