Methods: In this in vitro study, cytotoxicity was evaluated by fibroblast cell culture and its direct contact with the test materials. Cell survival fraction was estimated by MTT test after 1, 12, 24, 48, and 72 h. The corresponding data were analyzed statistically using One way ANOVA test.
Results: By gradually increasing concentrations and time, an increased cytotoxicity was observed for each agent. 2% chlorhexidine gel had the highest toxicity in all concentrations and time durations, while calcium hydroxide had the least. After 1 hour, calcium hydroxide had the lowest cytotoxicity. However, no significant differences were observed between the three other agents (P>0.05). The same trend was observed in other time durations.
Conclusions: Calcium hydroxide is the least toxic intracanal medicament. Agents containing chlorhexidine should be used with caution in tooth canals due to their great potency of cytotoxicity. Calcium hydroxide reinforced with chlorhexidine with less cytotoxicity than chlorhexidine can be used as dressing between endodontic sessions with caution.