Self-cure after tack cure could result in a lower polymerization shrinkage in some resin-based luting cements, which is closely related to lower degree of cure.
To evaluate the effect of tack cure on polymerization shrinkage (PS) of resin-based luting cements.
One composite resin cement, Duo-Link (Duolink); two self-adhesive resin cements, RelyX U200 (U200) and G-CEM LinkAce (GCem); and one resin-modified glass ionomer cement, RelyX Luting Plus (Luting+), were used for measuring PS in light-cure (LC group), self-cure (SC group), and two tack-cure modes that were light cured (TC-LC group) or self-cured (TC-SC group) after tack cure. PS was measured by a modified bonded disc method for 1600 seconds and analyzed with two-way analysis of variance and Tukey honestly significant difference test. To investigate the effect of tack cure on light cure or self-cure, data were analyzed with an independent-samples t-test with tack cure as a variable. The significance level was 5%.
Regarding cure mode, Duolink showed a significantly lower PS in the TC-SC group compared with the other groups. Luting+ showed a significantly lower PS in the TC-SC group than in the SC group. U200 showed a significantly lower PS in the self-cure groups compared with that in the light-cure groups. The PS of GCem was not affected by cure mode. Regarding cements, Luting+ showed the highest PS, followed by GCem, Duolink, and U200 (p<0.05). Self-cure of Duolink and Luting+ was negatively affected by tack cure, while light cure was not affected. U200 and GCem were not affected by tack cure either in the self-cure or light-cure groups.
For the tested cements, tack cure decreased the PS of Duolink and Luting+ when they were self-cured after tack cure. When the cements were light cured after tack cure, PS was not affected by tack cure in any cement.