Evaluation of cytotoxicity of MTA employing various additives

Objective. Various additives have been suggested to be used with MTA to improve its handling characteristics. The objective of this study was to evaluate the effects of various additives on cytotoxicity of MTA. Study design. Freshly mixed or set MTA pellet (1-mm diameter and 1-mm high cylinder) was prepared by mixing MTA with various additives. Additives tested included water, saline, 2% lidocaine, 5% CaCl2, 3% NaOCl gel, and K-Y liquid. L929 cells were seeded into 96-well plates at 3 x 10(4) cells per well and incubated with MTA pellets for 24 hours, 48 hours, and 72 hours. Cells without treatment served as a control group. Cell viability was evaluated by MTT assay and calculated as the percentage of the control group. The results were analyzed with 1-way ANOVA. Results. For the set MTA, there were no significant cell viability differences (P > .05) among the various additives at each tested time. For the freshly mixed MTA, 3% NaOCl gel has lower cell viability (P < .05) than all the other groups. The cell viability of 3% NaOCl gel group was 29% to 50%. Gray and white MTA have similar results. Conclusion. This study shows that the various additives have no effect on the cytotoxicity of MTA when it becomes set. Also, all the tested additives, except 3% NaOCl gel, had no effect on the cytotoxicity of MTA when it was freshly mixed. The cytotoxicity of 3% NaOCl gel probably has no clinical significance considering there is still 29% to 50% of cell viability after cells were treated with MTA pellet in a 0.32-cm(2) culture well. MTA is biocompatible when mixed with the various additives. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: 739-744)