Effect of LED Light-Curing Spectral Emission Profile on Light-Cured Resin Cement Degree of Conversion

Clinical Relevance The use of multipeak LED light-curing guarantees efficiency on light activation of Ivocerin-containing light-cured resin cement. SUMMARY Objectives: This study evaluated the degree of conversion (DC) of an Ivocerin-containing light-cured resin cement activated through different thicknesses of a lithium disilicate glass ceramic using two LED light-curing units (LCUs). It also evaluated the influence of the glass ceramic interposition on irradiance and the spectral emission profile of the LED LCUs. Methods and Materials: Medium-translucency lithium disilicate glass ceramic specimens of 0.3-, 1.0-, and 2.0-mm thickness were heat pressed. A single-peak and a multipeak LED LCU were selected. Irradiance and spectral emission profile were assessed, the light transmittance was calculated, and the translucency parameter was determined for each thickness. DC was calculated after 20, 40, or 60 seconds of light activation by attenuated total reflection/Fourier-transform infrared spectroscopy. DC data were analyzed using three-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) test, irradiance and light transmittance data were analyzed using two-way ANOVA and the Tukey HSD. Spearman’s correlation test was performed between the translucency parameter and light transmittance (α=0.05). Results: DC ranged from 71.1% to 80.1%, increasing significantly from light activation of 20 to 60 seconds. Irradiance ranged from 186.1 to 2013.5 mW/cm2. Multipeak LED LCU showed higher DC and irradiance than single-peak LED LCU. Light transmittance ranged from 13.3% to 61.5%. Irradiance and light transmittance decreased as lithium disilicate glass ceramic thickness increased. The translucency parameter and light transmittance showed a significant correlation. Conclusions: Multipeak LED LCU allows higher C=C conversion with shorter light activation time of Ivocerin-containing light-cured resin cement with an interposed medium-translucency lithium disilicate glass ceramic.