Method: Planktonic suspensions of S. mutans were standardized and submitted to PACT treatment at low concentrations of curcumin (C) and TBO (T) exposed to 42 J/cm2 of a white light (WL) (C+WL+ and T+WL+: PACT groups); isolated effect of both C (C+WL-) and T concentrations (T+WL-); effect of light source (C-WL+ and T-WL+) and suspensions neither submitted to PS nor LED illumination (control groups: C-WL- and T-WL-). Aliquots of each group were diluted and cultured on blood agar plates and incubated at 37ºC, 5% CO2 for 24 h. The number of Colony Forming Units (CFU)/mL was recorded, transformed into log10 and analyzed by ANOVA and Tukey´s test at cut-off value at 0.05.
Result: The groups submitted to PACT presented a substantial photobacteridical rate (~99.9%) in comparison to control groups (p < 0.05). PS or LED lights used alone demonstrated no effect on the number of viable bacterial counts.
Conclusion: PACT using the novel LED device, which needs a short illumination exposure time and allows the use of a single source of light, in combination with low concentrations of photosensitizers is potentially an effective antimicrobial in vitro approach to reduce number of microorganisms related to dental caries process.