Effect of Various Photosensitizers on Blue Light Phototoxicity against VSC Producing Bacteria

Objectives: Oral halitosis is considered to result mainly due to the production of volatile sulfide compounds (VSC) by anaerobic bacteria situated deep within the oral biofilm. Previously, we have shown that these bacteria were susceptible to high intensity blue light (400- 500 nm; 1500 mW/cm²). In the present study, we tested the effect of blue light in the presence of various exogenous photosensitizers on malodor production in an experimental oral biofilm.
Methods: Biofilms were exposed to a plasma-arc light source for 30, 60, and 120 sec (i.e. fluences of 41, 82, and 164 J/cm², respectively) with or without the addition of erythrosine B, natural red and rose Bengal (0.01, 0.1 and 1% w/v, respectively). Following light exposure biofilm samples were examined for malodor production (Odor judge), VSC production (Halimeter^TM), VSC producing bacteria quantification using light microscopy-based sulfide assay (MSA) and reactive oxygen species (ROS) production quantification using the fluorogenic reagent 2’, 7’- dichlorofluorescin diacetate.
Results: Results showed that the exposure of experimental oral biofilm to high intensity blue light in the presence of rose bengal caused a significant reduction in malodor production, VSC levels and VSC producing bacteria quantification concomitant with an increase in ROS producing.
Conclusions: These results suggest that rose bengal promotes blue light phototoxicity against malodor producing bacteria mediated by increased ROS production.