Energy Dose Parameters Affect Antimicrobial Photodynamic Therapy–Mediated Eradication of Periopathogenic Biofilm and Planktonic Cultures

Abstract

This study demonstrated that three important periopathogens are susceptible to aPDT-mediated killing, regardless of whether they are present in planktonic or biofilm form. Furthermore, a clear energy dose-dependence exists with this treatment that should to be taken into account when determining optimal treatment times in clinical application.

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

“…Thus, it is likely that several therapeutic parameters such as photosensitizer dose, photosensitizer-light interval and light conditions may require optimization to increase efficacy. A study by Street et al has confirmed that the efficacy of a-PDT against three major periodontal pathogens was light dose dependent [10]. Also, there are reports showing that light dose fractionation may add some benefit to the treatment.…”

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer againstPseudomonas aeruginosaPAO1

“…The higher tolerance of the biofilm grown under flow with respect to the biofilm grown in the microplate system could be due to the nature of the biofilm. Biofilms characterized by different age, thickness and matrix composition can show different sensitivities to PDT (Street et al 2010). In the present experimental conditions the biofilms differed not only in age, but also in the presence or absence of flow, which in turn affects nutrient availability and the biofilm architecture.…”

Chapter 13. Antimicrobial Photodynamic Therapy (aPDT) for Oral Infections

“…Indeed, when the susceptibility of the three ''key'' periodontal pathogens grown as biofilms in vitro has been investigated the reductions have been in the order of 99.9%. 51 Pfitzner et al 52 used several experimental photosensitizers and light doses in excess of 20 J cm À2 to completely eradicate cultures of P. gingivalis and F. nucleatum. Furthermore, Chan and Lai 53 showed that Gram-negative anaerobes were susceptible to methylene blue mediated aPDT, with F. nucleatum and A. actinomycetemcomitans being reduced by about 95% compared to the non-treated control.…”

“…Reasons for this variability, while likely in part due to small sample sizes of studies published to date, can be theorized from preclinical studies that preceded this clinical work. As demonstrated in several preclinical aPDT studies, 51,97,98 the importance of delivering an optimal activating light energy dose cannot be understated. While it is difficult to pinpoint a precise power density or energy dose threshold for clinical use using preclinical results, it is clear that antibacterial efficacy drops off dramatically when insufficient light is delivered to the site of treatment.…”