层厚对3D打印临时冠精度的影响研究

A study of the effects of layer thickness on the accuracy of 3D printed temporary crowns

目的:评价层厚对3D打印临时冠精度(正确度和精密度)的影响。方法:对标准下颌石膏模型的46进行基牙预备,用模型扫描仪扫描基牙并将模型导入牙科CAD软件,在软件中设计临时冠并将临时冠STL作为参考模型导出。在3D打印机中分别用50、100μm层厚打印临时冠(n=10)并完成后处理,然后用模型扫描仪扫描临时冠获得实验模型。Geomagic软件对模型进行编辑、配准后执行3D偏差分析获得其精度偏差。独立样本t检验对数据进行分析(α=0.05)。结果:50μm层厚组打印临时冠在内表面、内部区域的正确度高于100μm层厚组,在边缘区域的正确度低于100μm组(P<0.05)。100μm层厚组打印临时冠内表面精密度高于50μm组(P<0.05)。100μm层厚组打印临时冠所需时间约为50μm组的一半。结论:100μm和50μm层厚3D打印临时冠的精度均在临床可接受范围内。100μm层厚打印临时冠的正确度低于50μm层厚,但精密度更高;100μm层厚参数打印临时冠耗时少。

Objective:To study the effects of layer thickness on the accuracy(trueness and precision)of 3D printed temporary crowns.Methods:A standard stone mandibular cast with prepared 46 was digitized,and its standard tessellation language(STL)file was imported into a dental software program CAD.A virtual temporary crown was designed and saved in an STL file as the reference model.A DLP printer was used to print temporary crowns with the thickness of 50μm and 100μm(n=10)respectively.All the crowns were post-processed and digitized with a laboratory scanner as the experimental models.Geomagic Wrap software was used to edit and register models,and a 3D deviation analysis was executed to obtain the root mean square(RMS).Statistical analysis of the data was performed through t-test(α=0.05).Results:The trueness of the printed temporary crowns in the intaglio surface and internal region was higher in the 50μm layer thickness group than in the 100μm layer thickness group,and lower in the marginal region than in the 100μm group(P<0.05);the precision of printing temporary crowns in the intaglio surface was higher in the 100μm layer thickness group than in the 50μm layer thickness group(P<0.05).The time required for the printing temporary crowns in the 100μm layer thickness group was about half of that in the 50μm group.Conclusion:The accuracy of the printed temporary crowns with the thickness of 50μm and 100μm are clinically accepted.100μm layer thickness printed temporary crowns with lower trueness than 50μm layer thickness,but with higher precision.100μm layer thickness is recommended for clinical use for less time consumption.