Cytotoxicity Evaluation of Combination Irrigant Regimens with MTAD on Two Different Cell Lines

BACKGROUND: Effective management of smear layer ensures adequate clinical success. Use of sodium hypochlorite (NaOCl)/ethylenediaminetetraacetic acid regimen has been the gold standard with limitations. Commercial irrigants incorporate surface modifiers to address these drawbacks. The aim of this study was to evaluate the cytotoxicity of combination regimens on target and nontarget cell lines by trypan blue assay. MATERIALS AND METHODS: Nonsurfactant combination regimen of chlorhexidine (CHX) and NaOCl (2% CHX + 2.5% NaOCl) and surfactant regimens of CHX with cetrimide (CTR) (2% CHX + 0.5% CTR) and CHX with sodium dodecyl sulfate (2% CHX + 1% SDS) were prepared. 0.9% normal saline (NS) and Biopure MTAD (100%) served as control. Cytotoxicity was evaluated on human gingival fibroblast (HGF) and Henrietta Lacks (HeLa) cell lines by trypan blue assay. Thirty microliter of the cell suspension was treated with 20 μl 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: Nonsurfactant combination comprising of 2% CHX + 2.5% NaOCl formed a brownish precipitate while surfactant combination regimes were stable without any precipitate formation. NS and 2% CHX + 0.5% CTR had greater viability scores on both cell lines. Two percent CHX + 1% SDS had better viability on HeLa but were severely cytotoxic on HGF. Two percent CHX + 2.5% NaOCl and MTAD were found to be severely cytotoxic on HeLa with limited viability on HGF. CONCLUSION: The variation in data obtained could be possibly attributed to the difference in the cellular membrane composition and mechanism of action of combination regimens. Experimental surfactant regimen 2% CHX + 0.5% CTR shows lower cytotoxicity than MTAD.