Sorção de água e solubilidade de cimentos resinosos autoadesivos: análise comparativa após ciclagem térmica

Abstract

The aim of this study was to compare water sorption and solubility among different self-adhesive resin cements subjected to different periods of thermocycling. Standardized cylindrical specimens (6 mm × 2 mm) were prepared using a silicone mold for each resin cement group (n = 7 per group): RelyX U200, Panavia SA Luting, seT PP, and RelyX Universal. All cements were handled and dispensed into the mold placed on a glass plate using their self-mixing system. Before polymerization, the inserted cement was covered with a polyester strip, followed by a glass slide, which was pressed manually for 60 s and kept under a 500 g weight for 60 s. After the chemical reaction, light curing with an LED (~1200 mW/cm²) was performed for 60 s. The specimens were stored in a desiccator and weighed daily on an analytical balance until mass 1 stabilized, after which they were subjected to 2,500 and 5,000 thermal cycles in water, alternating between 5ºC and 55ºC. At the end of each period, specimens were weighed to record mass 2 and returned to the desiccator until mass 3 stabilized. Water sorption and solubility values (µg/mm³) were calculated and analyzed using ANOVA followed by Tukey’s test (α = 0.05). The seT PP cement showed the highest water sorption in both thermocycling periods and the highest solubility (p < 0.001). RelyX U200 showed a negative mean solubility, significantly lower than Panavia SA Luting (p = 0.033) and RelyX Universal (p = 0.015), which showed intermediate performance and were similar to each other (p > 0.05). Increasing the number of thermal cycles from 2,500 to 5,000 did not result in statistically significant differences in sorption or solubility in any group. It was concluded that cements with higher hydrophilic monomer content, such as seT PP, exhibit greater water sorption and solubility after thermocycling, indicating lower chemical stability.