Gen Dent. 2026 Jul-Aug;74(4):70-76.
ABSTRACT
Light transmission during photopolymerization is reduced by the intrinsic optical properties of ceramics, which vary with material and thickness. The higher translucency of lithium disilicate contrasts with the chemical inertness and opacity of third-generation zirconia materials, which often require dual-cure resin cements to ensure adequate polymerization. This study evaluated the influence of the thickness of lithium disilicate and monolithic zirconia ceramics on the bond strength of a universal resin cement following 24 hours and 6 months of water storage. High-translucency lithium disilicate and zirconia discs were milled in 2 thicknesses: 0.5 mm and 1.5 mm (n = 10). Cylinders of light-curing resin cement, 0.7 mm in diameter, were bonded following application of a universal adhesive system. Microshear bond strength testing and failure mode analysis were performed after 24 hours and 6 months of water storage in a temperature-controlled, light-protected environment. Mixed generalized linear models showed that the 1.5-mm zirconia group presented a higher mean bond strength (P < 0.05). The 1.5-mm zirconia group showed significantly higher mean bond strengths than the 1.5-mm lithium disilicate group at both evaluation times (P < 0.05). Both 0.5- and 1.5-mm-thick zirconia discs exhibited a statistically significant reduction in bond strength after 6 months of storage (P < 0.05), whereas lithium disilicate discs in both thicknesses maintained stable bond strengths over time (P > 0.05). The chi-square test revealed a significant association between premature failure and the material group, with no premature failures occurring in the 0.5-mm lithium disilicate group after either storage time. Although the bond strength of zirconia decreased over time, 1.5-mm-thick zirconia still attained a higher value than 1.5-mm-thick lithium disilicate at the 6-month timepoint. Lithium disilicate showed stable values at both thicknesses.
PMID:42329617
