Abstract
It is generally known that the centric position was used to take bite registration and adjust occlusion. However, mandibular position is influenced not only by opening muscles and elevating muscles, but also by the muscles of facial expression. The purpose of this study was to examine the influence of the muscles of facial expression on centric position. The subjects were 3 normal adults using the Gnathohexagraph measuring system. They were required to track their angles of the mouth posteriorly from the centric position. The deviations of the condyler position were recorded. The results showed that the level of tension of the muscles of facial expression were responsible for posterior/upwards deviations of the mandibular position.
