The effects of photobiomodulation using LED on the repair process of skin graft donor sites.

The benefits of photobiomodulation (PBM) applied to wounds are well-described in the literature; however, its effects in skin graft donor sites have been poorly studied. The aim of this study is to evaluate the effects of LED PBM on re-epithelialization and wound quality of the skin donor site and on pain during repair process. This is a case series study that part of the patients received standard treatment and the others received standard treatment combined with PBM. Data collection was performed at the Burn Unit at a Public Hospital, Brazil. The study had 21 participants and 25 donor sites, 13 in the control group (conventional treatment with Membracel® bandage) and 12 in the experimental group (Membracel® + LED). Irradiation parameters were 1.53 J/cm2, 2.55 mW/cm2, 660 nm, 600 s in the immediate postoperative period as well as on the 1st, 3rd, 5th, and 7th days postoperatively. Pain was measured using the visual analog scale. The Bates-Jensen scale was used to monitor the re-epithelialization process and measurements were performed of donor skin sites in the postoperative period. Quantitative variables were expressed as mean ± standard deviation or median and interquartile range [p25; p75]. The comparison of the distribution of these variables between groups was performed using the Mann-Whitney test. No differences between groups were found for re-epithelialization time, area or quality of the wound. Regarding pain, a significant reduction was found on the 5th postoperative day in the experimental group compared to the control group. PBM did not induce changes in the re-epithelialization period, wound area or wound quality scores of the Bates-Jensen Scale but did induce a reduction in pain compared to the group treated with Membracel® alone.

Study protocol for the use of photobiomodulation with red or infrared LED on waist circumference reduction: a randomised, double-blind clinical trial.

INTRODUCTION: The search for non-invasive procedures to reduce localised adiposity in aesthetics clinics has recently been increasing. In this context, procedures, such as cryolipolysis, ultracavitation, photobiomodulation (PBM) and other techniques have been proposed. Some studies have shown that PBM can be used in body contouring. However, there is no standardisation of the protocol. More than that, as in other techniques for reducing adipose tissue, the availability of triacylglycerol may affect the lipid profile in the blood, bringing consequences to the general health of an individual. This work will aim to compare the light wavelengths when using PBM as a technique for reducing the abdominal waist circumference, while also evaluating the efficacy of the method. Changes in the lipid profile in the blood, with a long-term follow-up, will also be appraised. METHODS AND ANALYSIS: This will be a controlled, randomised, double-blind, single-centred clinical trial. 174 patients will be recruited at the Nove de Julho University, Brazil, and then divided into three groups: Group A-RED PBM; Group B-INFRARED PBM; Group C-PLACEBO (Sham) treatment. The treatments will consist of eight sessions, two times a week, for 4 weeks. At each session, the participants will receive 30 minutes PBM (using a radiant exposure of 127 J/cm2), with an abdominal strap containing 4 LED clusters, with 72 devices each, following the indication of randomisation. All of the groups will receive 30 min of Aussie Current, at 4 kHz, modulated at 10 Hz, 40-60 mA. The main outcome of this study will be waist circumference reduction. The secondary variables will be anthropometric data, lipid profile, liver function and adipose tissue thickness, changes in the local microcirculation, and the quality of life and self-esteem. The analyses will be performed at four stages of the research, D0, end of the eighth session (D30), 15 days after the last session (FU15), 90 days after the last session (FU90) and 180 days after the last session (FU180). ETHICS AND DISSEMINATION: The Ethics Committee of the Nove de Julho University, Brazil, approved the modified version of this project under No. 3414146 on 26 June 2019. This study is not yet recruiting. The results obtained will be published in a peer-reviewed journal in the related field. TRIAL REGISTRATION NUMBER: Brazilian Registry of Clinical Trials-ReBec (RBR-9bwxcx).

Antimicrobial photodynamic therapy with Bixa orellana extract and blue LED in the reduction of halitosis-A randomized, controlled clinical trial.

BACKGROUND: This study aimed to evaluate the reduction of halitosis when using antimicrobial photodynamic therapy (aPDT) with Bixa orellana extract and blue light-emitting diode (LED). METHODS: Forty-four UNINOVE students or employees with a diagnosis of sulfide (H2S) ≥ 112 ppb in gas chromatography were selected. The patients were randomly divided in groups: Group 1 (n = 15): aPDT with annatto and LED; Group 2 (n = 14): tongue scraping; Group 3 (n = 15): tongue scraping and aPDT. For aPDT, a wasBixa orellana extract used in a concentration of 20 % w/v (Fórmula e Ação®, São Paulo, Brazil) on the tongue for 2 min, associated with a blue-violet LED (Valo Cordless Ultradent® Products, Inc., South Jordan, UT, USA) (395-480 nm). Six points were irradiated on the back of the tongue, at wavelength 395-480 nm for 20 s, energy of 9.6 J and radiant energy of 6.37 J/cm2 per point. The results were compared before, immediately after treatment and 7 days after. The Friedman test was used for the intragroup analysis and the Kruskal Wallis test for the intergroup analysis. RESULTS: In all groups, there was a difference between baseline and the value immediately after the treatment. In Groups 1 and 3, there was no difference between the baseline and the 7 days control. CONCLUSION: There was an immediate reduction of halitosis, but the reduction was not maintained after 7days.

Therapy for patients with burns - an integrating review.

OBJECTIVE: to identify, through an integrative review, national studies published over the last ten years highlighting products and therapies used in burns. METHODS: integrative research with studies published in the last ten years. Including clinical studies describing the use of the already established or innovative therapies in burns and the results obtained, published in national journals in the last ten years. Excluding articles published before 2007 and those that did not present results regarding the use of products in burns. RESULTS: ten articles that met the inclusion criteria were selected. Collagenase, 1% silver sulfadiazine, and porous cellulose membrane were some of the therapies cited. CONCLUSION: the casuistry was low; however, the good results obtained with porous cellulose membrane and silver nanocrystalline dressing are highlighted, since they were used in a larger number of patients in the studies evaluated.

Microleakage of "Bulk-Fill" Composite Resin for Class II Restorations Pretreated With CO2 Laser in Deciduous Molars: An In Vitro Study.

Introduction: Microleakage has been reported to cause dentin hypersensitivity because of the passage of bacteria and their products through the restoration-tooth interface and is one of the main reasons for replacement of restorations. CO2 laser can be used for treatment of dentin hypersensitivity. Thus, this study aimed to evaluate in vitro the microleakage in composite restorations following surface pretreatment with acid etching and CO2 laser. Methods: Twelve human caries-free primary molars were selected. Class II cavities were prepared on occlusal mesial and occlusal distal surfaces. Specimens were randomly divided into four groups (n=6): Group 1 (G1) - 37% phosphoric acid gel etching + Beautiful-Bulk Restorative - Giomer (Shofu Inc); Group 2 (G2) - 37% phosphoric acid gel etching + SDR Bulk-Fill Flow (Dentsply); Group 3 (G3) - CO2 laser irradiation + Beautiful-Bulk Restorative - Giomer (Shofu Inc); Group 4 (G4) - CO2 laser irradiation + SDR Bulk-Fill Flow (Dentsply). Surfaces were restored with bonding agent (Natural Bond DE, DFL). Specimens were cut longitudinally and immersed in 0.5% methylene blue solution for 4 hours. Microleakage scores were assessed under a magnifying glass at x3,5 and qualitatively analyzed by scanning electron microscope (SEM). Data were analyzed using nonparametric Wilcoxon test (P < 0.05). Results: Scores prevailed between 0 and 2, however, no statistically significant difference was found among the groups (P = 0.05). Conclusion: It could be concluded that all composite resins bulk fill did not show significant difference among them regarding microleakage using either CO2 laser or 37% phosphoric acid etching.

Therapy for patients with burns - an integrating review

SUMMARY OBJECTIVE: to identify, through an integrative review, national studies published over the last ten years highlighting products and therapies used in burns. METHODS: integrative research with studies published in the last ten years. Including clinical studies describing the use of the already established or innovative therapies in burns and the results obtained, published in national journals in the last ten years. Excluding articles published before 2007 and those that did not present results regarding the use of products in burns. RESULTS: ten articles that met the inclusion criteria were selected. Collagenase, 1% silver sulfadiazine, and porous cellulose membrane were some of the therapies cited. CONCLUSION: the casuistry was low; however, the good results obtained with porous cellulose membrane and silver nanocrystalline dressing are highlighted, since they were used in a larger number of patients in the studies evaluated.

RESUMO OBJETIVO: Identificar, por meio de revisão integrativa, estudos nacionais publicados nos últimos dez anos que destaquem produtos e terapêuticas utilizados nas queimaduras. MÉTODOS: Pesquisa integrativa com estudos publicados nos últimos dez anos. Incluídos os estudos clínicos que descreveram a utilização de terapias já consagradas ou inovadoras em queimaduras e os resultados obtidos e publicados em periódicos nacionais nos últimos dez anos. Excluídos os artigos publicados antes de 2007 e os que não apresentaram resultados quanto ao uso de produtos nas queimaduras. RESULTADOS: Selecionados dez artigos que atenderam aos critérios de inclusão, sendo colagenase, sulfadiazina de prata 1% e membrana celulósica porosa algumas das terapias descritas. CONCLUSÕES: A casuística foi baixa, porém, ressaltam-se os bons resultados obtidos com a membrana celulósica porosa e o curativo com prata nanocristalina, em virtude de terem sido utilizados em um maior número de pacientes nos estudos avaliados.

The effect of antimicrobial photodynamic therapy on infected dentin in primary teeth: A randomized controlled clinical trial protocol.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) has been used for the treatment of dental caries. Papacarie is a gel composed of papain and chloramine employed for the partial removal of carious tissue, effective against bacteria, however, some studies report that this antibacterial action is not quite so evident. The aim of this study is to evaluate the clinical effect of aPDT on infected dentin in dental caries lesion in primary teeth. METHODS: Thirty-two primary molars with deep occlusal dental caries will be selected and divided in 2 groups: G1 - caries removal with a low-speed drill and G2 - application of aPDT with PapacarieMBlue. After treatment, all the teeth will be restored with glass ionomer cement and followed up clinically and radiographically, with evaluations at 3, 6, and 12 months. Dentin samples before and after treatment will be analyzed microbiologically. The data will be submitted to descriptive statistical analysis of the association between the categorical variables and both age and gender using the chi-square test and Fisher exact text. The Student t test and analysis of variance will be used for the comparison of mean signs and symptoms of reversible pulpitis. Pearson correlation coefficients will be calculated for the analysis of correlations among the continuous variables. DISCUSSION: Adding methylene blue dye to the formula of PapacarieMBlue might potentiate the antimicrobial action of aPDT and work more effectively on the infected dentin combined with a conservative, minimally invasive treatment. TRIAL REGISTRATION: NCT02734420 on 10 march 2016.

Photodynamic therapy with Bixa orellana extract and LED for the reduction of halitosis: study protocol for a randomized, microbiological and clinical trial.

BACKGROUND: Halitosis is an unpleasant breath odour that can interfere with the professional life, social life and quality of life of people who suffer from it. A modality of treatment that has been increasing in dentistry is antimicrobial photodynamic therapy (aPDT). Bixa orellana, popularly known as "urucum" is a plant native to Brazil. The seeds are used to produce a dye that is largely used in the food, textile, paint and cosmetic industries. The aim of this study is to verify whether aPDT with Bixa orellana extract and blue light-emitting diodes (LEDs) is effective in reducing halitosis. This method will also be compared with tongue scraping, the most commonly used conventional method for tongue coating removal, and the association of both methods will be evaluated. METHODS/DESIGN: A randomized clinical trial will be conducted at the dental clinic of the Universidade Nove de Julho. Thirty-nine patients will be divided by block randomization into three groups (n = 13) according to the treatment to be performed. In Group 1, tongue scraping will be performed by the same operator in all patients for analysis of the immediate results. Patients will also be instructed on how to use the scraper at home. Group 2 will be treated with aPDT with Bixa orellana extract and the LED light curing device: Valo Cordless Ultradent®. Six points in the tongue dorsum with a distance of 1 cm between them will be irradiated. The apparatus will be pre-calibrated at wavelength 395-480 nm for 20 s and 9.6 J per point. In Group 3, patients will be submitted to the tongue scraping procedure, as well as to the previously explained aPDT. Oral air collection with the Oral Chroma™ and microbiological collections of the tongue coating shall be done before, immediately after and 7 days after treatment for comparison. DISCUSSION: Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using blue LEDs for treating halitosis on a daily basis, as most dentists already have this light source in their offices. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03346460 . Registered on 17 November 2017.

Administration of low-level laser on muscles of mastication following the induction of initial fatigue: protocol for a randomized, controlled, clinical trial.

BACKGROUND: Orofacial pain encompasses painful conditions, such as temporomandibular disorder (TMD). Multidisciplinary health teams seek to control such musculoskeletal disorders to improve the quality and functional capacity of the muscles of mastication. The aim of the proposed study is to evaluate the effect of low-level laser therapy as a form of treatment for the prevention of initial fatigue of the muscles of mastication (masseter and anterior temporal muscles) as well as the recovery of these muscles after induced exhaustion (caused by isometric contraction) in young adults. METHODS: The participants will be 78 healthy male and female volunteers between 18 and 34 years of age. The volunteers will be randomly allocated to a laser group (n = 26), sham group (n = 26), and control group (n = 26). All participants will be submitted to a clinical evaluation to record mandibular movements, bite force, muscle sensitivity to palpation, and initial muscle fatigue. Initial fatigue will be induced by isometric contraction of the jaws. Maximum voluntary contraction will be performed to record the time until initial exhaustion of the masseter muscle (determined by electromyography). The groups will then be submitted to the interventions: active laser therapy (wavelength: 780 nm; fluence: 134 J/cm; power: 50 mW; irradiance: 1.675 W/cm; exposure time: 80 seconds per point) on 3 points of the masseter and 1 point on the anterior temporal muscles on each side; sham laser (placebo effect); or no intervention (control). Maximum voluntary contraction will be performed again after the interventions to record the time until initial exhaustion of the masseter muscle (determined by electromyography). Differences in individual time until exhaustion between the pre- and postintervention evaluations will be measured to determine the effect of low-level laser therapy. DISCUSSION: Although studies have been made with the use of low-level laser therapy in TMDs and on the effect of photobiomodulation on fatigue, this the first study to test this therapy in the prevention of fatigue in this region. The clinical relevance lies in the fact that longer dental procedures could take place if the patients are less prone to fatigue.

Effect of led photobiomodulation on analgesia during labor: Study protocol for a randomized clinical trial.

BACKGROUND: Labor pain is one of the most intense pains experienced by women, which leads to an increase in the number of women opting to undergo a cesarean delivery. Pharmacological and nonpharmacological analgesia methods are used to control labor pain. Epidural analgesia is the most commonly used pharmacological analgesia method. However, it may have side effects on the fetus and the mother. Light-emitting diode (LED) photobiomodulation is an effective and noninvasive alternative to pharmacological methods. OBJECTIVES: To evaluate the effects of LED photobiomodulation on analgesia during labor. METHODS: In total, 60 women in labor admitted to a public maternity hospital will be selected for a randomized controlled trial. The participants will be randomized into 2 groups: intervention group [analgesia with LED therapy (n = 30)] and control group [analgesia with bath therapy (n = 30)]. The perception of pain will be assessed using the visual analogue scale (VAS), with a score from 0 to 10 at baseline, that is, before the intervention. In both the groups, the procedures will last 10 minutes and will be performed at 3 time points during labor: during cervical dilation of 4 to 5 cm, 6 to 7 cm, and 8 to 9 cm. At all 3 time points, pain perception will be evaluated using VAS shortly after the intervention. In addition, the evaluation of membrane characteristics (intact or damaged), heart rate, uterine dynamics, and cardiotocography will be performed at all time points. EXPECTED OUTCOMES: The use of LED photobiomodulation will have an analgesic effect superior to that of the bath therapy.

Evaluation of low-level laser at auriculotherapy points to reduce postoperative pain in inferior third molar surgery: study protocol for a randomized controlled trial.

BACKGROUND: A comfortable postoperative return to daily activities has increased the need to control inflammation after third molar surgery. Anti-inflammatory drugs and analgesics are not exempt from adverse effects such as allergies and chronic gastritis, and they are not without cost. The association between low-level laser and auricular acupuncture can be an alternative when conventional drugs are contraindicated. Among its advantages, we can mention the low risk of side effects, low cost and simplicity of application. The objective of this study is to evaluate the efficiency of low-level laser at auriculotherapy points in reducing postoperative pain in lower third molar surgery. METHODS/DESIGN: Ninety bilateral, symmetrical lower third molar surgeries will be performed in 45 healthy patients. Each patient will be their own control, through a split-mouth crossover study. One side of the mouth will be randomly chosen and, immediately after surgery, will be treated with low-level laser. After 21 days, the contralateral side will be operated on with low-level laser simulation used postoperatively. This regimen (laser application or not) will be repeated at 24 and 48 h after surgery. All patients will be requested to take analgesics (acetaminophen) if they have pain, i.e. in case of pain. Neither the surgeon nor the patients will know the assigned treatment. The primary variable will be postoperative pain assessed using a Visual Analog Scale, and the secondary variables will be trismus, edema, local temperature, dysphagia, presence of infection and painkiller ingestion. These variables will be assessed at baseline, 24 h, 48 h and 7 days after surgery. Blood samples for systemic inflammatory cytokine (TNF-α, IL-1, IL-6 and IL-8) analysis will be assessed at baseline and 24 h after surgery. DISCUSSION: Some authors believe that using a wavelength of 633 to 670 nm is a good option for laser therapy in the field of acupuncture. This wavelength can penetrate biological tissue to a depth of about 3 mm. However, for auriculotherapy points, the stimulus (mustard seeds, needles 1 to 2.5 mm) does not penetrate so deeply. For this reason, we chose a laser wavelength of 660 nm (red wavelength). TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02657174 , registered on 11 January 2016.

Photobiomodulation of the dorsal root ganglion for the treatment of low back pain: A pilot study.

BACKGROUND AND OBJECTIVE: Chronic low back pain is a worldwide public health issue with high socioeconomic impact. The aim of this study was to determine the efficacy of laser irradiation of the dorsal root ganglion of the second lumbar spinal nerve for chronic axial low back pain compared to lidocaine injection and radiofrequency treatment. STUDY DESIGN/MATERIALS AND METHODS: Twenty-eight patients were randomly divided into three treatment groups: lidocaine injection, radiofrequency, or laser. The second intervertebral foramen between the second and third lumbar vertebrae was accessed by percutaneous needle puncture bilaterally, guided by fluoroscopy. In the local anesthetic group, injection of 1 ml lidocaine without epinephrine was applied through a 20-gauge (G20) Quincke tip spinal needle inserted in the second lumbar intervertebral foramen. In the radiofrequency group, the probe (150 mm long with a 5 mm active tip) was directed through a G20 needle placed in the second lumbar intervertebral foramen and neuromodulation was done with a radiofrequency of Cosman G4® in pulses of 20 ms with wash-out period of 480 ms, for 300 seconds at 42°C. A single treatment was used. In the laser treatment group, a continuous wave, 808 nm wavelength diode laser (Photon Lase III® DCM, Brazil), with an output power of 100 mW was used for a single treatment. An 18 gauge needle was placed in the second lumbar intervertebral foramen guided by fluoroscopy. Light was delivered through a 600 µm optical fiber placed in the G18 needle. The tip of the fiber extended 5 mm beyond the tip of the needle in the second lumbar intervertebral foramen. The beam spot size was 0.003 cm(2) , irradiance = 35W/cm(2) , exposure time = 84 seconds, energy density = 2800J/cm(2) , total energy was 8.4 J. The low back pain score was assessed by the visual analog scale (VAS) and Pain Relief Scale (PRS) pre, post procedure and in 1 month follow up. Temperature was measured using a digital thermometer. RESULTS: All patients in the local anesthetic and laser treatment groups reported a pain reduction of at least 50% immediately post-procedure and 10 out of 11 patients in the radiofrequency group reported a pain reduction of at least 50%. At 1 month post-treatment, the laser treatment group had the greatest number of patients who reported more than 50% pain relief based on PRS (7 out of 10 patients) while only 2 out of 7 patients and 3 out of 11 patients in the lidocaine and radiofrequency treatment groups respectively reported more than a 50% pain relief. CONCLUSION: Laser irradiation caused an immediate decrease in low back pain post-procedure similar to pain reduction caused by lidocaine injection. Both lidocaine injection and laser irradiation were more effective than radiofrequency treatment for immediate and longer term (1 month post-treatment) chronic back pain. Lasers Surg. Med. 48:653-659, 2016. © 2016 Wiley Periodicals, Inc.

Fully automated algorithm for wound surface area assessment.

Worldwide, clinicians, dentists, nurses, researchers, and other health professionals need to monitor the wound healing progress and to quantify the rate of wound closure. The aim of this study is to demonstrate, step by step, a fully automated numerical method to estimate the size of the wound and the percentage damaged relative to the body surface area (BSA) in images, without the requirement for human intervention. We included the formula for BSA in rats in the algorithm. The methodology was validated in experimental wounds and human ulcers and was compared with the analysis of an experienced pathologist, with good agreement. Therefore, this algorithm is suitable for experimental wounds and burns and human ulcers, as they have a high contrast with adjacent normal skin.

The influence of red laser irradiation timeline on burn healing in rats.

Low-level laser therapy (LLLT) promotes biomodulation of wound healing and literature reports that light delivery during the inflammation could play a different role compared with latter phases of the healing process. The objective of this study was to investigate whether single dose of a red laser (λ = 660 nm) is different from fractionated delivery protocol in full thickness burns. Two lesions were inflicted on the back of 36 rats. In the fractionated dose group (FG), the lesions were irradiated with 1 J/cm² on days 1, 3, 8, and 10 post-wounding. In the single dose group (SG), the lesions were irradiated with 4 J/cm² on day 1, immediately after injury. Control lesions (CG) received no light and were left to heal spontaneously. Blood flow was measured on days 1, 3, 8, 10, 15, and 21 using laser Doppler flowmetry. Animals were killed on days 3, 8, 10, 15, and 21. Skin specimens were obtained and routinely processed for hematoxylin and eosin. The specimens were evaluated according to differential leukocyte counting and angiogenesis. Statistical analysis was performed, and significance was accepted at p < 0.05. Irradiated groups showed a peak of new vessels on day 15 while, for CG, the peak was on day 21. On day 21, FG exhibited a significantly greater number of cumulative neutrophils while SG showed a higher number of mononuclear cells. Our results confirm that both protocols used accelerate angiogenesis and stimulate leukocyte chemotaxis on burn treatment. In addition, this work suggests that a single-dose LLLT accelerates the inflammatory phase of skin repair.

Birefringence and second harmonic generation on tendon collagen following red linearly polarized laser irradiation.

Regarding the importance of type I collagen in understanding the mechanical properties of a range of tissues, there is still a gap in our knowledge of how proteins perform such work. There is consensus in literature that the mechanical characteristics of a tissue are primarily determined by the organization of its molecules. The purpose of this study was to characterize the organization of non-irradiated and irradiated type I collagen. Irradiation was performed with a linearly polarized HeNe laser (λ = 632.8 nm) and characterization was undertaken using polarized light microscopy to investigate the birefringence and second harmonic generation to analyze nonlinear susceptibility. Rats received laser irradiation (P = 6.0 mW, I = 21.2 mW/cm(2), E ≈ 0.3 J, ED = 1.0 J/cm(2)) on their healthy Achilles tendons, which after were extracted to prepare the specimens. Our results show that irradiated samples present higher birefringence and greater non-linear susceptibility than non-irradiated samples. Under studied conditions, we propose that a red laser with polarization direction aligned in parallel to the tendon long axis promotes further alignment on the ordered healthy collagen fibrils towards the electric field incident. Thus, prospects for biomedical applications for laser polarized radiation on type I collagen are encouraging since it supports greater tissue organization.

Effective transmission of light for media culture, plates and tubes.

The results of many investigations on low-level laser therapy are contradictory and this is due to the large number of illumination parameters as well as the inability to measure the possible effects after irradiation with the necessary objectivity and the fact that the light needs to pass thorough barriers (usually the plastic of the culture dish/plate and culture medium) to reach the cells. In this manner, the objective of this study was to determine the absorption coefficient, penetration depth and effective transmission in materials commonly used in cell cultures. Among the most commonly used wavelengths in low-level laser therapy, the lowest absorption coefficients were reached by DMEM and RPMI (α = 0.03 cm(-1)), from 633 to 690 nm, which reach an effective transmission of 93% of incident radiation and penetration depth of 33 cm. Among the solid materials in the same range of the electromagnetic spectrum, the lowest absorption coefficient was obtained for the polystyrene (Petri dish and well plate), with α = 1.31 cm(-1), 78% of effective transmission and 0.76 cm of penetration depth. This article also presents a simple equation for estimating the amount of energy that will actually reach the sample.

Effects of 1047-nm neodymium laser radiation on skin wound healing.

Previous research in our laboratory has shown that the polarization component of the electrical field plays an important role on the healing process of inflammatory lesions created in the end of the spinal column of Lewis rats, using a He-Ne laser at lambda = 632.8 nm. It is well known that polarization is lost in a turbid medium, such as living tissue. However, the Nd:YLF wavelength (lambda = 1,047 nm) allows more polarization preservation than lambda = 632.8 nm, and the Nd:YLF laser beam has been used in clinical trials as a biostimulating agent. In this work, we investigated the influence of a low-intensity, linearly polarized Nd:YLF laser beam on skin wound healing, considering two orthogonal directions of polarization. We have considered a preferential axis as the animals' spinal column, and we aligned the linear laser polarization first parallel, then perpendicular to this direction. Burns of about 6 mm in diameter were created with liquid N2 on the back of the animals, and the lesions were irradiated on days 3, 7, 10, and 14 postwounding, D = 1.0 J/cm2. Lesions 1 and 2 were illuminated using Nd:YLF pulsed laser radiation. Lesion 1 was irradiated with linear polarization parallel with the rat spinal column. Lesion 2 was irradiated using the same protocol, but the light polarization was aligned with the perpendicular relative orientation. Control lesions were not irradiated. We have taken photographs from the wound areas on the 3rd, 7th, 10th, 14th, and 17th postoperative day for a biometrical analysis. The results have shown that lesion 1 healed faster than the control lesions (p < 0,05), which presented a smaller degree of healing after 14 days postwounding.