Curing efficiency of four self-etching, self-adhesive resin cements.

OBJECTIVES To evaluate the degree of cure (%DC) of four self-etching, self-adhesive resin cements, and one conventional resin cement, in their self- and dual-curing mode. METHODS The self-etching, self-adhesive resin cements studied were RelyX Unicem (3M ESPE AG), Maxcem (Kerr Corporation), Biscem (Bisco, Inc.) and Multilink Sprint (Ivoclar Vivadent AG) and the classic resin cement was Multilink Automix (Ivoclar Vivadent AG). Twelve specimens of each material (1.8 mm x 4 mm x 4 mm) were prepared in room temperature (23+/-1) degrees C following the manufacturers' instructions. Six of them were treated as dual-cured, thus irradiated for 20 s with a halogen light curing unit and left undisturbed for 5 min. The other six were treated as self-cured and were not irradiated, but left in dark and dry conditions for 10 min. The assessment of the %DC was made using micro-ATR FTIR spectrometry. RESULTS The %DC in their self-curing mode was very low (10.82-24.93%), with Multilink Sprint exhibiting the highest values among the five. In the dual-curing mode the values obtained were also low (26.40-41.52%), with the exception of Multilink Automix (61.36%). Maxcem was found to have the lowest DC. SIGNIFICANCE The low %DC found raises questions as to whether these materials can be successfully used in clinical applications, where light attenuation takes place. Increased irradiation times could potentially lead to higher %DC, in applications where light is not completely blocked by the overlying restoration.