Evaluation of Fracture Toughness of Monolithic and Multilayered Zirconia for Prosthodontic Restorations: An In-Vitro Study

The purpose of this in-vitro study was to compare the fracture toughness of monolithic zirconia and multilayered zirconia, two commonly used materials in prosthodontic restorations. Fracture toughness is a key mechanical property that determines a material’s resistance to crack propagation under stress, which is crucial for the longevity and performance of dental restorations. A total of 20 zirconia discs (10 monolithic and 10 multilayered) were fabricated using Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) technology. The discs were subjected to loading and fracture toughness was measured using the indentation method with a Vickers micro-hardness tester. The fracture toughness values for monolithic zirconia (Group 1) were significantly higher than those for multilayered zirconia (Group 2), with mean values of 5.394 ± 0.378 MPa·m1/2and 4.358 ± 0.394 MPa·m1/2, respectively (p < 0.0001). These findings suggest that monolithic zirconia offers superior mechanical performance, making it a more suitable material for high-stress applications, while multilayered zirconia may be preferred for anterior restorations, where esthetics are prioritized. The study highlights the trade-off between mechanical strength and esthetic appeal in the selection of zirconia materials for dental restorations and provides valuable insights for optimizing material choice in clinical prosthodontics