Antimicrobial photodynamic therapy mediated by methylene blue in surfactant vehicle as adjuvant to periodontal treatment. Randomized, controlled, double-blind clinical trial.

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.

Melanin pigmented gingival tissue impairs red-light lateral scattering for antimicrobial photodynamic therapy.

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.

Antimicrobial photodynamic therapy mediated by methylene blue in surfactant vehicle on periodontopathogens.

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/cm2, and doses of 15, 45 and 75 J/cm2). 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.