Effect Of Low-level Laser Treatment Research Articles

Effect of low-level laser treatment on cochlea hair-cell recovery after acute acoustic trauma

We investigated the effect of low-level laser radiation on rescuing hair cells of the cochlea after acute acoustic trauma and hearing loss. Nine rats were exposed to noise. Starting the following day, the left ears (NL ears) of the rats were irradiated at an energy output of 100 to 165 mW/cm(2) for 60 min for 12 days in a row. The right ears (N ears) were considered as the control group. Frequency-specific hearing levels were measured before the noise exposure and also after the 1st, 3rd to 5th, 8th to 10th and 12th irradiations. After the 12th treatment, hair cells were observed using a scanning electron microscope. Compared to initial hearing levels at all frequencies, thresholds increased markedly after noise exposure. After the 12th irradiation, hearing threshold was significantly lower for the NL ears compared to the N ears. When observed using an electron microscope, the number of hair cells in the middle turn of the NL ears was significantly larger than that of the N ears. Our findings suggest that low-level laser irradiation promotes recovery of hearing thresholds after acute acoustic trauma.

Ex Vivo Soft-Laser Treatment Inhibits the Synovial Expression of Vimentin and α-Enolase, Potential Autoantigens in Rheumatoid Arthritis

Soft-laser therapy has been used to treat rheumatic diseases for decades. The major effects of laser treatment may be dependent not on thermal mechanisms but rather on cellular, photochemical mechanisms. However, the exact cellular and molecular mechanisms of action have not been elucidated. The aim of this study was to investigate the ex vivo effects of low-level laser treatment (with physical parameters similar to those applied previously) on protein expression in the synovial membrane in rheumatoid arthritis (RA). Synovial tissues were laser irradiated, and protein expression was analyzed. Synovial membrane samples obtained from 5 people who had RA and were undergoing knee surgery were irradiated with a near-infrared diode laser at a dose of 25 J/cm(2) (a dose used in clinical practice). Untreated synovial membrane samples obtained from the same people served as controls. Synovial protein expression was assessed with 2-dimensional polyacrylamide gel electrophoresis followed by mass spectrometry. The expression of 12 proteins after laser irradiation was different from that in untreated controls. Laser treatment resulted in the decreased expression of α-enolase in 2 samples and of vimentin and precursors of haptoglobin and complement component 3 in 4 samples. The expression of other proteins, including 70-kDa heat shock protein, 96-kDa heat shock protein, lumican, osteoglycin, and ferritin, increased after laser therapy. The relatively small sample size was a limitation of the study. Laser irradiation (with physical parameters similar to those used previously) resulted in decreases in both α-enolase and vimentin expression in the synovial membrane in RA. Both proteins have been considered to be important autoantigens that are readily citrullinated and drive autoimmunity in RA. Other proteins that are expressed differently also may be implicated in the pathogenesis of RA. Our results raise the possibility that low-level laser treatment of joints affected with RA may be effective, at least in part, by suppressing the expression of autoantigens. Further studies are needed.

Effect of laser on TNF-alpha expression in inflamed human gingival tissue

This study sought to evaluate the effect of low-level laser treatment combined with scaling and root planing (SRP) on gingival tissue levels of TNF-alpha in subjects with periodontal disease. Eighty gingival papilla biopsy samples were obtained from 60 patients diagnosed with chronic advanced periodontitis; randomly assigned to three treatment groups (n = 20), as well as 20 subjects with no periodontal disease (group A). Group B received SRP on a single quadrant/day for four consecutive days. On day 5, all quadrants were rescaled. Groups C and D received the same treatment as group B plus laser application with the low-level diode laser (630-670 nm, 1.875 J/cm(2)) for five and ten consecutive days, respectively. Papilla biopsies were obtained from subjects and evaluated by ELISA for levels of TNF-alpha. The values in the control group were 5.2 ± 3.21 pg/mg and baseline values for the examined groups were 46.01 ± 16.69. Significantly decreased level of TNF-alpha for groups C and D was found after treatment, while group B demonstrated reduction of TNF-alpha of 31.34%. The results of this study show suppression of TNF-alpha in gingival tissue after low-level laser treatment as adjunct to SRP. Data may suggest beneficial anti-inflammatory effects of the laser treatment when used as adjunctive periodontal treatment.

Low-level Laser Treatment Relieves Pain and Neurological Symptoms in Patients with Carpal Tunnel Syndrome

[Purpose] This placebo-controlled study investigated the therapeutic effects of low-level laser treatment (LLLT) on the transverse carpal ligament in carpal tunnel syndrome (CTS). [Subjects and Methods] Idiopathic CTS patients were recruited and were randomly assigned to two groups. The laser group (n = 45) received laser treatment (10 Hz, 60 mW, 9.7 J/cm2, 830 nm), and the placebo group (n = 42) received sham laser treatment. The visual analog scale (VAS), Boston Questionnaire scale, neurological symptoms and nerve conduction study (NCS) were conducted before, immediately after and 5 weeks after the treatment. [Results] After LLLT, there was statistically significant decrease in VAS in the laser group (p<0.05). Especially, the effect of LLLT on pain alleviation in the mild CTS group continued after five weeks. Regarding the Boston Questionnaire scale neurological symptoms and NCS, only mild CTS patients in the laser group showed statistically significant improvements after treatment (p<0.05). [Conclusions] LLLT with 830 nm diode lasers on the transverse carpal ligament had verifiable therapeutic effects for mild CTS patients.

Dose-dependent and Ceiling Effects of Therapeutic Laser on Myofascial Trigger Spots in Rabbit Skeletal Muscles

ABSTRACTObjective: To evaluate the effect of low-level laser treatment with different dosages on the irritability of myofascial trigger spots [MTrS] in rabbit skeletal muscles.Methods: Twenty rabbits were equally divided into a low dose group and a high dose group. In each rabbit, the MTrS on the experimental side was irradiated with 660-nm continuous-wave gallium-aluminum-arsenate laser daily for six sessions. The energy per session was 27 J/cm2 [low dose group] and 72 J/cm2 [high dose group]. The MTrS on the other side received sham treatment. The MTrS irritability was assessed with the prevalence of endplate noise [EPN] at baseline after the first and after the last treatments.Results: After the first laser treatment, the EPN prevalence was significantly decreased in both groups. The percentage change in the high dose group was greater than that in the low dose group. The EPN prevalence after the last laser treatment was lower than that after the first laser treatment in the low dose group, but not in ...

Effect of low-level laser treatment of tissue-engineered skin substitutes: contraction of collagen lattices

Fibroblast-populated collagen lattices (FPCL) are widely used in tissue-engineered artificial skin substitutes, but their main drawback is that interaction of fibroblasts and matrix causes contraction of the lattice, reducing it to about 20% of its original area. The effect of low-level laser treatment (LLLT) on the behavior of 3T3 fibroblasts seeded in collagen lattices containing 20% chondroitin-6-sulphate was investigated to determine whether LLLT could control the contraction of FPCL. A He-Ne laser was used at 632.8 nm to deliver a 5-mW continuous wave with fluences from 1 to 4 J/cm(2). Laser treatment at 3 J/cm(2) increased contraction of collagen lattices in the absence of cells but decreased contraction of cell seeded lattices over a 7-day period. The effect was energy dependent and was not observed at 1, 2, or 4 J/cm(2). There was no alteration in fibroblast viability, morphology, or mitochondrial membrane potential after any laser treatments, but the distribution of actin fibers within the cells and collagen fibers in the matrices was disturbed at 3 J/cm(2). These effects contribute to the decrease in contraction observed. LLLT may offer a means to control contraction of FPCL used as artificial skin substitutes.

Effect of low-level laser treatment on neurosensory deficits subsequent to saggittal split ramus osteotomy

Objectives Low-level laser treatment has been advocated as a possible treatment for patients with paresthesia. An objectively verified improvement in sensory function is relevant if, at the same time, it is perceived as a subjective improvement by the patient. The aim of this double blind clinical study was to see if low-level laser treatment with a GaAIAs laser (820 nm, Rønvig, Denmark) resulted in objectively verified improvement in sensory function and whether this correlated with the patient's subjective evaluation subsequent to treatment. Study design The 13 patients in this study had all undergone saggittal split ramus osteotomy resulting in either compression or traction of the inferior alveolar nerve as reported by the surgery notes. The material was collected from a consecutive series of patients at the Karolinska Hospital, all of whom had shown reduced sensibility at their final 2-year postoperative checkup. The patients were randomly divided into two groups; one (eight subjects) group received real low-level laser treatment (4×6 J per treatment along the distribution of the inferior alveolar nerve, at the following points extraoral: lateral third of lower lip, intraoral; buccally to the apex of the second premolar tooth and the apex of the second molar tooth; lingually in the region of the mandibular foramen; for a total of 20 treatments). The other group received an equivalent placebo treatment. The study was conducted in a double blind fashion for both patient and doctor as the low-level laser equipment had two settings, A and B, one of which was an unknown void setting. The degree of mechanoceptor neurosensory deficit was assessed by Semmes Weinstein monofilaments (North Coast Medical, USA) and the degree of thermoceptor neurosensory deficit was assessed by a Thermotester (Somedic, Sweden). The degree of subjective neurosensory deficit was assessed by means of a visual analogue scale. Both variables and the degree of subjective injury were comparable between the two groups before starting treatment. Results The patients in the real low-level laser treatment group experienced a subjective improvement in both lip ( p=0.01) and chin ( p=0.02) after completion of the course of treatment. In addition, this group showed a significant decrease in the area of mechanoperception neurosensory deficit ( p=0.01) compared with no difference in the placebo group. The real low-level laser treatment group exhibited a strong tendency toward improvement in mechanoreceptor neurosensory deficit in the areas of most damage for both lip and chin. This improvement was especially pronounced in the lip region ( p=0.06). No similar tendency was demonstrated in the placebo group. Neither group showed any significant change or tendency to improvement in thermoception on completion of the course of treatment. Conclusions In conclusion GaAIAs low-level laser treatment results in both a subjective and objective improvement in mechanical sensory perception in long-standing neurosensory deficit in the inferior alveolar nerve.

The Effect of Low-level Laser Treatment on Maxillary Arch Dimensions after Palatal Surgery on Beagle Dogs

The effect of low-level laser treatment on maxillary arch dimensions after palatal surgery was investigated in Beagle dogs at an age of 12 weeks. A total of 30 dogs was used, and they were assigned to either a control group (Group C, n = 6) or one of two experimental groups (Group L, n = 12; and group LL, n = 12). After Von Langenbeck's palatal repair in the two experimental groups, denuded bony areas in the LL group were irradiated with a continuous Ga-As-Al laser beam (830 nm) and energy output set at 30 mW. A dosage of 1 J/cm2 wound surface area was used. Treatment was carried out three times a week, with a total of ten treatments. The animals of the L group served as non-treated control animals. Dental casts were made of all animals of all groups at regular intervals until they reached 25 weeks of age. Maxillary arch dimensions were studied. Dental arch dimensions in the deciduous dentition of both experimental groups were not disturbed by surgery, but after eruption of permanent teeth, mainly transverse maxillary arch dimensions in the premolar region increased less in both experimental groups than in the control group. It was concluded that low-level laser treatment under the conditions used in this study did not decrease the adverse iatrogenic effects of palatal surgery on maxillary arch dimensions.