Ngan P, Hägg U, Yiu C, Merwin D, Wei S H
Department of Orthodontics, West Virginia University, School of Dentistry, Morgantown, USA.
Eur J Orthod. 1996 Apr;18(2):151-68. doi: 10.1093/ejo/18.2.151.
A prospective clinical trial was conducted to determine the skeletal and dental contributions to the correction of overjet and overbite in Class III patients. Thirty patients (12 males and 18 females with a mean age of 8.4 +/- 1.7 years) were treated consecutively with protraction headgear and fixed maxillary expansion appliances. For each patient, a lateral cephalogram was taken 6 months before treatment (T0); immediately before treatment (T1); and 6 months after treatment (T2). The time period (T1-T0) represented changes due to 6 months of growth without treatment; (T2-T1) represented 6 months of growth and treatment. Each patient served as his/her own control. Cephalometric analysis described by Björk (1947) and Pancherz (1982a,b) was used. Sagittal and vertical measurements were made along the occlusal plane (OLs) and the occlusal plane perpendicular (OLp), and superimposed on the mid-sagittal cranial structure. The results revealed the following: with 6 months of treatment, all subjects were treated to Class I or overcorrected to Class I or Class II dental arch relationships. Overjet and sagittal molar relationships improved by an average of 6.2 and 4.5 mm, respectively. This was a result of 1.8 mm of forward maxillary growth, a 2.5-mm of backward movement of the mandible, a 1.7-mm of labial movement of maxillary incisors, a 0.2-mm of lingual movement of mandibular incisors, and a 0.2-mm of greater mesial movement of maxillary than mandibular molars. The mean overbite reduction was 2.6 mm. Maxillary and mandibular molars were erupted occlusally by 0.9 and 1.4 mm, respectively. The mandibular plane angle was increased by 1.5 degrees and the lower facial height by 2.9 mm. Individual variations in response to maxillary protraction was large for most of the parameters tested. Significant differences in treatment changes between male and female subjects were found only in the vertical eruption of mandibular incisors and maxillary and mandibular molars. These results demonstrate that significant overjet and overbite corrections can be obtained with 6 months of maxillary protraction in combination with a fixed expansion appliance.
进行了一项前瞻性临床试验，以确定骨骼和牙齿对III类患者覆盖和覆合矫正的贡献。连续治疗30例患者（12例男性和18例女性，平均年龄8.4±1.7岁），使用前方牵引矫治器和固定上颌扩弓矫治器。对每位患者，在治疗前6个月（T0）、治疗前即刻（T1）和治疗后6个月（T2）拍摄头颅侧位片。时间段（T1 - T0）代表未经治疗的6个月生长导致的变化；（T2 - T1）代表6个月的生长和治疗。每位患者均作为自身对照。采用Björk（1947年）和Pancherz（1982a、b）描述的头影测量分析法。沿咬合平面（OLs）和垂直于咬合平面（OLp）进行矢状和垂直测量，并叠加于正中矢状颅结构上。结果显示如下：经过6个月治疗，所有受试者均矫治为I类或过度矫治为I类或II类牙弓关系。覆盖和矢状磨牙关系平均分别改善6.2 mm和4.5 mm。这是由于上颌向前生长1.8 mm、下颌向后移动2.5 mm、上颌切牙唇向移动1.7 mm、下颌切牙舌向移动0.2 mm以及上颌磨牙比下颌磨牙多近中移动0.2 mm所致。平均覆合减小2.6 mm。上颌和下颌磨牙分别向咬合面萌出0.9 mm和1.4 mm。下颌平面角增加1.5度，面下高增加2.9 mm。对于大多数测试参数，上颌前牵引的个体反应差异较大。仅在下颌切牙以及上颌和下颌磨牙的垂直萌出方面，发现男性和女性受试者的治疗变化存在显著差异。这些结果表明，结合固定扩弓矫治器进行6个月的上颌前牵引可获得显著的覆盖和覆合矫正。
