N-acetyl cysteine as an adjuvant medication for regenerative endodontics.

OBJECTIVE: To perform an in vitro evaluation of the effects of N-acetyl cysteine (NAC) on the viability and osteogenic expression of dental pulp stem cells (DPSC), as well as its mechanical removability from root canals. METHODS: DPSC were exposed to NAC at concentrations of 0.01, 0.1, and 1 mg/mL under stabilized and non-stabilized pH conditions for 24 or 48 hours. Cell viability was assessed using the sulforhodamine-B (SRB) assay. Osteocalcin (OCN) expression, with or without induction of oxidative stress (H2O2), was quantified by ELISA. NAC removal was evaluated in bovine teeth by scanning electron microscopy (SEM) after using three irrigation techniques: conventional irrigation (CI), EasyClean (EC), and passive ultrasonic irrigation (PUI). Data was analyzed by two-way ANOVA (p<0.05). RESULTS: After 24 hours, NAC did not show cytotoxic effects at any concentration or pH condition. At 48 hours, a significant reduction in viability was observed at 0.1 and 1 mg/mL NAC (p<0.05), while 0.01 mg/mL NAC maintained viability similar to the control. OCN was expressed in all groups but statistically reduced in the presence of Reactive Oxygen Species (ROS). SEM analysis showed no statistical differences between the groups or among root thirds (p>0.05). CONCLUSION: NAC showed low cytotoxicity at short exposure times, especially at 0.01 mg/mL, and recovery of OCN expression. Its removal was feasible regardless of the irrigation technique or root third evaluated. The results provide relevant evidence regarding the safety, cellular behavior, and removal of NAC from the canal walls.