Alcan T, Keles A, Erverdi N
Department of Orthodontics, Faculty of Dentistry, University of Marmara, Istanbul, Turkey.
Am J Orthod Dentofacial Orthop. 2000 Jan;117(1):27-38. doi: 10.1016/s0889-5406(00)70245-9.
Protraction headgears are commonly used in the treatment of Class III malocclusion characterized by maxillary retrognathism. The upward and forward rotation of the maxilla during protraction is a major unwanted side effect. The aim of this study was to eliminate the upward and forward rotation of maxilla while protracting. Seventeen patients with Class III malocclusion as a result of maxillary retrognathism were treated for 3 months; their average age was 12.81 years. A full coverage acrylic cap splint-type rapid maxillary expansion appliance was cemented and activated twice a day for 5 days. After sutural separation, a maxillary modified protraction headgear was worn and 750 g of force was applied. Wilcoxon signed rank test was carried out to evaluate 42 parameters measured on cephalometric radiographs. The maxilla was displaced anteriorly by downward and backward rotation. The mandible was displaced downward and backward due to anterior elongation of the maxilla. Extrusion and lingual tipping of the upper incisors and intrusion of upper molars and downward and backward rotation of functional occlusal plane were observed. The aim of our study was achieved, which was to avoid upward and forward rotation while protracting the maxilla. In conclusion, maxillary modified protraction headgear (MMPH) can be used effectively in Class III patients with retrognathic maxilla and anterior open bite tendency.
前牵引矫治器常用于治疗以上颌后缩为特征的III类错牙合畸形。前牵引过程中上颌的向上和向前旋转是一个主要的不良副作用。本研究的目的是在牵引时消除上颌的向上和向前旋转。17例因上颌后缩导致III类错牙合畸形的患者接受了3个月的治疗；他们的平均年龄为12.81岁。佩戴全覆盖式丙烯酸帽夹式快速上颌扩弓矫治器，每天激活两次，持续5天。缝分离后，佩戴上颌改良前牵引矫治器，并施加750克的力。采用Wilcoxon符号秩检验来评估在头颅侧位片上测量的42个参数。上颌通过向下和向后旋转向前移位。由于上颌的前伸，下颌向下和向后移位。观察到上前牙的伸长和舌倾、上磨牙的压低以及功能性牙合平面的向下和向后旋转。我们的研究目的得以实现，即在牵引上颌时避免向上和向前旋转。总之，上颌改良前牵引矫治器（MMPH）可有效用于上颌后缩且有前牙开牙合倾向的III类患者。
