Light-Sensitive bacteria and periodontal disease .....

Phototargeting Oral Black-Pigmented Bacteria
Nikolaos S. Soukos,1* Sovanda Som,1 Abraham D. Abernethy,1 Karrian
Ruggiero,1 Joshua Dunham,1
Chul Lee,2 Apostolos G. Doukas,3 and J. Max Goodson4
Applied Molecular Photomedicine Laboratory1 and Clinica
Collaborative,4 The Forsyth Institute, and Wellman Center for
Photomedicine, Massachusetts General Hospital, Harvard Medical School,
Boston, Massachusetts, and Division of
Human Nutrition, Department of Preventive Medicine and Communit
Health, School of Medicine,
The University of Texas Medical Branch, Galveston, Texas2
Received 31 August 2004/Returned for modification 23 Novembe
2004/Accepted 26 December 2004



We have found that broadband light (380 to 520 nm) rapidly an
selectively kills oral black-pigmented bacteria
(BPB) in pure cultures and in dental plaque samples obtained from huma
subjects with chronic periodontitis.
We hypothesize that this killing effect is a result of light excitatio
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 o
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 plaqu
samples by DNA-DNA hybridization
for 40 taxa before and after phototherapy showed that the growth of th
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 energ
fluences. The present study suggests that
intraoral light exposure may be used to control BPB growth and possibl
benefit patients with periodontal disease

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Joel34
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