Autocclusal mechanisms in the carnivore dentition.

Abstract

Occlusal events in the mammalian dentition occur too rapidly to be controlled by neuromuscular coordination alone. Another mechanism must be postulated to account for the paradox of extraordinarily precise but rapid occlusal events. Autocclusal mechanisms are those controlled by the dentition, as opposed to neuromuscular systems. The first autocclusal event in carnivore jaw mechanics occurs when the upper and lower canines come into contact. Although canines have many functions, their primary role in carnivores is to serve as occlusal guides for the postcanine teeth. The masticatory muscles then position the carnassials, and fibrous food engages a catchment mechanism between the upper and lower carnassials to keep them in tight apposition. The existence of autocclusal mechanisms allows a shift from dP3/dP4 to P4/M1 shear to occur readily in ontogeny because the masticatory neuromuscular system "learns" how to chew by using teeth that are currently in position in the jaw.