Photodynamic potential of curcumin and blue LED against Streptococcus mutans in a planktonic culture

Background: The photodynamic therapy (PDT) involves the use of light of specific wavelength toactivate a nontoxic photosensitizing agent or dye in the presence of oxygen for eradication oftarget cells. In dentistry, this therapy is used to suppress the growth of microorganisms involveddirectly with dental decay and periodontitis process. There are evidences that curcumin dye isable to control microbial activity when illuminated with specific wavelength. The purpose ofthis study was to evaluate the in vitro efficacy of PDT using curcumin dye (Cur-C) in combinationwith a blue LED (L) device on a planktonic model of Streptococcus mutans (S. mutans). Methods: Suspensions (0.5 mL) containing S. mutans at 1 × 107CFU mL-1were prepared anddivided into 4 groups: Group C- L- (control: no treatment and 1 experimental condition),Group C + L- (curcumin at 3 different concentrations: 2000; 4000 and 8000 M and 3 exper-imental conditions), Group C- L+ (LED at 3 different dosages: 24, 48 and 72 J cm-2and 3experimental conditions), and Group C + L+ (PDT group: curcumin at respective concentrationscombined to LED dosages and 9 experimental conditions). Samples of each experimental con-dition were cultured in Petri dishes of BHI agar. Incubation in micro-aerophilia at 37◦C for 48 hwas performed for subsequent visual counting of CFU/mL. Data were transformed into log10and analyzed by two-way ANOVA and Tukey s test at p < 0.05