单侧后牙反患者髁突位置与牙弓宽度不调关系的研究

Correlation between condylar position and arch transverse discrepancy in patients with unilateral posterior crossbite

摘要:

目的：研究单侧后牙反患者髁突正中关系位（centric relation，CR）与最大牙尖交错位（maximum intercuspation，MI）髁突三维偏移的特点，分析牙弓宽度对髁突偏移的影响，为单侧后牙反患者正畸治疗计划的制定提供参考。方法：选取符合纳入标准的单侧后牙反患者33例与个别正常者33例，测量单侧后牙反患者牙弓宽度，使用架与髁突位置测量仪（mea－sure condyle displacement，MCD）记录受试者CR位和MI位的髁突位置在三维方向的差异及咬合变化情况，并采用独立样本t检验、配对样本t检验、person相关性检验进行统计学分析。结果：①试验组CR-MI不调的阳性率大于对照组（χ2=38.018，P=0.000）。②试验组反侧髁突CR-MI垂直向偏移量大于非反侧（t=2.719，P=0.010），两侧髁突CR-MI矢状向偏移量无统计学差异（t=-0.134，P=0.894）。③单侧后牙反组上牙弓宽度小于对照组（t=-4.008，P=0.000），2组间下牙弓宽度无统计学差异（t=1.653，P=0.103）；试验组上下牙弓宽度差异与髁突CR-MI所有方向偏移量均无明显相关性。④试验组与对照组干扰发生率为 90.91%与66.67%，经卡方检验具有统计学意义（χ2=5.802，P=0.033）。结论：单侧后牙反患者中，上颌牙弓宽度不足对髁突CR-MI偏移有影响，其中对垂直向偏移量的影响最为明显，因此在制定治疗计划前应对髁突移位情况进行评估，以期在真实的下颌位置与咬合情况下做出合适的诊断。

Abstract:

Objective：To investigate the condylar position differences in three dimensions between centric relation（CR） and maximum intercuspation（MI） in patients with unilateral posterior crossbite and to explore the possible correlation between transverse discrepen－cy and CR-MI displacement. Methods：Thirty-three unilateral posterior crossbite cases（experimental group） and thirty-three normal occlusion cases（control group） were evaluated. Mounting dental casts on articulator with CR bite record and Roth centric registration technique was employed. The three dimensional condylar displacements between CR and MI were measued by measure condyle displacement（MCD）. The arch width of the first molar were measured by digital caliper. Independent t-test，paired t-tests and pearson correlation were used to do statistical analysis；P<0.05 signifies statistical significance. Results：（1）The positive rate of CR-MI dis－crepency in the unilateral posterior crossbite group was higher than that in the normal occlusion group（χ2=38.018，P=0.000）. （2）In the experimental group，the distraction of the condyles was significantly greater on the crossbite side than on uncrossbite side in the vertical plane（t=2.719，P=0.010）. The condylar displacement observed in sagittal plane showed no significant difference between two sides（t=-0.134，P=0.894）. （3）Maxillary intermolar width was significantly smaller in the experimental group than in control group（t=-4.008，P=0.000）；the lower arch width showed no significant differences between groups（t=1.653，P=0.103）. There was no significant corre－lation between transverse arch discrepency and CR-MI displacement in three dimensional directions. （4）The positive rate of occlusion interferences in experimental group（90.91%） was significant higher than that in control group（66.67%， χ2=5.802，P=0.033）. The oc－clusion interferences were mostly found on the posterior teeth. Conclusion：Transverse arch discrepancy influence condyle position in patients with unilateral posterior crossbite. Among them，the vertical displacement is the most significant one. In order to get better treatment，it is important to measure the condylar dis－placement and unmask real jaw relationship before the compre－hensive orthodontic treatment starts.