Genotoxic and cytotoxic potential of methacrylate-based orthodontic adhesives.

OBJECTIVES: The biocompatibility of methacrylate-based adhesives is a topic that is intensively discussed in dentistry. Since only limited evidence concerning the cyto- and genotoxicity of orthodontic adhesives is available, the aim of this study was to measure the genotoxic potential of seven orthodontic methacrylate-based adhesives. MATERIALS AND METHODS: The XTT assay was utilized to determine the cytotoxicity of Assure Plus, Assure Bonding Resin, ExciTE F, OptiBond Solo Plus, Scotchbond Universal Adhesive, Transbond MIP, and Transbond XT after an incubation period of 24 h on human gingival fibroblasts. We also performed the γH2AX assay to explore the genotoxic potential of the adhesives within cytotoxic dose ranges after an incubation period of 6 h. RESULTS: The XTT assay showed a concentration-dependent reduction in cell viability. The decrease in cellular viability was in the same dose range most significant for Assure Plus, rendering it the adhesive material with the highest cytotoxicity. Employing the γH2AX assay, a concentration-dependent increase in H2AX phosphorylation was detected, indicating induction of DNA damage. CONCLUSIONS: For most products, a linear correlation between the material concentration and γH2AX foci was observed. The most severe effect on γH2AX focus induction was found for Transbond MIP, which was the only adhesive in the test group containing the co-initiator diphenyliodonium hexafluorophosphate (DPIHP). CLINICAL RELEVANCE: The data indicate that orthodontic adhesives, notably Transbond MIP, bear a genotoxic potential. Since the study was performed with in vitro cultivated cells, a direct translation of the findings to in vivo exposure conditions should be considered with great diligence.

Is there a Genotoxic Potential of Endodontic Root Materials?

BACKGROUND: Leakage of components from endodontic materials (EM) can occur in case of apical extrusion into the periapical tissue. Therefore, an important prerequisite, besides the mechanical properties of the EM, is a high biocompatibility. In the present study, we elucidated the genotoxic potential of EMs of different base composition by utilizing the -H2AX assay. METHODS: For investigation of the genotoxic potential of EM, supernatants of commercially available EM were prepared and dilutions were applied to human gingival fibroblasts. Non-toxic doses of EM were determined by cell viability assay. For the -H2AX assay, human gingival fibroblasts were incubated with predefined concentrations of the supernatants, which were found not to reduce cell viability. Hydrogen peroxide was utilized as positive control. Cells were fixed 1, 6 and 24 hours after addition of the supernatant to the medium, followed by immunostaining for -H2AX. For scoring of -H2AX foci, automated foci counting was performed in at least 80 cells per experiment and time point. The experiments were repeated at least twice. RESULTS: In contrast to hydrogen peroxide treated cells, no elevated -H2AX levels were detected in cells incubated with the EM supernatants. CONCLUSIONS: Samples treated with EM supernatants showed no elevated levels of -H2AX foci, e.g., no genotoxicity. Therefore, all types of EM seem to meet the standard to be called a biocompatible dental material in terms of genotoxicity, and, therefore, the application seems safe.