Successful treatment of patients requiring complex dental restoration requires a comprehensive evaluation of their existing occlusion. Using a systematic and ordered sequence for relating this occlusion to a physiologic standard greatly facilitates the treatment planning process of reconstruction. Reconstructing the occlusion in this same orderly sequence then significantly enhances the control and predictability of the procedures performed by all practitioners involved in management of the case. Six closely inter-related elements of an occlusion must be evaluated and frequently modified in treatment. Part 1 of this article will discuss two elements of the occlusion, in the order of their evaluation - centric relation position of the mandible and vertical dimension of occlusion.