A Study Regarding with Principles of Occlusion in Japanese

Occlusal morphology is considered to be consistent with mandibular movement and part of Nature's schematic way of organizing part that may coexist while carrying out their intended functional requirements. The plane of occlusion, the inclination and length of guiding planes and the horizontal and vertical overlap of teeth are fundamental factors which also must coexist and be organized with mandibular movement. The main points in this investigation were providing the functional parameters of occlusion in Japanese subjects. Laterotrusive guiding planes increased in steepness from the second molar to the canine. This provides a continuous disocclusion in laterotrusion until canine alone assumes this function as described by Slavicek. The position for the lower incisal edge was located at the end of the steep guiding plane (F3) or shortly posterior. Intercoronal angle, space between labial surface of the lower incisors and the lingual concavity of the upper incisors, is functional freedom which measured as approximately 47 degree in this study. Measurements in difference between inclination of guiding plane of the upper incisors and the functional parameter of the temporomandibular joint indicated that the incisal guidance (S) should be 9.8 degree steeper than the horizontal condylar inclination (HCI) . Occlusal plane constructed by the sequence of upper passive centrics inclined 10 to 11 degree to the axis-orbital reference plane (AOP) . From these findings, it was indicated that natural normal occlusion have a certain rules and basic forms described as sequential functional guidance occlusion by Slavicek.