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The aims of this study were to investigate the effects of photodynamic therapy (PDT) on endodontic pathogens in planktonic phase as well as on Enterococcus faecalis biofilms in experimentally infected root canals of extracted teeth. Strains of microorganisms were sensitized with methylene blue (25 microg/ml) for 5 minutes followed by exposure to red light of 665 nm with an energy fluence of 30 J/cm2. Methylene blue fully eliminated all bacterial species with the exception of E. faecalis (53% killing). The same concentration of methylene blue in combination with red light (222 J/cm2) was able to eliminate 97% of E. faecalis biofilm bacteria in root canals using an optical fiber with multiple cylindrical diffusers that uniformly distributed light at 360 degrees. We conclude that PDT may be developed as an adjunctive procedure to kill residual bacteria in the root canal system after standard endodontic treatment.

Abstract: Introduction: T-regulatory (Treg, CD4+ FOXP3+) cells constitute a unique subpopulation of CD4+ T cells that inhibit T-cell responses and prevent disease development/exacerbation in models of autoimmunity. In the present study, we tested the hypothesis that Treg cells are induced in periapical lesions by dental pulp infection. Methods: In situ hybridization (ISH) was used to localize FOXP3+ cells on day 21 after pulp exposure of the first molar teeth and infection with bacteria from the oral environment. FOXP3/GFP knock-in transgenic mice were used to quantify FOXP3+ Treg cells that infiltrate into periapical lesions by flow cytometry on days 7, 14, and 21 after infection. Periodontal ligament from uninfected teeth served as a negative control. Results: ISH showed strong signals that showed the presence of FOXP3+ cells mainly at the periphery of periapical lesions. In contrast, no positive cells were present in the periodontal ligament of uninfected controls. Flow cytometry showed an increase in the number of FOXP3+ Treg beginning between day 7 and day 14 (0.69% of the infiltrate) after infection and increased to day 21 (0.94%) (p < 0.05 and p < 0.001, respectively, vs uninfected controls). Treg were also increased in number in draining cervical lymph nodes after pulpal infection. Conclusions: These results show that Treg cells are induced to infiltrate into periapical lesions by pulpal infection and suggest that they increase in a time-dependent manner. [Copyright &y& Elsevier]

Abstract: We investigated the photodynamic effects of methylene blue on multispecies root canal biofilms comprising Actinomyces israelii, Fusobacterium nucleatum subspecies nucleatum, Porphyromonas gingivalis, and Prevotella intermedia in experimentally infected root canals of extracted human teeth in vitro. The 4 test microorganisms were detected in root canals by using DNA probes. Scanning electron microscopy showed the presence of biofilms in root canals before therapy. Root canal systems were incubated with methylene blue (25 μg/mL) for 10 minutes followed by exposure to red light at 665 nm with an energy fluence of 30 J/cm2. Light was delivered from a diode laser via a 250-μm diameter polymethyl methacrylate optical fiber that uniformly distributed light over 360 degrees. Photodynamic therapy (PDT) achieved up to 80% reduction of colony-forming unit counts. We concluded that PDT can be an effective adjunct to standard endodontic antimicrobial treatment when the PDT parameters are optimized. [Copyright &y& Elsevier]