The aim of this study is to evaluate the degree of conversion of light-cured resin cement subjected to activation through the interposition of lithium disilicate ceramic produced according to two manufacturing techniques. Cylindrical specimens of RelyX™ Veneer resin cement were generated based on each manufacturing technique (CAD/CAM—computer aided design/computer assisted manufacturing, n = 5 or pressed ceramic technique, n = 5). Next, the specimens were washed in distilled water, dried with absorbent paper and stored in containers filled with distilled water at 37 °C for 24 h. Specimens from each group were subjected to attenuated total reflectance Fourier transform infrared (ATR-FTIR) in order to evaluate their degree of conversion. Data about the degree of conversion (%) were subjected to analysis of variance and to Student’s t-test (α = 0.05%). The degree of conversion of RelyX™ Veneer was statistically higher in the CAD/CAM manufacturing technique (39.83 ± 0.35%) than in the Press one (37.59 ± 0.62%). The light-cured resin cement activated through ceramic structure reinforced with lithium disilicate generated through the CAD/CAM manufacturing technique showed higher degree of conversion than the one generated through the Press manufacturing technique.