Comparative effects of photodynamic therapy mediated by curcumin on standard and clinical isolate of Streptococcus mutans.

AIM: The aim of this study was investigate the effect of photodynamic therapy (PDT) using curcumin (C) as a photosensitizing agent irradiated with an LED (L) in the blue wavelength as a light source on a standard and clinical isolate of Streptococcus mutans (S. mutans) in a planktonic suspension model. MATERIALS AND METHODS: Suspensions of both strains were divided into 4 groups as follows: absence of C and L (control group: C-L-), with C and without L (C group: C+L-), absence of C with L (L group: C-L+) and presence of C and L (PDT group: C+L+). Three different concentrations of curcumin (0.75 mg/ml, 1.5 mg/ml and 3 mg/ml) and three light fluences of studied light source (24, 48 and 72 J cm(-2)) were tested. Aliquots of each studied group was plated in BHI agar and submitted to colony forming units counting (CFU/ml) and the data transformed into logarithmical scale. RESULTS: A high photoinactivation rate of more than 70% was verified to standard S. mutans strain submitted to PDT whereas the clinical isolate showed a lower sensitivity to all the associations of curcumin and LED. A slight bacterial reduction was verified to C+L- and C-L+, demonstrating no toxic effects to the isolated application of light and photosensitizer to both S. mutans strains tested. CONCLUSION: Photodynamic therapy using a combination of curcumin and blue LED presented a substantial antimicrobial effect on S. mutans standard strain in a planktonic suspension model with a less pronounced effect on its clinical isolate counterparts due to resistance to this alternative approach. CLINICAL SIGNIFICANCE: Alternative antimicrobial approaches, as photodynamic therapy, should be encouraged due to optimal results against cariogenic bacteria aiming to prevent or treat dental caries.

Longitudinal effect of curcumin-photodynamic antimicrobial chemotherapy in adolescents during fixed orthodontic treatment: a single-blind randomized clinical trial study.

White spot lesions are one of the concerns during the fixed orthodontic treatment. Thus, the aim of the present study was to evaluate the antimicrobial/anti-inflammatory effect of curcumin-photodynamic antimicrobial chemotherapy (c-PACT) and chlorhexidine varnish on the plaque accumulation and gingival bleeding in adolescents under fixed orthodontic treatment. A randomized clinical trial was performed with an initial number of 45 patients being distributed into three groups: group I-chlorhexidine varnish 2%, group II-placebo varnish, and group III-c-PACT (curcumin at 1.5 mg.mL(-1)) exposed to blue Light-emitting diode (LED) light at 450 nm (power density = 165 mW.cm(-2), fluency = 96 J.cm(-2), total dose = 150.7 J). The treatments were performed for four consecutive times with an interval of 1 week each. After the interventions, two calibrated examiners (Kappa value = 0.75) analyzed the dental plaque accumulation by plaque index (PI) and gingivitis condition by gingival bleeding index (GBI) with 1 and 3 months of follow-up after the treatments comprised a final sample of 35 patients. No significant difference was found to PI between the groups during baseline and 1-month period. Group III (1.52 ± 0.51) presented significance difference from group I (0.91 ± 0.75) and group II (1.03 ± 0.51) at 3 months of follow-up. In this same period, there was more plaque accumulation with significant statistical difference (P ≤ 0.05) in comparison to the other periods to all studied groups. There was a GBI reduction statistically significant to groups I and III at 1-month follow-up in comparison to other periods. No effect was verified to dental plaque accumulation after the photodynamic application mediated with curcumin activated with a blue LED light.

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 to activate a nontoxic photosensitizing agent or dye in the presence of oxygen for eradication of target cells. In dentistry, this therapy is used to suppress the growth of microorganisms involved directly with dental decay and periodontitis process. There are evidences that curcumin dye is able to control microbial activity when illuminated with specific wavelength. The purpose of this study was to evaluate the in vitro efficacy of PDT using curcumin dye (Cur-C) in combination with a blue LED (L) device on a planktonic model of Streptococcus mutans (S. mutans). METHODS: Suspensions (0.5 mL) containing S. mutans at 1×10(7)CFU mL(-1) were prepared and divided 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 µM and 3 experimental conditions), Group C-L+ (LED at 3 different dosages: 24, 48 and 72 Jcm(-2) and 3 experimental conditions), and Group C+L+ (PDT group: curcumin at respective concentrations combined to LED dosages and 9 experimental conditions). Samples of each experimental condition were cultured in Petri dishes of BHI agar. Incubation in micro-aerophilia at 37°C for 48 h was performed for subsequent visual counting of CFU/mL. Data were transformed into log10 and analyzed by two-way ANOVA and Tukey's test at p<0.05. RESULTS: Group C+L+, in specific experimental conditions, demonstrated a log bacterial reduction 70% higher than Group C-L-. Both groups C-L+ and C+L- presented a slight decrease in log bacterial counting. CONCLUSION: This in vitro method was able to reduce the number of S. mutans in a planktonic suspension.

Antimicrobial photodynamic action on dentin using a light-emitting diode light source.

OBJECTIVE: The aim of this study was the evaluation of two different photosensitizers activated by red light emitted by light-emitting diodes (LEDs) in the decontamination of carious bovine dentin. MATERIALS AND METHODS: Fifteen bovine incisors were used to obtain dentin samples which were immersed in brain-heart infusion culture medium supplemented with 1% glucose, 2% sucrose, and 1% young primary culture of Lactobacillus acidophilus 10(8) CFU/mL and Streptococcus mutans 10(8) CFU/mL for caries induction. Three different concentrations of the Photogem solution, a hematoporphyrin derivative (1, 2, and 3 mg/mL) and two different concentrations of toluidine blue O (TBO), a basic dye (0.025 and 0.1 mg/mL) were used. To activate the photosensitizers two different light exposure times were used: 60 sec and 120 sec, corresponding respectively to the doses of 24 J/cm(2) and 48 J/cm(2). RESULTS: After counting the numbers of CFU per milligram of carious dentin, we observed that the use of LED energy in association with Photogem or TBO was effective for bacterial reduction in carious dentin, and that the greatest effect on S. mutans and L. acidophilus was obtained with TBO at 0.1 mg/mL and a dose of 48 J/cm(2). It was also observed that the overall toxicity of TBO was higher than that of Photogem, and that the phototoxicity of TBO was higher than that of Photogem. CONCLUSION: Based on our data we propose a mathematical model for the photodynamic effect when different photosensitizer concentrations and light doses are used.