The masticatory system--an overview.

Masticatory muscle physiology has been evaluated mostly from electromyographic recordings. However, electromyography coupled with jaw-tracking devices has provided much more information of the correlation between jaw movements and muscle activity. Knowledge of how the mandible moves during mastication has greatly influenced procedures in clinical dentistry. The aim of this overview is to give basic description of the classical studies of the physiology, function and neural control principles of the mastication. Mastication is the action of breaking down of food, preparatory to deglutition. This breaking-down action is highly organized complex of neuromuscular and digestive activities. The duration and forces developed in the power stroke vary within and between individuals and for the type of the food being chewed. It has been suggested that the observation of masticatory movements may be of diagnostic value for assessing disorders of the stomatognathic system, but there is not clear evidence to show significant differences. The action of masticatory muscles during chewing varies between subjects in amplitude, onset timing, and duration of the chewing cycle. Since tooth guidance has an enormous influence on muscle activity during chewing and swallowing, it is advisable to make restorations compatible with the functional movement patterns of the patient rather than expect the patterns of the mastication to adapt to the new made restorations.