Sorption and solubility characteristics of self-adhesive resin cements

ObjectiveThe aim of this in vitro study was to evaluate some sorption characteristics [sorption (S), solubility (SL) and the percentages of mass change (Mg%), solubility (SL%) as well as sorbed liquid (S%)] of self-adhesive resin cements when immersed in distilled water and lactic acid.MethodsA disc-shaped specimen of each self-adhesive resin cements [G-Cem (GC), SmartCem™ 2 (SC2), RelyX™ U100 (R1), RelyX™ Unicem 2 (RU2)] were prepared in a split-Teflon mold and irradiated by an Optilux 501 light cure at 580 mW/cm2 for 40 s in eight overlapping sections each side. The volume of each specimen was calculated and placed inside a desiccator containing anhydrous calcium chloride, then weighed on an analytical electronic balance. Two independent groups were established according to the immersion media or liquids (distilled water and 0.01 M lactic acid) maintained at 37 °C for the time intervals: 1, 6, 12, 24, 48 and 168 h, where the sorption (S) property (μg/mm3) was calculated. However, the SL, Mg%, SL% and S% were measured after 168 h of immersion. The data were statistically analyzed by repeated measures ANOVA, one-way ANOVA and post hoc Tukey's test (p < 0.05).ResultsAnalysis of variance revealed highly significant differences between the materials for the sorption and solubility values examined with some exceptions (p < 0.05). However, independent samples T-test expressed significant differences of all the sorption values between both water and lactic acid media for the resin cements with some border significances (p > 0.05). The highest liquid's sorption was exhibited by GC material after immersion in lactic acid for 168 h period followed by SC2 (37.83 and 34.15 μg/mm3, respectively), while the lowest sorption was presented by RU2 cement after 1 h immersion period in water (3.89 μg/mm3). Stereomicroscope showed homogenous surface topography in RU2 and R1 samples, while some striated cracks and microvoids were observed in GC and SC2 materials, respectively. The SL values followed this order: RU2 < R1 < SC2 < GC.SignificanceKnowing the best self-adhesive cement that can provide less sorption and solubility values will help the dentist to choose the most suitable luting material for indirect restorations.