Cytotoxic Effects of Synthetic and Herbal Endodontic Irrigants on Human Red Blood Cells: An In Vitro Study

Endodontic irrigants are vital for disinfecting root canals; however, their potential to harm healthy cells drives the search for safer options. Herbal extracts may offer natural antimicrobial benefits with reduced toxicity compared with synthetic agents. This study aimed to evaluate the cytotoxicity of synthetic irrigants (5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX)) versus herbal options (neem and garlic extracts) on human red blood cells (RBCs) in vitro. The objectives of this study were to assess RBC viability across different concentrations to identify the least cytotoxic irrigant and evaluate neem and garlic extracts as biocompatible alternatives for endodontic therapy.

This in vitro study was conducted at the Department of Conservative Dentistry and Endodontics, Kalka Dental College, Meerut, India. The study involved collecting 5 mL of venous blood from a healthy volunteer, followed by centrifugation at 1000 rpm for 10 minutes to isolate packed human RBCs. RBCs were washed with 0.9% saline and diluted to create a suspension, with 100 µL aliquoted into 164 test tubes per trial. Four experimental groups (5.25% NaOCl, 2% CHX, neem extract, and garlic extract) each had 40 tubes subdivided by irrigant volume (10-50 µL), and a saline control group had four tubes. Neem extract was prepared by boiling fresh leaves to a 25% concentration, whereas garlic extract was subjected to ethanol treatment and homogenization to 25%. After adding irrigants and incubating for three minutes, RBC viability was measured using an automated hematology analyzer. The experiment was repeated eight times to ensure reliability. Data were statistically analyzed. The tests used were the intraclass correlation (ICC) test and the Kruskal-Wallis test with Bonferroni post-hoc tests, with significance at p < 0.05.

All groups showed significant ICC (p < 0.05), with NaOCl at 0.99 and neem at 0.58. Intergroup analysis revealed the lowest RBC viability for NaOCl (median = 3.26%), while neem (4.91%) and control (5.53%) showed the highest viability. Post-hoc tests confirmed the inferior performance of NaOCl (p < 0.01 vs. all). Concentration-dependent declines were significant across the groups (p < 0.001), with NaOCl showing the steepest drop. Within the concentrations, neem consistently outperformed the others.

Neem extract demonstrated superior biocompatibility as an endodontic irrigant, suggesting its potential as a safer alternative to synthetic agents, such as NaOCl.