Abstract:

Objective

To investigate the skeletal fuction of face mask maxillary protraction combined with rapid maxillary expansion（RME） and its effect on correction of molar relationship examine the effect of the forward movement of maxillary “A” point and the rotation of mandibular mental region on the profile of class Ⅲmalocclusion.

Methods

Seventeen subjects in early permanent dentition with anterior cross bite treated by face mask and RME were included. Cephalometric radiographs were taken before treatment and after treatment for analysis. Twenty three items were included in the cephalometrics.Paired student t-test was performed to analyze the data.

Results

Maxillary “A” point was measured moving forward by 3.41±1.63 mm，whereas no significant change in Y axis which stood for the prominence of the mental region was observed. The change in A point was negatively related to the Y axis.

Conclusion

Forward movement of maxilla and mandibular clockwise rotation account for the major profile improvement. Mesial movement and the extrusion of the upper molar play an pivotal role in molar relation correction.

Key words: Maxillary protraction, Skeletal cross bite, Mandibular