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-ß 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.

Biophysical stimulation of bone and cartilage: state of the art and future perspectives.

INTRODUCTION: Biophysical stimulation is a non-invasive therapy used in orthopaedic practice to increase and enhance reparative and anabolic activities of tissue. METHODS: A sistematic web-based search for papers was conducted using the following titles: (1) pulsed electromagnetic field (PEMF), capacitively coupled electrical field (CCEF), low intensity pulsed ultrasound system (LIPUS) and biophysical stimulation; (2) bone cells, bone tissue, fracture, non-union, prosthesis and vertebral fracture; and (3) chondrocyte, synoviocytes, joint chondroprotection, arthroscopy and knee arthroplasty. RESULTS: Pre-clinical studies have shown that the site of interaction of biophysical stimuli is the cell membrane. Its effect on bone tissue is to increase proliferation, synthesis and release of growth factors. On articular cells, it creates a strong A2A and A3 adenosine-agonist effect inducing an anti-inflammatory and chondroprotective result. In treated animals, it has been shown that the mineralisation rate of newly formed bone is almost doubled, the progression of the osteoarthritic cartilage degeneration is inhibited and quality of cartilage is preserved. Biophysical stimulation has been used in the clinical setting to promote the healing of fractures and non-unions. It has been successfully used on joint pathologies for its beneficial effect on improving function in early OA and after knee surgery to limit the inflammation of periarticular tissues. DISCUSSION: The pooled result of the studies in this review revealed the efficacy of biophysical stimulation for bone healing and joint chondroprotection based on proven methodological quality. CONCLUSION: The orthopaedic community has played a central role in the development and understanding of the importance of the physical stimuli. Biophysical stimulation requires care and precision in use if it is to ensure the success expected of it by physicians and patients.

Short term histopathological effects of GaAlAs laser on experimentally induced TMJ osteoarthritis in rabbits.

The aim of this study was to evaluate the biostimulation (BS) effect of the gallium-aluminum-arsenide (GaAlAs) diode laser by histopathology with an experimental osteoarthritis (OA) model in the temporomandibular joints (TMJ) of rabbits, in the early period. GaAlAs diode laser is used for pain reduction in TMJ disorders. Twenty-four adult male New Zealand white rabbits were randomly divided into three equal groups: Control Group (CG), Study Group 1 (SG-1), and Study Group 2 (SG-2). Mono-iodoacetate (MIA) was administered to the right TMJs of all rabbits. The rabbits did not undergo any treatment for four weeks to allow the development of osteoarthritis. In SG-1, laser BS was applied to the rabbits at 940 nm, 5 W, and 15 J/cm2 in continuous wave mode at 48-hour intervals for 14 sessions; and in SG-2, laser BS was applied with the same parameters at 24-hour intervals for 28 sessions. Laser BS was not applied to the rabbits in CG. All rabbits were sacrificed simultaneously. The TMJ cartilage, osteochondral junction, chondrocyte appearance, and subchondral ossification were evaluated histopathologically. There was no statistically significant difference between the groups in terms of cartilage, osteochondral junction, chondrocyte appearance, and subchondral ossification values (p > 0.05). The laser BS protocol used in the study had no positive histopathological effects on TMJ OA in the early period.

Chondroitin sulfate and glucosamine sulfate associated to photobiomodulation prevents degenerative morphological changes in an experimental model of osteoarthritis in rats.

The aim of this study was to compare the effects of combined treatment with chondroitin sulfate and glucosamine sulfate (CS/Gl) and photobiomodulation (PBM) on the degenerative process related to osteoarthritis (OA) in the articular cartilage in rats. Forty male Wistar rats were randomly divided into four groups: OA control group (CG); OA animals submitted to PBM treatment (PBM); OA animals submitted to CS/Gl treatment (CS/Gl); OA submitted to CS/GS associated with PBM treatments (GS/Gl + PBM). The CS/Gl started 48 h after the surgery, and they were performed for 29 consecutive days. Moreover, PBM was performed after the CS/Gl administration on the left joint. Morphological characteristics and immunoexpression of interleukin 10 (IL-10) and 1 beta (IL-1ß) and collagen type II (Col II) of the articular cartilage were evaluated. The results showed that all treated groups (CS/Gl and PBM) presented attenuation signs of degenerative process (measured by histopathological analysis) and lower density chondrocytes [PBM (p = 0.0017); CS/Gl (p = 0.0153) and CS/Gl + PBM (p = 0.002)]. Additionally, CS/Gl [associated (p = 0.0089) or not with PBM (p = 0.0059)] showed significative lower values for OARSI grade evaluation. Furthermore, CS/GS + PBM decreased IL-1ß protein expression (p = 0.0359) and increased IL-10 (p = 0.028) and Col II imunoexpression (p = 0.0204) compared to CG. This study showed that CS/Gl associated with PBM was effective in modulating inflammatory process and preventing the articular tissue degradation in the knees OA rats.

Short term histopathological effects of GaAlAs laser on experimentally induced TMJ osteoarthritis in rabbits

Abstract The aim of this study was to evaluate the biostimulation (BS) effect of the gallium-aluminum-arsenide (GaAlAs) diode laser by histopathology with an experimental osteoarthritis (OA) model in the temporomandibular joints (TMJ) of rabbits, in the early period. GaAlAs diode laser is used for pain reduction in TMJ disorders. Twenty-four adult male New Zealand white rabbits were randomly divided into three equal groups: Control Group (CG), Study Group 1 (SG-1), and Study Group 2 (SG-2). Mono-iodoacetate (MIA) was administered to the right TMJs of all rabbits. The rabbits did not undergo any treatment for four weeks to allow the development of osteoarthritis. In SG-1, laser BS was applied to the rabbits at 940 nm, 5 W, and 15 J/cm2 in continuous wave mode at 48-hour intervals for 14 sessions; and in SG-2, laser BS was applied with the same parameters at 24-hour intervals for 28 sessions. Laser BS was not applied to the rabbits in CG. All rabbits were sacrificed simultaneously. The TMJ cartilage, osteochondral junction, chondrocyte appearance, and subchondral ossification were evaluated histopathologically. There was no statistically significant difference between the groups in terms of cartilage, osteochondral junction, chondrocyte appearance, and subchondral ossification values (p > 0.05). The laser BS protocol used in the study had no positive histopathological effects on TMJ OA in the early period.

Effects of microcurrent therapy on excisional elastic cartilage defects in young rats.

The effects of microcurrent application on the elastic cartilage defects in the outer ear of young animals were analyzed. Sixty male Wistar rats were divided into a control (CG) and a treated group (TG). An excisional lesion was created in the right outer ear of each animal. Daily treatment was started after 24h and consisted of the application of a low-intensity (20µA) continuous electrical current to the site of injury for 5min. The animals were euthanized after 7, 14 and 28 days of injury and the samples were submitted to analyses. In CG, areas of newly formed cartilage and intense basophilia were seen at 28 days, while in TG the same observations were made already at 14 days. The percentage of birefringent collagen fibers was higher in CG at 28 days. The number of connective tissue cells and granulocytes was significantly higher in TG. Ultrastructural analysis revealed the presence of chondrocytes in TG at 14 days, while these cells were observed in CG only at 28 days. Cuprolinic blue staining and the amount of glycosaminoglycans were significantly higher in TG at 14 days and 28 days. The amount of hydroxyproline was significantly higher in TG at all time points studied. The active isoform of MMP-2 was higher activity in TG at 14 days. Immunoblotting for type II collagen and decorin was positive in both groups and at all time points. The treatment stimulated the proliferation and differentiation of connective tissue cells, the deposition of glycosaminoglycans and collagen, and the structural reorganization of these elements during elastic cartilage repair.

Resurfacing damaged articular cartilage to restore compressive properties.

Surface damage to articular cartilage is recognized as the initial underlying process causing the loss of mechanical function in early-stage osteoarthritis. In this study, we developed structure-modifying treatments to potentially prevent, stabilize or reverse the loss in mechanical function. Various polymers (chondroitin sulfate, carboxymethylcellulose, sodium hyaluronate) and photoinitiators (riboflavin, irgacure 2959) were applied to the surface of collagenase-degraded cartilage and crosslinked in situ using UV light irradiation. While matrix permeability and deformation significantly increased following collagenase-induced degradation of the superficial zone, resurfacing using tyramine-substituted sodium hyaluronate and riboflavin decreased both values to a level comparable to that of intact cartilage. Repetitive loading of resurfaced cartilage showed minimal variation in the mechanical response over a 7 day period. Cartilage resurfaced using a low concentration of riboflavin had viable cells in all zones while a higher concentration resulted in a thin layer of cell death in the uppermost superficial zone. Our approach to repair surface damage initiates a new therapeutic advance in the treatment of injured articular cartilage with potential benefits that include enhanced mechanical properties, reduced susceptibility to enzymatic degradation and reduced adhesion of macrophages.

The effect of light-emitting diode and laser on mandibular growth in rats.

OBJECTIVE: To evaluate the effect of a light-emitting diode (LED) and/or low-level laser (LLL) with or without the use of anterior bite jumping appliances (also known as functional appliances [FAs]) on mandibular growth in rats. MATERIALS AND METHODS: Thirty-six 8-week-old male Sprague-Dawley rats weighing 200 g were obtained from Charles River Canada (St. Constant, QC, Canada) and were divided into six groups of six animals each. Groups were as follows: group 1: LLL; group 2: LLL + FA; group 3: LED; group 4: LED + FA; group 5: FA; and group 6: control (no treatment). Mandibular growth was evaluated by histomorphometric and micro computed tomographic (microCT) analyses. RESULTS: The LED and LED + FA groups showed an increase in all condylar tissue parameters compared with other groups. CONCLUSION: The LED-treated groups showed more mandibular growth stimulation compared with the laser groups.

Therapeutic effect of irradiation of magnetic infrared laser on osteoarthritis rat model.

Osteoarthritis (OA) is a degenerative joint disease caused by articular cartilage loss. Many complementary and alternative medicines for OA have been reported so far, but the effectiveness is controversial. Previously, we have shown anti-inflammatory effects of low level laser therapy with static magnetic field, magnetic infrared laser (MIL), in various animal models. Therefore, the beneficial effects were examined in OA rat model. Rats were divided by six groups; no treatment controls of sham and OA model, three MIL treatment groups of OA model at 6.65, 2.66 and 1.33 J cm(-2), and Diclofenac group of OA model with 2 mg kg(-1) diclofenac sodium. The OA control exhibited typical symptoms of OA, but 4-week MIL treatment improved the functional movement of knee joint with reduced edematous changes. In addition, cartilage GAGs were detected more in all MIL treatment groups than OA control. It suggests that 4-week MIL irradiation has dose-dependent anti-inflammatory and chondroprotective effects on OA. Histopathological analyses revealed that MIL treatment inhibits the cartilage degradation and enhances chondrocyte proliferation. The fact that MIL has an additional potential for the cartilage formation and no adverse effects can be regarded as great advantages for OA treatment. These suggest that MIL can be useful for OA treatment.

Effects of low-level laser therapy on joint pain, synovitis, anabolic, and catabolic factors in a progressive osteoarthritis rabbit model.

The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on short-term and long-term joint pain, synovitis, anabolic, and catabolic factors in the cartilage of a rabbit model with progressive osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT). A total of 160 New Zealand white rabbits were randomly assigned into two groups (ACLT group and LLLT group). All rabbits received ACLT surgery, and 2-, 4-, 6-, and 8-week treatment after the surgery, with 20 rabbits being tested biweekly over every study period. The LLLT group received LLLT with a helium-neon (He-Ne) laser (830 nm) of 1.5 J/cm(2) three times per week, and the ACLT group received placebo LLLT with the equipment switched off. Long-term and short-term pain was tested via weight-bearing asymmetry; synovitis was assessed histologically; and knee joint cartilage was evaluated by gross morphology, histology, and gene expression analysis of anabolic and catabolic factors. The histological assessment of pain and synovitis showed that at least 6-week intermittent irradiation of LLLT could relief knee pain and control synovium inflammation. Gross morphologic inspection and histological evaluation showed that 6 weeks of LLLT could decrease cartilage damage of medical femoral condyle and 8 weeks of LLLT could decrease cartilage damage of medical and lateral femoral condyles and medical tibial plateau. Gene expression analysis revealed two results: At least 6 weeks of LLLT could decrease production of catabolic factors, for example, interleukin 1ß (IL-1ß), inducible nitric oxide synthase (iNOS), and MMP-3, and slow down the loss of anabolic factors, mainly TIMP-1. Eight weeks of LLLT treatment could slow down the loss of collagen II, aggrecan, and anabolic factors, mainly transforming growth factor beta (TGF-ß). The study suggests that LLLT plays a protective role against cartilage degradation and synovitis in rabbits with progressive OA by virtue of the regulation of catabolic and anabolic factors in the cartilage.

Proteomics of human primary osteoarthritic chondrocytes exposed to extremely low-frequency electromagnetic fields (ELF EMFs) and to therapeutic application of musically modulated electromagnetic fields (TAMMEF).

Osteoarthritis (OA) is the most frequent joint disease, characterized by degradation of extracellular matrix and alterations in chondrocyte metabolism. Some authors reported that electromagnetic fields (EMFs) can positively interfere with patients affected by OA, even though the nature of the interaction is still debated. Human primary osteoarthritic chondrocytes isolated from the femoral heads of OA-patients undergoing to total hip replacement, were cultured in vitro and exposed 30 min/day for two weeks to extremely-low-frequency electromagnetic field (ELF) with fixed frequency (100 Hz) and to therapeutic application of musically modulated electromagnetic fields (TAMMEF) with variable frequencies, intensities and waveforms. Sham-exposed (S.E.) cells served as control group. Cell viability was measured at days 2, 7 and 14. After two weeks, cell lysates were processed using a proteomic approach. Chondrocyte exposed to ELF and TAMMEF system demonstrated different viability compared to untreated chondrocytes (S.E.). Proteome analysis of 2D-Electrophoresis and protein identification by mass spectrometry showed different expression of proteins derived from nucleus, cytoplasm and organelles. Function analysis of the identified proteins showed changes in related-proteins metabolism (glyceraldeyde-3-phosphate-dehydrogenase), stress response (Mn-superoxide-dismutase, heat-shock proteins), cytoskeletal regulation (actin), proteinase inhibition (cystatin-B) and inflammation regulatory functions (S100-A10, S100-A11) among the experimental groups (ELF, TAMMEF and S.E.). In conclusion, EMFs do not cause damage to chondrocytes, besides stimulate safely OA-chondrocytes and are responsible of different protein expression among the three groups. Furthermore, protein analysis of OA-chondrocytes treated with ELF and the new TAMMEF systems could be useful to clarify the pathogenetic mechanisms of OA by identifying biomarkers of the disease.

Effect of pulsed electromagnetic fields on the bioactivity of human osteoarthritic chondrocytes.

Low-frequency pulsed electromagnetic fields (PEMFs) are used for the treatment of human osteoarthritic cells in vivo without knowledge of underling principles. The authors evaluated the effect of PEMFs on human chondrocytes of the osteoarthritic knee in vitro. Biopsies of the cut femoral condyles after total knee arthroplasty were kept in a standard cell culture medium consisting of Dulbecco's modified Eagle's medium: nutrient mixture F-12, 10% fetal calf serum, PenStrept (Mediatech, Inc, Manassas, Virginia), and ascorbic acid for 4 days and randomly split into an exposed group (PEMF for 4 hours daily for 4 days at 75 Hz and 1.6 mT) and a control group. Both groups were retained for biochemical and polymerase chain reaction analysis (glycosaminoglycan and DNA levels). A P value less than .05 was considered significant.DNA analysis revealed no differences between groups and no increase in content after exposure (P=.88 and .66, respectively). The increase of glycosaminoglycans was 0.4±1.6 ng (95% confidence interval [CI], 1.4 to 0.5) and -0.5±1.8 ng (95% CI, 0.6 to -1.5) in the exposed and control groups, respectively, with no significant difference (P=.24). A smaller decrease of glycosaminoglycan and DNA levels was observed over 4 days in the exposed group compared with the control group, with no statistical significance. The authors concluded that low-frequency PEMFs do not significantly influence the biosynthetic activity of explantcultures of human osteoarthritic cells in vitro. Nevertheless, they may be suitable as an adjuvant to a larger treatment regimen.

Low-level laser therapy in different stages of rheumatoid arthritis: a histological study.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease of unknown etiology. Treatment of RA is very complex, and in the past years, some studies have investigated the use of low-level laser therapy (LLLT) in treatment of RA. However, it remains unknown if LLLT can modulate early and late stages of RA. With this perspective in mind, we evaluated histological aspects of LLLT effects in different RA progression stages in the knee. It was performed a collagen-induced RA model, and 20 male Wistar rats were divided into 4 experimental groups: a non-injured and non-treated control group, a RA non-treated group, a group treated with LLLT (780 nm, 22 mW, 0.10 W/cm(2), spot area of 0.214 cm(2), 7.7 J/cm(2), 75 s, 1.65 J per point, continuous mode) from 12th hour after collagen-induced RA, and a group treated with LLLT from 7th day after RA induction with same LLLT parameters. LLLT treatments were performed once per day. All animals were sacrificed at the 14th day from RA induction and articular tissue was collected in order to perform histological analyses related to inflammatory process. We observed that LLLT both at early and late RA progression stages significantly improved mononuclear inflammatory cells, exudate protein, medullary hemorrhage, hyperemia, necrosis, distribution of fibrocartilage, and chondroblasts and osteoblasts compared to RA group (p < 0.05). We can conclude that LLLT is able to modulate inflammatory response both in early as well as in late progression stages of RA.

Human osteoarthritic chondrocytes exposed to extremely low-frequency electromagnetic fields (ELF) and therapeutic application of musically modulated electromagnetic fields (TAMMEF) systems: a comparative study.

Osteoarthritis (OA) is the most common joint disease, characterized by matrix degradation and changes in chondrocyte morphology and metabolism. Literature reported that electromagnetic fields (EMFs) can produce benefits in OA patients, even if EMFs mechanism of action is debated. Human osteoarthritic chondrocytes isolated from femoral heads were cultured in vitro in bidimensional (2-D) flasks and in three-dimensional (3-D) alginate beads to mimic closely cartilage environment in vivo. Cells were exposed 30 min/day for 2 weeks to extremely low-frequency electromagnetic field (ELF) with fixed frequency (100 Hz) and to therapeutic application of musically modulated electromagnetic field (TAMMEF) with variable frequencies, intensities, and waveforms. Cell viability was measured at days 7 and 14, while healthy-cell density, heavily vacuolized (hv) cell density, and cluster density were measured by light microscopy only for 3-D cultures after treatments. Cell morphology was observed for 2-D and 3-D cultures by transmission electron microscopy (TEM). Chondrocyte exposure to TAMMEF enhances cell viability at days 7 and 14 compared to ELF. Light microscopy analysis showed that TAMMEF enhances healthy-cell density, reduces hv-cell density and clustering, compared to ELF. Furthermore, TEM analysis showed different morphology for 2-D (fibroblast-like) and 3-D (rounded shape) cultures, confirming light microscopy results. In conclusion, EMFs are effective and safe for OA chondrocytes. TAMMEF can positively interfere with OA chondrocytes representing an innovative non-pharmacological approach to treat OA.

Low-level laser on femoral growth plate in rats.

PURPOSE: To determine the influence of low-level laser therapy on femoral growth plate in rats. METHODS: Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm(2). The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. RESULTS: In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. CONCLUSION: The low-level laser therapy negatively influenced the distal femoral growth plate.

Low-level laser on femoral growth plate in rats / Laser terapêutico de baixa potência na placa de crescimento de ratos

PURPOSE: To determine the influence of low-level laser therapy on femoral growth plate in rats. METHODS: Thirty male Wistar rats aged 40 days were divided into two groups, G1 and G2. In G1 the area of the distal growth plate of the right femur was irradiated at one point using GaAlAs laser 830 nm wavelength, output power of 40 mW, at an energy density of 10 J/cm². The irradiation was performed daily for a maximum of 21 days. The same procedure was done in G2, but the probe was turned off. Five animals in each group were euthanized on days 7, 14 and 21 and submitted to histomorphometric analysis. RESULTS: In both groups the growth plate was radiographically visible at all moments from both craniocaudal and mediolateral views. On the 21st day percentage of femoral longitudinal length was higher in G2 than G1 compared to basal value while hypertrophic zone chondrocyte numbers were higher in G1 than G2. Calcified cartilage zone was greater in G1 than in G2 at all evaluation moments. Angiogenesis was higher in G1 than in G2 at 14th and 21st days. CONCLUSION: The low-level laser therapy negatively influenced the distal femoral growth plate.

OBJETIVO: Determinar a influência do Laser Terapêutico de Baixa Potência sobre a placa de crescimento de ratos. MÉTODOS: Trinta ratos Wistar machos com 40 dias de idade foram divididos em dois grupos, G1 e G2. O grupo G1 foi submetido à irradiação com laser GaAlAs 830 nm, potência de saída de 40 mW, e densidade de energia de 10 J/cm2. A irradiação foi aplicada diariamente por um período máximo de 21 dias. O mesmo procedimento foi realizado no grupo G2, com a probe desativada. Cinco animais em cada grupo foram sacrificados nos dias 7, 14 e 21 e submetidas à análise histomorfométrica. RESULTADOS: Em ambos os grupos, o disco fisário esteve radiograficamente visível em todos os momentos nas incidências craniocaudal e médio-lateral. No 21º dia a porcentagem de comprimento longitudinal do fêmur foi maior em G1 que em G2 em relação ao valor basal, e o número de condrócitos da zona hipertrófica foi maior em G1 que em G2. A zona de cartilagem calcificada estava maior em G1 em relação a G2 em todos os momentos de avaliação. A angiogênese foi maior em G1 que em G2 nos 14º e 21º dias. CONCLUSÃO: A terapia com laser terapêutico de baixa potência influenciou negativamente o disco fisário distal do fêmur de ratos.

The effect of 904 nm low level laser on condylar growth in rats.

A growth center of the mandible that contributes to its length and height is the mandibular condyle. Proliferation of prechondroblasts, followed by synthesis of the extracellular matrix and hypertrophy of the cartilage cells, governs the major part of condylar growth. The sample consisted of 54 male rats, weighing between 60 g and 80 g, divided randomly into three groups. Group I was the control group, group II was irradiated bilaterally, and group III was irradiated on the right side. Laser irradiation (lambda = 904 nm, 2000 Hz, pulse length 200 ns and output power 4 mW) was performed, and the procedure was repeated after a 50-day interval. Two months later, the rats were killed. In a single blind manner the lengths of denuded mandibles and the lengths of mandibles on soft tissue were measured. The growth of the mandibles in the unilaterally irradiated group (P < 0.001) and the bilaterally irradiated group (P < 0.05) was significantly more than that in the control group. There was no significant difference between right and left condylar growth in the bilaterally irradiated group (P = 0.3). Soft tissue analysis also verified these results (P < 0.001). Histomorphometric results also revealed a significant difference between laser-irradiated groups and the control group (P < 0.01). We concluded that particular laser irradiation with the chosen parameters can stimulate condylar growth and subsequently cause mandibular advancement. These findings might be clinically relevant, indicating that low level laser irradiation can be used for further improvement of mandibular retrognathism.

The effects of laser irradiation of cartilage on chondrocyte gene expression and the collagen matrix.

OBJECTIVES: Laser reshaping of cartilage is an emerging technology aimed at replacing conventional techniques for aesthetic and reconstructive surgery. Little is known about the mechanisms of wound healing following the photothermal heating during laser reshaping and, ultimately, how collagen remodels in the irradiated tissue. Healthy hyaline and elastic cartilage as found in the ear, nose, larynx, and trachea does not express collagen type I which is characteristic of fibro-cartilage and scar tissue. The aim of the study was to determine if collagen I and II gene expression occurs within laser irradiated rabbit septal cartilage. METHODS: Nasal septum harvested from freshly euthanized New Zealand White rabbits were irradiated with an Nd:YAG laser. After 2 weeks in culture, the laser spot and surrounding non-irradiated regions were imaged using immunofluorescence staining and evaluated using reverse transcription polymerase chain reaction (RT-PCR) to determine the presence of collagen I and II, and ascertain collagen I and II gene expression, respectively. RESULTS: All laser irradiated specimens showed a cessation in collagen II gene expression within the center of the laser spot. Collagen II was expressed in the surrounding region encircling the laser spot and within the non-irradiated periphery in all specimens. Immunohistochemistry identified only type II collagen. Neither collagen I gene expression nor immunoreactivity were identified in any specimens regardless or irradiation parameters. CONCLUSIONS: Laser irradiation of rabbit septal cartilage using dosimetry parameters similar to those used in laser reshaping does not result in the detection of either collagen I gene expression or immunoreactivity. Only collagen type II was noted after laser exposure in vitro following cell culture, which suggests that the cellular response to laser irradiation is distinct from that observed in conventional wound healing. Laser irradiation of cartilage can leave an intact collagen matrix which likely allows chondrocyte recovery on an intact scaffold.

The histological and clinical effects of 630 nanometer and 860 nanometer low-level laser on rabbits' ear punch holes.

Low-level laser therapy (LLLT) studies on the musculoskeletal and cartilage tissues of rabbits have reported conflicting results. We aimed to investigate the effects of 630 nm and 860 nm low-level laser on injured rabbit cartilage. After punching 5 mm holes in both ears of ten rabbits, we grouped the rabbits randomly. The punched holes of the laser-treated group were irradiated with 630 nm and 860 nm diode laser on days 3-5 and then every other day until day 20. In both laser and control groups, the hole diameters were measured weekly. Histological evaluation was carried out on day 30. The inter-group difference in hole diameters was not significant. Mann-Whitney U tests showed significant inter-group differences in histological variables related to chondrocyte production and organization, growth rate, granulation tissue and pseudocarcinomatosis. LLLT improved cartilage formation and reduced inflammation and formation of granulation tissue. More accurate results on its healing effects warrant studies with larger sample sizes.

Effects of pulsed and sinusoid electromagnetic fields on human chondrocytes cultivated in a collagen matrix.

Although several effects of electromagnetic fields (EMFs) on articular cartilage have been reported in recent studies, the use of EMFs to treat osteoarthritis remains a matter of debate. In an in vitro study, human chondrocytes harvested from osteoarthritic knee joints were released from their surrounding matrix and transferred in defined concentration into a 3D matrix (type-I collagen gel). The cultivation, performed under standard conditions, lasted up to 14 days. During this time, treatment groups were continuously exposed to either sinusoid or pulsed electromagnetic fields (PEMFs). The PEMFs revealed the following characteristics: maximum magnetic flux density of 2 mT, frequency of the bursts of 16.7 Hz with each burst consisting of 20 pulses. Similarly, the sinusoid EMFs also induced a maximum flux density of 2 mT with a frequency of 50 Hz. Control groups consisting of equal number of samples were not exposed to EMF. Immunohistological examinations of formalin-fixed, paraffin-embedded samples revealed positive staining for type-II collagen and proteoglycans in the immediate pericellular region with no differences between the two different treatment groups and the control groups. With increasing cultivation time, both type-II collagen and aggrecan gene expression declined, but no significant differences in gene expression were found between the treatment and control groups. In conclusion, using our in vitro setting, we were unable to detect any effects of pulsed and sinusoidal magnetic fields on human adult osteoarthritic chondrocytes.