Ponpen TantivitayakulSupanee RassameemasmaungSununtha ThapanabhiboonsukMahidol University2019-08-232019-08-232018-10-01European Journal of Dentistry. Vol.12, No.4 (2018), 485-49013057464130574562-s2.0-85054503953https://repository.li.mahidol.ac.th/handle/20.500.14594/45696© 2018 European Journal of Dentistry | Published by Wolters Kluwer - Medknow. Objective: The main objective is to investigate the antibacterial effect of diode laser against Aggregatibacter actinomycetemcomitans biofilm. Materials and Methods: Biofilms of A. actinomycetemcomitans plus Streptococcus sanguinis grown on bovine root surfaces were treated with an 810-nm diode laser using a noncontact pulsed mode with a pulse interval and pulse length of 20 ms. Four protocols, that is, one episode of 1.5 or 2.5 W for 30 s and three episodes of 1.5 or 2.5 W for 30 s were tested. No treatment and 0.2% chlorhexidine treatment served as negative and positive controls, respectively. Viable bacterial number was determined by colony counting. Results: Treatment with chlorhexidine and all laser protocols except that using single episode of 1.5 W reduced the number of A. actinomycetemcomitans in either single-species or dual-species biofilm compared to negative control. A higher percentage of A. actinomycetemcomitans reduction was demonstrated after increasing the power output or repeating the irradiation. Conclusions: The laser protocols used in this study could reduce the number of viable bacteria but not eradicate A. actinomycetemcomitans biofilm.Mahidol UniversityDentistryArticleSCOPUS10.4103/ejd.ejd_289_17