Photodynamic inactivation (PDI) is described as a promising therapy for oral inactivation. Due to the low aqueous solubility of curcumin, appropriate delivery systems are required to facilitate its use as a photosensitizer. This study evaluated the effectiveness of on Streptococcus mutans biofilm using curcumin-loaded Pluronic® 127. The micelles were characterized by different techniques. MIC and MBC were determined, and after that the cell viability of the biofilm irradiated by blue LED was obtained by CFU/mL and by confocal microscopy. Curcumin-loaded Pluronic® F-127 micelles can be a viable alternative for curcumin to improve the water solubility and the antimicrobial photodynamic effect.
Streptococcus mutans is recognized as the major causative agent of dental caries, especially in fissures and on smooth surfaces. Thus, the purpose of this study was to evaluate the susceptibility of S. mutans (ATCC 25175) biofilm to photodynamic therapy after sensitization with chlorin e-6 (PS) at 0.6 and 2.5μM by exposure to red light at 660nm (BioTable®) under 36.1mW, 15J/cm2 and 5 min of pre-irradiation time. Biofilm was induced in BHI broth supplemented with 1% sucrose for 7 days in a 96 well-plate. Serial dilutions were seeded onto brain heart infusion agar to determine viability in colony-forming units per milliliter (CFU/mL). Additionally, the metabolism of the biofilm by XTT and confocal laser scanning microscopy (CLSM) was performed using BacLight LIVE/DEAD system. Different groups were analyzed: L-D- (negative control), L-D+ (drug), L+D- (light), L+D+ (PDT) and clhorexidine at 0.2% (positive control). Results were analyzed by two-way ANOVA and Tukey’s test (p<0.05). Biofilms were taken for observation at confocal microscopy, and qualitative analyzes were obtained as to the distribution of non-viable viable/cells using LIVE/DEAD® Baclight™ before and after treatments. For CFU/mL and metabolism, the data were submitted to analysis of variance (ANOVA) and Tukey's test at 5% significance. It was observed that there was statistically significant difference in all PDT and chlorhexidine Groups compared to negative control and light Group (p<0.05). No dark cytotoxicity was observed (p>0.05). PDT using chlorin e-6 as photosensitizer can be an adjunct and effective method to control Streptococcus mutans biofilm responsible to dental caries.
Dental biofilms are produced by bacterial communities. During the first 24 h of colonization, oral streptococci compose 60% to 90% of the supragingival plaque biomass. Mutans streptococci are biofilm-forming bacteria and are considered to be the primary etiologic agents of human dental caries. They possess a variety of abilities to colonize tooth surfaces and under certain conditions are present in large quantities in cariogenic biofilms and also form biofilms with other organisms, including other streptococci and bacteria. To reduce microbial, like biofilm, can be performed by using photodynamic therapy. Successful of this kind of therapy is induced by penetration of light and photosensitizer into target cells. The sonodynamic therapy offers greater penetrating capability into tissues. Then, the purpose of this study was to evaluate the antibacterial effect of photodynamic inactivation (PDI) associated with ultrasound (U) using curcumin solution irradiated by LED light source over Streptococcus mutans biofilm. Initially, minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were performed, The concentrations of 40 and 80 μM were selected for the next experiments. Streptococcus mutans biofilm were induced using a 96-well plates for 7 days according to Groups G1 (negative control, L0D0), G2 (L + U +), G3 (L + D0), G4 (L0D40-80), G5 (chlorhexidine, positive control), G6 (L + D40-80 U +), G7 (L + D40-80) and G8 (D40-80 U +). For the dark cytotoxicity, curcumin was incubated for 5 minutes. For PDI, the groups were incubated in the dark for 5minutes (pre-irradiation time) and irradiated by blue LED at 15J/cm2 (36mW/cm2) for 7minutes and 55seconds. Ultrasound was used for 5min under 0.16KW of power output and 1.5A (pre-irradiation). After treatment, the strains were seeded on BHI agar and incubated at 37°C for 48 hours to determine the number of CFU/mL. The results were transformed into log10 and submitted to analysis of variance (ANOVA) and Tukey test at the 5% level. Significant reductions in the number of viable cells of S. mutans were observed in groups G6 (6log10) providing 4log10 of bacterial reduction when compared to group G1 (2log10) (p <0.05). The association of PDI and ultrasound can be an effective method to control microorganisms in the oral cavity, especially S. mutans, which causes dental caries.
Dental caries is an infectious disease caused by acidogenic bacteria. Effective removal and/or inactivation of the cariogenic biofilm is crucial for the prevention and treatment of dental caries. Thus, the purpose of this study was to evaluate the susceptibility of S. mutans biofilm to photodynamic inactivation using two photosensitizers based on curcumin. Suspensions of S. mutans were exposed to LED at 440nm (BioTable®) under 36.1mW, 15J/cm2 and 5 min of pre-irradiation time with synthetic and commercial curcumin at different concentrations (160, 80, 40, 20, 10, 5, 2.5, 1.25, 0625 and 0.3μM) to determine minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC). After that, biofilm was induced for 7 days over hydroxyapatite discs (5mmx1.8mm). Serial dilutions were seeded onto BHI agar to determine viability by CFU/mL. Additionally, confocal laser scanning microscopy (CLSM) was performed using LIVE/DEAD® BacLight™ system to the distribution of non-viable viable/cells. Different Groups were analyzed: L-D- (negative control), L-D+ (drug Group), L+D- (light Group), L+D+ (PDI Group) and chlorhexidine at 0.2% (positive control). In addition, the mechanisms involved were determined before and after irradiation by absorption and fluorescence spectra. The results were analyzed by two-way ANOVA and Tukey’s test (p<0.05). Statistically significant difference in all PDI and chlorhexidine Groups compared to negative control and light Group (p<0.05) was observed. For the dark cytotoxicity, no significant difference was observed compared to the negative control Group (p>0.05). Photodynamic inactivation using curcumin can be an adjunct and effective method to control Streptococcus mutans biofilm responsible to dental caries.
We show that partial solubility of a photosensitizer is not necessarily a bad property when dealing with microbiological control. The presence of curcumin aggregates in solution may present advantages with respect the photoand chemical stability.
Human oral cavity is colonized by a wide range of microorganisms, often organized in biofilms. These biofilms are
responsible for the pathogenesis of caries and most periodontal diseases. A possible alternative to reduce biofilms is the photodynamic inactivation (PDI). The success of the PDI depends on different factors. The time required by the PS to remain in contact with the target cells prior to illumination is determinant for the technique’s efficacy. This study aimed to assess the interaction between the PS and the biofilm prior to the PDI.
We used confocal microscopy and FLIM to evaluate the interaction between the PS and the biofilm’s microorganism
during the pre-irradiation time (PIT). The study of this dynamics can lead to the understanding of why only some PSs are effective and why is necessary a long PIT for some microorganisms. Our results showed that are differences for each PIT. These differences can be the determinate for the efficacy of the PDI. We observed that the microorganism needs time to concentrate and/or transport the PS within the biofilm. We presented preliminary results for biofilms of Candida albicans and Streptococcus mutans in the presence of Curcumin and compared it with the literature. We observed that the effectiveness of the PDI might be directly correlated to the position of the PS with the biofilm. Further analyses will be conducted in order to confirm the potential of FLIM to assess the PS dynamics within the biofilms.
Some photosensitizers (PSs) used for PACT (Antimicrobial Photodynamic Therapy) show an affinity for bacterial walls
and can be photo-activated to cause the desired damage. However, on dentine bacterias may be less susceptible to PACT
as a result of limited penetration of the PS. The aim of this study was to evaluate the diffusion of one PS based on
hematoporphyrin on dentine structures. Twelve bovine incisors were used. Class III cavities (3 x 3 x 1mm) were
prepared on the mesial or distal surfaces using a diamond bur. Photogem® solution at 1 mg/mL (10 uL for each cavity)
was used. The experimental Groups were divided according to thickness of dentine remaining and etched or no-etched
before the PS application. The fluorescence excitation source was a VelScope® system. For image capture a scientific
CCD color camera PixelFly® was coupled to VelScope. For image acquisition and processing, a computational routine
was developed at Matlab®. Fick's Law was used to obtain the average diffusion coefficient of PS. Differences were
found between all Groups. The longitudinal temporal diffusion was influenced by the different times, thickness and acid
etching.
The use of composite resins for restorative procedure in anterior and posterior cavities is highly common in Dentistry
due to its mechanical and aesthetic properties that are compatible with the remaining dental structure. Thus, the aim of
this study was to evaluate the optical characterization of one dental composite resin using bovine enamel as reinforcing
filler. The same organic matrix of the commercially available resins was used for this experimental resin. The reinforcing
filler was obtained after the gridding of bovine enamel fragments and a superficial treatment was performed to allow the
adhesion of the filler particles with the organic matrix. Different optical images as fluorescence and reflectance were
performed to compare the experimental composite with the human teeth. The present experimental resin shows similar
optical properties compared with human teeth.
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