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Randomized Controlled Trial
. 2021 Oct;22(5):791-800.
doi: 10.1007/s40368-021-00637-y. Epub 2021 Jun 5.

Treatment of dental plaque biofilms using photodynamic therapy: a randomised controlled study

A Alsaif  1   2 , J F Tahmassebi  3 , S R Wood  4
Affiliations
Randomized Controlled Trial

Treatment of dental plaque biofilms using photodynamic therapy: a randomised controlled study

A Alsaif et al. Eur Arch Paediatr Dent. 2021 Oct.

Abstract

Introduction: 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.

Aim: To determine the most effective bactericidal incubation and irradiation times of erythrosine-based PDT on in vivo-formed dental plaque biofilms.

Methods: A 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.

Results: Significant 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.

Conclusion: Improving 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.

Keywords: Antimicrobial; CLSM; Erythrosine; In vivo biofilm; Incubation time; Irradiation time.

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Conflict of interest statement

The authors declare no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Figures

Fig. 1
Fig. 1
Preparation of in situ appliance. a Illustration of tooth sectioning. b Right and left lateral views of in situ appliance. c Enamel slab in in situ appliance
Fig. 2
Fig. 2
Laboratory protocol of PDT on in vivo-formed plaque biofilms
Fig. 3
Fig. 3
Percentage (%) reduction in viable counts of in vivo formed biofilms under different experimental conditions: C1 (No erythrosine, no light); C2 (Erythrosine, no light); T1A and T1B (Erythrosine, +15 min continuous light); T2A and T2B (Erythrosine, +30 sec light pulses for 5 times, separated by dark periods of 1 min) (a, b). Data represent median values a (n = 13) b (n = 15). Error bars represent SD and data followed by different letters differ statistically (p < 0.003).
Fig. 4
Fig. 4
CLSM images of 14-day in vivo formed biofilm samples (a–f). a, b Untreated (control) biofilm samples. Aggregates of bacteria were separated by fluid filled voids (black holes-red arrow). c, d Biofilm samples incubated with erythrosine (220 μM) for (c) 15 min or (d) 2 min and irradiated for continuous 15 min. e, f biofilm samples incubated with erythrosine (220 μM) for (e) 15 min or (f) 2 min and irradiated for fractionated 5 × 30 sec with 1min dark recovery periods. Green fluorescence indicates viable bacteria and red/yellow fluorescence indicates affected bacteria. All images were taken with ×63 lens
See this image and copyright information in PMC

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