Objective: Maxillary protractive appliance is conventionally used to promote the maxillary forward movement or to regulate the mandibular growth. However, side effects to the maxillary teeth often become the problem. The purpose of this study is to evaluate the effects of the maxillary protractive appliance in combination with miniscrew.
Methods: Patients were randomly divided into two groups. In one group, the patients were treated with only maxillary protractive appliance (FM group). In the other group, the patients were treated with maxillary protractive appliance in combination with miniscrew (FM+IA group). A lingual arch with soldered hooks was placed to maxillary arch in both groups and protracitve force of 500-600g was applied from the face mask to the hooks. The patients were instructed to use it for 12 hours a day. In FM+IA group, a miniscrew was inserted in the palate and the lingual arch was fixed to it.
Results: The mobility and the falling of the miniscrew were not observed during a treatment period. From the result of the lateral cephalometric analysis, SNA and ANB significantly increased in the FM+IA group than those in the FM group. The angle of the labial inclination of maxillary incisors was significantly increased in the FM group than that in the FM+IA group.
Conclusions: The miniscrew in the palate had high stability. It was suggested that the maxillary protractive appliance in combination with miniscrew has reduced side effects and deliver orthopedic forces to a maxillary complex more efficiently.