The instantaneous transverse changes in the maxilla due to different points of force application.

The effects of different sites of an expansile force on the maxillae of three monkeys were studied. A lateral force of five pounds was delivered directly to four locations on each maxilla. Aluminum rods, rigidly attached to the teeth of each buccal segment, were photographed before and after each force application. The data indicated that the pattern of lateral maxillary displacement is related to the position of the lateral force in relation to the center of resistance of each maxilla.