Photodynamic Inactivation of Cariogenic Pathogens Using Curcumin as Photosensitizer.

OBJECTIVE

This investigation assessed the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to Photodynamic Therapy (PDT) when grown simultaneously in dentine carious lesions.

BACKGROUND DATA

PDT is a technique that utilizes light to activate photosensitizers in the presence of oxygen to produce reactive radicals.

MATERIALS AND METHODS

A culture medium of 1% glucose, 2% sucrose, 1% young primary culture of L. acidophilus 10 CFU/mL, and S. mutans 10 CFU/mL was utilized to inoculate the bacterial induced caries on human dentine slabs. Different concentrations of the photosensitizer (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were activated through exposure to the light-emitting diode source with a central wavelength of 450 nm and a fluency of 5.7 J/cm. Two light intensities (19 and 47.5 mW/cm) were tested. Four different groups were analyzed: L-D- (control group), L-D+ (drug group), L+D+1 (PDT group 1, light intensity of 19 mW/cm), and L+D+2 (PDT group 2, light intensity of 47.5 mW/cm). ANOVA/Tukey tests were utilized to compare groups (α = 5%).

RESULTS

Both light intensities required 5.0 g/L of curcumin for significant bacterial reduction (p < 0.05). No significant effect was found for L-D+, thus proving the absence of a potential inherent toxicity.

CONCLUSIONS

Curcumin has a toxic effect on microorganisms at appreciable concentrations upon photoactivation. However, it was required to use the maximum concentration of the drug for a successful procedure.