Objectives: This study evaluated the impact of various lining materials on the fracture resistance of CAD/CAM ceramic onlays subjected to thermo-mechanical cyclic loading.
Materials and methods: Forty-eight teeth were randomly assigned to four main groups of twelve specimens each according to the lining material used (n=12): group 1, control group with no lining material; group 2, Biodentin; group 3, Cention Forte and group 4, resin modified glass ionomer (Fuji II LC). Then, each group was separated into two subgroups (n=6), one of which was tested immediately and the other after thermo-mechanical cyclic loading. Standardized IPS e.max ZirCAD ceramic onlays were fabricated with CAD/CAM and bonded on all specimens. The fracture resistance of each group was measured using a universal testing machine. Data were statistically analyzed using the Shapiro-Wilk, one-way ANOVA, student's t-test and post-hoc tukey tests.
Results: One-way ANOVA revealed statistically non-significant differences among experimental groups (p<0.05) except for a significant difference between both Biodentin, Fuji II groups and the control group after thermo-mechanical cyclic loading (p= 0.001). Moreover, post-hoc tukey test revealed a significant difference between Fuji II group without cyclic loading and Fuji II group after thermo-mechanical cyclic loading (p < 0.05).
Conclusions: Within the parameters of this study, the various types of lining materials had significant difference in fracture resistance, as Fuji II showed the most favorable outcome, however, it showed a significant deterioration upon thermo-mechanical cyclic loading.
Clinical relevance: Ceramic onlays with various lining materials may be a viable approach for the restoration of molars.