Photobiomodulation transiently increases the spontaneous firing in the superficial layer of the rat spinal dorsal horn.

The therapeutic benefits of photobiomodulation (PBM) in pain management, although well documented, are accompanied by concerns about potential risks, including pain, particularly at higher laser intensities. This study investigated the effects of laser intensity on pain perception using behavioral and electrophysiological evaluations in rats. Our results show that direct laser irradiation of 1000 mW/cm2 to the sciatic nerve transiently increases the frequency of spontaneous firing in the superficial layer without affecting the deep layer of the spinal dorsal horn, and this effect reverses to pre-irradiation levels after irradiation. Interestingly, laser irradiation at 1000 mW/cm2, which led to an increase in spontaneous firing, did not prompt escape behavior. Furthermore, a significant reduction in the time to initiate escape behavior was observed only at 9500 mW/cm2 compared to 15, 510, 1000, and 4300 mW/cm2. This suggests that 1000 mW/cm2, the laser intensity at which an increase in spontaneous firing was observed, corresponds to a stimulus that did not cause pain. It is expected that a detailed understanding of the risks and mechanisms of PBM from a neurophysiological perspective will lead to safer and more effective use of PBM.

Photobiomodulation inhibits neuronal firing in the superficial but not deep layer of a rat spinal dorsal horn.

Photobiomodulation (PBM) has attracted attention as a treatment for chronic pain. Previous studies have reported that PBM of the sciatic nerve inhibits neuronal firing in the superficial layers (lamina I-II) of the spinal dorsal horn of rats, which is evoked by mechanical stimulation that corresponds to noxious stimuli. However, the effects of PBM on the deep layers (lamina III-IV) of the spinal dorsal horn, which receive inputs from innocuous stimuli, remain poorly understood. In this study, we examined the effect of PBM of the sciatic nerve on firing in the deep layers of the spinal dorsal horn evoked by mechanical stimulation. Before and after PBM, mechanical stimulation was administered to the cutaneous receptive field using 0.6-26.0 g von Frey filaments (vFFs), and vFF-evoked firing in the deep layers of the spinal dorsal horn was recorded. The vFF-evoked firing frequencies were not altered after the PBM for any of the vFFs. The inhibition rate for 26.0 g vFF-evoked firing was approximately 13 % in the deep layers and 70 % in the superficial layers. This suggests that PBM selectively inhibits the transmission of pain information without affecting the sense of touch. PBM has the potential to alleviate pain while preserving the sense of touch.

Low-Level Laser Therapy for Allergic Rhinitis: A Systematic Review and Meta-Analysis.

INTRODUCTION: Allergic rhinitis (AR) is a common allergic disorder that impairs social and physical functioning as well as quality of life. It is characterized by sneezing, rhinorrhea, congestion, and itching which respond suboptimally to drug therapy. Low-level laser therapy (LLLT) has anti-inflammatory and immunosuppressive properties that have shown promise in some studies. We aimed to systematically review LLLT's effectiveness in treating AR and meta-analyze our findings. METHODS: A systematic search of PubMed, Scopus, and Web of Science was conducted on November 24, 2023. All studies investigating LLLT on AR were included, and a pre-post meta-analysis of nasal symptoms (rhinorrhea, nasal congestion, nasal itching, and sneezing) in the LLLT-treated arm was conducted. Rhinoconjunctivitis quality of life questionnaire (RQLQ) scores before and after LLLT were also meta-analyzed alongside a pairwise meta-analysis of LLLT with placebo, acupuncture, steroids/antihistamines, and ultraviolet lasers. A random-effects model was used with a conservative pre-post correlation of 0.4 and standardized mean difference (SMD) as the effect size. RESULTS: Sixteen studies were included in this review, and we found that nasal symptoms are alleviated post-LLLT in people with AR (SMD: -1.4, 95 CI: [-2.07 to -1.13], p value <0.001). RQLQ scores were also reduced after LLLT (SMD = -0.72, 95 CI: [-0.94 to -0.50], p value <0.001), and very few adverse events were reported. This meta-analysis, however, had significant publication bias and heterogeneity. When compared to a placebo, LLLT did not significantly improve nasal symptoms (SMD: -0.69, p value = 0.167), which might mean the post-LLLT nasal symptom alleviation is due to a placebo effect. Comparisons to other treatment modalities were too few to deduce anything meaningful, although it does appear that LLLT is less effective than UV lasers. CONCLUSION: LLLT is most likely effective at alleviating nasal symptomology and has a low likelihood of adverse event incidence, yet more high-quality studies with larger sample sizes are needed to compare LLLT to a placebo to ensure its superiority to the placebo effect, as well as non-inferiority clinical trials to compare it to standard treatments.

Dental management of people with complex or rare inherited bleeding disorders.

Advances in haematological therapies for people with complex or rare inherited bleeding disorders (IBD) have resulted in them living longer, retaining their natural teeth with greater expectations of function and aesthetics. Dental management strategies need to evolve to meet these challenges. Utilising low level laser diode therapy to reduce pre-operative inflammation to reduce the intraoperative and postoperative burden on haemostasis is described in a case series of 12 patients. For these individuals who previously required further medical management to support haemostasis or experienced such prolonged haemorrhage sufficient to warrant hospital admission, haemostasis was achieved in the dental surgery such that they were able to return home with no further medical intervention or overnight stays. Global inequities in accessing novel treatments for complex or rare IBD necessitates a comprehensive understanding of the local haemostatic agents available to dentists and the most commonly used agents and techniques are described including the use of single tooth anaesthesia (STA). STA is a computerised delivery mechanism that allows routine dental procedures that would previously have required block injections needing factor replacement therapy to be undertaken safely and effectively with no additional haemostatic intervention. The challenges of inhibitors in oral surgery are explained and discussed although more research and evidence is required to establish new treatment protocols. The importance of establishing good dental health in the quality of life of people with complex or rare IBD is highlighted with respect to the dental specific impact that more novel therapies may have on people with IBD.

Low-level LASER therapy accelerates fungal lesions cicatrization by increasing the production of Th1 and Th2 cytokines.

Paracoccidioidomycosis (PCM) is a systemic mycosis with serious clinical consequences in which the use of antifungal drugs requires long-term treatment. Therefore, we studied the effect of low-level LASER therapy (LLLT) to evaluate its prospects as a complementary treatment for PCM and improve the clinical response to the disease. OBJECTIVES: Our study focused on the resolution of lesions caused by fungal infection using a subcutaneous air pouch model of infection. METHODS: We evaluated cell profile and cytokines, fungi viability, and the presence of fibroblasts and fibrocytes at the site of infection. Inoculation of P. brasiliensis (Pb) was performed using a subcutaneous air pouch model and the LLLT irradiation was performed on alternate days on the rear paws of mice for 10 days, after which the cells from the air pouch were collected and analyzed. RESULTS: In animals irradiated with LLLT, the influx of cells to the air pouch was reduced, but they were more activated and produced pro-inflammatory (IL-12, IL-17 and TNF-α) and neutrophil (PMN) activating cytokines (IL-8, GM-CSF and γ-IFN). A better resolution of the infection, evidenced by the reduction in the number of viable fungi with preserved morphology in the air pouch, and an increase in the number of fibrocytes, indicating a healing profile were also observed. CONCLUSION: LLLT decreased the influx of PMN, but those presents were highly activated, with increased fungicidal activity. LLLT irradiation also resulted in earlier cicatrization at the site of infection, leading to a better outcome of the infection. These data are favorable to the use of LLLT as a complementary therapy in PCM.

Impact of low-level laser therapy on the quality of life of patients with xerostomia undergoing head and neck radiotherapy: a systematic review.

PURPOSE: To carry out a systematic review to assess whether low-level laser therapy can improve the quality of life of patients with xerostomia undergoing head and neck radiotherapy. METHODS: A systematic search was performed through Embase, Medline/PubMed, Cochrane, Scopus, Web of Science, nonpeer-reviewed clinicaltrials.gov and LILACS. The strategy included clinical studies were selected that prospectively followed or evaluated the quality of life by directly comparing the use of low-level laser therapy for xerostomia induced by head and neck radiotherapy with alternative therapies without the use of a laser. The risk of bias in the studies was assessed by RoB 2.0 and Robins I. RESULTS: After all application of the predetermined criteria, four studies were included, dated between the years 2014 and 2023. Three studies described as randomized clinical trials were included, one of which was a randomized pilot study and only one was a prospective clinical trial. A total of 126 patients were evaluated, all four studies used the infrared wavelength, with two studies using the combination with the red wavelength. It was observed that low-level laser therapy can change the sensation of dry mouth, improving patients' quality of life. In addition, changes related to increased stimulated and unstimulated salivary flow were also identified. CONCLUSION: The use of low-level laser therapy has promising results on xerostomia, consequently improving the quality of life of patients undergoing radiotherapy in the head and neck region.

Photobiomodulation for melasma treatment: Integrative review and state of the art.

PURPOSE: Photobiomodulation therapy (PBM) is a versatile technique for treating skin diseases. Melasma, a chronic hyperpigmentation condition, has recently been associated with vascular features and dermal photoaging and poses significant management challenges. We review the recent literature on melasma etiology and the evidence supporting PBM as a therapeutic modality for melasma treatment. METHODS: We conducted a comprehensive literature search in three different databases from May to August 2023, focusing on studies published in the past 10 years. The inclusion criteria comprised full-text studies investigating low-power lasers and/or light-emitting diodes (LEDs) in in vitro or in vivo models, as well as clinical trials. We excluded studies discussing alternative melasma therapies or lacking experimental data. We identified additional studies by searching the reference lists of the selected articles. RESULTS: We identified nine relevant studies. Clinical studies, in agreement with in vitro experiments and animal models, suggest that PBM effectively reduces melasma-associated hyperpigmentation. Specific wavelengths (red: 630 nm; amber: 585 and 590 nm; infrared: 830 and 850 nm) at radiant exposures between 1 and 20 J/cm2 exert modulatory effects on tyrosinase activity, gene expression, and protein synthesis of melanocytic pathway components, and thus significantly reduce the melanin content. Additionally, PBM is effective in improving the dermal structure and reducing erythema and neovascularization, features recently identified as pathological components of melasma. CONCLUSION: PBM emerges as a promising, contemporary, and non-invasive procedure for treating melasma. Beyond its role in inhibiting melanogenesis, PBM shows potential in reducing erythema and vascularization and improving dermal conditions. However, robust and well-designed clinical trials are needed to determine optimal light parameters and to evaluate the effects of PBM on melasma thoroughly.

Preventive and reparative effects of low-level laser therapy on orthodontically induced inflammatory root resorption-An animal study.

BACKGROUND: Orthodontically induced inflammatory root resorption (OIIRR) is one of the most important side effects of orthodontic treatment. Low-level laser therapy (LLLT) is a useful way to reduce the orthodontic treatment duration and may have some effect on preventing and repairing OIIRR. However, the specific effects of LLLT on OIIRR remain unknown. OBJECTIVE: Our research aimed to evaluate the Dentin Sialophosphoprotein (DSPP) expression level and root resorption volume during treatment and retention to explore the role of LLLT in preventing and repairing OIIRR. METHODS: Thirty-seven 6-week-old male Sprague-Dawley rats were selected to establish an OIIRR model; the rats were divided into Group B (blank), Group F (force), Group F(LLLT) (force and LLLT), Group F+R (force and retention) and Group F+R(LLLT) (force, retention and LLLT). The root resorption volume of the distal buccal root and mesial root in the maxillary left first molar was calculated by micro-CT, and the DSPP expression level on the compression side of the periodontal ligament was analysed by immunohistochemical staining. RESULTS: The resorption volume in Group F was greater than that in Group F(LLLT). For the mesial root, the volume in Group F was greater than that in Groups F+R and F+R(LLLT). For the distal buccal root, the volume in Groups F and F+R was greater than that in Group F+R(LLLT). The DSPP level in Group F(LLLT) was greater than that in Group F and there was no difference between Groups F+R and F+R(LLLT). CONCLUSIONS: LLLT has a certain preventive effect and a limited reparative effect on OIIRR in rats.

Efficacy of laser adjuvant therapy in the management of post-operative endodontic pain: A systematic review and meta-analysis.

BACKGROUND: Postoperative endodontic pain (PEP) is crucial in clinical practice. Recently, the effects of various laser adjuvant therapies in endodontic treatments have been widely evaluated. However, as a virtually side-effect-free treatment, its effect on postoperative pain management during endodontic treatment remains controversial. OBJECTIVES: This review aimed to compare the efficacy of laser adjuvant therapy for pain management after endodontic treatment. METHOD: The Cochrane Library, PubMed, Embase, Scopus and Web of Science databases were systematically searched for articles published until 12 February 2023. The risk of bias in the included studies was evaluated based on the Cochrane risk-of-bias assessment tool. Data on continuous outcomes of visual analogue scale pain scores are expressed as standard mean difference (SMD) and dichotomous outcomes of pain prevalence as relative risk (RR). RESULTS: We included 22 studies, of which 15 enrolled 892 patients with visual analogue scale pain scores and 7 enrolled 422 patients with pain prevalence. Of the 22 studies, seven studies had a low risk of bias, 10 had a moderate risk of bias and 5 had a high risk of bias. For pain level, the pooled outcomes indicated reduced pain scores in all laser adjuvant therapy, including low-level laser therapy (SMD = -0.86 [95% CI: -1.16, -0.55] in 24 h and SMD = -0.64 [95% CI: -0.84, -0.43] in 48 h), diode laser therapy (SMD = -0.27 [95% CI: -0.50, -0.04] in 48 h) and photodynamic therapy (SMD = -1.12 [95% CI: -2.18, -0.05] in 24 h). For postoperative pain incidence, a significant correlation was observed with reduced pain incidence rates in the photodynamic therapy group (pooled RR = 0.47 [95% CI: 0.31, 0.72]) but not in the low-level laser therapy group (RR = 0.89 [95% CI: 0.30, 2.70] at 12 h and RR = 0.57 [95% CI: 0.09, 3.72] at 24 h). CONCLUSIONS: High-quality evidence suggests that laser adjuvant therapies such as low-level laser therapy, diode laser therapy and photodynamic therapy have a positive impact on reducing postoperative endodontic pain intensity. However, the differences in PEP management effects between laser therapies are unknown, and no significant differences were observed among the subgroups. REGISTRATION: CRD 42023402872 (PROSPERO).

Photobiomodulation Therapy: A Novel Therapeutic Approach to Alzheimer's Disease Made Possible by the Evidence of a Brain-Gut Interconnection.

The evidence of brain-gut interconnections in Alzheimer's disease (AD) opens novel avenues for the treatment of a pathology for which no definitive treatment exists. Gut microbiota and bacterial translocation may produce peripheral inflammation and immune modulation, contributing to brain amyloidosis, neurodegeneration, and cognitive deficits in AD. The gut microbiota can be used as a potential therapeutic target in AD. In particular, photobiomodulation (PBM) can affect the interaction between the microbiota and the immune system, providing a potential explanation for its restorative properties in AD-associated dysbiosis. PBM is a safe, non-invasive, non-ionizing, and non-thermal therapy that uses red or near-infrared light to stimulate the cytochrome c oxidase (CCO, complex IV), the terminal enzyme of the mitochondrial electron transport chain, resulting in adenosine triphosphate synthesis. The association of the direct application of PBM to the head with an abscopal and a systemic treatment through simultaneous application to the abdomen provides an innovative therapeutic approach to AD by targeting various components of this highly complex pathology. As a hypothesis, PBM might have a significant role in the therapeutic options available for the treatment of AD.

Photobiomodulation on shoulder and neck pain and disability: A comprehensive review.

The purpose of this review was to evaluate the effect of Photobiomodulation (PBM) in managing shoulder and neck pain and disability. A literature search was conducted using the PubMed and ScienceDirect/EMBASE databases. The keywords used were "Low-level laser therapy", "photobiomodulation", "LASER", combined with "shoulder" or "neck". Only clinical studies written in English, Portuguese, Spanish, Italian, French, and German, were included. The review included 36 studies applying PBM therapy to alleviate pain or disability in patients with shoulder and neck conditions. Of these, 12 studies focused on neck conditions, and 24 studies addressed shoulder conditions, with one study concurrently examining both areas. This review on PBM therapy for shoulder and neck conditions shows promising results, particularly in pain relief and functional improvements, with infrared wavelengths being the most commonly used. Subacromial Impingement Syndrome (SAIS) and Myofascial Pain Syndrome (MPS) were the most frequently studied conditions. However, chronic and complex conditions like cervical osteoarthritis and post-stroke shoulder pain were less frequently represented, indicating a research gap. PBM was found to be a safe and non-invasive therapeutic option. Despite positive outcomes, variability in PBM protocols remains a challenge. Further standardized trials are needed to confirm its effectiveness across diverse conditions. This review updates current knowledge, highlights key findings, and provides direction for future research and clinical applications.

Evaluation of the efficacy of low-level laser therapy in the treatment of ulnar neuropathy at the elbow in terms of symptoms and clinical and electrophysiological findings: a randomized, prospective, double-blind clinical trial.

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy and presents with symptoms such as pain, paresthesia, and weakness in the elbow. Provocative tests and electrophysiological examinations are helpful in the diagnosis of UNE. Low-level laser therapy is one of the conservative treatments of UNE however, limited results were reported on the effectiveness of low-level laser therapy (LLLT) in the treatment of UNE. In our study, we aimed to the efficacy of LLLT in reducing symptoms and providing clinical and electrophysiological improvement in patients with UNE. This study with a randomized-sham controlled, and double-blind design included 68 patients aged 18-60 years who were diagnosed with UNE. LLLT was applied to the first group, and sham laser was applied to the second group. The VAS pain, paresthesia, and weakness scores, grip strength, and provocative test positivity were evaluated in clinical examination. The QuickDASH questionnaire was administered to assess functional status. Electrophysiologically, motor distal latency (MDL) differences, sensory distal latency (SDL), motor and sensory nerve conduction velocity (NCV) were examined. Evaluations were performed before treatment and on the 15th day and at the third month after treatment. The LLLT group showed improvement in symptoms, clinical findings, motor NCV, and MDL at both post-treatment evaluations and sensory NCV on the post-treatment 15th day (p < 0.05). The comparison of post-treatment changes between the two groups revealed that the LLLT group had greater improvement in VAS day and night pain scores at both post-treatment evaluation times, QuickDASH scores at the third month, and sensory NCV on the 15th day (p < 0.05) compared to the SL group. There were no significant differences between the groups in terms of the post-treatment changes in VAS weakness scores, grip strength and electrophysiological findings (p > 0.05). It was observed that splinting alone was effective in UNE, but the addition of LLLT, one of the conservative treatment methods, enhanced treatment outcomes.

Adjunctive photobiomodulation to Basic Periodontal therapy using different low-power laser application techniques: a systematic review and meta-analysis.

To review current literature and synthesize clinical outcomes related to different low-level laser techniques as a complement to basic periodontal therapy (BPT). Electronic searches were conducted in PubMed, Cochrane, and Scopus, and clinical trials published from January 2013 to August 2023 using photobiomodulation as a complement to basic periodontal therapy, with a clear description of the laser technique, were included. The risk of bias was assessed using the Joanna Briggs Institute Critical Assessment Checklist. Estimates of interest were calculated using random effects meta-analyses. A total of 947 references were retrieved, and 22 studies were included for qualitative synthesis. Ten studies used intrasulcular laser techniques, with 89% using infrared wavelength, and 12 studies used transgingival techniques, with 61.5% using red wavelength. The frequency of photobiomodulation after BPT ranged from 1 to 9 sessions, with follow-up periods ranging from 5 days to 12 months. Risk of bias was considered low in 16 studies and moderate in six studies. Meta-analysis of 13 studies showed that BPT reduced probing depth at 4-, 12- and 24-weeks post-treatment, and improved clinical level attachment at 6-, 12- and 24-weeks post-treatment. Studies suggest that photobiomodulation may be a valuable complement in the treatment of periodontitis, especially using transgingival application technique.

Expediting the reversal of inferior alveolar nerve block anesthesia in children with photobiomodulation therapy.

In pediatric dentistry, complications arising from extended soft tissue anesthesia can negatively impact patient comfort and trust in dental care. This study evaluates the clinical efficacy of diode laser-based photobiomodulation therapy (PBMT) in expediting the resolution of anesthesia in children aged 6-9 receiving inferior alveolar nerve block (IANB) injections. In this split-mouth double-blind randomized clinical trial, 36 pediatric subjects aged 6-9, requiring pulpotomy procedures on both sides of the mandible, received IANBs (single cartridge of 2% lidocaine/1:100,000 epinephrine). PBMT and sham laser were alternately applied to each side of the mandible, in two separate sessions, with the envelope method determining treatment allocation and intervention side on the first treatment day. During the laser session, laser (808 nm, 250 mW, 23s continuous, 0.5 cm², 11.5 J/cm², direct contact) irradiated two points at the injection site, five intra-oral and five extra-oral points along the infra-alveolar nerve's pathway. Soft tissue anesthesia reversal was quantified through tactile assessment. Soft tissue trauma was also assessed by the researcher and reported by parents 24 h post-dental visit. All data were analyzed using IBM SPSS Statistics v25.0 via Paired T-test, two-way repeated measures ANOVA, and McNemar's test. The laser group exhibited a mean lip anesthesia duration of 122.78 ± 2.26 min, while the sham laser group experienced 134.44 ± 21.8 min, indicating an 11.66-minute reduction in anesthesia duration for the laser group. (P < 0.001) Soft tissue trauma occurred in two sham laser group patients and one laser group patient, with no significant difference. (P = 1) The findings indicate that employing laser with defined parameters can reduce the length of IANB-induced anesthesia.

Investigation of the efficacy of two different laser types in the treatment of lower lip paresthesia after sagittal split ramus osteotomy.

Orthognathic surgery involves invasive and major surgical procedures commonly used to correct maxillofacial deformities. Bilateral sagittal split ramus osteotomy (BSSO) is often used to treat dentofacial anomalies related to the mandible, but it can result in various complications, the most common of which is inferior alveolar nerve damage. Nerve damage-induced paresthesia of the lower lip significantly affects patient comfort. Medical treatments such as steroids and vitamin B, low-level laser therapy (LLLT), and platelet-rich fibrin (PRF) can be used as supportive therapies for nerve regeneration after damage. This study aimed to investigate the effectiveness of two different types of lasers in treating lower lip paresthesia after BSSO. This clinical trial was a controlled, single-center, prospective, single-blind, randomized study. Thirty patients were included in the study and randomly assigned to three groups: Group I (laser GRR, n = 10) received transcutaneous and transmucosal GRR laser treatment, Group II (Epic10 laser, n = 10) received transmucosal and transcutaneous Epic10 laser treatment, and Group III (vitamin B, n = 10) received B-complex vitamin tablets orally once a day. Two-point and brush tests were performed six times at specific intervals, and a visual analog scale was used to evaluate pain and sensitivity. Both vitamin B and laser therapies accelerated nerve regeneration. The contribution of the laser groups to the healing rate was better than that of the vitamin B group. Although there was no statistically significant difference between the two laser groups, clinical observations indicated better results in the GRR laser group.

Effectiveness of photobiomodulation and orofacial myofunctional therapy in orofacial pain disorders. A systematic review of randomized control trials.

Orofacial pain can significantly affect physical, psychological, and overall quality of life. This study aimed to compare the effectiveness of combining photobiomodulation (PBM) with orofacial myofunctional therapy (OMT) in managing orofacial pain disorders. An electronic search of randomized controlled trials in electronic databases was performed until March 2024. Randomized controlled trials (RCTs) focusing on PBM and OMT for the management of orofacial pain were included. Risk of bias across individual studies was performed using the Cochrane risk of bias tool for interventions. A total of 10 RCTs were included, out of which 7 RCTs revealed that the combined approach of PBM and OMT had a more pronounced impact on diminishing pain and enhancing functional activity in patients with orofacial disorders. One study reported significant increases in pressure pain threshold for TMJ, masseter, and anterior temporalis muscles at both sides in the post-treatment compared with the pre-treatment in both groups. The risk of bias was low in 7, moderate in 2, and high in 1 study. The efficacy of a combined modality treatment of PBM with OMT for orofacial pain disorder shows promising results. However, further randomized controlled trials with extended follow-up periods standardized PBM and OMT parameters are warranted to obtain firm conclusions.

In-vitro study on type I collagen synthesis in low-level laser therapy on the early ligament fibroblasts' healing process.

BACKGROUND: Low-level Laser Therapy (LLLT) has demonstrated its potential in promoting fiber matrix maturation, collagen synthesis, and fibroblast proliferation, contributing to tissue regeneration. Our study aimed to investigate the impact of LLLT on collagen type I synthesis, cell proliferation, and viability in human ligament fibroblasts derived from the Anterior Cruciate Ligament (ACL). METHODS: Tissue samples were obtained from individuals undergoing arthroscopic ACL reconstruction surgery. Primary human fibroblasts were isolated, and immunohistochemical assays confirmed their characteristics. LLLT at 850 nm was administered in three groups: Low dose (1.0 J/cm²), High dose (5.0 J/cm²), and Control (0.0 J/cm²). Cell viability was calculated using a membrane integrity assay, proliferation was determined by automated counting, and collagen type I concentration in cell culture was measured using an immunoassay. RESULTS: Fibroblasts showed decreased viability after low and high doses of LLLT, increased proliferation at the low dose, and increased collagen synthesis at the high dose on day 10 for both sexes after treatment. CONCLUSION: Our study demonstrated that LLLT may improve the early ligament healing process by increasing cell proliferation at the low dose and enhancing collagen type I synthesis at the high dose in human ligament fibroblasts.

Osteoblastic differentiation and changes in the redox state in pulp stem cells by laser treatment.

The aim of this study was to determine the effect of low-level laser therapy (LLLT) on cell proliferation, mitochondrial membrane potential changes (∆Ψm), reactive oxygen species (ROS), and osteoblast differentiation of human dental pulp stem cells (hDPSCs). These cells were irradiated with 660- and 940-nm lasers for 5 s, 50 s, and 180 s. Cell proliferation was assessed using the resazurin assay, cell differentiation by RUNX2 and BMP2 expression, and the presence of calcification nodules using alizarin-red S staining. ROS was determined by the dichlorofluorescein-diacetate technique and changes in ∆Ψm by the tetramethylrhodamine-ester assay. Data were analyzed by a Student's t-test and Mann-Whitney U test. The 940-nm wavelength for 5 and 50 s increased proliferation at 4 days postirradiation. After 8 days, a significant decrease in proliferation was observed in all groups. Calcification nodules were evident in all groups, with a greater staining intensity in cells treated with a 940-nm laser for 50 s, an effect that correlated with increased RUNX2 and BMP2 expression. ROS production and Δψm increased independently of irradiation time. In conclusion, photobiomodulation (PBM) with LLLT induced morphological changes and reduced cell proliferation rate, which was associated with osteoblastic differentiation and increased ROS and Δψm, independent of wavelength and time.

Potential of combined red and near-infrared photobiomodulation to mitigate pro-osteoclastic and inflammatory gene expression in human mandibular osteogenic cells.

Appropriate regeneration of jawbone after dental or surgical procedures relies on the recruitment of osteoprogenitor cells able to differentiate into matrix-producing osteoblasts. In this context, photobiomodulation (PBM) has emerged as promising therapy to improve tissue regeneration and to facilitate wound healing processes. The aim of this study was to determine the effect of PBM on human osteoprogenitor cells isolated from mandibular trabecular bone.Bone marrow stromal cell cultures were established from 4 donors and induced toward osteogenic differentiation for 14 days in a standard osteogenic assay. Cells were irradiated with a combined red/near-infrared (NIR) laser following different schedules and expression of osteogenic, matrix-related, osteoclastogenic and inflammatory genes was analyzed by quantitative PCR.Gene expression analysis revealed no overall effects of PBM on osteogenic differentiation. However, a statistically significant reduction was observed in the transcripts of COL1A1 and MMP13, two important genes involved in the bone matrix homeostasis. Most important, PBM significantly downregulated the expression of RANKL, IL6 and IL1B, three genes that are involved in both osteoclastogenesis and inflammation.In conclusion, PBM with a red/NIR laser did not modulate the osteogenic phenotype of mandibular osteoprogenitors but markedly reduced their expression of matrix-related genes and their pro-osteoclastogenic and pro-inflammatory profile.

Effect of photobiomodulation therapy on the morphology, intracellular calcium concentration, free radical generation, apoptosis and necrosis of human mesenchymal stem cells-an in vitro study.

The aim of the study was to investigate the impact of multiwave locked system (MLS M1) emitting synchronized laser radiation at 2 wavelength simultaneous (λ = 808 nm, λ = 905 nm) on the mesenchymal stem cells (MSCs). Human MSCs were exposed to MLS M1 system laser radiation with the power density 195-318 mW/cm2 and doses of energy 3-20 J, in continuous wave emission (CW) or pulsed emission (PE). After irradiation exposure in doses of energy 3 J, 10 J (CW, ƒ = 1000 Hz), and 20 J (ƒ = 2000 Hz), increased proliferation of MSCs was observed. Significant reduction of Fluo-4 Direct™ Ca2+ indicator fluorescence over controls after CW and PE with 3 J, 10 J, and 20 J was noticed. A decrease in fluorescence intensity after the application of radiation with a frequency of 2000 Hz in doses of 3 J, 10 J, and 20 J was observed. In contrary, an increase in DCF fluorescence intensity after irradiation with laser radiation of 3 J, 10 J, and 20 J (CW, ƒ = 1000 Hz and ƒ = 2000 Hz) was also shown. Laser irradiation at a dose of 20 J, emitted at 1000 Hz and 2000 Hz, and 3 J emitted at a frequency of 2000 Hz caused a statistically significant loss of MSC viability. The applied photobiomodulation therapy induced a strong pro-apoptotic effect dependent on the laser irradiation exposure time, while the application of a sufficiently high-energy dose and frequency with a sufficiently long exposure time significantly increased intracellular calcium ion concentration and free radical production by MSCs.