锥形束CT在三维数字化牙模建立中的初步应用

A pilot study on the accuracy of digital model reconstructed by cone beam CT

目的:研究应用锥形束CT(CBCT)采集数字化牙模的可靠性。方法:选择口腔正畸科门诊下颌前牙拥挤需要进行正畸治疗的成人患者共10例,常规取下颌印模并灌制成牙模型。应用NewTomCBCT,选择6inch视野扫描石膏模型,重建三维数字牙模。由同一操作者间隔1周分别对石膏模型和数字模型的右下颌第一前磨牙宽度、牙弓宽度、牙弓长度和下前牙宽度等测量项目进行2次测量。应用配对t检验分析各测量项目在石膏模型和数字化模型测量间的差异,计算同一测量项目间隔1周并比较2种模型前后2次测量的绝对差别程度。采用SPSS13.0软件包对数据进行统计学处理。结果:2种模型上测量右下颌第一前磨牙宽度、牙弓宽度、牙弓长度、右下颌第一切牙宽度均无统计学差异。但在石膏模型上,测量所有下前牙宽度之和大于数字化模型上的测量值,有统计学差异(P<0.05)。同一测量者在石膏模型上前后2次测量差值绝对值和数字化模型差值绝对值无显著差异(P>0.05)。结论:CBCT生成的数字化牙模型,与石膏模型线距测量结果的差别无显著性,应用CBCT重建的三维数字化牙模型可作为研究模型来存储、测量。

PURPOSE：To study the feasibility of digital model produced by cone beam CT.METHODS：Ten patients seeking orthodontic treatment with congested lower incisors were enrolled in this study.Plaster models of the lower arch were made using routing method.Digital model was reconstructed from these plaster models by NewTom 3G cone beam CT with 6 inch model.Linear measurements including right first premolar width, arch width, arch length, right first incisor width, all incisors and canines width, were done on the lower arch on plaster models with calipers.The same measurements on digital model were made using software Simplant Pro11.04.Linear measurements were repeated one week later on both plaster and digital model.Paired t test was used to determine the difference between the linear measurements on both models.The absolute measurements errors of two models were compared using paired t test.All statistical analysis was performed using SPSS13.0 software package.RESULTS：The linear measurements of the digital model slightly underestimated the real plaster model, but no significant difference of the linear measurements was seen between the plaster model and the digital model.The value of all of the lower incisors and canines width of plaster models was significantly higher than that of digital model.Mean absolute difference of different measurement of digital model was not significant from that of plaster model.CONCLUSION：Digital model using CBCT is feasible for the linear measurement and storage.