E very mandibular movement is the result of the following physiologic factors: (1) action of the masticatory muscles, (2) nature of the internal components of the temporomandibular joint, (3) morphology of the dental occlusal surfaces, and (4) anatomy of the osseous articular pieces of the joints. During lateral movement, these factors act to produce a smooth displacement of the mandible. This physiologic concept is difficult to relate to clinical reality and permits different points of view regarding occlusal relationships in lateral movement. Griffin and Malor’ stated that the occlusal morphology of the working side teeth is fundamental for mandibular guidance, the canines assuming the greater part of this role. Gibbs and Lundeer? stated that the working side occlusal contacts guide the mandible at the end of the masticatory cycle. Lee3 noted that the influence of the canines palatal anatomy on the condylar pathway in lateral movement cannot be verified. Unlike the previous workers, Guichet4 observed during pantographic recordings that lateral guidance is essentially the result of many characteristics of the joints, including the morphology of osseous pieces. Mongini,5 in comparing pantographic recordings and joint tomography, showed that correspondence exists between condylar shape and the outline of the lateral movements. Finally, Ramfjord and Ash6 stated that correspondence exists between the medial slope of the glenoid cavity, the occlusal morphology, and the lateral movements. This literature review, indicates that no agreement exists about the relative value of the physiologic factors and that the two main factors are the working side occlusal morphology, especially the maxillary canine slope, and the articular morphology. Other studies considered another factor, the universal modifier of occlusal and articular morphology, dental attrition. Although Demirjian’ found no correlation between articular morphology and dental wear, some studies since 1970 report correlations. These later