Esper, Maria Ângela Lacerda Rangel [UNESP]Barbosa, Júnia Oliveira [UNESP]Alvarenga, Janaína Araújo De [UNESP]Junqueira, Juliana Campos [UNESP]Rastelli, Alessandra Nara De Souza [UNESP]Gonçalves, Sérgio Eduardo De Paiva [UNESP]2020-12-122020-12-122020-04-01Brazilian Dental Science, v. 23, n. 2, 2020.2178-6011http://hdl.handle.net/11449/200344Objective: The aim of this in vitro study was to evaluate the efficacy of photodynamic inactivation (PDI) with erythrosine (E), using a light-emitting diode (LED) on planktonic cultures of Streptococcus mutans. Material and Methods: A Streptococcus mutans strain (UA 159) was used to prepare the suspensions containing 107 cells/mL, which was tested under different experimental conditions: a) LED irradiation in the presence of erythrosine as a photosensitizer (E+L+); b) LED irradiation only (P-L+); c) treatment with erythrosine only (E+L-); and d) no LED irradiation or photosensitizer (P) treatment, which served as a control group (P-L-). After treatment, strains were seeded onto MSBS agar for determination of the number of colony-forming units (CFU/mL). Results: The results were submitted to analysis of variance and the Tukey test (p < 0.05). No reduction in the number of CFU/mL was observed in the treatment group with erythrosine (E+L+) when compared to the control (P-L-). Conclusion: PDI using erythrosine did not reduce the number of CFUs per millimeter within the parameters in this study.engDecayErythrosineLight-emitting diodePhotodynamic inactivationArtigo10.14295/bds.2020.v23i2.18572-s2.0-85084007823