Methods: Samples of resins (Lucitone 550, Clássico, Onda Cryl, Vipi Cril and Vipi Wave) were fabricated, stored in distilled water for 0, 24 and 48 hours at 37ºC and divided into 3 groups: 1) no heat-treatment; 2) water bath at 55ºC for 60 minutes and 3) microwave irradiation for 3 minutes at 500 W. Eluates of the materials were prepared by placing each disk into a sterile glass vial with 1 mL of Eagle's medium. L929 fibroblasts were cultivated in 96 well culture plates and incubated for 24 hours at 37ºC. Thereafter, the culture medium was replaced by 100µL of eluate and 100µL of fresh medium, and incubated for more 24 hours at 37ºC. The MTT assay was used to determine the cytotoxicity of the materials. The results were evaluated in accordance with ISO 10993-5, in which inhibition of less than 25% counts as non-cytotoxic, 25% to 50% as slight, 50% to 75% as moderate and more than 75% as highly cytotoxic.
Results: Both heat-treatments decreased cytotoxicity of the resins Vipi Cril and Vipi Wave. After specimens fabrication, the acrylic resin Vipi Wave was the most cytotoxic, followed by Lucitone 550. Storage in water for 24 hours reduced the cytotoxicity of the acrylic resins Clássico and Lucitone 550, while the cytotoxicity of Onda Cryl was decreased after 48 hours of storage.
Conclusions: The resin Lucitone 550 was considered non toxic after storage in water or heat-treatment, having the highest number of viable cells in these conditions. The acrylic resin Vipi Wave ranged from strongly to slightly cytotoxic.