RESUMEN
OBJECTIVE: The purpose of this systematic review was to provide the answer to the question: Can sodium hypochlorite and chlorhexidine influence postoperative pain after the endodontic treatment in necrotic teeth? METHODS: The PROSPERO registration number is CRD42018096433 and was conducted following the PRISMA statements. The MeSH and free terms were used to search for articles published in the electronic databases (PubMed, Web of Science, Scopus, Cochrane Library, and Virtual Health Library), in the gray literature, and by a manual search. The reviewers selected the studies considering predetermined eligibility criteria, performed data extraction, and evaluated the risk of bias. Only clinical trials comparing the effect of sodium hypochlorite and chlorhexidine on postoperative pain in teeth of adult patients with necrotic pulps were included. RESULTS: Five studies were qualified for the systematic review. Two studies were considered a low risk of bias. The results showed no statistically significant difference regarding postoperative pain in the groups. Only 1 study reported a statistically significant difference in the sixth postoperative hour, and the pain was associated with the sodium hypochlorite group. CONCLUSION: There was no influence of auxiliary chemical substance (NaOCl and CHX) on postoperative pain used in endodontic treatment in the teeth with pulp necrosis. However, one study observed a significant difference in the sixth postoperative hour, associated with the sodium hypochlorite group.