(PO46) Antimicrobial photodynamic therapy of Indocyanine Green suspended in nanobubble water against E.faecalis

Abstract: Antimicrobial photodynamic therapy (aPDT) is a process in which a photosensitizer, upon activation in the presence of oxygen, produces radicals and reactive oxygen species (ROS) that are cytotoxic to microbes. The generation of ROS is proportional to the availability of surrounding oxygen. Root canals have low availability of surrounding oxygen, and the study aims to incorporate Indocyanine Green (ICG) in nanobubble water (NBW) to increase the availability of oxygen. In the study, E. faecalis strain ATCC® 29212 was inoculated in brain heart media (BH) for 14 hours at 37°C. The experimental groups were divided as follows: Group 1. Control – Deionized Water (DIW); 2. Nanobubble Water (NBW); 3. Indocyanine Green + DIW (ICG); 4. 810 nm Diode Laser (Laser); 5. NBW + ICG dissolved in DIW; 6. Laser + ICG dissolved in DIW; 7. Laser + NBW; and 8. Laser + ICG dissolved in NBW (Laser + ICG + NBW). The samples were centrifuged at 3000 rpm for 5 minutes, and the supernatant was pipetted. The pellets were resuspended and treated respective to each group. Treated groups were resuspended in BH media and incubated overnight. The absorbance readings of each of the culture groups at 480 nm were recorded for quantification of bacterial growth. Statistically significant reduction in E. faecalis growth was observed in Groups 2, 4, 6, 7, and 8. The experiment has shown the effectiveness of NBW and 0.1M ICG when irradiated with a laser at 10 J/cm². The action of ROS generation when the ICG is stimulated by the laser is most effective with the presence of surrounding oxygen, which is supplied by the NBW.