Purpose: To evaluate the polymerization degree of conversion (DC) and physical strength of dual-cure cements with tack-curing, and compare them to those with light-curing and self-curing resins.
Methods: Four dual-cure resin cements were evaluated by DC and diametral tensile strength (DTS) tests with three different polymerization methods: Light-cure (photo-polymerization 40 seconds, self-curing 30 minutes); Self-cure (self-curing 30 minutes); and Tack-cure (photo-polymerization 3 seconds, self-curing 30 minutes). Polymerization degree of conversion was determined using Fourier transform infrared spectroscopy, and calculated based on the ratio changes of aliphatic-to-aromatic C=C IR absorption peaks before and after polymerized. Specimens for DTS (n = 10) were prepared using circular molds (6.0 mm in diameter and 3.0 mm in height) and tested after 24-hour water storage. Data were analyzed by two-way ANOVA. Multiple post-hoc pairwise comparisons were performed by t-test when significant effects were found across the factors (α = 0.05). Results: The Self-cure groups had slow initial curing rate, resulting in the lower DC than both the Light-cure and Tack-cure groups. After 30 minutes of polymerization, only in the RelyX Ultimate group, light-curing resulted in higher DC than tack-curing, which resulted in higher DC than self-curing (P < 0.05). The self-cure of resin cements resulted in a significantly lower DTS only for RelyX Ultimate cement (P < 0.05). There was no significantly different DTS between the Tack-cure and Light-cure groups for all of the resin cements. For all of the three curing modes, RelyX Ultimate cements had the lowest DTS among the four cements tested in this study.