Cytotoxicity evaluation of calcium hypochlorite and other commonly used root canal irrigants against human gingival fibroblast cells: An in vitro evaluation

Abstract

Background. The conventional endodontic therapy primarily focuses on biomechanical preparation, which is achieved by the application of various intracanal irrigants and intracanal medicaments. One of the most commonly used intracanal irrigants – sodium hypochlorite (NaOCl) – has already been proven to have an antimicrobial effect as well as the ability to dissolve tissues in the areas where files cannot reach. One of the recently used irrigants having a promising effect is calcium hypochlorite (Ca(OCl)2), which has been shown to be relatively more stable than NaOCl and has much more chlorine ions. Objectives. The aim of this study was to assess the individual cytotoxicity of various root canal irrigants and the combined cytotoxicity of NaOCl and Ca(OCl)2 with ethylenediaminetetraacetic acid (EDTA) against human gingival fibroblast (hGF) cells. Material and methods. The evaluation of the individual cytotoxicity was carried out with regard to the following root canal irrigants: NaOCl; Ca(OCl)2; and chlorhexidine (CHX). The evaluation of the combined cytotoxicity regarded NaOCl/EDTA and Ca(OCl)2/EDTA. The concentrations used were 0.025%, 0.050%, 0.10%, and 0.20%. The cytotoxicity against hGF cells was examined within a timeframe of 6 h and 24 h with the use of the sulforhodamine B (SRB) assay. Results. It was observed that Ca(OCl)2 had a mean absorbance rate of 0.315 ±0.02, 0.294 ±0.03, 0.265 ±0.03, and 0.240 ±0.02 at 0.025%, 0.050%, 0.10%, and 0.20%, respectively. In combination with EDTA, the mean absorbance rate was 70.12 ±2.9, 67.42 ±4.3, 64.35 ±3.6, and 61.58 ±4.1 at 0.025%, 0.050%, 0.10%, and 0.20%, respectively. The cytotoxic effect of the root canal irrigants on hGF cells was observed to be statistically significant (p < 0.05). Conclusions. Calcium hypochlorite is less cytotoxic than NaOCl, and when used in combination with EDTA, it was shown to have its cytotoxic effect on hGF cells reduced to a great extent.