An endotracheal tube (ETT) is required for the management of critically ill, mechanically ventilated patients. Ventilatorassociated pneumonia (VAP) affects patients hospitalized in intensive care units; its risk of occurrence is 1% to up 3% for each day of mechanical ventilation. The polymicrobial nature of VAP is established with mixed bacterial-fungal biofilms colonizing the ETT. The microbial interaction enhances the microbial pathogenesis contributing to high indexes of morbidity/mortality. Antimicrobial Photodynamic Therapy (aPDT) could be a suitable therapy for decontamination of oral cavity and ETT at the same time, but the use of a fiber optics inside the ETT seems to not be appropriated since a cannula for secretion aspiration has to be introduced into the ETT to keep it´s lumen. The aim of this study is to proof the concept that an external light source from a LED is capable of reach all areas of the ETT. We use a commercial ETT, 60μM methylene blue (MB), and a 660nm diode laser and calculated the transmission coefficient of light in different situations as only tube, tube with biofilm and biofilm+MB. The results prove that is possible to transmit light through the tube even in the presence of MB and biofilm although a high attenuation of about 60% was measured depending on the tested condition.
Diabetes Mellitus is a chronic disease that can lead to lower-limb ulceration. The photodynamic therapy (PDT) is based on light interaction with a photosensitizer capable to promote bacterial death and tissue repair acceleration. This study analyzed the effects of PDT in the repair of human diabetic ulcers, by means of microbiological assessment. The clinical study was composed of 12 patients of both sexes with diabetic ulcers in lower limbs that were divided into two groups, control group (n=6) and PDT group (n=6). All patients were treated with collagenase/chloramphenicol during the experimental period, in which 6 of them have received PDT with methylene blue dye (0.01%) associated with laser therapy (660 nm), dose of 6 J/cm<sup>2¨</sup> and 30 mW laser power. PDT group received ten treatment sessions. Wounds were evaluated for micro-organisms analysis. It was found a reduction in the occurrence of Staphylococcus aureus in both groups, being that reduction more pronounced in the PDT group. Microbial count was performed on PDT group, showing a statistical difference reduction (p<0.05) when compared before and after the treatment. It is concluded that PDT seems to be effective in microbial reduction of human diabetic wounds, promoting acceleration and improvement of tissue repair quality.ty.
The aim of this study was to evaluate the enamel demineralization around cavities prepared by Er,Cr:YSGG laser (2780 nm) and restored with different materials after an acid challenge. The human dental enamel samples were randomly divided in 12 groups (n=10): G1- high-speed drill (HD); G2- Er,Cr:YSGG laser L (3 W, 20 Hz, 53.05 J/cm<sup>2</sup>)(air 65% - water 55%); G3– L (4 W, 20 Hz, 70.74 J/cm<sup>2</sup>); G4– L (5 W, 20 Hz, 88.43 J/cm<sup>2</sup>). Each group was divided in subgroups: 1- glass ionomer cement (GIC), 2- resin modified GIC (RMGIC), 3- composite resin (C). Samples were submitted to an acid challenge (4.8 pH) for7 days. The calcium ion contend (ppm/mm<sup>2</sup>) from demineralizing solutions were analyzed by atomic emission spectrometry. ANOVA and LSD tests were performed (α=5%). The significant lower average values of calcium loss were observed on G2 + GIC, G2 + RMGIC, G1 + RMGIC (p<0.05); the significant higher values were observed on G1 + C, G4 +GIC, G4 + C (p<0.05). The composite resin showed higher calcium loss than RMGIC and GIC (p<0.05). The lased cavities using lower fluence (53.05J/cm<sup>2</sup>) showed significant reduced demineralization than higher fluences (70.74 and 88.43J/cm<sup>2</sup>) (p<0.05). Neither the techniques nor the restorative materials used were able to avoid the enamel demineralization. The findings of this in vitro study suggest that the Er,Cr:YSGG lased cavities restored with GIC or RMGIC or conventional drill cavities with RMGIC were effective on reducing the demineralization around restorations, showing an important potential in preventing secondary caries.
The reduction of pathogenic microorganisms in supragingival plaque is one of the principal factors in caries prevention
and control. A large number of microorganisms have been reported to be inactivated in vitro by photodynamic therapy
(PDT). The purpose of this study was to develop a rat model to investigate the effects of PDT on bacterial reduction in
induced dental caries. Twenty four rats were orally inoculated with <i>Streptococcus mutans</i> cells (ATCC 25175) for three
consecutive days. The animals were fed with a cariogenic diet and water with 10% of sucrose ad libitum, during all
experimental period. Caries lesion formation was confirmed by Optical Coherence Tomography (OCT) 5 days after the
beginning of the experiment. Then, the animals were randomly divided into two groups: Control Group: twelve animals
were untreated by either light or photosensitizer; and PDT Group: twelve animals were treated with 100μM of methylene
blue for 5min and irradiated by a Light Emitting Diode (LED) at λ = 640±30nm, fluence of 172J/cm<sup>2</sup>, output power of
240mW, and exposure time of 3min. Microbiological samples were collected before, immediately after, 3, 7 and 10 days
after treatment and the number of total microaerophiles was counted. OCT images showed areas of enamel
demineralization on rat molars. Microbiological analysis showed a significant bacterial reduction after PDT.
Furthermore, the number of total microaerophiles in PDT group remained lower than control group until 10 days posttreatment.
These findings suggest that PDT could be an alternative approach to reduce bacteria in dental caries.