Abstract
Tooth guidance was studied in 5,146 Japanese subjects, aged 10 to over 60 years, with complete dentitions. Casts mounted on an SAM articulator with face bow-transfer offered the possibility to measure the guidance inclination on both sides of the dentitions. The functional points F1 and F2,which represent the starting point and end point of the tooth guidance, were recorded by a 3D digitizer on maxillary teeth from central incisor to second molar. The inclination of the line connecting F1 to F2 with reference to the axis orbital plane was calculated for each tooth. The inclination of the occlusal plane connecting the F1 points of all teeth from central incisor to first molar, central incisor to first premolar, and second premolar to second molar was also calculated. The values were compared in different age groups and different occlusion groups; Angle Class Ⅰ,Ⅱ, and Ⅲrelationships. The average occlusal guidance sequentially decreased from anterior to posterior. Occlusal guidance indicated that inclinations of canine and first premolar gradually decreased with age, while those of molars were increased. The occlusal plane measurements showed that although the anterior occlusal plane was relatively stable with age, the posterior occlusal plane continuously and gradually flattened. The results confirmed the concept of sequential guidance with canine dominance, although the inclinations of guidance between neighboring teeth decreased with age.
