The effect of curing mode on extent of polymerization and microhardness of dual-cured, self-adhesive resin cements.

PURPOSE To compare the effect of curing mode (self- or light-cure) on the extent of polymerization (%EP1 as measured using differential scanning calorimetry, (DSC) and microhardness of two dual-cured, self-adhesive resin cements, using a conventional, dual-cured resin cement as control. METHODS Small amounts of the commercial self-adhesive cements Maxcem and RelyX Unicem or Panavia F2.0 dual-cure resin based cement used as control were polymerized within the DSC chamber at 35 degrees C under a nitrogen atmosphere. 10 specimens were light-cured immediately (20 seconds, 600 mW/cm2) and left undisturbed for 2 hours and 10 additional specimens were left to self-cure in the dark for 2 hours. Following DSC treatment, microhardness of the specimens was measured (Vickers). For each test parameter, data were analyzed with a two-way ANOVA and the Tukey post hoc test. RESULTS %EP and microhardness of all cements were higher when the light-cure mode of dual-activation was used (P<0.05) instead of only self-curing. No significant difference in %EP was found between either self-adhesive cement or the control using either the light- or self-curing modes. In the light-activated mode, the conventional, dual-cure control cement demonstrated lower microhardness than the self-adhesive cements (P<0.05).