磁力Twin-block矫治器对骨性Ⅱ类错(牙合)矫治效果的研究

Treatment effects of magnetic Twin-block appliance for class Ⅱ cases

目的评价并探讨磁力 Twin-block 矫治器矫治Ⅱ类错(牙合)的临床疗效和矫治机制,为正畸临床提供参考。方法对13例替牙列晚期或恒牙列早期的安氏Ⅱ类错袷患者进行磁力 Twin-block矫治器矫治,矫治前后拍摄头颅侧位 X 线片。分别于戴矫治器前1周内(T1)、戴 Twin-block 矫治器后4个月(T2)、矫治结束后1周内(T3)和矫治结束1年后(T4)对患者的双侧颞下颌关节行螺旋 CT扫描和多平面图像重建;对 Twin-block 矫治前后39项头影测量项目进行配对 t 检验。结果 11例患者 T2期髁突矢状位和副矢状位以及大部分患者其他重建平面图像上均显示髁突后上部有生长改建的双轮廓影像;部分患者 T2和 T3期图像中出现髁突"分叉"的影像。头影测量显示,与矫治前相比,矫治后 Co-Gn 增加(5.31±2.10)mm,B-vert.pl 增加(3.23±1.39)mm,U1-SN 减少(4.73±4.39)°,L1-MP 增加(4.65±4.42)°,L6-vert.p1和 L6-MP 分别增加(4.85±1.18)mm 和(2.69±1.48)mm。患者Ⅱ类骨面型改善。结论磁力 Twin-block 矫治过程中患者髁突后上部发生明显的骨生长改建;该矫治器对处于生长发育期的Ⅱ类错(牙合)患者有显著的矫治作用。

Objective To evaluate the effects of magnetic Twin-block appliance in the treatment of skeletal class Ⅱ cases. Methods The magnetic Twin-block appliance was embedded with two pairs of neodymiumiron-boron （Nd2Fe14B） rare earth permanent magnets in the upper and lower inclined planes of Twin-block appliance. The sample comprised of 13 skeletal class Ⅱ patients in the late mixed or early permanent dentition treated by magnetic Twin-block appliance. Cephalometric films were taken before and after treatment. Helix CT images of the temporomandibular joint （TMJ） in all patients were examined before treatment （T1）, during treatment （4 months after appliance placement,T2）, after treatment （T3） and one year after treatment （T4）. Results A double contour image was detected in the superior posterior part of the condylar head on the pesudosagittal reconstruction plane pictures of T2 in 11 patients. The double contour image could be observed in most patients as well. This image also exhibited on the pictures of T3 in several patients. On the pictures of T2 and T3 in some patients, interruption of cortical bone and ＂bifurcation phenomenon＂ of condyles were shown. Pictures of T1 and T4 were similar and no signs of remodeling of TMJ were observed. Cephalometric analysis revealed significant changes in the maxillofacial structure after treatment. The profile of patients improved. Conclusions Bone remodeling of condyle occurred during the magnetic Twin-block treatment in class Ⅱ patients. Magnetic Twin-block appliance was effective in the treatment of the growing skeletal class Ⅱ patients.