A clinical study of condylar position of three biotypological facial groups.

Abstract

Objectives: Orthodontic diagnosis and treatment related to the orthopaedic position of centric relation (CR) requires a comprehensive study of the condylar position (Roth, 1981; Cordray, 2006). According to the craniofacial architecture, the hyperdivergent facial type seems to be more prone to condyle displacement than other facial groups. Therefore, it was put into hypothesis that it is on the hyperdivergent type that the centric slide (CS) is more frequent and wider. This work intended to investigate and compare CS on an hyperdivergent, an hypodivergent and an intermediate group. Materials and methods:The displacement from CR to centric occlusion (CO) namely CS was assessed on the vertical (ΔZ) and sagittal (ΔX) plans with a mandible position indicator MPI® on mounted models in a semi-adjustable articulator SAM® 2P. The cases were selected from a sample of 742 orthodontic patients submitted to sequential criteria that allowed coming to an asymptomatic orthodontic population that surpassed growth peak and were divided in three groups of 36 elements each according to cephalometric criteria (Girardot, 2001). The groups were studied and then compared statistically using t Student test with a 0.05 level of significance.Results:The results demonstrated that CS is more common and generally wider on the hyperdivergent group, being likely to occur in rear-bottom direction on hyperdivergent and intermediate groups and front-bottom on the hypodivergent. In any of the groups it was possible to verify that vertical displacement was wider than sagittal, being the vertical displacement significantly higher (table 1) on the hyperdivergent (p = 0,003).Conclusions:Although the condyle displacement is more frequent on the hyperdivergent, this study reinforces the need of mounting the models on articulator in CR and performing the evaluation of the condyle position as protocol in the study of any orthodontic case. These procedures supply relevant and mandatory information on the orthodontic decision.