LOCATION OF THE MANDIBULAR CENTER OF AUTOROTATION IN MAXILLARY IMPACTION SURGERY

Controversy exists about the location of the center of autorotation of the mandible after maxillary impaction surgery. This investigation fo cuses on the problems associated with locating that center of autorota tion and identifies factors that can increase the probability of accur ately identifying its location for predicting surgical outcomes. The r eliability of the Rouleaux technique for calculating the centers of ro tation is established and is shown to be acceptable, as long as the la ndmarks used for determining the center are properly selected, and the magnitude of the rotation required is sufficient. The location of the centers of autorotation of the mandibles after maxillary impaction su rgery for 46 patients was used to investigate the errors associated wi th landmark selection and amounts of rotation. Although there is much variation in its location, the center does not lie within the body of the condyle but instead lies away from the condyle. Guidelines for max imizing the reliability of predicting surgical outcomes on the basis o f autorotation of the mandible after maxillary impaction surgery are g iven.