Cytotoxic effects of various root canal irrigants on L929 cells

Objective: Irrigants are essential in endodontic therapy to facilitate instrumentation, removal of organic and inorganic debris, and elimination of microorganisms. Therefore, an ideal irrigant should not only be an efficient antimicrobial agent, but also non-toxic to periodontal tissues. The purpose of this study was to assess in vitro cytotoxicity of different irrigants (BioPure MTAD-Dentsply/USA, Tubulicid Plus-Dental Therapeutics/Sweden, Cetrexidin-Vebas/Italy, 15 % EDTA and 1, 2, 4 % concentrations of buffered or un-buffered NaOCl) using a mouse fibroblast cell line (L929).

Methods: The various irrigants were diluted in minimal essential culture medium (MEM). L929 cells were seeded in 96-well plates (1.5x10⁴cells/well) for 24 h in normal culture medium. Then, cells were exposed to the various diluted irrigants for either 10 min or 1 hour. As control, cells were grown in normal culture medium. Diphenyltetrazolium bromide (MTT) and WST-1 proliferation assays were used to evaluate cell viability. Morphology of cells was examined under a light microscope. Statistical significant differences between the groups were analyzed by a one-way analysis of variance and a multiple comparison tests (P<0.05).

Results: MTT and WST-1 assays demonstrated that un-buffered 2 and 4 % NaOCl solutions, 4 % buffered NaOCl, Tubilicid Plus and Cetrexidin solutions were cytotoxic to cells after 10 min or 1 hour exposure. Diluted concentrations of Un-buffered 1 % NaOCl solution, buffered 1 and 2 % NaOCl solutions, BioPure MTAD and 15% EDTA solutions had no toxic effect and demonstrated similar cell viability to that of control cells.

Conclusion: This in vitro study suggests that some irrigants may cause detrimental effects on the periodontal cells. The clinical relevance needs to be evaluated further, as the effect might differ according to concentration of solutions, exposure surface and contact time.

Acknowledgements: Authors would like to thank Dentsply Company and Dental Therapeutics for material support for this study.