Musculoskeletal adaption to surgical advancement of the mandible.

This study was carried out in order to evaluate musculoskeletal adaption to surgical advancement of the deficient mandible. 10 adult individuals with mandibular deficiency were studied before and 3 months after surgical advancement of the mandible via lateral cephalometric radiography, kinesiometry, and electromyographic instrumentation. 10 adult controls were studied at the same intervals, but underwent no surgery. The data was entered into a DEC System-10 computer for morphometric comparison and statistical analysis. The results of this investigation demonstrate that musculoskeletal adaptions occur within the stomatognathic system following surgical advancement of the mandible. 3 months following surgery, the clinical and physiological rest positions of the mandible as well as the masticatory electromyographic activity were unchanged in both the control and the surgery groups. The rapid, functional adaptions that occurred in the surgery group are apparently due to changes in posterior ramus-mandibular body relations and neuromuscular adaption within the masticatory and suprahyoid musculature.