Comparative evaluation of fracture toughness between zirconia and lithium disilicate ceramics: An in vitro study.

Fracture toughness is a critical determinant of long-term success in all-ceramic restorations, yet comparative data between major ceramic systems remain limited. Therefore, it is of interest to evaluate and compare the fracture toughness of yttria-stabilized zirconia and lithium disilicate ceramics. Forty CAD/CAM-fabricated specimens were tested using Vickers indentation and fracture toughness was calculated via the indentation fracture method. Zirconia showed significantly higher fracture toughness (408.61 ± 44.21 MPa.m1/2) and hardness than lithium disilicate (359.40 ± 19.00 MPa.m1/2) (p <0.0001). Zirconia demonstrates superior crack resistance compared to lithium disilicate, supporting its use in high-stress clinical applications.