Effect of photobiomodulation therapy with different wavelengths on bone mineral density in osteoporotic rats

The Effect of Photobiomodulation on Bone Mineral Density, Serum Vitamin D, and Bone Formation Markers in Individuals with Complete Spinal Cord Injuries with Osteoporosis

Study design: A quasi-experimental study utilized a matched-pair design, administering photobiomodulation at four-sites on one side of the body and assigning control to the other side at corresponding sites. Objectives: This study aimed to assess photobiomodulation treatment effects on bone mineral density (BMD) measurement using dual-energy X-ray-absorptiometry in individuals with complete spinal cord injury (C.SCI) and osteoporosis. Methods: Eight patients received treatment at four-sites: forearm-mid-distal (MID), proximal-femur, distal-femur, and proximal-tibia, totaling 32 sites. Using an 830 nm gallium-aluminum-arsenide semiconductor laser irradiation was administered three times weekly for 8 weeks. Different doses (energy density) were determined depending on bone depth from skin surface, as assessed by sonography and adjusted through irradiation time to be 8, 10, and 12 J/cm2 for depths <1 cm, between 1 and 1.5 cm, and >1.5 cm, respectively, using 200 mW power to deliver the optimal isodose of laser at each depth of bone within each therapeutic site. BMD was measured at baseline, week 8 of treatment, and week 15 of follow-up. Serum 25-(OH)-vitamin D and bone formation markers including osteocalcin and bone-alkaline-phosphatase (B-ALP) were also assessed at baseline and week 8 of treatment. Results: Significant increases in BMD were noted in proximal-femur and forearm-MID at both week 8 and week 15. Serum 25-(OH)-vitamin D levels significantly increased after treatment. However, no notable changes were observed in distal-femur and proximal-tibia BMD or in osteocalcin and B-ALP levels. Conclusions: Photobiomodulation (830 nm) laser demonstrated efficacy in improving BMD at proximal-femur and forearm-MID in individuals with C.SCI. Moreover, the observed positive influence on vitamin D levels suggests a potential photobiomodulation role, warranting further investigation.

The role of photobiomodulation in accelerating bone repair

Bone repair is faced with obstacles such as slow repair rates and limited bone regeneration capacity. Delayed healing even nonunion could occur in bone defects, influencing the life quality of patients severely. Photobiomodulation (PBM) utilizes different light sources to derive beneficial therapeutic effects with the advantage of being non-invasive and painless, providing a promising strategy for accelerating bone repair. In this review, we summarize the parameters, mechanisms, and effects of PBM regulating bone repair, and further conclude the current clinical application of PBM devices in bone repair. The wavelength of 635-980 nm, the output power of 40-100 mW, and the energy density of less than 100 J/cm2 are the most commonly used parameters. New technologies, including needle systems and biocompatible and implantable optical fibers, offer references to realize an efficient and safe strategy for bone repair. Further research is required to establish the reliability of outcomes from in vivo and in vitro studies and to standardize clinical trial protocols.

The effect of photobiomodulation therapy in common maxillofacial injuries: Current status

The use of photobiomodulation therapy (PBMT) may be used for treating trauma to the maxillofacial region. The effects of PBMT on maxillofacial injuries were discussed in this review article. The electronic databases Pubmed, Scopus, and Web of Science were thoroughly searched. This review included in vitro, in vivo, and clinical studies describing how PBMT can be used in maxillofacial tissue engineering and regenerative medicine. Some studies suggest that PBMT may offer a promising therapy for traumatic maxillofacial injuries because it can stimulate the differentiation and proliferation of various cells, including dental pulp cells and mesenchymal stem cells, enhancing bone regeneration and osseointegration. PBMT reduces pain and swelling after oral surgery and tooth extraction in human and animal models of maxillofacial injuries. Patients with temporomandibular disorders also benefit from PBMT in terms of reduced inflammation and symptoms. PBMT still has some limitations, such as the need for standardizing parameters. PBMT must also be evaluated further in randomized controlled trials in various maxillofacial injuries. As a result, PBMT offers a safe and noninvasive treatment option for patients suffering from traumatic maxillofacial injuries. PBMT still requires further research to establish its efficacy in clinical practice and determine the optimal parameters.

Dosimetry in cranial photobiomodulation therapy: effect of cranial thickness and bone density

This research aims to examine the influence of human skull bone thickness and density on light penetration in PBM therapy across different wavelengths, focusing on how these bone characteristics affect the absorption of therapeutic light. Analyses explored the effect of skull bone density and thickness on light penetration in PBM, specifically using Low-Level Laser Therapy (LLLT) for efficacy prediction. Measurements of bone thickness and density were taken using precise tools. This approach emphasizes LLLT's significance in enhancing PBM outcomes by assessing how bone characteristics influence light penetration. The study revealed no significant correlation between skull bone density and thickness and light penetration capability in photobiomodulation (PBM) therapy, challenging initial expectations. Wavelengths of 405 nm and 665 nm showed stronger correlations with bone density, suggesting a significant yet weak impact. Conversely, wavelengths of 532 nm, 785 nm, 810 nm, 830 nm, 980 nm, and 1064 nm showed low correlations, indicating minimal impact from bone density variations. However, data variability (R2 < 0.4) suggests that neither density nor thickness robustly predicts light power traversing the bone, indicating penetration capability might be more influenced by bone thickness at certain wavelengths. The study finds that the effectiveness of photobiomodulation (PBM) therapy with bone isn't just based on bone density and thickness but involves a complex interplay of factors. These include the bone's chemical and mineral composition, light's wavelength and energy dose, treatment duration and frequency, and the precise location where light is applied on the skull.