Comparative Evaluation of Mechanical Properties Between CAD/CAM-Milled and 3D-Printed Dental Zirconia: A Systematic Review and Meta-Analysis

The field of dental restorations continues to demand durable prosthetic materials with a focus on esthetic appeal. This systematic review and meta-analysis compared the mechanical properties and bonding performance of computer-aided design (CAD)/computer-aided manufacturing (CAM)-milled and three-dimensionally (3D) printed zirconia fixed dental prostheses. A systematic search of major databases identified 15 eligible recent in vitro studies. Random-effects meta-analyses (based on standard mean deviation) and heterogeneity (I²) and sensitivity analyses were performed. The meta-analysis showed no significant differences between the groups in flexural strength, hardness, density, bond strength, and fracture toughness. However, heterogeneity remained high, reflecting possible differences in the build orientation, additive manufacturing technique, and sintering protocols. A qualitative analysis of the literature also revealed that milled zirconia was generally associated with greater consistency in strength, hardness, and accuracy. Three-dimensionally printed zirconia, while more variable due to porosity and processing factors, frequently reached clinically acceptable values, with certain orientations achieving flexural and bonding strengths equal to or surpassing those of milled zirconia. Both fabrication methods benefited from surface treatments, and artificial aging confirmed stability within functional ranges. Overall, CAD/CAM-milled zirconia remains the benchmark for predictability; however, advances in additive manufacturing suggest a growing potential for 3D-printed zirconia in complex restorations.