Craniofacial adaptations after total maxillary osteotomy in Macaca irus: a cephalometric and histologic study.

Five Macaca irus monkeys were used in this study to determine cephalometric and histologic changes after total maxillary impactions. In the three experimental animals, the maxilla was impacted 5 to 7 mm. and lateral cephalograms were taken over a 150-day period. By superimposing on craniofacial implants, osseous and dental changes were measured. Excellent skeletal stability was demonstrated during the postoperative period. Histologically, there was normal osseous healing of the osteotomized maxillas. Accompanying the counterclockwise rotation (overclosure) of the mandible, there was extensive change in the temporomandibular joint. In the experimental monkeys, the fibrous articular covering of the temporal fossa was thin and irregular. The condylar cartilage appeared atrophic and showed considerable aging; also, the articular disc was much thicker in the experimental animals. The study showed the superiorly repositioned total maxillary osteotomy to be a stable procedure after 150 days of postoperative observation. However, further studies are needed to investigate the neuromuscular and adaptive response of temporomandibular articulation and mandibular rest position after maxillary surgical procedures.