The posture of the mandible is determined by the relationship of condylar growth to vertical molar growth. These causative growth increments functioning against one another cause the mandible to move forward, as well as to cause it to tip forward and backward. All downward movements of the chin are caused by vertical molar growth increments. The Posture of the Mandible
The mandible automatically follows the positions of the teeth laterally to improve the efficiency of mastication, but must have help to follow the teeth forward. This help may come from growth processes or it may come from man's efforts. When growth has ceased, the forward movement of the mandible seems to be yet possible by the forward movement of the fossa and the bending of the neck of the condyle. Pancherz and his coworkers have shown that there is adjustability in fossa and De Vincenzo has shown that there is adjustability in the neck of the condyle.
These movements of the mandible are the most important and most basic of all biological principles involved in the study of the treatment of malocclusion. It is imperative that they be taught to the graduate student early in his or her training. It is the foundation of all learning in the orthodontic profession.
Bibliography 1. Pancherz, Hans, D.D.S., Ruf, Sabine, D.D.S. and Kohlhas, Peter, D.D.S., The Effective Condylar Growth and Chin Position Changes in Herbst Treatment. A Cephalometric Roentgenographic Long-Term Study. AJODO, Oct. 1998, 114, 437-46.
2. De Vincenzo, J. P., Changes in Mandibular Length, before, during and after Orthopedic Correction of Class II Correction of Malocclusion, using a Functional Appliance. Am. Journal of Orthod., 1991; 1999: 241-57.
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