Comparative Evaluation of Cytotoxicity of Neem Leaf Extract, 2% Chlorhexidine, Nigella sativa Extract and 3% Sodium Hypochlorite

Abstract

To assess and compare the cytotoxicity of different root canal irrigants, namely 25% aqueous neem leaf extract (Azadirachta indica), 2% chlorhexidine (CHX), 25% aqueous Nigella sativa extract (black seed) and 3% sodium hypochlorite (NaOCl). Dulbecco modified Eagle’s medium containing glutamine, fetal bovine serum, and antibiotics were used to culture human periodontal ligament cells. After trypsinization, 1 × 105 cell suspension was seeded in 24 well culture plates with 100 µL of culture medium. Then 10 µl of each irrigant was added to the wells, sealed, and incubated in an oven at 37°C in an atmosphere of 5% CO2 and 95% humidity. Cytotoxicity was assessed at 1, 3, 6, and 24 hours by evaluating the cell viability using the trypan blue assay. A microscope was used for counting viable cells and subjected to statistical analysis. 25% aqueous Neem leaf extract was the most cytotoxic irrigant tested, followed by 2% CHX, while 25% aqueous N. sativa extract was the least cytotoxic irrigant tested. 25% aqueous N. sativa extract and 3% NaOCl solutions were significantly less toxic than 25% aqueous Neem leaf extract solution and cytotoxicity of 2% chlorhexidine was significantly more than 25% aqueous N. sativa extract and 3% NaOCl at all periods. Considering this encouraging in vitro data, herbal extracts could be an alternative root canal irrigant with the most negligible toxicity compared to conventional root canal irrigants, with undesirable effects.