The effects of laser irradiation on osteoblast and osteosarcoma cell proliferation and differentiation in vitro

Effect of Low-Level Diode Laser and Red Light-Emitting Diode on Survival and Osteogenic/Odontogenic Differentiation of Human Dental Pulp Stem Cells

Background: This investigation set out to compare the impacts of low-level diode laser (LLDL) and red light-emitting diode (LED) on the survival of human dental pulp stem cells (hDPSCs) and osteogenic/odontogenic differentiation. Methods and materials: In this ex vivo experimental study, the experimental groups underwent the irradiation of LLDL (4 J/cm2 energy density) and red LED in the osteogenic medium. Survival of hDPSCs was assessed after 24 and 48 h (n = 9) using the methyl thiazolyl tetrazolium (MTT) assay. The assessment of osteogenic/odontogenic differentiation was conducted using alizarin red staining (ARS; three repetitions). The investigation of osteogenic and odontogenic gene expression was performed at two time points, specifically 24 and 48 h (n = 12). This analysis was performed utilizing real-time reverse-transcription polymerase chain reaction (RT-PCR). The groups were compared at each time point using SPSS version 24. To analyze the data, the Mann-Whitney U test, analysis of variance, Tukey's test, and t-test were utilized. Results: The MTT assay showed that LLDL significantly decreased the survival of hDPSCs after 48 h, compared with other groups (p < 0.05). The qualitative results of ARS revealed that LLDL and red LED increased the osteogenic differentiation of hDPSCs. LLDL and red LED both upregulated the expression of osteogenic/odontogenic genes, including bone sialoprotein (BSP), alkaline phosphatase (ALP), dentin matrix protein 1 (DMP1), and dentin sialophosphoprotein (DSPP), in hDPSCs. The LLDL group exhibited a higher level of gene upregulation (p < 0.0001). Conclusions: The cell survival of hDPSCs was reduced, despite an increase in osteogenic/odontogenic activity. Clinical relevance: Introduction of noninvasive methods in regenerative endodontic treatments.

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.

Effects of low level laser on periodontal tissue remodeling in hPDLCs under tensile stress

This study aimed to investigate the effect of Low-Level Laser Therapy (LLLT) on human Periodontal Ligament Cells (hPDLCs) under tension stress. Primary hPDLCs were obtained using the tissue culture method, and P3 cells were utilized for the subsequent experiments. The study comprised four groups: a blank control group (Group B), a laser irradiation group (Group L), a tension stress group (Group T), and a laser + tension stress group (Group LT). Mechanical loading was applied using an in-vitro cell stress loading device at a frequency of 0.5 Hz and deformation of 2% for two hours per day for two days. Laser irradiation at 808 nm GaAlAs laser was administered 1 h after force loading. Cell samples were collected after the experiment. Bone and fiber remodeling factors were analyzed using PCR and Western blot. Flow cytometry was employed to assess the cell cycle, while ROS and Ca2+ levels were measured using a multifunctional enzyme labeling instrument. The results revealed that laser intervention under tension stress inhibited the expression of osteogenic differentiation factors, promoted the expression of osteoclast differentiation factors, and significantly increased the production of collagen factors, MMPs, and TIMPs. The LT group exhibited the most active cell cycle (P < 0.05). LLLT not only enhanced Ca2+ expression in hPDLCs under tension stress, but also stimulated the production of ROS. Overall, our findings demonstrate that LLLT effectively accelerated the proliferation of hPDLCs and the remodeling of periodontal tissue, possibly through the regulation of ROS and Ca2+ levels in hPDLCs.

Alveolar Ridge Augmentation Assessment Using a Minimalistic Approach, with and without Low-Level Laser Therapy (LLLT)-A Comparative Clinical Trial

Background and Objective: A narrow alveolar ridge is an obstacle to optimal rehabilitation of the dentition. There are several complex and invasive techniques to counter the ridge augmentation dilemma, with most of them exhibiting low feasibility. Hence, this randomized clinical trial aims to evaluate the effectiveness of a Minimalistic Ridge Augmentation (MRA) technique, in conjunction with low-level laser therapy (LLLT). Materials and Methods: A total of 20 patients (n = 20) were selected, with 10 assigned to the test group (MRA+LLLT) and the other 10 to the control group (MRA). A vertical incision of approximately 10 mm was placed mesial to the defect and tunneled to create a subperiosteal pouch across the entire width of the defect. At the test sites, a diode laser (AnARC Fox^TM Surgical Laser 810 nm) was used to deliver LLLT (parameters: 100 mW, with a maximum energy distribution of 6 J/cm² in the continuous wave mode for 60 s per point) to the exposed bone surface inside the pouch, followed by graft (G-Graft, Surgiwear^TM, Shahjahanpur, India) deposition with a bone graft carrier. The control sites were not irradiated with a laser. Results: A horizontal ridge width gain of >2 mm was observed in both groups. The changes in bone density for the test and control groups were -136 ± 236.08 HU and -44.30 ± 180.89 HU, respectively. Furthermore, there was no statistically significant difference between the test and control groups in these parameters. Conclusion: The study findings reveal that the MRA technique is relatively simple and feasible for alveolar ridge augmentation. The role of LLLT in the process requires further elucidation.

Effects of different physical factors on osteogenic differentiation

Osteoblasts are essential for bone formation and can perceive external mechanical stimuli, which are translated into biochemical responses that ultimately alter cell phenotypes and respond to environmental stimuli, described as mechanical transduction. These cells actively participate in osteogenesis and the formation and mineralisation of the extracellular bone matrix. This review summarises the basic physiological and biological mechanisms of five different physical stimuli, i.e. light, electricity, magnetism, force and sound, to induce osteogenesis; further, it summarises the effects of changing culture conditions on the morphology, structure and function of osteoblasts. These findings may provide a theoretical basis for further studies on bone physiology and pathology at the cytological level and will be useful in the clinical application of bone formation and bone regeneration technology.

Possible adverse effects of low-level laser on oral and oropharyngeal cancer cells: A scope review

BACKGROUND

The effects of laser therapy on normal cells are well known and accepted, but the impact of this therapy on malignant cells are not yet fully understood. This review aims to map and outline what the scientific literature addresses on the effects of laser therapy on malignant cells.

METHODS

This review article followed the guidelines of the PRISMA-ScR protocol, being all the search, analysis, and selection of articles based on it.

RESULTS

After all application of the predetermined criteria, five studies were included, dated between the years 2013 and 2021. With the complete reading of the selected studies, 100% of the articles were classified as category III of the Agency for Healthcare as Research and Quality classification. Similar themes among the papers included were investigated and compared. In these five studies, the visible red and near infrared wavelengths were used, and energy densities varied between 1 and 5 J/cm² . It was observed that low-level laser could alter the expression of cell proliferation and migration proteins, such as cyclin D1, E-cadherin, and β-catenin. In addition, changes related to increased cell viability and metabolism were also identified.

CONCLUSION

The low-level laser seems to positively regulate the proliferative, migratory, and viability capacity of neoplastic cells, depending on the protocol used. All these studies included in the review are equivalent to in vitro studies; the cells are not in such a complex environment as is an organized tissue, making it necessary to carry out more complex tests, such as in vivo research.

Investigating effects of locally applied boric acid on fracture healing with and without low-level laser therapy

This study aimed to investigate the effects on fracture healing of locally applied boric acid (BA) with and without low-level laser therapy (LLLT). A unicortical femoral defect was surgically created on the anterolateral surface of proximal femur of each subject. The subjects, totaling 56 Wistar albino rats, were randomly allocated into four groups (n = 14 each): control, LLLT (λ = 905 μm, 10,000 Hz, 25 mW, and peak power 25 W), BA (40 mg/kg), and BA + LLLT groups. On the 30th day, the highest radiological score was recorded for the BA + LLLT group (3.63 [2-4]), followed by the BA (3.38 [2.75-3.75]), control (3 [2-3.25]), and LLLT (2.5 [1.25-3]) groups. On days 15 and 30 post-surgery, malondialdehyde levels were significantly lower among the BA + LLLT group compared to the control group (p < 0.001). On day 30, superoxide dismutase, catalase, and alkaline phosphatase levels were highest in the BA + LLLT group compared to the control group (p < 0.001). When the histopathological, immunofluorescence, and immunohistochemical findings on the 15th and 30th days were compared with the control group, a statistically significant difference was found for the BA and BA + LLLT groups (p ˂ 0.05). This study suggests that locally applied BA with LLLT may accelerate fracture healing.

Progress of phototherapy for osteosarcoma and application prospect of blue light photobiomodulation therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor that mainly affects the pediatric and adolescent population; limb salvage treatment has become one of the most concerned and expected outcomes of OS patients recently. Phototherapy (PT), as a novel, non-invasive, and efficient antitumor therapeutic approach including photodynamic therapy (PDT), photothermal therapy (PTT), and photobiomodulation therapy (PBMT), has been widely applied in superficial skin tumor research and clinical treatment. OS is the typical deep tumor, and its phototherapy research faces great limitations and challenges. Surprisingly, pulse mode LED light can effectively improve tissue penetration and reduce skin damage caused by high light intensity and has great application potential in deep tumor research. In this review, we discussed the research progress and related molecular mechanisms of phototherapy in the treatment of OS, mainly summarized the status quo of blue light PBMT in the scientific research and clinical applications of tumor treatment, and outlooked the application prospect of pulsed blue LED light in the treatment of OS, so as to further improve clinical survival rate and prognosis of OS treatment and explore corresponding cellular mechanisms.

Photobiomodulation therapy in management of cancer therapy-induced side effects: WALT position paper 2022

Disclaimer

This article is based on recommendations from the 12th WALT Congress, Nice, October 3-6, 2018, and a follow-up review of the existing data and the clinical observations of an international multidisciplinary panel of clinicians and researchers with expertise in the area of supportive care in cancer and/or PBM clinical application and dosimetry. This article is informational in nature. As with all clinical materials, this paper should be used with a clear understanding that continued research and practice could result in new insights and recommendations. The review reflects the collective opinion and, as such, does not necessarily represent the opinion of any individual author. In no event shall the authors be liable for any decision made or action taken in reliance on the proposed protocols.

Objective

This position paper reviews the potential prophylactic and therapeutic effects of photobiomodulation (PBM) on side effects of cancer therapy, including chemotherapy (CT), radiation therapy (RT), and hematopoietic stem cell transplantation (HSCT).

Background

There is a considerable body of evidence supporting the efficacy of PBM for preventing oral mucositis (OM) in patients undergoing RT for head and neck cancer (HNC), CT, or HSCT. This could enhance patients’ quality of life, adherence to the prescribed cancer therapy, and treatment outcomes while reducing the cost of cancer care.

Methods

A literature review on PBM effectiveness and dosimetry considerations for managing certain complications of cancer therapy were conducted. A systematic review was conducted when numerous randomized controlled trials were available. Results were presented and discussed at an international consensus meeting at the World Association of photobiomoduLation Therapy (WALT) meeting in 2018 that included world expert oncologists, radiation oncologists, oral oncologists, and oral medicine professionals, physicists, engineers, and oncology researchers. The potential mechanism of action of PBM and evidence of PBM efficacy through reported outcomes for individual indications were assessed.

Results

There is a large body of evidence demonstrating the efficacy of PBM for preventing OM in certain cancer patient populations, as recently outlined by the Multinational Association for Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). Building on these, the WALT group outlines evidence and prescribed PBM treatment parameters for prophylactic and therapeutic use in supportive care for radiodermatitis, dysphagia, xerostomia, dysgeusia, trismus, mucosal and bone necrosis, lymphedema, hand-foot syndrome, alopecia, oral and dermatologic chronic graft-versus-host disease, voice/speech alterations, peripheral neuropathy, and late fibrosis amongst cancer survivors.

Conclusions

There is robust evidence for using PBM to prevent and treat a broad range of complications in cancer care. Specific clinical practice guidelines or evidence-based expert consensus recommendations are provided. These recommendations are aimed at improving the clinical utilization of PBM therapy in supportive cancer care and promoting research in this field. It is anticipated these guidelines will be revised periodically.

Hybrid laser activated phycocyanin/capecitabine treatment of cancerous MCF7 cells

Laser-induced fluorescence is recently used as an efficient technique in cancer diagnosis and non-invasive treatment. Here, the synergic therapeutical efficacies of the Capecitabine (CAP) chemodrug, photosensitive Phycocyanin (PC) and graphene oxide (GO) under laser irradiation were investigated. The therapeutical efficacies of diverse concentrations of CAP (0.001-10 mg/ml) and PC (0.5-10 mg/ml) alone and with laser irradiation on human breast adenocarcinoma (MCF-7) cells were examined. The interactional effects of 100 mW SHG Nd:YAG laser at 532nm and GaAs laser at 808 nm ranging power of 150 mW- 2.2W were considered. The contribution of graphene oxide (GO) in biocompatible concentrations of 2.5-20 ng/ml and thermal characteristics of laser exposure at 808 nm on GO + fluorophores have been studied. The effects of the bare and laser-excited CAP + PC on cell mortality have been obtained. Despite the laser irradiation could not hold up the cell proliferation in the absence of drug interaction considerably; however, the viability of the treated cells (by a combination of fluorophores) under laser exposure at 808 nm was significantly reduced. The laser at 532 nm excited the fluorescent PC in (CAP + PC) to trigger the photodynamic processes via oxygen generation. Through the in-vitro experiments of laser-induced fluorescence (LIF) spectroscopy of PC + CAP, the PC/CAP concentrations of the maximum fluorescence signal and spectral shifts have been characterized. The synergic effects of the laser exposures and (CAP + PC) treatment at different concentrations were confirmed. It has been shown here that the laser activation of (CAP + PC) can induce the mortality of the malignant cells by reducing the chemotherapeutic dose of CAP to avoid its non-desirable side effects and by approaching the minimally invasive treatment. Elevation of the laser intensity/exposure time could contribute to the therapeutic efficacy. Survival of the treated cells with a combination of GO and fluorophores could be reduced under laser exposure at 808 nm compared to the same combination therapy in the absence of GO. This survey could benefit the forthcoming clinical protocols based on laser spectroscopy for in-situ imaging/diagnosis/treatment of adenocarcinoma utilizing PC + CAP + GO.

Management of Combined Therapy (Ceritinib, A. cinnamomea, G. lucidum, and Photobiomodulation) in Advanced Non-Small-Cell Lung Cancer: A Case Report

The 5-year survival rate of non-small-cell lung cancer (NSCLC) is still low (<21%) despite recent improvements. Since conventional therapies have a lot of side effects, combined therapy is strongly recommended. Here, we report a patient with advanced NSCLC who received combined therapy, including ceritinib, photobiomodulation (PBM), ACGL (Antrodia cinnamomea (A. cinnamomea), and Ganoderma lucidum (G. lucidum)). Based on combined therapy, suitable doses of A. cinnamomea, G. lucidum, and PBM are important for tumor inhibition. This case report presents clinical evidence on the efficacy of combined therapy in advanced NSCLC patients, including computed tomography (CT) scan, magnetic resonance imaging (MRI), carcinoembryonic antigen (CEA), and blood tests. The effective inhibition of human lung adenocarcinoma cells is demonstrated. Our case highlights important considerations for PBM and ACGL applications in NSCLC patients, the side effects of ceritinib, and long-term health maintenance.

The different irradiation parameters of carbon dioxide laser effects on periodontal ligament cells

Background

Materials and methods

Results

Conclusion

Photobiomodulation Therapy Affects the Elastic Modulus, Cytoskeletal Rearrangement and Migration Capability of Human Osteosarcoma Cells

Photobiomodulation (PBM) therapy utilizes low-power lasers to modulate the viability of living human cells and leads to changes in proliferation, differentiation, adhesion and gene expression, even though the rearrangement of cytoskeleton was not previously studied. The present study aims to evaluate the photobiological effects on the elastic behavior of human osteosarcoma cells (MG-63) and their morphological changes. Fluorescence staining, confocal imaging and atomic force microscopy (AFM) topography were performed to study the effects of PBM therapy with the exposure of 532 nm-25mW, 650 nm-3mW, 650 nm-150mW and 780 nm-70mW beams following the 5-min continuous irradiation. The area of each beam was 3.14cm² with a source-surface distance of 20 cm. Besides the cell proliferation assessment, the migratory potential of MG-63 was determined with the wound healing technique. The results indicated an increase in stiffness and shape index of radiation-induced cells 24 h after exposure along with the obvious F-actins changes. But, cell stiffening was not observed 72 h after 532 nm laser irradiation. Also, a decrease in the migration rate was seen in all of the groups after 72 h of irradiation except cells treated with 532 nm wavelength. However, 532 nm laser beams increase the migratory potential 24 h after exposure. Within 72 h after irradiation, the cell proliferation was only affected by applying 532 nm and 650 nm-150mW laser beams. It was concluded that applying photobiomodulation with wavelengths of 650 nm (at both utilized powers) and 780 nm alters the migration capability and provides a quantitative description of cytoskeletal changes. Moreover, membrane stiffening can be considered as the biological marker of PBM treatments.

Innovative Concepts and Recent Breakthrough for Engineered Graft and Constructs for Bone Regeneration: A Literature Systematic Review

Background: For decades, regenerative medicine and dentistry have been improved with new therapies and innovative clinical protocols. The aim of the present investigation was to evaluate through a critical review the recent innovations in the field of bone regeneration with a focus on the healing potentials and clinical protocols of bone substitutes combined with engineered constructs, growth factors and photobiomodulation applications. Methods: A Boolean systematic search was conducted by PubMed/Medline, PubMed/Central, Web of Science and Google scholar databases according to the PRISMA guidelines. Results: After the initial screening, a total of 304 papers were considered eligible for the qualitative synthesis. The articles included were categorized according to the main topics: alloplastic bone substitutes, autologous teeth derived substitutes, xenografts, platelet-derived concentrates, laser therapy, microbiota and bone metabolism and mesenchymal cells construct. Conclusions: The effectiveness of the present investigation showed that the use of biocompatible and bio-resorbable bone substitutes are related to the high-predictability of the bone regeneration protocols, while the oral microbiota and systemic health of the patient produce a clinical advantage for the long-term success of the regeneration procedures and implant-supported restorations. The use of growth factors is able to reduce the co-morbidity of the regenerative procedure ameliorating the post-operative healing phase. The LLLT is an adjuvant protocol to improve the soft and hard tissues response for bone regeneration treatment protocols.

Efficacy of Photobiomodulation and Vitamin D on Odontogenic Activity of Human Dental Pulp Stem Cells

Introduction: The regeneration of dental pulp tissue using human dental pulp stem cells (HDPSCs) has attracted increasing attention in recent years. Recent studies have suggested that several factors such as photobiomodulation (PBM) and vitamin D affect the proliferation and differentiation of HDPSCs. Therefore, the present study evaluated the effects of PBM and vitamin D on odontogenic differentiation of HDPSCs for dentin -like tissue formation. Methods: HDPSCs were collected, isolated, and characterized and then divided into six groups: group I, control; group II, vitamin D (10^-7 Mol); group III, irradiation at 1 J/cm² of 810 nm diode laser; group IV, irradiation at 1 J/cm² and culture with vitamin D; group V, irradiation at 2 J/cm², and group VI, irradiation at 2 J/cm² and culture with vitamin D, cell viability assay was measured through MTT. Alkaline phosphatase (ALP) enzyme activity and mRNA levels of vascular endothelial growth factor (VEGF), bone morphogenic protein-2 (BMP-2), and dentin sialophosphoprotein (DSPP) were also assessed. Results: PBM at 1 and 2 J/cm² combined with vitamin D significantly promoted HDPSCs proliferation through MTT assay and odontogenic differentiation through gene expression of VEGF, BMP-2, and DSPP levels (P < 0.0001). Conclusion: PBM at 2 J/cm² combined with vitamin D enhanced the HDPSCs proliferation and odontogenic differentiation and thus could be a novel strategy for dentin regeneration in dentistry.

The Effects of Photobiomodulation on Bone Defect Repairing in a Diabetic Rat Model

The purpose of this study is to examine the prospective therapeutic effects of photobiomodulation on the healing of bone defects in diabetic mellitus (DM) using rat models to provide basic knowledge of photobiomodulation therapy (PBMT) during bone defect repair. For in vitro study, an Alizzarin red stain assay was used to evaluate the effect of PBMT on osteogenic differentiation. For in vivo study, micro-computed tomography (microCT) scan, H&E and IHC stain analysis were used to investigate the effect of PBMT on the healing of the experimental calvarial defect (3 mm in diameter) of a diabetic rat model. For in vitro study, the high glucose groups showed lower osteogenic differentiation in both irradiated and non-irradiated with PBMT when compared to the control groups. With the PBMT, all groups (control, osmotic control and high glucose) showed higher osteogenic differentiation when compared to the non-irradiated groups. For in vivo study, the hyperglycemic group showed significantly lower bone regeneration when compared to the control group. With the PBMT, the volume of bone regeneration was increasing and back to the similar level of the control group. The treatment of PBMT in 660 nm could improve the bone defect healing on a diabetic rat calvarial defect model.

Effects of photobiomodulation on glucose homeostasis and morphometric parameters in pancreatic islets of diabetic mice

High-fat diets lead to accumulation of body fat that is associated with the onset of insulin resistance and type II diabetes mellitus. On the other hand, photobiomodulation (PBM) is an electrophysical resource that interacts with cells, stimulating mitochondrial respiration, increasing ATP production, reducing key inflammatory mediators, inhibiting apoptosis, and stimulating angiogenesis. However, little is known about its therapeutic effectiveness on the development of diabetes in diet-induced obese mice. Thus, our aim was to evaluate the effect of PBM applied single point over the pancreas area on glucose homeostasis, insulin expression, and pancreatic morphometric parameters of mice submitted to high-fat diet for 12 weeks. Male mice C57BL6/J were divided into three groups: control group (C), diabetic group (D), and diabetic + PBM (D + PBM). The treatment with PBM started at 9th week and ended in the 12th week, applied 3 × /week. Body mass, fast blood glucose, and glucose and insulin tolerance were evaluated. Immunohistochemistry to detect insulin expression and pancreatic morphometry were also performed. At the end of 12th week, both groups submitted to high-fat diet showed an increase in body mass, adiposity, disturbances on glucose homeostasis, and high insulin expression when compared to the control group. However, mice treated with PBM had more discrete impairments on glucose homeostasis during the glucose tolerance test when compared to untreated D animals. Despite modest, the results were positive and encourage future investigations to explore different doses and duration of PBM to better elucidate its role in obesity-associated type 2 diabetes development.

Indirect Structural Muscle Injuries of Lower Limb: Rehabilitation and Therapeutic Exercise

Muscle injuries are the most common trauma in team and individual sports. The muscles most frequently affected are those of the lower limb, and in particular hamstrings, adductors, rectus femoris and calf muscles. Although several scientific studies have tried to propose different rehabilitation protocols, still too often the real rehabilitation process is not based on scientific knowledge, especially in non-elite athletes. Moreover, the growing use of physical and instrumental therapies has made it increasingly difficult to understand what can be truly effective. Therefore, the aim of the present paper is to review proposed therapeutic algorithms for muscle injuries, proposing a concise and practical summary. Following a three-phase rehabilitation protocol, this review aims to describe the conservative treatment of indirect structural muscle injuries, which are the more routinely found and more challenging type. For each phase, until return to training and return to sport are completed, the functional goal, the most appropriate practitioner, and the best possible treatment according to current evidence are expressed. Finally, the last section is focused on the specific exercise rehabilitation for the four main muscle groups with a structured explanatory timetable.

The Effect of Photobiomodulation on Human Mesenchymal Cells: A Literature Review

BACKGROUND

Mesenchymal stem cell-based therapy is known to have the potential to induce angiogenesis. However, there are still some limitations regarding their clinical application. Photomodulation/photobiomodulation is non-invasive and non-toxic phototherapy able to stimulate cell viability, proliferation, differentiation, and migration, when the right irradiation parameters are applied. A review of the published articles on human conditioned-by-photobiomodulation mesenchymal cells in an in vitro set up was carried out. Our aim was to describe the studies' results and identify any possible tendency that might highlight the most suitable procedures.

METHODS

A search in English of the PubMed database was carried out with the search criteria: photobiomodulation or photoactivation or photomodulation, and mesenchymal cells. All irradiations applied in vitro, on human mesenchymal cells, with wavelengths ranged from 600 to 1000 nm.

RESULTS

The search yielded 42 original articles and five reviews. Finally, 37 articles were selected with a total of 43 procedures. Three procedures (7.0%) from 620 to 625 nm; 26 procedures (60.5%) from 625 to 740 nm; 13 procedures (30.2%) from 740 to 1000 nm; and one procedure (2.3%) with combinations of wavelengths. Of the 43 procedures, 14 assessed cell viability (n = 14/43, 32.6%); 34 cell proliferation (n = 34/43, 79.1%); 19 cell differentiation (n = 19/43, 44.2%); and three cell migration (n = 3/43, 7.0%).

CONCLUSIONS

Photobiomodulation is a promising technology that can impact on cell viability, differentiation, proliferation, or migration, leading to enhance its regenerative capacity.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Photobiomodulation by Near-Infrared 980-nm Wavelengths Regulates Pre-Osteoblast Proliferation and Viability through the PI3K/Akt/Bcl-2 Pathway

BACKGROUND

bone tissue regeneration remains a current challenge. A growing body of evidence shows that mitochondrial dysfunction impairs osteogenesis and that this organelle may be the target for new therapeutic options. Current literature illustrates that red and near-infrared light can affect the key cellular pathways of all life forms through interactions with photoacceptors within the cells' mitochondria. The current study aims to provide an understanding of the mechanisms by which photobiomodulation (PBM) by 900-nm wavelengths can induce in vitro molecular changes in pre-osteoblasts.

METHODS

The PubMed, Scopus, Cochrane, and Scholar databases were used. The manuscripts included in the narrative review were selected according to inclusion and exclusion criteria. The new experimental set-up was based on irradiation with a 980-nm laser and a hand-piece with a standard Gaussian and flat-top beam profile. MC3T3-E1 pre-osteoblasts were irradiated at 0.75, 0.45, and 0.20 W in continuous-wave emission mode for 60 s (spot-size 1 cm²) and allowed to generate a power density of 0.75, 0.45, and 0.20 W/cm² and a fluence of 45, 27, and 12 J/cm², respectively. The frequency of irradiation was once, three times (alternate days), or five times (every day) per week for two consecutive weeks. Differentiation, proliferation, and cell viability and their markers were investigated by immunoblotting, immunolabelling, fluorescein-FragELTM-DNA, Hoechst staining, and metabolic activity assays.

RESULTS AND CONCLUSIONS

The 980-nm wavelength can photobiomodulate the pre-osteoblasts, regulating their metabolic schedule. The cellular signal activated by 45 J/cm², 0.75 W and 0.75 W/cm² consist of the PI3K/Akt/Bcl-2 pathway; differentiation markers were not affected, nor do other parameters seem to stimulate the cells. Our previous and present data consistently support the window effect of 980 nm, which has also been described in extracted mitochondria, through activation of signalling PI3K/Akt/Bcl-2 and cyclin family, while the Wnt and Smads 2/3-β-catenin pathway was induced by 55 J/cm², 0.9 W and 0.9 W/cm².

Comparison of Single and Multiple Low-Level Laser Applications After Rapid Palatal Expansion on Bone Regeneration in Rats

Introduction: This study was performed to compare the effects of single and multiple irradiations of low-level laser therapy (LLLT) on bone regeneration in a mid-palatal suture following rapid palatal expansion (RPE). Methods: In this animal study, 40 male Wistar rats underwent RPE for 7 days and were divided into 4 groups including A: single LLLT on day 7, B: Multiple LLLT on days 7, 9, 11, 13 and 15, C: control (no LLLT), and D: sacrificed on day 7. Animals in group D were used to determine the amount of suture expansion. LLLT was done by a diode laser set at an 808 nm wavelength with a useful power output of 100 mW and duration of 0.1 ms. LLLT was applied to three points. After three weeks of retention, the rats were sacrificed and beheaded and the maxilla was evaluated by occlusal radiography, µ-CT, and histomorphometric analyses. A comparison of the mean measurements between the groups was performed using ANOVA and the Tukey post hoc test. Results: Based on occlusal radiography and µCT, bone density in group B was significantly higher than group A and group C (P<0.05). There was no significant difference in bone density between group A and group C (P>0.05). Mean suture width (MSW) in group B was significantly lesser than the control group (P=0.027) while there was no significant difference between MSWnin groups A and B (P=0.116) and groups A and C (P=0.317). Conclusion: It may be concluded that multiple low-power laser irradiation improves bone regeneration after RPE while single irradiation does not have a positive effect.

Induced photo-cytotoxicity on prostate cancer cells with the photodynamic action of toluidine Blue ortho

BACKGROUND

Photodynamic therapy (PDT) has become an advantageous therapeutic approach for the treatment of select cancers and microbial infections. PDT generates toxic reactive oxygen species as an end product of the interaction between the photosensitizer and light with an appropriate wavelength. Toluidine blue ortho is a photosensitizer that is commonly used in the photodynamic treatment of bacterial infection and a promising photosensitizer for cancer treatment. This study aims to evaluate the potential photo-cytotoxicity of toluidine blue ortho-mediated photodynamic therapy on PC-3 prostate cancer cells.

METHODS

In this study toluidine blue ortho-mediated photodynamic therapy was assessed on PC-3 cancer cells with various photosensitizer concentrations and light energy densities of the 655-nm diode laser. MTT analysis was used for the determination of the cytotoxicity on the cells and viability/cytotoxicity assay was used for live/dead cell staining after the applications. The mechanism of this application was further analyzed with the determination of intracellular reactive oxygen species and nitric oxide release.

RESULTS

The light applications and the photosensitizer alone did not inhibit the cell viability of PC-3 cells. 20 J/cm² laser energy density together with 100 μM photosensitizer concentration resulted in maximum cancer cell death with a rate of approximately 89 %. The level of intracellular reactive oxygen species increased with the increasing parameters of the applications that resulted in more cell death.

CONCLUSION

This study showed the successful anticancer activity of toluidine blue ortho upon irradiation with 655 nm of laser light against PC-3 cancer cells and it was mediated with the production of reactive oxygen species.

Laser treatment of synovial inflammatory process in experimentally induced microcrystalline arthritis in Wistar rats

The presence of intra-articular crystals is detected in different articular pathologies of acute or chronic nature. The aim of this work was to analyze the action of the indium gallium aluminum and phosphorus (InGaAlP) (λ = 670 nm) laser on the synovial membrane present in the knee joint in experimentally induced microcrystalline arthritis in male adult Wistar rats. The animals were divided into three experimental groups (n = 24): control (A), experimentally induced arthritis (B), experimentally induced arthritis+InGaAlP laser therapy (C). The laser treatment was made daily in the patellar region of the right knee after 48 h of the experimental induction. After 7, 14, and 21 days of therapy, the rats were euthanized and the right knees were removed and processed for histomorphometric, immunohistochemical, ultrastructural, and biochemical investigation of the synovium. The number of granulocytes on the 14th and 21st days was higher in B and lower in C and, lastly, in A. The number of fibroblasts on the 14th and 21st days was similar between A and C and below B. The number of blood vessels on the 21st day was higher in B than in the other groups. The positive number of cells for the TUNEL test was higher on the 14th and 21st days in B compared to the others. The percentage of tissue area occupied by birefringent collagen fibers was higher in B on the 21st day than in the others. The ultrastructure of cells showed fibroblast-like morphology in all groups and periods evaluated. The quantification of glycosaminoglycans did not present significant differences between the groups in all the experimental periods. The amount of hydroxyproline was higher in B compared to the other groups on the 14th and 21st days. The content of non-collagen proteins was higher in B on the 21st day in relation to the other groups. Quantification of TNF-α on the 21st day was higher in A and B than in C. For TGF-β on the 21st day, groups B and C presented similar and higher values than A. For MMP-13, groups A and B presented data similar to and above C. In relation to ADAMT-S4, on the 21st day, groups B and C presented data similar to and lower than A. InGaAlP-670 nm therapy reduced the inflammatory process and tissue injuries of the synovial membrane in comparison to the untreated group, indicating its potential utilization in clinical studies aiming in the recovery of acute arthritis in patients.

In Vitro Cytological Responses against Laser Photobiomodulation for Periodontal Regeneration

Periodontal disease is a chronic inflammatory disease caused by periodontal bacteria. Recently, periodontal phototherapy, treatment using various types of lasers, has attracted attention. Photobiomodulation, the biological effect of low-power laser irradiation, has been widely studied. Although many types of lasers are applied in periodontal phototherapy, molecular biological effects of laser irradiation on cells in periodontal tissues are unclear. Here, we have summarized the molecular biological effects of diode, Nd:YAG, Er:YAG, Er,Cr:YSGG, and CO₂ lasers irradiation on cells in periodontal tissues. Photobiomodulation by laser irradiation enhanced cell proliferation and calcification in osteoblasts with altering gene expression. Positive effects were observed in fibroblasts on the proliferation, migration, and secretion of chemokines/cytokines. Laser irradiation suppressed gene expression related to inflammation in osteoblasts, fibroblasts, human periodontal ligament cells (hPDLCs), and endothelial cells. Furthermore, recent studies have revealed that laser irradiation affects cell differentiation in hPDLCs and stem cells. Additionally, some studies have also investigated the effects of laser irradiation on endothelial cells, cementoblasts, epithelial cells, osteoclasts, and osteocytes. The appropriate irradiation power was different for each laser apparatus and targeted cells. Thus, through this review, we tried to shed light on basic research that would ultimately lead to clinical application of periodontal phototherapy in the future.

Interaction between Laser Light and Osteoblasts: Photobiomodulation as a Trend in the Management of Socket Bone Preservation-A Review

Simple Summary

Dental implants are becoming an accepted tool, and thousands of implants are placed every year by specialists and general practitioners. However, more than 10% of bone surgeries and related procedures can show healing complications as a consequence of infections, tissue damage, or inadequate blood supply. In particular, a deficient blood supply impacts on the optimal healing process because of altered oxygen delivery to cells in the wound and a decrease in their energy supply. Researchers showed how red and infrared light affects key cellular pathways by interacting with specific photoacceptors located within the cell, particularly in mitochondria. Low-level laser therapy or photobiomodulation (PBM), as the recent medical subject heading defines it, is based on a light–cell interaction, which modifies cell metabolism by increasing oxygen consumption and ATP production through mitochondria. Although not all aspects of this interconnection are completely described, many in vitro and in vivo studies showed the benefit of PBM in wound defect management. For instance, treatment of bone with PBM results in a greater amount of new-formed osteoblasts and matrix, an increase in collagen synthesis, and microvascular reestablishment. In our review, we highlight the osteoblast–light interaction, and the in vivo therapeutic tool of PBM for socket preservation is discussed.

Abstract

Bone defects are the main reason for aesthetic and functional disability, which negatively affect patient’s quality of life. Particularly, after tooth extraction, the bone of the alveolar process resorbs, limiting the optimal prosthetic implant placement. One of the major pathophysiological events in slowly- or non-healing tissues is a blood supply deficiency, followed by a significant decrease in cellular energy amount. The literature shows that photons at the red and infrared wavelengths can interact with specific photoacceptors located within the cell. Through this mechanism, photobiomodulation (PBM) can modify cellular metabolism, by increasing mitochondrial ATP production. Here, we present a review of the literature on the effect of PBM on bone healing, for the management of socket preservation. A search strategy was developed in line with the PRISMA statement. The PubMed and Scholar electronic databases were consulted to search for in vivo studies, with restrictions on the year (<50 years-old), language (English), bone socket preservation, and PBM. Following the search strategy, we identified 269 records, which became 14, after duplicates were removed and titles, abstract and inclusion-, exclusion-criteria were screened. Additional articles identified were 3. Therefore, 17 articles were included in the synthesis. We highlight the osteoblast–light interaction, and the in vivo therapeutic tool of PBM is discussed.

Effects of 660 nm and 810 nm Low-Power Diode Laser on Proliferation and Invasion of Oral Cancer Cells in Cell Culture Media

In the present study, the effects of 660 and 810 nm diode laser on the proliferation and invasion of cancer cells were investigated. Sixteen plates of oral cancer cells originated from tongue SCC were irradiated with diode laser at 660 nm (40 and 80 mW) and 810 nm (100 and 200 mW) with the energy density of 4 J cm^-2 . One plate received no irradiation (the control). Irradiation was performed at four times (0, 24, 72 and 168 h). Cell proliferation was measured by MTT assay. The Ki67 and vascular endothelial growth factor (VEGF) markers were examined by real-time polymerase chain reaction (RT-PCR). Cyclin D1, E-cadherin, β-catenin and matrix metalloproteinase-9 (MMP-9; flow cytometry) were also evaluated. Proliferation was lower in the irradiated groups. This result was significant for all groups at 24 h. The percentages of cyclin D1 and MMP-9 were higher in 810 nm groups, β-catenin and E-cadherin were higher in 660 nm groups, VEGF marker was significantly lower in 810 nm/200 mW group, and Ki67 marker has no difference between the groups. According to the results of this study, laser irradiation at 0 and 24 h resulted in a significant inhibitory effect on cell proliferation especially in 660 nm/80 mW and 810 nm/200 mW. Further studies are needed in this respect.

Safety and efficacy of photobiomodulation therapy in oncology: A systematic review

We performed a systematic review of the current literature addressing the safety and efficacy of photobiomodulation therapy (PBMT) in cancer patients. In this systematic review, the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines were used. In vitro, in vivo, and clinical studies, which investigated the effect of PBMT on cell proliferation/differentiation, tumor growth, recurrence rate, and/or overall survival were included. The Medline/PubMed, EMBASE, and Scopus databases were searched through April 2020. A total of 67 studies met the inclusion criteria with 43 in vitro, 15 in vivo, and 9 clinical studies identified. In vitro studies investigating the effect of PBMT on a diverse range of cancer cell lines demonstrated conflicting results. This could be due to the differences in used parameters and the frequency of PBM applications. In vivo studies and clinical trials with a follow‐up period demonstrated that PBMT is safe with regards to tumor growth and patient advantage in the prevention and treatment of specific cancer therapy‐related complications. Current human studies, supported by most animal studies, show safety with PBMT using currently recommended clinical parameters, including in Head & Neck cancer (HNC) in the area of PBMT exposure. A significant and growing literature indicates that PBMT is safe and effective, and may even offer a benefit in patient overall survival. Nevertheless, continuing research is indicated to improve understanding and provide further elucidation of remaining questions regarding PBM use in oncology.

Platelet rich fibrin versus ozone gel for periodontal regeneration in induced rats' intrabony three-wall periodontal defects

BACKGROUND

The question of whether platelet rich fibrin and ozone can enhance regeneration of periodontal defect was addressed.

MATERIALS AND METHODS

three-wall periodontal defects were surgically created in 30 rats involving mesial aspect of right mandibular first molar. Rats were randomly assigned into three groups: 1) Group I (Positive control group). 2) Group II (Ozone treated group) and 3) Group III (PRF treated group). Two weeks after surgery, five rats from each group were euthanized and the remaining was euthanized 4 weeks post surgery. The degree of periodontal regeneration was evaluated using light microscope and scanning electron microscope. Histomorphometric measurements and anti-PCNA immunohistochemical counting were statistically analyzed.

RESULTS

group I showed intense inflammatory reaction with mild new bone formation. In group II, partial regeneration was seen with moderate new woven bone formation in 2 weeks period. After 4 weeks, almost complete restoration of periodontium was seen. In group III, after 2 weeks, moderate lamellar bone formation was observed. In 4 weeks period, the periodontal regeneration was almost completed. Histomorphometric analysis showed a significant difference between group I and group II. The difference between group I and group III was significant in 2 weeks and highly significant after 4 weeks. That between group II and group III was nonsignificant in 2 weeks and significant in 4 weeks. Anti-PCNA analysis was nonsignificant between groups.

CONCLUSIONS

both Platelet rich fibrin and ozone can improve histological parameters associated with healing of experimental intrabony periodontal defects in rats with the former being superior.

Bone marrow coagulated and low-level laser therapy accelerate bone healing by enhancing angiogenesis, cell proliferation, osteoblast differentiation, and mineralization

The present study evaluated bone marrow aspirate (BMA) and low-level laser therapy (LLLT) on bone healing. It was created critical-size defects (CSD) of 5 mm diameter in rat calvaria of 64 rats. Animals were randomly divided into four groups: Control (blood clot), BMA (coagulated BMA), LLLT (laser irradiation and blood clot), and BMA/LLLT (laser irradiation and coagulated BMA). Euthanasia was performed at 15 or 30 days postoperative. Immunohistochemical reactions were performed to identify vascular endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA), runt-related transcription factor-2 (Runx2), bone morphogenetic protein-2 (BMP-2), osteocalcin (OCN), and osteopontin (OPN). The markers were quantified, and data were statistically analyzed. Groups BMA/LLLT and LLLT presented significantly higher VEGF expression than group control. Group BMA/LLLT presented a significantly higher expression of PCNA than all experimental groups. Groups BMA and BMA/LLLT presented significantly higher expression of BMP-2 than all experimental groups. Groups LLLT and BMA/LLLT presented significantly higher expression of OPN than groups control and BMA. Groups LLLT, BMA, and BMA/LLLT presented a significantly higher expression of OCN than group control. It can be concluded that the association of BMA and LLLT enhanced bone healing by improving expression of VEGF, PCNA, Runx2, BMP-2, OPN, and OCN.

Photo biostimulatory effect of low dose photodynamic therapy on human mesenchymal stem cells

BACKGROUND

Tissue engineering is one treatment to regenerate bone . Stem cell proliferation or differentiation can be stimulated by adjunctive approaches like photobiomodulation. Some studies suggested that, photodynamic therapy with low concentration of photosensitizers can stimulate cell differentiation as a photobiomodulation approach.

METHODS

Human bone marrow mesenchymal stem cell was isolated and then cultured in sterile medium. Two photosensitizer drugs as 5- aminolevulenic acid (1 mM) (5-ALA) and Methylene blue (1μM) (MB) were used in incubation culture media. In order to activate the photosensitizers, 630 and 660 nm wavelengths were irradiated with 1 J/cm2 energy density, respectively. Cell viability was assessed using MTT assay before and after laser irradiation, and also Alizarin red histologic test was used for calcium nodule formation.

RESULTS

performing the MTT test before irradiation showed that, the optimum concentrations were 1 mM for 5-ALA and 1μM for MB that were optimized. After laser irradiation, ALA group showed no osseous differentiation. In contrast, there was a significant calcium nodule formation in MB group compared with the control one.

CONCLUSIONS

Photodynamic therapy with low photosensitizer concentration and low doses of laser energy density may improve osteogenic differentiation. Accordingly, MB had stimulatory effect on bone marrow derived mesenchymal stem cells. However, 5-ALA did not show this effect.

Laser and LED photobiomodulation effects in osteogenic or regular medium on rat calvaria osteoblasts obtained by newly forming bone technique

The purposes of this study are to evaluate the effects of photobiomodulation (PBM) with laser and LED on rat calvaria osteoblasts (rGO lineage), cultured in osteogenic (OST) or regular (REG) medium, after induction of a quiescent state and to test if PBM is capable of osteogenic induction and if there is a sum of effects when combining OST medium with PBM. Before irradiation, the cells were put in a quiescent state (1% FBS) 24 h, when red (AlGaInP-660 nm) and infrared laser (GaAlAs-808 nm) and LED (637 ± 15 nm) were applied. The groups were as follows: red laser (RL3-5 J/cm², 3 s and RL5-8.3 J/cm², 5 s, 1.66 W/cm²); infrared laser (IrL3-5 J/cm², 3 s and IrL5-8.3 J/cm², 5 s); LED (LED3-3 s and LED5-5 s, 0.02 J/cm², 0.885 W/cm²); positive (C+, 10% FBS) and negative control (C-, 1% FBS). For alkaline phosphatase (ALP) and mineralization assays, the cells were cultured in REG (DMEM 10% FBS) and OST medium (DMEM 10% FBS, 50 μg/mL ascorbic acid, 10 mM β-glycerophosphate). Statistical analysis was performed using ANOVA and Tukey's tests (p < 0.05). RL5 and LED5 increased proliferation, in vitro wound closure, ALP, and mineralization in rGO cells (p < 0.05). PBM with red laser and LED induced mineralization by itself, without osteogenic medium, not observed for infrared laser (p < 0.05). A sum of effects was observed in osteogenic medium and PBM by infrared, red laser, and LED (5 s). Red laser and LED increased proliferation, migration, and secretory phases in rGO cells in a dose-dependent manner. PBM with red laser and LED promotes osteogenic induction by itself. PBM with infrared laser and osteogenic medium potentializes mineralization.

Raman spectroscopic study of the effect of the use of laser/LED phototherapy on the repair of complete tibial fracture treated with internal rigid fixation

This study aimed to assess the repair of complete surgical tibial fractures fixed with internal rigid fixation (IRF) associated or not to the use of mineral trioxide aggregate (MTA) cement and treated or not with laser (λ = 780 nm, infrared) or LED (λ = 850 ± 10 nm, infrared) lights, 142.8 J/cm² per treatment, by means of Raman spectroscopy. Open surgical tibial fractures were created on 18 rabbits (6 groups of 3 animals per group, ∼8 months old) and fractures were fixed with IRF. Three groups were grafted with MTA. The groups of IRF and IRF + MTA that received laser or LED were irradiated every other day during 15 days. Animals were sacrificed after 30 days, being the tibia surgically removed. Raman spectra were collected via the probe at the defect site in five points, resulting in 15 spectra per group (90 spectra in the dataset). Spectra were collected at the same day to avoid changes in laser power and experimental setup. The ANOVA general linear model showed that the laser irradiation of tibial bone fractures fixed with IRF and grafted with MTA had significant influence in the content of phosphate (peak ∼960 cm^-1) and carbonated (peak ∼1,070 cm^-1) hydroxyapatites as well as collagen (peak 1,452 cm^-1). Also, peaks of calcium carbonate (1,088 cm^-1) were found in the groups grafted with MTA. Based on the Raman spectroscopic data collected in this study, MTA has been shown to improve the repair of complete tibial fractures treated with IRF, with an evident increase of collagen matrix synthesis, and development of a scaffold of hydroxyapatite-like calcium carbonate with subsequent deposition of phosphate hydroxyapatite.

Effects of photobiomodulation in the treatment of fractures: a systematic review and meta-analysis of randomized clinical trials

Several therapeutic strategies have been proposed to optimize the conventional treatment of fractures. Photobiomodulation (PBM) appears to help reduce pain and control inflammation, and it also accelerates bone repair. This systematic review aimed to evaluate the effectiveness and safety of PBM with low-level laser therapy (LLLT) in the bone fracture healing process. We included randomized controlled trials (RCTs) comparing the effects of PBM with those of any other intervention in adults with lower or upper limb bone fractures. The primary outcomes investigated were pain reduction, radiographic healing, and adverse events. The searches were conducted in October 2018. Two RCTs were included that compared PBM to the placebo. A meta-analysis showed significant difference in favor of PBM for pain reduction (MD 1.19, 95% CI [0.61 to 1.77], 106 participants, two RCTs), but this difference was not clinically significant. One RCT (50 participants) showed a clinical and statistical improvement in physical function (MD - 14.60, 95% CI [- 21.39 to - 7.81]) and no difference in radiographic healing, regarding absence of fracture line (RR 1.00, 95% CI [0.93 to 1.08]) and visible bone callus (RR 0.33, 95% CI [0.01 to 7.81]). The certainty of evidence was classified as low to very low. Based on the evidence of low to very low certainty, PBM seems to be associated with the improvement of pain and function. Therefore, new RCTs are required that meet the recommendations of CONSORT to prove the effectiveness and safety of this intervention and support its recommendation in clinical practice.

The effect of low-level laser radiation and doxycycline on the levels of osteoprotegerin and receptor activator of nuclear factor kappa-B ligand

The present in vitro study was conducted to investigate the effect of low-level laser (LLL) radiation and doxycycline on the levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) derived from MG-63 osteosarcoma cell line. MG-63 cells were divided into four groups. In the first group, 2 mg/mL of doxycycline was injected into the cell culture medium. Diode laser (810 nm, 100 mw, 75 s) was radiated to the culture medium of the second group. The third group received both doxycycline and laser radiation. In the fourth group (control), the culture medium was replaced daily, similar to the above three groups. Mentioned interventions were performed once a day for 4 consecutive days. Then, on the sixth day, the levels of OPG and RANKL mediators were measured using real-time polymerase chain reaction by isolating the cells from the samples. OPG expression had the highest to lowest levels in the laser + doxycycline, doxycycline, laser, and control groups, respectively. The level of OPG was significantly different between all the study groups (p < 0.05) except in the doxycycline + laser and doxycycline groups (p = 0.061). The highest to lowest levels of RANKL was observed in the doxycycline, laser + doxycycline, control, and laser groups, respectively. The RANKL expression was not significantly different between all the study groups (p > 0.05). The results of this study revealed that LLL and doxycycline reduced the RANKL/OPG ratio derived from the MG-63 osteosarcoma cell line, which may result in the diminished activity of osteoclasts and osteoclastogenesis.

Photobiomodulation effects on osteogenic differentiation of adipose-derived stem cells

Increasing interest has been observed in the use of photobiomodulation (PBM) to enhance the proliferation of stem cells and induce their differentiation. The effects of PBM at two different wavelengths (635 and 809 nm) with three different energy densities (0.5, 1 and 2 J/cm²) on the osteogenic differentiation of adipose-derived stem cells (ADSC) were investigated. Cell viability and proliferation were evaluated by MTT and Alamar Blue assays. Osteoblast differentiation were assessed by alkaline phosphatase (ALP) activity, Alizarin red staining and reverse-transcription polymerase chain reaction (RT-PCR) for the expression of collagen type I (COL1A), ALP and osteocalcin. 635 nm and 809 nm laser irradiation had no effect on the cell viability on days 7 and 14, except for 0.5 J/cm² group at 14th day after 635 nm irradiation (p < 0.05). Cell proliferation was not changed significantly. Mineralization was increased significantly in 809 nm laser groups but no enhancement was detected in the osteogenic differentiation by ALP activity and gene expression results. In 0.5 and 1 J/cm² groups, ALP and COL1A expressions were down regulated at day 7 after 809 nm laser exposure. These results suggest that PBM may alter osteogenic differentiation of ADSC and increase mineralization but further investigation is needed to define adequate parameters.

Osteogenic Potential of Bovine Bone Graft in Combination with Laser Photobiomodulation: An Ex Vivo Demonstrative Study in Wistar Rats by Cross-Linked Studies Based on Synchrotron Microtomography and Histology

BACKGROUND

Alveolar bone defects are usually the main concern when planning implant treatments for the appropriate oral rehabilitation of patients. To improve local conditions and achieve implant treatments, there are several methods used for increasing bone volume, among which one of the most successful, versatile, and effective is considered to be guided bone regeneration. The aim of this demonstrative study was to propose an innovative analysis protocol for the evaluation of the effect of photobiomodulation on the bone regeneration process, using rat calvarial defects of 5 mm in diameter, filled with xenograft, covered with collagen membrane, and then exposed to laser radiation.

METHODS

The animals were sacrificed at different points in time (i.e., after 14, 21, and 30 days). Samples of identical dimensions were harvested in order to compare the results obtained after different periods of healing. The analysis was performed by cross-linking the information obtained using histology and high-resolution synchrotron-based tomography on the same samples. A comparison was made with both the negative control (NC) group (with a bone defect which was left for spontaneous healing), and the positive control (PC) group (in which the bone defects were filled with xenografts and collagen membrane without receiving laser treatment).

RESULTS

We demonstrated that using photobiomodulation provides a better healing effect than when receiving only the support of the biomaterial. This effect has been evident for short times treatments, i.e., during the first 14 days after surgery.

CONCLUSION

The proposed analysis protocol was effective in detecting the presence of higher quantities of bone volumes under remodeling after photobiomodulation with respect to the exclusive bone regeneration guided by the xenograft.

Percutaneous Exposures of volunteers to polychromatic light (480-3400 nm) trigger systemic mechanism of the human myeloma cells growth delay without any effect on bortezomib cytotoxicity in vitro

Background and aim

Polychromatic light is actively used in medicine. However, its oncological safety and effect against cytotoxic therapy remains poorly studied. Multiple myeloma (MM) develops in the bone marrow and therefore malignant plasma cells are inaccessible to direct exposure to light. The aim of our work was to study the influence of polychromatic visible and infra-red light (pVIS + pIR) on growth and sensitivity of the myeloma cells to the cytotoxic effect of drug bortezomib (BTZ) through systemic mechanism.

Materials and methods

We explored the effect of volunteers blood sera after their 4-daily irradiations with pVIS + pIR light (480-3400 nm) on growth and viability of the human myeloma RPMI 8226 cells in the presence of BTZ at its application in 2 modes: short-term (1 h, 300 nM) and long-term ( 96 h, 5 nM). Viability and proliferative activity of cells was evaluated by MTT assay.

Results

It was found that photomodified blood sera delayed growth of myeloma RPMI 8226 cells (by 25 % in 48 h and 23 % in 96 h) but had no effect on spontaneous and mitogen-induced proliferation of autologous peripheral blood T- and B-lymphocytes. We also revealed that pVIS + pIR did not change RPMI 8226 cells sensitivity to BTZ.

Conclusion

The results suggest the systemic mechanism of polychromatic light and argue in favor of its oncological safety during/after BTZ therapy of MM patients without effect on the drug cytotoxicity.

Bioglass/PLGA associated to photobiomodulation: effects on the healing process in an experimental model of calvarial bone defect

Bioactive glasses (BG) are known for their ability to bond to bone tissue. However, in critical situations, even the osteogenic properties of BG may be not enough to induce bone consolidation. Thus, the enrichment of BG with polymers such as Poly (D, L-lactic-co-glycolic) acid (PLGA) and associated to photobiomodulation (PBM) may be a promising strategy to promote bone tissue healing. The aim of the present study was to investigate the in vivo performance of PLGA supplemented BG, associated to PBM therapy, using an experimental model of cranial bone defect in rats. Rats were distributed in 4 different groups (Bioglass, Bioglass/PBM, Bioglas/PLGA and BG/PLGA/PBM). After the surgical procedure to induce cranial bone defects, the pre-set samples were implanted and PBM treatment (low-level laser therapy) started (808 nm, 100 mW, 30 J/cm²). After 2 and 6 weeks, animals were euthanized, and the samples were retrieved for the histopathological, histomorphometric, picrosirius red staining and immunohistochemistry analysis. At 2 weeks post-surgery, it was observed granulation tissue and areas of newly formed bone in all experimental groups. At 6 weeks post-surgery, BG/PLGA (with or without PBM) more mature tissue around the biomaterial particles. Furthermore, there was a higher deposition of collagen for BG/PLGA in comparison with BG/PLGA/PBM, at second time-point. Histomorphometric analysis demonstrated higher values of BM.V/TV for BG compared to BG/PLGA (2 weeks post-surgery) and N.Ob/T.Ar for BG/PLGA compared to BG and BG/PBM (6 weeks post-surgery). This current study concluded that the use of BG/PLGA composites, associated or not to PBM, is a promising strategy for bone tissue engineering.

Quantitative assessment of rat bone regeneration using complex master-slave optical coherence tomography

Background

The need for hard and soft tissues in oral implantology determined the development of methods and techniques to increase bone volume and their quality with different alternative materials used as substituents of patient's natural bone. In addition, laser radiation can be used to accelerate the repair of fractures and to produce an increased volume of formed callus, as well as an increased bone mineral density.

Methods

The aim of this work is to evaluate the capability of an in-house developed multimodal complex master slave (CMS) enhanced swept source (SS) optical coherence tomography (OCT) imaging instrument to analyze the increase in the quantity and the improvement of the quality of newly-formed bone using low level laser therapy (LLLT). Bone formation is quantitatively assessed in 5 mm cylindrical defects made in the calvaria part of the skull of living rats. Samples are divided in three study groups: A, a negative control group, for which the natural healing process of the defect is investigated; B, a positive control group, for which bovine graft is used to stimulate bone formation, and C, a study group, in which bovine graft is added to the created defects and LLLT is applied throughout the entire healing period. The animals are sacrificed after 14, 21, and 30 days, and the samples are imaged using the multimodal CMS/SS-OCT instrument.

Results

The method allows for the simultaneous monitoring of the bone tissue via two perpendicular cross-sections and nine en-face images taken at adjustable depths into the sample. A global image with course axial resolution allows for the positioning of the field-of-view of the system on the area of interest on the tissue. The quantitative assessment of the process of bone formation is completed using the differences in brightness between the native bone, the artificial bone graft, and the newly-formed bone.

Conclusions

Group C is demonstrated to have a higher volume of newly-formed bone than Group B, which is better from this point of view than Group A. By analyzing the evolution of this volume of new bone in time, the most significant difference was after 21 days, therefore approximately after two thirds of the total time interval analyzed. After 30 days, the volumes of bone tend to move closer, as they begin to fill the available gap. The study demonstrates that OCT can assess quantitatively the positive impact of LLLT on bone regeneration.

Effects of Different Parameters of Diode Laser on Acceleration of Orthodontic Tooth Movement and Its Effect on Relapse: An Experimental Animal Study

AIM:

Recent studies have demonstrated that low-level laser therapy (LLLT) can accelerate orthodontic tooth movement. However, there is still controversy about the optimum parameters that can cause acceleration. The present study was designed to examine two different doses of LLLT in the acceleration of orthodontic tooth movement and their effect on relapse.

METHODS:

An orthodontic appliance was designed to induce tooth movement on lower incisors of rabbits. The in-al-as diode laser was used to radiate different groups of rabbits according to a specific protocol. The amount of tooth movement was measured for 21 days, and then the orthodontic appliance was removed, and the relapse was measured till day 28.

RESULTS:

The amount of tooth movement was significantly greater in the group with irradiation of low dose in comparison with the high dose group and the control group. The relapse was greatest in the group of low dose irradiation and least in the control group.

CONCLUSION:

The findings suggest that LLLT with a low dose accelerate the orthodontic tooth movement while LLLT with a high dose was not able to have the same effect. LLLT had a reverse effect on relapse tendency; an increase in the relapse tendency was seen with low dose irradiation.

Photobiomodulation with single and combination laser wavelengths on bone marrow mesenchymal stem cells: proliferation and differentiation to bone or cartilage

Tissue engineering aims to take advantage of the ability of undifferentiated stem cells to differentiate into multiple cell types to repair damaged tissue. Photobiomodulation uses either lasers or light-emitting diodes to promote stem cell proliferation and differentiation. The present study aimed to investigate single and dual combinations of laser wavelengths on mesenchymal stem cells (MSCs). MSCs were derived from rabbit iliac bone marrow. One control and eight laser irradiated groups were designated as Infrared (IR, 810 nm), Red (R, 660 nm), Green (G, 532 nm), Blue (B, 485 nm), IR-R, IR-B, R-G, and B-G. Irradiation was repeated daily for 21 days and cell proliferation, osseous, or cartilaginous differentiation was then measured. RT-PCR biomarkers were SOX9, aggrecan, COL 2, and COL 10 expression for cartilage and ALP, COL 1, and osteocalcin expression for bone. Cellular proliferation was increased in all irradiated groups except G. All cartilage markers were significantly increased by IR and IR-B except COL 10 which was suppressed by IR-B combination. ALP expression was highest in R and IR groups during osseous differentiation. ALP was decreased by combinations of IR with B and with R, and also by G alone. R and B-G groups showed stimulated COL 1 expression; however, COL 1 was suppressed in IR-B, IR-R, and G groups. IR significantly increased osteocalcin expression, but in B, B-G, and G groups it was reduced. Cartilage differentiation was stimulated by IR and IR-B laser irradiation. The effects of single or combined laser irradiation were not clear-cut on osseous differentiation. Stimulatory effects on osteogenesis were seen for R and IR lasers, while G laser had inhibitory effects.

A Comparative Study Between the Effectiveness of 980 nm Photobiomodulation Delivered by Hand-Piece With Gaussian vs. Flat-Top Profiles on Osteoblasts Maturation

Photobiomodulation (PBM) is a clinically accepted tool in regenerative medicine and dentistry to improve tissue healing and repair and to restore the functional disability. The current in vitro study aimed to investigate the photobiomodulatory effects of 980 nm wavelength (the real energy at the target: ~0.9 W, ~0.9 W/cm², 60 s, ~55 J/cm² and a single energy ~55 J in CW) on MC3T3-E1 pre-osteoblast, delivered with flattop profile in comparison to the standard profile. The laser groupings and their associated energies were: Group 1 - once per week (total energy 110 J); Group 2 - three times per week (alternate day) (total energy 330 J); Group 3 - five times per week (total energy 550 J). The metabolic activity and the osteoblasts maturation were analyzed by alkaline phosphatase assay, alizarin red S histological staining, immunoblot and/or double immunolabeling analysis for Bcl2, Bax, Runx-2, Osx, Dlx5, osteocalcin, and collagen Type 1. Our data, for the first time, prove that laser irradiation of 980 nm wavelength with flat-top beam profile delivery system, compared to standard-Gaussian profile, has improved photobiomodulatory efficacy on pre-osteoblastic cells differentiation. Mechanistically, the irradiation enhances the pre-osteoblast differentiation through activation of Wnt signaling and activation of Smads 2/3-βcatenin pathway.

Combined effect of recombinant human bone morphogenetic protein-2 and low level laser irradiation on bisphosphonate-treated osteoblasts

Objectives

The purpose of this study was to evaluate the synergic effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) and low-level laser therapy (LLLT) on bisphosphonate-treated osteoblasts.

Materials and Methods

Human fetal osteoblast cells (hFOB 1.19) were cultured with 100 µM alendronate. Low-level Ga-Al-As laser alone or with 100 ng/mL rhBMP-2 was then applied. Cell viability was measured with MTT assay. The expression levels of receptor activator of nuclear factor kappa-B ligand (RANKL), macrophage colony-stimulating factor (M-CSF), and osteoprotegerin (OPG) were analyzed for osteoblastic activity inducing osteoclastic activity. Collagen type and transforming growth factor beta-1 were also evaluated for bone matrix formation.

Results

The results showed that rhBMP-2 and LLLT had a synergic effect on alendronate-treated osteoblasts for enhancing osteoblastic activity and bone matrix formation. Between rhBMP-2 and LLLT, rhBMP-2 exhibited a greater effect, but did not show a significant difference.

Conclusion

rhBMP-2 and LLLT have synergic effects on bisphosphonate-treated osteoblasts through enhancement of osteoblastic activity and bone formation activity.

Combined Treatment with Low-Level Laser and rhBMP-2 Promotes Differentiation and Mineralization of Osteoblastic Cells under Hypoxic Stress

Background

The aim of this study was to evaluate the combined effect of low-level laser treatment (LLLT) and recombinant human bone morphological protein-2 (rhBMP-2) applied to hypoxic-cultured MC3T3-E1 osteoblastic cells and to determine possible signaling pathways underlying differentiation and mineralization of osteoblasts under hypoxia.

Methods

MC3T3-E1 cells were cultured under 1% oxygen tension for 72 h. Cell cultures were divided into four groups: normoxia control, low-level laser (LLL) alone, rhBMP-2 combined with LLLT, and rhBMP-2 under hypoxia. Laser irradiation was applied at 0, 24, and 48 h. Cells were treated with rhBMP-2 at 50 ng/mL. Alkaline phosphatase activity was measured at 3, 7, and 14 days to evaluate osteoblastic differentiation. Cell mineralization was determined with Alizarin red S staining at 7 and 14 days. Western blot assays were performed to evaluate whether p38/protein kinase D (PKD) signaling was involved.

Results

The results indicate that LLLT and rhBMP-2 synergistically increased alkaline phosphatase (ALP) activity and mineralization. Western blot analyses showed that expression of type I collagen, runt-related transcription factor 2 (RUNX2), and Osterix (Osx), increased and expression of hypoxia-inducible factor 1-alpha (HIF-1α), decreased more in the LLLT and rhBMP-2 combined group than in the rhBMP-2 or LLL alone groups. Moreover, LLLT and rhBMP-2 stimulated p38 phosphorylation and rhBMP-2 and LLLT increased Prkd1 phosphorylation.

Conclusion

Combined treatment with rhBMP-2 and LLL induced differentiation and mineralization of hypoxic-cultured MC3T3-E1 osteoblasts by activating p38/PKD signaling in vitro.

Influence of low-level laser irradiation on osteocalcin protein and gene expression in bone tissue1

PURPOSE

To evaluate osteocalcin gene and protein expression in vitro and in an in vivo model of ostectomy.

METHODS

Twenty Wistar rats were assigned into two groups A (n=10, laser) and B (n=10, control). Ostectomy was performed in the femur diaphysis; the twenty fragments removed, composed in vitro groups named as in vivo (A and B) and cultivated in CO2 atmosphere for thirteen days. Low-level laser irradiation was performed in groups A (in vivo and in vitro) by an GaAlAs device (λ=808 nm, dose of 2J/cm2, power of 200mW, power density of 0.2W/cm2, total energy of 1.25J, spot diameter of 0.02mm) for 5 seconds, at one point, daily. It was performed immunocytochemistry assays in vivo and in vitro groups. In vitro groups were also submitted to RNA extraction, cDNA synthesis and gene expression by quantitative PCR. Statistical analysis was realized with p<0.05.

RESULTS

Immunocytochemistry scores showed no significant differences between control and laser groups either in vivo and in vitro. Gene expression also showed no statistical differences.

CONCLUSION

Low-level laser irradiation did not alter osteocalcin protein and gene expression in vivo and in vitro in the studied period but it may have been expressed them in an earlier period.