Effect of occlusal interference on condylar position and trajectory of movement: a randomized crossover-controlled trial.

OBJECTIVE: The occlusal interferences may alter the position of the condyles in the articular fossa and trigger abnormal mandibular movements, but the specific effects on condylar position and movement trajectory are currently unknown. The present study was designed as a randomized crossover-controlled trial to investigate the direct effects of distinguished types of occlusal interference on condylar position and movement trajectory. METHODS: 14 volunteers with healthy dentition were recruited. Each of them underwent four occlusal interference conditions: mediotrusive occlusal interference (MOI), laterotrusive occlusal interference (LOI), dummy occlusal interference (DOI), and free of interference. The sequence of interferences was randomized. Mandibular movements were recorded and measured by using jaw motion analysis system, during which the condylar trajectory and functional parameters, including sagittal condylar inclination (SCI) and Bennett Angle (BA) were analyzed to assess the condylar motion status. Furthermore, a descriptive analysis of condylar positional trends was conducted to measure the relative three-dimensional position of the condyle. RESULTS: Affected by MOI, the condylar axis turned towards the anterior and superior directions. BA values exhibited a significant increase on the interference side and a decrease on the other side, accompanied by a reduction in SCI on the interference side. LOI caused a larger mandibular deviation angle towards the interference side, resulting in a notable increase in BA. The differences were all statistically significant (P<0.05). CONCLUSION: Occlusal interferences can alter the condylar position and movement trajectory during the mandibular movement in laterotrusion and protrusion. Different occlusal interferences have different influences, manifested in the varying values of condylar guidance inclination. TRIAL REGISTRATION: The study was registered at the Chinese Clinical Trial Registry on 01/05/2024 (Identification number: ChiCTR2400084150).