Metabolism Of L929 Cells After Contact With Acrylic Resins. Part 1: Acrylic Denture Base Resins

Objective: The purpose of this study was to evaluate the effectiveness of complementary heat treatment and water storagein reducing cytotoxicity of acrylic resins denture bases used in Brazil by the MTT assay. Material and Methods: First, nine specimens were fabricated from metal matrix in the form of discs with 14 mm indiameter and 1.2 mm of thick. Immediately after making, 24 or 48 hours after storage in distilled water, the samples of heat-polymerized resins were divided into 3 groups (n = 3) according to the type of thermal treatment: Group 1: sampleswere individually exposed to microwave energy (500 W for 3 minutes); Group 2: samples were immersed in water at 550C for 60 minutes; Group 3: samples did not receive heat treatment. To prepare the extracts, 3 samples of each group wereplaced into vials containing 3 mL of culture medium and stored at 37°C for 24 hours. L929 cells were used and the MTTassay was performed to analyze the cellular metabolism. Two-factor analysis of variance was used to detect significantamong groups at 5% significance. Results: After statistical analysis, the materials were classified according to the cytotoxic effect: non-cytotoxic, slightly cytotoxic;moderately cytotoxic; and strongly cytotoxic. The results showed that the resins ranged from moderately cytotoxicto non-cytotoxic, but no statistically significant difference among experimental groups. Furthermore, the water storage andthermal treatments reduced the cytotoxicity of the resins. Conclusions: It was concluded that the resins studied are potentially toxic and that treatments can decrease their cytotoxicity.