THE DETERMINATION OF OPTIMAL HUMAN JAW MOVEMENTS BASED ON THEIR ASSOCIATION WITH CHEWING PERFORMANCE

Chewing performance is an expression of the functional capacity of the jaws and teeth. In a recent study of fully dentate subjects, the variation in chewing performance could not be explained by differences in occlusal contact area. It was now decided to investigate the possibility that chewing performance might be associated with certain patterns of jaw movement. Data from two previous studies using the same subjects were analysed using a step-wise regression to select variables of jaw movement that could predict chewing performance. A multivariate model with an R(2) value of 0.79 (p < 0.000) was generated with particle size as the dependent variable. Eight components of jaw movement made up the independent variables. Some of the more dominant variables in the model were those that describe a wide, bilateral chewing cycle with a predominantly lateral path of closure. Another powerful predictor of efficient chewing was a smooth, flowing movement with minimal changes in velocity. The inclusion of occlusal contact area in the model did not enhance its predictive capability. It was concluded that selected jaw-movement variables were significant determinations of chewing performance, and therefore could contribute to developing a baseline for normal masticatory function.