Relative distribution among the volunteers and total distribution (in percentages) of the initially adherent bacterial species from 6 individuals after application of antimicrobial photodynamic therapy (aPDT) using visible light (VIS) plus water-filtered infrared-A (wIRA).

<p>Graph A depicts the bacterial composition of the untreated negative controls. Graphs B and C show the bacterial composition after the <i>ex vivo</i> treatment with VIS + wIRA and the photosensitizers (100 μg/ml) toluidine blue (TB) and chlorine e6 (Ce6) on oral microorganisms after a 2-hour (h) cultivation <i>in situ</i>. Consistent color coding was used for the study participants and detected bacteria as indicated by the schemes at the left and right of panels A, B and C respectively.</p

Individual upper jaw acrylic splint with six bovine enamel slabs (BES) embedded in silicon at different sites.

<p>The BES were fixed at the front (f), in the middle (m) and at the back (b), for both the right (R) and left (L) sides of the splint. Silicon covered the downward-facing surfaces and the margins of the BES and left only their upward-facing surfaces exposed.</p

Representative illustration of the application of antimicrobial photodynamic therapy using visible light (VIS) plus water-filtered infrared-A (wIRA) on oral microorganisms.

<p>In brief, a VIS + wIRA radiating device with a broadband water-filtered spectrum (570–1400 nm) enables the excitation of the tested photosensitizers toluidine blue (TB) and chlorine e6 (Ce6). As a result, these interact with oxygen (O₂) inducing the release of a variety of reactive oxygen species (ROS), which can destroy planktonic and oral biofilm microorganisms.</p

Diagram of the colony forming units (CFUs) depicting the effect of photodynamic therapy using visible light (VIS) plus water-filtered infrared-A (wIRA) against oral microorganisms during initial adhesion (A) and biofilm formation (B), respectively.

<p>The photosensitizers toluidine blue (TB) and chlorine e6 (Ce6) were applied (100 μg/ml) <i>ex vivo</i> onto the oral microorganisms after 2 hours (h) or 3 days (d) of <i>in situ</i> cultivation, respectively. An untreated specimen and a chlorhexidine-treated (CHX) specimen served as negative and positive controls. A log₁₀ scale per square centimeter (log₁₀ / cm²) indicates the CFUs. The p-values (t-test) of the significantly different data are depicted above.</p

Antimicrobial Photoinactivation Using Visible Light Plus Water-Filtered Infrared-A (VIS + wIRA) Alters <i>In Situ</i> Oral Biofilms

<div><p>Recently, growing attention has been paid to antimicrobial photodynamic therapy (aPDT) in dentistry. Changing the microbial composition of initial and mature oral biofilm by aPDT using visible light plus water-filtered infrared-A wavelengths (VIS + wIRA) has not yet been investigated. Moreover, most aPDT studies have been conducted on planktonic bacterial cultures. Therefore, in the present clinical study we cultivated initial and mature oral biofilms in six healthy volunteers for 2 hours or 3 days, respectively. The biofilms were treated with aPDT using VIS+wIRA (200 mW cm^-2), toluidine blue (TB) and chlorine e6 (Ce6) for 5 minutes. Chlorhexidine treated biofilm samples served as positive controls, while untreated biofilms served as negative controls. After aPDT treatment the colony forming units (CFU) of the biofilm samples were quantified, and the surviving bacteria were isolated in pure cultures and identified using MALDI-TOF, biochemical tests and 16S rDNA-sequencing. aPDT killed more than 99.9% of the initial viable bacterial count and 95% of the mature oral biofilm <i>in situ</i>, independent of the photosensitizer. The number of surviving bacterial species was highly reduced to 6 (TB) and 4 (Ce6) in the treated initial oral biofilm compared to the 20 different species of the untreated biofilm. The proportions of surviving bacterial species were also changed after TB- and Ce6-mediated aPDT of the mature oral biofilm, resulting in a shift in the microbial composition of the treated biofilm compared to that of the control biofilm. In conclusion, aPDT using VIS + wIRA showed a remarkable potential to eradicate both initial and mature oral biofilms, and also to markedly alter the remaining biofilm. This encourages the clinical use of aPDT with VIS + wIRA for the treatment of periimplantitis and periodontitis.</p></div