Influence of glass-ceramics transmittance on chemomechanical properties of light- and dual-cure resin cements.

This study assessed the effects of light attenuation by glass-ceramics (IPS e.max Press, IPS e.max CAD, IPS Empress CAD, and Vita Suprinity) on the degree of conversion (DC), polymerization shrinkage stress (PSS), and microshear bond strength (µSBS) of dual-cure (RelyX Universal and RelyX Ultimate) and light-cure (Variolink N LC and Variolink Esthetic LC) resin cements. Ten slabs (12 × 12 × 1.5 mm) were fabricated from each ceramic. For light attenuation analysis (n=1), the ceramic slab was positioned onto the light-curing tip (Valo-Cordless), and the radiant emittance (mW/cm²) was measured. Resin cement cylinders (n=10) were fabricated using Tygon tubes positioned onto ceramic slabs, water-stored for 24 h, and tested for µSBS. For the PSS test, glass rods were positioned 1 mm apart, and the gap was filled with resin cement, which was light-cured. The rod displacement was considered for the calculation of PSS. The DC test (n=3) for each resin cement was conducted using a spectrometer. Surface morphology was examined by SEM (LEO 435 VP, 20 kV) at 5.000×. DC, PSS, and µSBS data were analyzed using ANOVA and Tukey's test (α = 0.05). No significant difference was observed among the resin cements for PSS. Variolink Esthetic LC showed a µSBS mean value statistically lower than RelyX Ultimate. For Suprinity, the light-cure cements showed DC mean values significantly lower than the dual-cure cements. It was possible to conclude that the ceramic slabs significantly increased the light attenuation, which affected the DC, PSS, and µSBS of all the dual- and light-cure resin cements.