Henninger, EvaEvaHenningerAranha Berto, LucianaLucianaAranha BertoEick, SigrunSigrunEickLussi, AdrianAdrianLussiNeuhaus, KlausKlausNeuhaus0000-0002-4686-13622024-10-282024-10-282019-06https://boris-portal.unibe.ch/handle/20.500.12422/183639Objective: The purpose of this in vitro study was to evaluate the antimicrobial effect of activated irrigation with different modes of erbium-doped yttrium aluminum garnet (Er:YAG) laser application on microorganisms related to secondary endodontic infection. Background: Er:YAG laser has been recommended as an adjuvant tool for root canal disinfection during endodontic treatment. Materials and methods: Laser-activated irrigation (LAI) with 300 or 600 μm tips were tested with or without intermittent irrigation with 0.9% sodium chloride (NaCl) solution against different microorganisms (five single strains and dual species (Streptococcus gordonii combined with Actinomyces oris or Fusobacterium nucleatum) in root canals after 3 days of incubation. In a 21-day infection model, LAI was used together with intermittent rinsing with sodium hypochlorite (NaOCl) against the dual-species mixtures; here the incidence of microbial regrowth after up to 7 days was monitored. Results: In the 3-day root infection model, LAI protocols did not show any significant reduction of the microbial load when compared with manual irrigation with saline solution. In the 21-day infection, S. gordonii combined with A. oris were not detectable anymore after applying the LAI protocol with a 600 μm tip (30 mJ/10 pps) up to 7 days after treatment. Conclusions: Application of LAI with a 600 μm tip by using an Er:YAG laser might be advantageous in treatment of endodontic infections.encavitation disinfection endodontics irrigation600 - Technology::610 - Medicine & healtharticle10.7892/boris.1355413107469310.1089/photob.2018.4557