Blue light commonly used by dentists to cure resin fillings and hydrogen peroxide (H₂O₂) combined may be capable of reaching and treating bacteria in deep layers of biofilms that can cause cavities and gingivitis. The researchers from Hebrew University, Hadassah, Jerusalem, Israel and the University of California San Francisco report their findings in the July 2008 issue of the journal Antimicrobial Agents and Chemotherapy.

Most bacteria in nature exist in communities of biofilms, structures that serve as physical barriers and severely limit the effect of antibacterial agents. Oral biofilms are commonly associated with infections such as cavities, gingivitis and periodontal disease. With antibiotic resistance continually on the rise, researchers are exploring alternative sterilization methods to effectively treat biofilms.

In the study biofilms of Streptococcus mutans were exposed to wavelengths of visible light consisting of 400 to 500 nm for 30 to 60 seconds while in the presence of 3 to 300 mM of hydrogen peroxide. Microbial counts from each treated sample were compared with those of the control and results showed that visible light and hydrogen peroxide combined successfully penetrated all layers of the biofilm creating an antibacterial effect.

"The ability of noncoherent visible light in combination with H₂O₂ to affect bacteria in deep layers of the biofilm suggests that this treatment may be applied in biofilm-related diseases as a minimally invasive antibacterial procedure," say the researchers.

(D. Steinberg, D. Moreinos, J. Featherstone, M. Shemesh, O. Feuerstein. 2008. Genetic and physiological effects of noncoherent visible light combined with hydrogen peroxide on Streptococcus mutans in biofilm. Antimicrobial Agents and Chemotherapy<
'/>"/>