EFFECT OF HEAT TREATMENT ON CYTOTOXICITY OF UNIVERSAL ADHESIVES: CELL VIABILITY ANALYSIS

Resumo

Objective: To assess, in vitro, the cytotoxicity of three Universal self-etching adhesives (Ambar, Single Bond, Tetric N Bond) subjected to heat treatment before photopolymerization, in an NIH/3T3 fibroblast cell culture. Methods: Samples were divided into three groups: 1) no heat treatment (control), 2) 37°C and 3) 60°C heat treatment before photopolymerization. Cements were light-cured immediately and immersed in DMEM media for the extraction of possibly uncured products after 24 hours and 7 days. The specimen surface area to medium volume ratio was 3 cm²/mL, according to ISO 10993-12. Cultures containing 0.5 mL of NIH/3T3 fibroblasts per well at a concentration of 0.4x10⁵ cells/mL were cultured on specific extracts for each sample in a humidified incubator at a temperature of 37ºC and 5% of CO₂. Data were statistically analyzed with ANOVA and post-hoc Student-Newman-Keuls Results: Adhesive cytotoxicity increased with time, as shown by the higher values observed at 7 days. In the 24-hour analysis, no differences were observed in cytotoxicity levels between the adhesives heated at 60°C and the control group. In the group heated at 37°C, Tetric N Bond showed higher levels of cytotoxicity. All adhesives heated at 60°C showed reduced cytotoxicity levels when compared with those heated at 37°C. At 7 days, all samples treated with 60°C air stream showed lower cytotoxicity levels. Conclusion: Heat treatment at 60°C should be considered as a strategy to reduce the cytotoxicity of adhesives, as evidenced by the results observed both at 24 hours and at 7 days of analysis.