Clinical study of the effect of molar inclination in adult patients with maxillary transverse deficiency treated with modified microimplant-assisted rapid palatal expansion

Objective To investigate the midpalatal suture expansion and effect of molar inclination changes in adults with maxillary transverse deficiency and treated with modified microimplant-assisted rapid palatal expansion. Methods 12 patients aged from 18 to 29 years with maxillary transverse deficiency were included(average 21.58±3.12 years, 2 male and 10 female). All of the patients were treated with modified microimplant-assisted rapid palatal expansion appliance. CBCT was taken before expansion and no more than 1 week after the end of expansion. Midpalatal suture of canine level, midpalatal suture of first molar level, maxillary first molar width, interdental angle of maxillary first molars and screw width of the appliance were measured by Dolphin Imaging 11.8 Premium software and analyzed by paired t-test in SPSS 17.0 software. Results After expansion, the increase of midpalatal suture in canine level and first molar level was (3.08±1.48) mm (2.62±1.06) mm, respectively. Maxillary first molar width widened (4.28±1.56) mm which showed significant differences(P 0.05). Comparing the width change of maxillary first molar and screw of the appliance, there is no statistical differences(P>0.05). However, the width change of midpalatal suture of molar level and screw of the appliance showed significant statistical differences(P<0.01). Conclusions Midpalatal suture of adult patients can be expanded by modified microimplant-assisted rapid palatal expansion appliance. After expansion, the maxillary first molar maintained its original physiological inclination. Key words: Microimplant-assisted rapid palatal expansion; Maxillary transverse deficiency; Adult