Hassan Rogina M, Ibrahim Yomna, AboELHassan Rewaa G, Azer Amir Shoukry
Conservative Dentistry Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
BMC Oral Health. 2025 Jul 24;25(1):1236. doi: 10.1186/s12903-025-06570-6.
The primary method for fabrication of zirconia restorations is subtractive manufacturing technology. This process mills restorations from large blocks using various cutting tools resulting in large amounts of waste material. 3D printing has emerged as an alternative tool for additive manufacturing of zirconia with less waste and high efficiency.
A total of 24 monolithic zirconia crowns were divided into: Group I (milled zirconia crowns) and Group II (3D printed zirconia crowns) (n = 12). The crowns were then polished and glazed then subjected to 5000 thermocycles. Fracture resistance for the crowns was measured using universal testing machine followed by estimation of Weibull modulus and characteristic strength. Fractographic analysis was done using scanning electron microscope (SEM). 72 discs (10 mm × 2 mm) were fabricated by milling and printing (n = 36) then subjected to 5000 thermocycles. The discs were used for surface roughness assessment both before (n = 12) and after (n = 12) glazing using contact profilometer and unglazed discs (n = 12) were used for microhardness which was measured by Vickers microhardness tester. Comparisons between study groups were performed using independent samples t-test. Two-way ANOVA was performed to assess the association between material (milled or printed) and glazing (glazed or unglazed) with surface roughness. Significance level was set at P-value < 0.05.
In comparison to 3D printed zirconia, the milled version exhibited comparable fracture resistance, reduced surface roughness, and increased microhardness. While both groups showed comparable fracture resistance with no significant difference (P = 0.26), the milled zirconia demonstrated significantly better surface finish (P < 0.001) and microhardness (P < 0.001). However, glazing lowered the surface roughness significantly for both milled (P < 0.001) and printed (P = 0.001) zirconia, bridging the gap in surface quality between the two fabrication techniques.
The enhanced fracture resistance and Weibull modulus of 3D printed zirconia indicate increased reliability and consistency in its mechanical properties. However, limitations of its surface properties highlight the need for further optimization before full clinical adoption.
氧化锆修复体的主要制造方法是减材制造技术。该工艺使用各种切割工具从大块材料中铣削修复体，会产生大量废料。3D打印已成为一种用于氧化锆增材制造的替代工具，具有更少的废料和更高的效率。
总共24个整体式氧化锆全冠被分为：第一组（铣削氧化锆全冠）和第二组（3D打印氧化锆全冠）（n = 12）。然后对全冠进行抛光和上釉，接着进行5000次热循环。使用万能试验机测量全冠的抗折强度，随后估算威布尔模量和特征强度。使用扫描电子显微镜（SEM）进行断口分析。通过铣削和打印制作72个圆盘（10毫米×2毫米）（n = 36），然后进行5000次热循环。使用接触式轮廓仪在（n = 12）上釉之前和之后（n = 12）对圆盘进行表面粗糙度评估，未上釉的圆盘（n = 12）用于通过维氏显微硬度计测量显微硬度。使用独立样本t检验对研究组之间进行比较。进行双向方差分析以评估材料（铣削或打印）和上釉（上釉或未上釉）与表面粗糙度之间的关联。显著性水平设定为P值<0.05。
与3D打印氧化锆相比，铣削版本表现出相当的抗折强度、更低的表面粗糙度和更高的显微硬度。虽然两组显示出相当的抗折强度且无显著差异（P = 0.26），但铣削氧化锆表现出明显更好的表面光洁度（P < 0.001）和显微硬度（P < 0.001）。然而，上釉显著降低了铣削（P < 0.001）和打印（P = 0.001）氧化锆的表面粗糙度，弥合了两种制造技术在表面质量上的差距。
3D打印氧化锆增强的抗折强度和威布尔模量表明其机械性能的可靠性和一致性有所提高。然而，其表面性能的局限性突出了在全面临床应用之前需要进一步优化。
