Evaluation of single-step self-etching ceramic primer and zirconia primer for bonding to zirconia-reinforced lithium silicate ceramic.

The purpose of this study was to evaluate the influence of simplified ceramic surface treatments on the microshear bond strength (μSBS) of 2 resin cements to a zirconia-reinforced lithium silicate (ZLS) material. Blocks of ZLS were sectioned to obtain a total of 90 specimens (1.5 mm thick), which were assigned to 9 different surface treatment protocols (n = 10). Either hydrofluoric acid (HF) surface conditioner or ammonium polyfluoride self-etching ceramic primer (Monobond Etch & Prime [MEP]) was used for surface treatment and then combined with different bonding strategies (Monobond N silane-based universal primer, Prosil silane coupling agent, Ambar Universal APS self-etching adhesive, and/or Signum Zirconia Bond methyl methacrylate-based bonding system [SZB]) and luting agents (Allcem or Multilink Automix dual-curing resin cement). Composite resin cylinders were bonded to ZLS with each of the cementation protocols, and the specimens were subjected to 6000 thermal cycles from 5°C to 55°C prior to the μSBS evaluation. The failure mode was analyzed with the aid of a stereoscopic loupe. Statistical analyses were performed with 1-way analysis of variance and Tukey HSD test (α = 0.05). The HF and MEP protocols resulted in significantly higher μSBS values (P < 0.001), while conditioning with SZB resulted in the lowest μSBS. Multilink Automix groups presented higher μSBS values than Allcem groups (P < 0.01). There was no statistically significant difference in the μSBS values of the MEP + Allcem groups based on whether or not an adhesive layer was applied. The failure mode was predominantly adhesive for all specimens. The results indicate that the ammonium polyfluoride-based material MEP may be used as a substitute for surface treatment with HF and silane, but the use of a zirconia primer alone is not advised for bonding to a ZLS ceramic material.