Effect of the transdermal low-level laser therapy on endothelial function

The effect of low-level laser therapy (LLLT) on the cardiovascular system is not fully established. Since the endothelium is an important endocrine element, establishing the mechanisms of LLLT action is an important issue.The aim of the study was to evaluate the effect of transdermal LLLT on endothelial function.In this study, healthy volunteers (n?=?40, age?=?20–40 years) were enrolled. N?=?30 (14 female, 16 male, mean age 30?±?5 years) constituted the laser-irradiated group (LG). The remaining 10 subjects (6 women, 4 men, mean age 28?±?5 years) constituted the control group (CG). Participants were subjected to LLLT once a day for three consecutive days. Blood for biochemical assessments was drawn before the first irradiation and 24 h after the last session. In the LG, transdermal illumination of radial artery was conducted (a semiconductor laser λ?=?808 nm, irradiation 50 mW, energy density 1.6 W/cm² and a dose 20 J/day, a total dose of 60 J). Biochemical parameters (reflecting angiogenesis: vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), angiostatin; antioxidative status: glutathione (GSH) and the nitric oxide metabolic pathway: symmetric dimethylarginine (SDMA), asymmetric dimethylarginine (ADMA) and l-arginine) were assessed. In the LG, a significant increase in GSH levels and considerable decrease in angiostatin concentration following the LLLT were observed. No significant differences in levels of the VEGF, FGF, SDMA, ADMA were observed.LLLT modifies vascular endothelial function by increasing its antioxidant and angiogenic potential. We found no significant differences in levels of the nitric oxide pathway metabolites within 24 h following the LLLT irradiation.     

Zymographic and ultrastructural evaluations after low-level laser irradiation on masseter muscle of HRS/J strain mice

Low-level laser therapy (LLLT) has been widely used in the treatment of the stomatognathic system dysfunction; however, its biological effect remains poorly understood. This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm², 40 mW) on masseter muscle of HRS/J mice after different numbers of laser irradiations (three, six, and ten) for 20 s in alternate days. Three experimental groups were defined according to the number of laser irradiations and three control groups (n?=?5) were used. On the third day after the last irradiation, all animals were killed and the masseter muscle was removed and processed for the following analysis: (a) transmission electron microscopy, (b) zymography, (c) immunohistochemistry for vascular endothelial growth factor (VEGF) and VEGFR-2. The results showed: (a) with six laser applications, a dilation of T tubules, and sarcoplasmic reticulum cistern, increased pinocytosed vesicles in the endothelium; with ten laser applications, few pinocytic vesicles in the endothelium and condensed mitochondria. (b) Under the conditions of this study, the synthesis of other matrix metalloproteinases was not observed, only the MMP-2 and -9. (c) After ten laser irradiations, immunostaining was observed only for VEGFR-2. We conclude that after six laser applications, ultrastructural changes may facilitate the Ca⁺² transfer to cytosol and increase the fluid transport from one surface to another. The ultrastructural changes and no immunostaining for VEGF with ten applications may decrease the metabolic activity as well as damage the angiogenic process, suggesting that an effective number of laser applications may be less than ten, associating to this therapy a better cost–benefit.     

Effect of low-level laser therapy after rapid maxillary expansion: a clinical investigation

To evaluate the effectiveness low-level laser therapy (LLLT) on the repair of the mid palatal suture, after rapid maxillary expansion (RME). A single-operator, randomized single-blind placebo-controlled study was performed at the Orthodontic Department at the Dental Hospital of Bellvitge. Barcelona University, Hospitalet de Llobregat, Spain. Thirty-nine children (range 6–12 years old), completed RME and were randomized to receive active LLLT (n?=?20) or placebo (n?=?19). The laser parameters and dose were 660 nm, 100 mW, CW, InGaAlP laser, illuminated area 0.26 cm², 332 mW/cm², 60 s to four points along midpalatal suture, and 30 s to a point each side of the suture. A total of seven applications were made on days 1, 7, 14, 28, 42, 56, and 70 of the retention phase RME. A cone beam computed tomography (CBCT) scan was carried out on the day of the first laser treatment, and at day 75, a second CBCT scan was performed. Two radiologists synchronized the slices of two scans to be assessed. P?=?0.05 was considered to be statistically significant. At day 75 of the suture, the irradiated patients presented a greater percentage of approximate zones in the anterior (p?=?0.008) and posterior (p?=?0.001) superior suture—and less approximation in the posterior superior suture (p?=?0.040)—than the placebo group. LLLT appears to stimulate the repair process during retention phase after RME.     

Effects of different fluences of low-level laser therapy in an experimental model of spinal cord injury in rats

The aim of this study was to evaluate the in vivo response of different fluences of low-level laser therapy (LLLT) on the area of the injury, inflammatory markers, and functional recovery using an experimental model of traumatic spinal cord injury (SCI). Thirty two rats were randomly divided into four experimental groups: control group (CG), laser-treated group 500 J/cm² (L-500), laser-treated group 750 J/cm² (L-750), and laser-treated group 1000 J/cm² (L-1000). SCI was performed by an impactor equipment (between the ninth and tenth thoracic vertebrae), with a pressure of 150 kdyn. Afterwards, the injured region was irradiated daily for seven consecutive sessions, using an 808-nm laser, at the respective fluence of each experimental groups. Motor function and tactile sensitivity were performed on days 1 and 7 post-surgery. Animals were euthanized on the eighth day after injury, and the samples were retrieved for histological and immunohistochemistry analyses. Functional evaluation and tactile sensitivity were improved after LLLT, at the higher fluence. Additionally, LLLT, at 750 and 1000 J/cm², reduces the lesion volume and modulates the inflammatory process with decrease of CD-68 protein expression. These results suggest that LLLT at higher doses was effective in promoting functional recovery and modulating inflammatory process in the spinal cord of rats after SCI.     

The influence of low-level laser therapy on parameters of oxidative stress and DNA damage on muscle and plasma in rats with heart failure

In heart failure (HF), there is an imbalance between the production of reactive oxygen species and the synthesis of antioxidant enzymes, causing damage to the cardiovascular function and increased susceptibility to DNA damage. The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) on parameters of oxidative stress and DNA damage in skeletal muscle and plasma of rats with HF. Wistar rats were allocated into six groups: “placebo” HF rats (P-HF, n?=?9), “placebo” Sham rats (P-sham, n?=?8), HF rats at a dose 3 J/cm² of LLLT (3 J/cm²-HF, n?=?8), sham rats at a dose 3 J/cm² of LLLT (3 J/cm²-sham, n?=?8), HF rats at a dose 21 J/cm² of LLLT (21 J/cm²-HF, n?=?8) and sham rats at a dose 21 J/cm² of LLLT (21 J/cm²-sham, n?=?8). Animals were submitted to a LLLT protocol for 10 days at the right gastrocnemius muscle. Comparison between groups showed a significant reduction in superoxide dismutase (SOD) activity in the 3 J/cm²-HF group (p?=?0.03) and the 21 J/cm²-HF group (p?=?0.01) compared to the P-HF group. 2′,7′-Dihydrodichlorofluorescein (DCFH) oxidation levels showed a decrease when comparing 3 J/cm²-sham to P-sham (p?=?0.02). The DNA damage index had a significant increase either in 21 J/cm²-HF or 21 J/cm²-sham in comparison to P-HF (p?=?0.004) and P-sham (p?=?0.001) and to 3 J/cm²-HF (p?=?0.007) and 3 J/cm²-sham (p?=?0.037), respectively. Based on this, laser therapy appears to reduce SOD activity and DCFH oxidation levels, changing the oxidative balance in the skeletal muscle of HF rats. Otherwise, high doses of LLLT seem to increase DNA damage.     

Low-level laser therapy enhances the expression of osteogenic factors during bone repair in rats

The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) on bone formation, immunoexpression of osteogenic factors, and biomechanical properties in a tibial bone defect model in rats. Sixty male Wistar rats were distributed into bone defect control group (CG) and laser irradiated group (LG). Animals were euthanized on days?15, 30, and 45 post-injury. The histological and morphometric analysis showed that the treated animals presented no inflammatory infiltrate and a better tissue organization at 15 and 30 days postsurgery. Also, a higher amount of newly formed bone was observed at 15 days postsurgery. No statistically significant difference was observed in cyclooxygenase-2 immunoexpression among the groups at 15, 30, and 45 days in the immunohistochemical analysis. Considering RUNX-2, the immunoexpression was statistically higher in the LG compared to the CG at 45 days. BMP-9 immunoexpression was significantly higher in the LG in comparison to CG at day?30. However, there was no expressivity for this immunomarker, both in the CG and LG, at the day?45 postsurgery. No statistically significant difference was observed in the receptor activator of nuclear factor kappa-B ligand immunoexpression among the groups in all periods evaluated. No statistically significant difference among the groups was observed in the maximal load in any period of time. Our findings indicate that laser therapy improved bone healing by accelerating the development of newly formed bone and activating the osteogenic factors on tibial defects, but the biomechanical properties in LG were not improved.     

High doses of laser phototherapy can increase proliferation in melanoma stromal connective tissue

It is well established that laser phototherapy (LP) is contraindicated directly over cancer cells, due to its bio modulatory effects in cell and blood vessel proliferation. The aim of the present study was to analyze the influence of typical low-level laser therapy (LLLT) and high intensity laser therapy (HILT) and an in-between dose of 9 J on collagen fibers and blood vessels content in melanoma tumors (B16F10) implanted in mice. Melanoma tumor cells were injected in male Balb C mice which were distributed in four groups: control (no irradiated) or irradiated by 3, 9, or 21 J (150; 450, or 1050 J/cm²). LP was performed in daily sessions for 3 days with a InGaAlP—660 nm (mean output: 50 mW, spot size: 2 mm²). Tumor volume was analyzed using (1) picrosirius staining to quantify collagen fibers content and (2) Verhoeff’s method to quantify blood vessels content. Tumor growth outcome measured in the 3-J group was not significantly different from controls. Nine and 21-J groups, presented significant and dose-dependent increases in tumor volume. Quantitative analysis of the intensity of collagen fibers and their organization in stroma and peri-tumoral microenvironment showed significant differences between irradiated and control group. Blood vessels count of 21-J group outnumbered the other groups. High doses (≥ 9 J) of LP showed a dose-dependent tumor growth, different collagen fibers characteristics, and eventually blood vessel growth, while a typical LLLT dose (3 J) appeared harmless on melanoma cell activity.     

Effect of low-level laser therapy on types I and III collagen and inflammatory cells in rats with induced third-degree burns

Low-level laser therapy (LLLT) has been increasingly used to accelerate wound healing in third-degree burns. This study investigated the effects of lasers on the tissue repair process of third-degree burns. Burns were produced on the backs of male Wistar rats. The animals were divided into four groups (n?=?12): control, injury, LLLT 3 J/cm², and LLLT 4 J/cm². Each group was further divided into two subgroups; the rats in one subgroup were killed on day 8 and those in the other, on day 16 after injury. The animals in LLLT 3 J/cm² and LLLT 4 J/cm² were irradiated 1 h after injury, and irradiation was repeated every 48 h. Laser (660 nm, 35 mW) treatment at fluences of 3 and 4 J/cm² were used. After killing the rats, tissue fragments from the burnt area were removed for histological analysis. The LLLT-treated groups showed a significant decrease (p <0.05) in the number of inflammatory cells and increased collagen deposition compared to the injury group. Laser irradiation (both 3 and 4 J/cm²) resulted in reduction in the inflammatory process and improved collagen deposition, thereby ameliorating the healing of third-degree burns.     

Effects of oral motor exercises and laser therapy on chronic temporomandibular disorders: a randomized study with follow-up

This study investigated the efficacy of combining low-level laser therapy (LLLT) with oral motor exercises (OM-exercises) for rehabilitation of patients with chronic temporomandibular disorders (TMDs). Eighty-two patients with chronic TMD and 20 healthy subjects (control group) participated in the study. Patients were randomly assigned to treatment groups: GI (LLLT?+?OM exercises), GII (orofacial myofunctional therapy—OMT—which contains pain relief strategies and OM-exercises), and GIII (LLLT placebo?+?OM-exercises) and GIV (LLLT). LLLT (AsGaAl; 780-nm wavelength; average power of 60 mW, 40 s, and 60?±?1.0 J/cm²) was used to promote analgesia, while OM-exercises were used to reestablish the orofacial functions. Evaluations at baseline (T1), after treatment immediate (T2), and at follow-up (T3) were muscle and joint tenderness to palpation, TMD severity, and orofacial myofunctional status. There was a significant improvement in outcome measures in all treated groups with stability at follow-up (Friedman test, P?<?0.05), but GIV did not show difference in orofacial functions after LLLT (P?>?0.05). Intergroup comparisons showed that all treated groups had no difference in tenderness to palpation of temporal muscle compared to GC at follow-up (Kruskal-Wallis test, P?<?0.01). Moreover, GI, GII, and GIII showed no difference from GC in orofacial functional condition (T2 and T3) while they differed significantly from GIV (P?<?0.01). In conclusion, LLLT combined with OM-exercises was more effective in promoting TMD rehabilitation than LLLT alone was. Similar treatment results were verified with the OMT protocol.     

Effect of low-level laser therapy on angiogenesis and matrix metalloproteinase-2 immunoexpression in wound repair

Low-level laser therapy (LLLT) induces anti-inflammatory and angiogenic activities in wound healing. However, the mechanism of action and optimal parameters require further clarification. In this study, we investigated the effects of LLLT on wound healing matrix metalloproteinase (MMP)-2 immunoexpression and angiogenic processes. Twenty female Wistar rats were randomly divided into four groups (n?=?5) according to the treatments as follows. CG7 and CG14 were control groups at days 7 and 14, respectively, which received physiological saline (0.9 % NaCl daily). LG7 and LG14 were laser therapy groups at days 7 and 14, respectively, which received two (LG7) or four (LG14) LLLT applications (40 mW; 660 nm; 4 J/cm²). A dorsal skin sample in the wound area (measuring 2 cm²) was removed after the experimental period, and then the animals were euthanized. The specimens were processed for qualitative and quantitative histological analyses and measurement of MMP-2 expression in the dermis and epidermis. A persistent crust and moderate number of inflammatory cells were found in CG7 and CG14 groups. In the LG14 group, wounds demonstrated complete re-epithelization at the remodeling phase. Angiogenesis and MMP-2 expression were higher in LLLT-treated groups, particularly the LG14 group, which correlated according to the Spearman correlation test. LLLT improves wound healing by enhancing neocollagenesis, increasing the amount of new vessels formed in the tissue (neoangiogenesis), and modulating MMP-2 expression. Epidermal overexpression of MMP-2 was correlated to angiogenic processes.     

Low-level laser therapy improves the inflammatory profile of rats with heart failure

Following heart failure (HF), immune activation leads to an imbalance between pro-inflammatory and anti-inflammatory cytokines. Low-level laser therapy (LLLT) has been used as an anti-inflammatory treatment in several disease conditions. However, the effect of LLLT on the skeletal muscle of rats with HF remains unclear. The present report aimed to evaluate the influence of LLLT on the inflammatory profile of rats with HF. The left coronary artery was ligated to induce HF and a sham operation was performed in the control groups. Male Wistar rats (n?=?49) were assigned to one of six groups: placebo sham rats (P-Sham; n?=?8), LLLT at a dose of 3 J/cm² sham rats (3 J/cm²-Sham; n?=?8), LLLT at a dose of 21 J/cm² sham rats (21 J/cm²-Sham; n?=?8), placebo HF rats (P-HF; n?=?9), LLLT at a dose of 3 J/cm² HF rats (3 J/cm²-HF; n?=?8), and LLLT at a dose of 21 J/cm² HF rats (21 J/cm²-HF; n?=?8). Four weeks after myocardial infarction or sham surgery, rats were subjected to LLLT (InGaAlP 660 nm, spot size 0.035 cm², output power 20 mW, power density 0.571 W/cm², energy density 3 or 21 J/cm², exposure time 5.25 s and 36.75 s) on the right gastrocnemius for 10 consecutive days. LLLT reduced plasma IL-6 levels (61.3 %; P?<?0.01), TNF-α/IL-10 (61.0 %; P?<?0.01) and IL-6/IL-10 ratios (77.3 %; P?<?0.001) and increased IL-10 levels (103 %; P?<?0.05) in the 21 J/cm²-HF group. Moreover, LLLT reduced the TNF-α (20.1 % and 21.3 %; both P?<?0.05) and IL-6 levels (54.3 % and 37.8 %; P?<?0.01 and P?<?0.05, respectively) and the IL-6/IL-10 ratio (59.7 % and 42.2 %; P?<?0.001 and P?<?0.05, respectively) and increased IL-10 levels (81.0 % and 85.1 %; both P?<?0.05) and the IL-10/TNF-α ratio (171.5 % and 119.8 %; P?<?0.001 and P?<?0.05, respectively) in the gastrocnemius in the 3 J/cm²-HF and 21 J/cm²-HF groups. LLLT showed systemic and skeletal muscle anti-inflammatory effects in rats with HF.     

Low-level laser therapy prevents degenerative morphological changes in an experimental model of anterior cruciate ligament transection in rats

The aim of this study was to analyze the effects of low-level laser therapy (LLLT) on the prevention of cartilage damage after the anterior cruciate ligament transection (ACLT) in knees of rats. Thirty male rats (Wistar) were distributed into three groups (n?=?10 each): injured control group (CG); injured laser-treated group at 10 J/cm² (L10), and injured laser-treated group at 50 J/cm² (L50). Laser treatment started immediately after the surgery and it was performed for 15 sessions. An 808 nm laser, at 10 and 50 J/cm², was used. To evaluate the effects of LLLT, the qualitative and semi-quantitative histological, morphometric, and immunohistochemistry analysis were performed. Initial signs of tissue degradation were observed in CG. Interestingly, laser-treated animals presented a better tissue organization, especially at the fluence of 10 J/cm². Furthermore, laser phototherapy was able of modulating some of the aspects related to the degenerative process, such as the prevention of proteoglycans loss and the increase in cartilage area. However, LLLT was not able of modulating chondrocytes proliferation and the immunoexpression of markers related to inflammatory process (IL-1 and MMP-13). This study showed that 808 nm laser, at both fluences, prevented features related to the articular degenerative process in the knees of rats after ACLT.     

LLLT actives MMP-2 and increases muscle mechanical resistance after nerve sciatic rat regeneration

The purpose of this study was to analyze the low-level laser therapy (LLLT) on metalloproteinase expression and the mechanical strength of skeletal muscle regeneration after peripheral nerve injury. Rats were subjected to crush injury of the right sciatic nerve, followed by LLLT (830 nm, 35, 70, 140, and 280 J/cm²) for 21 consecutive days. Functional gait analysis was performed at weekly intervals and the animals were sacrificed after the last evaluation at day 21 for collection of the gastrocnemius muscles, which were submitted to analysis of resistance, and the tibialis anterior, for evaluation of metalloproteinase-2 (MMP-2). The results were statistically analyzed at a significance level of 5%. The irradiated groups showed a significant decrease in the sciatic functional index and a significant increase in the mechanical strength when compared to the injured group with no treatment (p?<?0.05), with no significant difference among the energy densities used. While no difference among groups was observed for the activity of MMP-2 in pro-active band, at the intermediate band, the activity was significantly higher (p?<?0.05) for the groups irradiated with 35, 70, and 140 J/cm², and at the active band, the activity was significantly more intense in the group irradiated with 280 J/cm². The present study demonstrated that injury of the sciatic nerve, with consequent muscle denervation, are benefited by the laser therapy, which restores neuromuscular function, active MMP-2 and increases the maximum breaking strength.     

Infrared low-level diode laser on serum chemokine MCP-1 modulation in mice

The effect of the low-level laser therapy (LLLT) in the modulation of cells related to inflammatory processes has been widely studied, with different parameters. The objective was to investigate the immediate and cumulative effect of infrared LLLT on chemokine monocyte chemotactic protein-1 (MCP-1) modulation in mice. Fifty-two isogenic mice were distributed in seven groups: control (n?=?10, no surgical procedure), laser I (n?=?7, surgical procedure and a single LLLT exposure 12 h after the surgery), laser II (n?=?7, surgery followed by two LLLT exposures, 12 and 36 h after surgery), and laser III (n?=?7, surgery followed by three LLLT exposures, 12, 36, and 60 h after surgery). For each group, a sham group (n?=?21) underwent surgery without laser application. The animals in the laser groups received an infrared diode continuous laser exposure (AsGaAl, 780 nm wavelength, power of 20 mW, energy density of 10 J/cm², spot size of 0,04 cm²) on three points (20 s per point), and a final energy of 0.4 J. The animals were sacrificed 36 h (laser I and sham I groups), 60 h (laser II and sham II), and 84 h (laser III and sham III groups) after surgery. The MCP-1 concentrations were measured by cytometric bead array. There was no significant difference between the three periods in the sham group (p?=?0.3). There was a lower concentration of MCP-1 in the laser III group compared to the laser I group (p?=?0.05). The infrared LLLT showed a cumulative effect in the modulation of chemokine MCP-1 concentration. Three LLLT exposures were necessary to achieve the MCP-1 modulation.     

Effect of low-level laser therapy in patients with chronic knee osteoarthritis: a single-blinded randomized clinical study

The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on pain relief and functional performance in patients with chronic knee osteoarthritis (OA). Forty patients with knee OA were randomly assigned into active laser group (n?=?20) and placebo laser group (n?=?20). The LLLT device used was a Ga–As diode laser with a power output of 50 mW, a wavelength of 850 nm, and a diameter beam of 1 mm. Eight points were irradiated and received dosage of 6 J/point for 60 s, with a total dosage of 48 J/cm² in each session. The placebo group was identical but treated without emission of energy. LLLT was applied two times per week over the period of 4 weeks. Outcome measurements included pain intensity at rest and at movement on visual analog scale, knee function using Western Ontario McMaster Universities Osteoarthritis Index scale, and ambulation duration. These measurements were collected at baseline and post-intervention. The results showed significant improvements in all assessment parameters in both groups compared to baseline. Active laser group showed significant differences in pain intensity at rest and movement, knee function, and ambulation duration when compared with the placebo group. Therefore, LLLT seemed to be an effective modality for short-term pain relief and function improvement in patients with chronic knee OA.     

Assessment of Functional Recovery of Sciatic Nerve in Rats Submitted to Low-Level Laser Therapy with Different Fluences. An Experimental Study

Peripheral nerve lesions caused sensory and motor deficits along the distribution of the injured nerve. Numerous researches have been carried out to enhance and/or accelerate the recovery of such lesions. The objective of this study was to assess the functional recovery of sciatic nerve in rats subjected to different fluences of low-level laser therapy (LLLT). Thirty-six animals were randomly divided into four groups: one consisting of sham rats and three others irradiated with progressive fluencies of 10 J/cm², 40 J/cm² and 80 J/cm² of laser AsGaAl (830 nm) for 21 consecutive days. They were evaluated by the Sciatic Functional Index (SFI) method. The crush injury was performed by using a portable device with dead weight of 5,000 g whose load was applied for 10 min. A digital camera was used to record the footprints left on the acrylic track, before surgery and after, on the 7th, 14th, and 21st days. The results also showed that on the 7th day, there was a difference between the groups irradiated with 40 J/cm², when compared with the sham group (p < 0.05). On the 14th day the groups irradiated with 40 J/cm² and 80 J/cm² also presented better results when compared with sham, however, on the 21st day, no inter-group difference was found (p > 0.05). It was possible to observe that the LLLT at fluency of 40 J/cm² and 80 J/cm² had a positive influence on the acceleration of the functional nerve recovery.     

Effects of low-level laser therapy and epidermal growth factor on the activities of gingival fibroblasts obtained from young or elderly individuals

This study evaluated the effects of low-level laser therapy (LLLT) and epidermal growth factor (EGF) on fibroblasts obtained from young and elderly individuals. Gingival fibroblasts from young (Y) and elderly (E) individuals were seeded in wells of 24-well plates with Dulbecco’s modified Eagle’s medium (DMEM) containing 10 % of fetal bovine serum (FBS). After 24 h, the cells were irradiated (LASERTable—InGaAsP—780?±?3 nm, 25 mW, 3 J/cm²) or exposed to EGF (100 μM). After 72 h, cells were evaluated for viability, migration, collagen and vascular endothelial growth factor (VEGF) synthesis, and gene expression of growth factors. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α?=?5 %). Y and E fibroblasts irradiated with laser or exposed to EGF showed increased viability and collagen synthesis. Enhanced cell migration was observed for Y fibroblasts after both treatments, whereas only the LLLT stimulated migration of E cells. VEGF synthesis was higher for Y and E cells exposed to EGF, while this synthesis was reduced when E fibroblasts were irradiated. Increased gene expression of VEGF was observed only for Y and E fibroblasts treated with LLLT. Regardless of a patient’s age, the LLLT and EGF applications can biostimulate gingival fibroblast functions involved in tissue repair.     

Effect of low-level laser therapy on healing of tenotomized Achilles tendon in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is associated with musculoskeletal damage. Investigations have indicated that healing of the surgically tenotomized Achilles tendon was considerably augmented following low-level laser therapy (LLLT) in non-diabetic, healthy animals. The aim of the present study was to evaluate the effect of LLLT on the Achilles tendon healing in streptozotocin-induced diabetic (STZ-D) rats via a biomechanical evaluating method. Thirty-three rats were divided into non-diabetic (n?=?18) and diabetic (n?=?15) groups. DM was induced in the rats by injections of STZ. The right Achilles tendons of all rats were tenotomized 1 month after STZ injections. The two experimental groups (n?=?6 for each group) of non-diabetic rats were irradiated with a helium–neon (He–Ne) laser at 2.9 and 11.5 J/cm² for ten consecutive days. The two experimental groups of diabetic rats (n?=?5 for each group) were irradiated with a He–Ne laser at 2.9 and 4.3 J/cm² for ten consecutive days. The tendons were submitted to a tensiometric test. Significant improvements in the maximum stress (MS) values (Newton per square millimeter) were found following LLLT at 2.9 J/cm² in both the non-diabetic (p?=?0.031) and diabetic (p?=?0.019) experimental groups when compared with their control groups. LLLT at 2.9 J/cm² to the tenotomized Achilles tendons in the non-diabetic and diabetic rats significantly increased the strength and MS of repairing Achilles tendons in our study.     

Analysis of the variation in low-level laser energy density on the crushed sciatic nerves of rats: a morphological,quantitative, and morphometric study

The objective of this study was to evaluate three energy densities of low-level laser therapy (LLLT, GaAlAs, 780 nm, 40 mW, 0.04 cm²) for the treatment of lesions to peripheral nerves using the sciatic nerve of rats injured via crushing model (15 kgf, 5.2 MPa). Thirty Wistar rats (♂, 200–250 g) were divided into five groups (n?=?6): C—control, not injured, and irradiated; L0—injured nerve without irradiation; L4—injured nerve irradiated with LLLT 4 J/cm² (0.16 J); L10—injured nerve irradiated with LLLT 10 J/cm² (0.4 J); and L50—injured nerve irradiated with LLLT 50 J/cm² (2 J). The animals were sacrificed 2 weeks after the injury via perfusion with glutaraldehyde (2.5%, 0.1 M sodium cacodylate buffer). The nerve tissue was embedded in historesin, cut (3 μm), mounted on slides, and stained (Sudan black and neutral red). The morphological and quantitative analysis (myelin and blood capillary densities) and morphometric parameters (maximum and minimum diameters of nerve fibers, axon diameter, G-ratio, myelin sheath thickness) were assessed using the ImageJ software. ANOVA (parametric) or Kruskal-Wallis (nonparametric) tests were used for the statistical analysis. Groups L0, L4, L10, and L50 exhibited diminished values of all the quantitative and morphometric parameters in comparison to the control group. The morphological, quantitative, and morphometric data revealed improvement after injury in groups L4, L10, and L50 (irradiated groups) compared to the injured-only group (L0); the best results, in general, were observed for the L10 group after 15 days of nerve injury.