Antimicrobial efficacy of photodynamic therapy using two different light sources on the titanium-adherent biofilms of Aggregatibacter actinomycetemcomitans: An in vitro study

Background: Antimicrobial photodynamic therapy (aPDT), is a promising approach proposed as an adjunct for the decontamination of dental implant surfaces. This study aimed to investigate the effect of aPDT with laser or light emitting diode (LED) compared with conventional chlorhexidine treatment on the titanium-attached biofilms of Aggregatibacter actinomycetemcomitans. Methods and materials: Thirty-six acid-etched and sandblasted (SLA) titanium discs were allocated to six groups and incubated with the titanium-adherent biofilms of A. actinomycetemcomitans as follows. Negative control (no treatment applied), positive control (0.2% chlorhexidine solution), 0.1 mg/mL Toluidine Blue [TBO] group, aPDT-treated groups subjected either to diode laser with a wavelength of 635 nm wavelength or LED with the peak wavelength of 630 nm with TBO as photosensitizer and sterile control (not contaminated). Following sonication and transferring the specimens to the microplate, the number of colony-forming units (CFUs) per disc was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and additional post hoc tests with the level of significance set at P < 0.05. Results: aPDT using TBO + LED was significantly more effective (0.93 ± 0.24 × 104) in the suppression of A. actinomycetemcomitans compared with TBO + Laser (2.65 ± 0.7 × 104). However, the lowest mean of CFU count was found in sterile, and chlorhexidine groups, respectively (P < 0.0001) and the highest bacterial count was observed in the negative control group (P < 0.0001). Conclusions: LEDs and diode lasers have a lower ability to suppress A. actinomycetemcomitans biofilms compared to 0.2% chlorhexidine in vitro. However, the aPDT with the use of LED as a light source and TBO as a photosensitive agent could be an appropriate alternative to conventional chlorhexidine treatment.