不同构建角度对3D打印牙预备体代型表面特征的影响

The effects of different build angle on the surface feature of 3D printed tooth preparation dies

目的:评估不同构建角度对3D打印牙预备体代型表面特征的影响。方法:构建标准牙预备体参考数据将其导入object 3D打印机中得到0°、45°及90°3组牙预备体代型(n=20)并完成后处理。采用模型扫描仪分别在打印后当天(第0天)、1、3、7、14、28 d将3组牙预备体代型扫描得到测试数据。分析牙预备体代型表面粗糙度(n=5)后,用Geomagic软件最佳拟合配准方式获得其准确度(正确度和精密度)和尺寸稳定性(n=15)的均方根误差值(RMSE)。用单因数方差分析和Tukey's或Kruskal-Wallis H检验对数据进行统计分析(α=0.05)。结果:0°或45°组的面和近远中面,90°组的近远中面和颊舌面较0°或45°组的颊舌面、90°组的面更粗糙(P<0.05)。3组代型正确度的RMSE值为:0°组(37.23±2.80)μm,>45°组(32.79±4.00)μm,>90°组(24.90±3.71)μm(P<0.05),而3组精密度(范围18.46~18.73)μm或尺寸稳定性的RMSE值(最大变化值<2μm)比较均无显著差异(P>0.05)。结论:构建角度对预备体代型表面粗糙度和正确度有显著影响,但对精密度和尺寸稳定性没有影响。所有牙预备体代型的准确度以及观察期内的尺寸稳定性都在临床可接受范围内。

Objective:To evaluate the effects of different build angles on the surface feature of 3D printed tooth preparation dies.Methods:A standard tooth preparation reference data was constructed and imported into the object 3D printer to obtain 0°,45°and 90°tooth preparation dies(n=20),and the post-processing was completed.Then,the 3 groups of tooth preparation dies were scanned by model scanner on the day after printing(day 0),1,3,7,14,and 28 days respectively to obtain test data.After analyzing the surface roughness of the dies(n=5),the best-fit-algorithm method of Geomagic software was used to obtain the root mean square error(RMSE)value of its accuracy(trueness and precision)and the dimensional stability(n=15).Statistical analysis of the data was performed using one-way ANOVA and Tukey’s or Kruskal-Wallis H test(α=0.05).Results:The occlusal and mesio-distal surfaces of the 0°or 45°group,and the mesio-distal and bucco-lingual surfaces of the 90°group were rougher than those of the 0°or 45°group,and the occlusal surface of the 90°group(P<0.05).The RMSE values for the trueness(μm)of the groups 0°,45°and 90°were 37.23±2.80,32.79±4.00 and 24.90±3.71 respectively(P<0.05),while there was no significant difference in the RMSE value of the precision(range 18.46~18.73)μm and the dimensional stability(maximum change value<2μm)among the 3 groups(P>0.05).Conclusion:Under the conditions of this experiment,the build angle has a significant effect on the surface roughness and trueness of the preparation die,but not on the precision and dimensional stability.All preparation dies were clinically acceptable for accuracy and dimensional stability over the observation period.