Fracture Toughness Of A Novel Fluorescent Full-Contour Zirconia Compared To Other Ceramics

Objectives: Determine the fracture toughness of ceramic restoration materials including a novel fluorescent zirconia.
Methods: The investigated materials are 3M Lava Plus High Translucency Zirconia (LP), 3M Lava Esthetic Fluorescent Full-Contour Zirconia (LE) and Ivoclar Vivadent IPS e.max CAD (EM). Bending bars were cut from CAD/CAM mill blanks, sintered or crystallized per manufacturer's instructions. All samples were ground and polished to final dimensions 16x4x3 mm. Sample bars (n=6) from each group were prepared and measured for KIc fracture toughness according to the ISO6872 Single-Edge-V-Notch-Beam method.
Results: Mean fracture toughness (FT) results are summarized in Table 1 and depicted in Figure 1. 2-sample-t-tests (p<0.05) were performed for all groups and statistically different groups are marked with different letters in Table 1. Mean FT values are in following order LP > LE > EM. Each group is statistically significant different to each other.
Conclusions: FT is a mechanical property defining the materials ability to resist crack propagation and allows meaningful comparisons to be made among ceramics used for structural purposes. LP shows highest FT due to the transformation toughening capability. FT of LE is reduced compared to LP due to increased cubic and decreased tetragonal crystal phase content. EM is a lithium disilicate glass-ceramic material and showed lower FT compared to both zirconia materials tested in this study.