Agradecimentos: We are thankful to Mr. Maicon R. Z. Passini from the Piracicaba Dental School, State University of Campinas (UNICAMP), for his technical support. This work was supported by the following Brazilian agencies: São Paulo Research Foundation (FAPESP grant numbers 15/23419-5, 17/25090-3 and 2021/13871-6), National Council for Scientific and Technological Development (CNPq grant numbers 303852/2019-4, 100453/2018-0, 102276/2019-6 and 421801/2021-2) and Coordination for the Improvement of Higher Education Personnel (CAPES, finance code 001) Ver menos

Abstract: This in vitro study aimed to verify the influence of chlorhexidine (CHX) (gel and solution) in association with different activation protocols on disinfection of root canals contaminated with Enterococcus faecalis. In total, 120 lower premolar roots were selected, contaminated and divided into 12 groups according to irrigation technique and substance. Samples were collected before and after each irrigation technique and analysed for colony-forming units (CFU). Three dentin discs were obtained for quantification of viable intratubular cells by using confocal laser scanning microscopy (CLSM). CFU results showed that sonic and ultrasonic were more effective than conventional irrigation. Ultrasonic activation was more effective than sonic for CHX gel (p < 0.05). CLSM showed that either activation was better than conventional in all groups and root canal thirds (p < 0.05). It was concluded that ultrasonic/sonic activation was more effective than conventional techniques and CHX enhanced intratubular dentin decontamination across all irrigation methods Ver menos