The article introduces a new method for three-dimensional reproduction of edentulous dental casts,and wax occlusion rims with jaw relation by using a commercial high-speed line laser scanner and reverse engineering software and evaluates the method’s accuracy in vitro.The method comprises three main steps：（i）acquisition of the three-dimensional stereolithography data of maxillary and mandibular edentulous dental casts and wax occlusion rims;（ii）acquisition of the three-dimensional stereolithography data of jaw relations;and（iii）registration of these data with the reverse engineering software and completing reconstruction.To evaluate the accuracy of this method,dental casts and wax occlusion rims of 10 edentulous patients were used.The lengths of eight lines between common anatomic landmarks were measured directly on the casts and occlusion rims by using a vernier caliper and on the three-dimensional computerized images by using the software measurement tool.The direct data were considered as the true values.The paired-samples t-test was used for statistical analysis.The mean differences between the direct and the computerized measurements were mostly less than 0.04 mm and were not significant（P.0.05）.Statistical significance among 10 patients was assessed using one-way analysis of variance（P,0.05）.The result showed that the 10 patients were considered statistically no significant.Therefore,accurate three-dimensional reproduction of the edentulous dental casts,wax occlusion rims,and jaw relations was achieved.The proposed method enables the visualization of occlusion from different views and would help to meet the demand for the computer-aided design of removable complete dentures.
目的:定量评价3种商品化三维光学牙颌模型扫描仪全牙列模型牙尖交错(intercuspal occlusion,ICO)三维重建精度,为临床选择应用提供参考。方法:用超硬石膏灌制一副标准上下颌牙列石膏模型,咬合蜡固定ICO空间位置关系,在模型上确定45个特征点并顺序编号。分别选取上下颌模型上特征点进行配对,测量特征点对间距离Z。用机械接触式柔性测量机械臂R直接获取特征点空间坐标后软件测量获取参考值(ZR);运用A(3Sh ape D700,3Sh ape A/S,丹麦),B(ZENO R Scan,Weiland,德国)、C(Activity102,Smart Optics,德国)3种牙颌模型扫描仪重建全牙列模型牙尖交错后,人机交互选取模型对应特征点、软件测量获取测量值(Zn:ZA、ZB、ZC)。定义测量误差ΔZn=Zn-ZR。采用配对t检验比较Zn与ZR的差异,采用单因素方差分析对ΔZn进行分析,比较3种牙颌模型之间的差异。结果:B扫描仪测量值与参考值差异有统计学意义,P<0.05。3种商品化三维光学牙颌模型扫描仪模型牙尖交错重建精度分别为:0.00±0.43mm,0.26±0.36mm,0.08±0.34mm。A、B扫描仪模型ICO三维重建精度差异有统计学意义,P<0.05。结论:模型ICO三维重建正确度:A>C>B,精密度:C>B>A。
