Influence of oral characteristics and food products on masticatory function.

Mastication is a complex process that involves activities of the facial muscles, the elevator and suprahyoidal muscles, and the tongue. These activities result in patterns of rhythmic mandibular movements, food manipulation, and the crushing of food between the teeth. Saliva facilitates mastication by moistening food particles, making a bolus, and assisting swallowing, whereas food consistency modifies masticatory forces, the mandibular jaw movements, the duration of the mastication cycle, and the number of cycles preceding the first swallow. Jaw elevator EMG activity research shows a clear relation between muscular activity and food properties. The teeth, masticatory muscles, and temporomandibular joints are also important because together they form the mechanism by which the food particles are fragmented. Hard and dry foods require more chewing cycles and a longer time in the mouth until swallowing for sufficient breakdown to take place and for enough saliva to be added to form a coherent bolus safe enough for swallowing. Product characteristics, the amount of saliva, dentition, and bite force affect the chewing performance. This study presents an update and synopsis of the effects of saliva, food, dentition, muscle force, and temporomandibular disorders on the masticatory process.