There is a need for further knowledge about the normal and abnormal growth patterns of bones and teeth. Genetic make-up, as well as various types of diseases and injuries such as trauma, inflammation, radiation and chemicals may affect skeletal and dental growth sites, thereby causing faulty growth. The degree of the subsequent deformity depends not only on the type, intensity, extent and chronology of the noxious agent, but also on the site and its particular involvement in growth activity. The knowledge of what happens to the stomatognathic system when some of its parts are altered is very important. Dentists are challenged to visualize the entire system in all its relationships: they must visualize the dynamics of how the system works. The relationship of the maxilla to the mandible and the mechanics of the stomatognathic system must be considered as a whole when considering the occlusion. The aim of this paper is to focus attention on the biologic basis of facial asymmetries and the functional reasons for their stabilization.