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.     

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.     

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.     

Low-level laser therapy with 940 nm diode laser on stability of dental implants: a randomized controlled clinical trial

Low-level laser therapy (LLLT) is a non-invasive modality to promote osteoblastic activity and tissue healing. The aim of this study was to evaluate the efficacy of LLLT for improvement of dental implant stability. This randomized controlled clinical trial was performed on 80 dental implants placed in 19 patients. Implants were randomly divided into two groups (n = 40). Seven sessions of LLLT (940 nm diode laser) were scheduled for the test group implants during 2 weeks. Laser was irradiated to the buccal and palatal sides. The same procedure was performed for the control group implants with laser hand piece in “off” mode. Implant stability was measured by Osstell Mentor device in implant stability quotient (ISQ) value immediately after surgery and 10 days and 3, 6, and 12 weeks later. Repeated measures ANOVA was used to compare the mean ISQ values (implant stability) in the test and control groups. Statistical test revealed no significant difference in the mean values of implant stability between the test and control groups over time (P = 0.557). Although the mean values of implant stability changed significantly in both groups over time (P < 0.05). Although the trend of reduction in stability was slower in the laser group in the first weeks and increased from the 6th to 12th week, LLLT had no significant effect on dental implant stability.     

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.     

Acute effects of low-level laser therapy irradiation on blood lactate and muscle fatigue perception in hospitalized patients with heart failure—a pilot study

The objective of the present study is to evaluate the acute effects of low-level laser therapy (LLLT) on functional capacity, perceived exertion, and blood lactate in hospitalized patients with heart failure (HF). Patients diagnosed with systolic HF (left ventricular ejection fraction <45 %) were randomized and allocated prospectively into two groups: placebo LLLT group (n?=?10)—subjects who were submitted to placebo laser and active LLLT group (n?=?10)—subjects who were submitted to active laser. The 6-min walk test (6MWT) was performed, and blood lactate was determined at rest (before LLLT application and 6MWT), immediately after the exercise test (time 0) and recovery (3, 6, and 30 min). A multi-diode LLLT cluster probe (DMC, São Carlos, Brazil) was used. Both groups increased 6MWT distance after active or placebo LLLT application compared to baseline values (p?=?0.03 and p?=?0.01, respectively); however, no difference was observed during intergroup comparison. The active LLLT group showed a significant reduction in the perceived exertion Borg (PEB) scale compared to the placebo LLLT group (p?=?0.006). In addition, the group that received active LLLT showed no statistically significant difference for the blood lactate level through the times analyzed. The placebo LLLT group demonstrated a significant increase in blood lactate between the rest and recovery phase (p?<?0.05). Acute effects of LLLT irradiation on skeletal musculature were not able to improve the functional capacity of hospitalized patients with HF, although it may favorably modulate blood lactate metabolism and reduce perceived muscle fatigue.     

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.     

Anti-inflammatory and lymphangiogenetic effects of low-level laser therapy on lymphedema in an experimental mouse tail model

The aim of the present study was to investigate the therapeutic mechanism of low-level laser therapy (LLLT) in the mouse tail lymphedema model. Six-week-old female mice were classified into the laser treatment group, sham treatment group, and surgical control group (10 mice per group). LLLT was administered daily for 10 min from the surgical day to 11 days (12 times). Macrophage activation and lymphatic vessel regeneration were evaluated through immunohistochemical staining with anti-F4/80 and anti-LYVE-1 antibodies, respectively, at 12 days post-procedure. Quantitative real-time polymerase chain reaction (qPCR) was performed to measure messenger RNA (mRNA) expression of vascular endothelial growth factor A, B, C, R1, R2, and R3 (VEGF-A, VEGF-B, VEGF-C, VEGFR1, VEGFR2, and VEGFR3) at 12 days post-procedure. Student’s t and one-way ANOVA tests were performed for statistical analyses. Significance was defined as p?<?0.05. The thickness of the tail rapidly increased until 6 days in the laser and sham groups. The mice in the laser group showed a significantly decreased thickness compared with the sham group at 10 and 12 days. Immunohistochemistry assay revealed that LLLT reduced inflammation and induced new lymphatic vessel growth. qPCR showed that expressions of VEGFR3 were (p?=?0.002) increased in the laser group. These results suggest that LLLT has anti-inflammatory and lymphangiogenetic effects for the management of lymphedema.     

Evaluation of laser therapy and alpha-lipoic acid for the treatment of burning mouth syndrome: a randomized clinical trial

The aim of this study was to evaluate the efficacy of low-level laser therapy (LLLT) and alpha-lipoic acid (ALA) in the treatment of burning mouth syndrome (BMS) and secondary oral burning (SOB) by unstimulated sialometry, symptom assessment, and measurement of salivary TNF-α levels. Forty-four patients were randomized into four treatment groups: BMS/laser (n =?10), BMS/ALA (n =?5), SOB/laser (n =?15), and SOB/ALA (n =?14). The control group consisted of eight healthy female subjects. Unstimulated salivary flow was measured before and after treatment, and the collected saliva was stored at ??20 °C for the analysis of TNF-α. Symptoms were evaluated before and after treatment using a pain visual analog scale. Most patients were women (81.8%) during menopause (72.2%). LLLT and ALA were efficient in increasing salivary flow only in BMS but provided symptom relief in both conditions. TNF-α levels did not differ between patients with BMS and SOB or between those patients and the control group. No differences were observed in posttreatment TNF-α levels in either condition. The results of this study suggest that LLLT and ALA are efficient therapies in reducing burning mouth symptoms, with LLLT being more efficient than ALA.     

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.     

Radiological and biochemical effects (CTX-II,MMP-3, 8, and 13) of low-level laser therapy (LLLT) in chronic osteoarthritis in Al-Kharj,Saudi Arabia

Inflammation of synovial membrane and degeneration of articular cartilage in osteoarthritis (OA) lead to major changes in joint space width (JSW) and biochemical components such as collagen-II telopeptide (CTX-II) and matrix metallo protineases (MMP-3, 8, and 13). Low-level laser therapy (LLLT) is thought to have an analgesic effect as well as biomodulatory effect on microcirculation and cartilage regeneration in animal studies. The objective of this study was to examine the analgesic and biochemical effect of LLLT in patients with knee osteoarthritis. Subjects (n?=?34) who fulfilled the selection criteria were randomly divided into active group (n?=?17) and placebo group. Subjects in active group were irradiated laser with the frequency of 3 days per week for 4 weeks with the specific parameters on 8 different points on the joint at 1.5 J per point for 60 s for 8 points for a total dose of 12 J in a skin contact method. The placebo group was treated with the same probe with minimum emission of energy. Visual analog scale for pain intensity, joint space width, collagen-II telopeptide, and matrix metallo protinease-3, 8, and 13 was measured before treatment and at 4 and 8 weeks following treatment. Data are analyzed with mean values and standard deviation with p?<?0.05. Baseline values of all outcome measures show insignificant difference (p?>?0.05) in both groups which shows homogeneity. After 4- and 8-week treatment, active laser group shows more significant difference (p?<?0.001) in all the parameters than the placebo laser group (p?>?0.05). Our results show that low-level laser therapy was more efficient in reducing pain and improving cartilage thickness through biochemical changes.     

Effects of low-level laser therapy on performance,inflammatory markers,and muscle damage in young water polo athletes: a double-blind,randomized, placebo-controlled study

This study aimed to evaluate the effects of 5 days of 810-nm low-level laser therapy (LLLT) intervention on inflammatory and muscle damage markers and performance in young water polo players. Twenty young male water polo players participated in the study, which was designed as a randomized, double-blinded, placebo-controlled trial. Active LLLT or an identical placebo LLLT were delivered to eight points on the adductor muscle region immediately after each training day. Performance was measured by a 200-m maximal swimming (P200) and a 30-s crossbar jump test (30CJ) which was performed every day before training, and blood samples were drawn pre and post the final LLLT intervention to measure interleukins (IL) and muscle damage markers. There was no significant change in the P200 exercise in the LLLT group compared with the placebo group but there was a moderate improvement in the 30CJ (8.7?±?2.6 %). IL-1β and tumor necrosis factor-alpha presented increased (P?<?0.016) concentration within group 48 h after the last LLLT intervention compared to pre, 0, and 24 h, but did not differ between groups. IL-10 increased over time in the placebo group and reached a moderate effect compared to the LLLT group. The creatine kinase decreased significantly (P?=?0.049) over the time within the LLLT treatment group, but there was no significant change in lactate dehydrogenase (P?=?0.150). In conclusion, LLLT resulted in a non-significant, but small to moderate effect on inflammatory and muscle damage markers and a moderate effect on performance in water polo players. In addition, the lack of positive results could be due to the small area covered by irradiation and this should be considered in future studies.     

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.     

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.     

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.     

Low-intensity laser (660 nm) on sternotomy healing in patients who underwent coronary artery bypass graft: a randomized,double-blind study

The aim of this study was to analyze the healing effects of low-level laser therapy (LLLT) on the longitudinal sternotomy incisions of patients who underwent coronary artery bypass graft (CABG). The volunteers were randomized into three groups of equal size (n?=?30): control, placebo, and laser (λ?=?660 nm and spatial average energy fluency [SAEF]?=?1.06 J/cm²). The patients in the laser group underwent irradiation on postoperative days 2, 4, 6, and 8, and their sternotomy incisions were photographed immediately after the surgery and 8 days later for analysis. Three researchers who were blinded to the patient treatment groups analyzed the incision photographs to assess hyperemia and wound closure on the day of hospital discharge (eighth postoperative day). The sternotomy incisions in the LLLT group demonstrated less hyperemia, incisional bleeding, and dehiscence (p?≤?0.005).     

Maximal oxygen uptake and exercise tolerance are improved in rats with heart failure subjected to low-level laser therapy associated with resistance training

Exercise tolerance and maximal oxygen uptake (VO_2max) are reduced in heart failure (HF). The influence of combined resistance training (RT) and low-level laser therapy (LLLT) on exercise tolerance and VO_2max in HF has not yet been explored. The aim of this study was to evaluate the influence of combined RT and LLLT on VO_2max and exercise tolerance in rats with HF induced by myocardial infarction (MI). Rats were allocated to sedentary sham (Sed-Sham, n?=?12), sedentary heart failure (Sed-HF, n?=?9), RT heart failure (RT-HF, n?=?7) and RT associated with LLLT heart failure (RT?+?LLLT-HF, n?=?7) groups. After MI or sham surgery, rats underwent a RT and LLLT protocol (applied immediately after RT) for 8 weeks. VO_2max and exercise tolerance were evaluated at the end of protocol. HF rats subjected to LLLT combined with RT showed higher VO_2basal (41 %), VO_2max (40 %), VO_2reserve (39 %), run distance (46 %), time to exhaustion (30 %) and maximal velocity (22 %) compared with HF rats that underwent RT alone. LLLT associated with RT improved oxygen uptake and exercise tolerance compared with RT alone in HF rats.     

Effects of low-level laser therapy on bone regeneration of the midpalatal suture after rapid maxillary expansion

This study evaluated the effect of low-level laser therapy (LLLT) on bone regeneration at the midpalatal suture (MPS) after rapid maxillary expansion (RME), using cone beam computed tomography. Fourteen 8–14-year-old patients with transverse maxillary deficiency underwent RME with a Hyrax-type expander activated with one full turn after installation and two half turn daily activations until achieving overcorrection. Patients were randomly assigned to either a control group (RME alone, n?=?4) or an experimental group (n?=?10) in which RME was followed by 12 LLLT sessions (GaAlAs, p?=?70 mW, λ?=?780 nm, Ø?=?0.04 cm²). Two tomographic images of the MPS were obtained—T0, after disjunction and T1, after 4 months. Bone regeneration was evaluated by measuring the optical density (OD) on the tomographic images using InVivo Dental 5.0 software. Data were analyzed by the paired Student’s t test (α?=?0.05 %). A statistically significant difference between T0 and T1 OD values was observed in the laser-treated group (p?=?0.00), but this difference was not significant in the control group (p?=?0.20). Intergroup comparison of OD values at T1 revealed higher OD in the laser-treated group (p?=?0.05). In conclusion, LLLT had a positive influence on bone regeneration of the midpalatal suture by accelerating the repair process.     

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.