Effect of Indocyanine Green and Infrared Diode Laser toStreptococcus mutansBiofilms

Objective:The aim of this study was to quantitatively and qualitatively evaluate the effects of the indocyanine green (ICG)-near-infrared (NIR) photoreaction onStreptococcus mutansbiofilms. Background:ICG recently emerged as a photosensitive agent for photodynamic therapy. Although the effects of ICG-NIR onS. mutansinhibition are documented, little is known about its influence on biofilms, which are resistant to antimicrobial treatment and a major cause of plaque that leads to dental caries. Methods:ICG was used as a photosensitizer with a diode laser irradiated in a rectangular shape (810 nm, 300 mW) as a light source onS. mutansATCC 25175 biofilms. Viability was determined by the colony forming unit (CFU) count and confocal laser-scanning microscopy. The biofilm surface temperature was measured with a one-channel thermocouple thermometer. Results:ICG and NIR diode laser significantly decreased the CFU count ofS. mutanscompared with the control group in a time-dependent manner. When irradiated with light after ICG application, temperature changes of 8.4 degrees C, 12.4 degrees C, and 14.9 degrees C were observed with 10, 30, and 60 sec of irradiation, respectively. Conclusions:The ICG-NIR diode laser photoreaction can inhibitS. mutansbiofilms, especially at 60 sec. An optimized protocol is needed for clinical application of ICG-NIR diode laser treatment.