Mutagenicity Evaluation of a Hydrophobic Oxirane/Acrylate IPN Resin Composite

Objectives: To investigate the mutagenic potential of a new hydrophobic composite Oxirane/Acrylate Interpenetrating Network (IPN) Resin, using the Ames Salmonella/Microsome Mutagenicity Assay.
Methods: A hydrophobic Oxirane/Acrylate Interpenetrating Network Resin System (OASys) composite resin made with a multifunctional oxirane (Epalloy 8370), a multifunctional acrylate (dipenta erythritol hexaacrylate), urethane dimethacrylate and a hydrophobic fluorinated acrylate (2-perfluorooctylethylacrylate) was cured for 20 seconds. Extracts were prepared by immersing the cured OASys samples (0.2g/mL) in sterile pyrogen-free water (PFW) and incubated at 37^oC for 72 hours, following pertinent ISO guidelines. The extracts were examined for mutagenicity as is and at 1:2, 1:4 and 1:9 dilutions with the PFW. The PFW served as the negative control, and appropriate positive controls were included for each of the five Salmonella typhimurium tester strains (TA97a, TA98, TA100, TA102, and TA1537). The assay was performed in duplicate with and without S9 microsome activation. The plates were incubated at 37^oC for 48 hours, coded and scored for revertant colonies using an automatic colony counter (Protocol HR, Synoptics Ltd. Cambridge, UK). The data were analyzed by the one-way ANOVA using the statistical software GraphPad Prism (GraphPad Software, La Jolla, CA).
Results: The values of revertants for the negative and positive controls were within the historical data of the laboratory, and the results of the positive controls were all significantly higher than those of the negative controls, validating the experimental system. No dose-related increases in the number of revertants were observed in any of the five strains tested, and the mean numbers of revertants for various doses of OASys samples, including the highest dose tested, were comparable to those of the negative control.
Conclusions: Under conditions of the present study, the hydrophobic OASys resin composite is not mutagenic.