SURGICALLY ASSISTED RAPID ORTHODONTIC LENGTHENING OF THE MAXILLA IN PRIMATES - A PILOT-STUDY

Orthodontic and surgical treatment of patients with maxillary retrusio n and/or midface hypoplasia is challenging. This study was designed to show that the maxilla can be successfully lengthened by surgical assi sted rapid orthopedic movement, using the principles of distraction os teogenesis. Three experimental and three control adolescent cynomolgus primates were used in this study. Metallic markers were placed in the cranial base and the maxilla and cephalometric x-ray films were taken . An orthodontic appliance was constructed with a Glen-Ross screw (Den taurum, Newtown, Pa.) oriented anteroposteriorly. Anterior supraapical osteotomies of the maxilla were carried out. Bilateral horizontal and interdental osteotomies were created between the first premolars and the canine; the anterior six tooth dental-osseo segment was completely mobilized in all animals. Beginning 1 week after surgery, the orthodo ntic appliance was opened a quarter turn every 2 days until the anteri or segment was advanced by 4 mm in two animals and 6 mm in one animal. Animals were killed at 6, 8, and 12 weeks after completion of the max illary orthopedic advancement. Computerized tomographic scans of the m axillae were completed, and the specimens were then prepared by routin e histologic methods for examination by light microscopy. The computer ized tomographic scans showed bone deposition in the osteotomy sites, which was confirmed by histologic observations. Since this technique d emonstrated repair by bone rather than soft connective tissue in the o steotomy sites, this procedure could be a useful method of treating mi dface retrusion.