In vitro and in situ studies have demonstrated that the photodynamic antimicrobial therapy (PACT) is effective in reducing Streptococcus mutans population in artificially carious dentin.
This pilot in vivo study evaluated the antimicrobial effect of PACT using toluidine blue O (TBO) and a light-emitting diode (LED) in carious dentin lesions. Five healthy adult volunteers (19-36 yr), with at least 4 active carious cavities each, participated in this study. Teeth of each volunteer were randomly divided into four groups: (1) without TBO and without light (Control); (2) with TBO alone (TBO); (3) with LED at 94/J cm2 alone (LED); and (4) with TBO plus LED at 94 J/cm2 (PACT). Each cavity was divided into two halves. The baseline carious dentin sample was collected from half of each cavity. Following, the treatments were performed using a random distribution of tooth into treatments. Then, the second collection of carious dentin samples was performed. Before and after treatments, dentin samples were analyzed with regard
to the counts of total viable microorganisms, total streptococci, mutans streptococci, and lactobacilli. The data were statistically analyzed by Kruskal-Wallis and Student-Newman-Keuls
tests (α=5%). Log reductions ranged from -0.12 to 2.68 and significant reductions were observed for PACT (group 4) when compared to the other groups (1, 2, and 3) for total
streptococci and mutans streptococci. Concluding, PACT was effective in killing oral
microorganisms present in in vivo carious dentin lesions and may be a promising technique for
eliminating bacteria from dentin before restoration.
The purpose of this in vitro study was to determine whether low-level laser light in the presence of a photosensitizer can kill streptococci in human saliva. Samples of stimulated saliva were collected from ten healthy subjects. These samples were mixed and exposed to a gallium-aluminium-arsenide laser light (660 nm) in the presence of toluidine blue O. Viable total streptococci and mutans streptococci were counted on plates with MSA and MSB, respectively, following incubation at 37 degree(s)C, 10% CO2 for 48 hours. The exposure of saliva to laser light in the absence of the dye, or the dye in the absence of the laser light showed no significant effect on the viability of the microorganisms. A decrease in the number of viable microorganisms was only verified when they were exposed to both the laser light and the dye at the same time. A total inhibition growth of the mutans streptococci and a substantial killing rate of total streptococci were achieved with a dye concentration of 100 mg/mL and an energy density of 28.8 J/cm2. These results imply that total streptococci and mutans streptococci present in human saliva can be killed by low-level laser light in the presence of toluidine blue O.
The aim of this in vitro study was to determine whether low-level laser light in the presence of a photosensitizer could kill Streptococcus mutans and Streptococcus sobrinus. Suspensions of these microorganisms were exposed to a gallium-aluminium-arsenide laser light (660 nm) in the presence of photosensitizer toluidine blue O. Viable microorganisms were counted on brain heart agar plates after incubation at 37 degree(s)C in partial atmosphere of 10% CO2 for 48 hours. Their exposure to the laser light in the absence of the dye or the dye in the absence of the laser light presented no significant effect on the viability of the microorganisms. However, a decrease in the number of viable microorganisms was only verified when they were exposed to both the laser light and the dye at the same time. Their total growth inhibition was achieved with a dye concentration of 100 mg/mL and a light energy density of 28.8 J/cm2, after being exposed to laser light for 900 seconds. In conclusion, these results imply that these bacteria can be killed by low-power laser light in the presence of the photosensitizer.
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