快速上颌扩展在吮拇指所致开牙合治疗中的作用

 目的 探讨快速上颌扩展（rapid maxillary expansion，RME）在吮拇指所致开牙合畸形的正畸治疗中的作用。方法 选择有长期吮拇指习惯的恒牙列早期的开牙合患者10例，10～12岁，平均11.63岁，前牙区开牙合约10 mm。在进行宣教自行破除吮拇指的不良习惯3～4个月以后，对吮拇指所致的上颌及上牙弓狭窄用RME行上颌横向扩展。RME的开展速度为每日将螺旋开大0.5 mm（每日旋转2次，每次1/4圈），直至上后牙腭尖和下后牙颊尖相对为止。扩展矫治前后均取模、摄上颌前部咬合片、头颅正、侧位定位片。利用SPSS 13.0软件包对数据进行配对t检验。结果 腭中缝被打开，上颌基骨横向宽度增大，左右侧颧点间距、左右侧上颌牙槽基座点间距和左右侧上颌第一恒磨牙颊侧面最外点间距均增大，增加量分别为2.30、2.30和4.85 mm；上牙弓横向宽度增大，上颌左右侧尖牙牙尖间距及左右侧第一恒磨牙近中颊尖间距增大，上牙弓弓形得到明显改善，并为排齐牙列创造了间隙。结论 RME通过打开腭中缝增加上颌基骨宽度，在较短的治疗时间内获得所需的骨骼效应，对吮拇指导致开牙合的恒牙列早期患者矫治上颌及上牙弓狭窄疗效显著，为进一步的固定矫治纠正开牙合奠定了基础。

Therapeutical effect of rapid maxillary expansion in treating open bite due to thumb-sucking

Objective To investigate the therapeutical effect of rapid maxillary expansion (RME) in treating open bite due to thumb-sucking. Methods A sample of ten early permanent dentition patients with open bite due to thumb -ears, with the mean age of 11.63 years old. The anterior open bite was 10 mm or so. The patients underwent RME with 2 turns a day (0.25 mm per turn) until the lingual cusp of the upper molars occluding with the buccal cusp of the lower molars. Immediately before appliance insertion and at the end of active expansion, posteroanterior cephalograms, occlusal radiographs and casts were taken. Paired t test was used for statistical analysis. Results The midpalatal suture was expanded. The width of maxillary bases was increased. Bizygomatic width, maxillary width and maxillary first molar width were increased by 2.30, 2.30 and 4.85 mm in average respectively. Maxillary intermolar cusp width and maxillary intercanine cusp width were increased. The upper arch form was modified obviously, creating space required for teeth alignment. Conclusions RME treatment is able to expand the midpalatal suture and induce pronounced transverse changes at the skeletal level, which is an effective therapeutic procedure for open bite due to thumb-sucking of the early permanent dentition patients.