Investigation of bactericidal effect of low level laser of Galium-Aluminium-Arsenide on cariogenic species of Streptococci and Lactobacillus

Abstract

The aim of present in vitro study was to investigate the antibacterial effect of low level laser of Galium Aluminium Arsenide (GaAlAs) on cariogenic bacteria. Suspensions of Streptococci mutans, Streptococci sanguis, Streptococci subrinus, Streptococci salivarius and Lactobacillus sp. were exposed to a GaAlAs (890 nm) in the presence of photosensitizer toluidine blue O in different time points of 2, 5, 12, 16 and 20 min. Viable microorganisms were counted on muller hinton agar plates after overnight incubation at 37°C and reported as colony forming unit. For all tested bacterial strains, at time points of 5, 12, 16 and 20 min, there was a significant decrease in the viable counts, reaching to a maximum value of 100% after 20 min, when treated with combination of laser + TBO (toluidine blue O). The combination of laser and TBO had the least effect on Lactobacillus sp. in time points of 5, 12 and 16 min, whereas it was more effective against S. mutans and S. sanguis at the same time points. Based on the presented results, we may conclude that the low level laser of GaAlAs was effective in significantly reducing of the viability of oral cariogenic bacteria in vitro.