Deguchi T, McNamara J A
Department of Orthodontics, Matsumoto Dental University, Nagano,
Am J Orthod Dentofacial Orthop. 1999 Feb;115(2):175-82. doi: 10.1016/s0889-5406(99)70346-x.
The purpose of the present study is to examine the effects of an orthopedic force produced by chincup treatment in patients with Class III malocclusion. Anteroposterior maxillary and mandibular changes were examined as were changes in the vertical dimension. Further, the possibility of posterior displacement of temporomandibular joints in treated Class III subjects was evaluated. Serial lateral headfilms of 22 young females (average age, 9 years), who had received chincup therapy were compared with those of 20 skeletal Class III subjects of similar age who received no treatment during the interval studied. A computerized x-y coordinate program was applied to analyze the cephalometric landmarks and measurements. The treated group showed improvement of the skeletal Class III pattern associated with a slight increase (0.8 degrees per year) in SNA and a slight decrease (-0.7 degrees per year) in SNB and also a decreased gonial angle. The distance from the condyle to the chin (Co-Gn or effective mandibular length) increased significantly less in the treated group in comparison with controls. Increases in lower anterior facial height were not different between the treated and untreated groups. In addition, the cranial base angles N-S-Ba and N-S-Ar showed no statistical difference between groups, but these angles tended to increase with time in both groups. Basion and Articulare showed almost the same amount of backward and downward movement in both groups. The results of this study indicate that the primary effect of chincup therapy was in producing a reduction in mandibular growth increments during the period studied. Maxillary growth was not affected during treatment. Further, the results of this study fail to support the hypothesis that chincup appliance significantly induces the posterior displacement of the glenoid fossa.
本研究的目的是探讨颏兜治疗对III类错牙合患者所产生的矫形力的影响。对上颌和下颌的前后向变化以及垂直方向的变化进行了研究。此外，还评估了接受治疗的III类患者颞下颌关节后移的可能性。将22名接受颏兜治疗的年轻女性（平均年龄9岁）的系列头颅侧位片与20名年龄相仿的骨骼III类受试者在研究期间未接受治疗的头颅侧位片进行了比较。应用计算机化的x-y坐标程序分析头影测量标志点和测量值。治疗组的骨骼III类模式有所改善，SNA略有增加（每年0.8度），SNB略有下降（每年-0.7度），下颌角也减小。与对照组相比，治疗组髁突至颏部的距离（Co-Gn或有效下颌长度）增加明显较少。治疗组和未治疗组在下前牙面部高度增加方面无差异。此外，颅底角N-S-Ba和N-S-Ar在两组间无统计学差异，但两组这些角度均随时间有增加趋势。两组中，颅底点和关节点向后下移动的量几乎相同。本研究结果表明，颏兜治疗的主要作用是在所研究期间使下颌生长增量减少。治疗期间上颌生长未受影响。此外，本研究结果未能支持颏兜矫治器显著诱导关节窝后移这一假说。
