Alteration of the angle of the coronoid process in prognathism

Muscles and bones may dynamically affect the functions of each other, resul ting in changes in the activity of the muscle and/or morphological change i n the bones. However, alterations of the morphology of the coronoid process have not been documented in relation to the temporal muscle between the ma ndible and the cranium. Angles of the coronoid process to the line through the right and the left frontotemporale were measured on posteroanterior (PA ) cephalograms in patients with normal occlusions and Class II, division 1 malocclusions, and those with true skeletal Class III malocclusions. Standa rd deviation of the angle of the coronoid process in patients with Class II I malocclusions was greater than those subjects with normal occlusion or Cl ass II, division 1 maloclusions. Differences of angles between the right an d the left coronoid process in each patient of either sex were significantl y large in true skeletal Class III malocclusions (both P < 0.001). Large va riation of angle of the coronoid process was related to prognathism, and th is effect may represent adaptation of temporal muscle function to a variety of alterations in mandibular morphology.