Polymerization Mode of Self-Adhesive, Dual-Cured Dental Resin Cements Light Cured Through Various Restorative Materials.

OBJECTIVE: The aim of this study was to investigate the polymerization mode of self-adhesive, dual-cured resin cements light-cured through overlying materials with different degree of translucency by measuring the degree of conversion (DC).

MATERIALS AND METHODS: Three kinds of self-adhesive, dual-cured resin cements (G-CEM LinkAce(TM) , Maxcem Elite(TM) , and BisCem(®) ) were light-cured through three different restorative materials that included porcelain-fused metal (PFM), zirconia, and lithium disilicate. Polymerization kinetics were continuously evaluated using infrared spectroscopy after 0, 5, 10, and 30 min and 2 weeks of mixing. Data were statistically analyzed using two-way analysis of variance (ANOVA), one-way ANOVA, and Tukey's multiple-comparison test (α = 0.05).

RESULTS: Regardless of the kind of resin cement, the light-cured groups showed higher DC than did the autopolymerization group under PFM at any point of time (p < 0.05). The time taken by the cements to achieve statistically similar DC between the zirconia and lithium disilicate groups increased in the following order: G-CEM LinkAce(TM) , BisCem(®) , and Maxcem Elite(TM) (p < 0.05). CONCLUSIONS: The degree of translucency of the restorative material can be a significant variable determining the polymerization aspects of self-adhesive, dual-cured resin cements. The resin cements light-cured through lithium disilicate and zirconia showed higher DC than that shown by cements cured under PFM at any measurement time. The lithium disilicate and zirconia groups showed differences in the early stage of polymerization for G-CEM LinkAce(TM) and BisCem(®) ; however, the differences diminished at 2 weeks.

CLINICAL SIGNIFICANCE: Chemical polymerization is not sufficient to cause the resin cement to achieve the highest polymerization not only in early stage, but also in late stage of polymerization. The sensitivity to the intensity of the light was different for each resin cement. Special clinical steps to compensate for the attenuated light intensity seem to be necessary for the resin cements which are susceptible to light intensity.(J Esthet Restor Dent, 2017).