Lethal photosensitization of bacteria in subgingival plaque from patients with chronic periodontitis.
Subgingival plaque samples from patients with chronic periodontitis were exposed to light from a 7.3 mW Helium/Neon laser for 30 s in the presence and absence of 50 micrograms/ml toluidine blue O as a photosensitizer. Viable counts of various groups and species of bacteria were carried out before and after irradiation. The median numbers of viable bacteria initially present in the 30-microliters aliquots irradiated were 1.13 x 10(5) cfu (aerobes), 4.08 x 10(5) cfu (anaerobes), 4.92 x 10(3) cfu (black-pigmented anaerobes), 4.75 x 10(2) cfu (Porphyromonas gingivalis), 6.15 x 10(3) cfu (Fusobacterium nucleatum) and 1.7 x 10(4) cfu (streptococci). The dye/laser combination achieved significant reductions in the viability of these organisms, the median reductions in the viable counts being 91.1% for aerobes, 96.6% for anaerobes, 100% for black-pigmented anaerobes, P. gingivalis and F. nucleatum and 94.2% for streptococci. Overall, the viability of bacteria in the 20 plaque samples was not significantly decreased by the dye alone. However, in a small minority of samples there were indications of light-independent, dye-induced toxicity. Low-power lasers, in conjunction with appropriate photosensitizers, may be a useful adjunct to mechanical debridement in the treatment of inflammatory periodontal diseases if a similar effectiveness against subgingival plaque bacteria can be achieved in vivo.
Department of Microbiology, Institute of Dental Surgery, London, England.
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Sarkar
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Wilson
D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects / Q000528:radiation effects; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000528:radiation effects*; D001421:Bacteria, Anaerobic / Q000187:drug effects / Q000528:radiation effects*; D001587:Benzoylarginine-2-Naphthylamide; D016009:Chi-Square Distribution; D002908:Chronic Disease; D015169:Colony Count, Microbial; D003773:Dental Plaque / Q000382:microbiology*; D005260:Female; D016967:Fusobacterium nucleatum / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D010518:Periodontitis / Q000382:microbiology* / Q000532:radiotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology; D016966:Porphyromonas gingivalis / Q000187:drug effects / Q000528:radiation effects; D013291:Streptococcus / Q000187:drug effects / Q000528:radiation effects; D014048:Tolonium Chloride / Q000494:pharmacology
D017319:Photosensitizing Agents; D014048:Tolonium Chloride; D001587:Benzoylarginine-2-Naphthylamide