Methods: Thirty round-shaped samples (2mm thick and 5 mm in diameter) were prepared with two different self-etch resin-based luting cements. The samples were light-cured for 40s and placed individually in the bottom of wells of two 24-well dishes (15 wells/group). Then, 1 mL of serum-free DMEM was applied in each well and incubated for 24h. DMEM + components released from the samples (eluate) were obtained, giving rise to the following groups: G1- SmartCem 2 (Caulk Dentsply, Milford, DE, USA); G2: RelyX U200 (3M ESPE, St. Paul, Minnesota, USA). The eluates were applied on the odontoblast-like cells MDPC-23 previously seeded (30.000 cells/cm2) in wells of 24-well dishes. In control group (G3) only fresh DMEM was applied on the cells. Then, the cytotoxic effects were determined by MTT assay (cell metabolism - CM) and ALP assay (alkaline phosphatase activity - APA). The data were statistically analyzed by ANOVA and Tukey tests. ALP assay was subjected to Kruskal-Wallis and Wilcoxon statistical tests.
Results: Higher cytotoxicity, characterized by decrease in CM and APA was observed in G1 compared to G2 and G3 (control group) (p<0.05). In G2, only slight cytotoxicity was observed, which was not different from G3 (p>0.05). Considering G3 (control) as 100% of CM and APA, it was demonstrated that: G1 and G2 decreased the CM by 41% and 1%, respectively. In addition, G1 and G2 reduced the APA by 30% and 17.5% respectively.
Conclusions: Based upon the research protocol used in this study it can be concluded that the self-etch resin-based luting cement SmartCem 2 is more toxic to the MPDC-23 cells than RelyX U200.