Interstitial PDT using diffuser fiber-investigation in phantom and in vivo models.

Photodynamic therapy (PDT) has been used for local treatment of several types of tumors. Light penetration of biological tissue is one limiting factor in PDT, decreasing the success rates of the treatment of invasive and solid tumors. In those cases, a possible solution is to use interstitial PDT, in which both diffuser optical fibers are inserted into the tumor. The uniformity of the diffuser emission plays a crucial role in planning the delivery of the appropriate light fluence and in ensuring treatment success. In this study, we characterized a diffuser optical fiber concerning its homogeneity. We showed that the diffuser emission can be inhomogeneous and that the necrosis generated by interstitial PDT using such a diffuser for illumination is asymmetrical in volume as a result. This observation has relevant consequences in achieving success in PDT and phototherapies in general, as the delivered light fluence depends on adequate previous knowledge of the irradiation profile.

A Multicenter Clinical Study of Expected and Unexpected Side Reactions During and After Skin Cancer Treatment by Photodynamic Therapy.

Photodynamic therapy (PDT) has been widely used for oncologic indications, especially nonmelanoma skin cancer such as superficial and nodular basal cell carcinoma (BCC). We present a multicenter clinical study conducted between 2012 and 2014 analyzing the adverse reactions during and after PDT with a standardized protocol in 866 lesions. A total of 728 patients with positive clinical and histopathological diagnosis for BCC with up to 2 cm diameter were treated. The procedure consisted of curettage and topical application of cream containing 20% methyl 5-aminolevulinate. The illumination (630 nm and 150 J/cm2) was performed 3 hours after the cream application. The expected and unexpected effects observed were pain, healing, and inflammatory reactions. The pain intensity was correlated with the anatomical localization of the lesion. The patients reported a higher intensity of pain in lesions located on the head and neck rather than on the trunk and limbs. The number of sessions also influenced the pain response. A total of 83% of patients showed perfect healing and the other 17% presented abnormal healing. PDT plays an important role in BCC because of its low cost, ease of use, and low rate of side effects.

Photodynamic therapy: Progress toward a scientific and clinical network in Latin America.

Cancer is one of the major challenges for Latin America health services, since the skin cancer is the most frequent lesion. This manuscript addresses an initiative for the treatment of basal cell carcinomas (BCC) by photodynamic therapy (PDT) based on a government-funded national program in Brazil. The program provides clinical training and facilitates access to drugs/equipment and significantly reduces PDT costs. It also lays foundations for the establishment of a Latin American research network to improve prevention, early detection and treatment of diseases. Centers have been established by direct contact (conferences, visits to healthcare facilities and official departments). A local training was divided into complementary theoretical and practical parts. This is an ongoing project that has involved 10 countries: Brazil, Bolivia Chile, Ecuador, El Salvador, Colombia, Cuba, Mexico, Peru and Venezuela, The initial results are encouraging and have provided assessment of Latin America patients relating, for example, the most common skin phototypes with incidence of BCC in such countries. The network is expected to produce relevant scientific information for PDT introduction in many countries. The experience acquired by local teams shall enable them to innovate PDT protocols and increase the number of skilled contributors/researchers to broaden knowledge on the ever-crescent PDT field in Latin America. The establishment of a collaboration network and introduction of other projects and experience exchange shall become an easier process with time. This PDT clinical research network is a start for the strengthening of Science in South Hemisphere countries.

Experience and BCC subtypes as determinants of MAL-PDT response: preliminary results of a national Brazilian project.

Non-melanoma skin cancer is the most prevalent cancer type in Brazil and worldwide. Photodynamic therapy (PDT) is a noninvasive technique with excellent cosmetic outcome and good curative results, when used for the initial stages of skin cancer. A Brazilian program was established to determine the efficacy of methyl aminolevulinate (MAL)-PDT, using Brazilian device and drug. The equipment is a dual device that combines the photodiagnosis, based on widefield fluorescence, and the treatment at 630nm. A protocol was defined for the treatment of basal cell carcinoma with 20% MAL cream application. The program also involves the training of the medical teams at different Brazilian regions, and with distinct facilities and previous PDT education. In this report we present the partial results of 27 centers with 366 treated BCC lesions in 294 patients. A complete response (CR) was observed in 76.5% (280/366). The better response was observed for superficial BCC, with CR 160 lesions (80.4%), when compared with nodular or pigmented BCC. Experienced centers presented CR of 85.8% and 90.6% for superficial and nodular BCC respectively. A high influence of the previous doctor experience on the CR values was observed, especially due to a better tumor selection.

LED light attenuation through human dentin: a first step toward pulp photobiomodulation after cavity preparation.

PURPOSE: To evaluate the transdentinal light attenuation of LED at three wavelengths through different dentin thicknesses, simulating cavity preparations of different depths. METHODS: Forty-two dentin discs of three thicknesses (0.2, 0.5 and 1 mm; n = 14) were prepared from the coronal dentin of extracted sound human molars. The discs were illuminated with a LED light at three wavelengths (450+/-10 nm, 630 +/-10 nm and 850 +/-10 nm) to determine light attenuation. Light transmittance was also measured by spectrophotometry. RESULTS: In terms of minimum (0.2 mm) and maximum (1.0 mm) dentin thicknesses, the percentage of light attenuation varied from 49.3% to 69.9% for blue light, 42.9% to 58.5% for red light and 39.3% to 46.8% for infrared. For transmittance values, an increase was observed for all thicknesses according to greater wavelengths, and the largest variation occurred for the 0.2 mm thickness. All three wavelengths were able to pass through the dentin barrier at different thicknesses. Furthermore, the LED power loss and transmittance showed wide variations, depending on dentin thickness and wavelength.

Photodynamic therapy for the treatment of induced mammary tumor in rats.

The objective of this work was to evaluate photodynamic therapy (PDT) by using a hematoporphyrin derivative as a photosensitizer and light-emitting diodes (LEDs) as light source in induced mammary tumors of Sprague-Dawley (SD) rats. Twenty SD rats with mammary tumors induced by DMBA were used. Animals were divided into four groups: control (G1), PDT only (G2), surgical removal of tumor (G3), and submitted to PDT immediately after surgical removal of tumor (G4). Tumors were measured over 6 weeks. Lesions and surgical were LEDs lighted up (200 J/cm(2) dose). The light distribution in vivo study used two additional animals without mammary tumors. In the control group, the average growth of tumor diameter was approximately 0.40 cm/week. While for PDT group, a growth of less than 0.15 cm/week was observed, suggesting significant delay in tumor growth. Therefore, only partial irradiation of the tumors occurred with a reduction in development, but without elimination. Animals in G4 had no tumor recurrence during the 12 weeks, after chemical induction, when compared with G3 animals that showed 60 % recurrence rate after 12 weeks of chemical induction. PDT used in the experimental model of mammary tumor as a single therapy was effective in reducing tumor development, so the surgery associated with PDT is a safe and efficient destruction of residual tumor, preventing recurrence of the tumor.

Ablation of composite resins using Er:YAG laser--comparison with enamel and dentin.

OBJECTIVES: The purpose of this work is to investigate comparative ablation rate between composite resins and dental hard tissues (enamel and dentin) after Er:YAG laser irradiation to verify possible development of an ultra-conservative dentistry to with minimum effect for the teeth tissue. METHODS: We have used 11 extracted or exfoliated primary anterior and posterior teeth and six extracted permanent molar teeth. Three different types of composite resin were chosen (microfiller, hybrid, and condensable) in terms of chemical and structural composition. Composite tablets and the teeth were irradiated with a Er:YAG laser at different laser beam energy level per pulse (100, 200, 300, and 400 mJ). Diameter and depth of each resulted microcavity were measured and the material removed volumes were calculated. The resulted values were plotted and fitted to allow a comparative observation of the material removed as a function of energy level per pulse. RESULTS: While the idea of ultra-conservative dentistry seems to apply well for enamel of primary and permanent teeth, at the present stage it does not apply well for primary or permanent dentin. For dentin, the composition and content of water makes the Er:YAG laser ablation equal or superior in rate compared with the three used resins. SIGNIFICANCE: This work presents of a comparative study of Er:YAG laser ablation, allowing to analyze the possible selective ablation between composite resin placed and cured and dental hard tissues, with the goal to propose a new clinical technique: differential ablation for composite resin restorations using Er:YAG laser.

Ablation rate and micromorphological aspects with Nd:YAG picosecond pulsed laser on primary teeth.

BACKGROUND AND OBJECTIVES: We have investigated the fundamental aspects of Nd:YAG laser at the picosecond pulse regime interacting with primary teeth. Because little is present in the literature concerning specific laser ablation for primary teeth with respect to enamel and dentin, this work may open perspectives for new investigations. STUDY DESIGN/MATERIALS AND METHODS: Using a picosecond Nd:YAG laser, different power levels (200, 300, and 350 mW) and different exposition times (5, 10, and 15 seconds) were considered. RESULTS: Micro-morphological aspects of the laser-tooth interaction showed collateral effects in enamel more accentuated than in dentin. Penetration depth in dentin seems to scale up in rate as the time of application progress, for enamel the behavior is the opposite. The overall ablated volume is higher in dentin when compared with enamel, which results in a higher ablated rate as well. CONCLUSIONS: Specific ablation characteristics are observed in either dentin or enamel.