Mechanical, translucency, tribological resistance, and biocompatibility of lithium disilicate glass-ceramics produced by ZrO2 doping and digital light processing for dental prosthesis.

BACKGROUND: Lithium disilicate glass-ceramics (LDGCs) have become one of the most widely used dental prosthesis materials in clinical practice due to their excellent esthetics, biocompatibility, and enamel-like wear resistance. However, their inherent brittleness, limited mechanical strength, and progressive wear under long-term service have restricted their application in high-stress posterior regions. Herein, this study aims to develop zirconia (ZrO2)-reinforced LDGCs and systematically investigate the effects of ZrO2 content on microstructure evolution and mechanical, translucency, tribological, and biological performance.

METHODS: ZrO2-reinforced LDGCs (LDGCxZ, where x = 0, 2, 4, 6 mol%, designated as LDGC, LDGC2Z, LDGC4Z, and LDGC6Z) with varying ZrO2 contents were fabricated via a melting-derived powder processing route combined with digital light processing, debinding, and sintering. The LDGCxZ samples were systematically characterized for their microstructural evolution, mechanical properties, translucency, tribological behavior, and biological performance through biaxial flexural strength testing, aging resistance testing, Weibull two-parameter distribution analysis, Vickers hardness testing, fracture toughness analysis, nanoindentation testing, and tribological evaluation. Furthermore, hemocompatibility, cytocompatibility, and in vivo biological responses were assessed using hemolysis assays, CCK-8 assays, live/dead staining, phalloidin staining, subcutaneous implantation in a rat model, and comprehensive biosafety evaluation.

RESULTS: 4 mol% ZrO2 doping optimally refines the crystalline structure, creating a homogeneous dual-phase of Li2Si2O5 and Li2SiO3 that effectively minimizes internal defects, while excessive doping (6 mol%) leads to abnormal grain growth and porosity formation. Impressively, the sintered LDGC4Z sample (4 mol% ZrO2) exhibited exceptional comprehensive properties: a flexural strength of ∼294 MPa, fracture toughness of ∼4.1 MPa m1/2, elastic modulus of ∼111.4 GPa, and Vickers hardness of ∼644 HV, and a 150% enhancement in the translucency parameter, alongside superior anti-aging resistance and tribological behavior closely matching that of natural enamel. The LDGC4Z sample also confirmed excellent hemocompatibility, favorable cytocompatibility with human gingival epithelial cells, and stable tissue integration in subcutaneous implantation models. Collectively, the LDGC4Z sample exhibited balanced improvements in mechanical properties, translucency, tribological resistance, and biological safety, while suppressing LTD through microstructural refinement, stress engineering, and crystallization control. Significance This study overcomes the limitations of conventional processing routes by integrating DLP 3D printing technology with a ZrO2 compositional regulation strategy within the LDGC system. A novel LDGC system that combines printability, microstructural controllability, and mechanical compatibility was successfully established, providing an essential theoretical foundation and process framework for the development of high-performance LDGC materials for dental restorations.