Bone substitutes and photobiomodulation in bone regeneration: A systematic review in animal experimental studies.

In general, bone fractures are able of healing by itself. However, in critical situations such as large bone defects, poor blood supply or even infections, the biological capacity of repair can be impaired, resulting in a delay of the consolidation process or even in non-union fractures. Thus, technologies able of improving the process of bone regeneration are of high demand. In this context, ceramic biomaterials-based bone substitutes and photobiomodulation (PBM) have been emerging as promising alternatives. Thus, the present study performed a systematic review targeting to analyze studies in the literature which investigated the effects of the association of ceramic based bone substitutes and PBM in the process of bone healing using animal models of bone defects. The search was conducted from March and April of 2019 in PubMed, Web of Science and Scopus databases. After the eligibility analyses, 16 studies were included in this review. The results showed that the most common material used was hydroxyapatite (HA) followed by Biosilicate associated with infrared PBM. Furthermore, 75% of the studies demonstrated positive effects to stimulate bone regeneration from association of ceramic biomaterials and PBM. All studies used low-level laser therapy (LLLT) device and the most studies used LLLT infrared. The evidence synthesis was moderate for all experimental studies for the variable histological analysis demonstrating the efficacy of techniques on the process of bone repair stimulation. In conclusion, this review demonstrates that the association of ceramic biomaterials and PBM presented positive effects for bone repair in experimental models of bone defects.

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.

Low-level laser therapy modulates demyelination in mice.

There are no effective therapies for remyelination. Low-level laser therapy (LLLT) has been found advantageous in neurogenesis promotion, cell death prevention, and modulation of inflammation in central and peripheral nervous system models. The purpose of this study was to analyse LLLT effects on cuprizone-induced demyelination. Mice were randomly distributed into three groups: Control Laser (CTL), Cuprizone (CPZ), and Cuprizone Laser (CPZL). Mice from CPZ and CPZL groups were exposed to a 0.2% cuprizone oral diet for four complete weeks. Six sessions of transcranial laser irradiation were applied on three consecutive days, during the third and fourth weeks, with parameters of 36 J/cm2, 50 mW, 0.028 cm2 spot area, continuous wave, 1 J, 20 s, 1.78 W/cm2 in a single point equidistant between the eyes and ears of CTL and CPZL mice. Motor coordination was assessed by the rotarod test. Twenty-four hours after the last laser session, all animals were euthanized, and brains were extracted. Serum was obtained for lactate dehydrogenase toxicity testing. Histomorphological analyses consisted of Luxol Fast Blue staining and immunohistochemistry. The results showed that laser-treated animals presented motor performance improvement, attenuation of demyelination, increased number of oligodendrocyte precursor cells, modulated microglial and astrocytes activation, and a milder toxicity by cuprizone. Although further studies are required, it is suggested that LLLT represents a feasible therapy for demyelinating diseases.

Low-level laser therapy associated to a resistance training protocol on bone tissue in diabetic rats.

OBJECTIVE: The present study aimed to evaluate the in vivo response of a resistance training and low-level laser therapy (LLLT) on tibias and femurs of rats with diabetes mellitus (DM). MATERIALS AND METHODS: Forty male Wistar rats were randomly distributed into four experimental groups: control group (CG), diabetic group (DG), diabetic trained group (TG) and diabetic trained and laser irradiated group (TLG). DM was induced by streptozotocin (STZ) and after two weeks laser and resistance training started, performed for 24 sessions, during eight weeks. At the end of the experiment, animals were euthanized and tibias and femurs were removed for analysis. Histological, histomorphometrical, immunohistochemistry and mechanical analyses were performed. RESULTS: Trained groups, with or without laser irradiation, showed increased cortical area, bone density and biomechanical properties. The immunohistochemical analysis revealed that TG and TLG demonstrated an increased RUNX2 expression. RANK-L immunoexpression was similar for all experimental groups. CONCLUSION: In conclusion, it can be suggested that the resistance exercise program stimulated bone metabolism, culminating in increased cortical tibial area, bone mineral content, bone mineral density and biomechanical properties. Furthermore, the association of physical exercises and LLLT produced higher values for bone mineral content and stiffness. Consequently, these data highlight the potential of physical exercise in the management of bone loss due to DM and the possible extra osteogenic stimulus offered by lasertherapy. Further long-term studies should be carried out to provide additional information.

Low-level laser therapy associated to a resistance training protocol on bone tissue in diabetic rats

ABSTRACT Objective The present study aimed to evaluate the in vivo response of a resistance training and low-level laser therapy (LLLT) on tibias and femurs of rats with diabetes mellitus (DM). Materials and methods Forty male Wistar rats were randomly distributed into four experimental groups: control group (CG), diabetic group (DG), diabetic trained group (TG) and diabetic trained and laser irradiated group (TLG). DM was induced by streptozotocin (STZ) and after two weeks laser and resistance training started, performed for 24 sessions, during eight weeks. At the end of the experiment, animals were euthanized and tibias and femurs were removed for analysis. Histological, histomorphometrical, immunohistochemistry and mechanical analyses were performed. Results Trained groups, with or without laser irradiation, showed increased cortical area, bone density and biomechanical properties. The immunohistochemical analysis revealed that TG and TLG demonstrated an increased RUNX2 expression. RANK-L immunoexpression was similar for all experimental groups. Conclusion In conclusion, it can be suggested that the resistance exercise program stimulated bone metabolism, culminating in increased cortical tibial area, bone mineral content, bone mineral density and biomechanical properties. Furthermore, the association of physical exercises and LLLT produced higher values for bone mineral content and stiffness. Consequently, these data highlight the potential of physical exercise in the management of bone loss due to DM and the possible extra osteogenic stimulus offered by lasertherapy. Further long-term studies should be carried out to provide additional information.

Low level laser therapy accelerates bone healing in spinal cord injured rats.

Bone loss occurs rapidly and consistently after the occurrence of a spinal cord injury (SCI), leading to a decrease in bone mineral density (BMD) and a higher risk of fractures. In this context, the stimulatory effects of low level laser therapy (LLLT) also known as photobiomodulation (PBM) have been highlighted, mainly due to its osteogenic potential. The aim of the present study was to evaluate the effects of LLLT on bone healing using an experimental model of tibial bone defect in SCI rats. Twenty-four female Wistar rats were randomly divided into 3 groups: Sham group (SG), SCI control group (SC) and SCI laser treated group (SL). Two weeks after the induction of the SCI, animals were submitted to surgery to induce a tibial bone defect. Treatment was performed 3days a week, for 2weeks, at a single point over the area of the injury, using an 808nm laser (30mW, 100J/cm(2); 0.028cm(2), 1.7W/cm², 2.8J). The results of the histological and morphometric evaluation demonstrated that the SL group showed a larger amount of newly formed bone compared to the SC group. Moreover, a significant immunoexpression of runt-related transcription factor 2 (RUNX2) was observed in the SL group. There was no statistical difference in the biomechanical evaluation. In conclusion, the results suggest that LLLT accelerated the process of bone repair in rats with complete SCI.

Effects of phototherapy on cartilage structure and inflammatory markers in an experimental model of osteoarthritis.

The aim of this study was to evaluate the effects of laser phototherapy on the degenerative modifications on the articular cartilage after the anterior cruciate ligament transection (ACLT) in the knee of rats. Eighty male rats (Wistar) were distributed into four groups: intact control group (IG), injured control group (CG), injured laser treated group at 10 J/cm(2) (L10), and injured laser treated group at 50 J/cm(2) (L50). Animals were distributed into two subgroups, sacrificed in 5 and 8 weeks postsurgery. The ACLT was used to induce knee osteoarthritis in rats. After 2 weeks postsurgery, laser phototherapy initiated and it was performed for 15 and 30 sessions. The histological findings revealed that laser irradiation, especially at 10 J/cm(2), modulated the progression of the degenerative process, showing a better cartilage structure and lower number of condrocytes compared to the other groups. Laser phototherapy was not able to decrease the degenerative process measured by Mankin score and prevent the increase of cartilage thickness related to the degenerative process. Moreover, it did not have any effect in the biomodulation of the expression of markers IL1ß, tumor necrosis factor-α, and metalloprotein-13. Furthermore, laser irradiated animals, at 50 J/cm(2) showed a lower amount of collagen type 1.

Avaliação funcional da disfunção temporomandibular após bioestimulação associado à cinesioterapia / Functional evaluation of temporomandibular joint disorders after bioestimulation combined with kinesiotherapy

A disfunção temporomandibular (DTM) é altamente debilitantee causa alteração na realização de algumas funções importantescomo mastigar alimentos ou falar adequadamente. Esta disfunçãogeralmente segue uma trajetória de eventos progressivos, podendodesencadear uma condição articular degenerativa. Diante disso, otratamento fisioterapêutico se destaca, por ser um tratamento nãomedicamentoso e não invasivo. Há uma escassez de artigos na literaturasobre a utilização de técnicas cinesioterapêuticas associadascom aplicação de laser de baixa intensidade. Diante deste contexto,o presente estudo teve como objetivo verificar o quadro clínico depacientes portadores de DTM, após intervenção fisioterapêutica.Cinco pacientes receberam tratamento fisioterapêutico, associandotécnicas cinesioterapêuticas e aplicação de laser de baixa intensidade.Foram realizadas três sessões semanalmente, durante dois meses. Paraverificar o quadro clínico, foi realizada avaliação da amplitude demovimento e aplicação dos questionários: questionário de Fonseca,índice de disfunção clínica craniomandibular, índice temporomandibulare o SF36. Através dos resultados deste estudo, a associação dasduas técnicas de tratamento demonstrou um aumento da amplitudede movimento articular e melhora nos escores de funcionalidade,correlacionados com a melhora importante dos aspectos sociais eemocionais. Assim, este é um importante indicador para o surgimentode novos estudos que enfatizem esta associação de técnicas.

The temporomandibular disorder (TMD) is a debilitating diseasethat causes changes in some important functions such as to chewfood or speak properly. This disorder usually develops a progressivetrajectory of events, which can lead to a degenerative joint disease.Therefore, physical therapy stands out for being a non-medicationand noninvasive treatment. There is little articles in the literatureconcerning the use of kinesiotherapy techniques associated withlow level laser. This study aimed to verify the clinical picture of patientswith TMD, after physical therapy intervention. Five patientsunderwent physical therapy combining kinesiotherapy and lowlevel laser application. Three sessions were held weekly during twomonths. In order to verify clinical current status, we carried out anevaluation of range of motion and used the following questionnaires:Fonseca questionnaire, Clinical Craniomandibular dysfunctionIndex, Temporomandibular Index and SF36. From the results ofthis study we observed that the combination of the two treatmenttechniques showed an increase in range of motion and improvementin functional scores, correlated with significant improvement ofsocial and emotional aspects. Thus, new studies emphasizing thecombination of the two techniques should be conducted.