Antibacterial Effect of Yellow He-Ne Laser Irradiation with Crystal Violet Solution on Porphyromonas gingivalis: An Evaluation Using Experimental Rat Model Involving Subcutaneous Abscess

Abstract

A study was conducted to evaluate the antibacterial e#ect of yellow He-Ne laser irradiation with crystal violet solution (CV) on Porphyromonas gingivalis (P.g.). Paper points were soaked with a P.g. suspension (10 9 ml) with 0.8 mg/l CV added, laser-irradiated for 60 s (laser group), and implanted subcutaneously on the back of rats. Three additional groups were studied: CV group: the paper point was soaked with the P.g. suspension plus 0.8 mg/l CV, but laser irradiation was not performed; P.g. group: the paper point was soaked with the P.g. suspension only and laser irradiation was not performed; control group: the paper point was soaked with sterilised isotonic sodium chloride solution and laser irradiation was not performed. Seven days after implantation, block sections of all implanted sites were examined histologically. The abscess area in the laser group was smaller than in the P.g. group or CV group, but larger than in the control group. The number of inflammatory cells was greatest in the P.g. and CV groups, with fewer in the laser group and still fewer in the control group. The results indicate that a yellow He-Ne laser with 0.8 mg/l CV solution exerts an antibacterial e#ect in vivo.

Analysis of low level laser therapy in vitro cultures of bacteria and fungi

“…(9,13) Other research on the laser radiation effect on bacteria and fungi point to biostimulants or proliferative results, postulating that these effects are linked to changes generated by increased energy intake provided by the radiation in the respiratory chain of bactéria. (10,14) However, the exact biophysical mechanisms of radiation of low intensity laser on bacterial and fungal cells have been poorly investigated, making controversial the use in suspected contamination or confirmed cases of injury to soft tissue. (15,16) Moreover, Nussbaum et al (15) and Tiphlova, Karu (17) proposed that the photobiological response of an organism to exposure to monochromatic light depends directly on irradiation parameters (wavelength, intensity and dose) and culture conditions germ.…”

“…(9) Although some studies show the bactericidal and / or bacteriostatic laser effect, there is still the paradox of studies that have found increased bacterial growth (especially Escherichia coli) and there are few studies showing the fungicidal effect of the laser. (8,10) The fact is that the increasing resistance of bacteria and fungi to the antifungal and antibiotic drugs makes it necessary to develop new bacteriostatics, bactericides and fungicides methods to cooperate with the treatment of infected individuals.…”

Effects of low intensity laser in in vitro bacterial culture and in vivo infected wounds

“…By the findings from previous studies, the effectiveness of LLLT on tissue repair was observed in various protocols [4][5][6][7][8][9]18 . So far, nonetheless, no work has validated the use of laser therapy when there is the presence of bacterial infection in the wound.…”

“…In some countries this therapy is still viewed with some skepticism due to the publication of controversial articles, showing both beneficial and no effects [9][10][11][12] .…”

O efeito do laser de baixa energia no crescimento bacteriano "in vitro"

“…A aplicação do LBE no processo de cicatrização de feridas parece ser interessante e promissor; entretanto, seu uso no manejo de extensas lesões de tecidos moles com imputada contaminação bacteriana não foi, ainda, objeto de investigação adequada. A influência do LBE sobre a modulação fenotí-pica de diferentes populações bacterianas tem sido pobremente discutida na literatura, em geral utilizando modelos in vitro e experimentações clínicas em odontologia e dermatologia (8)(9)(10)(11)(12)(13) . Nussbaum et al observaram crescimento in vitro de bactérias expostas à irradiação com LBE de 810nm de comprimento de onda e freqüência de 1.000Hz (11) .…”