RESUMEN
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.
Asunto(s)
Infecciones Bacterianas/tratamiento farmacológico , Enfermedades de la Pulpa Dental/microbiología , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/uso terapéutico , Biopelículas/efectos de los fármacos , Recuento de Colonia Microbiana , Cavidad Pulpar/efectos de los fármacos , Cavidad Pulpar/microbiología , Enfermedades de la Pulpa Dental/tratamiento farmacológico , Desinfección/métodos , Enterococcus faecalis/efectos de los fármacos , Fusobacterium nucleatum/efectos de los fármacos , Humanos , Terapia por Láser , Azul de Metileno/uso terapéutico , Microscopía Electrónica de Rastreo , Peptostreptococcus/efectos de los fármacos , Fotoquimioterapia/instrumentación , Porphyromonas endodontalis/efectos de los fármacos , Porphyromonas gingivalis/efectos de los fármacos , Prevotella intermedia/efectos de los fármacosRESUMEN
We have found that broadband light (380 to 520 nm) rapidly and selectively kills oral black-pigmented bacteria (BPB) in pure cultures and in dental plaque samples obtained from human subjects with chronic periodontitis. We hypothesize that this killing effect is a result of light excitation of their endogenous porphyrins. Cultures of Prevotella intermedia and P. nigrescens were killed by 4.2 J/cm2, whereas P. melaninogenica required 21 J/cm2. Exposure to light with a fluence of 42 J/cm2 produced 99% killing of P. gingivalis. High-performance liquid chromatography demonstrated the presence of various amounts of different porphyrin molecules in BPB. The amounts of endogenous porphyrin in BPB were 267 (P. intermedia), 47 (P. nigrescens), 41 (P. melaninogenica), and 2.2 (P. gingivalis) ng/mg. Analysis of bacteria in dental plaque samples by DNA-DNA hybridization for 40 taxa before and after phototherapy showed that the growth of the four BPB was decreased by 2 and 3 times after irradiation at energy fluences of 4.2 and 21 J/cm2, respectively, whereas the growth of the remaining 36 microorganisms was decreased by 1.5 times at both energy fluences. The present study suggests that intraoral light exposure may be used to control BPB growth and possibly benefit patients with periodontal disease.