Scientific studies

Photodynamic therapy in the control of oral biofilms.
Soukos NS, Goodson JM. Periodontol 2000. 2011 Feb;55(1):143-66.


Microbial biofilms in the oral cavity are involved in the etiology of various oral conditions, including caries, periodontal and endodontic diseases, oral malodor, denture stomatitis, candidiasis and dental implant failures. It is generally recognized that the growth of bacteria in biofilms imparts a substantial decrease in susceptibility to antimicrobial agents compared with cultures grown in suspension. It is therefore not surprising that bacteria growing in dental plaque, a naturally occurring bio lm, display increased resistance to antimicrobial agents. Current treatment techniques involve either periodic mechanical disruption of oral microbial biofilms or maintaining therapeutic concentrations of antimicrobials in the oral cavity, both of which are fraught with limitations. The development of alter- native antibacterial therapeutic strategies therefore becomes important in the evolution of methods to control microbial growth in the oral cavity. The use of photodynamic therapy for inactivating microorganisms was first demonstrated more than 100 years ago, when Oscar Raab reported the lethal effect of acridine hydrochloride and visible light on Paramecia caudatum. Photodynamic therapy for human infections is based on the concept that an agent (a photosensitizer) which absorbs light can be preferentially taken up by bacteria and subsequently activated by light of the appropriate wavelength in the presence of oxygen to generate singlet oxygen and free radicals that are cytotoxic to microorganisms. Because of the primitive molecular nature of singlet oxygen, it is unlikely that microorganisms would develop resistance to the cytotoxic action. Photodynamic therapy has emerged as an alternative to antimicrobial regimes and mechanical means in eliminating dental plaque species as a result of the pioneering work of Professor Michael Wilson and colleagues at the Eastman Dental Institute, University College London, UK. In this review, we propose to provide an overview of photodynamic therapy with emphasis on its current status as an antimicrobial therapy to control oral bacteria,  and review the progress that has been made in the last 15 years concerning the applications of photodynamic therapy for targeting bio lm-associated oral infections. Problems and challenges that have arisen will be identified and discussed. Finally, new frontiers of antimicrobial photodynamic therapy research will be introduced, including targeting strategies that may open new opportunities for the maintenance of bacterial homeostasis in dental plaque, thereby providing the opportunity for more effective disease prevention and control. 

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Treatment of residual pockets with photodynamic therapy, diode laser, or deep scaling. A randomized, split-mouth controlled clinical trial.

Cappuyns I, Cionca N, Wick P, Giannopoulou C, Mombelli A. Lasers Med Sci. 2012 Sep;27(5):979-86. Epub 2011 Nov 22.


The objective of this work was to compare the effects of antimicrobial photodynamic therapy (PDT), diode soft laser therapy (DSL), and thorough deep scaling and root planing (SRP) for treatment of residual pockets. Thirty-two subjects with a history of non-surgical treatment for chronic periodontitis were included. Residual pockets >4 mm and bleeding upon probing were debrided with an ultrasonic device and then subjected to either PDT, DSL, or SRP. Pocket probing depth (PPD), bleeding on probing (BOP), and gingival recession were monitored over 6 months. Counts of four microorganisms were determined by direct hybridization with RNA probes. PPD decreased from 5.6 ± 1.0 to 3.8 ± 1.1 in 6 months (p < 0.001), and BOP decreased from 100% to 52% (p < 0.01). The risk for a site to remain >4 mm with BOP depended on initial PPD (p = 0.036) and was higher if treated with DSL (p = 0.034). Frequencies of three microorganisms were significantly lower in PDT- and SRP- treated than in DSL-treated quadrants (p = 0.02) after 14 days, but not at months 2 and 6. All three treatments resulted in a significant clinical improvement. PDT and SRP suppressed Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola stronger, and resulted in fewer persisting pockets after 6 months, than DSL application.