Influence of Vita Enamic Hybrid Ceramic with Different Thicknesses and Translucencies on the Polymerization of Light-Cured Resin Cement: An In Vitro Study

This study was conducted to evaluate the effect of the CAD/CAM (computer-aided design/computer-aided manufacturing) hybrid ceramic material (Vita Enamic, Vita Zahnfabrik, Bad Säckingen, Germany) in different thicknesses and translucencies on the light irradiance and the obtained radiant exposure, and to measure the Vickers microhardness (HV) and the degree of conversion (DC%) of the light-cured resin cement (Variolink Esthetic LC, Ivoclar Vivadent, Liechtenstein); polymerized by the Vita Enamic samples with different thicknesses and translucencies.The study comprised the polymerization of light-cured resin cement samples through blocks of different thicknesses ranging from 1.0 to 3.0 mm, and two degrees of translucency, namely, translucent and highly translucent Vita Enamic sectional blocks. Light attenuation by the Vita Enamic sections was measured using visible light transmission spectrometry, verifying the accuracy of resin curing (MARC light collector, Bluelight Analytics, Canada). The radiant exposure (RE; in J/cm³) or the energy reaching the resin cement samples through Vita Enamic sections during polymerization as well as during polymerization of the resin cement samples directly without the interposition of Vita Enamic sections (control group) was measured. The polymerization efficiency of resin cement was evaluated by using HV and DC% of resin cement using Fourier transform infrared spectroscopy.The data were analyzed for normality using the Kolmogorov-Smirnov and Shapiro-Wilk tests, which indicated non-normal distribution. Non-parametric Kruskal-Wallis tests were used to determine statistical significance, with Dunn's post-hoc tests for multiple comparisons when significance was detected.Normality tests (Kolmogorov-Smirnov and Shapiro- Wilk) applied to raw data showed that the data were not normally distributed. The nonparametric Kruskal-Wallis test was used to determine statistical significance. If significance was found, multiple comparisons of the groups were tested using Dunn's post-hoc test.The results showed a statistically significant decrease in RE (J/cm3), HV, and DC% with increasing thickness of the Vita Enamic sections. On the other hand, despite the decrease in RE (J/cm³), HV, and DC% with translucent compared with the same section thickness of the highly translucent Vita Enamic hybrid ceramic, the differences were not statistically significant.Within the limitations of this study, it can be concluded that increasing the thickness of the Vita Enamic hybrid ceramic sections reduces the light irradiance and the radiant exposure received, as well as the HV and the percentage of conversion of the light-cured resin cement Variolink Esthetic LC of neutral shade. In addition, the different translucency of the Vita Enamic hybrid ceramic, namely, translucent and highly translucent, had a small but nonsignificant effect on the light irradiance and the obtained radiation, as well as on the HV and percentage of conversion of the light-cured resin cement Variolink Esthetic LC of the neutral shade.