[Cephalometrical analysis of effects of premaxillary orthopedic treatment on maxillary growth of Wistar rats with bilateral artificial cleft palate].

OBJECTIVE: To measure the differences between the experimental group and the two controlled groups by using the cephalometric radiography technique to study the effects of premaxillary orthopedic treatments on the growth and development of maxilla.

METHODS: To make an animal model with bilateral cleft palate by surgery operation: General anesthesia was carried on by injecting 2.5% pentobarbital (25 mg/kg) into abdominal cavity, then almost the same bone of rats' palate were removed from bilateral palate. An appliance, based on the principle of Latham's appliance was made and designed for premaxillary orthopedic treatment. It was fixed in rats' palate using pins under the condition of general anesthesia. After 20 days of orthopedic treatment, the rats were anesthetized by ether, and cephalometric films were taken under self-designed cephalometer and analysed aided by computer.

RESULTS: The distances that represented the maxillary position in the posterior-anterior (PA) direction significantly increased (P < 0.05), while the angles that represented the direction of premaxillary growth significantly decreased (P < 0.05) between the experimental group and the two controlled groups. There were no significant difference between the two controlled groups.

CONCLUSION: Premaxilla of rats can be effectively moved backward and rotated downward and backward on the PA direction by appliance. The appliance can move the segment palate forward during the premaxillary backword. The appliance can stimulate maxillary growth.