Abstract
IntroductionPhotodynamic therapy (PDT) is a treatment modality involving a dye that is activated by exposure to light of a specific wavelength in the presence of oxygen to form oxygen species causing localised damage to microorganisms.AimTo determine the most effective bactericidal incubation and irradiation times of erythrosine-based PDT on in vivo-formed dental plaque biofilms.MethodsA randomised controlled study; 18-healthy adult participants wearing intraoral appliances with human enamel slabs to collect dental plaque samples in two separate periods of two weeks each for use in arm-1 and arm-2. These accumulated dental plaque samples were treated with PDT under different experimental conditions. Incubation times with photosensitiser (erythrosine) of 15 min and 2 min were used in arm-1 and arm-2, respectively, followed by light irradiation for either 15 min (continuous) or as a fractionated dose (5 × 30 sec). Following treatment, percentage reductions of total bacterial counts were compared between the different groups. In addition, confocal laser scanning microscopy (CLSM) and LIVE/DEAD® BacLight™ Bacterial Viability Kit were used to visualise the effect of PDT on in vivo-formed biofilms.ResultsSignificant reductions in the percentage of total bacterial counts (~93–95%) of in vivo-formed biofilms were found when using either 2 min or 15min incubation times and applying 15 min continuous light. Although when applying fractionated light, there was more cell death when 15 min incubation time was used (~ 91%) compared with the 2 min incubation time (~ 64%). CLSM results supported these findings.ConclusionImproving the clinical usefulness of PDT by reducing its overall treatment time seems to be promising and effective in killing in vivo-formed dental plaque biofilms.
Highlights
IntroductionIncreases in the incidence of antibiotic/antimicrobial drugresistant bacteria necessitates the development of alternative approaches to the control of dental plaque (Wainwright and Crossley 2004; Meisel and Kocher 2005)
Photodynamic therapy (PDT) is a treatment modality involving a dye that is activated by exposure to light of a specific wavelength in the presence of oxygen to form oxygen species causing localised damage to microorganisms
To ensure that the baseline measurement of the accumulated plaque in all the six slabs were comparable, we investigated the variation of bacterial viability counts among these slabs from one participant prior to the main study PDT investigation
Summary
Increases in the incidence of antibiotic/antimicrobial drugresistant bacteria necessitates the development of alternative approaches to the control of dental plaque (Wainwright and Crossley 2004; Meisel and Kocher 2005). There are limitations associated with the conventional approaches to controlling dental plaque, such as parents’. In the previous studies, the PDT treatment time has been longer than would be ideal for the clinical setting (Metcalf et al 2006; Wood et al 2006; Tahmassebi et al 2015). There were no reports in the literature that have compared the efficacy of PDT on in vivo formed plaque biofilms with different incubation times with erythrosine photosensitiser prior to irradiation. To further study this and enhance clinical usefulness, this work was conducted aiming to reduce the overall treatment time for PDT by investigating the bactericidal efficacy after different incubation and irradiation times
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