Ex vivo biocompatibility tests of regular and white forms of mineral trioxide aggregate

AIM: To examine the genotoxicity and cytotoxicity of regular and white mineral trioxide aggregate (MTA) ex vivo by the single-cell gel (comet) assay and trypan blue exclusion test, respectively. METHODOLOGY: Aliquots of 1 x 10(4) Chinese hamster ovary cells were incubated at 37 degrees C for 3 h with grey and white forms of MTA at final concentrations ranging from 1 to 1,000 microg mL(-1). The negative control group was treated with vehicle control phosphate buffer solution for 3 h at 37 degrees C and the positive control group was treated with methyl metasulfonate (at 1 microg mL(-1)) for 1 h at 37 degrees C. After incubation, the cells were centrifuged at 180 g for 5 min and washed twice with fresh medium and resuspended with fresh medium. Each individual treatment was repeated three times consecutively to ensure reproducibility. Parameters from single-cell gel (comet) and cytotoxicity assays were assessed by the Kruskal-Wallis nonparametric test. RESULTS: Neither compounds produced genotoxic effects with respect to the single-cell gel (comet) assay in all concentrations evaluated. In the same way, the dose-response relationships of all compounds tested at concentrations ranging from 1 to 1,000 microg mL(-1) on cell viability assessed by the trypan blue assay displayed no statistically significant differences (P > 0.05) for either endodontic material. CONCLUSIONS: Regular (grey) and white MTA are not genotoxins and do not induce cellular death.