Photodynamic therapy (PDT) is a technique that involves the activation of photosensitizers by light in the presence of oxygen, resulting in the production of reactive radicals that are capable of inducing cell death. The present study evaluated the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to PDT grown as multi-species in the biofilm phase versus in dentine carious lesions. A brainheart infusion culture medium supplemented with 1 % glucose, 2 % sucrose, and 1 % young primary culture of L. acidophilus 10 8 CFU/mL and S. mutans 10 8 CFU/mL was used to develop multi-species biofilms and to induce caries on human dentine slabs. Five different concentrations of curcumin (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were used associated with 5.7 J/cm 2 light emission diode. Four different groups were analyzed L−D− (control group), L−D+ (drug group), L+D− (light group), and L+D+ (PDT group). ANOVA/Tukey's tests were conducted to compare groups. A significant reduction (p <0.05) in cell viability was observed in the biofilm phase following photosensitization with all curcumin concentrations tested. To achieve significant bacterial reduction (p <0.05) in carious dentine, it was necessary to utilize 5.0 g/L of curcumin in association with blue light. No significant reduction was found for L−D+, supporting the absence of the drug's dark toxicity. S. mutans and L. acidophilus were susceptible to curcumin in the presence of blue light. However, due to light penetration and drug diffusion difficulties, these microorganisms within dentine carious lesions were less affected than they were in the biofilm phase.
Background data: Photodynamic therapy is a technique that involves the activation of photosensitizers by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. Objective: The present study assessed the overall susceptibility of pathogens of salivary flora to photodynamic therapy after sensitization with curcumin and exposure to blue light at 450 nm. Methods: A randomized trial was executed with 13 adult volunteers. Three different groups were analyzed: L-D-(no light, no drug; control group), L-D + (treated only with the drug; curcumin group) and L + D + (treated with drug and light; photodynamic therapy group). Non-stimulated saliva samples were collected for bacterial counts at baseline and after the experimental phase, and adverse events experienced were recorded. Serial dilutions were performed, and the resulting samples were cultured on blood agar plates in microaerophilic conditions. The number of colonyforming units was then determined. Results: There was a considerable difference between the two experimental groups with regard to effectiveness of bacterial reduction. In the L-D + group, the bacterial decline was considerably smaller (9%) than in the L + D + group, with a 68% decrease in bacteria. A statistically significant reduction in the bacterial population was observed only in the photodynamic therapy group ( p < 0.05). Conclusions: Photodynamic therapy was found to be effective in the reduction of salivary microorganisms. No significant reduction was found for the group in which only curcumin was used, proving the absence of dark toxicity of the drug. This work shows that overall disinfection of the mouth can be done with a simple procedure involving photodynamic action.
Background data: The presence of Streptococcus mutans and Lactobacillus acidophilus in dental structure is an indicator of a cariogenic biofilm. Photodynamic therapy is a technique that involves the activation of photosensitizers by light in the presence of oxygen, resulting in the production of reactive radicals capable of inducing cell death. Reduction of bacteria levels can provide additional means of preventing dental caries. Objective: The present study evaluated the susceptibility of planktonic cultures of S. mutans (ATCC 25175) and L. acidophilus (ATCC-IAL-523) from the Adolfo Lutz Institute (IAL) to photodynamic therapy after sensitization with curcumin and exposure to blue light at 450 nm. Methods: Bacterial suspensions of S. mutans and L. acidophilus isolated (as single species) and combined (multspecies) were prepared and then evaluated. Four different groups were analyzed: L-D-(control group), L-D + (drug group), L + D-(light group), and L + D + (photodynamic therapy group). Two different concentrations of curcumin were tested (0.75 and 1.5 g/L) associated with a 5.7 J/cm 2 light emission diode. Results: Significant decreases ( p < 0.05) in the viability of S. mutans were only observed when the bacterial suspensions were exposed to both curcumin and light. Then, reductions in viability of up to 99.99% were observed when using 1.5 g/L of the photosensitizer. The susceptibility of L. acidophilus was considerably lower (21% and 37.6%) for both curcumin concentrations. Conclusions: Photodynamic therapy was found to be effective in reducing S. mutans and L. acidophilus on planktonic cultures. No significant reduction was found for L-D + , proving the absence of dark toxicity of the drug.
Although some remineralizing products provided microhardness recovery and a positive effect on enamel morphology at 24 h post-bleaching, none of them were able to maintain microhardness and enamel morphology at 14 days post-bleaching.
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