Dentin microshear bond strength of various luting agents to zirconia-reinforced lithium silicate ceramics

Statement of problem. Performance of adhesive and resin luting cements used to bond zirconia-reinforced lithium silicate ceramics (ZLS) to dentin has not been well established. Purpose. To examine microshear bond strength (µSBS) of etch-and-rinse adhesive system, universal adhesive and self-adhesive resin cement that were used to bond ZLS to dentin. Material and Methods. Vita Suprinity® (VS, Vita Zahnfabrik) and Celtra® Duo (CD, Dentsply Sirona) blocks were sectioned into 36 and 72 microbars (1×1×3 mm3) respectively. All VS were crystallized, while half of CD were additionally fired and defined as fired-Celtra® Duo (FCD). The others were defined as unfired-Celtra® Duo (UCD). Each microbar was cemented to each flat occlusal dentin surface of human premolar, following the adhesive luting systems: ScotchbondTM Multi-purpose (SM, 3M ESPE) and Single Bond Universal (SU, 3M ESPE) combined with RelyXTM Ultimate (RXU, 3M ESPE), and RelyXTM Unicem (U2, 3M ESPE) (n=12 per group). 24-hour µSBS was then determined, and data were analyzed using two-way ANOVA and a Tukey post-hoc test (α = .05). Failure modes were analyzed under a stereomicroscope at 40×. Results. Two-way ANOVA revealed that type of ZLS had no influence on µSBS (P=.699). In contrast, kind of adhesive luting cements and their interaction had a statistically significant effect on µSBS (P<.001 and .002 respectively). According to Tukey post-hoc test, U2 had a statistically significant lower mean µSBS regardless of the type ZLS, compared with SM and SU, while UCDU2 did not have a statistically significant difference in µSBS from UCDSU (P=.478). Conclusions. Etch-and-rinse and universal adhesive resin luting systems may be suitable for cementation of ZLS to dentin.