Photobiomodulation Therapy (PBMT) in Peripheral Nerve Regeneration: A Systematic Review

Photobiomodulation Therapy (PBMT) Applied in Bone Reconstructive Surgery Using Bovine Bone Grafts: A Systematic Review

The use of low-level laser therapy (LLLT) with biomodulatory effects on biological tissues, currently called photobiomodulation therapy (PBMT), assists in healing and reduces inflammation. The application of biomaterials has emerged in bone reconstructive surgery, especially the use of bovine bone due to its biocompatibility. Due to the many benefits related to the use of PBMT and bovine bones, the aim of this research was to review the literature to verify the relationship between PBMT and the application of bovine bone in bone reconstruction surgeries. We chose the PubMed/MEDLINE, Web of Science, and Scopus databases for the search by matching the keywords: "Bovine bone AND low-level laser therapy", "Bovine bone AND photobiomodulation therapy", "Xenograft AND low-level laser therapy", and "Xenograft AND photobiomodulation therapy". The initial search of the three databases retrieved 240 articles, 18 of which met all inclusion criteria. In the studies concerning animals (17 in total), there was evidence of PBMT assisting in biomaterial-related conduction, formation of new bone, bone healing, immunomarker expression, increasing collagen fibers, and local inflammation reduction. However, the results disagreed with regard to the resorption of biomaterial particles. The only human study showed that PBMT with bovine bone was effective for periodontal regeneration. It was concluded that PBMT assists the process in bone reconstruction when associated with bovine bone, despite divergences between applied protocols.

Effects of a single treatment with two nonthermal laser wavelengths on chronic neck and shoulder pain

Introduction

Nonthermal lasers provide pain relief for a variety of musculoskeletal disorders and improve physical functioning. A nonthermal laser that employs a 635 nm red diode is cleared for the temporary reduction of neck and shoulder pain of musculoskeletal origin. As a 405 nm violet laser has shown synergy with the 635 nm red laser when used together for treating other conditions, the objective of this study was to compare the efficacy of 635 nm red and 405 nm violet lasers vs the 635 nm red laser for treating neck and shoulder pain of musculoskeletal origin.

Materials and methods

Otherwise healthy adult subjects with chronic neck or shoulder pain for ≥30 days were enrolled and randomized to receive a single 13-min treatment with combined red and violet lasers (n=44) or the red laser alone (n=43). The primary efficacy measure was change in baseline VAS pain scores 3 mins after treatment. Subject success was predefined as a ≥30% decrease in VAS scores and study success was predefined as 65±5% individual subject successes.

Results

Among subjects treated with the red and violet lasers, mean VAS neck and shoulder pain scores decreased from 65.0 to 35.2 (p<0.0001). Most subjects in the study (75%) achieved ≥30% decrease in VAS scores. The decreased mean (SD) VAS scores remained 29.6 (16.7) and 29.3 (19.2) after 24 and 48 hrs, respectively. The secondary efficacy measures of change in range of motion ROM) and patient satisfaction also improved. There were no adverse events.

Conclusion

Overall, treatment with the red and violet lasers outperformed the FDA-approved red laser with respect to change in pain scores and improvement in shoulder ROM.

Comparative effects of photobiomodulation therapy at wavelengths of 660 and 808 nm on regeneration of inferior alveolar nerve in rats following crush injury

The aim of the present study was to investigate the therapeutic effects of 660-nm and 880-nm photobiomodulation therapy (PBMT) following inferior alveolar nerve (IAN) crush injury. Following the nerve crush injuries of IAN, 36 Wistar rats were randomly divided into three groups as follows: (1) control, (2) 660-nm PBMT, and (3) 808-nm PBMT (GaAlAs laser, 100 J/cm², 70 mW, 0.028-cm² beam). PBMT was started immediately after surgery and performed once every 3 days during the postoperative period. At the end of the 30-day treatment period, histopathological and histomorphometric evaluations of tissue sections were made under a light and electron microscope. The ratio of the inner axonal diameter to the total outer axonal diameter (g-ratio) and the number of axons per square micrometer were evaluated. In the 808-nm PBMT group, the number of nerve fibers with suboptimal g-ratio ranges of 0-0.49 (p < 0.001) is significantly lower than expected, which indicates better rate of myelinization in the 808-nm PBMT group. The number of axons per square micrometer was significantly higher in the 808-nm PBMT group when compared with the control (p < 0.001) and 660-nm PBMT group (p = 0.010). The data and the histopathological investigations suggest that the PBMT with the 808-nm wavelength along with its settings was able to enhance IAN regeneration after nerve crush injury.

Photobiomodulation therapy as a tool to prevent hamstring strain injuries by reducing soccer-induced fatigue on hamstring muscles

Muscle fatigue is a potential risk factor for hamstring strain injuries in soccer players. The aim of this study was to verify the effect of photobiomodulation therapy (PBMT) on the hamstrings' muscle fatigue of soccer players during a simulated match. Twelve male amateur soccer players (~ 25 years) participated in this randomized, crossover, double-blinded, placebo-controlled trial. The volunteers were evaluated in two sessions, with a minimum 7-day interval. At each session, volunteers received either PBMT (300 J per thigh) or placebo treatment on the hamstrings prior to the simulated soccer match. Muscle strength and functional capacity were evaluated through isokinetic dynamometry and countermovement jump (CMJ) tests, respectively, before and immediately after the simulated soccer match. Players had lower reductions on hamstring eccentric peak torque [4.85% (ES = 0.31) vs. 8.72% (ES = 0.50)], hamstring-to-quadriceps torque ratio [3.60% (ES = 0.24) vs. 7.75% (ES = 0.50)], and CMJ height [1.77% (ES = 0.09) vs. 5.47% (ES = 0.32)] when treated with PBMT compared to placebo. Magnitude-based inference supports that PBMT promoted 75%, 69%, and 53% chances for beneficial effects on hamstring eccentric peak torque, hamstring-to-quadriceps torque ratio, and CMJ height, respectively, compared to placebo treatment. In conclusion, PBMT applied before a simulated soccer match proved to be effective in attenuating the hamstrings' muscle fatigue. These findings support PBMT as a promising tool to prevent hamstring strain injury in soccer players.