Impact of N-acetylcysteine (NAC) and calcium hydroxide intracanal medications in primary endodontic infection: a randomized clinical trial

Objectives This RCT investigated the impact of N-acetylcysteine (NAC) and calcium hydroxide [Ca(OH)(2)] intracanal medications (ICMs) in primary endodontic infection with apical periodontitis (PEIAP). Materials and methods Thirty-six teeth with PEIAP were randomly divided into groups according to the ICM: NAC, Ca(OH)(2) + saline solution (SSL), and Ca(OH)(2) + 2% chlorhexidine-gel (2% CHX-gel) (all, n= 12). Root canal samples (RCSs) were collected before (s1) and after instrumentation (s2) and after 14 days of ICM (s3). Chemomechanical preparation (CMP) was performed with a Reciproc file and 2.5% NaOCl. Checkerboard DNA-DNA hybridization was used to assess 40 target bacteria species. Results At s1, bacterial DNA was detected in 100% of RCSs (36/36). All 40 bacterial species were found in PEIAP. The mean number of species per RCS was 17.92 +/- 13.18. The most frequent bacteria were S. mitis (65%), E. nodatum (63%), E. faecalis (63%), F. nucl sp vicentii (58%), T. forsythia (58%), and F. periodonticum (56%). CMP reduced the mean number of species per RCS to 6.8 +/- 2.36 (p < 0.05). At s3, the intragroup analysis revealed a broader antimicrobial activity for Ca (OH)(2) + 2% CHX-gel and NAC than Ca(OH)(2) + SSL (p < 0.05). NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs, including P. micra, P. nigrescens, T. denticola, A. israelii, P. endodontalis, P. acnes, C. ochracea, and E. corrodens. Conclusions Ca (OH)2 + 2% chlorhexidine gel (2% CHX gel) showed a greater bacterial elimination over the number of bacterial species; however, NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs (RBR-3xbnnn).