Cytotoxicity of orthodontic bonding adhesive resins on human oral fibroblasts

Twelve discs of each adhesive were prepared and aged for 1, 3, 5, and 7 days in Dulbecco's Modified Eagle's Medium (DMEM). Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the difference between the groups was tested by analysis of variance and Tukey tests (alpha = 0.05). After 1 day of storage, the no-mix adhesive showed moderate cytotoxic effects (P < 0.05), while the light-cured and flowable adhesives were essentially non-cytotoxic. Ageing considerably reduced the cytotoxicity of the no-mix adhesive. On days 5 and 7 of the experiment, the cell viability of three adhesives did not differ significantly (P > 0.05), but cell viability was slightly reduced on day 7. Moderate cytotoxic effects of no-mix adhesive on the first day of the experiment suggest that care should be taken to protect dentists and patients when these adhesives are being handled. Despite higher resin components, the flowable adhesive showed excellent biocompatibility.