Periopathogens differ in terms of the susceptibility to toluidine blue O-mediated photodynamic inactivation

Background: The main goal of periodontal therapy is to eliminate the infection spreading in periodontium. Antimicrobial photodynamic therapy may be applied in order to eradicate pathogens remaining in periodontal tissues after conventional mechanical debridement, to improve the treatment results. The aim of this in vitro study was to evaluate the susceptibility of selected key periopathogens to toluidine blue O-mediated photo dynamic inactivation and the influence of photosensitizer's concentration and light dose on the effectiveness of this process. Methods: Following bacterial strains were used in the experiments: Porphyromonas gingivalis ATCC 33277, Aggregatibacter actinomyctemecomitans ATCC 33384, Fusobacterium nucleatum ATCC 10953. Toluidine blue O (TBO) was used in concentration ranging from 0.004 to 0.5 mg/mL. Irradiation was performed by a non-laser red light source. Results: Complete eradication of P. gingivalis was obtained upon the application of TBO in the concentration of 0.1 mg/mL and the highest light dose. A, actinomycetemcomitans was, in turn, not susceptible to photodynamic inactivation regardless of the dosimetric parameters applied. High viability reductions were also obtained for F. nucleatum, however no complete eradication. The effectiveness of photodynamic inactivation of susceptible periopathogens was dependent on the light dose and photosensitizer's concentration. Conclusions: Periopathogens differ in terms of their susceptibility to photodynamic inactivation. Antimicrobial PDT may be valuable in the treatment of those cases of periodontal disease, in which P. gingivalis is a dominating pathogen. Microbiological examination prior to clinical application of aPDT may be recommended.