Assessment of HEMA and TEGDMA induced DNA damage by multiple genotoxicological endpoints in human lymphocytes

Residual unbound resin monomers of 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) are known to diffuse in the saliva and through dentin and pulp into the blood and may affect cellular integrity. The current study was performed to investigate the genotoxic potential of both monomers in distinctly lower concentrations than known to cause cytotoxic damage.

Lymphocytes from 10 healthy volunteers were treated with HEMA (10μM-1mM) and TEGDMA (1μM-100μM) for 24h. Cell viability, apoptosis and influence on cell cycle kinetics were assessed by flowcytometry. DNA damage was determined by the alkali version of the comet assay in combination with the FPG protein and by the cytokinesis-block micronucleus (CBMN) test. Additionally, the chromosome aberration (CA) test and sister chromatid exchange (SCE) test were performed.

A slight decrease in cell viability was detected only at the highest concentration of TEGDMA. Genotoxic effects were measurable in the comet assay at 1mM of HEMA and 100μM of TEGDMA, with and without FPG protein, but not in the CBMN test or the cell cycle analysis. Contrary to these findings, a significant dose-dependent increase in the frequency of CAs and SCEs could be demonstrated in all tested concentrations.

This is the first time clastogenic responses to HEMA and TEGDMA have been detected in concentrations distinctly lower than those reported for causing cytotoxic or even genotoxic effects. These findings underline the importance of using test batteries with different genotoxicological endpoints to describe the multiple effects of both resin monomers.