Evolution of occlusion and occlusal instruments.

All occlusal concepts are based, in part, on theory, and all theories may have borrowed from the past. This article reviews the evolution of occlusal concepts to understand how differing theories interrelate, where they agree, and where each concept contributed to the ongoing understanding and evolution of occlusion principles. Also, the flexible and practical concept of biologic occlusion is presented. The philosophy of biologic occlusion is one that functions in health. The goals of biologic occlusion are also presented.