Available online 10 October 2022
Highlights•Shear bond strength under fatigue loading and survival rates of luted ceramic sets.
•The influence of cyclic loads on the impairment of the resin adhesive interface.
•Resin cement viscosity did not affect the shear under static and fatigue loading of ceramic sets.
•Resin cement viscosity affected the bond strength of dentin and lithium disilicate.
AbstractObjectiveTo explore the effect of resin cement viscosities on the shear bond strength under static and fatigue load of lithium disilicate and dentin substrates.
MethodsBonded tri-layer samples (lithium disilicate ceramic cylinder, resin cement, and substrate – ceramic or dentin) was performed considering 2 factors (n = 15): “resin cement viscosity” (high, HV; or low, LV) and “loading mode” (static, s-SBS; or fatigue shear bond strength, f-SBS). The specimens were subjected to s-SBS (1 mm/min, 1 kN load cell) and f-SBS (cyclic fatigue, initial load: 10 N; step-size: 5 N; 10,000 cycles/step; underwater). Failure mode, topography, and finite element analysis (FEA) were performed.
ResultsThe resin cement viscosity did not influence the s-SBS and f-SBS of lithium disilicate substrate; however, it affected the bond strength to dentin, with HV presenting the worst fatigue behavior (f-SBS = 6.89 MPa). Cyclic loading in shear testing induced a notorious detrimental effect with a relevant decrease (16–56 %) in bond strength and survival rates, except for dentin substrate and LV. Most failures were adhesive. A distinct pattern comparing the disilicate and dentin was identified and FEA demonstrated that there was a stress concentration on the top of the cement layer.
SignificanceCyclic fatigue loading in shear testing has detrimental effects on the adhesive behavior and survival probabilities of bonded lithium disilicate sets, regardless of resin cement viscosity. In contrast, resin cement viscosity affects the bond strength and the survival rates of dentin substrate submitted to cyclic loading mode, in which a low viscosity results in better performance.
KeywordsAdhesion
Cementation
Ceramics
Dental bonding
Dental cements
Glass-ceramic
Shear strength
Viscosity
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