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Abstract Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Clinical interest in BNCT has focused primarily on the treatment of high grade gliomas, recurrent cancers of the head and neck region and either primary or metastatic melanoma. Neutron sources for BNCT currently have been limited to specially modified nuclear reactors, which are or until the recent Japanese natural disaster, were available in Japan, United States, Finland and several other European countries, Argentina and Taiwan. Accelerators producing epithermal neutron beams also could be used for BNCT and these are being developed in several countries. It is anticipated that the first Japanese accelerator will be available for therapeutic use in 2013. The major hurdle for the design and synthesis of boron delivery agents has been the requirement for selective tumor targeting to achieve boron concentrations in the range of 20 μg/g. This would be sufficient to deliver therapeutic doses of radiation with minimal normal tissue toxicity. Two boron drugs have been used clinically, a dihydroxyboryl derivative of phenylalanine, referred to as boronophenylalanine or “BPA”, and sodium borocaptate or “BSH” (Na2B12H11SH). In this report we will provide an overview of other boron delivery agents that currently are under evaluation, neutron sources in use or under development for BNCT, clinical dosimetry, treatment planning, and finally a summary of previous and on-going clinical studies for high grade gliomas and recurrent tumors of the head and neck region. Promising results have been obtained with both groups of patients but these outcomes must be more rigorously evaluated in larger, possibly randomized clinical trials. Finally, we will summarize the critical issues that must be addressed if BNCT is to become a more widely established clinical modality for the treatment of those malignancies for which there currently are no good treatment options.

Abstract Background Boron neutron capture therapy (BNCT) is a selective radiotherapy, being effective for the treatment of even advanced malignancies in head and neck regions as well as brain tumors and skin melanomas. To clarify the role of p53 gene, the effect of BNCT on oral squamous cell carcinoma (SCC) cells showing either wild- (SAS/neo) or mutant-type (SAS/mp53) p53 was examined. Methods Cells were exposed to neutron beams in the presence of boronophenylalanine (BPA) at Kyoto University Research Reactor. Treated cells were monitored for modulations in colony formation, proliferation, cell cycle, and expression of cell cycle-associated proteins. Results When SAS/neo and SAS/mp53 cells were subjected to BNCT, more suppressive effects on colony formation and cell viability were observed in SAS/neo compared with SAS/mp53 cells. Cell cycle arrest at the G1 checkpoint was observed in SAS/neo, but not in SAS/mp53. Apoptotic cells increased from 6 h after BNCT in SAS/neo and 48 h in SAS/mp53 cells. The expression of p21 was induced in SAS/neo only, but G2 arrest-associated proteins including Wee1, cdc2, and cyclin B1 were altered in both cell lines. Conclusion These results indicate that oral SCC cells with mutant-type are more resistant to BNCT than those with wild-type p53, and that the lack of G1 arrest and related apoptosis may contribute to the resistance. At a physical dose affecting the cell cycle, BNCT inhibits oral SCC cells in p53-dependent and -independent manners.

Background: Antimicrobial photodymanic therapy mediated by methylene blue has been investigated as an adjunctive to periodontal treatment but the dimerization of photosensitizer molecules reduces the phototoxic effects. Sodium dodecyl sulfate is a surfactant that may control this aggregation. The aim of this study was evaluated the photodynamic effect of methylene blue in sodium dodecyl sulfate in periodontitis., Methods: 36 participants with periodontitis were selected and allocated randomly in two group for intervention and other two for control - all of them were treated with scaling and root planing before aPDT. Three periodontal evaluations were done: at the selection time, at the day of intervention and thirty-day after this. Pre-irradiation time was 1 min and 2 min for irradiation. Laser (Therapy XT, DMC, São Carlos, Brazil) with wavelength of 660 nm and 100 mW of power was used. Two photosensitizer solutions with 100 µM methylene blue was used, one of them was in water and other in 0,25% of sodium dodecyl sulfate. Two sites of each participant were selected for the experimental procedures. Microbiological evaluations were performed to quantify microorganisms before and immediately after intervention. Quantitative microbiological evaluation was the primary outcome; morphological aspects of bacterial colony, and clinical probing depth was the secondary one., Results: There was no significant difference between the groups in both bacterial reduction and the clinical parameter evaluated., Conclusion: The effect of methylene blue in surfactant did not cause enough phototoxic effects that could promote reduction of periodontal pocket depth., (Copyright © 2022. Published by Elsevier B.V.)

Gingival melanin pigmentation is present in many African and Oriental descendant people and its occurrence in patients may interfere with the absorption and scattering of therapeutic doses of light. Antimicrobial photodynamic therapy (aPDT) is used as an adjunctive treatment for periodontitis and light irradiation may be impaired by tissue size and its melanin content. The aim of this clinical study was to measure the red-light attenuation in gingival tissue naturally pigmented with melanin. Ten patients with melanized gingival tissue were selected and irradiated by 100 mW red laser. The patients were photographed in frontal and incisal regions with a T2i camera (Canon, Japan) with 100 mm macro lens, 35 mm focal length, aperture f22, 1/100 shutter speed and ISO 200. Three randomly selected sites of each patient were used for evaluations and the irradiation values were assessed in the IMAGEJ software (NIH, Wayne Rasband, USA). Intensity in pixels was quantified in relation to the distance from the light incident point. Data were normalized and the results were presented as relative light intensity as a function of distance. The results demonstrated that red laser light is exponentially attenuated as a function of lateral distance and loses approximately 50 % of its intensity by 2.23 mm. On the other hand, the light travels 3 mm in depth to decay 50 %. In conclusion, our data suggest that melanin presence decreases optical pathway and irradiation protocols for antimicrobial photodynamic therapy in gingival tissue should consider light attenuation and depth of periodontal pockets so that efficient illumination of the target tissue occurs. Periodontal pockets bigger than 6 mm should be irradiated with more than one point., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Periodontal disease (PD) is a chronic inflammatory disease caused by the presence of microbial biofilm. The aim of this study was to evaluate antimicrobial effect of antimicrobial photodynamic therapy (A-PDT) mediated by methylene blue (MB) in monomer form on A. actinomycetemcomitans and P. gingivalis., Methods: A. actinomycetemcomitans ATCC 29523 and P. gingivalis ATCC 33577 were cultured on anaerobic jars at 37 °C for 48 h, and we tested APDT in the presence of 0.25% sodium dodecyl sulfate (SDS) in phosphate-buffered saline (PBS) or in PBS alone. APDT was carried out with 100 μM MB under laser radiation (PhotolaseIII, DMC, Brazil) at ʎ =660 nm and parameters as following (P =100 mW; I =250 mW/cm 2 , and doses of 15, 45 and 75 J/cm 2 )., Results: Following A-PDT, PBS groups of A. actinomycetemcomitans presented 4 Logs of microbial death after 5 min irradiation. However, there was no bacterial reduction in SDS groups. On the other hand, P. gingivalis was sensitive to APDT in the presence of 0.25% SDS with 2 logs reduction from dark toxicity., Conclusion: The presence of 0.25% SDS can lead to different responses depending on the different microbial species., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Antimicrobial photodynamic therapy (aPDT) has been investigated as an adjunctive to periodontal treatment but the dosimetry parameters adopted have discrepancies and represent a challenge to measure efficacy. There is a need to understand the clinical parameters required to obtain antimicrobial effects by using aPDT in periodontal pockets. The aim of this study was to investigate parameters relating to the antimicrobial effects of photodynamic therapy in periodontal pockets., Material and Methods: This randomized controlled clinical trial included 30 patients with chronic periodontitis. Three incisors from each patient were selected and randomized for the experimental procedures. Microbiological evaluations were performed to quantify microorganisms before and after treatments and spectroscopy was used to identify methylene blue in the pocket. A laser source with emission of radiation at wavelength of ʎ = 660 nm and output radiant power of 100 mW was used for 1, 3 and 5 min. One hundred μM methylene blue was used in aqueous solution and on surfactant vehicle., Results: The results demonstrated the absence of any antimicrobial effect with aqueous methylene blue-mediated PDT. On the other hand, methylene blue in the surfactant vehicle produced microbial reduction in the group irradiated for 5 min (p < 0.05). Spectroscopy showed that surfactant vehicle decreased the dimer peak signal at 610 nm., Conclusion: Within the parameters used in this study, PDT mediated by methylene blue in a surfactant vehicle reached significant microbial reduction levels with 5 min of irradiation. The clinical use of PDT may be limited by factors that reduce the antimicrobial effect. Forms of irradiation and stability of the photosensitizers play an important role in clinical aPDT., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Antimicrobial photodynamic therapy (aPDT) has been used to treat periodontal disease, thus the aim of this study was to investigate red light (ʎ = 660 nm) attenuation in gingival tissue. This clinical trial included 30 patients with chronic periodontitis; three incisors from each patient were selected for the experimental procedures. A laser source with a radiant power output of 100 mW was used. Two digital photographs were taken of each selected incisor (in frontal and occlusal position). The images were analyzed in the ImageJ program. The results demonstrated that at a 3 mm distance from the laser probe, there is an attenuation of light intensity of 50%, along frontal and occlusal views. Light attenuation in gingival tissue should be considered when setting optimal parameters for antimicrobial photodynamic therapy or photobiomodulation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Localized surface plasmon resonance (LSPR) of gold nanoparticles has been reported to increase the antimicrobial effect of the photodynamic therapy. Although silver nanoparticles (AgNPs) are an efficient growth inhibitor of microorganisms, no studies exploring LSPR of AgNPs to enhance the photodynamic inactivation (PDI) have been related. In this work, we described the LSPR phenomenon of AgNP sand investigated its interaction with riboflavin, a natural photosensitizer. We evaluated the use of AgNPs coated with pectin (p-AgNP) in riboflavin (Rb)-mediated PDI of Escherichia coli (Gram- bacteria) and Streptococcus mutans (Gram + bacteria) using a blue light-emitting diode (λ = 455 ± 20 nm) of optical power 200 mW. Irradiance was 90 mW/cm 2 and radiant exposure varied according to the time exposure. Uptake of Rb and p-AgNP by the cells was evaluated by measuring the supernatant absorption spectra of the samples. We observed that LSPR of p-AgNPs was able to enhance the riboflavin photodynamic action on S. mutans but not on E. coli, probably due to the lower uptake of Rb by E. coli. Taken together, our results provide insights to explore the use of the LPRS promoted by silver nanostructures to optimize antimicrobial PDI protocols., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Dental caries are a multifactorial disease that progressively produces tooth destruction as a result of bacterial colonization of enamel surface, especially Streptococcus mutans. The objective of this work was to investigate the role of glucose in antimicrobial photodynamic therapy (aPDT) on S. mutans., Methods: S. mutans ATCC 25175 were cultured on microaerophilia at 37°C for 48h, and we tested aPDT in the presence of 50mM glucose. Bacterial suspension was used to investigate aPDT with 100μM methylene blue (MB) under LED emitting radiation at ʎ=660nm and parameters as following (P=473 mW; I=166.8 mW/cm 2 , and doses of 5, 10 and 20J/cm 2 ). A seventy-two hours biofilm was grown on 96 flat buttoned well-plate and irradiation was performed from 10 to 80J/cm 2 at similar conditions., Results: There was no dark toxicity nor bacterial death regarding LED irradiation on suspension and on biofilm. Nevertheless, aPDT presented expressive bacterial inactivation following 1 and 2min of irradiation on cell suspension. On the other hand, there was no inactivation in the presence of glucose under the same conditions. Biofilm was completely inactivated by MB-mediated aPDT after 6min of irradiation. However, the presence of glucose delayed the complete inactivation of the biofilm., Conclusion: The presence of glucose in the suspension drastically delayed the effect of aPDT on S. mutans and this effect is more pronounced in bacterial suspension than on biofilm., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Candida albicans biofilm is a main cause of infections associated with medical devices such as catheters, contact lens and artificial joint prosthesis. The current treatment comprises antifungal chemotherapy that presents low success rates. Photodynamic inactivation (PDI) involves the combination of a photosensitizing compound (PS) and light to generate oxidative stress that has demonstrated effective antimicrobial activity against a broad-spectrum of pathogens, including C. albicans. This fungus senses glucose inducing an upregulation of membrane transporters that can facilitate PS uptake into the cell. The aim of this study was to evaluate the effects of glucose on methylene blue (MB) uptake and its influence on PDI efficiency when combined to a red LED with central wavelength at λ=660nm. C. albicans biofilms were grown on hydrogel disks. Prior to PDI assays, MB uptake tests were performed with and without glucose-sensitization. In this system, the optimum PS administration was determined as 500μM of MB in contact with the biofilm during 30min before irradiation. Irradiation was performed during 3, 6, 9, 12, 15 and 18min with irradiance of 127.3mW/cm 2 . Our results showed that glucose was able to increase MB uptake in C. albicans cells. In addition, PDI without glucose showed a higher viability reduction until 6min; after 9min, glucose group demonstrated a significant decrease in cell viability when compared to glucose-free group. Taken together, our data suggest that glucose is capable to enhance MB uptake and modulate photodynamic inactivation of C. albicans biofilm., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The aim of this study was to assess the effectiveness of low intensity laser therapy in patients with Burning Mouth Syndrome (BMS). Thirty BMS subjects were randomized into two groups - Laser (LG) and Placebo (CG). Seven patients dropped out, leaving 13 patients in LG and 10 patients in CG. Each patient received 4 irradiations (laser or placebo) twice a week, for two consecutive weeks (blinded to the type of irradiation received). Infrared laser (AsGaAI) irradiations were applied to the affected mucosa in scanning mode, wavelength of 790 nm, output power of 20 mW and fluence of 6 J/cm2. A visual analogue scale (VAS) was used to assess the therapeutic effect before and after each irradiation, and at all the control time periods: 7, 14, 30, 60 and 90 days after the last irradiation. One researcher delivered irradiation and another recorded the results. Both researchers were blinded, the first to the results, and the second to the type of radiation applied. The results were categorized according to the percentage of symptom level variation, and showed a statistically better response in LG in only two categories of the control checkpoints (p=0.02; Fisher's Exact Test). According to the protocol used in this study, low intensity laser therapy is as beneficial to patients with BMS as placebo treatment, indicating a great emotional component of involvement in BMS symptomatology. Nevertheless, there were positive results in some statistical analyses, thus encouraging further research in BMS laser therapy with other irradiation parameters.

Antimicrobial photodynamic therapy (APDI) has been used to treat localized infection and the aim of this study was to evaluate the effect of APDI combined with fluconazole in suspension of Candida albicans. C. albicans ATCC90028 was subcultured onto Sabouraud agar and inocula were prepared at yeast density of 1×10(6)CFU/mL. Methylene blue (MB) was used with concentration of 100mM. Yeast cells were incubated for 30min in 24-well plate and then irradiated by LED (660nm; 690mW; A=2.7cm(2); I=250mW/cm(2)) with radiant exposure of 30, 60, and 120J/cm(2). The same APDI setup was used with 2h fluconazole (0.5μg/mL) incubation. A UV-vis optical absorption spectroscopy was achieved following fractionated irradiation up to 960s. There were substantial differences in the killing effect following MB-mediated APDI and C. albicans was eradicated in the both APDI groups. The fluconazole combined to APDI delayed the complete inactivation of the yeast (p<0.05). Spectroscopy showed a decrease in absorption following irradiation for all absorption peaks. APDI presented an antagonist effect in the presence of fluconazole., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this study, we looked at the possible effects of low-level laser therapy (LLLT) on blood flow velocity, and serotonin (5-HT) and cholinesterase levels in patients with chronic headache associated with temporomandibular disorders (TMD). LLLT has been clinically applied over the past years with positive results in analgesia and without the report of any side effects. The understanding of biological mechanisms of action may improve clinical results and facilitate its indication. Ten patients presenting headache associated with TMD completed the study. An 830-nm infrared diode laser with power of 100 mW, exposure time of 34 s, and energy of 3.4 J was applied on the tender points of masseter and temporal muscle. Blood flow velocity was determined via ultrasound Doppler velocimetry before and after laser irradiation. The whole blood 5-HT and cholinesterase levels were evaluated three days before, immediately, and three days after laser irradiation. Pain score after treatment decreased to a score of 5.8 corresponding to 64% of pain reduction (P < 0.05). LLLT promoted a decrease in the blood flow velocity (P < 0.05). In addition, the 5-HT levels were significantly increased three days after LLLT (P < 0.05). The cholinesterase levels remained unchanged at the analyzed time points (P > 0.05). Our findings indicated that LLLT regulates blood flow in the temporal artery after irradiation and might control 5-HT levels in patients suffering with tension-type headache associated to TMD contributing to pain relief., (© 2016 by the Society for Experimental Biology and Medicine.)

Background: The purpose of this study was to evaluate the antibacterial effects of photodynamic action of methylene blue (MB) against Aggregatibacter actinomycetemcomitans organized on biofilm., Methods: After the biofilm growth in 96 flat-bottom well plate, the following groups were used: control group, untreated by either laser or photosensitizer (PS); MB group or dark toxicity group, which was exposed to MB alone (100μM) for 1min (pre-irradiation time); laser group, irradiated with laser for 5min in the absence of PS and three antimicrobial photodynamic inactivation (APDI) groups, with three exposure times of 1, 3 and 5min of irradiation, corresponding to fluences of 15, 45, and 75J/cm(2) respectively. The results were compared to the control group for statistical proposes. Scanning electronic microscope analysis was used to access structural changes in biofilm., Results: Red laser alone and MB alone were not able to inactivate bacterial biofilm. APDI groups showed differences when compared to the control group and they were dependent on the exposure time. No statistically significant differences were observed among the APDI groups at 1 and 3min of irradiation. On the other hand, 5min of APDI showed 99.85% of bacterial reduction (p=0.0004). In addition, the biofilm loose its structure following 5min APDI., Conclusions: The results of this study suggest that A. actinomycetemcomitans biofilm can be inactivated by MB mediated APDI., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Semiconductor colloidal quantum dots (QDs) have been applied in biological analysis due to their unique optical properties and their versatility to be conjugated to biomolecules, such as lectins and antibodies, acquiring specificity to label a variety of targets. Concanavalin A (Con A) lectin binds specifically to α-d-mannose and α-d-glucose regions of saccharides that are usually expressed on membranes of mammalian cells and on cell walls of microbials. Candida albicans is the most common fungal opportunistic pathogen present in humans. Therefore, in this work, this fungus was chosen as a model for understanding cells and biofilm-forming organisms. Here, we report an efficient bioconjugation process to bind CdTe (Cadmium Telluride) QDs to Con A, and applied the bioconjugates to label saccharide structures on the cellular surface of C. albicans suspensions and biofilms. By accomplishing hemagglutination experiments and circular dichroism, we observed that the Con A structure and biochemical properties were preserved after the bioconjugation. Fluorescence microscopy images of yeasts and hyphae cells, as well as biofilms, incubated with QDs-(Con A) showed a bright orange fluorescence profile, indicating that the cell walls were specifically labeled. Furthermore, flow cytometry measurements confirmed that over 93% of the yeast cells were successfully labeled by QD-(Con A) complex. In contrast, non-conjugated QDs or QDs-(inhibited Con A) do not label any kind of biological system tested, indicating that the bioconjugation was specific and efficient. The staining pattern of the cells and biofilms demonstrate that QDs were effectively bioconjugated to Con A with specific labeling of saccharide-rich structures on C. albicans. Consequently, this work opens new possibilities to monitor glucose and mannose molecules through fluorescence techniques, which can help to optimize phototherapy protocols for this kind of fungus., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Vaginal candidiasis (VC) is a disease that affects thousands of women of childbearing age, mainly caused by Candida albicans fungus. Photodynamic therapy (PDT) uses photosensitizing substances that are nontoxic in the dark, but able to produce reactive oxygen species when they are subjected to a light source. In this work our purpose was to investigate PDT effects on fungal burden and inflammatory cells in a murine model of C. albicans-induced vaginal candidiasis., Methods: Female BALB/c mice 6-10 weeks were estrogenized and maintained in this state during all experiment. After 72h, mices were inoculated intravaginally (IV) with 20μL of 2×10(5)C. albicans cells suspension. Mice were separated into 5 groups after five days: H (healthy), PBS (control), laser, MB (methylene blue) and PDT. PDT and MB groups received IV 20μL solution with 1mM of MB, others received PBS. PDT and laser groups were irradiated with a red laser (100mW, 660nm) in one (36J, 6min) or two sessions (18J, 3min). After the end of treatment, mice were submitted to microbiological and histomorphometric analysis with ImageJ software. Data were plotted by mean values and standard deviations of CFU/mL and percentage of inflammatory cells area. ANOVA and Bonferroni post-test were used and data were considered significant when p<0.05., Results: PDT significantly reduced C. albicans after the two tested protocols, however, percentage area of inflammatory cells was significantly reduced just with two sessions of PDT., Conclusions: PDT with MB and red laser is a promising therapy for VC. It is able to reduce fungal infection in biofilm and inflammatory signals associated with VC in a murine model of vaginitis., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Antimicrobial photodynamic therapy (APDT) may become a useful clinical tool to treat microbial infections, and methylene blue (MB) is a well-known photosensitizer constantly employed in APDT studies, and although MB presents good efficiency in antimicrobial studies, some of the MB photochemical characteristics still have to be evaluated in terms of APDT. This work aimed to evaluate the role of MB solvent's ionic strength regarding dimerization, photochemistry, and photodynamic antimicrobial efficiency. Microbiological survival fraction assays on Escherichia coli were employed to verify the solution's influence on MB antimicrobial activity. MB was evaluated in deionized water and 0.9% saline solution through optical absorption spectroscopy; the solutions were also analysed via dissolved oxygen availability and reactive oxygen species (ROS) production. Our results show that bacterial reduction was increased in deionized water. Also we demonstrated that saline solution presents less oxygen availability than water, the dimer/monomer ratio for MB in saline is smaller than in water and MB presented a higher production of ROS in water than in 0.9% saline. Together, our results indicate the importance of the ionic strength in the photodynamic effectiveness and point out that this variable must be taken into account to design antimicrobial studies and to evaluate similar studies that might present conflicting results.

Opportunistic fungal pathogens may cause an array of superficial infections or serious invasive infections, especially in immunocompromised patients. Cryptococcus neoformans is a pathogen causing cryptococcosis in HIV/AIDS patients, but treatment is limited due to the relative lack of potent antifungal agents. Photodynamic inactivation (PDI) uses the combination of non-toxic dyes called photosensitizers and harmless visible light, which produces singlet oxygen and other reactive oxygen species that produce cell inactivation and death. We report the use of five structurally unrelated photosensitizers (methylene blue, Rose Bengal, selenium derivative of a Nile blue dye, a cationic fullerene and a conjugate between poly-L-lysine and chlorin(e6)) combined with appropriate wavelengths of light to inactivate C. neoformans. Mutants lacking capsule and laccase, and culture conditions that favoured melanin production were used to probe the mechanisms of PDI and the effect of virulence factors. The presence of cell wall, laccase and melanin tended to protect against PDI, but the choice of the appropriate photosensitizers and dosimetry was able to overcome this resistance.

The objective of this study was to evaluate whether Candida albicans exhibits altered pathogenicity characteristics following sublethal antimicrobial photodynamic inactivation (APDI) and if such alterations are maintained in the daughter cells. C. albicans was exposed to sublethal APDI by using methylene blue (MB) as a photosensitizer (0.05 mM) combined with a GaAlAs diode laser (λ 660 nm, 75 mW/cm(2), 9 to 27 J/cm(2)). In vitro, we evaluated APDI effects on C. albicans growth, germ tube formation, sensitivity to oxidative and osmotic stress, cell wall integrity, and fluconazole susceptibility. In vivo, we evaluated C. albicans pathogenicity with a mouse model of systemic infection. Animal survival was evaluated daily. Sublethal MB-mediated APDI reduced the growth rate and the ability of C. albicans to form germ tubes compared to untreated cells (P < 0.05). Survival of mice systemically infected with C. albicans pretreated with APDI was significantly increased compared to mice infected with untreated yeast (P < 0.05). APDI increased C. albicans sensitivity to sodium dodecyl sulfate, caffeine, and hydrogen peroxide. The MIC for fluconazole for C. albicans was also reduced following sublethal MB-mediated APDI. However, none of those pathogenic parameters was altered in daughter cells of C. albicans submitted to APDI. These data suggest that APDI may inhibit virulence factors and reduce in vivo pathogenicity of C. albicans. The absence of alterations in daughter cells indicates that APDI effects are transitory. The MIC reduction for fluconazole following APDI suggests that this antifungal could be combined with APDI to treat C. albicans infections.

In this study we developed a rat model of incipient caries to investigate the short-term effects of antimicrobial photodynamic therapy (aPDT) on oral microbiota regulation and demineralization arrestment. Twenty-nine male rats were submitted to caries induction. Early carious lesion was confirmed by optical coherence tomography (OCT) 5 days after experiment beginning in five animals. The remaining animals (n = 24) were randomly divided into two groups: control (n = 12), animals were untreated; and aPDT (n = 12), animals were treated with 100 μM of methylene blue for 5 min and irradiated by a light emitting diode at λ = 645 ± 30 nm, fluence rate of 480 mW cm(-2) and exposure time of 3 min. Bacterial burden was evaluated before, immediately after, 3, 7 and 10 days following treatment, and total number of microaerophilic bacteria was counted. OCT was also used to quantify teeth demineralization. A significant bacterial decrease of about 1.6 log was observed immediately after aPDT. Besides, bacterial load in aPDT group remained lower than control until 10 days post-treatment (P < 0.05) and variation of optical attenuation coefficient before and after aPDT was 15%, corroborating to caries arrestment. Put together, these findings suggest that aPDT was competent to reduce cariogenic bacteria and to avoid further mineral loss., (© 2011 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2011 The American Society of Photobiology.)

Pseudomonas aeruginosa is considered one of the most important pathogens that represent life-threatening risk in nosocomial environments, mainly in patients with severe burns. Antimicrobial photodynamic therapy (aPDT) has been effective to kill bacteria. The purpose of this study was to develop a burn wound and bloodstream infection model and verify aPDT effects on it. In vitro, we tested two wavelengths (blue and red LEDs) on a clinical isolate of P. aeruginosa strain with resistance to multiple antibiotics using HB:La(+3) as photosensitizer. Verapamil(®) associated to aPDT was also studied. In vivo, P. aeruginosa-infected burned mice were submitted to aPDT. Bacterial counting was performed on local infection and bloodstream. Survival time of animals was also monitored. In this study, aPDT was effective to reduce P. aeruginosa in vitro. In addition, Verapamil(®) assay showed that HB:La(+3) is not recognized by ATP-binding cassete (ABC) efflux pump mechanism. In the in vivo study, aPDT was able to reduce bacterial load in burn wounds, delay bacteremia and keep the bacterial levels in blood 2-3 logs lower compared with an untreated group. Mice survival was increased on 24 h. Thus, this result suggests that aPDT may also be a novel prophylactic treatment in the care of burned patients., (© 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.)

Objectives: To investigate whether the major fungal multidrug efflux systems (MESs) affect the efficiency of methylene blue (MB)-mediated antimicrobial photodynamic inactivation (APDI) in pathogenic fungi and test specific inhibitors of these efflux systems to potentiate APDI., Methods: Candida albicans wild-type and mutants that overexpressed two classes of MESs [ATP-binding cassette (ABC) and major facilitator superfamily (MFS)] were tested for APDI using MB as the photosensitizer with and without addition of MES inhibitors. The uptake and cytoplasm localization of photosensitizer were achieved using laser confocal microscopy., Results: ABC MES overexpression reduced MB accumulation and APDI killing more than MFS MES overexpression. Furthermore, by combining MB APDI with the ABC inhibitor verapamil, fungal killing and MB uptake were potentiated, while by combining MB APDI with the MFS inhibitor INF(271), fungal killing and MB uptake were inhibited. This latter surprising finding may be explained by the hypothesis that the MFS channel can also serve as an uptake mechanism for MB., Conclusions: The ABC pumps are directly implicated in MB efflux from the cell cytoplasm. Both the influx and efflux of MB may be regulated by MFS systems, and blocking this gate before incubation with MB can decrease the uptake and APDI effects. An ABC inhibitor could be usefully combined with MB APDI for treating C. albicans infections.

Objective: The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on the treatment of burning mouth syndrome (BMS). In addition, the laser effect was compared on the different affected oral sites., Materials and Methods: Eleven subjects with a total of 25 sites (tongue, lower lip, upper lip, and palate) affected by a burning sensation were selected. The affected areas were irradiated once a week for three consecutive weeks with an infrared laser (λ = 790 nm). The probe was kept in contact with the tissue, and the mucosal surface was scanned during the irradiation. The exposure time was calculated based on the fluence of 6 J/cm(2), the output power of 120 mW, and the area to be treated. Burning intensity was recorded through a visual analog scale before and after the treatment and at the 6-week follow-up. The percentage of the improvement in symptoms was also obtained., Results: Burning intensity at the end of the laser therapy was statistically lower than at the beginning (p < 0.01). Patients reported an 80.4% reduction in the intensity of symptoms after laser treatment. There was no statistical difference between the end of the treatment and the 6-week follow-up, except for the tongue site., Conclusion: Under the investigated parameters, infrared LLLT proved to be a valuable alternative for BMS treatment, providing a significant and lasting reduction in symptoms.

Objective: The aim of this study was to investigate the effects of 960 nm diode laser and acidulated phosphate fluoride on calcium solubility of human dental enamel., Background Data: Interest in diode lasers has grown steadily since its invention due to its inherent advantages and its range of applications. Several other laser types have shown good results in caries prevention; however, there are few studies on dental tissue interactions using diode lasers., Methods: Acid resistance was evaluated using 65 enamel specimens, divided into five groups: control (C), fluoride (F), laser (L), laser + fluoride (LF), and fluoride + laser (FL). The laser was operated using the parameters of 6.5-W peak power, 5-msec pulse duration, 10-Hz repetition rate, and 33-mJ pulse energy. These parameters were previously tested regarding pulpal temperature rise and enamel morphology, and were determined to be safe. The amount of calcium lost during demineralization was measured., Results: The calcium solubility of the laser group was 12% higher than of the control group (p > 0.05). Group F showed a 33.6% increase of acid resistance (p < 0.05). When laser was associated with fluoride, the calcium solubility increased significantly (p < 0.05) compared to both the control group and the laser group. Groups treated with fluoride showed the same results (p > 0.05)., Conclusion: The 960-nm diode laser promoted a slight increase in calcium solubility. A statistically significant reduction on calcium solubility was achieved with the three treatments that involve fluoride (F, FL, and LF). The additional application of laser irradiation did not cause any significant increase or decrease in calcium solubility.

Objective: This in vitro study examines the efficacy of two different dental whitening agents, Opalescence Xtra and Opus White, by analyzing the change in color achieved by the treatment and the temperature increase induced in the pulpal chamber., Background Data: Bleaching techniques achieved significant advances with the use of coherent or incoherent radiation sources to activate the bleaching chemicals., Methods: The bleaching agents, containing 35% of hydrogen peroxide, were stimulated with 0.9 W of xenon arc lamp and 0.9 W or 2 W of a 960-nm diode laser during 60 sec (0.9 W) and 30 sec (2 W) on 33 extracted human teeth. During irradiation, the temperature in the pulpal cavity was monitored. The color change was evaluated using the CIE L*a*b* color space measurement system., Results: The treated groups showed an increase in color saturation (DeltaC*) of 3-32% and a change in whiteness (DeltaL*) of 0-8%. This study found that only some of the irradiated groups show statistically significant difference (p < 0.05) in the effectiveness of their treatment when compared to the control, whereas no significant statistical difference was obtained in between the irradiated groups. Temperature increase was 2-4 degrees C when using the xenon arc lamp, 2-8 degrees C and 4-12 degrees C when using the diode laser at 0.9 W and 2 W, respectively., Conclusions: The results of this study suggest that Opalescence Extra and Opus White are both effective to provide brighter teeth. However, according to the conditions used in this study, only the xenon arc lamp induced a safer temperature increase.