Glutaraldehyde-containing dentin bonding agents are mutagens in mammalian cells in vitro

The mutagenic potential of glutaraldehyde-containing dentin bonding agents was shown in previous studies using a bacterial gene mutation assay, the Ames test. However, current strategies of genotoxicity testing and regulatory requirements for the biological evaluation of medical devices recommend a battery of tests that indicate induced mutations in prokaryotic and eukaryotic cells. Accordingly, the mutagenicity of three glutaraldehyde-containing bonding agents (Syntac adhesive, Prisma Universal Bond 3 adhesive, and Gluma 3) was investigated using a quantitative mammalian cell gene mutation assay (V79/HPRT test) in the present investigation. The materials were extracted in dimethyl sulfoxide (0.1 g/2 mL) for 24 h and original extracts were then serially diluted in cell culture medium before exposure to V79 cells. Cytotoxic and mutagenic effects were observed with identical concentrations of extracts of the different test materials. There was a moderate decrease of the number of surviving cells immediately after the end of exposure. Mutagenicity at the hprt locus in V79 cells was found with all materials tested, and the increases in the absolute numbers of mutants were dose dependent. The mutant frequencies were about 15- (Syntac adhesive and Gluma 3) to 20-fold (Prisma UB3 adhesive) higher than solvent control values. Since other substances than glutaraldehyde may be responsible for the mutagenic effects in mammalian cells in this study, work is currently in progress to identify the individual mutagenic compounds of dentin adhesives and related composite materials.