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/cm², energy 0.2 J, energy density 7.0 J/cm², 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.     

The effect of low-level laser therapy on non-surgical periodontal treatment: a randomized controlled,single-blind,split-mouth clinical trial

The purpose of this split-mouth, single-blind, controlled clinical study was to evaluate the impact of low-level laser therapy (LLLT) as an adjunct to non-surgical treatment of chronic periodontitis. Twenty-five systemically healthy and non-smoking adults with chronic periodontitis who had at least two bilateral premolar teeth with probing pocket depth (PPD) of 7?≥?x?≥?5 mm were included in the study. In the periodontal examination of these patients, PPD, gingival index (GI), plaque index (PI), clinical attachment level (CAL), and bleeding on probing (BOP) were recorded at the baseline, first, third, and sixth months after treatment. Gingival crevicular fluid (GCF) samples were taken at the baseline, first week, and first month after treatment. The collected GCF samples were analyzed using the MAGPIX? system with a Bio-Plex Pro? Human Cytokine 27-plex kit. After non-surgical periodontal treatment, LLLT with an energy density of 7.64 J/cm² was performed four times: immediately after scaling and root planning (SRP) and on the first, third, and seventh day after treatment. In the first month, PPD levels were significantly (p?<?0.05) lower in the SRP?+?LLLT group than in the SRP group. At the third and sixth months, CAL, PPD, and GI were significantly (p?<?0.05) lower in the SRP?+?LLLT group than in the SRP group. Differences in GCF cytokines levels among the group were not statistically significant. Within the limitations of this study, it is indicated that LLLT as an adjunct to non-surgical periodontal treatment has a positive impact on clinical parameters.     

Pulsed LLLT improves tendon healing in rats: a biochemical,organizational, and functional evaluation

In the last decades, the tendon injuries have increased substantially. Previous results suggested that low-level laser treatment (LLLT) promotes synthesis of extracellular matrix and improves the functional properties of the tendon. The aim of this study was to evaluate the effects of different protocols of LLLT on partially tenotomized tendons. Adult male rats were divided into the following: G1—intact, G2—injured, G3—injured?+?LLLT (4 J/cm² continuous), G4—injured?+?LLLT (4 J/cm² at 20 Hz). G2, G3, and G4 were euthanized 8 days after injury. G5—injured, G6—injured?+?LLLT (4 J/cm² continuous), and G7—injured?+?LLL (4 J/cm² at 20 Hz until the seventh day and 2 kHz from 8 to 14 days). G5, G6, and G7 were euthanized on the 15th day. Glycosaminoglycan (GAG) level was quantified by dimethylmethylene blue method and analyzed on agarose gel. Toluidine blue (TB) stain was used to observe metachromasy. CatWalk system was used to evaluate gait recovery. Collagen organization was analyzed by polarization microscopy. The GAG level increased in all transected groups, except G5. In G6 and G7, there was a significant increase in GAG in relation to G5. In G3 and G4, the presence of dermatan sulfate band was more prominent than G2. TB stains showed intense metachromasy in the treated groups. Birefringence analysis showed improvement in collagen organization in G7. The gait was significantly improved in G7. In conclusion, pulsed LLLT leads to increased organization of collagen bundles and improved gait recovery.     

The efficacy of platelet-rich plasma gel in MRSA-related surgical wound infection treatment: an experimental study in an animal model

Introduction

The wound healing properties of platelet-rich plasma (PRP) gel have been documented in many studies. PRP gel has also become a promising agent for treating surgical site infections. In this study, we investigated the antibacterial activity and wound healing effectiveness of PRP in an animal model of Methicillin-resistant Staphylococcus aureus subsp. aureus (MRSA N315)-contaminated superficial soft tissue wounds.

Materials and methods

Subcutaneous wounds in Wistar Albino male rats were created by making two cm midline incisions followed by inoculation of microorganisms. Study groups comprised of Sham (no treatment), PRP alone, MRSA alone, MRSA?+?PRP, MRSA?+?Vancomycin, and MRSA?+?Vancomycin?+?PRP groups. We inoculated 0.1 mL (3?×?10⁸ CFU/mL) of MRSA in contaminated groups. After 8 days, all rats were killed, wounds were excised and subjected to histopathologic examination, and MRSA counts were determined.

Results

MRSA counts in MRSA, MRSA?+?PRP, MRSA?+?Vancomycin and MRSA?+?Vancomycin?+?PRP groups were 5.1?×?10⁶ (SD?±?0.4) CFU/mL, 4.3?×?10⁶ (SD?±?0.7) CFU/mL, 2.3?×?10⁶ (SD?±?0.3) CFU/mL, 1.1?×?10⁶ (SD?±?0.4) CFU/mL, respectively. The inflammation scores of MRSA?+?PRP, MRSA?+?Vancomycin, and MRSA?+?Vancomycin?+?PRP groups were significantly lower than the MRSA group. MRSA?+?Vancomycin?+?PRP group inflammation score was significantly lower than the MRSA?+?PRP group.

Discussion

All treatment groups were effective in wound healing and decreasing the MRSA counts. MRSA?+?PRP combined created identical inflammation scores to the PRP group. More in vivo studies are required to corroborate these findings.

     

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.     

Strength training prior to muscle injury potentiates low-level laser therapy (LLLT)-induced muscle regeneration

We evaluated whether strength training (ST) performed prior to skeletal muscle cryolesion would act as a preconditioning, improving skeletal muscle regeneration and responsiveness to low-level laser therapy (LLLT). Wistar rats were randomly assigned into non-exercised (NE), NE plus muscle lesion (NE?+?LE), NE?+?LE plus LLLT (NE?+?LE?+?LLLT), strength training (ST), ST?+?LE, and ST?+?LE?+?LLLT. The animals performed 10 weeks of ST (climbing ladder; 3× week; 80% overload). Forty-eight hours after the last ST session, tibialis anterior (TA) cryolesion was induced and LLLT (InGaAlP, 660 nm, 0.035 W, 4.9 J/cm²/point, 3 points, spot light 0.028 cm², 14 J/cm²) initiated and conducted daily for 14 consecutive days. The difference between intergroups was assessed using Student’s t test and intragroups by two-way analysis of variance. Cryolesion induced massive muscle degeneration associated with inflammatory infiltrate. Prior ST improved skeletal regeneration 14-days after cryolesion and potentiated the regenerative response to LLLT. Cryolesion induced increased TNF-α levels in both NE?+?LE and ST?+?LE groups. Both isolated ST and LLLT reduced TNF-α to control group levels; however, prior ST potentiated LLLT response. Both isolated ST and LLLT increased IL-10 levels with no additional effect. In contrast, increased TA IL-6 levels were restricted to ST and ST?+?LE?+?LLLT groups. TA myogenin mRNA levels were not changed by neither prior ST or ST?+?LLLT. Both prior ST and LLLT therapies increased MyoD mRNA levels and, interestingly, combined therapies potentiated this response. Myf5 mRNA levels were increased only in ST groups. Taken together, our data provides evidences for prior ST potentiating LLLT efficacy in promoting skeletal muscle regeneration.     

Effect of photobiomodulation on connective tissue remodeling and regeneration of skeletal muscle in elderly rats

The purpose of this study was to evaluate the effects of low-level laser therapy (LLLT) on morphological aspects, IL-6 and IL-1β expressions, as well as the distribution and organization of collagen in the tibialis anterior (TA) muscle of elderly rats submitted to cryoinjury. Histological photomicrographs were taken of TA muscles stained with HE and picrosirius red. Immunohistochemistry was used for the evaluation of IL-6 and IL-1β. Male Wistar rats, aged 20 months, were distributed into three groups: (1) control animals not injured or treated with LLLT (n?=?5), (2) cryoinjury without LLLT treatment (n?=?15), and (3) cryoinjury treated with infrared LLLT (n?=?15). LLLT was applied to the TA 2 h after of the injury induction and consisted of daily applications until the sacrifice (1, 3, and 7 days). The following parameters were used: λ?=?780 nm, power density 1 W/cm², output power 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. In the histomorphological analysis, the treated group exhibited a significant decrease in inflammatory infiltrate (p?<?0.001) as well as an increase immature fibers and new blood vessels at 7 days compared to the untreated group (p?<?0.05). Furthermore, treatment induced a better collagen distribution and organization at 7 days in comparison to the untreated group (p?<?0.05). In conclusion, LLLT demonstrated a modulatory effect on the muscle repair process in elderly animals with regard to the collagen remodeling and morphological aspects of muscle tissue.     

Long-term low-level laser therapy promotes an increase in maximal oxygen uptake and exercise performance in a dose-dependent manner in Wistar rats

The use of low-level laser therapy (LLLT) represents a new intervention modality that has been explored to enhance exercise performance. The aim of this study was to evaluate the influence of LLLT (GaAIAs—850 nm) at different doses on VO_2max and on exercise performance in rats. Male Wistar rats were divided into three groups: “placebo” rats (P-LLLT, n?=?10), rats at a dose of 0.315 J per treatment point of LLLT (8.7 J/cm²-LLLT, n?=?10), and rats at a dose of 2.205 J per treatment point of LLLT (61.2 J/cm²-LLLT, n?=?10). The LLLT was applied bilaterally at the biceps femoris, gluteus, lateral and medial gastrocnemius, iliopsoas, and adductor longus muscles. One spot in each muscle belly was applied, with a sum of 12 spots in each rat, once a day, for 10 days. All animals performed the maximal exercise test (ET) at a metabolic treadmill for rats, with simultaneous gas analysis. The distance covered was measured during ET, before and after the conclusion of the LLLT protocol. The data were compared by a repeated measures two-way ANOVA followed by the Student-Newman-Keuls post hoc tests (p?<?.05). The 61.2 J/cm²-LLLT group increased VO_2basal (~40 %), VO_2max (~24 %), VCO_2max (~17 %), and distance covered (~34 %) after LLLT application on the skeletal muscle. No significant results were found comparing before and after conditions for the studied variables considering P-LLLT and 8.7 J/cm²-LLLT groups. The LLLT promoted in a dose-dependent manner an increase in oxygen consumption uptake and a performance increment of male Wistar rats.     

Muscle fiber conduction velocity and EMG amplitude of the upper trapezius muscle in healthy subjects after low-level laser irradiation: a randomized,double-blind,placebo-controlled,crossover study

Although low-level laser therapy (LLLT) is an important resource for the treatment of non-specific neck pain patients, the dose which presents the greatest therapeutic potential for the treatment of this pathology is still unclear. The present study aimed to evaluate the immediate effect of LLLT on the muscle fiber conduction velocity (MFCV) and electromyographic activity (EMG) of the upper trapezius (UT) muscle in healthy individuals. A total of 20 healthy subjects were enrolled in a randomized, double-blind, crossover study. Active LLLT (820 nm wavelength, 30 mW, energy total 18 J) or placebo LLLT (pLLLT) was delivered on the UT muscle. Each subject was subjected to a single session of active LLLT and pLLLT. Surface electromyography (sEMG) signal of the UT muscle was recorded during five different step contractions of shoulder elevation force (10–30% maximal voluntary contraction) pre- and post-LLLT irradiation. The values of MFCV and sEMG global amplitude (RMS_G) were used to calculate the effects of LLLT. The results showed no difference in the MFCV comparing the LLLT and pLLLT groups (F?=?0.72 p?=?0.39, η _p ²?=?0.004). However, a significant difference was observed in the RMS_G between the LLLT and pLLLT (F _1,2?=?16.66; P?<?0.0001, η _p ²?=?0.09). Individuals who received active LLLT presented a significant decrease in RMS_G after laser application (F?=?61.28; p?<?0.0001, η _p ²?=?0.43). In conclusion, the 820 nm LLLT, with energy total of 18 J, did not alter the MFCV but significantly reduced the sEMG signal amplitude of the upper trapezius muscle in healthy subjects to a level of up to 30% of maximal voluntary contraction.     

Cognitive enhancement by transcranial laser stimulation and acute aerobic exercise

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation and acute aerobic exercise on the same cognitive tasks. We examined whether transcranial infrared laser stimulation of the prefrontal cortex, acute high-intensity aerobic exercise, or the combination may enhance performance in sustained attention and working memory tasks. Sixty healthy young adults were randomly assigned to one of the following four treatments: (1) low-level laser therapy (LLLT) with infrared laser to two forehead sites while seated (total 8 min, 1064 nm continuous wave, 250 mW/cm², 60 J/cm² per site of 13.6 cm²); (2) acute exercise (EX) of high-intensity (total 20 min, with 10-min treadmill running at 85–90 % VO₂max); (3) combined treatment (LLLT + EX); or (4) sham control (CON). Participants were tested for prefrontal measures of sustained attention with the psychomotor vigilance task (PVT) and working memory with the delayed match-to-sample task (DMS) before and after the treatments. As compared to CON, both LLLT and EX reduced reaction time in the PVT [F(1.56)?=?4.134, p?=?0.01, η ² ?=?0.181] and increased the number of correct responses in the DMS [F(1.56)?=?4.690, p?=?0.005, η ² ?=?0.201], demonstrating a significant enhancing effect of LLLT and EX on cognitive performance. LLLT + EX effects were similar but showed no significantly greater improvement on PVT and DMS than LLLT or EX alone. The transcranial infrared laser stimulation and acute aerobic exercise treatments were similarly effective for cognitive enhancement, suggesting that they augment prefrontal cognitive functions similarly.     

Effect of laser and LED phototherapies on the healing of cutaneous wound on healthy and iron-deficient Wistar rats and their impact on fibroblastic activity during wound healing

Iron deficiency impairs the formation of hemoglobin, red blood cells, as well the transport of oxygen. The wound healing process involves numerous functions, many of which are dependent on the presence of oxygen. Laser has been shown to improve angiogenesis, increases blood supply, cell proliferation and function. We aimed to study the effect of λ660 nm laser and λ700 nm light-emitting diode (LED) on fibroblastic proliferation on cutaneous wounds on iron-deficient rodents. Induction of iron anemia was carried out by feeding 105 newborn rats with a special iron-free diet. A 1?×?1 cm wound was created on the dorsum of each animal that were randomly distributed into seven groups: I, control anemic; II, anemic no treatment; III, anemic?+?L; IV, anemic?+?LED; V, healthy no treatment; VI, healthy?+?laser; VII, healthy?+?LED (n?=?15 each). Phototherapy was carried out using either a diode laser (λ660 nm, 40 mW, 10 J/cm²) or a prototype LED device (λ700?±?20 nm, 15 mW, 10 J/cm²). Treatment started immediately after surgery and was repeated at 48-h interval during 7, 14, and 21 days. After animal death, specimens were taken, routinely processed, cut, stained with hematoxylin-eosin, and underwent histological analysis and fibroblast counting. Significant difference between healthy and anemic subjects on regards the number of fibroblast between treatments was seen (p?<?0.008, p?<?0.001). On healthy animals, significant higher count was seen when laser was used (p?<?0.008). Anemic subjects irradiated with LED showed significantly higher count (p?<?0.001). It is concluded that the use of LED light caused a significant positive biomodulation of fibroblastic proliferation on anemic animals and laser was more effective on increasing proliferation on non-anemics.     

Low-level laser therapy to recovery testicular degeneration in rams: effects on seminal characteristics,scrotal temperature,plasma testosterone concentration,and testes histopathology

The aim of this study was to investigate the efficiency of low-level laser therapy (LLLT) to recovery testicular degeneration in rams. In the first study, rams were induced to testicular degeneration by scrotal insulation, and then, they were treated using LLLT at 28 J/cm² (INS28) or 56 J/cm² (INS56) energy densities. Sperm kinetics, morphology, and membranes integrity as well as proportion of lumen area in seminiferous tubule were assessed. In the second study, rams were submitted or not to scrotal insulation and treated or not by the best protocol of LLLT defined by experiment 1 (INS28). In this study were evaluated sperm kinetics, morphology, membranes integrity, ROS production, and DNA integrity. Testosterone serum concentration and proportion of lumen area in seminiferous tubule were also analyzed. Insulation was effective in promoting sperm injuries in both experiments. Biostimulatory effect was observed in experiment 1: INS28 presented smaller proportion of lumen area (P?=?0.0001) and less degeneration degree (P?=?0.0002). However, in experiment 2, there was no difference between the groups (P?=?0.17). In addition, LLLT did not improve sperm quality, and there was a decreasing for total and progressive motility (P?=?0.02) and integrity of sperm membranes (P?=?0.01) in LLLT-treated groups. Moreover, testosterone concentration was not improved by LLLT (P?=?0.37). Stimulation of aerobic phosphorylation by LLLT may have led to a deregulated increase in ROS leading to sperm damages. Thus, LLLT at energy of 28 J/cm² (808 nm of wavelength and 30 mW of power output) can induce sperm damages and increase the quantity of cells in seminiferous tubule in rams.     

Low-level laser therapy in the management of plantar fasciitis: a randomized controlled trial

This study aimed at estimating the extent to which a combination therapy of low-level laser therapy (LLLT) with exercise and orthotic support (usual care) affects functional ability in the patient with plantar fasciitis (PF) when compared to usual care alone. Participants with PF were randomly allocated into two groups: LLLT (n?=?27) and control (n?=?22). All the participants received home exercise program with orthotic support. In addition, the LLLT group received a gallium-aluminum-arsenide laser with a 850-nm wavelength for ten sessions, three times a week. Functional outcomes were measured by function subscale of American Orthopedic Foot and Ankle Society Score (AOFAS-F) and 12-min walking test including walking speed, cadence, and activity-related pain using visual analog scale (VAS).The scores were recorded at baseline, third week, and third month after the treatment. Analysis was performed using repeated measures ANOVA and an intention to treat approach using multiple imputations. There was a significant improvement in AOFAS-F total score at 3 weeks in both groups (LLLT, p?<?0.001; control, p?=?0.002), but the improvements were seen only for the LLLT group for AOFAS-F total score (p?=?0.04) and two individual items of AOFAS-F (walking distance (p?<?0.001) and walking surface (p?=?0.01)) at 3 months. The groups were comparable with each other for both walking speed and cadence at all assessment times (p?>?0.05). Both groups showed significant reduction in pain over 3 months (LLLT, p?<?0.001; control, p?=?0.01); however, the LLLT group had lower pain than the control group at 3 months (p?=?0.03). The combination therapy of LLLT with usual care is more effective to improve functional outcomes and activity-related pain when compared to usual care alone.     

Effect of prior application with and without post-injury treatment with low-level laser on the modulation of key proteins in the muscle repair process

The aim of the present study was to evaluate the effects of LLLT prior to muscle injury with and without post-injury irradiation on the expression of isoforms of myosin heavy chain (MyHC), calcineurin (CaN), and myostatin during the repair process. Wistar rats were divided into five groups: control (n?=?7); injury (n?=?21); LLLT + injury (n?=?21); injury + LLLT (n?=?21), and LLLT + injury + LLLT (n?=?21). Cryoinjury was performed on the tibialis anterior (TA) muscle. The injured groups were euthanized at 3, 7, and 14 days after injury. LLLT was performed using an infrared laser (780 nm) with the following parameters: 10 J/cm², 40 mW, 10 s per point, 8 points, and 3.2 J of total energy. At the end of each period, the TA muscle was removed for the analysis of MyHC, CaN, and myostatin gene expression using real-time PCR. The data were tested statistically by Kruskal-Wallis with Dunn’s post hoc test (p?<?0.05). The results demonstrated that prior irradiation reduced the mRNA expression of all proteins at 3 days. Post irradiation reduced the mRNA expression of MyHC-1, MyHC-2a, MyHC-2b, and CaN at 7 days. Prior irradiation combined with post-injury irradiation reduced the mRNA expression of MyHC-2x and CaN at 14 days and increased the mRNA expression of myostatin in the same period. In conclusion, different protocols of photobiomodulation can modulate the expression of the different isoforms of MyHC, CaN, and myostatin during the repair process. It is noteworthy that the combination of the prior and post-injury irradiation was the protocol that most promoted changes in the final phase of the repair process.     

Red and infrared laser therapy inhibits in vitro growth of major bacterial species that commonly colonize skin ulcers

Low-level laser therapy (LLLT) is used in chronic wounds due to its healing effects. However, bacterial species may colonize these wounds and the optimal parameters for effective bacterial inhibition are not clear. The aim of this study was to analyze the effect of LLLT on bacterial growth in vitro. Bacterial strains including Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were suspended in saline solution at a concentration of 10³ cells/ml and exposed to laser irradiation at wavelengths of 660, 830, and 904 nm at fluences of 0 (control), 3, 6, 12, 18, and 24 J/cm². An aliquot of the irradiated suspension was spread on the surface of petri plates and incubated at 37 °C for quantification of colony-forming unit after 24, 48, and 72 h. Laser irradiation inhibited the growth of S. aureus at all wavelengths and fluences higher than 12 J/cm², showing a strong correlation between increase in fluence and bacterial inhibition. However, for P. aeruginosa, LLLT inhibited growth at all wavelengths only at a fluence of 24 J/cm². E. coli had similar growth inhibition at a wavelength of 830 nm at fluences of 3, 6, 12, and 24 J/cm². At wavelengths of 660 and 904 nm, growth inhibition was only observed at fluences of 12 and 18 J/cm², respectively. LLLT inhibited bacterial growth at all wavelengths, for a maximum of 72 h after irradiation, indicating a correlation between bacterial species, fluence, and wavelength.     

The effects of photobiomodulation and low-amplitude high-frequency vibration on bone healing process: a comparative study

This study aimed at investigating the effects of photobiomodulation (PBM) and low-amplitude high-frequency (LAHF) whole body mechanical vibration on bone fracture healing process when metallic plates are implanted in rats’ femurs. Forty male rats weighing between 250 and 350 g, 12 weeks old, were employed in this study. A transverse critical size defect (CSD) was made in their right femurs that were fixed by stainless steel plates. After the surgery, the rats were divided equally into four groups: low-level laser therapy group (GaAlAs laser, 830 nm, 40 mW, 4 J/cm², 0.35 cm beam diameter, LLLT), whole body vibration group (60 Hz, 0.1 mm amplitude, 1.5 g, WBV), a combination of laser and vibration group (LV), and the control group (C). Each group was divided into two subgroups based on sacrifice dates. The rats were sacrificed at intervals of 3 and 6 weeks after the surgery to extract their right femurs for radiography and biomechanical and histological analyses, and the results were analyzed using standard statistical methods. Radiographic analyses showed greater callus formation in the LLLT and WBV groups than in control group at both 3 (P?<?0.05 and P?<?0.001, respectively) and 6 weeks after surgery (P?<?0.05 and P?<?0.05, respectively). Histological evaluations showed a higher amount of new bone formation and better maturity in the LLLT and WBV groups than the control groups at 3 and 6 weeks after surgery. Biomechanical tests showed that the maximum force at fracture in the LLLT (P?<?0.05 in 3 weeks and P?<?0.05 in 6 weeks) and WBV (P?<?0.001 in 3 weeks and P?<?0.05 in 6 weeks) groups was greater than that in the control groups at both time intervals. But a combination of laser and vibration therapy, LV, did not show a positive interaction on bone fracture healing process. The biostimulation effects of PBM or LLLT and of low-amplitude high-frequency WBV both had a positive impact on bone healing process, for critical size defects in the presence of a stainless steel implant. But their combination, i.e., low-level laser therapy and low-amplitude high-frequency whole body vibration (LV), interestingly did not accelerate the fractured bone healing process.     

Low-level laser therapy stimulates tissue repair and reduces the extracellular matrix degradation in rats with induced arthritis in the temporomandibular joint

The objective of this study was to characterize morphological and biochemistry action of low-level laser therapy (LLLT) on induced arthritis in the temporomandibular joint (TMJ) of rats. Twenty-four male Wistar rats were randomly divided into groups with 12 animals each: (AG) group with arthritis induced in the left TMJ and (LG) group with arthritis induced in the left TMJ and treated with LLLT (830 nm, 30 mW, 3 J/cm²). Right TMJs in the AG group were used as noninjected control group (CG). Arthritis was induced by intra-articular injection of 50 μl Complete Freund’s Adjuvant (CFA) and LLLT began 1 week after arthritis induction. Histopathological analysis was performed using sections stained with hematoxylin-eosin, Toluidine Blue, and picrosirius. Biochemical analysis was determined by the total concentration of sulfated glycosaminoglycans (GAGs) and evaluation of matrix metalloproteinases (MMP-2 and MMP-9). Statistical analysis was performed using paired and unpaired t tests, with p?<?0.05. Compared to AG, LG had minor histopathological changes in the TMJ, smaller thickness of the articular disc in the anterior (p?<?0.0001), middle (p?<?0.0001) and posterior regions (p?<?0.0001), high birefringence of collagen fibers in the anterior (p?<?0.0001), middle (p?<?0.0001) and posterior regions (p?<?0.0001) on the articular disc, and statistically lower activity of MMP-2 latent (p?<?0.0001), MMP-2 active (P?=?0.02), MMP-9 latent (p?<?0.0001), and MMP-9 active (p?<?0.0001). These results suggest that LLLT can increase the remodeling and enhancing tissue repair in TMJ with induced arthritis.     

Low-level laser therapy combined to functional exercise on treatment of fibromyalgia: a double-blind randomized clinical trial

This study aims to investigate the effects of low-level laser therapy (LLLT) combined to a functional exercise program on treatment of FM. A double-blind and placebo-controlled randomized clinical trial composed of 22 women divided into two groups: placebo group (functional exercise program associated with placebo phototherapy n?=?11) and laser group (same exercise program associated with active phototherapy; n?=?11). Each session lasted from 40 to 60 min and was performed three times a week for 8 weeks. Phototherapy (808 nm, 100 mW, 4 J, and 142.85 J/cm² per point) was bilaterally applied to different points of the quadriceps (8), hamstrings (6), and triceps sural muscles (3) immediately after each exercise session. Pre- and post-intervention evaluations regarding pain (sites, intensity, and threshold), functional performance (balance, functional tests), muscle performance (flexibility and isokinetic variables), depression, and quality of life were conducted. A reduction in pain and improvement in functional and muscular performance, depression, and quality of life were observed in both groups (p?<?0.05); however, with no significant differences between them (p?>?0.05). In conclusion, the benefic effects of functional exercise were not improved by combination with LLLT.     

Increase in the nitric oxide release without changes in cell viability of macrophages after laser therapy with 660 and 808 nm lasers

The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) with different parameters and wavelengths on nitric oxide (NO) release and cell viability. Irradiation was performed with Ga-Al-As laser, continuous mode and wavelengths of 660 and 808 nm at different energy and power densities. For each wavelength, powers of 30, 50, and 100 mW and times of 10, 30, and 60 s were used. NO release was measured using Griess reaction, and cell viability was evaluated by mitochondrial reduction of bromide 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to formazan. LLLT promoted statistically significant changes in NO release and MTT value only at the wavelength of 660 nm (p?<?0.05). LLLT also promoted an increase in the NO release and cell viability when the energy densities 64 (p?=?0.04) and 214 J/cm² (p?=?0.012), respectively, were used. LLLT has a significant impact on NO release without affecting cell viability, but the significance of these findings in the inflammatory response needs to be further studied.     

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.