MBTTM托槽系统矫正病例支抗磨牙的三维位置变化

目的:研究经MBTTM托槽系统矫正病例的支抗牙--上颌第一磨牙的三维位置变化;比较一步滑动法和两步滑动法对治疗后牙齿的轴倾度、转矩度和扭转的影响;比较横腭杆(TPA)对矫正后上磨牙轴倾度、转矩度和扭转的影响.方法:对37例上颌后牙需最大支抗的患者应用MBTTM托槽系统进行矫正,其中19例应用一步滑动法,18例应用两步滑动法.所有的病例均采用口外弓加强支抗,其中21例还使用了TPA;利用YM-2115三维测量仪和三维测量软件对患者治疗前后的上颌模型进行测量和重叠测算,得出牙齿矫正后空间位置变化.结果:矫正后上第一磨牙平均前移(4.5±1.1)mm,伸长(1.5±0.9)mm;近中舌向扭转(3±7).(一步滑动法和两步滑动法间差异无显著性;TPA组和非TPA组间差异有显著性);近中倾斜(6±4).(一步滑动法大于两步滑动法,差异有显著性);上磨牙平均发生(3±6).冠颊向转矩(一步、两步滑动法间差异无显著性).结论:应用MBTM托槽系统行拔牙矫治后,上磨牙出现冠颊向转矩、近中扭转和近中倾斜的趋势.矫治过程中,一步滑动法比两步滑动法更容易造成上磨牙的近中倾斜.TPA对抗磨牙扭转的作用较其它作用更为明显.

Cast analysis of 37 patients treated with MBTTM appliance

OBJECTIVE: To study the 3D positional changes occurring to anchor molars of 37 patients treated with MBT appliance. METHODS: Thirty-seven patients who needed maximum upper molar anchorage were divided into two treatment groups at random, group I was comprised of 19 patients whose anterior teeth were retracted en masse, and group II included 18 patients whose anterior teeth were retracted by two step. All the patients were treated with MBT appliance and headgear. Dental casts recorded before and after treatment were analyzed by YM-2115 three-dimensional digitizer and related software. The changes of anchor molar tip,torque and rotation were compared between the two groups. RESULTS: During the treatment, average anterior movement of the upper first molars was 4.53 mm, average extrusion of the upper first molars was 1.53 mm; the crown of the upper first molar tipped forward (6+/-4) degrees,torque buccally (3+/-6) degrees,and mesiolingually rotated 3.15 degrees; In en mass group, the crown of the upper first molar tipped more mesially than the two-step group, and the difference was statistically significant. CONCLUSION: Almost all the upper first molars showed the tendency to rotate and tip mesially and torque bucally; there was no statistically significant difference between the two treatment groups when upper molar positional changes were concerned except for the mesial tip of the crown.