Photoinactivation of F. nucleatum and P. gingivalis using the ruthenium-based RD3 sensitizer and a conventional halogen lamp.

OBJECTIVE: The photodynamic therapy (PDT) is an alternative method to suppress oral pathogens by the activation of a photosensitizer with laser light. The aim of this study was to investigate the phototoxic effect of three ruthenium-based photosensitizers on Fusobacterium nucleatum and Porphyromonas gingivalis. METHODS: In this in vitro study F. nucleatum and P. gingivalis were incubated with three photosensitizers: (i) a hydrophobic tris-(4,7-diphenyl-1,10-phenanthroline)-ruthenium(II)-dication (RD3), (ii) a hydrophilic tris-[(1,10-phenanthroline-4,7-diyl)-bis-(benzenesulfonato)]-ruthenate tetra-anion (RSD3) and (iii) a lower hydrophilic tris-(2,2'-bipyridine)-ruthenium(II) dication (RBY). The subsequent irradiation was done with blue-band halogen light (450-485nm) for 20s using a conventional polymerizer. Control samples consisted of bacterial cell suspension irradiated and non-irradiated in the absence of photosensitizer or incubated with the photosensitizer without irradiation. Bacterial inactivation was determined by the numbers of colony-forming units (cfu/ml) after anaerobic cultivation. RESULTS: The RD3 photosensitizer reduced the viability of F. nucleatum by 4-log10 and of P. gingivalis completely after irradiation for 20s. The viability loss correlated significantly with the concentration of the RD3 photosensitizer and reached a peak at a concentration of 12.5µM (p<0.05). The RSD3 and RBY photosensitizers had distinctly lower phototoxic effects in comparison to RD3. CONCLUSION: The RD3 photosensitizer showed a phototoxic effect on F. nucleatum and P. gingivalis. The results suggest that the application of the RD3 photosensitizer under visible light may be helpful as an adjunct treatment approach to the inactivation of periodontopathogenic bacteria.

Combination of 10% EDTA, Photosan, and a blue light hand-held photopolymerizer to inactivate leading oral bacteria in dentistry in vitro.

AIMS: The goal of this study was to investigate the phototoxicity of Photosan in combination with EDTA and a hand-held photopolymerizer used in dentistry for light-curing resins against leading key pathogens in caries, endodontic treatment failures, and periodontitis respectively. METHODS AND RESULTS: Cellular uptake of Photosan was detected by fluorescence spectroscopy for Streptococcus mutans and Enterococcus faecalis but not for Aggregatibacter actinomycetemcomitans. Addition of 10% EDTA enabled the uptake of Photosan by A. actinomycetemcomitans. Killing of S. mutans and E. faecalis mediated by Photosan and blue light was concentration and light dose dependent, achieving a >or=99.9% (>or=3 log(10) reduction) efficacy of bacteria killing. In the presence of 10% EDTA, Photosan induced a reduction of >or=4 log(10) in the viability of A. actinomycetemcomitans at a concentration of 50 microg ml(-1), upon activation at a dose of 9.65 J cm(-2) for 60 s. EDTA alone, light alone, and Photosan alone were not able to kill bacteria. CONCLUSIONS: Ten per cent EDTA and Photosan cause a potent phototoxicity against oral bacteria upon illumination with a photopolymerizer. SIGNIFICANCE AND IMPACT OF THE STUDY: Increasing antibiotic resistance and insufficient drug concentrations within the sulcus fluid are responsible for lacking antimicrobial efficacy. This study provides useful information that combination of Photosan, EDTA, and a photopolymerizer may be a potentially powerful tool for the efficient destroying of key oral bacteria.