Abstract
Background: Irrigants plays a vital role in disinfection of the root canal system. Although concentration dependent, a fine balance between antimicrobial efficacy and biocompatibility need to be maintained at all times. The aim of the present study was to evaluate the cytotoxicity of conventional irrigants on two different cell lines in a dose-dependent manner in vitro. Methods: Sodium hypochlorite (NaOCl), chlorhexidine digluconate (CHX), and iodine potassium iodide (IKI) were prepared in concentrations of 5%, 2.5%, 2%, and 1%. About 0.9% saline served as negative control and Biopure MTADTM (100%) as positive control. Permanent (Henrietta Lacks [HeLa]) and primary (human gingival fibroblast [HGF]) cell lines were chosen to evaluate the cytotoxicity of the irrigants by trypan blue assay. A volume of 30 mu l of the cell suspension was treated with 20 mu l of irrigants. The cell suspension was loaded into Neubauer chamber after 5 min, and cell count was performed under inverted microscope and expressed as viability percentage. Results: NaOCl at all concentrations was cytotoxic on both cell lines; MTAD on HeLa had nonviable scores with limited viability on HGF. Only 1% IKI had better viability than higher concentrations. Although 1% CHX had higher viability on both cell lines, bactericidal concentration of 2% CHX showed promising results. Conclusion: Target cell line (HGF) appears to be more sensitive than the use of nontarget cell line (HeLa) for evaluating cytotoxicity. NaOCl and MTAD were cytotoxic and should be used with caution. Lower concentrations of CHX appear to be less cytotoxic than any irrigant and concentrations tested.