title: The antimicrobial activity of photodynamic therapy against Streptococcus mutans using different photosensitizers.
abstract: Several photosensitizers have been used against oral bacteria without standardization. Singlet oxygen ((1)O(2)) is an aggressive chemical species that can kill cells through apoptosis or necrosis.
  
  
  OBJECTIVE
  to compare the antimicrobial activity of photodynamic therapy (PDT) with different photosensitizers at the same concentration against Streptococcus mutans. In addition, the (1)O(2) production of each photosensitizer was determined. The photosensitizers (163.5 μM) methylene blue (MB), toluidine blue ortho (TBO) and malachite green (MG) were activated with a light-emitting diode (LED; λ=636 nm), while eosin (EOS), erythrosine (ERI) and rose bengal (RB) were irradiated with a curing light (λ=570 nm). Light sources were operated at 24 J cm(-2). For each photosensitizer, 40 randomized assays (n=10 per condition) were performed under one of the following experimental conditions: no light irradiation or photosensitizer, irradiation only, photosensitizer only or irradiation in the presence of a photosensitizer. After treatment, serial dilutions of S. mutans were seeded onto brain heart infusion agar to determine viability in colony-forming units per milliliter (CFU mL(-1)). Generation of (1)O(2) was analyzed by tryptophan photooxidation, and the decay constant was estimated. Results were analyzed by one-way ANOVA and the Tukey-Kramer test (p<0.05). PDT with irradiation in the presence of the photosensitizers TBO and MG was effective in reducing S. mutans counts by 3 and 1.4 logs, respectively (p<0.01), compared to their respective untreated controls. MB generated 1.3 times more (1)O(2) than TBO, and both produced significantly higher concentrations of singlet oxygen than the other photosensitizers. Since in vitro bulk (1)O(2) production does not indicate that (1)O(2) was generated in the bacterial activity site, the bactericidal action against S. mutans cannot be related to in vitro singlet O(2) generation rate. In vitroS. mutans-experiments demonstrated TBO as the only photosensitizer that effectively reduced 99.9% of these microorganisms.
authors: Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará, Department of Operative Dentistry, Rua Cap. Francisco Pedro, S/N, Rodolfo Teófilo, 60430-170 Fortaleza, CE, Brazil.
authors: Juliana P M L
authors: JP
authors: Rolim
authors: Mary A S
authors: MA
authors: de-Melo
authors: Sarah F
authors: SF
authors: Guedes
authors: Fernando B
authors: FB
authors: Albuquerque-Filho
authors: Jackson R
authors: JR
authors: de Souza
authors: Nádia A P
authors: NA
authors: Nogueira
authors: Iriana C J
authors: IC
authors: Zanin
authors: Lidiany K A
authors: LK
authors: Rodrigues
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D004801:Eosine Yellowish-(YS) / Q000737:chemistry; D004923:Erythrosine / Q000737:chemistry; D008027:Light; D008751:Methylene Blue / Q000737:chemistry / Q000494:pharmacology; D010084:Oxidation-Reduction; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D012394:Rosaniline Dyes / Q000737:chemistry / Q000494:pharmacology; D012395:Rose Bengal / Q000737:chemistry; D026082:Singlet Oxygen / Q000378:metabolism; D013295:Streptococcus mutans / Q000187:drug effects* / Q000528:radiation effects; D014048:Tolonium Chloride / Q000737:chemistry / Q000494:pharmacology; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D017319:Photosensitizing Agents; D012394:Rosaniline Dyes; C005095:malachite green; D014048:Tolonium Chloride; D026082:Singlet Oxygen; D012395:Rose Bengal; D014364:Tryptophan; D004923:Erythrosine; D008751:Methylene Blue; D004801:Eosine Yellowish-(YS)