Objectives: The aim of the present study was to investigate the conversion and acid-base reaction in self-etch resin cements.
Methods: The materials tested were: G-CEM (GC), SMART CEM2 (Dentsply), Clearfil SA CEMENT (Kuraray), BISCEM (Bisco) and EMBRACE (Pulpdent). The setting reaction was studied by FTIR spectroscopy. Spectra of the cements were taken before setting, at 8min and 1h after setting of non-irradiated and 10s irradiated specimens (standard mode, 750mW/cm2, dark storage at 37oC in all cases). The extent of free radical polymerization was assessed by measuring the amount of remaining C=C bonds (%RDB) employing the two frequency technique. For the acid-base reaction, the salt yield was evaluated (1200-950cm-1). ANOVA was used to assess the statistically significant differences (a=0.05).
Results: The %RDB was found significantly lower in non-irradiated specimens in all materials, while %RDB was found higher in 8min specimens relative to 1h. The highest salt yield was found in the non-irradiated group after 1h setting. Irradiated groups showed a lower salt yield in all resin cements, except EMBRACE which did not show evidence of an acid-base reaction.
Conclusions: The self-etch resin cements demonstrated significant differences in their setting profiles. Irradiation provided decreased %RDB values. Salt formation was delayed by light exposure in all materials.