ABSTRACT
PURPOSE: To evaluate the effect of light-curing on the immediate and delayed micro-shear bond strength (microSBS) between yttria-tetragonal zirconia polycrystal (Y-TZP) ceramics and RelyX Ultimate when using Single Bond Universal (SBU). MATERIALS AND METHODS: Y-TZP ceramic specimens were ground with #600-grit SiC paper. SBU was applied and RelyX Ultimate was mixed and placed on the Y-TZP surface. The specimens were divided into three groups depending on whether light curing was done after adhesive (SBU) and resin cement application: uncured after adhesive and uncured after resin cement application (UU); uncured after adhesive, but light cured after resin cement (UC); and light cured after adhesive and light cured resin cement (CC). The three groups were further divided depending on the timing of microSBS testing: immediate at 24 hours (UUI, UCI, CCI) and delayed at 4 weeks (UUD, UCD, CCD). microSBS was statistically analyzed using one-way ANOVA and Student-Newman-Keuls multiple comparison test (P0.05). At 4 weeks, microSBS of UUD group (24.43+/-2.88 MPa) had significantly increased over time compared to UUI group (P<0.05). The SEM results showed mixed failure in UCI and CCI group, while UUI group showed adhesive failure. CONCLUSION: Light-curing of universal adhesive before or after application of RelyX Ultimate resin cement significantly improved the immediate microSBS of resin cement to air-abrasion treated Y-TZP surface. After 4 weeks, the delayed microSBS of the non-light curing group significantly improved to the level of light-cured groups.