Evaluation of cytotoxicity of MTAD using the MTT-tetrazolium method

Previous studies have shown that MTAD (a mixture of a tetracycline isomer, an acid, and a detergent) is an effective antibacterial irrigant as a final rinse to remove the smear layer from the instrumented surface of root canals. In this investigation we examined the cytotoxicity of MTAD compared with that of commonly used irrigants and medications. L929 fibroblasts were grown on cell culture plates and were placed in contact with various concentrations of test irrigants and medications. The cytotoxicity of these materials was evaluated 24 h after incubation using MTT assay. Means and standard deviations of absorbance were calculated for each group and statistically analyzed to determine presence or absence of significant difference between the means. The 50% inhibitory dose values were calculated, ranked, and statistically analyzed using the sign interval for median. Based on our results it seems that MTAD is less cytotoxic than eugenol, 3% H2O2, Ca(OH)2 paste, 5.25% NaOCl, Peridex, and EDTA and more cytotoxic than 2.63%, 1.31%, and 0.66% NaOCl.