Influence of Changing the Location of Anterior Guidance Teeth on the Condyles during Unilateral Clenching.

Abstract

This study was conducted to examine the influence of changing the location of guidance teeth on the movements of the condyles during simulated parafunctional unilateral clenching. Two healthy adults volunteered for this study. To simulate bruxist behaviour, they were asked to perform maximal clenching in a lateral edge to edge position with onlay-like metal guidances that increased by 10 degrees the inclination of the lateral excursions, but did not change at all the vertical dimension in intercuspal position. A 6-degree-of-freedom jaw movement measurement system was used to record 3-dimensionally the condylar movements. When the contact point of the anterior guidance was moved posteriorly along the arch from canine to second molar, the trajectory of working condyle movement was an antero-superior one up to the first premolar; but from the first molar this trajectory changed dramatically to an inferior one during unilateral clenching. All the trajectories of nonworking condyle movement were superior during unilateral clenching. In consideration of the movements of the working condyle during eccentric movement in a parafunctional environment, the results suggested that the location of guidance teeth should be relegated to the anterior region of the working side.