1999 Volume 27 Issue 1 Pages 43-52
Orthopedic appliances such as a chincap and maxillary protraction appliance (MPA) are well employed for skeletal class in patients to correct their anterior crossbite and intermaxilary discrepancy. The purpose of the present study was to evaluate morphological changes of skeletal and dental structures using forty-six growing girls (average age, 10 years 3 months), who had received MPA as the first-stage treatment. The results were as followings ; 1. During MPA treatment, forward displacement of the maxilla with counter-clockwise rotation and backward and downward displacement of the mandible, which resulted in 3.5 ° increase in ANB angle, were observed. 2. As indicated by 3.6° and 2.9° decrease in functional occlusal plane (FOP) and conventional occlusal plane (COP), respectively, flattening of the occlusal plane was observed. 3. Wits appraisal base on FOP changed from -10.1 mm to -4.3mm (5.8mm increase). Wits appraisal (COP) changed from -8.1 mm to -2.4 mm (5.7 mm increase). 4. Increase in Wits value was largely associated with flattening of the occlusal plane. These results indicate that MPA treatment is effective not only for correction of class IE skeletal profile, but also for flattening of the occlusal plane, which would be benefit for the final construction of occlusion.
