In the stomatognathic system teeth with supportive tissues, masticatory muscles (m.masseter, m.temporalis, m.pterygoideus medialis et lateralis) and temporomandibular joint act together as a unit participating in opening and closing mouth movements and movements of the mandibule ahead, back and on the side. Mastication is a complex process of grinding and preparing the food for swallowing and digestion. It coinsists of series of mandibule movements and it depends on teeth condition, food consistency, chewing force, chewing movements and tempo. The teeth take active part in the process of food grinding and so the abrasion appears as a consequence. We differ horizontal and vertical abrasion that changes occlusal surfaces and incisal margins of teeth. The cusps are reduced and the ad palatum abrasion appears on molars. Demastication abrasion is not distinct among modern humans because we eat prepared and soft food, while Eskimos, some African tribes and primitive man according to findings of skulls have extreme abrasion as an effect of consumption of tough food that contains abrasive substances. The increase of food consistency causes the increase of the size of masticatory motions and the increase of masticatory muscles activity, more chewing movements and teeth contacts.