Investigación: Dolor, abstractos y estudios


Photomedicine and Laser Surgery, Volume 30, N2012

Meta-Analysis of Pain Relief Effects by Laser Irradiation on Joint Areas

Ho Jang, M.S., and Hyunju Lee, Ph.D.
Department of Information and Communications, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.


Background: Laser therapy has been proposed as a physical therapy for musculoskeletal disorders and has attained popularity because no side effects have been reported after treatment. However, its true effectiveness is still controversial because several clinical trials have reported the ineffectiveness of lasers in treating pain.

Methods: In this systematic review, we investigate the clinical effectiveness of low-level laser therapy (LLLT) on joint pain. Clinical trials on joint pain satisfying the following conditions are included: the laser is irradiated on the joint area, the PEDro scale score is at least 5, and the effectiveness of the trial is measured using a visual analogue scale (VAS). To estimate the overall effectiveness of all included clinical trials, a mean weighted difference in change of pain on VAS was used.

Results: MEDLINE is the main source of the literature search. After the literature search, 22 trials related to joint pain were selected. The average methodological quality score of the 22 trials consisting of 1014 patients was 7.96 on the PEDro scale; 11 trials reported positive effects and 11 trials reported negative effects. The mean weighted difference in change of pain on VAS was 13.96 mm (95% CI, 7.24–20.69) in favor of the active LLLT groups. When we only considered the clinical trials in which the energy dose was within the dose range suggested in the review by Bjordal et al. in 2003 and in World Association for Laser Therapy (WALT) dose recommendation, the mean effect sizes were 19.88 and 21.05 mm in favor of the true LLLT groups, respectively.

Conclusion: The review shows that laser therapy on the joint reduces pain in patients. Moreover, when we restrict the energy doses of the laser therapy into the dose window suggested in the previous study, we can expect more reliable pain relief treatments.

Efficiency of Low-Level Laser Therapy in Reducing Pain Induced by Orthodontic Forces

Ali Altug Bicakci, D.D.S., M.S., 1Burcu Kocoglu-Altan, D.D.S., M.S., Ph.D.,
2 Hulya Toker, D.D.S., M.S., Ph.D., Ilhan Mutaf, D.D.S., 1 and Zeynep Sumer, M.D., Ph.D. 4


Objective: The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on reducing postadjustment orthodontic pain via evaluation of gingival crevicular fluid (GCF) composition changes at the level of prostaglandin-E2 (PGE2) and visual analogue scale (VAS). Background data: LLLT has been found to be effective in pain relief. PGE2 has the greatest impact on the process of pain signals and can be detected in GCF in order to investigate the response of dental and periodontal tissues in a biochemical manner.

Methods: Nineteen patients (11 females and 8 males; mean age 13.9 years) were included in this study. Maxillary first molars were banded and then a randomly selected first molar at one side was irradiated (820 nm; continuous wave; output power: 50 mW; focal spot: 0.0314 cm2; exposure duration: 5 sec; power density: 1.59 W/cm2; energy dose: 0.25 J; energy density: 7.96 J/cm2 for each shot), while the molar at the other side was served as placebo control. The GCF was collected from the gingival crevice of each molar to evaluate PGE2 levels, before band placement, 1 and 24 h after laser irradiation. Pain intensity was analyzed at 5 min, 1 h, and 24 h after band placement by using VAS.

Results: Although no difference was found in pain perception at 5 min and 1 h, significant reduction was observed with laser treatment 24 h after application ( p < 0.05). The mean PGE2 levels were significantly elevated in control group, whereas a gradual decrease occurred in laser group. The difference in PGE2 levels at both 1 and 24 h were statistically significant between two groups ( p < 0.05).

Conclusion: The significant reductions in both pain intensity and PGE2 levels revealed that LLLT was efficient in reducing orthodontic post-adjustment pain.

Published in "The Lancet"

Efficacy of low-level laser therapy in the management of neck pain: A systematic review and meta-analysis of randomised placebo or active-treatment controlled trials

Dr Roberta T Chow MBBS, Prof Mark I Johnson PhD, Prof Rodrigo AB Lopes-Martins PhD, Prof Jan M Bjordal PT


Background: Neck pain is a common and costly condition for which pharmacological management has limited evidence of efficacy and side-effects. Low-level laser therapy (LLLT) is a relatively uncommon, non-invasive treatment for neck pain, in which non-thermal laser irradiation is applied to sites of pain. We did a systematic review and meta-analysis of randomised controlled trials to assess the efficacy of LLLT in neck pain.

Methods: We searched computerised databases comparing efficacy of LLLT using any wavelength with placebo or with active control in acute or chronic neck pain. Effect size for the primary outcome, pain intensity, was defined as a pooled estimate of mean difference in change in mm on 100 mm visual analogue scale.

Findings: We identified 16 randomised controlled trials including a total of 820 patients. In acute neck pain, results of two trials showed a relative risk (RR) of 1·69 (95% CI 1·22—2·33) for pain improvement of LLLT versus placebo. Five trials of chronic neck pain reporting categorical data showed an RR for pain improvement of 4·05 (2·74—5·98) of LLLT. Patients in 11 trials reporting changes in visual analogue scale had pain intensity reduced by 19·86 mm (10·04—29·68). Seven trials provided follow-up data for 1—22 weeks after completion of treatment, with short-term pain relief persisting in the medium term with a reduction of 22·07 mm (17·42—26·72). Side-effects from LLLT were mild and not different from those of placebo.

Interpretation: We show that LLLT reduces pain immediately after treatment in acute neck pain and up to 22 weeks after completion of treatment in patients with chronic neck pain.

The effect of 300 mW, 830 nm laser on chronic neck pain: a double-blind, randomized, placebo-controlled study.

Chow RT, Heller GZ, Barnsley L.
Castle Hill Medical Centre, 269-271 Old Northern Road, Castle Hill, NSW 2154, Australia.

A randomized, double-blind, placebo-controlled study of low-level laser therapy (LLLT) in 90 subjects with chronic neck pain was conducted with the aim of determining the efficacy of 300 mW, 830 nm laser in the management of chronic neck pain. Subjects were randomized to receive a course of 14 treatments over 7 weeks with either active or sham laser to tender areas in the neck. The primary outcome measure was change in a 10 cm Visual Analogue Scale (VAS) for pain. Secondary outcome measures included Short-Form 36 Quality-of-Life questionnaire (SF-36), Northwick Park Neck Pain Questionnaire (NPNQ), Neck Pain and Disability Scale (NPAD), the McGill Pain Questionnaire (MPQ) and Self-Assessed Improvement (SAI) in pain measured by VAS. Measurements were taken at baseline, at the end of 7 weeks' treatment and 12 weeks from baseline. The mean VAS pain scores improved by 2.7 in the treated group and worsened by 0.3 in the control group (difference 3.0, 95% CI 3.8-2.1). Significant improvements were seen in the active group compared to placebo for SF-36-Physical Score (SF36 PCS), NPNQ, NPAD, MPQVAS and SAI. The results of the SF-36 - Mental Score (SF36 MCS) and other MPQ component scores (afferent and sensory) did not differ significantly between the two groups. Low-level laser therapy (LLLT), at the parameters used in this study, was efficacious in providing pain relief for patients with chronic neck pain over a period of 3 months.

PMID: 16806710 [PubMed - in process

Photoradiation in Acute Pain: A Systematic Review of Possible Mechanisms of Action and Clinical Effects in Randomized Placebo-Controlled Trials

Apr 2006, Vol. 24, No. 2: 158-168 Photomedicine and Laser Surgery

Dr. Jan Magnus Bjordal, P.T., Ph.D.
Section of Physiotherapy Science, University of Bergen, and Institute of Physiotherapy, Bergen University College, Bergen, Norway.

Mark I. Johnson, Ph.D.
Faculty of Health, Leeds Metropolitan University, Leeds, United Kingdom.

Vegard Iversen, Ph.D.
Institute of Biomedical Sciences, Department of Physiology, University of Bergen, Bergen, Norway.

Flavio Aimbire, M.Sc.
Laboratory of Animal Experiments, IP&D Universidade Vale do Paraiba (UNIVAP), São José dos Campos, SP, Brazil.

Rodrigo Alvaro Brandao Lopes-Martins, M.Pharmacol., Ph.D.
Institute of Biomedical Sciences, Pharmacology Department, Universidade Sao Paulo, São Paulo, SP, Brazil.


Objective: The aim of this study was to review the biological and clinical short-term effects of photoradiation in acute pain from soft-tissue injury.

Background data: It is unclear if and how photoradiation can reduce acute pain.

Methods: Literature search of (i) controlled laboratory trials investigating potential biological mechanisms for pain relief and (ii) randomized placebo-controlled clinical trials which measure outcomes within the first 7 days after acute soft-tissue injury.

Results: There is strong evidence from 19 out of 22 controlled laboratory studies that photoradiation can modulate inflammatory pain by reducing levels of biochemical markers (PGE2, mRNA Cox 2, IL-1β, TNFα), neutrophil cell influx, oxidative stress, and formation of edema and hemorrhage in a dose-dependent manner (median dose 7.5 J/cm2, range 0.3–19 J/cm2). Four comparisons with non-steroidal anti-inflammatory drugs (NSAIDs) in animal studies found optimal doses of photoradiation and NSAIDs to be equally effective. Seven randomized placebo-controlled trials found no significant results after irradiating only a single point on the skin overlying the site of injury, or after using a total energy dose below 5 Joules. Nine randomized placebo-controlled trials (n = 609) were of acceptable methodological quality, and irradiated three or more points and/or more than 2.5 cm2 at site of injury or surgical incision, with a total energy of 5.0–19.5 Joules.

Results in these nine trials were significantly in favor of photoradiation groups over placebo groups in 15 out of 18 outcome comparisons. Poor and heterogeneous data presentation hampered statistical pooling of continuous data. Categorical data of subjective improvement were homogeneous (Q-value = 7.1) and could be calculated from four trials (n = 379) giving a significant relative risk for improvement of 2.7 (95% confidence interval [CI], 1.8–3.9) in a fixed effects model.

Conclusion: photoradiation can modulate inflammatory processes in a dose-dependent manner and can be titrated to significantly reduce acute inflammatory pain in clinical settings. Further clinical trials with adequate photoradiation doses are needed to precisely estimate the effect size for photoradiation in acute pain.

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Braz Dent J. 2001;12(3):187-90.

Assessment Of Anti-Inflammatory Effect Of 830nm Laser Light Using C-Reactive Protein Levels.

Freitas AC, Pinheiro AL, Miranda P, Thiers FA, Vieira AL.
Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, PUC-RS, Porto
Alegre, RS, Brazil.

The anti-inflammatory effect of non-surgical lasers has been proposed previously, however it was not scientifically proven. One method to assess levels of inflammation is the measurement of C-reactive protein (CRP), which is increased with the course of inflammation. The aim of this study was to assess the effect of 830 nm laser irradiation after the removal of impacted third molars using the CRP as the marker of inflammation.

Twelve patients were irradiated with 4.8 J of laser light per session 24 and 48 h after surgery. A control group (N = 12) was treated with a sham laser. Blood samples were taken prior to, and 48 and 72 h after surgery. CRP values were more symmetric and better distributed for the irradiated group (0.320 mg/dl) than for the control ( 48 h after surgery, however there was no statistically significant difference. After 72 h, both groups had statistically similar CRP levels (0.272 and 0.608 mg/dl), because of the normal tendency of decreasing CRP levels.