استفاده از مطالب اين صفحه تنها باذكر منبع و لينك اين سايت مجاز است

The Nuts and Bolts of Low-level Laser (Light) Therapy.

Chung H, Dai T, Sharma SK, Huang YY, Carroll JD, Hamblin MR

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA.

Soon after the discovery of lasers in the 1960s it was realized that laser therapy had the potential to improve wound healing and reduce pain, inflammation and swelling. In recent years the field sometimes known as photobiomodulation has broadened to include light-emitting diodes and other light sources, and the range of wavelengths used now includes many in the red and near infrared. The term “low level laser therapy” or LLLT has become widely recognized and implies the existence of the biphasic dose response or the Arndt-Schulz curve. This review will cover the mechanisms of action of LLLT at a cellular and at a tissular level and will summarize the various light sources and principles of dosimetry that are employed in clinical practice. The range of diseases, injuries, and conditions that can be benefited b y LLLT will be summarized with an emphasis on those that have reported randomized controlled clinical trials. Serious life-threatening diseases such as stroke, heart attack, spinal cord injury, and traumatic brain injury may soon be amenable to LLLT therapy.

Ann Biomed Eng 2011 Nov

A randomised clinical trial of the effect of low-level laser therapy for perineal pain and healing after episiotomy: A pilot study.

Santos JD, Oliveira SM, Nobre MR, Aranha AC, Alvarenga MB

Health Sciences Institute, University Paulista, Rua Apeninos, 267, CEP 01533-000, Sao Paulo, Brazil.

OBJECTIVE: to evaluate the effects of low-level laser therapy for perineal pain and healing after episiotomy. DESIGN: a double-blind, randomised, controlled clinical trial comparing perineal pain scores and episiotomy healing in women treated with low-level laser therapy (LLLT) and with the simulation of the treatment. SETTING: the study was conducted in the Birth Centre and rooming-in units of Amparo Maternal, a maternity service located in the city of Sao Paulo, Brazil. PARTICIPANTS: fifty-two postpartum women who had had mediolateral episiotomies during their first normal delivery were randomly divided into two groups of 26: an experimental group and a control group. INTERVENTION: in the experimental group, the women were treated with LLLT. Irradiation was applied at three points directly on the episiotomy after the suture a nd in three postpartum sessions: up to 2hrs postpartum, between 20 and 24hrs postpartum and between 40 and 48hrs postpartum. The LLLT was performed with diode laser, with a wavelength of 660nm (red light), spot size of 0.04cm(2), energy density of 3.8J/cm(2), radiant power of 15mW and 10s per point, which resulted in an energy of 0.15J per point and a total energy of 0.45J per session. The control group participants also underwent three treatment sessions, but without the emission of radiation (simulation group), to assess the possible effects of placebo treatment. MAIN OUTCOMES: perineal pain scores, rated on a scale from 0 to 10, were evaluated before and immediately after the irradiation in the three sessions. The healing process was assessed using the REEDA scale (Redness, Edema, Echymosis, Discharge Aproximation) before each laser therapy session and 15 and 20 days after the women’s discharge. FINDINGS: comparing the pain scores before and after the LLLT sessions, the experimental group presented a significant within-group reduction in mean pain scores after the second and third sessions (p=0.003 and p<0.001, respectively), and the control group showed a significant reduction after the first treatment simulation (p=0.043). However, the comparison of the perineal pain scores between the experimental and control groups indicated no statistical difference at any of the evaluated time points. There was no significant difference in perineal healing scores between the groups. All postpartum women approved of the low-level laser therapy. CONCLUSIONS: this pilot study showed that LLLT did not accelerate episiotomy healing. Although there was a reduction in perineal pain mean scores in the experimental group, we cannot conclude that the laser relieved perineal pain. This study led to the suggestion of a new research proposal involving another irradiation protocol to evaluate LLLT’s effect on perineal pain relief.

Midwifery 2011 Oct 5

 

Dose response effects of 810 nm laser light on mouse primary cortical neurons.

Sharma SK, Kharkwal GB, Sajo M, Huang YY, De Taboada L, McCarthy T, Hamblin MR

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts; Department of Dermatology, Harvard Medical School, Boston, Massachusetts.

BACKGROUND AND OBJECTIVES: In the past four decades numerous studies have reported the efficacy of low level light (laser) therapy (LLLT) as a treatment for diverse diseases and injuries. Recent studies have shown that LLLT can biomodulate processes in the central nervous system and has been extensively studied as a stroke treatment. However there is still a lack of knowledge on the effects of LLLT at the cellular level in neurons. The present study aimed to study the effect of 810 nm laser on several cellular processes in primary cortical neurons cultured from embryonic mouse brains. STUDY DESIGN/MATERIALS AND METHODS: Neurons were irradiated with fluences of 0.03, 0.3, 3, 10, or 30 J/cm(2) of 810-nm laser delivered over varying times at 25 mW/cm(2) and intracellular levels of reactive oxygen species (ROS), nitric oxide and calci um were measured using fluorescent probes within 5 minutes of the end of irradiation. The changes in mitochondrial function in response to light were studied in terms of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP). RESULTS: Light induced a significant increase in calcium, ATP and MMP at lower fluences and a decrease at higher fluences. ROS was significantly induced at low fluences, followed by a decrease and a second larger increase at 30 J/cm(2) . Nitric oxide levels showed a similar pattern of a double peak but values were less significant compared to ROS. CONCLUSIONS: The results suggest that LLLT at lower fluences is capable of inducing mediators of cell signaling processes which in turn may be responsible for the beneficial stimulatory effects of the low level laser. At higher fluences beneficial mediators are reduced and high levels of Janus-type mediators such as ROS and NO (beneficial at low concentrations and harmful at high concentration s) may be responsible for the damaging effects of high-fluence light and the overall biphasic dose response. Lasers Surg. Med. (c) 2011 Wiley-Liss, Inc.

Lasers Surg Med 2011 Sep 43(8) 851-9

Cytomorphometric and clinical investigation of the gingiva before and after low-level laser therapy of gingivitis in children.

Igic M, Mihailovic D, Kesic L, Milasin J, Apostolovic M, Kostadinovic L, Janjic OT

Department of Children and Preventive Dentistry, Dental Clinic, Medical Faculty Nis, University of Nis, Bul dr Zorana Djindjica 52, 18000, Nis, Serbia, igicmarija@gmail.com.

Gingival epithelial cells are the first physical barrier against periodontal pathogenic microorganisms. Bacterial products may penetrate the epithelium and directly disturb its integrity. We investigated the clinical and cytomorphological status of the gingiva in children with gingivitis before and after low-level laser therapy. The study enrolled 130 children divided into three groups: group 1 comprised 50 children with chronic catarrhal gingivitis who received basic treatment, group 2 comprised 50 children with chronic catarrhal gingivitis who received low-level laser treatment in addition to basic treatment, and group 3 comprised 30 children with healthy gingiva as controls. Oral hygiene and the status of the gingiva were assessed using the appropriate indexes before and after treatment. Inflammation of the gingiva wa s monitored by cytomorphometric evaluation. Cytomorphometric analysis revealed a statistically significant difference (p < 0.001) in the size of the nuclei of the stratified squamous epithelial cells of the gingiva before and after treatment in chronic catarrhal gingivitis. Evaluation using clinical parameters showed that treatment of gingivitis with basic treatment was successful. Cytomorphometric analysis showed that after basic treatment the nuclei of the stratified squamous epithelial cells of the gingiva were reduced in size, although not to the size found in healthy gingiva. However, after adjuvant low-level laser therapy, the size of the nuclei of the stratified squamous epithelial cells in the gingiva matched the size of the nuclei in the cells in healthy gingiva.

Lasers Med Sci 2011 Sep 29

[Low power laser efficacy in the therapy of inflamed gingive in diabetics with parodontopathy].

Obradovic R, Kesic L, Jovanovic G, Petrovic D, Goran R, Mihailovic D

Medicinski fakultet, Klinika za stomatologiju, Odeljenje za oralnu medicinu i parodontologiju, Nis, Srbija. dr.rada@yahoo.com

BACKGROUND/AIM: There is clear evidence on direct relationship between periodontal disease and diabetes mellitus. Many investigations point out greater prevalence and severity of periodontal disease among diabetic patients. During last decade, low level laser therapy has been used in periodontal therapy. It has biostimulative effect, accelerates wound healing, minimizes pain and swelling, and there is almost no contraindication for its usage. The aim of the paper was to investigate the efficiency of low level laser therapy as adjuvant tool in reduction of gingival inflammation in diabetic patients. METHODS: The study incuded 150 participants divided into three groups: group I (50 participants with diabetes mellitus type 1 and periodontal disease), group II (50 participants with diabetes mellitus type 2 and periodontal di sease), group III (nondiabetic participants with periodontal disease). Gingival health evaluation was done using gingival index Loe-Silness. Soft and hard deposits were removed, periodontal pockets cleaned and GaA1As low level laser therapy (5 mW) applied five consecutive days. In each patient, low level laser therapy was not applied on the left side of the jaw in order to compare the effects of the applied therapy. After the first, third and fifth therapy and one month after the last visit gingival index was evaluated. Before the first and after the fifth therapy exfoliative cytology of gingiva was done and nuclei areal was analyzed morphometrically. RESULTS: After all investigated periods, gingival index and nuclei areal were significantly decreased comparing to values before the therapy, at both jaw sides (p < 0.001). After the 1st, 3rd and 5th therapy, the t-test showed a significantly decreased gingival index at the lased side of jaw comparing to non-lased side. CONC LUSION: Low level laser therapy is efficient in gingival inflammation elimination and can be proposed as an adjuvant tool in basic periodontal therapy of diabetic patients.

Vojnosanit Pregl 2011 Aug 68(8) 684-9

Comparison of Therapeutic Effects between Pulsed and Continuous Wave 810-nm Wavelength Laser Irradiation for Traumatic Brain Injury in Mice.

Ando T, Xuan W, Xu T, Dai T, Sharma SK, Kharkwal GB, Huang YY, Wu Q, Whalen MJ, Sato S, Obara M, Hamblin MR

Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America.

BACKGROUND AND OBJECTIVE: Transcranial low-level laser therapy (LLLT) using near-infrared light can efficiently penetrate through the scalp and skull and could allow non-invasive treatment for traumatic brain injury (TBI). In the present study, we compared the therapeutic effect using 810-nm wavelength laser light in continuous and pulsed wave modes in a mouse model of TBI. STUDY DESIGN/MATERIALS AND METHODS: TBI was induced by a controlled cortical-impact device and 4-hours post-TBI 1-group received a sham treatment and 3-groups received a single exposure to transcranial LLLT, either continuous wave or pulsed at 10-Hz or 100-Hz with a 50% duty cycle. An 810-nm Ga-Al-As diode laser delivered a spot with diameter of 1-cm onto the injured head with a power density of 50-mW/cm(2) for 12-minutes giving a fluence of 36-J/cm(2 ). Neurological severity score (NSS) and body weight were measured up to 4 weeks. Mice were sacrificed at 2, 15 and 28 days post-TBI and the lesion size was histologically analyzed. The quantity of ATP production in the brain tissue was determined immediately after laser irradiation. We examined the role of LLLT on the psychological state of the mice at 1 day and 4 weeks after TBI using tail suspension test and forced swim test. RESULTS: The 810-nm laser pulsed at 10-Hz was the most effective judged by improvement in NSS and body weight although the other laser regimens were also effective. The brain lesion volume of mice treated with 10-Hz pulsed-laser irradiation was significantly lower than control group at 15-days and 4-weeks post-TBI. Moreover, we found an antidepressant effect of LLLT at 4-weeks as shown by forced swim and tail suspension tests. CONCLUSION: The therapeutic effect of LLLT for TBI with an 810-nm laser was more effective at 10-Hz pulse frequency than at C W and 100-Hz. This finding may provide a new insight into biological mechanisms of LLLT.

PLoS One 2011 6(10) e26212

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