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

Statement of problem. The performance of adhesive and resin luting cements used to bond zirconia-reinforced lithium silicate (ZLS) ceramics to dentin has not been well established. Purpose. The purpose of this in vitro study was to examine the microshear bond strength (mSBS) of an etch-and-rinse adhesive system, a universal adhesive, and a self-adhesive resin cement that were used to bond ZLS to dentin. Material and methods. VITA Suprinity (VS) and Celtra Duo (CD) blocks were sectioned into 36 and 72 microbars (1x1x3 mm). 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 a human first premolar, following the adhesive luting systems: Scotchbond Multi-purpose (SM), Single Bond Universal (SU) combined with RelyX Ultimate, and RelyX Unicem (U2) (n=12 per group). mSBS at 24 hours was then determined, and the data were analyzed by using 2-way ANOVA and a Tukey post hoc test (a=.05). Failure modes were analyzed under a stereomicroscope at x40 magnification. Results. Two-way ANOVA revealed that the type of ZLS had no influence on mSBS (P=.699). However, the kinds of adhesive luting cements and their interaction had a statistically significant effect on mSBS (P<.001 and P=.002). U2 had a statistically significant lower mean mSBS, regardless of the type of ZLS, than SM and SU (P <=.05), while UCDU2 did not show a statistically significant difference in mSBS from UCDSU (P=.478). Conclusions. Resin cement used with an etch-and-rinse and a universal adhesive agent demonstrates higher bond strength for the cementation of zirconia-reinforced lithium silicate ceramics to dentin than a self-adhesive resin cement.