A critical analysis of the degree of conversion of resin-based luting cements

Objective: this study analyzed the degree of conversion (dc%) of four resin-based cements (all ceram,enforce,rely x arc and variolink ii) activated by two modes (chemical and dual),and evaluated the decrease of dc% in the dual mode promoted by the interposition of a 2.0-mm-thick ips empress 2 disc. material and methods: in the chemical activation,the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. in the dual activation,after mixing,the cements were light-activated at 650 mw/cm2 for 40 s. in a third group,the cements were light-activated through a 2.0-mm-thick ips empress 2 disc. the dc% was evaluated in a ft-ir spectrometer equipped with an attenuated total reflectance crystal (atr). the data were analyzed by two-way anova and tukey's hsd test. results: for all resin-based cements,the dc% was significantly higher with dual activation,followed by dual activation through ips empress 2,and chemical activation (p<0.05). irrespective of the activation mode,rely x presented the highest dc% (p<0.05). chemically activated variolink and all ceram showed the worst results (p<0.05). the dc% decreased significantly when activation was performed through a 2.0-mm-thick ips empress 2 disc (p<0.05). conclusions: the results of the present study suggest that resin-based cements could present low dc% when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of ips-empress 2.