Influence of crystallization and adhesive cementation on the fracture resistance of CAD/CAM advanced lithium disilicate and zirconia-reinforced lithium silicate ceramics after thermocycling

Background Advancements in CAD/CAM glass-ceramics have expanded their use in esthetic dentistry; however, the combined influence of thermal processing and adhesive cementation on their mechanical performance after oral aging remains unclear. Aim To assess the effect of crystallization and adhesive cementation on the fracture resistance of CAD/CAM advanced lithium disilicate and zirconia-reinforced lithium silicate ceramics following thermocycling. Materials and methods Eighty monolithic crowns ( n = 10/group) were milled from advanced lithium disilicate (CEREC Tessera™), lithium disilicate (e.max CAD), and zirconia-reinforced lithium silicate (Vita Suprinity®). Specimens were assigned to eight groups based on crystallization and cementation protocols. All crowns underwent 5,000 thermocycles (5 °C–55 °C). Fracture resistance was measured under static compressive loading. Non-parametric tests (Kruskal–Wallis and Mann–Whitney U with Bonferroni correction) were applied ( α = 0.05). Results Both crystallization and adhesive cementation significantly increased fracture resistance ( p < 0.05). Crystallized-cemented specimens exhibited the highest values across all materials. Tessera™ crystallized-cemented crowns reached the highest mean fracture resistance (1,918.9 ± 246.3 N), outperforming e.max CAD and Vita Suprinity®. Conclusion Crystallization and adhesive cementation exert synergistic benefits on the fracture resistance of CAD/CAM glass-ceramic crowns after thermocycling. Adhering to recommended thermal cycles and adhesive protocols is essential to optimize mechanical reliability and long-term performance.