An investigation of the microstructure and mechanical properties of dental zirconia manufactured by digital light processing 3D printing.

This study was performed to investigate the microstructure and mechanical properties of dental zirconia manufactured by digital light processing (DLP) 3D printing and the clinical application prospects of this material.The experiment (DLP) group was zirconia manufactured by DLP 3D printing, and the control (MILL) group was milled zirconia. The density, grain size, and phase composition were measured to study the microstructure. Flexural strength was measured by using three-point bending tests, while Vickers hardness was determined through a Vickers hardness tester. Fracture toughness was tested using the single-edge V-notched beam method.Zirconia density of the DLP group was (6.019 8±0.021 3) g·cm-3, and the average grain size was (0.603 0±0.032 6) μm, but without statistical difference with the corresponding values of the MILL group (P>0.05). Tetragonal phase was found in the X-ray diffraction patterns of the DLP and MILL groups. The flexural strength of the DLP group was (1 012.7±125.5) MPa, and Vickers hardness was (1 238.5±10.8) HV1, which was slightly lower than that of the MILL group (P<0.05). The fracture toughness of the DLP group was (7.22±0.81) MPa·m1/2, which was not statistically different from that of the MILL group (P>0.05).Zirconia manufactured by DLP 3D printing had microstructure and mechanical properties similar to those of the milled zirconia. Only the flexural strength and the Vickers hardness of the experimental zirconia were slightly lower than those of the milled zirconia. Therefore, DLP-manufactured zirconia has a promising future for clinical use.目的: 研究数字光处理技术（DLP）打印牙科氧化锆的微观结构特征和机械性能，探究其临床应用前景。方法: 以DLP技术制备氧化锆为实验组（DLP组），数控切削技术制备氧化锆为对照组（MILL组），测定其密度、晶粒尺寸及晶相构成以研究微观结构特征，采用三点弯曲试验测量挠曲强度，硬度计测量维氏硬度，单边V槽横梁法测量断裂韧度。结果: DLP组氧化锆的密度为（6.019 8±0.021 3）g·cm-3，晶粒尺寸为（0.603 0±0.032 6）μm，与MILL组无统计学差异（P>0.05）。2组氧化锆晶相构成均为单一四方相。DLP组氧化锆挠曲强度为（1 012.7±125.5）MPa，维氏硬度为（1 238.5±10.8）HV1，略低于MILL组（P<0.05）；断裂韧度为（7.22±0.81）MPa·m1/2，与MILL组无统计学差异（P>0.05）。结论: DLP成型牙科氧化锆的微观结构特征及机械性能与切削氧化锆相似，仅挠曲强度和维氏硬度略低于切削氧化锆，显示出良好的临床应用前景。.