Cardiopulmonary and hematological effects of infrared LED photobiomodulation in the treatment of SARS-COV2.

BACKGROUND: COVID-19 disease is caused by SARS-CoV-2 which can trigger acute respiratory syndrome, which presents with dense alveolar and interstitial infiltrates and pulmonary edema, causing severe hypoxemia and significant alteration to pulmonary mechanics with reduced pulmonary compliance. The photobiomodulation technique alters cellular and molecular metabolism, showing promising results regarding the reduction of acute pulmonary inflammation. OBJECTIVE: To compare the photomodulation technique using near-infrared LED to conventional respiratory physiotherapy treatment in patients with COVID-19 in reversing acute conditions, reducing hospitalization time, and decreasing the need for oxygen therapy. METHODOLOGY: The cohort was comprised of 30 patients undergoing COVID-19 treatment who were divided and allocated into two equal groups randomly: the LED group (LED), treated with infrared LED at 940 nm and conventional therapy, and the control group (CON), who received conventional treatment (antibiotic therapy for preventing superimposed bacterial infections, and physiotherapy) with LED irradiation off. Phototherapy used a vest with an array of 300 LEDs (940 nm) mounted on a 36 cm × 58 cm area and positioned in the patient's anterior thoracic and abdominal regions. The total power was 6 W, with 15 min irradiation time. Cardiopulmonary functions and blood count were monitored before and after treatment. The patients were treated daily for 7 days. Statistical analysis was conducted using a two-tailed unpaired Student's t-test at a significance level of α = 0.05. RESULTS: Post-treatment, the LED group showed a reduction in hospital discharge time and a statistically significant improvement for the following cardiopulmonary functions: Partial Oxygen Saturation, Tidal Volume, Maximum Inspiratory, and Expiratory Pressures, Respiratory Frequency, Heart Rate, and Systolic Blood Pressure (p < 0.05). Regarding blood count, it was observed that post-treatment, the LED group presented with significant differences in the count of leukocytes, neutrophils, and lymphocytes. CONCLUSION: Photobiomodulation therapy can be used as a complement to conventional treatment of COVID-19, promoting the improvement of cardiopulmonary functions, and minimization of respiratory symptoms.

Analysis of pain relief and functional recovery in patients with rotator cuff tendinopathy through therapeutic ultrasound and photobiomodulation therapy: a comparative study.

This study aimed to compare shoulder tendinopathy treatment with therapeutic ultrasound combined with LED photobiomodulation therapy using LED-infrared (850 nm) or LED-red (640 nm). The study assessed 75 patients, aged 45 to 70 years, distributed into five experimental groups (15 patients each): therapeutic ultrasound (US), infrared light irradiation (IR), visible red light irradiation (VR), infrared light and ultrasound combined (IR-US), and red light in conjunction with ultrasound (VR-US). The ultrasound parameters are 1 MHz, 0.5 W/cm2 (SATA), and 100 Hz repetition rate, applied for 4 min each session. LED irradiation protocols were as follows: 3 points, 7.5 J per point, IR-LED 750 mW, 10 s, VR-LED 250 mW, 30 s. LED irradiation is followed by ultrasound in the combined therapies. The efficiency of the five therapies was evaluated assessing 12 parameters: quality of life (Health Assessment Questionnaire, HAQ), pain intensity (Visual Analog Scale, VAS), articular amplitude of shoulder movement (flexion, extension, abduction, adduction, medial rotation, lateral rotation), muscle strength (abduction, lateral rotation), and electromyography (lateral rotation, abduction). Treatments comprised 12 sessions for 4 weeks. Intra-group analysis showed that the five therapies significantly improved the recovery of all parameters after treatment. Regarding the comparison of irradiated therapies and ultrasound, statistical analysis showed that IR-US was a better treatment than US for all 12 parameters. IR treatment exceeded US on 9 items, whereas that VR and VR-US therapies exceeded US in 7 and 10 parameters, respectively (p < 0.05). Because of that, IR-US shows to be the best treatment for rotator cuff tendinopathy. In conclusion, improvements in quality of life, pain intensity relief, shoulder amplitude motion, and muscle strength force obtained with ultrasound therapy are enhanced by adding infrared LED irradiation to ultrasound for patients suffering from rotator cuff tendinopathy. This study was registered with the Brazilian Registry of Clinical Trials (ReBEC) under Universal Trial Number (UTN) U1111-1219-3594 (2018/22/08).

Systemic Effects of Photobiomodulation on Blood Components in the Treatment of Community-Acquired Pneumonia.

Background: The analysis of the complete blood count (CBC) of patients with community-acquired pneumonia (CAP) is an essential practice both for diagnosing the disease and for evaluating the patient's clinical evolution. It is proposed in the present study to analyze the hematological alterations resulting from photobiostimulation using near-infrared light-emitting diodes (LEDs) in patients with CAP. Methods: This was a clinical, prospective, blinded, and descriptive longitudinal study that involved 21 patients undergoing CAP treatment who were divided into two groups: LED, 11 patients who were treated with infrared LED and conventional treatment; and CON (control), 10 patients who received only conventional treatment (antibiotic therapy and physiotherapy). Physiotherapy was applied before LED irradiation in the LED group. The patients' CBCs were obtained before and after treatment, and erythrocyte counts, hemoglobin and hematocrit concentrations, and leukocyte and platelet counts were assessed. The phototherapy was performed with a vest with an array of 300 LEDs (940 nm) mounted on an area of 36 × 58 cm and positioned in the patient's anterior thoracic and abdominal regions. The total power was 6 W, with 15 min of irradiation time. The patients were treated daily for seven consecutive days. Statistical analyses of the intra- and intergroups of CBC data were done using Student's t-test and one-way ANOVA (analysis of variance), respectively, both at the significance level of α = 0.05. Results: There was a statistically significant recovery difference after treatment in the LED group compared with the CON group for erythrocytes, hemoglobin, leukocytes, segmented and band neutrophils, lymphocytes, and monocytes (p < 0.05). The greatest differences between the LED and CON groups were lymphocyte count reduction (60% vs. 16%), erythrocyte increase (86% vs. 35%), and leukocyte reduction (28% vs. 15%). Conclusions: The hematologic components of CAP patients recovered their normal values faster with conventional treatment associated with infrared LED therapy, thus indicating greater treatment efficiency when compared with the conventional therapy. This study was registered with the Brazilian Registry of Clinical Trials (ReBeC) under Universal Trial Number (UTN) U1111-1229-1296 (2019/06/05).

Use of photodynamic therapy in the treatment of bovine subclinical mastitis.

BACKGROUND: Bovine mastitis is a disease that causes a severe drawback in dairy production. Conventional treatments with antibiotic could leave antibiotic residues in the milk. The aim of this study was to evaluate the effect of photodynamic therapy in the treatment of bovine subclinical mastitis to develop an in vivo therapeutic protocol that could be used in routine farm practice, favoring the early return to production. METHODS: Forty cows with subclinical mastitis (n = 40) were divided into 4 groups (control, photodynamic therapy - PDT, light irradiation - LED, and photosensitizer - PS). Control group received no treatment, PDT group received application of 1.0 mL of 2.5% toluidine blue photosensitizer followed by LED irradiation at λ = 635 nm, the LED group was treated with LED irradiation alone, and the PS group received only 2.5% toluidine blue dye. LED irradiation was applied to the mammary gland by means of an acrylic light guide coupled to the LED equipment. The PDT and LED groups were irradiated with 200 J/cm2 at three different positions inside the mammary gland. Milk samples were collected at 0 h, 12 h, 24 h after treatment for microbial identification and total bacterial count. RESULTS: The treatment of the PDT group showed significant difference p < 0.05, characterizing the efficiency of this technique with the reduction of the microorganisms Streptococcus dysgalactiae and coagulase-negative Staphylococcus. CONCLUSION: Photodynamic therapy was effective when applied in vivo for subclinical bovine mastitis. There was no need to separate the animal from production.

Application of phototherapy for the healing of the navels of neonatal dairy calves.

The present work evaluated the effects of LED light irradiation on the healing of the navels of neonatal dairy calves. Fifty-seven neonatal calves were divided into two groups. Animals had their umbilical stumps immersed in 10% iodine tincture for 60 s, and this process was repeated every 24 h for three consecutive days. The 29 animals in the first group did not receive LED therapy. The 28 animals in the second group received LED light irradiation at 640 nm with 300 mW power, 46.8 J/cm2 energy density, 60 s irradiation time, and 0.385 cm2 spot size. The animals were irradiated at four points (46.8 J/cm2 per point) evenly distributed around the insertion site of the umbilical stump every 24 h for three consecutive days. Irradiation with LED light was applied before the umbilical stumps were immersed in the iodine solution. The time after birth at which the umbilical stump fell off of each calf was noted. The umbilical stumps of all animals fell off by the 25th day of age. After the umbilical stump fell off, the healing of the remnant wound was followed up to the 30th day after birth. The area of the wound was measured on the 15th, 20th, and 25th day after birth using digital photographs and computer-assisted area measurements. A two-tailed unpaired t test was applied to analyze the falling off the umbilical stump, whereas a Kruskal-Wallis one-way ANOVA test with a Dunn's multiple comparison test was used for the wound size evolution. GraphPad Prisma 5.0® and GraphPad StatMate 2.00® were used for the statistical analysis. The results revealed that phototherapy hastened the falling off the umbilical stump, accelerated navel healing, and reduced the mortality rate in newborn calves. Therefore, this study introduced a preventive and adjuvant after birth treatment that proved to be effective in reducing the incidences of omphalitis and newborn mortality.

Low intensity laser and LED therapies associated with lateral decubitus position and flexion exercises of the lower limbs in patients with lumbar disk herniation: clinical randomized trial.

UNLABELLED: The objective of this study is to evaluate the effectiveness of laser and LED therapies, associated with lateral decubitus position and flexion exercises of the lower limbs in patients with lumbar disk herniation (LDH). It is a randomized blinded clinical trial. Fifty-four subjects with LDH L4-L5 and L5-S1 were selected and randomly allocated into groups: laser 904 nm, placebo, and LED 945 nm. The numbers of subjects for each group that completed the treatment were 18, 13, and 18, respectively. Twelve points over the lumbar spine region (L2 to S1) and eight points on the injured thigh in the path of the lumbar roots L5 and S1 were irradiated. Irradiation parameters for each point were as follows: laser wavelength 904 ± 10 nm, average power 0.038 ± 20 % W, irradiated area 0.16 cm(2), energy per point 4 J, and treatment time per point 104 s; LED wavelength 945 ± 15 nm, power 0.1 W, irradiated area 1.0cm(2), energy per point 4 J, and treatment time per point 40 s. Lateral decubitus opposite to the side of the radicular was the standard position for all patients. After phototherapy and laser placebo sessions, the subjects performed sequences of flexion exercises of the lower limbs (ten per session) for 15 daily sessions. VARIABLES STUDIED: pain intensity assessed by visual analog scale (VAS), degree of flexion of the affected hip measured by the universal goniometer and functional capacity assessed by the Oswestry Disability Index. The three groups had statistically significant improvement in lumbar and radicular pain, in hip mobility, and in the functional disability index (p ≤ 0.001). There was a statistically significant difference (p = 0.024) in radicular pain between the groups, gait claudication and Oswestry Disability Index. We can conclude that in the treatment of L4-L5 and L5-S1 LDH with radiculopathy, LED, associated with lateral decubitus position and flexion exercises of the lower limbs, showed better therapeutic performance for radicular pain, gait claudication, and functional disability.

Effect of low-level laser therapy in an experimental model of osteoarthritis in rats evaluated through Raman spectroscopy.

OBJECTIVE: This work aimed to investigate the biochemical changes associated with low-level laser therapy (LLLT) using 660 and 780 nm, on a well-established experimental model of osteoarthritis (OA) in the knees of rats with induced collagenase, using histomorphometry and Raman spectroscopy. MATERIALS AND METHODS: Thirty-six Wistar rats were divided into four groups: control (GCON, n=9), collagenase without treatment (GCOL, n=9), collagenase with LLLT 660 nm treatment (G660, n=8), and collagenase with LLLT 780 nm treatment (G780, n=10). LLLT protocol was: 30 mW power output, 10 sec irradiation time, 0.04 cm(2) spot size, 0.3 J energy, 0.75 W/cm(2) irradiance, and 7.5 J/cm(2) fluence per session per day, during 14 days. Then, knees were withdrawn and submitted to histomorphometry and Raman spectroscopy analysis. Principal components analysis (PCA) and Mahalanobis distance were employed to characterize the spectral findings. RESULTS: Histomorphometry revealed a significant increase in the amount of collagen III for the group irradiated with 660 nm. The Raman bands at 1247, 1273, and 1453 cm(-1) (from principal component score PC2), attributed to collagen type II, and 1460 cm(-1) (from PC3), attributed to collagen type III, suggested that the LLLT causes acceleration in cellular activity, especially on the cells that repair cartilage, accelerating the breakdown of cartilage destroyed by collagenase and stimulating the fibroblast to synthesize repairing collagen III. CONCLUSIONS: LLLT accelerated the initial breakdown of cartilage destroyed by collagenase and stimulated the fibroblast to synthesize the repairing collagen III, suggesting a beneficial effect of LLLT on OA.

Low-level light-emitting diode therapy increases mRNA expressions of IL-10 and type I and III collagens on Achilles tendinitis in rats.

The present study investigated the effects of low-level light-emitting diode (LED) therapy (880 ± 10 nm) on interleukin (IL)-10 and type I and III collagen in an experimental model of Achilles tendinitis. Thirty male Wistar rats were separated into six groups (n = 5), three groups in the experimental period of 7 days, control group, tendinitis-induced group, and LED therapy group, and three groups in the experimental period of 14 days, tendinitis group, LED therapy group, and LED group with the therapy starting at the 7th day after tendinitis induction (LEDT delay). Tendinitis was induced in the right Achilles tendon using an intratendinous injection of 100 µL of collagenase. The LED parameters were: optical power of 22 mW, spot area size of 0.5 cm(2), and irradiation time of 170 s, corresponding to 7.5 J/cm(2) of energy density. The therapy was initiated 12 h after the tendinitis induction, with a 48-h interval between irradiations. The IL-10 and type I and III collagen mRNA expression were evaluated by real-time polymerase chain reaction at the 7th and 14th days after tendinitis induction. The results showed that LED irradiation increased IL-10 (p < 0.001) in treated group on 7-day experimental period and increased type I and III collagen mRNA expression in both treated groups of 7- and 14-day experimental periods (p < 0.05), except by type I collagen mRNA expression in LEDT delay group. LED (880 nm) was effective in increasing mRNA expression of IL-10 and type I and III collagen. Therefore, LED therapy may have potentially therapeutic effects on Achilles tendon injuries.

Low-level laser therapy combined with platelet-rich plasma on the healing calcaneal tendon: a histological study in a rat model.

The objective of this study was to investigate the effects of low-level laser therapy (LLLT) treatment alone (λ = 660 nm and λ = 830 nm) or associated with platelet-rich plasma (PRP). We used 54 male rats divided into six groups, with nine animals each: group 1, partial tenotomy; group 2 (GII), PRP; group 3 (GIII): λ660 nm; group 4 (GIV), λ830 nm; group 5 (GV), PRP + λ660 nm; and group 6 (GVI), PRP + λ830 nm. The protocol used was power density 0.35 W/cm(2), energy 0.2 J, energy density 7.0 J/cm(2), time 20 s per irradiated point, and number of points 3. Animals in groups GII, GV, and GVI received treatment with PRP, consisting of a single dose of 0.2 mL directly into the surgical site, on top of the tenotomy. Animals were killed on the 13th day post-tenotomy and their tendons were surgically removed for a quantitative analysis using polarization microscopy. The percentages of collagen fibers of types I and III were expressed as mean ± SD. Higher values of collagen fibers type I were obtained for groups GV and GVI when compared with all other groups (p < 0.05), whereas groups GIII and GIV showed no significant difference between them (p > 0.05). For collagen type III, a significant difference was observed between GII and all other groups (p < 0.5), but no significant difference was found between GIII and GIV and between GV and GVI. Results showed that the deposition of collagen type I was higher when treatment with PRP and LLLT was combined, suggesting a faster regeneration of the tendon.

Low-level laser therapy restores the oxidative stress balance in acute lung injury induced by gut ischemia and reperfusion.

It remains unknown if the oxidative stress can be regulated by low-level laser therapy (LLLT) in lung inflammation induced by intestinal reperfusion (i-I/R). A study was developed in which rats were irradiated (660 nm, 30 mW, 5.4 J) on the skin over the bronchus and euthanized 2 h after the initial of intestinal reperfusion. Lung edema and bronchoalveolar lavage fluid neutrophils were measured by the Evans blue extravasation and myeloperoxidase (MPO) activity respectively. Lung histology was used for analyzing the injury score. Reactive oxygen species (ROS) was measured by fluorescence. Both expression intercellular adhesion molecule 1 (ICAM-1) and peroxisome proliferator-activated receptor-y (PPARy) were measured by RT-PCR. The lung immunohistochemical localization of ICAM-1 was visualized as a brown stain. Both lung HSP70 and glutathione protein were evaluated by ELISA. LLLT reduced neatly the edema, neutrophils influx, MPO activity and ICAM-1 mRNA expression. LLLT also reduced the ROS formation and oppositely increased GSH concentration in lung from i-I/R groups. Both HSP70 and PPARy expression also were elevated after laser irradiation. Results indicate that laser effect in attenuating the acute lung inflammation is driven to restore the balance between the pro- and antioxidants mediators rising of PPARy expression and consequently the HSP70 production.

Comparative study of the topical application of Aloe vera gel, therapeutic ultrasound and phonophoresis on the tissue repair in collagenase-induced rat tendinitis.

The aim of our study was to compare topical use of Aloe vera gel, pulsed mode ultrasound (US) and Aloe vera phonophoresis on rat paw with collagenase-induced tendinitis. Edema size, tensile tendon strength, tendon elasticity, number of inflammatory cells and tissue histology were studied at 7 and 14 days after tendinitis induction. Pulse mode US parameters were: 1 MHz frequency, 100 Hz repetition rate, 10% duty cycle, and 0.5 W/cm(2) intensity, applied for 2 min each session. A 0.5 mL of Aloe vera gel at 2% concentration was applied for 2 min per session, topically and by phonophoresis. Topical application of Aloe vera gel did not show any statistically significant improvement in the inflammatory process, whereas phonophoresis enhanced the gel action reducing edema and number of inflammatory cells, promoting the rearrangement of collagen fibers and promoting also the recovery of the tensile strength and elasticity of the inflamed tendon to recover their normal pre-injury status. Results seem to indicate that Aloe vera phonophoresis is a promising technique for tendinitis treatment, without the adverse effect provoked by systemic anti-inflammatory drugs.

Anti-inflammatory effect of low-level laser and light-emitting diode in zymosan-induced arthritis.

OBJECTIVE: The aim of this work was to investigate the effect of low-level laser therapy (LLLT) and light-emitting diode (LED) on formation of edema, increase in vascular permeability, and articular joint hyperalgesia in zymosan-induced arthritis. BACKGROUND DATA: It has been suggested that low-level laser and LED irradiation can modulate inflammatory processes. MATERIAL AND METHODS: Arthritis was induced in male Wistar rats (250-280 g) by intra-articular injection of zymosan (1 mg in 50 microL of a sterile saline solution) into one rear knee joint. Animals were irradiated immediately, 1 h, and 2 h after zymosan administration with a semiconductor laser (685 nm and 830 nm) and an LED at 628 nm, with the same dose (2.5 J/cm(2)) for laser and LED. In the positive control group, animals were injected with the anti-inflammatory drug dexamethasone 1 h prior to the zymosan administration. Edema was measured by the wet/dry weight difference of the articular tissue, the increase in vascular permeability was assessed by the extravasation of Evans blue dye, and joint hyperalgesia was measured using the rat knee-joint articular incapacitation test. RESULTS: Irradiation with 685 nm and 830 nm laser wavelengths significantly inhibited edema formation, vascular permeability, and hyperalgesia. Laser irradiation, averaged over the two wavelengths, reduced the vascular permeability by 24%, edema formation by 23%, and articular incapacitation by 59%. Treatment with LED (628 nm), with the same fluence as the laser, had no effect in zymosan-induced arthritis. CONCLUSION: LLLT reduces inflammatory signs more effectively than LED irradiation with similar irradiation times (100 sec), average outputs (20 mW), and energy doses (2 J) in an animal model of zymosan-induced arthritis. The anti-inflammatory effects of LLLT appear to be a class effect, which is not wavelength specific in the red and infrared parts of the optical spectrum.

Effect of low-level laser therapy in the myonecrosis induced by Bothrops jararacussu snake venom.

OBJECTIVE: The aim of this work was to investigate the capacity of low-level laser therapy (LLLT) alone or in combination with antivenom (AV) to reduce myonecrosis induced by Bothrops jararacussu snake venom. BACKGROUND DATA: Myonecrosis is the most pronounced local effect caused by B. jararacussu venom. AV therapy and other first-aid treatments do not reverse these local effects. MATERIAL AND METHODS: Male Swiss mice were used. Myonecrosis was induced by injection of 0.6 mg/kg of B. jararacussu venom in the right gastrocnemius muscle and was evaluated at 3 or 24 h after venom injection. The site of venom administration was irradiated for 29 s with a low power semiconductor laser (685 nm) at a dose of 4.2 J/cm(2). Intravenous AV therapy (0.5 mL dose) was administered at different times: 30 min before venom injection or 0, 1, or 3 h afterward. Both AV therapy and LLLT treatments were duplicated in mice groups killed at 3 or 24 h. RESULTS: B. jararacussu venom caused a significant myonecrotic effect 3 and 24 h after venom injection. LLLT significantly reduced myonecrosis by 83.5% at 24 h (p < 0.05) but not at 3 h, and AV therapy alone was ineffective for reducing myonecrosis at 3 and 24 h. CONCLUSION: Only LLLT significantly reduced myonecrosis of the envenomed muscle, suggesting that LLLT is a potentially therapeutic approach for treating the local effects of B. jararacussu venom.

Effect of low-level laser therapy in the inflammatory response induced by Bothrops jararacussu snake venom.

This article reports the effect of low-level laser therapy (LLLT) on the edema formation and leukocyte influx caused by Bothrops jararacussu snake venom as an alternative treatment for Bothrops snakebites. The inflammatory reaction was induced by injection of 0.6 mg/kg of B. jararacussu venom, in gastrocnemius muscle. Cell influx and edema were evaluated at 3 or 24h after venom injection. Mice were irradiated at the site of injury by a low-level laser (685 nm) with a dose of 4.2J/cm(2). A therapy that combines LLLT and antivenom was also studied. B. jararacussu venom caused a significant edema formation 3 and 24h after its injection, and a prominent leukocyte infiltrate composed predominantly of neutrophils at 24h after venom inoculation. LLLT significantly reduced edema formation by 53% and 64% at 3 and 24h, respectively, and resulted in a reduction of neutrophils accumulation (P<0.05). The combined therapy showed to be more efficient than each therapy acting separately. In conclusion, LLLT significantly reduced the edema and leukocyte influx into the envenomed muscle, suggesting that LLLT should be considered as a potentially therapeutic approach for the treatment of the local effects of Bothrops species.

Cytokine mRNA expression is decreased in the subplantar muscle of rat paw subjected to carrageenan-induced inflammation after low-level laser therapy.

OBJECTIVE: The objective of this work was to investigate the anti-inflammatory effects of low-level laser therapy, applied at different wavelengths (660 and 684 nm), on cytokine mRNA expression after carrageenan-induced acute inflammation in rat paw. BACKGROUND DATA: Low-level laser therapy (LLLT) has been observed to reduce pain in inflammatory disorders. However, little is known about the mechanisms behind this effect or whether it is wavelength-specific. MATERIALS AND METHODS: The test sample consisted of 32 rats divided into four groups: A(1) (control-saline), A(2) (carrageenan-only), A(3) (carrageenan + 660 nm laser therapy), and A(4) (carrageenan + 684 nm laser therapy). The animals from groups A(3) and A(4) were irradiated 1 h after induction of inflammation by carrageenan injection. Continuous-wave red lasers with wavelengths of 660 and 684 nm and dose of 7.5 J/cm(2) were used. RESULTS: Both the 660 nm and 684 nm laser groups had 30%-40% lower mRNA expression for cytokines TNF-alpha, IL-1beta, and IL-6 in the paw muscle tissue than the carrageenan-only control group. Cytokine measurements were made 3 h after laser irradiation of the paw muscle, and all cytokine differences between the carrageenan-only control group and the LLLT groups were statistically significant (p < 0.001). CONCLUSIONS: LLLT at the 660-nm and 684-nm wavelengths administered to inflamed rat paw tissue at a dose of 7.5 J/cm(2) reduce cytokine mRNA expression levels within 3 h in the laser-irradiated tissue.

Comparison between wound healing in induced diabetic and nondiabetic rats after low-level laser therapy.

OBJECTIVE: The aim of this work was to compare the effect of low-level laser therapy (LLLT) on the wound healing process in nondiabetic and diabetic rats. BACKGROUND DATA: Among the clinical symptoms caused by diabetes mellitus, a delay in wound healing is a potential risk for patients. It is suggested that LLLT can improve wound healing. METHODS: The tissue used for this study was extracted from animals suffering from diabetes, which was induced by Streptozotocin, and from nondiabetic rats. Animals were assembled into two groups of 25 rats each (treated and control) and further subdivided into two groups: diabetic (n = 15) and nondiabetic (n = 10). A full-thickness skin wound was made on the dorsum area, with a round 8-mm holepunch. The treated group was irradiated by a HeNe laser at 632.8 nm, with the following parameters: 15 mW, exposition time of 17 sec, 0.025 cm2 irradiated area, and energy density of 10 J/cm2. Square full-thickness skin samples (18 mm each side, including both injured and noninjured tissues) were obtained at 4, 7, and 15 days after surgery and analyzed by qualitative and quantitative histological methods. RESULTS: Quantitative histopathological analysis confirmed the results of the qualitative analysis through histological microscope slides. When comparing tissue components (inflammatory cells, vessels and fibroblast/area), we found that treated animals had a less intense inflammatory process than controls. CONCLUSION: Results obtained by both qualitative and quantitative analyses suggested that irradiation of rats with HeNe (632.8 nm), at the tested dose, promoted efficient wound healing in both nondiabetic and diabetic rats as, compared to the control group.

Dentin evaluation after Nd:YAG laser irradiation using short and long pulses.

OBJECTIVE: Several reports have demonstrated the advantages of using the Nd:YAG laser to reduce dentin permeability by melting the dentin surface. A comparative study using different pulse durations can be useful to obtain further information about the laser-hard tissue interaction. MATERIALS AND METHODS: The present study pursues the evaluation of the morphological and chemical changes in human dentin surface resulting from Nd:YAG laser (lambda = 1064 nm) irradiation, with a total energy of 0.9 J distributed in 1, 2, 3, and 6 pulses with different pulse durations to promote surface melting and dentinal tubule occlusion. After irradiation, the samples were submitted to scanning electron microscopy (SEM) analysis for morphological study and energy-dispersive spectrometry (EDS) analysis for evaluation of the concentration of calcium and phosphorous in the melted layer. RESULTS: SEM analysis of the irradiated dentin surface showed surface structural changes due to laser irradiation, where the morphological changes are dependent on the laser pulse duration. EDS analysis showed an increase of calcium and phosphorous concentrations after Nd:YAG laser exposure, but no correlation with the number of pulses or pulse duration was found. CONCLUSION: Our results suggest that longer interaction times resulted in more evident effects with more melted substrate than shorter pulses, and in both cases the resultant melted layer contains a greater concentration of inorganic substances than non-irradiated dentin.