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Photodestruction of human dental plaque bacteria: Enhancement of the photodynamic effect by photomechanical waves in an oral biofilm model
Author(s) -
Soukos Nikolaos S.,
Mulholland Stephen E.,
Socransky Sigmund S.,
Doukas Apostolos G.
Publication year - 2003
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.10208
Subject(s) - biofilm , photodynamic therapy , dental plaque , dentistry , chemistry , bacteria , biophysics , microbiology and biotechnology , medicine , materials science , biology , genetics , organic chemistry
Background and Objectives Periodontal disease results from the accumulation of subgingival bacterial biofilms on tooth surfaces. There is reduced susceptibility of these biofilms to antimicrobials for reasons that are not known. The goals of this study were to investigate the photodynamic effects of a conjugate between the photosensitizer (PS) chlorin e6 (c e6 ) and a poly‐ l ‐lysine (pL) with five lysine residues on human dental plaque bacteria as well as on biofilms of the oral species Actinomyces naeslundii after their exposure to photomechanical waves (PW) generated by a laser in the presence of the conjugate. Study Design/Materials and Methods Subgingival plaque samples from 12 patients with chronic destructive periodontitis were divided in 3 groups that were incubated for 5 minutes with 5 μM c e6 equivalent from the pL–c e6 conjugate in the presence of fresh medium (group I), PBS (group II), and 80% PBS/20% ethylenediaminetetra‐acetic acid (EDTA) (group III) and were exposed to red light. Also, biofilms of A. naeslundii (formed on bovine enamel surfaces) were exposed to PW in the presence of 5 μM c e6 equivalent from the pL–c e6 conjugate and were then irradiated with red light. The penetration depth of the conjugate was measured by confocal scanning laser microscopy (CSLM). In both cases, after illumination serial dilutions were prepared and aliquots were spread over the surfaces of blood agar plates. Survival fractions were calculated by counting bacterial colonies. Results The PS/light combination achieved almost 90% killing of human dental plaque species. In biofilms of A. naeslundii , CSLM revealed that PW were sufficient to induce a 50% increase in the penetration depth of the pL–c e6 conjugate into the biofilm. This enabled its destruction (99% killing) after photodynamic therapy (PDT). Conclusions PW‐assisted photodestruction of dental plaque may be a potentially powerful tool for treatment of chronic destructive periodontal disease. Lasers Surg. Med. 33:161–168, 2003. © 2003 Wiley‐Liss, Inc.