The efficacy of low-level 940 nm laser therapy with different energy intensities on bone healing

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.

Evaluation of the effects of platelet-rich fibrin and diode laser on gingival blood perfusion and early bone healing of the extraction socket: a randomized controlled clinical trial

Evaluation and comparison of the effect of platelet-rich fibrin (PRF), diode laser, and combination of PRF and diode laser on gingival blood perfusion and early bone formation of the extraction socket. Forty maxillary premolar sockets were randomized to four groups: control group, PRF group, diode laser group, and PRF + diode laser group. Gingival blood perfusion was measured at preoperative and postoperative 1, 3, 7, and 30 days. Fractal dimension analysis was performed immediately after the procedure and in the postoperative first month. Gingival perfusions significantly increased during 1 week compared to baseline for all groups with a mean of -4.43 ± 3.20, -5.99 ± 3.68, -5.45 ± 3.01, and -4.78 ± 2.82 respectively, and were at baseline 1 month later. There were no statistically significant differences between the groups at any time point. Although the increase of fractal dimension was higher in the PRF or diode laser group than in the control group with a mean of 0.085 ± 0.05, 0.100 ± 0.04, and 0.072 ± 0.04 respectively, no statistically significant differences were detected. Fractal dimension was significantly greater in PRF + diode laser group than in the control group with a mean of 0.138 ± 0.05 (p = 0.04). PRF, diode laser, and PRF + diode laser did not significantly affect the gingival perfusion, and the combined application of PRF and diode laser had positive effects on early bone regeneration in the extraction socket. PRF, diode laser, and PRF + diode laser provide better tissue healing of the extraction socket.

Photobiomodulation therapy at red and near-infrared wavelengths for osteogenic differentiation in the scaffold-free microtissues

One of the novel strategies for bone tissue regeneration is photobiomodulation (PBM) which depends on the red and near-infrared light absorption by mitochondria and may trigger bone tissue regeneration via the production of intracellular ROS and ATP, NO release, etc. It is also important to identify the changes in those signal molecule levels in an in vivo mimicking platform such as 3-Dimensional (3D) Scaffold Free Microtissues (SFMs) that may serve more natural osteogenic differentiation responses to PBM. Herein, we aimed to increase the osteogenic differentiation capability of the co-culture of Human Bone Marrow Stem Cells (hBMSC) and Human Umbilical Vein Endothelial Cells (HUVECs) on 3D SFMs by triple light treatment at 655 and 808-nm of wavelengths with the energy densities of 1, 3, and 5 J/cm². We performed the analysis of cell viability, diameter measurements of SFMs, intracellular ROS production, NO release, ATP activity, temperature measurements, DNA content, ALPase activity, calcium content, and relative gene expressions of ALP, Collagen, and Osteopontin by qRT-PCR. It was found that both wavelengths were effective in terms of the viability of SFMs. 1 and 5 J/cm² energy densities of both wavelengths increased the SFM diameter with significant changes in intracellular ROS, ATP, and NO levels compared to the control group. We concluded that PBM therapy was successful to induce osteogenesis. 1 J/cm² at 655 nm of wavelength and 5 J/cm² at 808 nm of wavelength were the most effective energy densities for osteogenic differentiation on SFMs with triple light treatment.

Use of Photobiomodulation Combined with Fibrin Sealant and Bone Substitute Improving the Bone Repair of Critical Defects

In this preclinical protocol, an adjunct method is used in an attempt to overcome the limitations of conventional therapeutic approaches applied to bone repair of large bone defects filled with scaffolds. Thus, we evaluate the effects of photobiomodulation therapy (PBMT) on the bone repair process on defects filled with demineralized bovine bone (B) and fibrin sealant (T). The groups were BC (blood clot), BT (B + T), BCP (BC + PBMT), and BTP (B + T + PBMT). Microtomographically, BC and BCP presented a hypodense cavity with hyperdense regions adjacent to the border of the wound, with a slight increase at 42 days. BT and BTP presented discrete hyperdensing areas at the border and around the B particles. Quantitatively, BCP and BTP (16.96 ± 4.38; 17.37 ± 4.38) showed higher mean bone density volume in relation to BC and BT (14.42 ± 3.66; 13.44 ± 3.88). Histologically, BC and BCP presented deposition of immature bone at the periphery and at 42 days new bone tissue became lamellar with organized total collagen fibers. BT and BTP showed inflammatory infiltrate along the particles, but at 42 days, it was resolved, mainly in BTP. In the birefringence analysis, BT and BTP, the percentage of red birefringence increased (9.14% to 20.98% and 7.21% to 27.57%, respectively), but green birefringence was similar in relation to 14 days (3.3% to 3.5% and 3.5% to 4.2%, respectively). The number of osteocytes in the neoformed bone matrix proportionally reduced in all evaluated groups. Immunostaining of bone morphogenetic protein (BMP—2/4), osteocalcin (OCN), and vascular endothelial growth factor (VEGF) were higher in BCP and BTP when compared to the BC and BT groups (p < 0.05). An increased number of TRAP positive cells (tartrate resistant acid phosphatase) was observed in BT and BTP. We conclude that PBMT positively influenced the repair of bone defects filled with B and T.

Reconstruction of Soft Biological Tissues Using Laser Soldering Technology with Temperature Control and Biopolymer Nanocomposites

Laser soldering is a current biophotonic technique for the surgical recovery of the integrity of soft tissues. This technology involves the use of a device providing laser exposure to the cut edges of the wound with a solder applied. The proposed solder consisted of an aqueous dispersion of biopolymer albumin (25 wt.%), single-walled carbon nanotubes (0.1 wt.%) and exogenous indocyanine green chromophore (0.1 wt.%). Under laser exposure, the dispersion transforms into a nanocomposite due to the absorption of radiation and its conversion into heat. The nanocomposite is a frame structure of carbon nanotubes in a biopolymer matrix, which provides adhesion of the wound edges and the formation of a strong laser weld. A new laser device based on a diode laser (808 nm) has been developed to implement the method. The device has a temperature feedback system based on a bolometric infrared matrix sensor. The system determines the hottest area of the laser weld and adjusts the current supplied to the diode laser to maintain the preset laser heating temperature. The laser soldering technology made it possible to heal linear defects (cuts) in the skin of laboratory animals (rabbits) without the formation of a fibrotic scar compared to the control (suture material). The combined use of a biopolymer nanocomposite solder and a laser device made it possible to achieve a tensile strength of the laser welds of 4 ± 0.4 MPa. The results of the experiment demonstrated that the addition of single-walled carbon nanotubes to the solder composition leads to an increase in the ultimate tensile strength of the laser welds by 80%. The analysis of regenerative and morphological features in the early stages (1-3 days) after surgery revealed small wound gaps, a decrease in inflammation, the absence of microcirculatory disorders and an earlier epithelization of laser welds compared to the control. On the 10th day after the surgical operation, the laser weld was characterized by a thin cosmetic scar and a continuous epidermis covering the defect. An immunohistochemical analysis proved the absence of myofibroblasts in the area of the laser welds.

Effect of low-level laser therapy on condylar growth in children treated with functional appliance: a preliminary study

Purpose

This study aimed to evaluate the skeletal and dentoalveolar changes achieved by combining low-level laser irradiation applied on the condyle area with twin-block therapy in growing class II malocclusion patients.

Methods

Fourteen patients (9 males, 5 females; mean age, 11.4 ± 2 years) with skeletal class II mandibular deficiency were recruited. They were divided into two groups (G 1: twin-block + low-level laser therapy, G 2: twin-block only). A semiconductor diode laser with a wavelength of 940 nm was applied on the condyle area (100 mW, 2.5 J, 3.9 J/cm²). The laser was applied twice a week in the first month and once a week in the second and third months, totalizing 16 sessions. Skeletal, dental, and soft-tissue cephalometric parameters were measured and compared at different treatment points.

Results

Mandibular length (Co-Gn) was significantly increased by 3.6 mm in the experiment group (3.16 SD) and 4.3 mm (4.4 SD) in the control group, with no significant difference between groups at every time point (P-value 0.949 at T2). Similarly, a statistically significant positive effect of treatment was found in both groups on ramus height (Co-Go), upper lip to E-Line, SNA angle, ANB angle, and U1/SN angle with no significant difference between groups.

Conclusion

Based on the results of this preliminary study, low-level laser irradiation with the used parameters seems to have no synergetic impact on the skeletal and dental outcomes of twin-block therapy over 9 months. However, more studies are needed to investigate the effect of low-level laser therapy on condylar growth during functional orthodontic treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41547-022-00158-x.

In vivo efficacy of low-level laser therapy on bone regeneration

PURPOSE

In clinical use of low-level laser therapy for bone regeneration (LLLT), application protocol (dose, duration, and repetitions) has not been established. This study aimed to depict a reliable dosage of LLLT by evaluating the efficacy of different dosing of LLLT (diode) on the healing of rabbit cranial defects.

METHODS

Critical size defects were prepared in calvarias of 26 New Zealand White Rabbits in such each animal containing both test and control groups. Test groups were irradiated with 4 Joule/cm² (j/cm²), 6 j/cm², and 8 j/cm². The rabbits were subjected to six times of laser treatments in 10 days. At the end of the second week, 5 rabbits were sacrificed for histopathological and immunohistochemical analyses. At the 4th and 8th weeks, 20 rabbits (10 each) were sacrificed for micro-CT and histopathological analyses.

RESULTS

Micro-CT evaluation revealed improved new bone formation in all test groups compared to the control group. 6 j/cm² group demonstrated the highest bone formation. The highest bone morphogenic protein -2 levels were found in the 4 j/cm² group. Osteocalcin expression was significantly higher in 4 j/cm² group.

CONCLUSIONS

Our findings indicate that LLLT have a positive effect on new bone formation. The high efficacy of doses of 4 j/cm² and 6 j/cm² is promising to promote early bone healing.

Effect of S53P4 bioactive glass and low-level laser therapy on calvarial bone repair in rats submitted to zoledronic acid therapy

PURPOSE

To evaluate the influence of bioactive glass and photobiomodulation therapy (PBMT) in calvarial bone repair process in rats submitted to zoledronic acid therapy.

METHODS

Twenty-four rats were selected and treated with the dose of 0.035 mg/kg of zoledronic acid every two weeks, totalizing eight weeks, to induce osteonecrosis. After the drug therapy, surgical procedure was performed to create 5-mm diameter parietal bone defects in the calvarial region. The rats were then randomly assigned to groups according to the following treatments: AZC: control group, treated with blood clot; AZBIO: bone defect filled with bioactive glass; AZL: treated with blood clot and submitted to PBMT; and AZBIOL: treated with bioactive glass S53P4 and submitted to PBMT. Tissue samples were collected and submitted to histomorphometric analysis after 14 and 28 days.

RESULTS

At 14 days, bone neoformation in the AZBIO (52.15 ± 9.77) and AZBIOL (49.77 ± 13.58) groups presented higher values (p ≤ 0.001) compared to the AZC (23.35 ± 10.15) and AZL groups (23.32 ± 8.75). At 28 days, AZBIO (80.24 ± 5.41)still presented significant higher bone recovery values when compared to AZC (59.59 ± 16.92)and AZL (45.25 ± 5.41) groups (p = 0.048). In the 28-day period, the AZBIOL group didn't show statistically significant difference with the other groups (71.79 ± 29.38).

CONCLUSIONS

The bioactive glass is an effective protocol to stimulate bone neoformation in critical defects surgically created in rats with drug induced osteonecrosis, in the studied periods of 14 and 28 days.

Low-Level Laser Light Therapy Dosage Variables vs Treatment Efficacy of Neuromusculoskeletal Conditions: A Scoping Review

OBJECTIVE

The purpose of this scoping review was to identify and synthesize literature on dosage variables on the efficacy of low-level laser therapy (LLLT) for neuromusculoskeletal conditions.

METHODS

A scoping literature review was conducted by searching the following databases: the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature, Medline, the Physiotherapy Evidence Database, the Index to Chiropractic Literature, manufacturer websites, and online guidelines. The search was modeled after STARLITE criteria. The reporting used Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews (PRISMA-ScR). Articles were included if LLLT was used in any treatment group for a neuromusculoskeletal complaint with dosage and effectiveness reported. This was tabulated by source, dosage variables, conditions, outcome measures, and conclusions. Data were charted in Excel format. Frequency counts were performed on ordinal data. Descriptive statistics were computed for the continuous data.

RESULTS

A total of 86 articles were included in the review. They revealed a broad range of musculoskeletal conditions and diverse dosage parameters. Seven individual parameters were found that would alter the dosage. Although duration of application is an independent clinical factor, the negative-outcome studies were inconsistent in duration. There was lack of statistical difference between the studies with improved vs unimproved outcomes. No statistical differences were noted between the dosage parameters and efficacy.

CONCLUSION

Although many articles were found on LLLT for neuromusculoskeletal conditions, the studies had amorphous parameters. A heterogeneity of reported doses precluded the synthesis of sufficient evidence to correlate dosage variables with improved or unimproved outcomes. Therefore, based on the current literature, dosage variables for the efficacy of LLLT for neuromusculoskeletal conditions are uncertain at this time.

Photobiomodulation therapy (PBMT) in bone repair: A systematic review

BACKGROUND

Photobiomodulation therapy (PBMT) using low-level laser influences the release of several growth factors involved in the formation of epithelial cells, fibroblasts, collagen and vascular proliferation, besides accelerating the synthesis of bone matrix due to the increased vascularization and lower inflammatory response, with significant increase of osteocytes in the irradiated bone. Considering its properties, beneficial effects and clinical relevance, the aim of this review was to analyze the scientific literature regarding the use of PBMT in the process of bone defect repair.

METHODS

Electronic search was carried out in PubMed/MEDLINEⓇ and Web of Science databases with combination of the descriptors low-level laser therapy AND bone repair, considering the period of publication until the year 2018.

RESULTS

The literature search identified 254 references in PubMed/MEDLINE and 204 in Web of Science, of which 33 and 4 were selected, respectively, in accordance with the eligibility requirements. The analysis of researches showed articles using PBMT in several places of experimentation in the subjects, different types of associated biomaterials, stimulatory effects on cell proliferation, besides variations in the parameters of use of laser therapy, mainly in relation to the wavelength and density of energy. Only four articles reported that the laser did not improve the osteogenic properties of a biomaterial.

CONCLUSIONS

Many studies have shown that PBMT has positive photobiostimulatory effects on bone regeneration, accelerating its process regardless of parameters and the use of biomaterials. However, standardization of its use is still imperfect and should be better studied to allow correct application concerning the utilization protocols.

Association of Bioglass/Collagen/Magnesium composites and low level irradiation: effects on bone healing in a model of tibial defect in rats

Background and Aims

Bioglass (BG) and Magnesium (Mg) composites have been used for bone tissue engineering proposes due to its osteogenic activity and increased mechanical properties respectively. The introduction of Collagen (Col) is a common and efficient approach for bone tissue engineering applications toward cell proliferation. Recently, studies demonstrated that BG/Col/Mg composites presented proper mechanical properties and were non-cytotoxic. Although the osteogenic potential of BG/Col/Mg composites, in specific situations, biomaterials may not be capable of stimulating bone tissue. Therefore, combining biomaterial matrices and effective post-operative therapies (such as low level lasertherapy; LLLT) may be necessary to appropriately stimulate bone tissue. In this context, the aim of this study was to develop intra- and extra-operatively bone regenerative therapeutical strategies, based on the association of Col-enriched BG/Mg composites with LLLT.

Materials and Methods

Thereby, an in vivo study, using tibial defect in Wistar rats, was performed in order to investigate the bone regenerative capacity. LLLT treatment (Ga-Al-As laser 808 nm, 30 mW, 2.8 J, 94 s) was performed 3 times a week, in non-consecutive days. Histology, histomorphometry, immunohistochemical analysis and mechanical test were done after 15 and 45 days post-implantation.

Results

The results showed that Col could be successfully introduced into BG/Mg and the association of BG/Mg/Col and LLLT constituted an optimized treatment for accelerating material degradation and increasing bone deposition. Additionally, mechanical tests showed an increased maximal load for BG/Mg + LLLT compared to other groups.

Conclusions

These results lead us to conclude that the Col enriched BG/Mg composites irradiated with LLLT presented superior biological and mechanical properties, demonstrating to be a promising bone graft.