Abstract
Introduction: The current in vitro study was designed to assess the failure mode and fracture resistance of ultrathin occlusal veneers made from different ceramic materials.
Methods: Twenty-four ultrathin occlusal veneers were fabricated on maxillary extracted first premolar teeth. Three ceramic materials were used: lithium disilicate (LDS), zirconia-reinforced lithium disilicate (ZLS), and zirconium dioxide (ZIR). An adhesive luting agent was used to adhesively bond occlusal veneers. Each sample was subjected to thermocycling, ranging from 5 to 55°C. Fracture resistance was tested using a universal testing machine, and fractured surfaces were examined with a stereomicroscope and a scanning electron microscope (SEM) to assess failure modes.
Results: A statistically significant difference was observed; the highest mean fracture resistance was observed in LDS (1741±308.3 N), followed by ZLS (1192±89.44 N), and then ZIR (866.9±60.23 N), which had the lowest mean fracture resistance. The failure mode of the ZIR group differed significantly from those of the other groups.
Conclusion: All the tested ceramic materials used as ultrathin occlusal veneers exhibited fracture loads significantly higher than the average physiological masticatory forces. Compared with the other two groups, LDS had the highest fracture resistance value. ZIR occlusal veneers exhibited more repairable fractures than LDS and ZLS.