Antimicrobial efficacy of natural-based endodontic solutions: a systematic review with a network meta-analysis

This systematic review aims to provide preclinical evidence of the antimicrobial efficacy of natural endodontic solutions (NES) compared to sodium hypochlorite (NaOCl) and chlorhexidine (CHX) against Enterococcus faecalis. The study followed the PRISMA guidelines and had a registered protocol (PROSPERO – CRD42021224022). The inclusion criteria comprised ex vivo studies simulating root canal irrigation to assess the standardized mean difference of colony-forming units (CFUs). Records were systematically identified in PubMed, Scopus, EMBASE, SciELO, Web of Science, LILACS, DANS Easy, and BDTD databases in January 2024. The RoBDEMAT tool helped determine the risk of bias. As for the network meta-analysis, CFU data were collected pre- and post-irrigation protocols as an effect measure. Thirty-five studies met the eligibility criteria and were included in the qualitative analysis, and seven studies were eligible for the network meta-analysis. The total sample consisted of 1,504 root canals. Among the tested solutions, apple cider vinegar combined with 2.5% NaOCl showed the highest probability of reducing CFUs after root canal irrigation (95%CI: -0.76–0.20), followed by 2% CHX and NaOCl (considering the different concentrations [95%CI: -0.32–0.17]). The bias assessment revealed significant omissions in reporting, particularly regarding sample size calculation, sample randomization, and operator blinding. The obtained evidence demonstrated that, even though NES did not overcome NaOCl, they have antimicrobial potential against Enterococcus faecalis.