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).
Clinical Relevance: The use of intracanal medication with a broad antimicrobial activity can optimize root canal disinfection. Ca(OH) ₂  + 2% CHX gel and NAC showed a broader antimicrobial activity than Ca(OH) ₂  + SSL against endodontic pathogens in primary root canal infection.
Trial Registration: Brazilian Registry of Clinical Trials (REBEC), No. RBR-3xbnnn.
(© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)