Edentulous position of the temporomandibular joint.

Two bilateral Schuller's position radiographs were made of 10 edentulous patients with complete dentures. In one radiograph, the complete dentures were in place in centric occlusion. For the other radiograph, the complete dentures were removed and the maxillary and mandibular residual ridges approximated as closely as possible. This position is referred to as the edentulous position of the temporomandibular joint (TMJ). Findings indicate that in the edentulous position the average size of the upper and posterior TMJ spaces and the distance from the center of the condyle to the center of the glenoid fossa on the Y axis of the TMJ are smaller than measurements in the intercuspal position. The size of the anterior space and the distance between the two centers on the X axis are larger in the endentulous position. Because vertical dimension is reduced in the endentulous position, the mentum is in a superior and protrusive position. The study indicates that when the maxillary and mandibular residual ridges are approximate there is a pathologic position of the TMJ and the mandible caused by the loss of all teeth. The study shows that the condyle has the potential to move backward and upward excessively. As a result of the study, the concept of the edentulous position of TMJ is introduced. This concept is important in determining the proper position of the condyle in the glenoid fossa and the correct vertical and horizontal jaw relationship of an edentulous patient when complete dentures are made.