Osseointegrated titanium implants for maxillofacial protraction in monkeys

Titanium implants were placed surgically into the maxillary, zygomatic, frontal, and occipital bones of four pigtail monkeys. After a 4-month healing period, the implants were exposed and abutments were placed. Extraoral traction appliances were then attached to the abutments. The cranial implants were used to support the framework of the traction appliance; those in the facial bones were used to attach springs that delivered a protraction force. The application of force varied among animals. In animal A, the force was applied to the maxilla. In animal B, the force was applied to the zygomatic bones. Animals C and D had force applied to both the maxillary and zygomatic bones. A tensile force of 600 gm per side was maintained until approximately 8 mm of maxillary anterior displacement had occurred. This amount of movement required 12 weeks of force application in animals A and B, and 18 weeks in animals C and D. Cephalometric and dry skull analyses showed that the amount of skeletal protraction was significant. The findings also demonstrated that it was possible to control the direction of maxillary protraction. The facial implants remained immobile throughout the experiment.