应用Damon技术矫治上颌牙列拥挤的牙弓测量分析

Arch perimeter changes on non-extraction correction of dental crowding with Damon appliance

目的:分析和探讨不同牙龄阶段使用Damon矫治技术非拔牙治疗上颌牙列拥挤的机制。方法:选取24例骨性I类上颌拥挤大于5mm的病例,采用Damon矫治技术进行非拔牙正畸治疗,按照治疗前第二磨牙萌出情况分为未萌出组(G1)9例和已萌出组(G2)15例。对2组患者治疗前和上颌牙列排齐后作模型和X线头影测量,使用SPSS15.0软件包作t检验,比较2组间差异,逐步回归分析牙弓周长变化与牙弓长度及牙弓宽度各指标变化间的关系。结果:上颌牙列排齐后,牙弓长度、前磨牙间宽度和磨牙间宽度均显著增加,但增加量2组间无显著差异。逐步回归分析显示,牙弓周长的增加(Y)与牙弓长度的变化(X1)和前磨牙区牙弓宽度的变化(X2)高度相关,回归方程为Y=1.35X1+0.63X2+1.77。切牙唇向移动和第一磨牙远中移动量G1组分别为1.2mm和2.4mm,G2组分别为2.5mm和0.9mm,2组有显著差异(P<0.05)。结论:Damon技术主要通过增加牙弓长度和前磨牙间牙弓宽度来增加牙弓周长,从而达到非拔牙治疗牙列拥挤的目的。除前牙唇向移动外,在第二磨牙萌出前,可由第一磨牙远中移动获得间隙。

PURPOSE： To clarify the arch perimeter changes and the mechanism of Damon technique on the correction of dental crowding with non-extraction approach in different dental stages. METHODS： 24 patients with non-extraction Damon appliance treatment were reviewed. They had Class I skeletal pattern and upper arch crowding more than 5mm. They were divided into 2 groups according to the eruption of upper second molars,with 9 subjects in group G1 （second molar unernpted） and 15 subjects in group G2 （second molar erupted）. The dental casts and cephalometric radiophotographs were analyzed before and after the upper arch crowding correction. The difference between the two groups was analyzed with SPSS15.0 software package. RESULTS： Significant increase in upper arch length and arch width were noted after the correction of crowding, with no significantly difference between the two groups. Stepwise regression analysis indicated that the increase in arch length （X1） and inter-bicuspid arch width （X2） were predictive of the increase in arch perimeter （Y）, with the equation of Y=1.35X1＋0.63X2＋1.77. Both molar distalization and incisor protrusion contributed to the increase in arch length, which were 2.4mm and 1.2mm in G1 group, and 0.9mm and 2.5mm in G2 group. The difference between two groups was statistically significant （P〈0.05）. CONCLUSIONS： During the correction of upper arch crowding with non-extraction Damon technique, arch perimeter is gained by the increase in both arch length and inter-bicuspid arch width. In addition to the labial movement of incisors, space can be provided by the distal movement of the first molars before the eruption of second molars.