Antimicrobial Photodynamic Therapy Mediated by Curcumin Reduces the Viability of Microcosm Biofilms Originated From Dentin Caries Lesions

Objectives: This in vitro study aimed to assess the ability of the Antimicrobial Photodynamic Therapy (aPDT) in killing microorganisms from microcosm biofilms originated from dentin caries lesions.
Methods: Biofilms were grown on 48 dentin discs for 5 days at 37^oC anaerobically (modified McBain medium supplemented with 1% sucrose). Biofilms were treated with different protocols of aPDT, by the association of two concentration of curcumin (0 or 100 mg.mL^-1) and four densities of energy of a LED 630 nm at 40 mW (0, 18.75, 37.5 or 75 J.cm^-2). The viability of total microorganisms, lactobacilli, total streptococci, and mutans streptococci were determined by Colony Forming Units (CFU) counted on Petri’s dishes with respective selective media: Blood Soy agar, Rogosa agar plus 0.13% acetic acid, Mitis Salivarius agar, and Mitis Salivarius agar plus 20% sucrose and 0.2 U/mL bacitracin. Statistical analysis was performed by Kruskal-Wallis and Dunn’s post-hoc tests (P<0.05).
Results: A dose-dependent effect of aPDT was demonstrated. The curcumin and red LED alone did not reduce the viability of biofilms significantly, except for 75 J.cm^-2 LED on total microorganisms. Besides, the combination of 100 mg.ml^-1 curcumin and 37,5 J.cm^-2 LED produced the highest reduction of total microorganisms (2.47 Log10) and total streptococci (1.98 Log10), while the combination of 100 mg.ml^-1 curcumin and 75 J.cm^-2 LED still reduced lactobacilli (2.65 Log10) and mutans streptococci counts (2.08 Log10).
Conclusions: Therefore, aPDT mediated by curcumin reduces the viability of microcosm biofilms from dentin caries lesions.