三种牙颌模型扫描仪牙尖交错牙合三维重建精度评价

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（牙合）（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（3Shape D700,3Shape A/S,丹麦）,B（ZENO@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骀后,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△Zn=Zn-ZR.采用配对￡检验比较Zn与ZR的差异,采用单因素方差分析对△Zn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（牙合）重建精度分别为：0.00＆#177;0.43mm,0.26＆#177;0.36mm,0.08＆#177;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.

Accuracy of intercuspal occlusion in 3D reconstruction of three dental cast scanning systems

Objective： To evaluate the accuracy of the intercuspal occlusion （ICO） in the three-dimensional full dentition models reconstructed by 3 commercially available dental cast scanning systems for clinical application. Methods： A pair of maxilla-mandibular die-stone casts was made with the ICO relation fixed by wax record. 45 feature points were marked and numbered on the models. Respective feature points from maxillary and mandibular models were paired up and the distance （Z） between the pair of the two feature points were measured. The contact measuring arm （Faro） was used to obtain the space coordinates of each feature points, and ZR was determined as the reference by using the software Geomagic Studio. The 3 dental cast scanning systems including System A（3Shape D700, 3Shape A/S, Denmark）, Systme B（ZENO~ Scan, Weiland, German）, System C（Activityl02, Smart Optics, German） were used to reconstruct the occlusal relation of the maxilla-mandibular models. The feature points were chosen based on the true models and digital models, and the distance Z, （ZA, ZB, Zc） were measured. The errors of the occlusal relation of the reconstruction procedure was identified by the calculation of AZn=Zo-ZR. The compared t-tests were used to analyze the variable differences between Z. and ZR. The one-way ANOVA test was used to analyze the variable differences among the 3 dental scanning systems. Results： There was a statistically significant difference between ZB and ZR （P〈0.05）. The accuracy of the occlusal relation of the reconstruc- tions of Systems A, B, and C are 0.00＋ 0.43ram, 0.26＋ 0.36mm, 0.08＋ 0.34mm. There was a significant difference between ZA and ZB. Conclusion： The 3D reconstructions of the occlusal relations of maxillomandibular full-dentition cast models were established by the 3 dental cast scanning systems. The accuracies of the 3 scanning systems were A〉C〉B, and the pre- cisions of them were C〉B〉A.