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

摘要

Objective:? The purpose of this study was to evaluate the extent of polymerization and microhardness of dual-cure self-adhesive resin cements in their light-cure and self-cure modes. Materials and Methods:? Maxcem and RelyX Unicem were the self-adhesive cements tested in this study, and Panavia F2.0 was used as a control. Differential scanning calorimetry (DSC) was used to measure the extent of polymerization (or degree of conversion) of the three cements under two different curing conditions. Specimens of each material were either light-activated for 20 seconds using a halogen curing device and then allowed to self-cure for 2 hours or specimens were not exposed to the curing light and were only allowed to self-cure. In addition to the DSC, Vickers microhardness testing was performed. Results:? For all three materials, degree of conversion (DC) was better when they were light-activated. Expressed as percentages, the DC values for light-activated and self-cure specimens were 54.6 versus 40.5 for Maxcem, 54.4 versus 31.7 for RelyX Unicem, and 48.6 versus 31.4 for Panavia F2.0 (Kuraray). Vickers microhardness values followed a similar pattern. For example, the mean Vickers Hardness Number (VHN) for light-activated Unicem was 44; for self-cure only, it was 26. Conclusions:? Polymerization of dual-cure self-adhesive resin cements was similar to that of a conventional dual-cure resin cement control.