[Relationship between condylar displacement during clenching and condylar guide inclination].

Purpose: Many studies have reported the relationship between facial morphology and stomatognathic functions. The steepness of the articular eminence is an important morphological factor to determine the mandibular movement or mandibular positioning. The present study analyzed the relationship between the condylar displacement during clenching and the condylar guide inclination related to simulated loss of posterior occlusal support.

Methods: Nineteen clinical residents (4 females and 15 males, 24-31 years old) with healthy natural dentitions were recruited as subjects. To change the posterior occlusal support, occlusal splints fitted to maxillary dental arches were cut in sequence from the posterior toward the anterior side. The condylar displacements during maximum voluntary clenching under every occlusal condition were measured using a mandibular movement analyzing system with six-degrees of freedom. The sagittal condylar guide inclination was also measured using the same apparatus.

Results: 1. A greater loss of posterior occlusal support was associated with increased displacement distance of both condyles, however these values varied with the subject. 2. A significant positive correlation was observed between the displacement distance without splint and the relative displacement distance with splint (difference between before and after loss of occlusal supports). 3. A significant negative correlation was observed between the displacement distance without splint and the sagittal condylar guide inclination, and was also observed between the relative displacement distance with splint (above-mentioned) and the sagittal condylar guide inclination.

Conclusion: These results suggest that the sagittal condylar guide inclination is an important factor in condylar displacement during clenching.