Effect Of Low-level Laser Research Articles

Effect of low level laser and low intensity pulsed ultrasound therapy on bone remodeling during orthodontic tooth movement in rats

BackgroundQuality bone regeneration, which leads to the improvement of bone remodeling, is essential for orthodontic treatment. In order to improve bone regeneration and increase the amount of tooth movement, different techniques have been implemented. The object of this study is to compare the effects of low-level laser therapy (LLLT), low-intensity pulsed ultrasound (LIPUS), and their combination on bone remodeling during orthodontic tooth movement.MethodsEighty (80) male, 6-week-old Sprague Dawley rats were grouped in to four groups, the first group was irradiated with (940 nm) diode laser, second group with LIPUS, and third group with combination of both LLLT and LIPUS. A forth group used was a control group in an incomplete block split-mouth design. The LLLT and LIPUS were used to treat the area around the moving tooth once a day on days 0–7, then the experiment was ended in each experimental endpoint (1, 3, 7, 14, and 21 days). For amount of tooth movement, models were imaged and analyzed. Histological examination was performed after staining with (hematoxylin and eosin) and (alizarin red and Alcian Blue) stain. One step reverse transcription-polymerase chain reaction RT-PCR was also performed to elucidate the gene expression of RANK, RANKL, OPG, and RUNX-2.ResultsThe amount of tooth movement, the histological bone remodeling, and the RT-PCR were significantly greater in the treatment groups than that in the control group. Among the treatment groups, the combination group was the highest and the LIPUS group was the lowest.ConclusionThese findings suggest that LLLT and LIPUS can enhance the velocity of tooth movement and improve the quality of bone remodeling during orthodontic tooth movement.

Use of low-level laser therapy on children aged 1 to 5 years with energy-protein malnutrition: A clinical trial.

Background:Episodes of malnutrition in early childhood can produces alterations in the salivary glands. The investigation of mechanisms that can reduce the impact of malnutrition on the defenses of the organism is of the utmost important and interest to public health. The aim of this study is to evaluate the effect of low-level laser on the saliva of children aged 1 to 5 years with energy-protein malnutrition.Methods:Mandatory inclusion criteria are diagnosis of malnutrition. The sample will consist of 50 men and women malnourished children aged 12 to 71 months. Saliva will be collected and the volume of saliva will be measured and the salivary flow rate will be determined (mL/min). Concentrations of salivary IgA in all samples will be measured using a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit. Low-level laser (laser diode) will be administered in the region of the parotid glands bilaterally as well as in the regions of the submandibular and sublingual glands.Discussion:This study will be the first that investigate the effects of local laser therapy on the salivary glands of malnourished children.Trial registration:Clinical.trials.gov as NCT03355313, first received in 21 November 2017.

The short-term effectiveness of low-level laser, phonophoresis, and iontophoresis in patients with lateral epicondylosis

Study DesignRandomized parallel group trial. IntroductionVarious treatment options for lateral epicondylosis have been reported in the literature. Purpose of StudyWe aimed to compare the effectiveness of low-level laser therapy (LLLT), phonophoresis, and iontophoresis in terms of pain, function, and grip strength. MethodsThis study that comprised 37 patients with lateral epicondylosis was planned as a prospective randomized parallel group trial. Twelve participants were randomized to the LLLT group, 12 to the phonophoresis group, and 13 to the iontophoresis group. The Visual Analog Scale (VAS), pressure algometer, the Patient-Rated Tennis Elbow Evaluation, and grip strength dynamometer were used to measure outcomes. The measurements were performed at baseline and at the end of 15 sessions. ResultsInvestigation of the pain scores revealed that all VAS scores were improved in both the laser and iontophoresis groups (VAS at rest: P = .015, effect size (ES) = 1.49 and P = .016, ES = 0.58, respectively; VAS during activity: P = .008, ES = 1.05 and P = .008, ES = 1.16, respectively; VAS at night: P = .013, ES = 1.01 and P = .016, ES = 0.72, respectively). Only advance in function and grip strength was associated with the iontophoresis group (Patient-Rated Tennis Elbow Evaluation P = .006, ES = 0.78; grip strength with elbow extension P = .011, ES = 1.03; with elbow flexion P = .003, ES = 0.52). DiscussionThe most effective approach could not be highlighted among the existing studies in the literature as they were applied in combination with other therapies. ConclusionIn our study, we observed that LLLT provides a benefit only for pain, whereas iontophoresis is beneficial for both pain and function. If the effect size is evaluated, LLLT is more influential than iontophoresis for decreasing pain. However, when we compared phonophoresis and iontophoresis in terms of effectiveness, we found that iontophoresis has better effects for pain, function, and grip strength.

Activation of the Immune Response of the Spleen by Using Low Level Laser (LLL) for Treatment of Mice Inoculated with Mammary Gland Carcinoma

Regional immune response with mammary gland carcinoma was studied statistically. However the prognostic value remains conflicting. This study was conducted on thirty normal mice which were inoculated with mammary gland carcinoma. The tumour size of the animals under study were measured before and after laser irradiation by using a vernier and compared with that of non irradiated animals with laser (control group). The aim of this study was to evaluate the effect of low level laser (LLL) on increasing the response of immune system by stimulating the spleen action to inhibit the cancer cell activity and then decrease the tumour size of inoculated mice. The results of the gross observation showed enlargement in the irradiated spleen in comparison with that of non irradiated ones. It could be said that the enlargement which occurred in the spleen proved that there was an increase in immune response by using laser stimulation. From this study, it may concluded that low level laser(LLL) was an efficient tool in stimulating the defense cells that found in the spleen which attack the cancer cells locally which resulted in decreasing the tumour size of the irradiated inoculated mice.

The effect of low-level laser 810 nm and light-emitting diode photobiomodulation (626 nm) on the stability of the implant and inflammatory markers interleukin-1 beta and prostaglandin E2, around implants

One of the most common problems in edentulous patients is the low stability of lower dentures. The most effective method to overcome this problem is implant-supported overdentures. After placing an implant, for the process of osseointegration to be complete and successful, it is better that patients do not use their denture for few months. This may be nonconvenient for patient because they are unable to speak and eat properly. The aim of this study was to evaluate the effect of low level laser (LLL) and light-emitting diode (LED) photobiomodulation on implant stability as well as their effect on interleukin-1 beta (IL-1β) and prostaglandin E2 (PGE2) biomarkers around implant in lower anterior region (over denture). In this clinical trial, 36 implants were placed in fully edentulous mandibles (12 people per person - three implants in areas of midline and canine). Each of the implants was randomly placed in one of three groups of laser, LED, and control. LLL (power of 50 mw and the amount of 20 J/cm2 for each implant) and LED with dose (20 mw/cm2) were irradiated on the day of surgery (zero), 3, 7, 10, and 14 days. The stability of implants was measured on the day of surgery and weeks 3, 4, and 8 after surgery with Periotest. The inflammatory biomarkers of IL-1β and PGE2 were also collected from gingival crevicular fluid around implants in 4 and 8 weeks. The collected data were analyzed by ANOVA statistical tests.pvalue<0.05 considered significant. The amounts of Periotest significantly increased 3rd week after surgery in the control group (P < 0.001). However, the laser group and LED group were associated with minimal changes, which indicates lower stability of implant in 3rd week in control group but no changes in stability of test groups (laser and LED). Laser and LED had no effect on the level of IL-1β and PGE2 in 4 and 8 weeks. The use of LLL or LED has a positive effect on the stability of the implants 3 weeks after surgery.

Anti-inflammatory effects of low-level laser in burn wound models in rats

Objective: The anti-inflammatory effects of low-level laser in burn wound model in rats were investigated. Design: Randomized controlled trial. Methods: The rats were assigned to three experimental groups. Group I received second-degree burn wounds; Group II received dressing film and low-level laser (1.2 J/cm 2 ) treatment after a burn wound; Group III received dressing film and low-level laser (2.3 J/cm 2 ) treatment after a burn wound. After inducing a deep second-degree burn wound, the wound was observed every day and the burn area diameter and retraction quantification at 1, 7, and 14 days were evaluated. Low-level laser was investigated on hematological parameters after 14 days. Effects of low-level laser on the inflammatory cytokines (tumor necrosis factor-α [TNF-α] and interleukin-6 [IL-6]) concentrations in the serum were evaluated using immunosorbent assay kits. Results: Group III showed a significant difference in wound size on days 7 and 14 compared to Group I (p<0.05). Group II showed a significant difference in wound size on day 14 compared to Group I (p<0.05). For wound contraction percentage, both laser therapy treatment groups showed a significant difference compared with Group I (p<0.05). There was also a significant difference in wound contraction percentage in Group III compared to Group II (p<0.05). Compared with the model control group, decreased TNF-α and IL-6 levels in the serum was observed at 14 days after burn wound induction. Conclusions: The results of this study suggest that low-level laser therapy can assist in burn wound healing, which might be associated with decreased concentrations of TNF-α and IL-6 related proinflammatory cytokines.

Laser-induced changes of in vitro erythrocyte sedimentation rate.

The study of the effects of low-level laser (LLL) radiation on blood is important for elucidating the mechanisms behind the interaction of LLL radiation and biologic tissues. Different therapy methods that involve blood irradiation have been developed and used for clinical purposes with beneficial effects. The aim of this study was to compare the effects of different irradiation protocols using a diode-pumped solid-state LLL (λ=405nm) on samples of human blood by measuring the erythrocyte sedimentation rate (ESR). Human blood samples were obtained through venipuncture into tubes containing EDTA as an anticoagulant. Every sample was divided into two equal aliquots to be used as an irradiated sample and a non-irradiated control sample. The irradiated aliquot was subjected to a laser beam with a wavelength of 405nm and an energy density of 72J/cm2. The radiation source had a fixed irradiance of 30mW/cm2. The ESR change was observed for three different experimental protocols: irradiated whole blood, irradiated red blood cells (RBCs) samples re-suspended in non-irradiated blood plasma, and non-irradiated RBCs re-suspended in irradiated blood plasma. The ESR values were measured after laser irradiation and compared with the non-irradiated control samples. Irradiated blood plasma in which non-radiated RBCs were re-suspended was found to result in the largest ESR decrease for healthy human RBCs, 51%, when compared with RBCs re-suspended in non-irradiated blood plasma. The decrease in ESR induced by LLL irradiation of the plasma alone was likely related to changes in the plasma composition and an increase in the erythrocyte zeta potential upon re-suspension of the RBCs in the irradiated blood plasma.

Effect of low level laser on dental pulp tissue during orthodontic movement

Low level laser application in orthodontics attempts to accelerate the induced orthodontic movement and to dissipate the dental discomfort during treatment. The recognition of its biological foundation is a fundamental issue to understand the effect of all tissues involved in the irradiated zone. There have been research findings on the cell proliferation and empowerment of cell functions, promotion of bone remodeling, and decreasing of the local swelling and pain during orthodontic treatments. However, the positive results of the laser application on cells involved in the orthodontic movement have not widely been investigated. Literature indicates a lack of research finding on the effect of low laser therapy on the dentin-pulp complex, which demands randomized controlled trials. For these reasons, the aim of this paper attempts to compile the main publications done regarding the effect of low level laser therapy on dental pulp tissue.

Comparative effectiveness of Low Level Laser therapy and Transcutaneous Electric Nerve Stimulation on Temporomandibular Joint Disorders.

Introduction: Temporomandibular joint disorders (TMDs) are the most common source of pain on the face. There are multiple etiologies, and several types of treatment have been reported. The use of non-invasive and reversible therapies in the treatment of such problems is recommended. The present study evaluated the effect of low-level laser (LLL) therapy and transcutaneous electric nerve stimulation (TENS) on TMDs. Methods: In this single-blind study, 40 patients with temporomandibular disorders were randomly divided into four groups: TENS (TENSTem dental), LLL (diode 810 nm CW), shamTENS, and sham-LLL. All subjects were examined and data on pain and tenderness in the temporomandibular joint (TMJ) and masticatory muscles (using the visual analogue scale) and mouth-opening (distance between incisal edges before feeling pain; mm) were collected before baseline (T1), after each session (T2-T5) and one month after the end of the sessions (T6)), and analyzed using repeated measure analysis of variance (ANOVA) and Bonferroni statistical tests. A P value < 0.05 was considered significant. Results: The decrease in pain (P=0.000), tenderness (P=0.000) and increase in mouth-opening ability (P=0.002) was greater in the TENS and LLL groups than in the placebo groups. At the one-month follow-up, significant decrease in pain and tenderness was recorded in the TENS and LLL groups (P=0.000). There was no significant differences between TENS and LLL and the placebo groups for maximum mouth-opening at the end of the study (P=0.692). Conclusion: Using TENS or LLL therapy can improve TMD symptoms at least for the short term. Although the effects of the placebo played a role in improving symptoms, their effects were less important.

A Comparative Study of 660 nm Low-Level Laser and Light Emitted Diode in Proliferative Effects of Fibroblast Cells.

Introduction: In recent years, low-power lasers have been widely used in medicine. With the introduction of affordable light emitted diode (LED), clinical application of LED light has become more and more popular. However, some researchers believe that due to lack of coherence of the LED light, it can be different in terms of biological effects, in comparison with laser. In this study, the biological effects of low-level laser (LLL) to those of LED light are compared and discussed. Methods: Human skin fibroblast cell line Hu02 was irradiated with LLL and LED light with a wavelength of 660 nm, power output of 35 mW and in continuous mode and the control group was not irradiated. The biological effects were compared through analysis of cell proliferation, production of reactive oxygen species (ROS) within the cell and rate of cell division. Results: Our findings showed that production of ROS within the cell was linearly increased both in the LED and laser light irradiated cells. However, laser light is more incremental in comparison to LED light. The MTT results showed that laser light at low energy density (less than 5 J/cm2) increased the rate of cell proliferation after 24 hours. Although, the rate of cell division was increased in energy density of 1 J/cm2 compared to the control group, this increase was not statistically significant. Discussion: The findings indicated that the coherence properties of laser light provided more energy for the cells, and in a constant energy density, laser light created more oxidative stresses in comparison with LED light.

OSTEOCLASTOGENIC POTENTIAL OF ORAL CARCINOMA CELLS CAN BE MODULATED BY LOW LEVEL LASER (LLL)

This study aimed to analyze the effect of low-level laser on the osteoclastogenic potential of a squamous cell carcinoma cell line (SCC9). Irradiated SCC9 cells (660 /780 nm; 40 /70 mW; 2, 4 and 6 J/cm2) were cultured with human osteoclast precursors (PBMC). Co-cultures with non-irradiated SCC9 cells served as control. After 7, 14 and 21 days, the co-cultures (treated or not with specific inhibitors of MEK, NFkB, p38 and JNK pathways) were evaluated for the tartrate-resistant acid phosphatase (TRAP) activity (commercial kit). Monocultures of SCC9 cells (irradiated or not) were analyzed for the expression of IL-11 and PTHrP (by PCR). Irradiated SCC9 cells+PBMC co-cultures presented a significant reduction in TRAP activity (especially with 780 nm, 70 mW irradiation). Regardless the intracellular signaling pathway inhibitor, the decrease in TRAP activity observed in the co-cultures involving irradiated SCC9 cells was more notorious with 780 nm-4 J/cm2-70 mW. SCC9 cells irradiated with a low output power (780 nm-4 J/cm2-40 mW and 660 nm-4 J/cm2-40 mW) and cultured for 2 days presented increased expression of IL-11 and PTHrP. In 9 days cultures, expression of these molecules was lower than in non-irradiated cells. Laser irradiation (780 nm/70 mw/4 J/cm2) of SCC9 cells is able to decrease the pro-osteoclastogenic potential of those cells.

Combine effect of Chondroitinase ABC and low level laser (660 nm) on spinal cord injury model in adult male rats

After spinal cord injury (SCI) there are many recoveries inhibiting factors such as chondroitin sulfate proteoglycan (CSPG) and inflammation. The present study investigated the combinational effect of low level laser therapy (LLLT) as anti-inflammatory agent and Chondroitinase ABC (ChABC) enzyme as CSPG digesting factor on spinal cord after injury. This study performed on 44 male Wistar rats, spinal cord injury induced by a clip compression injury. Animals received two-weeks treatment of 660nm low level laser (LLL) and intraspinal injection of 1μg ChABC. Functional recovery, cavity size, myelination, axonal projections around the cavity, fibroblast invasion and expression of glycogen synthase kinase-3β (GSk 3β), CSPG and aquaporin 4 (AQP4) expression were evaluated. In statistical evaluation p<0.05 considered significant. Result showed the combination of LLLT and ChABC have more effect on reduction of cavity size, improvement of myelination and number of axons around the cavity and decreasing the expression of GSK3β, CSPG and AQP4 expression compared to LLLT and ChABC alone. In the laser and laser+enzyme groups AQP4 expression decreased significantly after SCI. Functional recovery, improved in LLLT and ChABC treated animals, but higher recovery belonged to the combination therapy group. The current study showed combination therapy by LLLT and ChABC is more efficient than a single therapy with each of them.

Effect of low-level laser-treated mesenchymal stem cells on myocardial infarction.

Cardiovascular disease is the leading cause of death worldwide. Although cardiac transplantation is considered the most effective therapy for end-stage cardiac diseases, it is limited by the availability of matching donors and the complications of the immune suppressive regimen used to prevent graft rejection. Application of stem cell therapy in experimental animal models was shown to reverse cardiac remodeling, attenuate cardiac fibrosis, improve heart functions, and stimulate angiogenesis. The efficacy of stem cell therapy can be amplified by low-level laser radiation. It is well established that the bio-stimulatory effect of low-level laser is influenced by the following parameters: wavelength, power density, duration, energy density, delivery time, and the type of irradiated target. In this review, we evaluate the available experimental data on treatment of myocardial infarction using low-level laser. Eligible papers were characterized as in vivo experimental studies that evaluated the use of low-level laser therapy on stem cells in order to attenuate myocardial infarction. The following descriptors were used separately and in combination: laser therapy, low-level laser, low-power laser, stem cell, and myocardial infarction. The assessed low-level laser parameters were wavelength (635-804nm), power density (6-50mW/cm2), duration (20-150s), energy density (0.96-1J/cm2), delivery time (20min-3weeks after myocardial infarction), and the type of irradiated target (bone marrow or in vitro-cultured bone marrow mesenchymal stem cells). The analysis focused on the cardioprotective effect of this form of therapy, the attenuation of scar tissue, and the enhancement of angiogenesis as primary targets. Other effects such as cell survival, cell differentiation, and homing are also included. Among the evaluated protocols using different parameters, the best outcome for treating myocardial infarction was achieved by treating the bone marrow by one dose of low-level laser with 804 nm wavelength and 1J/cm2 energy density within 4h of the infarction. This approach increased stem cell survival, proliferation, and homing. It has also decreased the infarct size and cell apoptosis, leading to enhanced heart functions. These effects were stable for 6weeks. However, more studies are still required to assess the effects of low-level laser on the genetic makeup of the cell, the nuclei, and the mitochondria of mesenchymal stromal cells (MSCs).

Effect of Low-Level Laser and Light-Emitting Diode on Inferior Alveolar Nerve Recovery After Sagittal Split Osteotomy of the Mandible: A Randomized Clinical Trial Study.

The major concern of sagittal split osteotomy (SSO) is the neurosensory disturbance. The authors investigated the effect of low-level laser therapy and light-emitting diode on the inferior alveolar nerve recovery after SSO. In this double-blinded randomized clinical trial, 20 subjects with inferior alveolar nerve injury after SSO of the mandible were studied. Neurosensory recovery was assessed by 6 tests: visual analog scale (VAS), brush stroke, 2-point discrimination, contact detect detection, pinprick nociception, and thermal discrimination, and each one was performed before and after the surgery on days 1, 3, 7, 14, 60, and 180. After 1 week, the VAS score in the laser group significantly improved in comparison with the control group. Visual analog scale score improvement was 25% (P = 0.015) at 2 weeks, 21% (P = 0.001) at 2 months, and 24% (P = 0.001) at 6 months. After 2 weeks, the brush stroke score improvement was significant in the laser group. The improvement values were 21.5% (P = 0.002) at 2 months and 15.1% (P = 0.004) at 6 months. Low-level laser therapy and light-emitting diode may improve VAS scores, 2-point discrimination, and brush stroke test results without any effect on the pinprick or contact detection test results.

Effect of Low Level Laser on Nasal Mucosa Immunity of Rats with Six-week Incremental Exercise

Effect of Low Level Laser on Nasal Mucosa Immunity of Rats with Six-week Incremental Exercise

Dichromatic and monochromatic laser radiation effects on survival and morphology of Pantoea agglomerans

Despite the beneficial effects of low-level lasers on wound healing, their application for treatment of infected injuries is controversial because low-level lasers could stimulate bacterial growth exacerbating the infectious process. Thus, the aim of this work was to evaluate in vitro effects of low-level lasers on survival, morphology and cell aggregation of Pantoea agglomerans. P. agglomerans samples were isolated from human pressure injuries and cultures were exposed to low-level monochromatic and simultaneous dichromatic laser radiation to study the survival, cell aggregation, filamentation and morphology of bacterial cells in exponential and stationary growth phases. Fluence, wavelength and emission mode were those used in therapeutic protocols for wound healing. Data show no changes in morphology and cell aggregation, but dichromatic laser radiation decreased bacterial survival in exponential growth phase and monochromatic red and infrared lasers increased bacterial survival at the same fluence. Simultaneous dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation and simultaneous dichromatic laser could be the option for treatment of infected pressure injuries by Pantoea agglomerans.

Low-Level Laser Effect on Proliferation, Migration, and Antiapoptosis of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have been proved to be an important element in cell-based therapy. Photobiomodulation used extremely low-level lasers (LLLs) to affect the behavior of cells. The effect mechanism of LLLs on MSCs from human remained to be discovered. In this study, cell viability was assessed using MTS assays and cell cycle was evaluated by fluorescence-activated cell sorting (FACS). The influence of LLLs on mitochondrial biogenesis (fission or fusion) and function (ATP, reactive oxygen species [ROS], nitric oxide [NO]) was evaluated by transmission electron microscope, FACS, quantitative real time polymerase chain reaction (q-PCR), and immunocytochemistry. Cell migration and cytoskeleton alteration (actin and tubulin) were evaluated using transwell assay, immunocytochemistry, enzyme-linked immunosorbent assay, and western blotting. Cell apoptosis was evaluated using FACS, immunocytochemistry, and western blotting. We investigated that certain influence of LLLs on MSCs in vitro 6 or 24 h after 1 h of LLL irradiation. The mechanism of the effects included proliferation rate increase mediated by increased S phase proportion; mitochondrial biogenesis and function alteration mediated by fusion (Mfn1, Mfn2, and Opa-1) and fission (Fis1, Drp-1, and MTP18)-related proteins, NRF1, TFAM, PGC-1a, and upregulated intracellular ROS and NO concentration; migration acceleration through the ERK1/2 and FAK pathway and upregulation of growth factors such as HGF and PDGF; and resistance to apoptosis with increased Bcl-2 and decreased Bax, or through tunneling nanotube formation between LLL-treated MSCs and 5-fluorouracil-induced apoptotic MSCs. These observations suggested that LLLs enhanced stem cell survival and therapeutic function, which could appear to be an innovative pretreatment in the application of MSCs.

Effect of Low Level Laser versus McKenzie Technique in Treatment of Chronic Low Back Pain

Background: Lower back pain refers to the pain and discomfort, which is usually, localized in between costal margin and inferior gluteal folds. Occasionally it is accompanied with pain in the leg too. Patients: Forty five patients with chronic low back pain (mean age 40.5±years, height 167±cm, weight 82.5±kg, and BM 29±kg/m2) participated in this study. Patients and methods: Patients were categorized into 3 different equal groups (15 nos); group (A) received low level laser, group (B) received McKenzie technique and group(C) received traditional electrotherapy and functioned as the control group. Data of visual analogue scale (VAS), patient specific functional Scale and (ROM) scores were collected from each patient pre and post the administration of physiotherapy. Results: Statistical analysis using paired student t-test and unpaired student t-test showed significant differences in the VAS and PSFS values recorded pre and post treatment in both groups A and B. There was significant difference in improvement in pain; ROM and functional disability in laser group (A) than in McKenzie technique group (B). Conclusion: The physiotherapy program is not only effective for the patients having chronic lower back pain, it also helped in improving functional disability of the patients, especially when low level laser or McKenzie technique are added to the treatment program.

Effect of low-level laser on diabetic oral wound healing

IntroductionDelayed wound healing and higher risk for infection are common in diabetic than in nondiabetic individuals. The use of low-level laser therapy (LLLT) is a recent method that improves wound healing.Aim of the studyThis article aimed to study the effect of low-level laser application on th

The effects of low-level laser irradiation on breast tumor in mice and the expression of Let-7a, miR-155, miR-21, miR125, and miR376b.

Low-level laser therapy (LLLT) is a form of photon therapy which can be a non-invasive therapeutic procedure in cancer therapy using low-intensity light in the range of 450-800nm. One of the main functional features of laser therapy is the photobiostimulation effects of low-level lasers on various biological systems including altering DNA synthesis and modifying gene expression, and stopping cellular proliferation. This study investigated the effects of LLLT on mice mammary tumor and the expression of Let-7a, miR155, miR21, miR125, and miR376b in the plasma and tumor samples. Sixteen mice were equally divided into four groups including control, and blue, green, and red lasers at wavelengths of 405, 532, and 632nm, respectively. Weber Medical Applied Laser irradiation was carried out with a low power of 1-3mW and a series of 10 treatments at three times a week after tumor establishment. Tumor volume was weekly measured by a digital vernier caliper, and qRT-PCR assays were performed to accomplish the study. Depending on the number of groups and the p value of the Kolmogorov-Smirnov test of normality, a t test, a one-way ANOVA, or a non-parametric test was used for data analyses, and p < 0.05 was considered to be statistically significant. The average tumor volume was significantly less in the treated blue group than the control group on at days 21, 28, and 35 after cancerous cell injection. Our data also showed an increase of Let-7a and miR125a expression and a decrease of miR155, miR21, and miR376b expression after LLLT with the blue laser both the plasma and tumor samples compared to other groups. It seems that the non-invasive nature of laser bio-stimulation can make LLLT an attractive alternative therapeutic tool.