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

Effectiveness of Laser Acupuncture for Reducing Pain and Increasing Mouth Opening Range in Individuals with Temporomandibular Disorder: A Systematic Review and Network Meta-Analysis

PURPOSE OF REVIEW

Laser acupuncture (LA) demonstrates promising results in the treatment of musculoskeletal disorders. However, its effects on temporomandibular disorder (TMD) are not yet fully understood. Thus, the aim of this systematic review and network meta-analysis was to assess the effectiveness of LA on pain intensity and maximum mouth opening range (MMO) related to TMD. A search was carried out in 11 electronic databases and references of included studies to locate randomized clinical trials (RCTs) that evaluated LA as a primary treatment for TMD. The risk of bias was assessed using the RoB 2 tool. Network meta-analysis was conducted on the MetaInsight platform, considering the pain intensity and counseling (C) as the outcome of reference. The GRADE system was used to assess the certainty of the evidence.

RECENT FINDINGS

Five studies evaluated pain intensity, four with a high risk of bias and one with a low risk. Two studies evaluated pain intensity on palpation (one with high and one with low risk of bias), and one study with high risk of bias evaluated MMO. Laser parameters were: 690-810 nm, 40-150 mW, and 7.5-112.5 J/cm2. Occlusal splint (OS) [- 2.47; CI 95% - 3.64, - 1.30] and Physiotherapy (PT) [-2.64; CI 95% - 3.94, - 1.34] reduced pain intensity compared to C. The ranking of treatments in order of effectiveness was PT > OS > LA > C > CR (craniopuncture). The certainty of the evidence was very low or low. The data do not support the indication of LA for the treatment of TMDs and new placebo-controlled RCTs must be conducted to demonstrate its effectiveness more precisely.

Photobiostimulation conjugated with stem cells or their secretome for temporomandibular joint arthritis in a rat model

BACKGROUND

Temporomandibular joint (TMJ) arthritis is a debilitating, challenging condition and different methods have been implicated for its treatment. This study aimed to test the therapeutic potentials of low-level laser therapy (LLLT) associated with adipose derived stem cells (ADSC) or their derived secretome on a murine model induced arthritis.

METHODS

Forty eight rats were divided into four groups where group I was the sham control, the rest of animals were subjected to arthritis induction using complete Freund's adjuvant, then divided as follows: group II received phosphate buffered saline (PBS) intraarticular injection and irradiation of 0 j/cm2, group III received ADSCs derived secretome and irradiation of 38 j/cm2, and group IV received ADSCs and irradiation of 38 j/cm2 as well. One and three weeks after treatment, animals were euthanized, and paraffin blocks were processed for histological assessment by hematoxylin and eosin stain with histomorphometrical analysis. Histochemical evaluation of joint proteoglycan content was performed through toluidine blue stain, and immunohistochemical staining by the proinflammatory marker tumor necrosis factor-α (TNF-α) was performed followed by the relevant statistical tests.

RESULTS

The arthritis group showed histological signs of joint injury including cartilage atrophy, articular disc fibrosis, irregular osteochondral interface, and condylar bone resorption together with high inflammatory reaction and defective proteoglycan content. In contrast, the treated groups III and IV showed much restoration of the joint structure with normal cartilage and disc thickness. The inflammation process was significantly suppressed especially after three weeks as confirmed by the significant reduction in TNF-α positive immunostaining compared to the arthritic group, and the cartilage proteoglycan content also showed significant increase relative to the arthritic group. However, no significant difference between the results of the two treated groups was detected.

CONCLUSION

LLLT conjugated with ADSCs or ADSCs derived secretome can efficiently enhance the healing of arthritic TMJs. Stem cell secretome can be applied as a safe, potent therapy. However, further investigations are required to unravel its mechanism of action and pave its way as a safe, novel, cell free therapy.

The Mechanisms and Efficacy of Photobiomodulation Therapy for Arthritis: A Comprehensive Review

Rheumatoid arthritis (RA) and osteoarthritis (OA) have a significant impact on the quality of life of patients around the world, causing significant pain and disability. Furthermore, the drugs used to treat these conditions frequently have side effects that add to the patient's burden. Photobiomodulation (PBM) has emerged as a promising treatment approach in recent years. PBM effectively reduces inflammation by utilizing near-infrared light emitted by lasers or LEDs. In contrast to photothermal effects, PBM causes a photobiological response in cells, which regulates their functional response to light and reduces inflammation. PBM's anti-inflammatory properties and beneficial effects in arthritis treatment have been reported in numerous studies, including animal experiments and clinical trials. PBM's effectiveness in arthritis treatment has been extensively researched in arthritis-specific cells. Despite the positive results of PBM treatment, questions about specific parameters such as wavelength, dose, power density, irradiation time, and treatment site remain. The goal of this comprehensive review is to systematically summarize the mechanisms of PBM in arthritis treatment, the development of animal arthritis models, and the anti-inflammatory and joint function recovery effects seen in these models. The review also goes over the evaluation methods used in clinical trials. Overall, this review provides valuable insights for researchers investigating PBM treatment for arthritis, providing important references for parameters, model techniques, and evaluation methods in future studies.

Effects of low-level laser therapy in adults with rheumatoid arthritis: A systematic review and meta-analysis of controlled trials

Rheumatoid arthritis (RA) is an inflammatory, systemic and chronic disease that mainly affects the joints. It is characterized mainly by pain, edema and joint stiffness, which can lead to significant loss of functional capacity and quality of life. Several physical therapy resources are used in the treatment of AR, such as low-level laser therapy (LLLT) and its analgesic and anti-inflammatory effects. However, the efficacy of LLLT in AR is still controversial. The objective of this study is to evaluate the efficacy of low-level laser therapy in adults with RA. Methods and findings: We searched MEDLINE, EMBASE, CENTRAL, PEDro, LILACS, IBECS, CUMED, SCIELO and ClinicalTrials.gov. Two researchers independently selected studies, extracted data, evaluated the risk of bias and assessed the certainty of evidence using GRADE approach. Disagreements were resolved by a third author. Meta-analyses were performed. Currently available evidence was from 18 RCTs, with a total of 793 participants. We found low-quality evidence suggesting there may be no difference between using infrared laser and sham in terms of pain, morning stiffness, grip strength, functional capacity, inflammation, ROM, disease activity and adverse events. The evidence is very uncertain about the effects of red laser compared to sham in pain, morning stiffness. The evidence is also very uncertain about the effects of laser acupuncture compared to placebo in functional capacity, quality of life, range of motion and inflammation. Conclusions: Thus, infrared laser may not be superior to sham in RA patients. There is insufficient information to support or refute the effectiveness of red laser, laser acupuncture and reflexology for treating patients with RA.

Suppression of matrix degradation and amelioration of disc degeneration by a 970-nm diode laser via inhibition of the p38 MAPK pathway in a rabbit model

Intervertebral disc degeneration (IVDD) mainly manifests as an imbalance between the synthesis and degradation of cellular and extracellular matrix (ECM) components. The cytokine interleukin (IL)-1β-induced inflammatory response of intervertebral discs causes ECM degradation. The aim of this study was to investigate the effects of a 970-nm diode laser therapy (DLT) on inflammatory cytokine IL-1β and ECM degradation proteinases in nucleus pulposus (NP) tissues in a puncture-induced rabbit IVDD model. Thirty-six New Zealand white rabbits were randomly divided into six groups: the normal group, IVDD group, laser group, sham laser group, IVDD + anisomycin (p38MAPK signaling pathway agonist), and laser + anisomycin group. Effects of laser on IVDD progression were detected using radiographic and magnetic resonance imaging. Hematoxylin and eosin, Alcian blue, safranin O-fast green staining, western blotting, and immunohistochemistry staining were performed for the histological analysis and molecular mechanism underlying protection against puncture-induced matrix degradation in NP tissues by DLT. DLT reduced the degree of disc degeneration in the gross anatomy of the disc and increased the T2-weighted signal intensity of NP. Inflammatory cytokine IL-1β levels in the disc were significantly reduced after DLT suppressed the matrix-degrading proteinases MMP13 and ADAMTS-5 and upregulated the protein expression of collagen II and aggrecan. Moreover, it inhibited the p38MAPK signaling pathway in NP tissues in a puncture-induced rabbit IVDD model. DLT reduced puncture-induced overexpression of inflammatory cytokines, mainly IL-1β, thus inhibiting matrix degeneration of NP tissues and ameliorating IVDD. This may be related to inhibition of the p38 MAPK signaling pathway.

Temporomandibular joint arthritis increases canonical Wnt pathway expression in the articular cartilage and trigeminal ganglion in rats

The canonical Wnt pathway participates in inflammatory diseases and it is involved in neuropathic pain. This study evaluated the immunoexpression of the canonical Wnt signaling pathway in the articular cartilage of the temporomandibular joint (TMJ) and along the nociceptive trigeminal pathway in arthritic rats. For this, male Wistar rats were divided into Control (C) and Arthritic (RA) groups. Arthritis induction was performed through subcutaneous injection of methylated bovine serum albumin (mBSA) and complete Freund Adjuvant (CFA)/ Incomplete Freund Adjuvant (IFA) on the first 14 days (once a week), followed by 3 weekly intra-articular injections of mBSA (10 μl/joint; left TMJ). The following parameters were evaluated: nociceptive threshold, inflammatory infiltrate, type I and III collagen birefringence, immunohistochemistry for IL-1β, TNF-α, IL-6, Wnt10b, β-catenin, cyclin-D1 in articular cartilage, c-Myc in synovial membrane, and immunofluorescence analysis for c-Fos, Wnt-10b and β-catenin in the trigeminal ganglion and the trigeminal subnucleus caudalis. The RA group showed intense articular cartilage damage with proliferation of type III collagen, increased immunoexpression of proinflammatory cytokines and Wnt-10b, β-catenin and cyclin-D1 in the articular cartilage and c-Myc in the synovial membrane. In the RA group, a reduction in the nociceptive threshold was observed, followed by a significant increase in the expression of Wnt-10b in neurons and β-catenin in satellite cells of the trigeminal ganglion. c-Fos immunoexpression was observed in neurons, peripherally and centrally, in arthritic rats. Our data demonstrated that TMJ arthritis in rats causes articular cartilage damage and nociceptive behavior, with increased immunoexpression of canonical Wnt pathway in the articular cartilage and trigeminal ganglion.

Application of photobiomodulation for chronic pain-related TMD on pain points versus pre-established points: Randomized clinical trial

Photobiomodulation therapy (PTB) is a therapeutic possibility for temporomandibular disorders (TMD), but its effectiveness and protocols for use remain controversial. This study is a RCT that compared the effectiveness of PTB on pain points of the masticatory muscles and TMJs, located through palpation versus application of pre-established points in women with painful TMD, diagnosis by DC/TMD (Diagnostic Criteria for Temporomandibular Disorders - Brazilian Portuguese version). Therefore, a total sample of 54 women, aged between 18 and 60 years, was investigated. Volunteers were randomly randomized and PTB was applied in four different groups with a dose of 4 J and 6 J divided into pre-established application points (PE - G1) and pain points (PD - G2) - Groups 4PE, 4PD, 6PE and 6PD. Four laser applications were performed with a wavelength of 780 nm, one session per week, totaling one month of therapy. The following assessments were performed: DC/TMD, Brief Pain Inventory (BPI), McGill Questionnaire - Short Version (SF-MPQ) and Pain Intensity, Visual Analogue Scale (VAS). Friedman's test was used for within-group comparisons, while the Mann-Whitney test was used for between-group comparisons (p < 0.05). According to the results, laser application on pain points (G2) was more effective. McGill's results showed that regardless of dose, the pain point application group had better outcomes (p = 0.004). Pain intensity evaluation (last days) also showed that application at the pain points was more effective regardless of dose (p = 0.0002). Medians and interquartile deviations showed overall that PTB was more effective at pain points, with a trend towards better outcomes at the 6 J dose. Therefore, it can be concluded that in women with chronic painful TMD, the application of PTB at pain points is more effective than the application at pre-established points. Therefore, individualized PTB protocols are proposed, based on examination palpation of the masticatory structures.

Regulation of interleukin-6 and matrix metalloproteinases syntheses by bioflavonoids and photobiomodulation in human gingival fibroblasts

This study aimed to evaluate the separately effects of bioflavonoids proanthocyanidins, from grape seed extract (GSE) and synthetic naringenin (NA), as well as photobiomodulation (PBM) by low-level laser therapy on interleukin (IL)-6 and matrix metalloproteinases (MMPs) syntheses by human gingival fibroblasts (HGF). For this purpose, a connective tissue exposure (ulceration) model of HGF, stimulated with tumor necrosis factor-alpha (TNF-α), was used. Initially, the highest non-cytotoxic and non-genotoxic concentrations of bioflavonoids were determined by cell viability and micronuclei formation assays. Then, HGF were exposed to different stimuli: culture medium (negative control), dimethyl sulfoxide (DMSO), TNF-α, NA, GSE, TNF-α + NA, TNF-α + GSE, PBM (3 J/cm², 0.025 W, 780 nm), and TNF-α + PBM. Next, IL-6, MMP-2, and MMP-9 syntheses were assessed. The concentration of 10 μg/mL of bioflavonoids increased cell viability at 24 and 48 h and did not present cytotoxic or genotoxic effects on HGF after 24, 48, and 72 h of contact. This concentration was selected for the assessment of bioflavonoids potential in modulating inflammatory mediators. TNF-α exposure enhanced IL-6 (170%), MMP-2 (10%), and MMP-9 (20%) syntheses, while a decrease of MMP-2 by 55% after exposure to TNF-α + GSE and 20% after TNF-α + NA and TNF-α + PBM was observed. MMP-9 synthesis was decreased by 35% after TNF-α + NA, 20% after TNF-α + GSE, and 30% after PBM. IL-6 was down-regulated by GSE in the presence of TNF-α (80%). In conclusion, TNF-α up-regulated IL-6 and MMPs, while bioflavonoids and PBM down-regulated MMP-2 and MMP-9 syntheses; GSE also decreased IL-6 synthesis, demonstrating the individual promising potential of these therapies for ulceration management.

Animal Models of Temporomandibular Joint Osteoarthritis: Classification and Selection

Temporomandibular joint osteoarthritis (TMJOA) is a common degenerative joint disease that can cause severe pain and dysfunction. It has a serious impact on the quality of lives of patients. Since mechanism underlying the pathogenesis of TMJOA is not fully understood, the development of effective tools for early diagnosis and disease-modifying therapies has been hindered. Animal models play a key role in understanding the pathological process of diseases and evaluating new therapeutic interventions. Although some similarities in disease processes between animals and humans are known, no one animal model is sufficient for studying all characteristics of TMJOA, as each model has different translatability to human clinical conditions. For the past 4 decades, TMJOA animal models have been studied by numerous researchers and can be broadly divided into induced, naturally occurring, and genetically modified models. The induced models can be divided into invasive models (intra-articular injection and surgical induction) or non-invasive models (mechanical loading, high-fat diet, and sleep deprivation). Different types of animal models simulate different pathological expressions of TMJOA and have their unique characteristics. Currently, mice, rats, and rabbits are commonly used in the study of TMJOA. This review sought to provide a general description of current experimental models of TMJOA and assist researchers in selecting the most appropriate models for different kinds of research.

Laser treatment of synovial inflammatory process in experimentally induced microcrystalline arthritis in Wistar rats

The presence of intra-articular crystals is detected in different articular pathologies of acute or chronic nature. The aim of this work was to analyze the action of the indium gallium aluminum and phosphorus (InGaAlP) (λ = 670 nm) laser on the synovial membrane present in the knee joint in experimentally induced microcrystalline arthritis in male adult Wistar rats. The animals were divided into three experimental groups (n = 24): control (A), experimentally induced arthritis (B), experimentally induced arthritis+InGaAlP laser therapy (C). The laser treatment was made daily in the patellar region of the right knee after 48 h of the experimental induction. After 7, 14, and 21 days of therapy, the rats were euthanized and the right knees were removed and processed for histomorphometric, immunohistochemical, ultrastructural, and biochemical investigation of the synovium. The number of granulocytes on the 14th and 21st days was higher in B and lower in C and, lastly, in A. The number of fibroblasts on the 14th and 21st days was similar between A and C and below B. The number of blood vessels on the 21st day was higher in B than in the other groups. The positive number of cells for the TUNEL test was higher on the 14th and 21st days in B compared to the others. The percentage of tissue area occupied by birefringent collagen fibers was higher in B on the 21st day than in the others. The ultrastructure of cells showed fibroblast-like morphology in all groups and periods evaluated. The quantification of glycosaminoglycans did not present significant differences between the groups in all the experimental periods. The amount of hydroxyproline was higher in B compared to the other groups on the 14th and 21st days. The content of non-collagen proteins was higher in B on the 21st day in relation to the other groups. Quantification of TNF-α on the 21st day was higher in A and B than in C. For TGF-β on the 21st day, groups B and C presented similar and higher values than A. For MMP-13, groups A and B presented data similar to and above C. In relation to ADAMT-S4, on the 21st day, groups B and C presented data similar to and lower than A. InGaAlP-670 nm therapy reduced the inflammatory process and tissue injuries of the synovial membrane in comparison to the untreated group, indicating its potential utilization in clinical studies aiming in the recovery of acute arthritis in patients.

Feprazone Ameliorates TNF-α-Induced Loss of Aggrecan via Inhibition of the SOX-4/ADAMTS-5 Signaling Pathway

Background: Arthritis is a cartilage degenerative disease that is mainly induced by the degradation of the cartilage extracellular matrix (ECM), which is found to be regulated by the expression level of a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMT-5), an enzyme degrading Aggrecans in the ECM. Feprazone is a classic nonsteroidal anti-inflammatory drug with promising efficacy in arthritis. The present study aims to investigate the protective effect of Feprazone on the degraded Aggrecan in the human chondrocytes induced with tumor necrosis factor-α (TNF-α) and to clarify the underlying mechanism. Methods: To investigate the effect of Feprazone, the CHON-001 chondrocytes were stimulated with TNF-α (10 ng/mL) in the presence or absence of Feprazone (3, 6 μM) for 24 h. Mitochondrial membrane potential was evaluated using the Rhodamine 123 assay. The gene expressions of interleukin-1β (IL-1β), interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and ADAMTS-5 in the treated chondrocytes were detected using real-time quantitative polymerase chain reaction (qRT-PCR), and the protein levels of these targets were determined using enzyme-linked immunosorbent assay (ELISA). SOX-4 was knocked down by transfecting the siRNA into the chondrocytes. Western blot analysis was utilized to evaluate the expression levels of SOX-4, Aggrecan, and protein kinase C (PKCα). Results: First, the reduced mitochondrial membrane potential (ΔΨ_m) and secretion of proinflammatory factors (IL-1β, IL-8, and MCP-1) induced by TNF-α were significantly reversed by treatment with Feprazone. Second, the expression of Aggrecan was significantly decreased by stimulation with TNF-α via upregulation of ADAMTS-5 but was dramatically reversed by the introduction of Feprazone. Third, we found that TNF-α elevated the expression of ADAMTS-5 by upregulating SOX-4, which was observed to be related to the activation of PKCα. Lastly, the elevated expression of SOX-4 induced by TNF-α was significantly reversed by Feprazone. Conclusions: Feprazone might ameliorate TNF-α-induced loss of Aggrecan via the inhibition of the SOX-4/ADAMTS-5 signaling pathway.

High-Frequency Near-Infrared Diode Laser Irradiation Attenuates IL-1β-Induced Expression of Inflammatory Cytokines and Matrix Metalloproteinases in Human Primary Chondrocytes

High-frequency near-infrared diode laser provides a high-peak output, low-heat accumulation, and efficient biostimulation. Although these characteristics are considered suitable for osteoarthritis (OA) treatment, the effect of high-frequency near-infrared diode laser irradiation in in vitro or in vivo OA models has not yet been reported. Therefore, we aimed to assess the biological effects of high-frequency near-infrared diode laser irradiation on IL-1β-induced chondrocyte inflammation in an in vitro OA model. Normal Human Articular Chondrocyte-Knee (NHAC-Kn) cells were stimulated with human recombinant IL-1β and irradiated with a high-frequency near-infrared diode laser (910 nm, 4 or 8 J/cm²). The mRNA and protein expression of relevant inflammation- and cartilage destruction-related proteins was analyzed. Interleukin (IL) -1β treatment significantly increased the mRNA levels of IL-1β, IL-6, tumor necrosis factor (TNF) -α, matrix metalloproteinases (MMP) -1, MMP-3, and MMP-13. High-frequency near-infrared diode laser irradiation significantly reduced the IL-1β-induced expression of IL-1β, IL-6, TNF-α, MMP-1, and MMP-3. Similarly, high-frequency near-infrared diode laser irradiation decreased the IL-1β-induced increase in protein expression and secreted levels of MMP-1 and MMP-3. These results highlight the therapeutic potential of high-frequency near-infrared diode laser irradiation in OA.

Photobiostimulation activity of different low-level laser dosage on masticatory muscles and temporomandibular joint in an induced arthritis rat model

This study aimed to investigate the anti-inflammatory effects of different dosage of low-level laser therapy (LLLT) in an experimental model of temporomandibular joint (TMJ) arthritis. One hundred male Wistar rats were used and divided into the following groups: CG, control group; AG, animals group with left TMJ arthritis induced by intra-articular injection of Complete Freund's adjuvant - CFA; LG5, LG10 and LG20 - animals with arthritis and treated with LLLT at doses 5, 10, and 20 J/cm², respectively. Morphological analysis was performed by TMJ histological sections stained with hematoxylin-eosin (HE), picrosirius (PSR), and toluidine blue (TB), as well as histomorphometric evaluation of cartilage, articular disc, and masticatory muscles. The amount of feed consumed within 3 weeks was evaluated, and biochemical analysis of TMJ tissues included measurement of sulfated glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) 2 and 9 zymography, and ELISA for cytokines IL-6, TNF-α, and IL-1β. Only the 20 J/cm² dose promoted higher feed intake compared to AG. On the other hand, all LLLT doses promoted better organization of articular disc collagen fibers, greater number of proteoglycans in articular cartilage, increased area and diameter of left lateral pterygoid fibers, reduced latent and active MMP 9 and 2 activity, and lower IL-1β concentration compared to AG. Considering the study limitations, it was observed that LLLT treatments were effective in protecting and tissue cleansing joint structures, accelerating tissue repair, especially at lower doses.

Effect of high molecular weight hyaluronic acid in treatment of osteoarthritic temporomandibular joints of rats

OBJECTIVE

The aim of this study was to determine the histological and biochemical effects of high molecular weight hyaluronic acid on experimentally induced osteoarthritic changes in male rat temporomandibular joint (TMJ).

DESIGN

In this in-vivo study, 36 male albino rats were divided into 3 groups; control non-injected, disease and treatment group. Osteoarthritis was induced using a single intra-articular injection of Complete Freund's adjuvant (CFA) (50 μl). High molecular weight hyaluronic acid (HMWHA) was injected intra-articularly once a week, for a total of 3 injections. TMJ tissue samples were dissected from control, disease and treatment groups for biochemical analysis using ELISA test to detect the levels of matrix metalloproteinase-3 (MMP-3) on day 28. Histological examination was done using Hematoxylin &eosin, Mallory's trichrome and Alcian blue stains. Data was analyzed using Kruskal-Wallis test followed by Dunn-Sidek method, with a 5 % significance level.

RESULTS

Treatment group showed regaining of the normal histological features of the TMJ and decreased levels of MMP-3 when compared to disease group.

CONCLUSIONS

These findings may suggest that HMWHA plays a role in the management of CFA-induced osteoarthritic cartilage lesions.

Evaluation of metalloproteinases-2, -9, and -13 post photobiomodulation in mice talocrural joint

The extracellular matrix (ECM) is the main constituent of connective tissue with structural and regulatory functions, stimulating cell differentiation and proliferation. Moreover, ECM is a dynamic structure in the constant remodeling process, which is controlled by a balance between metalloproteinases (MMPs) and their inhibitors (TIMPs). Photobiomodulation (PBM) is widely described in the literature and applied in clinical practices, although its effects on ECM have not yet been elucidated. Therefore, it was evaluated if PBM could alter ECM components, such as MMP-2, -9, -13, and TIMP-2 from mice talocrural joints. Mice were divided into 3 groups (n = 6): control, PBM 3 J cm^-2, and PBM 30 J cm^-2. A low-level laser (830 nm, 10 mW, 0.05 irradiated area, energy densities 3 J cm^-2 and 30 J cm^-2, the irradiation time of 15 and 150 s, respectively, continuous wave) was applied on the joint for 4 consecutive days. mRNA levels of metalloproteinases genes (MMP-2, MMP-9, and MMP-13), their regulator (TIMP-2), and protein expressions of MMP-13 and TIMP-2 were quantified. PBM can alter only mRNA relative levels of MMP-2 at 30 J cm^-2 (p < 0.05), while MMP-9, MMP-13, and TIMP-2 mRNA relative levels did not demonstrate statistical differences for any of the groups (p > 0.05). Regarding protein expressions, MMP-13 demonstrated positive-labeled cells, only in articular cartilage, although the cell quantification did not demonstrate statistical differences when compared with the control group (p > 0.05). TIMP-2 did not present positive-labeled cells for any tissues evaluated. Our results indicate that PBM can alter MMP-2 mRNA relative level but cannot alter MMP-9, MMP-13, and TIMP mRNA relative levels. Moreover, both MMP-13 and TIMP-2 proteins were also unaltered after PBM.

The effectiveness of photobiomodulation in the management of temporomandibular pain sensitivity in rats: behavioral and neurochemical effects

This study analyzed the effects of photobiomodulation (PBM) with low-level laser therapy on nociceptive behavior and neuronal activity in the trigeminal nucleus after experimental unilateral temporomandibular joint (TMJ) disc injury. The animals were divided into 4 groups (n = 10 each): group 1, surgical injury of the articular disc and PBM; group 2, sham-operated subjected to PBM; group 3, surgical injury of the articular disc; and group 4, control (Naïve). Ten sessions of PBM were performed using GaAs laser with a wavelength of 904 nm, power of 75 W pico, average power of 0.043 W, area of the beam of 0.13 cm², duration of the pulses of 60 nseg (in the frequency of 9500 Hz), energy density of 5.95 J/cm², energy per point of 0.7 J, and power density of 333.8 mW/cm², and the irradiation was done for 18 s per point. Neuropathic symptoms were evaluated using the von Frey test. Trigeminal ganglion samples underwent immunoblotting to examine the expression of substance P, vanilloid transient potential receptor of subtype-1 (TRPV-1), and peptide related to the calcitonin gene (CGRP). There was a total decrease in pain sensitivity after the second session of PBM in operated animals, and this decrease remains until the last session. There was a significant decrease in the expression of SP, TRPV-1, and CGRP after PBM. Photobiomodulation therapy was effective in reducing nociceptive behavior and trigeminal nucleus neuronal activity after TMJ disc injury.

Evaluation of the efficacy of a new low-level laser therapy home protocol in the treatment of temporomandibular joint disorder-related pain: A randomized, double-blind, placebo-controlled clinical trial

Objective: This study analyzed a home, low-level laser therapy (LLLT) protocol to manage temporomandibular joint disorders (TMJDs)-related pain.Methods: Ninety TMJD patients (12M, 78F) between 18 and 73 years were randomly subdivided into three groups. Study group (SG) received 1-week home protocol LLLT by B-cure Dental Pro: 808 nm, 5 J/min, 250 mW, 15 KHz for 8', 40 J each, over pain area, twice daily. Placebo group (PG) followed the same protocol using sham devices. Drugs group (DG) received conventional drugs. Pain was evaluated by visual analog scale (VAS) before and after therapy.Results: Statistical analysis showed that treatment was effective (F(2,83) = 4.882; p = .010). Bonferroni post-hoc analysis indicated a lower pain decrease in PG. SG registered a 34-point decrease per patient, while in PG and DG, the reduction was 25.6 and 35.3, respectively.Conclusion: The study supports the efficacy of home LLLT management of TMJD related pain.

Effects of low-level laser therapy on the organization of articular cartilage in an experimental microcrystalline arthritis model

The aim of this study was to evaluate the effects of low-level laser therapy using the gallium arsenide laser (λ = 830 nm) on the articular cartilage (AC) organization from knee joint in an experimental model of microcrystalline arthritis in adult male Wistar rats. Seventy-two animals were divided into three groups: A (control), B (induced arthritis), and C (induced arthritis + laser therapy). The arthritis was induced in the right knee using 2 mg of Na₄P₂O₇ in 0.5 mL of saline solution. The treatments were daily applied in the patellar region of the right knee after 48 h of induction. On the 7th, 14th, and 21st days of treatment, the animals were euthanized and their right knees were removed and processed for structural and biochemical analysis of the AC. The chondrocytes positively labeled for the TUNEL reaction were lower in C than in B on the 14th and 21st days. The content of glycosaminoglycans and hydroxyproline in A and C was higher than B on the 21st day. The amount of tibial TNF-α in B and C was lower than in A. The amount of tibial BMP-7 in B and C was higher than in A. The femoral MMP-13 was lower in B and C than for A. The tibial TGF-β for C was higher than the others. The femoral ADAMT-S4 content of A and C presented similar and inferior data to B on the 21st day. The AsGa-830 nm therapy preserved the content of glycosaminoglycans, reduced the cellular changes and the inflammatory process compared to the untreated group.

Temporomandibular joint arthritis in juvenile idiopathic arthritis, now what?

BACKGROUND

Arthritis involving the temporomandibular joint (TMJ) complicates 40 - 96% of cases of juvenile idiopathic arthritis (JIA), potentially leading to devastating changes to form and function. Optimal evaluation and management of this joint remains a matter of ongoing discussion.

METHODS

We performed a PubMed search for all articles with keywords "temporomandibular" and "arthritis", covering the dates 2002 through February 28, 2018. A separate PubMed search was performed for all articles with keywords "temporomandibular joint", "arthritis", and "treatment" covering the same dates.

FINDINGS

The TMJ is a particularly challenging joint to assess, both clinically and with imaging studies. Clinical assessment of the TMJ is hampered by the low sensitivity of joint pain as well as the absence of physical exam findings early in the disease process. As with all joints, plain radiography and computed tomography only detect arthritic sequelae. Additionally, there is mixed data on the sensitivity of ultrasound, leaving magnetic resonance imaging (MRI) as the optimal diagnostic modality. However, several recent studies have shown that non-arthritic children can have subtle findings on MRI consistent with TMJ arthritis, such as joint effusion and contrast enhancement. Consequently, there has been an intense effort to identify features that can be used to differentiate mild TMJ arthritis from normal TMJs, such as the ratio of the enhancement within the TMJ itself compared to the enhancement in surrounding musculature. With respect to treatment of TMJ arthritis, there is minimal prospective data on medical therapy of this complicated joint. Retrospective studies have suggested that the response to medical therapy of the TMJ may lag behind that of other joints, prompting use of intraarticular (IA) therapy. Although most studies have shown short-term effectiveness of corticosteroids, the long-term safety of this therapy on local growth as well as on the development of IA heterotopic bone have prompted recommendations to limit use of IA corticosteroids. Severe TMJ disease from JIA can also be managed non-operatively with splints in a growing child, as well as with surgery.

CONCLUSION

In this review, we summarize literature on the diagnosis and management of TMJ arthritis in JIA and suggest a diagnostic and therapeutic algorithm for children with refractory TMJ arthritis.

Could adverse effects and complications of selective laser trabeculoplasty be decreased by low-power laser therapy?

Selective laser trabeculoplasty (SLT) has been used for treatment of primary open-angle glaucoma, ocular hypertension, pigmenter and pseudoexfoliative glaucoma being considered a low-risk procedure. Therefore, transitory and permanent adverse effects have been reported, including corneal changes, subclinical edema, and reduction in endothelial cells and in central corneal thickness. Despite rarer, serious corneal complications after SLT can be permanent and lead to visual impairment, central corneal haze, opacity and narrowing. The mechanism involves increase of vasoactive and chemotactic cytokines causing inflammatory infiltrate, destruction of stromal collagen by fibroblasts and increase of matrix metalloproteinases type 2, which impair reepithelization. SLT also increases free radical production and reduces antioxidant enzymes, resulting in endothelium damages. Low-power laser therapy (LPLT) has been used in regenerative medicine based on its biostimulatory and anti-inflammatory effects. Biostimulation occurs through the interaction of laser photons with cytochrome C oxidase enzyme, which activates intracellular biochemical cascades causing synthesis of a number of molecules related to anti-inflammatory, regenerative effects, pain relief and reduction in edema. It has been showed that LPLT reduces gene expression related to pro-inflammatory cytokines and matrix metalloproteinases, and it increases expression of growth factors related to its proliferative and healing actions. Although radiations emitted by low-power lasers are considered safe and able to induce therapeutic effects, researches based on experimental models for glaucoma could bring important data if LPLT could be an alternative approach to improve acceptation for patients undergoing SLT.

Low-intensity laser therapy efficacy evaluation in FVB mice subjected to acute and chronic arthritis

Rheumatoid arthritis, an autoimmune inflammation, has a high prevalence in the population, and while therapy is available, it required often injection of drugs causing discomfort to patients. This study evaluates the clinical and histological effect of low-intensity laser therapy (LILT) as an alternative treatment, in a murine model of acute and chronic inflammation. FVB mice received either a Zymosan A injection into one knee joint inducing acute inflammation, followed after 15 min or 24 h by LILT or a collagen bovine type II injection emulsified in "Freund's Complete Adjuvant" to induce chronic arthritis, followed at 4 weeks with multiple LILT sessions. LILT mediated by either 660, 808, or 905 nm and tissue response was evaluated based on clinical symptoms and histological analysis of inflammatory infiltrate and damage to the articular surfaces. LILT can be effective in elevating clinical symptoms, so Kruskal-Wallis testing indicated no significant differences between knees affected by acute arthritis and treated once with LILT and an injured knee without treatment (p > 0.05) for 660 and 808 nm with some improvements for the 905-nm LILT. Mice receiving two treatments for acute arthritis showed exacerbation of inflammation and articular resorption following therapy with a 660-nm continuous laser (p < 0.05). For chronic inflammation, differences were not noted between LILT treated and untreated injured knee joints (p > 0.05). Among the lasers, the 905 nm tends to show better results for anti-inflammatory effect in acute arthritis, and the 660 nm showed better results in chronic arthritis. In conclusion, LILT wavelength selection depends on the arthritis condition and can demonstrate anti-inflammatory effects for chronic arthritis and reduced resorption area in this murine model.