Colour matching of composite resin cements with their corresponding try-in pastes.

Two shades of four resin cements (Calibra, Clearfil Esthetic, Insure, Variolink II), in light- and dual-curing modes, were tested for colour matching with their corresponding try-in pastes, immediately after photopolymerization and after 24-hour dry and dark storage. Colour measurements were performed for 0.8 mm-thick specimens through a 0.8mm-thick ceramic plate. For each resin cement, colour differences (deltaE) were calculated between the two curing modes, and between the corresponding try-in paste, at baseline and after 24h. deltaE>0 values were detected between all resin cements and their try-in pastes, which were brand/shade/curing mode depended. The try-in pastes of the Variolink II system demonstrated the best colour matching (deltaE<2). Try-in pastes of Calibra and Insure, at both curing modes, did not match at an acceptable value, the shade of their corresponding resin cements (deltaE>3.3). Calibra presented the highest colour differences. deltaE values of the Clearfil Esthetic system immediately after photo-activation ranged between 2 and 3 units. A ceramic restoration may fail aesthetically as a result of not acceptable colour match (deltaE>3.3) between the shade of certain resin cements and their relevant try-in pastes.