Biocompatibility of Orthodontic Resins: In vitro Evaluation of Monomer Leaching and Cytotoxic Effects

The aim of this study was to investigate the effect of orthodontic resins on cell survival and to evaluate monomer leaching both before and after resin polymerization. Materials and methods: 3T3 mouse fibroblasts were exposed to three cured and uncured orthodontic resins. Cellular viability was assessed by Alamar Blue assay after 24, 48 and 72 h. High Performance Liquid Chromatography was used to measure the amount of monomers released by the tested samples. Data were analyzed by means of ANOVA and Tukey’s test (p<0.05). All tested materials exerted a cytotoxic response. Cytotoxicity tests showed that the uncured samples were more cytotoxic than the polymerized ones. A time-dependent reduction in cellular viability was found. Monomer release analyses indicated a higher elution of Triethylene Glycol Dimethacrylate (TEGDMA) compared to Bisphenol A Glycidyl Methacrylate. TEGDMA release was higher in the uncured samples and showed a time-dependent pattern. Our results showed the role of resin curing in determining the cytotoxic effect of orthodontic resins and suggested that the differences in the chemical composition of resin matrix appeared to be much more related to the decrease in cell viability than the amount of monomer leaching from orthodontic resins. Clinicians should pay greater attention to resin curing after bracket placement in order to reduce the potentially dangerous effect of monomer release.