Uso do laser de baixa potência para o tratamento de parestesia: uma revisão de literatura / Use of low-level laser to treat paresthesia: a literature review

Introdução: A parestesia é uma neuropatia que afeta a função sensorial. O Laser de Baixa Potência (LBP), por sua vez, apresenta propriedades analgésicas, bioestimuladoras e reparadoras. Objetivo: Realizar um levantamento na literatura científica sobre os aspectos gerais e benefícios do LBP no manejo terapêutico da parestesia, além de identificar a classificação e métodos de obtenção do diagnóstico desta condição. Materiais e Métodos: Tratou-se de uma revisão narrativa da literatura através da busca nas plataformas PubMed, SciELO, LILACS e Google Schoolar. Após o cruzamento dos descritores com os operadores booleanos e aplicação dos critérios de inclusão/exclusão, 26 estudos foram incluídos. Resultados: A parestesia pode ser classificada em neuropraxia, axonotmese e neurotmese, subdivididas em Grau I ao V. Seu diagnóstico pode ser executado através de testes subjetivos e objetivos. O LBP compreende em um dispositivo tecnológico com efeitos analgésico, anti-inflamatório e fotobiomodulador, que estimula o reparo neural. Os estudos mostram que a dosimetria nos comprimentos de onda vermelho e infravermelho, aplicação intra e extra oral, e com mais de uma sessão semanal exerce efeito modulatório positivo do reparo neural, com retorno progressivo da atividade sensitiva. Além disso, os estudos trazem uma ampla variação no número de pontos de aplicação, bem como no tempo de irradiação e quantidade de sessões, em virtude da extensão e tempo de diagnóstico da parestesia. Considerações finais: Apesar da alta complexidade da parestesia, o LBP exerce efeitos benéficos através do retorno da sensibilidade parcial ou total, além de ser um dispositivo bem tolerado pelo organismo e minimamente invasivo.

Introduction: Paresthesia is a neuropathy that affects sensory function. The Low-Level Laser (LLL), in turn, has analgesic, biostimulating and reparative properties. Purpose: Carry out a survey at the scientific literature on the general aspects and benefits of LLL in the therapeutic management of paresthesia in addition to identifying the classification and methods for obtaining a diagnosis of this condition. Materials and Methods: It was a narrative literature review through search in platforms PubMed, SciELO, LILACS and Google Schoolar. After crossing the descriptors with boolean operators and applying the inclusion/exclusion criteria, 26 articles were included in this study. Results: Paresthesia can be classified into neuropraxia, axonotmesis and neurotmesis, subdivided into Grades I to V. Its diagnostic can be carried out through subjective and objective tests. The LLL consists in a technological device with analgesic, anti-inflammatory and photobiomodulatory effects, which stimulates neural repair. Studies show that LLL in dosimetry at red and infrared wavelengths with intra and extra oral application and with more than one-week use exerts a positive modulatory effect on neural repair, with a progressive return of sensory activity. Furthermore, the studies show a wide variation in the number of application points, as well as the irradiation time and number of sessions, due to the extent and time of diagnosis of paresthesia. Final Considerations: Despite the high complexity of paresthesia, the LLL has beneficial effects through the return of partial or total sensitivity in addition being a device well tolerated by the body and minimally invasive.

Photobiomodulation therapy on chemo- and radiotherapy induced oral conditions: an umbrella review.

OBJECTIVES: Photobiomodulation (PBM) is a laser-based therapy used to promote tissue repair, reduce inflammation and pain, and has been extensively studied in chemo- and radiotherapy-induced oral mucositis (OM). This review examines the level of evidence of systematic reviews (SRs) that have investigated PBM in such cases of OM. MATERIALS AND METHODS: SRs evaluating PBM for both the treatment and prevention of OM in patients undergoing chemotherapy and/or radiotherapy and published before November 30, 2023, on PubMed, Cochrane, Embase, Web of Science, LILACS, TRIP and Open Grey databases were eligible for inclusion. We assessed the level of methodological and meta-analytic procedures. RESULTS: Of the 1201 SRs, 21 that met the inclusion criteria were included. The quality of evidence was assessed using the Assessing the Measurement Tool to Assess Systematic Reviews (AMSTAR2), and the majority was of critically low quality (n = 15, 71.4%) with only 28.5% of low quality. A total of 40 meta-analytic estimates were obtained and analyzed. Approximately 87.5% of the meta-analysis were significant (n = 33), but only one meta-analyses had a strength of "highly suggestive", while the rest were classified as "weak". When analyzing the overlap values, the covered area was 12.14% and the corrected covered area was 7.75%, indicating a moderate overlap. Only 4 SRs had a very high overlap and one had a high overlap. CONCLUSION: The efficacy of PBM in the treatment of chemotherapy-induced OM is supported by low to critically low quality SRs and meta-analysis of low strength. This review highlights important areas that need to be addressed in future research on this topic. REGISTRATION: CRD42023484013 (PROSPERO).

Assessment of the onset of analgesia and length of analgesia following the use of PBM with different wavelengths: a clinical study.

This clinical study assessed photobiomodulation (PBM) induced analgesic effects of diode lasers and an LED light source on the dental pulp. Baseline responses to electric pulp testing (EPT) were recorded in 93 healthy unrestored premolar teeth in 26 adults (age range 22-63 years) attending a private dental practice. The teeth were irradiated on buccal and lingual aspects of the crown, by placing the tips on the middle third of the crown of the teeth, on separate days for each of 4 different light sources (660, 808, or 904 nm diode lasers, or a novel multi-wavelength LED light source (700-1100 nm)) using comparable parameters (100 mW, 30 s, 6 J). EPT scores were measured after a further 1-, 2-, 5- and 20-min. Discomfort caused by PBM therapy was recorded using the Wong-Baker scale. EPT changes were tracked over time using repeated measures analysis of variance. Baseline EPT scores were very consistent between different days (linear regression r2 0.9422-0.9648). All PBM devices caused a significant elevation in EPT at 5 min, with an earlier onset at 2 mins for 904 nm and LED. The LED was the only light source that elevated scores at 20 min. Across 2-20 min, when ranked by effectiveness, the greatest EPT elevations were seen for LED, followed by 904 nm, then 660 nm and finally 808 nm. Discomfort during PBM was most common with 904 nm, followed by 808 nm. No discomfort occurred from the LED. Among the light sources utilized, the LED multi-wavelength system demonstrated the largest increase in EPT readings, suggesting its potential as a non-pharmacological alternative for achieving dental analgesia compared to diode lasers.

Effect of photobiomodulation therapy with 660 and 980 nm diode lasers on differentiation of periodontal ligament mesenchymal stem cells.

This study aimed to compare the effects of photobiomodulation therapy (PBMT) with 660 and 980 nm diode lasers on differentiation of periodontal ligament mesenchymal stem cells (PDLMSCs). In this in vitro, experimental study, PDLMSCs were obtained from the Iranian Genetic Bank and cultured in osteogenic medium. They were then subjected to irradiation of 660 and 980 nm diode lasers, and their viability was assessed after one, two, and three irradiation cycles using the methyl thiazolyl tetrazolium (MTT) assay. The cells also underwent DAPI staining, cell apoptosis assay by using the Annexin V/PI, Alizarin Red staining, and real-time polymerase chain reaction (PCR) for assessment of the expression of osteogenic genes. Data were analyzed by two-way ANOVA. The two laser groups had no significant difference in cell apoptosis according to the results of DAPI staining. Both laser groups showed higher cell viability in the MTT assay at 4 and 6 days compared with the control group. Annexin V/PI results showed higher cell viability in both laser groups at 4 days compared with the control group. Rate of early and late apoptosis was lower in both laser groups than the control group at 4 days. Necrosis had a lower frequency in 980 nm laser group than the control group on day 6. Alizarin Red staining showed higher cell differentiation in both laser groups after 3 irradiation cycles than the control group. The highest expression of osteopontin (OPN), osteocalcin (OCN), and Runt-related transcription factor 2 (RUNX2) was noted in 660 nm laser group with 3 irradiation cycles at 14 days, compared with the control group. PBMT with 660 and 980 nm diode lasers decreased apoptosis and significantly increased PDLMSC differentiation after 3 irradiation cycles.

Treatment of Acne Vulgaris-Associated Post-Inflammatory Dyschromia With Combination of Non-Ablative Laser Therapy and Topical Antioxidants.

Acne can cause disfiguring sequelae, such as scarring, post-inflammatory erythema (PIE), and post-inflammatory hyperpigmentation (PIH). These post-inflammatory dyschromias pose a significant psychological burden on patients. This burden disproportionately affects skin of color (SOC) patients and can be the most distressing aspect of acne in SOC patients with skin types IV to VI. Multiple non-ablative lasers are used in the treatment of acne-related PIE and PIH. Combination therapies have shown promise in conditions such as rosacea, acne, and post-inflammatory dyschromia. Addressing both the inflammatory and scarring components of acne is key. Given the role of oxidation in the inflammatory cascade, including antioxidants could be an efficacious adjuvant with non-ablative lasers. This is a single-site, randomized, controlled clinical study of 25 subjects with skin types I to VI with facial PIE and/or PIH from acne. The primary objective was to investigate the clinical efficacy of non-ablative laser therapy followed by the topical application of Silymarin/Salicylic Acid/L-Ascorbic Acid/Ferulic Acid (SSAF) or control in the improvement in oily skin patients with facial PIE and PIH due to acne lesions. There was a statistically significant decrease in PIH and intralesional melanin in patients treated with a combination SSAF and non-ablative laser therapy. Improvement of both PIE and PIH was augmented in combination with SSAF and laser-treated patients compared with the laser-only group, with a concomitant increase in collagen density. This was even more strikingly marked in the SOC subjects, potentially providing an energy-based device (EBD)-based therapy in this population. Limitations of this study include small sample size and length of post-treatment follow-up. J Drugs Dermatol. 2024;23(9):769-773. doi:10.36849/JDD.8309.

Photobiomodulation therapy as an adjunct to resistance exercises on muscle metrics, functional balance, functional capacity, and physical performance among older adults: A systematic scoping review.

This scoping review aims to summarize the literature on photobiomodulation (PBM) therapy as an adjunct to resistance exercise among older adults, focusing on its effects on muscle metrics, functional balance, capacity, and physical performance. The participants included were older adults aged ≥ 60 years and either gender. The concept was the application of PBM and resistance exercises with no limits on the context parameters. The databases Medline, Embase, Scopus and Web of Science were searched from inception till February 2024. Methodological quality was assessed using the Cochrane risk of bias 2.0. A total of 10 studies were included in the review. PBM, along with resistance training, was reported in six studies, whereas four reported PBM with isometric fatigue protocol. PBM with a wavelength of 808 nm was given on the belly of the rectus femoris muscle in most of the studies. The common dosimetry parameters used were- power density 35.7 W/cm2, energy density 250 J/cm2, 8 sites, energy per site 7 J, duration of 70 s per site, spot size per diode of 0.028 cm2, and stationary contact of application. The application of PBM therapy alongside resistance exercise has been found to improve muscle metrics, functional capacity, and functional performance and reduce fatigability when compared with the control group in most of the studies. When incorporating PBM therapy as an adjunct to resistance training, it is crucial to consider the dosimetry parameters involved-to achieve the intended therapeutic effect. Adjusting treatment parameters with this information can optimize the effectiveness of PBM therapy and improve treatment outcomes for patients.

Oral mucositis management with photobiomodulation, Bidens pilosa L. (Asteraceae) and Curcuma longa L. (Zingiberaceae), the FITOPROT herbal medicine, and its influence on inflammatory cytokine levels: a randomized clinical trial.

PURPOSE: This randomized clinical trial aimed to compare the effects of a mucoadhesive formula, containing curcuminoids from Curcuma longa L. and glycerinated extract of Bidens pilosa L. (FITOPROT), associated with photobiomodulation (PBM), and of PBM exclusively, on the incidence of oral mucositis (OM)-induced by radiotherapy (RT) in the head and neck region, and the salivary expression of inflammatory cytokines, in patients with head neck cancer. METHODS: Patients were randomly assigned into two intervention groups-FITOPROT + PBM (n = 25) or PBM (n = 27). PBM protocol comprised a wavelength of 660 nm, 25 mW, 0.25 J/point, and daily irradiation from the first until the last day of RT. FITOPROT was gargled twice a day. All patients underwent a preventive oral care program throughout the study. OM degree, salivary concentration of nitrite, and inflammatory (IL-1, TNFα, IL-6, IL-8, and IL-12p70), and anti-inflammatory (IL-10) cytokines were assessed at baseline, and at the 7th, 14th, 21st, and 30th RT sessions. RESULTS: There were no differences in the OM degree between groups, but the RT dose significantly affected the OM. The RT significantly affected the salivary nitrite, TNFα, IL-1ß, and IL-10 concentrations. CONCLUSION: FITOPROT associated with PBM showed limited effects on preventing the incidence of severe OM compared to PBM alone. However, FITOPROT + PBM may be associated with nitrite and cytokine balance, which may contribute to the occurrence of fewer cases of severe OM. TRIAL REGISTRATION: Brazilian Clinical Trials database (ReBEC; RBR-9vddmr), registered UTN code: U1111-1193-2066, registered in August 8th, 2017.

The impact of photobiomodulation on angiogenic differentiation of two different dental derived stem cells using two irradiation protocols: an in vitro investigation.

The present study aimed to compare the effect of photobiomodulation with different energy densities on the angiogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and stem cells from human exfoliated deciduous teeth (SHED). Photobiomodulation therapy with a 660 nm diode laser (2.4 J/cm2 and 3.9 J/cm2) on two consecutive days post-culture was applied to two types of stem cells (hPDLSCs and SHED). The Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) test was undertaken to investigate Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin I (ANG-I) genes on days 1, 3, 5, 7, and 10 after the first session of laser application. The 4',6-diamidino-2-phenylindole (DAPI) staining and Methyl Thiazolyl Tetrazolium (MTT) test were conducted on days 1, 3, and 5 after the first session of laser application, to assess the cell viability. The Two-way ANOVA with Tukey post hoc test was used to analyze the outcomes of the MTT and RT-qPCR tests. The results of the MTT and DAPI convergently illustrated that the groups receiving photobiomodulation with 2.4 J/cm2 had higher cell viability compared to 3.9 J/cm2. All experimental groups showed an upregulation of VEGF-A and ANG-I gene expression from day 1 to 5, followed by a downregulation from day 5 to 10. The groups with cultured hPDLSCs and SHED receiving photobiomodulation using 2.4 J/cm2 had the most amounts of VEGF-A and ANG-I gene expression on day 5, respectively. In conclusion, the 660 nm mediated photobiomodulation therapy of cultured SHED and hPDLSCs with 2.4 J/cm2 energy density may be associated with higher angiogenic differentiation (the expression of VEGF-A and ANG-I) as well as higher cell viability compared to the photobiomodulation therapy with 3.9 J/cm2.

Features of the regulation of reparative processes of chronic wounds in response to the effect of photobiomodulation therapy on a wound defect. Photobiomodulation therapy for chronic wounds.

BACKGROUND: One of the promising methods of influencing the wound process is photobiomodulation (PBM) therapy. The optimal parameters of PBM therapy have not yet been found because the molecular mechanisms of light interaction with tissue are not fully understood. OBJECTIVE: Studying the influence of PBM of various parameters on the regulation of reparative process- es of chronic wounds using the example of indicators of aggregation activity of platelets, platelet-derived growth factor (PDGF), interleukin-8 (IL-8), and amino-terminal propeptide of type III procollagen (PIIINP) at the remodeling stage. And also the study of the structural and functional features of chronic wound heal- ing in an experiment under various parameters of PBM therapy. METHODS: Experiments were carried out on Wistar rats. Chronic wounds were simulated. Experimental animals were exposed to PBM at a wavelength of 660 nm and an energy density of 1 J/cm2. In serum, PDGF, IL-8, and PIIINP levels were measured by enzyme-linked immunosorbent assay. The functional activity of platelets was measured using the turbidimetric method. Histological analysis was performed. RESULTS: The work noted the dose-dependent effect of PBM using the example of platelet aggregation at the remodeling stage during the healing of chronic wounds. The use of PBM therapy resulted in increased serum PDGF levels. Histological examination data indicate a positive effect of PBM therapy on the wound healing process. CONCLUSIONS: The effectiveness of the use of PBM therapy for the healing of chronic wounds to regulate reparative processes has been proven.

The effect of near-infrared Photobiomodulation therapy on the ion content of 50B11 sensory neurons measured through XRF analysis.

Photobiomodulation therapy (PBMT) is a form of treatment commonly used for routine clinical applications, such as wound healing of the skin and reduction of inflammation. Additionally, PBMT has been explored for its potential in pain relief. In this work, we investigated the effect of PBMT on ion content within the 50B11 sensory neurons cell line in vitro using X-Ray fluorescence (XRF) and atomic force microscope (AFM) analysis. Two irradiation protocols were selected utilizing near-infrared laser lights at 800 and 970 nm, with cell fixation immediately following irradiation. Results showed a decrease in Calcium content after irradiation with both protocols, and with lidocaine, used as an analgesic control. Furthermore, a reduction in Potassium content was observed, particularly evident when normalized to cellular volume. These findings provide valuable insights into the molecular impact of PBMT within 50B11 sensory neurons under normal conditions. Such understanding may contribute to the wider adoption of PBMT as a therapeutic approach.

Near-infrared laser diode mitigates Aß1-42-induced neurodegeneration in cortical neurons.

Alzheimer's disease, a prevalent neurodegenerative condition primarily affecting older adults, remains incurable. Its principle pathological hallmark is the accelerated accumulation of amyloid ß (Aß) protein. This study investigates the potential of photobiomodulation using near infrared light to counteract Aß1-42-induced synaptic degeneration and neurotoxicity. We focused on the effect of 808 nm near-infrared laser diode (LD) on Aß1-42 cytotoxicity in primary cultured cortical neurons. We assessed cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, observing substantial benefits from LD irradiation with a power of 10 mW and a dose of 30 J. Cells exposed to Aß1-42 exhibited morphological changes indicative of synaptic damage and a significant decrease in the number of postsynaptic density protein-95 (PSD-95) contacts, which were significantly improved with near-infrared LD therapy. Furthermore, this therapy reduced Aß and phosphorylated tau (P-tau) protein accumulation. Additionally, near-infrared LD irradiation substantially lessened the Aß1-42-induced rise in glial fibrillary acid protein (GFAP) and ionized calcium-binding adaptor molecule 1 (IBA1) in astrocytes and microglia. Remarkably, near-infrared LD irradiation effectively inhibited phosphorylation of key proteins involved in Aß1-42-induced necroptosis, namely Receptor-interacting protein kinase-3 (RIP3) and Mixed Lineage Kinase domain-Like protein (MLKL). Our findings suggest that near-infrared LD treatment significantly reduces neurodegeneration by reducing glial overactivation and neuronal necroptosis triggered by Aß1-42. Thus, near-infrared LD treatment emerges as a promising approach for slowing or treating Alzheimer's disease, offering new avenues in its management.

Photobiomodulation Dose-Response on Adipose-Derived Stem Cell Osteogenesis in 3D Cultures.

Osteoporosis and other degenerative bone diseases pose significant challenges to global healthcare systems due to their prevalence and impact on quality of life. Current treatments often alleviate symptoms without fully restoring damaged bone tissue, highlighting the need for innovative approaches like stem cell therapy. Adipose-derived mesenchymal stem cells (ADMSCs) are particularly promising due to their accessibility, abundant supply, and strong differentiation potential. However, ADMSCs tend to favor adipogenic pathways, necessitating the use of differentiation inducers (DIs), three-dimensional (3D) hydrogel environments, and photobiomodulation (PBM) to achieve targeted osteogenic differentiation. This study investigated the combined effects of osteogenic DIs, a fast-dextran hydrogel matrix, and PBM at specific wavelengths and fluences on the proliferation and differentiation of immortalized ADMSCs into osteoblasts. Near-infrared (NIR) and green (G) light, as well as their combination, were used with fluences of 3 J/cm2, 5 J/cm2, and 7 J/cm2. The results showed statistically significant increases in alkaline phosphatase levels, a marker of osteogenic differentiation, with G light at 7 J/cm2 demonstrating the most substantial impact on ADMSC differentiation. Calcium deposits, visualized by Alizarin red S staining, appeared as early as 24 h post-treatment in PBM groups, suggesting accelerated osteogenic differentiation. ATP luminescence assays indicated increased proliferation in all experimental groups, particularly with NIR and NIR-G light at 3 J/cm2 and 5 J/cm2. MTT viability and LDH membrane permeability assays confirmed enhanced cell viability and stable cell health, respectively. In conclusion, PBM significantly influences the differentiation and proliferation of hydrogel-embedded immortalized ADMSCs into osteoblast-like cells, with G light at 7 J/cm2 being particularly effective. These findings support the combined use of 3D hydrogel matrices and PBM as a promising approach in regenerative medicine, potentially leading to innovative treatments for degenerative bone diseases.

Aplicação clínica da laserterapia de baixa potência na atenção primária à saúde / Clinical praxis of low-level laser therapy in primary health care

LASER é um acrônimo que sumariza a amplificação da luz por emissão estimulada de radiação (eletromagnética). O Programa Saúde em Ação equipou diversas Unidades Básicas de Saúde com aparelhos de laser diodo. Cirurgiões Dentistas têm aplicado a laserterapia de baixa potência para acelerar a remissão de várias condições clínicas, sem necessidade de encaminhamento imediato para Atenção Secundária. O objetivo deste artigo é apresentar protocolos de laserterapia de baixa potência empregados por Cirurgiões Dentistas da Atenção Primária à Saúde de Campinas-SP, por meio da ilustração com casos clínicos atendidos em consultas de urgência. Aplicações para ulceração traumática e desordem temporomandibular foram realizadas em uma senhora de 60 anos de idade, que aguardava a substituição das próteses totais. Irradiou-se por laser vermelho (660nm) com energia de 1J as margens da ulceração. Após palpação da articulação e dos músculos mastigatórios para mapeamento, os pontos álgicos foram irradiados por laser infravermelho (808nm) com energia de 4J. Um homem de 50 anos de idade queixava-se de paralisia hemifacial havia 10 dias. A tentativa de recuperação do nervo facial ocorreu com irradiação por laser infravermelho com energia de 8J por ponto, em 22 pontos dos ramos do nervo facial. Em ambos os casos, a regressão do quadro clínico desconfortável foi observada. Os Profissionais do Sistema Único de Saúde (SUS) que são aptos ao uso dos equipamentos para laserterapia de baixa potência podem utilizar este recurso de modo seguro e bem sucedido, observando comprimento de onda do laser e doses protocolares para cada alteração a ser tratada.

LASER is an acronym which means light amplification by stimulated emission of radiation (electromagnetic). Many Primary Health Care Units received diode laser devices from the Brazilian Health in Action Program. Dental practitioners have applied low-level laser therapy for accelerating the resolution of several clinical problems, without the need to prompt referral for Secondary Attention. This manuscript aimed at presenting low-level laser therapy protocols, used by Dentists in Primary Health Care Units from Campinas-SP, illustrated with case reports of urgency consultations. Applications for traumatic ulcers and temporomandibular disorder were performed in a 60-year-old woman who was waiting for dental prosthesis replacement. Red laser irradiation (660nm) with 1J energy was delivered at the margins of the ulcer. Upon articular and masticatory muscles palpation for mapping, trigger points were irradiated with infrared laser (808nm), 4J energy. A 50-year-old man complained of hemifacial paresis for 10 days. The recovery attempt of the facial nerve was carried out by infrared laser irradiation with 8J energy per point in 22 points of the facial nerve branches. In both case reports, regression of the uncomfortable clinical problem was noted. Professionals from the Unified Health System (SUS) who are able to use a low-level laser device may safe and successfully operate this equipment, selecting the appropriate laser wavelength and protocol doses for managing each clinical problem.

In-vitro study on type I collagen synthesis in low-level laser therapy on the early ligament fibroblasts' healing process.

BACKGROUND: Low-level Laser Therapy (LLLT) has demonstrated its potential in promoting fiber matrix maturation, collagen synthesis, and fibroblast proliferation, contributing to tissue regeneration. Our study aimed to investigate the impact of LLLT on collagen type I synthesis, cell proliferation, and viability in human ligament fibroblasts derived from the Anterior Cruciate Ligament (ACL). METHODS: Tissue samples were obtained from individuals undergoing arthroscopic ACL reconstruction surgery. Primary human fibroblasts were isolated, and immunohistochemical assays confirmed their characteristics. LLLT at 850 nm was administered in three groups: Low dose (1.0 J/cm²), High dose (5.0 J/cm²), and Control (0.0 J/cm²). Cell viability was calculated using a membrane integrity assay, proliferation was determined by automated counting, and collagen type I concentration in cell culture was measured using an immunoassay. RESULTS: Fibroblasts showed decreased viability after low and high doses of LLLT, increased proliferation at the low dose, and increased collagen synthesis at the high dose on day 10 for both sexes after treatment. CONCLUSION: Our study demonstrated that LLLT may improve the early ligament healing process by increasing cell proliferation at the low dose and enhancing collagen type I synthesis at the high dose in human ligament fibroblasts.

Comprehensive analysis of bone tissue in extraction sockets of third molars after leukocyte and platelet rich fibrin and photobiomodulation applications.

OBJECTIVES: The aim of this study was to compare leukocyte and platelet-rich fibrin (L-PRF) and photobiomodulation (PBM) applications, which have been repeatedly reported to be superior to control groups, in terms of pain, soft tissue and bone healing in tooth extraction sockets. MATERIALS AND METHODS: This double-blind, randomized clinical study was completed with 34 patients, who had an indication for extraction of their bilaterally impacted teeth. The right and left teeth of the patients were randomly divided into L-PRF and PBM groups. L-PRF group was treated with the blood product centrifuged for 12 min at 2700 rpm, and the PBM group was treated with a diode laser at different points for 60 s with a wavelength of 940 nm in repeated sessions. Postoperative pain was evaluated using Visual Analogue Scale (VAS), soft tissue healing with Landry Index (LI), tissue healing in the distal region of mandibular second molar by probing depth measurement, and bone healing via panoramic x-ray using the Image J program. RESULTS: No statistically significant difference was found for any variable compared between the groups. CONCLUSION: L-PRF and PBM applications provide similar support in the healing of extraction sockets. Nevertheless, the advantages and disadvantages of both methods determine their usage areas. CLINICAL RELEVANCE: While L-PRF is advantageous in the early healing of extraction sockets, PBM may be preferred in terms of bone trabeculation in the long term.

Transcranial photobiomodulation on the left inferior frontal gyrus enhances Mandarin Chinese L1 and L2 complex sentence processing performances.

This study investigated the causal enhancing effect of transcranial photobiomodulation (tPBM) over the left inferior frontal gyrus (LIFG) on syntactically complex Mandarin Chinese first language (L1) and second language (L2) sentence processing performances. Two (L1 and L2) groups of participants (thirty per group) were recruited to receive the double-blind, sham-controlled tPBM intervention via LIFG, followed by the sentence processing, the verbal working memory (WM), and the visual WM tasks. Results revealed a consistent pattern for both groups: (a) tPBM enhanced sentence processing performance but not verbal WM for linear processing of unstructured sequences and visual WM performances; (b) Participants with lower sentence processing performances under sham tPBM benefited more from active tPBM. Taken together, the current study substantiated that tPBM enhanced L1 and L2 sentence processing, and would serve as a promising and cost-effective noninvasive brain stimulation (NIBS) tool for future applications on upregulating the human language faculty.

Laryngeal photobiomodulation: application sites, interferences from body mass index and skin phototype.

PURPOSE: Establish points on the neck, correspondent to the laryngeal topography, where to apply Low Level Light therapy (LLLT), to evaluate the incidence of light through variables such as skin phototype and body mass index (BMI). METHODS: This is a cross-sectional, analytical, observational study, carried out with 15 vocally healthy women, between 18 and 50 years of age, who were divided into three groups, according to BMI and skin phototype. Six anatomical reference points were established to locate the larynx and its musculature, with visual monitoring by videonasolaryngoscopy, to assess light reach (present/absent) and degree of illumination (from very weak to very strong) in the larynx during the LASER application at doses of 3J, 6J and 9J. A flexible endoscope was used for visual monitoring during the LASER application, and subsequent image analysis. RESULTS: The light reached the larynx at doses of 3J, 6J and 9J, in the anterior commissure of the vocal folds, membranous (thyroarytenoid muscle) and cartilaginous portions of the vocal fold and the cricothyroid muscle. The degree of LASER light illumination decreased in overweight and obese participants and increased in moderate brown and dark brown skin phototypes. CONCLUSION: Data suggest that the LLLT penetrates differently according to skin phototype and BMI, being more evident in individuals with Fitzpatrick IV and V phototypes and less evident with higher BMI levels. The evidence that the LASER light reaches the larynx in specific anatomical points provides direction for the standardization of its use in voice practice.

Transcranial Photobiomodulation Therapy as an Intervention for Opioid Cravings and Depression: A Pilot Cohort Study.

Introduction: The opioid crisis, a declared national health emergency, has prompted the exploration of innovative treatments to address the pervasive issues of opioid cravings and associated depression. Aims: This pilot cohort study investigated the efficacy of transcranial Photobiomodulation (tPBM) therapy using the SunPowerLED helmet to alleviate these symptoms in individuals undergoing treatment for opioid addiction at a rehabilitation center in West Virginia. Methods: Employing a quasi-experimental design, this study enrolled participants into two groups: one receiving tPBM therapy alongside standard care and a control group receiving standard care alone. The helmet features include the following: total wavelength = 810 nm, total irradiance = 0.06 W/cm2 (60 m W/cm2), and total fluence = 172.8J/cm2. Results: The results of the Wilcoxon signed-rank tests for within-group analysis and Mann-Whitney U tests for between-group comparisons revealed statistically significant reductions in the intensity (W = 7.36, p = 0.012), time (W = 6.50, p = 0.015), frequency (W = 6.50, p = 0.010), and total scores of opioid cravings (W = 7.50, p = 0.009), as well as improvements in depression symptoms (W= 8.00, p = 0.005) within the PBM group compared to the non-PBM group. Discussion: These findings suggest that transcranial PBM therapy could be a promising noninvasive intervention for reducing opioid cravings and depressive symptoms in individuals with opioid use disorder, warranting further investigation through larger randomized controlled trials.

Lens Fragmentation with Picosecond Laser Pulses After Artificial Cataract Induction with Microwaves.

Objectives: In this work we demonstrate the first laboratory study results of lens fragmentation with low-energy picosecond ultrashort laser pulses after artificial induction of cataract with microwave radiation on an ex vivo animal model. Background: This method will be evaluated with regard to the further development of lens fragmentation with novel ultrashort picosecond laser systems instead of ultrasonic phacoemulsification or the significantly more complex femtosecond laser fragmentation. Methods: As samples we used postmortem porcine eyes. The lenses were dissected and then irradiated in a microwave oven for artificial cataract induction. Subsequent computer-driven lens fragmentation was performed with a 12 ps, 1064 nm pulsed laser source with 100 µJ pulse energy, and 10 kHz pulse repetition rate. Results: Both the artificial cataract induction and the lens fragmentation were demonstrated. When inducing cataract, different degrees/stages of opaqueness and hardness could be achieved with different irradiation times and methods. The fragmentation with 12 ps pulses led to good results with regard to ablation depth and rate, especially for the softer lenses. Conclusions: As could be shown, low-energy picosecond ultrashort laser pulses are feasible for cataractous lens fragmentation on an ex vivo animal model with artificial cataract induction. Thus, this technique may influence future cataract surgeries by possibly being an alternative or extension to state-of-the-art methods. This will be evaluated with further tests and studies.

The Mechanism of 540 nm Green Light in Promoting Salivary Secretion.

Background: Although low-level laser therapy (LLLT) is a widely used noninvasive treatment because of photobiomodulation effects, its application for xerostomia remained uncertain. Tight junctions (TJs), mainly composed of claudins, occludin, and ZO family members, are crucial structures that determine material transport through paracellular pathway in salivary gland epithelial cells. This work aimed to investigate whether LLLT affected salivary secretion through epithelial TJs. Methods: Transepithelial electrical resistance (TER) measurement and paracellular permeability assay were applied to evaluate paracellular permeability in submandibular gland (SMG)-C6 cells after irradiation with 540 nm green light. Immunofluorescence and western blot were used to detect the expression of TJ proteins. Quantitative phosphoproteomics were performed to explore possible intracellular signals. Results: We found that irradiation with 540 nm green light significantly decreased TER values while increased paracellular transport in SMG-C6 cells. 540 nm green light-induced redistribution of claudin-1, -3, and -4, but not occludin or ZO-1. Moreover, above phenomena were abolished by preincubation with capsazepine, an antagonist of transient receptor potential vanilloid subtype 1. Notably, irradiation with 540 nm green light on the skin covering the whole submandibular gland regions promoted salivary secretion and attenuated lymphocytic infiltration in 21-week-old non-obese diabetic mice (n = 5 per group), a xerostomia animal model for Sjögren's syndrome. Through in-depth bioinformatics analysis and expression verification, ERK1/2 and EphA2 served as potential canonical and noncanonical signals underlying 540 nm green light. Conclusions: Our findings uncovered the novel therapeutic effects of 540 nm green light on xerostomia through regulation on the expression and distribution of TJs.