Dual-Light Photodynamic Therapy Effectively Eliminates Streptococcus Oralis Biofilms.

During cancer treatment, oral mucositis due to radiotherapy or chemotherapy often leads to disruption of the oral mucosa, enabling microbes to invade bloodstream. Viridans streptococcal species are part of the healthy oral microbiota but can be frequently isolated from the blood of neutropenic patients.  We have previously shown the antibacterial efficacy of dual-light, the combination of antibacterial blue light (aBL) and indocyanine green photodynamic therapy (aPDT). Here, we investigated the dual-light antibacterial action against four-day Streptococcus oralis biofilm. In addition, while keeping the total radiant exposure constant at 100J/cm2, we investigated the effect of changing the different relative light energies of aBL and aPDT to the antibacterial potential. The dual-light had a significant antibacterial effect in all the tested combinations. Dual-light can be used as an effective disinfectant against S. oralis biofilm.