Effects of low-power laser irradiation (LPLI) at different wavelengths and doses on oxidative stress and fibrogenesis parameters in an animal model of wound healing

The effect of light-emitting diode-mediated photobiomodulation therapy on orthodontic tooth movement: A literature review

This study aims to review and analyze the impact of light-emitting diode (LED) photobiomodulation (PBM) therapy on orthodontic tooth movement. This non-invasive technique is proposed to reduce time-related side effects, such as white spot lesions, dental caries, and root resorption. Five studies were included in the review, comprising two animal studies (ages 10 and 12 weeks) and three human studies (ages ranging from 15 to 17 years). All studies applied PBM concurrently with force application using sliding mechanics for canine retraction (three studies) and molar protraction (two studies). Two studies employed LEDs with a wavelength of 850 nm, with an exposure time of 5 min daily. Another two studies used LEDs with a wavelength of 618 nm, with an exposure time of 20 min daily. In summary, these studies demonstrated that LED-mediated PBM enhanced orthodontic tooth movement by 33 % (a 1.36-fold increase) compared to the control group. The mean tooth movement per month was 1.55 ± 0.33 mm, which was higher than the control group's average of 1.06 ± 0.35 mm. Also, no studies demonstrated any side effects such as anchorage loss, root resorption, canine rotation, or tooth inclinations. In conclusion, LED-mediated PBM (at wavelengths of 618 nm and 850 nm) can accelerate orthodontic tooth movement without adverse effects, thanks to its biostimulatory properties. Given the advantages of LEDs over traditional lasers-particularly their lower cost and easier application-this method shows promise as a tool to accelerate tooth movement, potentially reducing treatment time and associated side effects.

Diabetic rats skin wounds treated with heterologous fibrin sealant followed by photobiomodulation therapy

Diabetes mellitus is characterized by elevated blood glucose levels causing sometimes impairment of the body's ability to repair itself. Promising treatments for tissue repair have included photobiomodulation therapy and heterologous fibrin biopolymer (HFB). This study aimed to evaluate the impact of photobiomodulation therapy by LED, both as a standalone treatment and in conjunction with heterologous fibrin biopolymer in treatment of skin lesions of diabetic rats. Diabetes was induced using alloxan. Full-thickness skin wounds were induced on the backs of 56 Wistar rats, which were randomly allocated into four groups: control group, heterologous fibrin biopolymer group, photobiomodulation therapy by LED group, and photobiomodulation therapy by LED combined with heterologous fibrin biopolymer group. The treatments spanned two experimental periods, lasting 7 and 14 days. Notably, the HFB group exhibited results similar to those of the LED group concerning wound regression, while demonstrating superior resistance to healing. Interestingly, the LED + HFB group showed greater skin damage at 7 days, but an improved repair process at 14 days compared to the control group. The findings indicate that combining photobiomodulation by LED with HFB did not enhance wound healing in diabetic rats beyond the effects of each treatment alone. Both treatments were effective individually, with HFB showing particular strength in promoting collagen maturation and improving tissue biomechanical properties. This study contributes to the ongoing body of research on skin repair with this innovative HFB. Future clinical trials will be essential to validate this proposition.

The impact of antimicrobial photodynamic therapy on pain and oral health-related quality of life: A literature review

Antimicrobial photodynamic therapy (aPDT) is a non-invasive approach used for microbial decontamination, and it can also be beneficial as an adjunctive strategy for oral infections. The success of treatment in the long term is increasingly recognized to be influenced by patient's perception of the disease and its improvement. Recently, aPDT has been suggested as a dual approach to tissue repair, pain relief, and enhancement of oral health-related quality of life (OHRQoL). The first pathway involves the antimicrobial and anti-inflammatory effects of aPDT. It not only eliminates microorganisms but also helps regulate the immune response and reduce inflammation, leading to a faster and more effective healing process. This, in turn, provides relief from pain and associated symptoms, aiding in the management of treatment complications. The second pathway involves aPDT's ability to modulate nociception and alleviate pain. aPDT induces analgesia by releasing neurotransmitters such as β-endorphin, serotonin, and acetylcholinesterase. It also interacts with mitochondria through photoreceptors, initiating intracellular processes that alleviate pain. Furthermore, the therapy inhibits nerve fibers, reducing nerve impulse conduction and altering the pain threshold. Considering that the impact on patients' pain and OHRQoL is an important aspect of the decision-making process, this study aimed to review patient-based outcome measures during aPDT and assess its effects on pain and OHRQoL in patients. Understanding these factors will contribute to a better assessment of the overall benefits and effectiveness of aPDT as a treatment option for oral infections.

Indole-3-carbinol loaded-nanocapsules modulated inflammatory and oxidative damages and increase skin wound healing in rats

This study evaluated the effects of topically applied hydrogels (HG) containing nanoencapsulated indol-3-carbinol (I3C) and its free form in a rat model of skin wounds. Formulations were topically applied twice a day for five days to the wounds. On days 1, 3, and 6, the wound area was measured to verify the % of regression. On the sixth day, the animals were euthanized for the analysis of the inflammatory and oxidative profile in wounds. The nanocapsules (NC) exhibited physicochemical characteristics compatible with this kind of suspension. After five hours of exposure to ultraviolet C, more than 78% of I3C content in the suspensions was still observed. The NC-I3C did not modify the physicochemical characteristics of HG when compared to the HG base. In the in vivo study, an increase in the size of the wound was observed on the 3rd experimental day, which was lower in the treated groups (mainly in HG-NC-I3C) compared to the control. On the 6th day, HG-I3C, HG-NC-B, and HG-NC-I3C showed lower regression of the wound compared to the control. Additionally, HG-NC-I3C exhibited an anti-inflammatory effect (as observed by decreased levels of interleukin-1B and myeloperoxidase), reduced oxidative damage (by decreased reactive species, lipid peroxidation, and protein carbonylation levels), and increased antioxidant defense (by improved catalase activity and vitamin C levels) compared to the control. The current study showed more satisfactory results in the HG-NC-I3C group than in the free form of I3C in decreasing acute inflammation and oxidative damage in wounds.

Effect of Laser Therapy on Postoperative Pain and Endodontic Retreatment: A Systematic Review and Meta-Analysis

BACKGROUND

Root canal re-treatment (RCR) cases are considered some of the most challenging cases in the field of endodontics, as they are mostly associated with various iatrogenic errors such as ledge formation, incomplete biomechanical preparation, file separation, and incomplete obturation. These iatrogenic errors lead to defective niches within root canals that may act as reservoirs for various viable microorganisms. Such residual microbial niches may cause postoperative pain even after thorough debridement and reshaping the canals, ultimately leading to a poor prognosis for the tooth. Nowadays, prevention of postoperative pain in re-treatment cases and prognosis are effectively managed by photobiomodulation therapy (PBMT).

METHOD

Relevant studies in the English language published before November 2022 were identified using electronic databases like PubMed, SCOPUS, and EBSCO to conduct bibliographic research. This systematic review is based on 3 studies that were found eligible as per the inclusion and exclusion criteria. This systematic review is in accordance with PRISMA guidelines.

RESULTS

The systematic review indicated a positive impact by significantly decreasing postoperative pain in RCR cases when treated with PBMT. The variation was statistically significant at 24 hours (P = .0002), 48 hours (P = .03), and 72 hours (P = .02). The mean difference at 24 hours was 0.65 (95% CI, 0.32-0.99), at 48 hours was 0.46 (95% CI, 0.05-0.87), and at 72 hours was 0.40 (95% CI, 0.07-0.74). There was no statistical heterogenicity at 24 hours (P > .05), but a medium heterogenicity was observed at 48 hours and 72 hours.

PRACTICAL IMPLICATION

PBMT or low-level laser therapy has shown superior results as compared to the conventional pharmacologic approach in postoperative pain management in RCR cases.

Radioreparative Effect of Diode Laser on Leukopoiesis Recovery: A Pilot Study

The aim of the present study was to investigate the effect of laser therapy on leukopoiesis recovery after irradiation with ionizing radiation. A dose of ionizing radiation was used that induced the hematological form of radiation sickness, reducing the number of blood cells. Subsequently, mice were treated with non-ionizing laser radiation. Based on the examination of the peripheral blood, the study found that laser therapy significantly impacted the number of eosinophils and basophils two weeks after irradiation. Laser therapy also led to the faster reparation of the lymphocyte lineage of white blood cells (WBCs). The research showed that the examined therapeutic laser had a long-term radioreparative effect on gamma-irradiated mice, improving the absolute counts of different lines of WBCs. The results of this study could have implications for the treatment of radiation sickness in humans.

The Effects and Mechanisms of PBM Therapy in Accelerating Orthodontic Tooth Movement

Malocclusion is one of the three major diseases, the incidence of which could reach 56% of the imperiled oral and systemic health in the world today. Orthodontics is still the primary method to solve the problem. However, it is clear that many orthodontic complications are associated with courses of long-term therapy. Photobiomodulation (PBM) therapy could be used as a popular way to shorten the course of orthodontic treatment by nearly 26% to 40%. In this review, the efficacy in cells and animals, mechanisms, relevant cytokines and signaling, clinical trials and applications, and the future developments of PBM therapy in orthodontics were evaluated to demonstrate its validity. Simultaneously, based on orthodontic mechanisms and present findings, the mechanisms of acceleration of orthodontic tooth movement (OTM) caused by PBM therapy were explored in relation to four aspects, including blood vessels, inflammatory response, collagen and fibers, and mineralized tissues. Also, the cooperative effects and clinical translation of PBM therapy in orthodontics have been explored in a growing numbers of studies. Up to now, PBM therapy has been gaining popularity for its non-invasive nature, easy operation, and painless procedures. However, the validity and exact mechanism of PBM therapy as an adjuvant treatment in orthodontics have not been fully elucidated. Therefore, this review summarizes the efficacy of PBM therapy on the acceleration of OTM comprehensively from various aspects and was designed to provide an evidence-based platform for the research and development of light-related orthodontic tooth movement acceleration devices.

Low-power laser in increasing doses improve wound healing process in rats

Low-power laser has been studied and applied as an auxiliary tool in wound healing. However, as it is a therapy with several variables to be controlled, there is great difficulty in establishing protocols and comparing its efficacy. Therefore, the objective of this study was to evaluate the effects of the use of low-power laser in fixed and crescent doses in the healing of skin wounds in rats. Seventy-five male Wistar rats were divided into three groups: G1 with animals that did not receive laser radiation; G2 with animals treated with fixed dose of 3 J/cm2 laser; G3 with animals treated with laser in increasing doses of 1 J/cm2, 3 J/cm2, 5 J/cm2. Macroscopic and histological analysis were performed. The lowest intensity of PMN was observed in the irradiated groups and G3 had lower intensity of this infiltrate compared to G1 and G2 (p <0.05). On the seventh day of injury, PMN infiltrate decreased in all groups, especially in G3 (p<0.05). It was observed that G2 had more blood vessels than G1 and G3 after 7 days of wound creation (p ˂ 0.05). Collagen quantification showed that laser-treated groups have increased collagen deposition. Different responses in the wound healing process were observed comparing G2 and G3 groups. The fluence of 1J/cm2 presented better results in the anti-inflammatory action than 3 J/cm2, although G3 presented the greatest amount of total collagen after ten days of treatment.

The Combined Effects of a Methacrylate Powder Dressing (Altrazeal Powder) and Photobiomodulation Therapy on the Healing of a Severe Diabetic Foot Ulcer in a Diabetic Patient: A Case Report

Weakened wound healing is a popular, severe complication of patients with diabetes which poses a risk for foot infection and amputation. Researchers have searched for new treatments for treating diabetic foot ulcers (DFUs) in recent years. In this case report, for the first time, we applied photobiomodulation therapy (PBMT) and Altrazeal powder together to treat a severe case of DFU in a 47-year-old woman who was suffering from type 1 diabetes. Along with the progress of combination therapy, we observed that the ulcer area was significantly reduced, and the wound healed within 16 weeks. Furthermore, dermatitis and purulent secretion were treated, and the pain was reduced. This reported case study indicated the beneficial effect of the combination of PBMT and Altrazeal powder for the healing of a severe DFU in a patient with type one diabetes. The combined application of PBMT plus Altrazeal powder demonstrated an additive effect. Further clinical trials in the clinical setting are suggested to validate the results further. Besides, more studies in preclinical models are suggested to find the mechanism of the action of combination therapy.

Can Photobiomodulation Therapy (PBMT) Minimize Exercise-Induced Oxidative Stress? A Systematic Review and Meta-Analysis

Oxidative stress induced by exercise has been a research field in constant growth, due to its relationship with the processes of fatigue, decreased production of muscle strength, and its ability to cause damage to the cell. In this context, photobiomodulation therapy (PBMT) has emerged as a resource capable of improving performance, while reducing muscle fatigue and muscle damage. To analyze the effects of PBMT about exercise-induced oxidative stress and compare with placebo therapy. Data Sources: Databases such as PubMed, EMBASE, CINAHL, CENTRAL, PeDro, and Virtual Health Library, which include Lilacs, Medline, and SciELO, were searched to find published studies. Study Selection: There was no year or language restriction; randomized clinical trials with healthy subjects that compared the application (before or after exercise) of PBMT to placebo therapy were included. Study Design: Systematic review with meta-analysis. Level of Evidence: 1. Data Extraction: Data on the characteristics of the volunteers, study design, intervention parameters, exercise protocol and oxidative stress biomarkers were extracted. The risk of bias and the certainty of the evidence were assessed using the PEDro scale and the GRADE system, respectively. Results: Eight studies (n = 140 participants) were eligible for this review, with moderate to excellent methodological quality. In particular, PBMT was able to reduce damage to lipids post exercise (SMD = −0.72, CI 95% −1.42 to −0.02, I2 = 77%, p = 0.04) and proteins (SMD = −0.41, CI 95% −0.65 to −0.16, I2 = 0%, p = 0.001) until 72 h and 96 h, respectively. In addition, it increased the activity of SOD enzymes (SMD = 0.54, CI 95% 0.07 to 1.02, I2 = 42%, p = 0.02) post exercise, 48 and 96 h after irradiation. However, PBMT did not increase CAT activity (MD = 0.18 CI 95% −0.56 to 0.91, I2 = 79%, p = 0.64) post exercise. We did not find any difference in TAC or GPx biomarkers. Conclusion: Low to moderate certainty evidence shows that PBMT is a resource that can reduce oxidative damage and increase enzymatic antioxidant activity post exercise. We found evidence to support that one session of PBMT can modulate the redox metabolism.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm²) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

An Evaluation of the Effects of Photobiomodulation Therapy on the Peri-Implant Bone Healing of Implants with Different Surfaces: An In Vivo Study

(1) Background: This study evaluates the effects of photobiomodulation (PBM) therapy on the peri-implant bone healing of implants with a machined surface (MS) and treated surface (TS). (2) Methods: Topographic characterization of the surfaces (scanning electron microscopy [SEM]- energy dispersive X-ray spectroscopy [EDX]) was performed before and after implant removal. Twenty rabbits were randomly divided into four groups: MS and TS groups (without PBM therapy) and LMS and LTS groups (with PBM therapy). After implant placement, the stability coefficient (ISQ) was measured. In the periods of 21 and 42 days, the ISQ was measured again, followed by biomechanical analysis. (3) Results: The surfaces of the TS implants showed topographic differences compared with MS implants. The ISQ values of the LMS were statistically significant when compared with those of the MS at 42 days (p < 0.001). The removal torque values of the LMS were statistically significant when compared with those of the MS at 21 days (p = 0.023) and 42 days (p = 0.023). For SEM, in general, the LMS, TS and LTS presented high bone tissue coverage when compared to MS. (4) Conclusions: The PBM therapy modulated the osseointegration process and was evidenced mainly on the machined surface.

Photobiomodulation associated with lipid nanoparticles and hyaluronic acid accelerate the healing of excisional wounds

Objectives: This article aimed to investigate the effects of the association between photobiomodulation and hyaluronic acid incorporated in lipid nanoparticles in an epithelial lesion model in inflammatory parameters and oxidative stress. Methods: Eighty Wistar rats were randomly assigned to the following groups: epithelial lesion group (EL); EL+PBM; EL+HA; EL+SLNs; EL+SLNs-HA; EL+PBM+HA; EL+PBM+SLNs; EL+PBM+SLNs-HA. The animals were anesthetized with 4% isofluorane after shaving and induced to an epithelial lesion. Topical treatment with a gel containing HA (0.9%) and/or SLNs (10 mg/mL) and with laser irradiation occurred daily for 1 week. Results: The results showed an increase in wound contraction on the seventh day in the LE + LBM + AH-NPL group, a reduction in pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α), an increase in anti-inflammatory cytokines (IL- 4 and IL-10) and TGF-β. The levels of pro-inflammatory cytokine IL-4 and TGF-β also showed an increase in the LE + NPL-AH, LE + FBM + AH, LE + FBM + NPL and LE + FBM + NPL-AH groups. Regarding oxidative stress parameters, the levels of DCF and nitrite decreased in the combined therapy group when compared to the control group, as well as oxidative damage (carbonyl and sulfhydryl). In the antioxidant defense, there was an increase in GSH and SOD in the combination therapy group. Histological analysis showed a reduction in inflammatory infiltrate in the combination therapy group. The number of fibroblasts and the compaction of collagen fibers did not obtain significant responses. Conclusions: Results analyzed together showed that the combined therapy favored the repair process, and that studies can be carried out to enhance the histological analysis therapy favored the tissue repair process and that studies can be carried out to enhance the histological analysis.

Photobiomodulation and photodynamic therapy applied after electrocauterization for skin healing optimization in rats

Photobiomodulation-PBM and Photodynamic Therapy-PDT have been used to induce healing. However, the effects of these therapies on skin-lesions induced by electrocautery are unknown, aiming at more favorable clinical and esthetic results. Electrocauterization was done in 78-female Wistar-rats using a system that includes an electrocautery and red-LED. The groups were: No injury, Injury, Injury + ALA (topical 5-aminolevulinic acid application), Injury + LED and Injury + ALA + LED (topical ALA application followed by photoactivation with LED). After 2nd, 7th and 14th days post-injury, immuno-histomorphometric analyses (inflammatory infiltrate, blood vessels, fibroblasts, eschar/epidermal thickness, IL-10 and VEGF) and biochemical assays of MPO (neutrophil), NAG (macrophage), nitrite, DCF (H₂ O₂ ), carbonyl (membrane's damage), sulfhydryl (membrane's integrity), SOD, GSH, hydroxyproline and re-epithelialization area were performed. The Injury + LED and Injury + ALA + LED groups controlled inflammation and oxidative stress, favoring angiogenesis, fibroblasts proliferation and collagen formation. Therefore, the PBM or PDT was effective in tissue formation with thinner eschar and epidermis, resulting in less scarring after electrocauterization.

Optimization of photo-biomodulation therapy for wound healing of diabetic foot ulcers in vitro and in vivo

Unclear optical parameters make photo-biomodulation (PBM) difficult to implement in diabetic foot ulcer (DFU) clinically. Here, 12 wavelengths (400-900 nm) were used to conduct PBM to heal DFU wounds in vitro and in vivo. PBM at 10 mW/cm² and 0.5-4 J/cm² with all 12 wavelengths promoted proliferation of diabetic wound cells. In a mimic DFU (mDFU) rat model, PBM (425, 630, 730, and 850 nm, and a combination light strategy) promoted mDFU healing. The positive cell proliferation, re-epithelialization, angiogenesis, collagen synthesis, and inflammation were possible mechanisms. The combination strategy had the best effect, which can be applied clinically.

The Effects of Periodontal Laser Therapy on Pain in Adult Patients with Orthodontic Treatment: A Randomized Clinical Trial

(1) Background: Pain is the most common complaint of patients with fixed orthodontic treatment, especially when applying and activating the orthodontic device. The effectiveness of low-level laser therapy (LLLT) in reducing pain caused by the orthodontic treatment has been frequently studied over the last few years. In this study, we aim to evaluate the influence of laser therapy on pain caused by orthodontic forces acting on periodontal tissues during fixed orthodontic treatment. (2) Methods: A total of 36 patients who met the inclusion criteria were submitted to laser therapy after beginning a fixed orthodontic treatment. For each patient, one half-arch was treated with laser (HL), the opposite one being the control half-arch (HC). The evaluation of pain was conducted by asking the patients to rate their pain on a VAS scale from 0 to 10. (3) Results: Analyzing the VAS score values reported after applying the orthodontic device, we noticed that the pain increased in the first few hours, it was the highest 24 h after application, and it decreased towards the 7th day. The pain reported by most patients was significantly reduced in the HL compared to the HC, in all three moments that were evaluated (p < 0.0001). (4) Conclusions: Repeated LLLT in patients with orthodontic treatment leads to a significant decrease in pain levels, as the comparison between the laser half-arch and the control half-arch showed.

Effectiveness of sodium fluoride varnish and/or diode laser in decreasing post-bleaching hypersensitivity: A comparative study

Background

Professional tooth whitening has gained popularity in the past several years. The most commonly active chemical agent used in bleaching is hydrogen peroxide (HP). HP is a low molecular weight unstable material that easily diffuses into the tooth structure, causing oxidative reactions with a consequent whitening effect. After bleaching, tooth sensitivity and gingival irritation are anticipated.

Aim

This study aimed to compare the effectiveness of remineralization and/or diode laser therapies in reducing tooth sensitivity after bleaching.

Methodology

Thirty-nine participants from Umm Al-Qura University, dental clinics, Makkah, SA. They were divided into three equal groups according to the desensitizing technique used. All participants were subjected to bleaching by 40% opalescence boost HP. Subsequently, 13 participants received 5% sodium fluoride varnish (5% NaF), 13 participants received low-level laser therapy (LLLT), and 13 participants received a combination of both desensitizing techniques. Each participant represented self-control, where tooth sensitivity was measured before and after bleaching. The cold test was used to measure tooth sensitivity before bleaching, immediately after bleaching and after application of the proposed desensitizing technique. Then, a visual analogue scale (VAS) was used for re-assessment.

Results

The desensitizing methods exhibited a notable reduction in tooth sensitivity post-bleaching with no significant difference among the following therapies (p = 0.544).

Conclusion

All the employed desensitizing methods reduced post-bleaching sensitivity, with no significant differences among them. Thus, using one technique individually is enough for effort, time and cost savings.

Defocused high-power diode laser accelerates skin repair in a murine model through REDOX state modulation and reepithelization and collagen deposition stimulation

Skin wounds represent a burden in healthcare. Our aim was to investigate for the first time the effects of defocused high-power diode laser (DHPL) on skin healing in an animal experimental model and compare it with gold standard low-level laser therapy. Male Wistar rats were divided into 5 groups: Negative control; Sham; 0.1 W laser (L0.1 W); DHPL Dual 1 W (DHPLD1 W); and DHPL Dual 2 W (DHPLD2 W). Rats were euthanized on days 3, 5, 10, 14 and 21. Clinical, morphological, PicroSirus, oxidative stress (MDA, SOD and GSH) and cytokines (IL-1β, IL-10 and TNF-α) analyses were performed. A faster clinical repair was observed in all laser groups at D10 and D14. DHPLD1 W exhibited lower inflammation and better reepithelization compared to other groups at D10. DHPL protocols modulated oxidative stress by decreasing MDA and increasing SOD and GSH. Collagen maturation was triggered by all protocols tested and L0.1 W modulated cytokines release (IL-1β and TNF-α) at D3. In conclusion, DHPL, especially DHPL1 W protocol, accelerated skin healing by triggering reepithelization and collagen maturation and modulating inflammation and oxidative stress.

Dose-response and efficacy of low-level laser therapy on diabetic foot ulcers healing: Protocol of a randomized controlled trial

BACKGROUND

Current evidence shows that low-level laser therapy (LLLT) is an effective non-invasive and non-pharmacological strategy to treat diabetic foot ulcers (DFU). However, knowledge of parameterization efficacy remains unclear.

METHODS

This randomized, double-blind, controlled trial will be conducted at the Physical Therapy University Clinic. Eighty volunteers will be randomized into four groups. The control group will receive placebo LLLT + conventional treatment. The three active groups will receive 10 (G10), 8 (G8), or 4 J/cm² (G4) of GaAs 904 nm LLLT plus conventional treatment twice a week for 20 sessions. Conventional treatment involves cleaning and dressing the ulcers. The main outcome will be the area of ulcers and Wagner classification score. Assessments will take place before treatment, after 5 and 10 weeks of treatment, and in the third month after treatment, by a blinded evaluator.

IMPLICATIONS

This trial can potentially provide important information and assist in clinical decision-making regarding DFU treatment with LLLT.

TRIAL REGISTRATION

NCT04246814, registered 29th January 2020.

Photobiomodulation Therapy Improves Postoperative Pain and Edema in Third Molar Surgeries: A Randomized, Comparative, Double-Blind, and Prospective Clinical Trial

PURPOSE

Laser light has biological effects that can modulate inflammatory processes. Thus, this study aimed to evaluate the effects of photobiomodulation (PBM) therapy on pain, edema, and trismus after the extraction of retained third molars.

METHODS

A split-mouth, double-blind, randomized clinical trial (RCT) was conducted in 13 patients with similar bilateral third molars who received intraoral application PBM therapy at 4 points with a diode laser at 810 nm wavelength, 6 J (100 mW, 60 seconds/point) on 1 side (the PBM side); and laser irradiation simulation on the other side (SHAM side). The pain was assessed through visual analog scale (VAS) at 0, 12, 24, 48, and 72 hours, number of analgesic-relief (NAR), and mean time of first analgesic use; edema, through VAS, and linear facial measurements at 0, 24, 48, and 72 hours; and trismus, through the mouth opening measurements at 0, 24, 48, and 72 hours. The repeated-measures analysis was applied to assess the effect of the treatment, followed by Tukey's post hoc test for multiple comparisons (P < .05).

RESULTS

Thirteen patients (61.77% male and 38.63% female) with age of 24.16 ± 2.06 participated in this research. VAS showed that PBM controlled pain better (7.56 ± 6.25) than SHAM (32.25 ± 22.78) at 24 hours (P < .001) and 48 hours (19.47 ± 9.27 and 39.87 ± 4.21, respectively) (P = .011). VAS also showed that PBM controlled edema better (19.7 ± 13.27) than SHAM (32.38 ± 15.28) at 24 hours (P = .037) and 48 hours (19.47 ± 13.11 and 39.87 ± 22.77, respectively) (P = .002).

CONCLUSION

The PBM therapy in this study resulted in pain and edema reduction after third molar surgery and may be considered as adjuvant therapy after the surgical procedure.

Effect of low-level laser therapy on postoperative pain after single-visit root canal retreatment of mandibular molars: A randomized controlled clinical trial

AIM

To compare the effect of low-level laser therapy (LLLT) on postoperative pain after single-visit root canal retreatment on mandibular molars.

METHODOLOGY

This randomized controlled clinical trial included 36 patients referred to the Department of Endodontics, Islamic Azad University, Tehran, Iran. Healthy patients who required root canal retreatment on symptomatic first or second mandibular molars, with a PAI index score of 2 or 3, preoperative tooth and percussion pain of <56 mm on a 170-mm visual analogue scale (VAS) were included. After local anaesthesia using inferior alveolar nerve block followed by rubber dam isolation and access cavity preparation, the D RaCe retreatment system was used to remove the existing root filling material, and after canal negotiation and gaining patency, working length was determined with an apex locator. Further canal enlargement was carried out with size 35, 0.04 taper, and size 40, 0.04 taper RaCe rotary instruments and then canals were filled using laterally compacted gutta-percha points and AH Plus sealer. The patients were randomly assigned to treatment groups: In the LLLT group, a 980-nm diode laser set at 6.89 W/cm² energy density, 0.5 W power, and a tip diameter of 10 mm were activated from the buccal side on the mesial and distal root apices for 15 s. In the sham group, the laser handpiece was placed inside the patient's mouth at the same location, but the laser was not activated. Then patients were instructed to record their postoperative pain levels at 4, 8, 12 and 24 h and 2, 3 and 7 days after treatment on separate VAS scales. For data analysis, the independent sample t and the Mann-Whitney U tests were used. Nominal variables were analysed by using the chi-square test.

RESULTS

In the LLLT group, the most intense pain was reported 24 and 48 h post-treatment [mean (SD) = 0.22 (0.54) for both], whereas in the sham group, the most intense pain level was observed 4 h post-treatment [mean (SD) = 0.78 (0.80)]. At the 4-h interval, pain intensity was significantly lower in the LLLT group (p = .016).

CONCLUSIONS

Low-level laser therapy reduced postoperative pain after single-visit root canal retreatment of mandibular molars only four hours following the procedure.

Effect of photobiomodulation on post-operative symptoms in teeth with asymptomatic apical periodontitis treated with foraminal enlargement: A randomized clinical trial

AIM

To assess the efficacy of photobiomodulation in reducing post-operative symptoms and use of analgesics in teeth with asymptomatic apical periodontitis treated with foraminal enlargement in a single visit.

METHODOLOGY

This prospective double-blind, controlled, superiority, randomized clinical trial enrolled 70 patients requiring root canal treatment of one single-rooted tooth with asymptomatic apical periodontitis. The participants were randomized into one of the following two groups: 35 patients in the control group (C.G) - root canal treatment with foraminal enlargement, without any additional treatment and 35 patients in the photobiomodulation group (PBM.G) - root canal treatment with foraminal enlargement associated with photobiomodulation (antimicrobial photodynamic therapy and low-level laser therapy). The outcome variables were post-operative pain, tenderness, oedema and the use of analgesics. Pain intensity was measured using a visual analogue scale (recorded every day for 7 days, then the 14th and 30th days after root canal treatment). Facial oedema was assessed subjectively by two independent evaluators using photographs taken by one of the researchers at 48 h, 72 h and 7 days after the procedures. Data were tabulated and analysed using the Mann-Whitney U, Chi-Square, Fisher`s Exact, Student T and Ordinal Logistic Regression by Generalized Estimating Equations tests in SPSS software.

RESULTS

There were no significant differences in post-operative pain and tenderness between the groups at any observation period (p > .05). Photobiomodulation (beta = -0.77 / p = .01), time (beta = -0.23 / p < .01), and male gender (beta = -1.20 / p < .01) were associated with decreased post-operative pain. Only time (beta: -0.10; p < .01) and male gender (beta: -1.04; p < .01) were associated with decreased tenderness. For oedema and use of analgesics, there was no difference between the groups (p > .05).

CONCLUSIONS

Photobiomodulation had no significant effect on post-operative pain, tenderness, oedema and the use of analgesics after root canal treatment with foraminal enlargement, in single-rooted teeth treated in a single visit. Register of Clinical Trials: NCT03704857. Research Ethics Committee: no 2.353.996 / CAAE 74185417.9.0000.5626.

Photobiomodulation therapy promotes the ATP-binding cassette transporter A1-dependent cholesterol efflux in macrophage to ameliorate atherosclerosis

Atherosclerosis is a chronic inflammatory disease related to a massive accumulation of cholesterol in the artery wall. Photobiomodulation therapy (PBMT) has been reported to possess cardioprotective effects but has no consensus on the underlying mechanisms. Here, we aimed to investigate whether PBMT could ameliorate atherosclerosis and explore the potential molecular mechanisms. The Apolipoprotein E (ApoE)^−/− mice were fed with western diet (WD) for 18 weeks and treated with PBMT once a day in the last 10 weeks. Quantification based on Oil red O‐stained aortas showed that the average plaque area decreased 8.306 ± 2.012% after PBMT (P < .05). Meanwhile, we observed that high‐density lipoprotein cholesterol level in WD + PBMT mice increased from 0.309 ± 0.037 to 0.472 ± 0.038 nmol/L (P < .05) compared with WD mice. The further results suggested that PBMT could promote cholesterol efflux from lipid‐loaded primary peritoneal macrophages and inhibit foam cells formation via up‐regulating the ATP‐binding cassette transporters A1 expression. A contributing mechanism involved in activating the phosphatidylinositol 3‐kinases/protein kinase C zeta/specificity protein 1 signalling cascade. Our study outlines that PBMT has a protective role on atherosclerosis by promoting macrophages cholesterol efflux and provides a new strategy for treating atherosclerosis.

Combination of strontium chloride and photobiomodulation in the control of tooth sensitivity post-bleaching: A split-mouth randomized clinical trial

Objective

This split-mouth randomized controlled clinical trial assessed the effect of 10% strontium chloride in combination with photobiomodulation (PBM) for the control of tooth sensitivity (TS) post-bleaching.

Methods

The upper/lower, right and left quadrants of fifty volunteers were randomized and allocated to four groups (n = 25): PLACEBO—placebo gel + simulation of PBM; Placebo + PBM; STRONTIUM—10% strontium chloride + simulation of PBM; and PBM + STRONTIUM—10% strontium chloride + PBM. All groups received tooth bleaching treatment with 35% hydrogen peroxide. For the PBM treatment, the laser tip was positioned in the apical and cervical regions of the teeth bleached in the respective hemi-arch. The laser system was operated in continuous mode, using 1.7 J of energy. A dose of 60 J/cm² was applied to each point for 16 seconds under 808 nm near-infrared light (100mW of power), with a point area of 0.028 cm². TS was assessed during a 21-day follow-up, using the modified visual analogue scale.

Results

In the intragroup assessment, the Friedman test indicated that PBM + STRONTIUM promoted the greatest reduction in TS after the second week of treatment (p ≤ 0.05). The Wilcoxon-Mann-Whitney test indicated that the groups Placebo + PBM, STRONTIUM, and STRONTIUM + PBM did not differ statistically (p ≥ 0.05) in the first and third weeks of treatment The group PLACEBO exhibited the greatest TS in the first three days after each bleaching session.

Conclusion

The combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, the combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, it did not differ from the individual use of Placebo + PBM or STRONTIUM groups assessed after 21 days of follow-up.

Effects of Physical Stimulation in the Field of Oral Health

Physical stimulation has been widely used in clinical medicine and healthcare due to its noninvasiveness. The main applications of physical stimulation in the oral cavity include laser, ultrasound, magnetic field, and vibration, which have photothermal, cavitation, magnetocaloric, and mechanical effects, respectively. In addition, the above four stimulations with their unique biological effects, which can play a role at the gene, protein, and cell levels, can provide new methods for the treatment and prevention of common oral diseases. These four physical stimulations have been used as important auxiliary treatment methods in the field of orthodontics, implants, periodontal, dental pulp, maxillofacial surgery, and oral mucosa. This paper systematically describes the application of physical stimulation as a therapeutic method in the field of stomatology to provide guidance for clinicians. In addition, some applications of physical stimulation in specific directions are still at the research stage, and the specific mechanism has not been fully elucidated. To encourage further research on the oral applications of physical stimulation, we elaborate the research results and development history of various physical stimuli in the field of oral health.

Effect of low-level laser therapy on postoperative endodontic pain: An updated systematic review

OBJECTIVE

To evaluate the influence of low-level laser therapy (LLLT) on postoperative pain after endodontic treatment.

METHODS

The PICOS strategy was used to identify randomized clinical trials comparing low-level laser therapy and mock laser therapy to manage postoperative pain after endodontic treatment, retreatment, and endodontic surgery. An electronic search was performed in MEDLINE through PubMed, Web of Science, LILACS, Scopus and Cochrane Library, OpenGrey and Google Scholar. Quality assessment was performed using the Cochrane Collaboration's tool for assessing the risk of bias. The quality of evidence was rated on the basis of the GRADE approach.

RESULTS

Twelve studies were included in the qualitative synthesis. Within the 12 studies, 7 articles were classified as "low risk of bias," 4 studies were considered "unclear risk of bias" and 1 study was considered "high risk of bias." Six studies evaluated the postoperative pain after primary root canal treatment, two studies after root canal retreatment and four after periapical surgery. Most of the studies reported significantly less postoperative pain after LLLT in different time periods; two studies found no differences. The certainty of evidence was classified as low and very low to treatment / retreatment and endodontic surgery, respectively.

CONCLUSIONS

Based on the limited quality evidence, most of the included studies reported significantly less postoperative pain after LLLT. However, the lack of standardization in laser parameters, use of medications and the certainty of evidence classified as low and very low indicate the need for further studies.

Photobiomodulation invigorating collagen deposition, proliferating cell nuclear antigen and Ki67 expression during dermal wound repair in mice

The present investigation focuses on understanding the role of photobiomodulation in enhancing tissue proliferation. Circular excision wounds of diameter 1.5 cm were created on Swiss albino mice and treated immediately with 2 J/cm² and 10 J/cm² single exposures of the Helium-Neon laser along with sham-irradiated controls. During different days of healing progression (day 5, day 10, and day 15), the tissue samples upon euthanization of the animals were taken for assessing collagen deposition by Picrosirius red staining and cell proliferation (day 10) by proliferating cell nuclear antigen (PCNA) and Ki67. The positive influence of red light on collagen synthesis was found to be statistically significant on day 10 (P < 0.01) and day 15 (P < 0.05) post-wounding when compared to sham irradiation, as evident from the image analysis of collagen birefringence. Furthermore, a significant rise in PCNA (P < 0.01) and Ki67 (P < 0.05) expression was also recorded in animals exposed to 2 J/cm² when compared to sham irradiation and (P < 0.01) compared to the 10 J/cm² treated group as evidenced by the microscopy study. The findings of the current investigation have distinctly exhibited the assenting influence of red laser light on excisional wound healing in Swiss albino mice by augmenting cell proliferation and collagen deposition.

Effects of the Association between Photobiomodulation and Hyaluronic Acid Linked Gold Nanoparticles in Wound Healing

Healing is the process responsible for restoring the integrity of the body's internal or external structures when they rupture. Photobiomodulation (PBM) stands out as one of the most efficient resources in the treatment of epithelial lesions, as well as hyaluronic acid (HA), which has been emerging as a new molecule for the treatment of dermal and epidermal lesions. The biological application of gold nanoparticles (GNPs) shows promising results. This study aimed to investigate the possible anti-inflammatory and antioxidant effects of the association between PBM and GNPs-linked HA in an epithelial lesion model. Fifty Wistar rats were randomly distributed in the Control Group (CG); (PBM); (PBM + HA); (PBM + GNPs); (PBM + GNPs-HA). The animals were anesthetized, trichotomized, and induced to a surgical incision in the dorsal region. Topical treatment with HA (0.9%) and/or GNPs (30 mg/kg) occurred daily associated with 904 nm laser irradiation, dose of 5 J/cm², which started 24 h after the lesion and was performed daily until the seventh day. The levels of proinflammatory (IL1 and TNFα), anti-inflammatory (IL10 and IL4) and growth factors (FGF and TGFβ) cytokines and oxidative stress parameters were evaluated, besides histological analysis through inflammatory infiltrate, fibroblasts, new vessels, and collagen production area. Finally, for the analysis of wound size reduction, digital images were performed and subsequently analyzed by the IMAGEJ software. The treated groups showed a decrease in proinflammatory cytokine levels and an increase in anti-inflammatory cytokines. TGFβ and FGF levels also increased in the treated groups, especially in the combination therapy group (PBM + GNPs-HA). Regarding the oxidative stress parameters, MPO, DCF, and Nitrite levels decreased in the treated groups, as well as the oxidative damage (Carbonyl and Thiol groups). In contrast, antioxidant defense increased in the groups with the appropriate therapies proposed compared to the control group. Histological sections were analyzed where the inflammatory infiltrate was lower in the PBM + GNPs-HA group. The number of fibroblasts was higher in the PBM and PBM + HA treated groups, whereas collagen production was higher in all treated groups. Finally, in the analysis of the wound area contraction, the injury group presented a larger area in cm² compared to the other groups. Taken together, these results allow us to observe that the combination of PBM + GNPs-HA optimized the secretion of anti-inflammatory cytokines, proliferation and cell differentiation growth factors, and made an earlier transition to the chronic phase, contributing to the repair process.

Effect of Photobiomodulation Therapy (660 nm) on Wound Healing of Rat Skin Infected by Staphylococcus

Objective: To assess the impact of photobiomodulation (PBM) therapy on healing of infected wounds and document the microscopic findings throughout the recovery process. Background: Previous studies have suggested that PBM accelerates wound healing and reduces inflammation and pain. However, the ideal protocol and ultimate value of PBM treatment for infected wounds are controversial. Materials and methods: Eight-month-old male rats were randomly divided into the control group, the nonirradiation group, or the irradiation group. A 1 cm diameter skin excision was made. The wounds of the nonirradiated and irradiated rats were inoculated with a suspension of Staphylococcus aureus. We then performed 7 days of PBM therapy at a wavelength of 660 nm for 35 min/day. On day 8, the rats were sacrificed for histological assessment. Sections were stained with hematoxylin and eosin, Masson trichrome, and a proliferating cell nuclear antigen (PCNA) kit. Defect diameter was calculated using the Visus Image Analysis System. Results: The irradiated group had more epithelial cells and richer granulation tissue compared to those in the other groups. The irradiation group had a significantly smaller defect size than the nonirradiation group (p < 0.01) and the control group (p < 0.05). The amount of collagen was highest in the irradiation group and was graded as 3, 2, and 3+ in the control, nonirradiation, and irradiation groups, respectively. The percentage of PCNA in the control group was significantly lower than that in the other two groups (p < 0.05). Conclusions: PBM therapy (660 nm) promoted cell proliferation and collagen synthesis, thereby improving the wound healing response to an S. aureus infection.

The Combination of Antimicrobial Photodynamic Therapy and Photobiomodulation Therapy for the Treatment of Palatal Ulcers: A Case Report

Introduction: One of the unexpected side effects of the Haas type palatal expander is ulcers progressing to necrotic lesions in the palatal area due to poor hygiene. The use of antibiotic therapy is mandatory. However, long periods of healing/pain and the need for a systemic host response with the aid of metabolization, especially in children, are issues that should be taken into account in the management of this type of injury. Since phototherapy modalities (antimicrobial photodynamic therapy [aPDT] and photobiomodulation therapy [PBMT]) are able to enhance and accelerate the healing process and reduce the bacterial load, this case report aimed to describe the use of the above-mentioned therapies to treat palatal ulcers occurring during orthodontic expansion. Case Report: The patient, a 10-year-old boy, with a chief complaint of bleeding and continuous pain in the region of his expander was verified on a follow-up visit. After a dental examination, the expander was removed and two necrotic lesions which were in contact with the acrylic part of the tooth-tissue expander were found in the palatal region. The proposal was to use one aPDT session with methylene blue followed by 4 sessions of PBMT with a red laser diode. On the 5th day, reorganized tissue was verified, with the absence of bleeding, swelling, and pain. On the 20th day of follow-up, the area showed no signs of inflammation, healthy tissue without any pathological clinical symptoms, and complete wound healing. Conclusion: The concomitant use of PBMT and aPDT therapies may be considered feasible as an adjunct treatment to manage palatal ulcers resulting from the incorrect use of tooth-tissue types of expanders.

Experimental models and methods for cutaneous wound healing assessment

Wound healing studies are intricate, mainly because of the multifaceted nature of the wound environment and the complexity of the healing process, which integrates a variety of cells and repair phases, including inflammation, proliferation, reepithelialization and remodelling. There are a variety of possible preclinical models, such as in mice, rabbits and pigs, which can be used to mimic acute or impaired for example, diabetic and nutrition-related wounds. These can be induced by many different techniques, with excision or incision being the most common. After determining a suitable model for a study, investigators need to select appropriate and reproducible methods that will allow the monitoring of the wound progression over time. The assessment can be performed by non-invasive protocols such as wound tracing, photographic documentation (including image analysis), biophysical techniques and/or by invasive protocols that will require wound biopsies. In this article, we provide an overview of some of the most often needed and used: (a) preclinical/animal models including incisional, excisional, burn and impaired wounds; (b) methods to evaluate the healing progression such as wound healing rate, wound analysis by image, biophysical assessment, histopathological, immunological and biochemical assays. The aim is to help researchers during the design and execution of their wound healing studies.

Effects of phonophoresis with diclofenac linked gold nanoparticles in model of traumatic muscle injury

The use of nanotechnology for administering drugs is a recent development that presents promising results. Therapeutic Pulsed Ultrasound (TPU) is one such therapeutic option and is widely used for treating soft tissue lesions. Thus, the objective of this study was to investigate the therapeutic effect of phonophoresis using diclofenac (DC) linked to gold nanoparticles (GNPs) in the skeletal muscle of rats used as a model of traumatic muscular injury. Wistar rats were divided into eight groups (N = 10): Sham, Muscle injury (MI), MI + TPU, MI + DC, MI + GNPs, MI + TPU + DC, MI + TPU + GNPs, and MI + TPU + DC-GNPs. The traumatic injury was performed in the gastrocnemius with a single direct traumatic impact via an injuring press. The animals received daily treatment for 5 consecutive days with TPU and gel with DC and/or GNPs. Two hours after the last treatment session, animals were euthanized and the gastrocnemius muscle surgically removed for histological and biochemical analysis. The groups exposed to some therapies (MI + TPU + DC, MI + TPU + GNPs and MI + TPU + DC-GNPs) showed reduced levels of pro-inflammatory cytokines, whereas an increase in anti-inflammatory cytokine levels was observed in the group exposed to all therapies combined (MI + TPU + DC-GNPs). Reactive species production and protein damage resulting from oxidative damage was lower for the group exposed to all tested therapies had lower production. Lower protein damage was also observed in the TPU + GNPs group. The group that underwent all tested therapies combined showed a significant increase in antioxidants compared to the MI group. During histological analysis, the MI group showed large amounts of cell infiltration and centralized nuclei, whereas the MI + TPU + DC-GNPs group showed structural improvements. Pain levels in the MI + TPU + DC-GNPs group were lower than those of the MI group. We believe that the association of TPU with DC linked to GNPs decreases the inflammation caused by traumatic muscle injury and accelerates tissue repair.

Effects of transcranial photobiomodulation and methylene blue on biochemical and behavioral profiles in mice stress model

The effectiveness of transcranial photobiomodulation (tPBM) and methylene Blue (MB) in treating learning and memory impairments is previously reported. In this study, we investigated the effect of tPBM and MB in combination or alone on unpredictable chronic mild stress (UCMS)-induced learning and memory impairments in mice. Fifty-five male BALB/c mice were randomly allocated to five groups: control, laser sham + normal saline (NS), tPBM + NS, laser sham + MB, and tPBM + MB. All groups except the control underwent UCMS and were treated simultaneously for 4 weeks. Elevated plus maze (EPM) was used to evaluate anxiety-like behaviors. Novel object recognition (NOR) test and Barnes maze tests were used to evaluate learning and memory function. The serum cortisol and brain nitric oxide (NO), reactive oxygen species (ROS), total antioxidant capacity (TAC), glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels were measured by spectrophotometric methods. Behavioral tests revealed that UCMS impaired learning and memory, and treatment with PBM, MB, and their combination reversed these impairments. Levels of NO, ROS, SOD activity in brain, and serum cortisol levels significantly increased while brain GPx activity and total antioxidant capacity significantly decreased in the sham + NS animals when compared with the controls. A significant improvement was observed in treatment groups due to reversion of the aforementioned molecular analysis caused by UCMS when it was compared with control levels. Both tPBM and MB in combination or alone have significant therapeutic effects on learning and memory impairments in UCMS-received animals.

Effects of Different Protocols of Low-Level Laser Therapy on Collagen Deposition in Wound Healing

The low-level laser has proven successful in stimulating the production of collagen in wound healing assays. However, diversity has been observed in the protocols used. This work has evaluated the effects of three protocols of low-level laser therapy (LLLT) in the healing of open wounds in rats. Standard-sized wounds of 1 cm2 were performed with a scalpel in the middorsal region of 60 male Wistar rats weighing 225±25 g, and they were assigned into four groups (n=15): CTR (non-irradiated animals), LT1 (20 J/cm2 daily), LT2 (16 J/cm2 daily) and LT3 (20 J/cm2 daily). After 7, 14 and 21 days, five animals/day were euthanized and the wounds analyzed histologically. Data were subjected to normality analysis of distribution using Shapiro-Wilk test. Gaussian data were analyzed using ANOVA and Bonferroni tests whereas non-Gaussian data were analyzed using Kruskal-Wallis and Dunn tests, considering significant p values less than 0.05. The LLLT in all protocols reduced the inflammation and collagen deposition increased significantly (p<0.05). However, LT2 showed the highest levels of collagen in all phases of the study (p<0.05) induced faster replacement of immature collagen III by mature collagen I in the early stages of repair and early collagen remodeling promoted by providing better organization architectural beams deposited. It was concluded that all protocols induced an increase in collagen scar. However, the protocol 2 (16 J /cm2, daily application) promoted the most significant increases in collagen deposition, accelerated maturation of collagen and showed the best architecture of the final fibrous scarring.

Effects of photobiomodulation on mitochondria of brain, muscle, and C6 astroglioma cells

The purpose of this study was to investigate the effect of different doses of photobiomodulation (PBM) on mitochondrial respiratory complexes and oxidative cellular energy metabolic enzymes in the mitochondria of brain, muscle, and C6 glioma cells after different time intervals. C6 cells were irradiated with an AlGaInP laser at 10, 30, and 60 J/cm² for 20, 60, and 120 s, respectively. After irradiation, the cells were maintained in serum-free Dulbecco's Modified Eagle's medium for 24 h, and biochemical measurements were made subsequently. Mitochondrial suspensions from adult rat skeletal muscles/brains were irradiated with an AlGaInP laser at the abovementioned doses. In one group, the reaction was stopped 5 min after irradiation and in the other 60 min after irradiation. Both the C6 cells that received the doses of 10 and 30 J/cm² showed increased complex I activity; the cells that were irradiated at 30 J/cm² showed increased hexokinase activity. Five minutes after the introduction of PBM of the muscle mitochondria (at 30 and 60 J/cm²), the activity of complex I increased, while the activity of complex IV increased only at 60 J/cm². One hour after the laser session, complex II activity increased in the cells treated with 10 and 60 J/cm²; however, complex IV activity showed an increase in all PBM groups. In brain mitochondria, 5 min after irradiation only the activity of complex IV increased in all PBM groups. One hour after the laser session, complex II activity increased at 60 J/cm², and complex IV activity increased for all PBM groups when compared to controls. PBM could increase the activity of respiratory chain complexes in an apparently dose- and time-dependent manner.

The Anti-Inflammatory and Anti-Oxidant Mechanisms of the Keap1/Nrf2/ARE Signaling Pathway in Chronic Diseases

Oxidative stress is defined as an imbalance between production of free radicals and reactive metabolites or [reactive oxygen species (ROS)] and their elimination by through protective mechanisms, including (antioxidants). This Such imbalance leads to damage of cells and important biomolecules and cells, with hence posing a potential adverse impact on the whole organism. At the center of the day-to-day biological response to oxidative stress is the Kelch-like ECH-associated protein 1 (Keap1) - nuclear factor erythroid 2-related factor 2 (Nrf2)- antioxidant response elements (ARE) pathway, which regulates the transcription of many several antioxidant genes that preserve cellular homeostasis and detoxification genes that process and eliminate carcinogens and toxins before they can cause damage. The redox-sensitive signaling system Keap1/Nrf2/ARE plays a key role in the maintenance of cellular homeostasis under stress, inflammatory, carcinogenic, and pro-apoptotic conditions, which allows us to consider it as a pharmacological target. Herein, we review and discuss the recent advancements in the regulation of the Keap1/Nrf2/ARE system, and its role under physiological and pathophysiological conditions, e.g. such as in exercise, diabetes, cardiovascular diseases, cancer, neurodegenerative disorders, stroke, liver and kidney system, etc. and such.

Does laser therapy improve the wound healing process after tooth extraction? A systematic review

Laser therapy could amplify the oral wound healing process by stimulating cell regeneration after injury, attenuating pain, and modulating the immune system. The purpose of this systematic review was to evaluate whether the application of laser therapy improved alveolar healing after tooth extractions. Eight electronic databases were screened: MedLine (PubMed), The Cochrane Library, Web of Science, Scopus, Lilacs, Ibecs, Scielo, and BBO. Three reviewers independently assessed the title and abstracts of potentially relevant studies. Only clinical trials and animal experiments that evaluated the wound healing effect of laser therapy after tooth extraction were included. A total of 16 studies fulfilled all criteria, thus 8 animal experiments and 8 clinical trials were included. Different types of laser were evaluated, such as CO₂ , GaAlAs, Nd:YAG, Diode Laser, HeNe, and High-frequency Pulsed Diode Laser. Although HF, Diode and GaAs lasers were able to enhance wound healing process in clinical studies, four trials and one animal experiment showed no improvement in wound healing with laser therapy after tooth extractions. In general, the current available evidence in the literature showed that laser therapy improved the wound healing process, but these findings were limited to the type of laser applied and its specific settings. Further well-designed and randomized controlled trials are needed to support a benefit effect of using laser therapy after tooth extraction. PROSPERO registration number: CRD42014007509 (2014).

Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling post-bleaching tooth sensitivity: clinical, randomized, controlled, double-blind, and split-mouth study

OBJECTIVES

To evaluate the effect of photobiomodulation with low-level laser therapy (PBM-LLLT) combined with 5% potassium nitrate (KNO₃) on controlling tooth sensitivity (TS) after in-office tooth bleaching.

MATERIALS AND METHODS

Fifty volunteers were selected based on the inclusion and exclusion criteria and were randomly allocated into four groups: G1 (control): placebo gel application, 35% hydrogen peroxide bleaching (HP35) and mock PBM-LLLT without light emission; G2: placebo gel application, bleaching with HP35 and PBM-LLLT; G3: application of KNO₃, bleaching with HP35 and mock PBM-LLLT; and G4: application of KNO₃, bleaching with HP35 and PBM-LLLT. A pain assessment questionnaire was used to evaluate TS during the 21 days of treatment. The Friedman test was used for intragroup analysis, and the Wilcoxon and Mann-Whitney tests were used for intergroup comparisons.

RESULTS

The intragroup evaluation showed significant differences among the evaluation times in all groups (p ≤ 0.05). The highest pain sensitivity levels were recorded on the 1st, 8th, and 15th days. In G1, TS manifested for up to 3 days after each bleaching session, while G2, G3, and G4 presented TS only on the days of the bleaching sessions. Intergroup analysis showed that TS manifestation differed significantly between G1 and the other groups (p ≤ 0.05) but did not differ significantly among G2, G3, and G4 (p ≥ 0.05).

CONCLUSION

PBM-LLLT and KNO₃ are effective at reducing pain sensitivity after tooth bleaching, but no synergistic effect between these treatments was observed for the different evaluation periods.

CLINICAL RELEVANCE

The effect of PBM-LLLT combined with KNO₃ on post-bleaching tooth sensitivity is similar to their individual use alone.

Photobiomodulation in the Prevention of Tooth Sensitivity Caused by In-Office Dental Bleaching. A Randomized Placebo Preliminary Study

OBJECTIVE

Analyze the effect of photobiomodulation in the prevention of tooth sensitivity after in-office dental bleaching.

BACKGROUND DATA

Tooth sensitivity is a common clinical consequence of dental bleaching. Therapies for prevention of sensitivity have been investigated in literature.

MATERIALS AND METHODS

This study was developed as a randomized, placebo blind clinical trial. Fifty patients were selected (n = 10) and randomly divided into five groups: (1) control, (2) placebo, (3) laser before bleaching, (4) laser after bleaching, and (5) laser before and after bleaching. Irradiation was performed perpendicularly, in contact, on each tooth during 10 sec per point in two points. The first point was positioned in the middle of the tooth crown and the second in the periapical region. Photobiomodulation was applied using the following parameters: 780 nm, 40 mW, 10 J/cm², 0.4 J per point. Pain was analyzed before, immediately after, and seven subsequent days after bleaching. Patients were instructed to report pain using the scale: 0 = no tooth sensitivity, 1 = gentle sensitivity, 2 = moderate sensitivity, 3 = severe sensitivity.

RESULTS

There were no statistical differences between groups at any time (p > 0.05). More studies, with others parameters and different methods of tooth sensitivity analysis, should be performed to complement the results found.

CONCLUSIONS

Within the limitation of the present study, the laser parameters of photobiomodulation tested in the present study were not efficient in preventing tooth sensitivity after in-office bleaching.

Effect of low-level laser therapy combined with 5000 parts per million fluoride dentifrice on postbleaching sensitivity: A clinical, randomized, and double-blind study

OBJECTIVE

The aim of this double-blind, randomized, controlled clinical study was to assess the efficacy of low-level laser therapy (LLLT) combined with 5000 ppm fluoride dentifrice on postbleaching sensitivity in teeth exposed to 35% hydrogen peroxide for four weeks.

MATERIALS AND METHODS

Twenty-five volunteers were evaluated using the split-mouth model in which the right and left maxillary/mandibular quadrants were randomized and allocated to one of two groups: GPLACEBO, in which the laser tip was positioned without the emission of light (placebo effect) + 5000 ppm sodium fluoride, or GLASER, which comprised LLLT + 5000 ppm sodium fluoride. For both groups, LLLT and placebo were used before bleaching, whereas fluoride was applied after bleaching. LLLT was applied at two points: on the central cervical and medial regions of the incisors, canines, and premolars in the corresponding hemi-arch. At each point, 60 J/cm² was applied for 16 seconds with an irradiance of 3.75 W/cm² using the therapeutic infrared device. To assess tooth sensitivity, a modified visual analogue scale was used after an evaporative stimulus, and a daily pain questionnaire was also applied.

RESULTS

The Wilcoxon and Friedman tests demonstrated a significant difference in the incidence of sensitivity pain between GPLACEBO and GLASER (P ≤ .05), with different evaluation times.

CONCLUSION

Teeth treated with laser therapy in combination with the topical use of sodium fluoride at each bleaching session demonstrated less sensitivity compared with the application of sodium fluoride only.

CLINICAL SIGNIFICANCE

The use of a low-level laser therapy in combination with topical use of sodium fluoride improves symptoms of dentin sensitivity at each bleaching session.

Aging of lymphoid organs: Can photobiomodulation reverse age-associated thymic involution via stimulation of extrapineal melatonin synthesis and bone marrow stem cells?

Thymic atrophy and the subsequent reduction in T-cell production are the most noticeable age-related changes affecting lymphoid organs in the immune system. In fact, thymic involution has been described as "programmed aging." New therapeutic approaches, such as photobiomodulation (PBM), may reduce or reverse these changes. PBM (also known as low-level laser therapy) involves the delivery of non-thermal levels of red or near-infrared light that are absorbed by mitochondrial chromophores, in order to prevent tissue death and stimulate healing and regeneration. PBM may reverse or prevent thymic involution due to its ability to induce extrapineal melatonin biosynthesis via cyclic adenosine monophosphate (AMP) or NF-kB activation, or alternatively by stimulating bone marrow stem cells that can regenerate the thymus. This perspective puts forward a hypothesis that PBM can alter thymic involution, improve immune functioning in aged people and even extend lifespan.

Effect of Low-Level Laser Irradiation on the Function of Glycated Catalase

Introduction: The aim of this work is to evaluate the effect of low-level laser irradiation (LLLI), by lasers with different wavelengths, on glycated catalase enzyme in vitro experimentally. Methods: This is done by measuring the activity and structure properties of glycated catalase enzyme. The structure properties were evaluated with circular dichroism (CD) and fluoroscopy methods. Three continuous wave (CW) lasers in the visible spectrum (λ =450, 530, 638 nm) and a 100-ns pulsed laser in the infrared spectrum (λ =905 nm) were chosen for comparison. For the infrared laser, same effects have been investigated for different energy doses. The effect of photon energy (hυ) at different wavelengths was measured on activity, CD, and fluoroscopy properties of catalase, and compared with the control group (samples without irradiation). The energy intensity of laser should not exceed 0.1 J/cm² . Experiments were performed on glycated catalase between 2 to 16 weeks after glycation of catalase. The LLLI effect was also investigated on the samples, by comparing the catalase activity, CD and fluoroscopy for different wavelengths. Results: Our results indicated, the decrease in catalase activity as a function of glycation time (weeks) for all samples, and a slight increase on its activity by different laser wavelengths irradiation for any fixed period of glycation time. Finally, the catalase activity has been increased as the laser's photon energy (hυ) intensified. More specifically, the blue laser (λ =450 nm) had the most and the red laser (λ =638 nm) had the least effect, and the green laser (λ =530 nm) had the medium effect on catalase activity as well. Furthermore, pulsed laser had an additional effect by increasing energy dosage. Conclusion: As we expected in all experiments, an increase in the catalase activity was coincident with a decrease in the catalase fluoroscopy and CD parameters.

Effect of low-level laser therapy on tooth-related pain and somatosensory function evoked by orthodontic treatment

Low-level laser therapy (LLLT) may have an effect on the pain associated with orthodontic treatment. The aim of this study was to evaluate the effect of LLLT on pain and somatosensory sensitization induced by orthodontic treatment. Forty individuals (12–33 years old; mean ± standard deviations: 20.8 ± 5.9 years) scheduled to receive orthodontic treatment were randomly divided into a laser group (LG) or a placebo group (PG) (1:1). The LG received LLLT (810-nm gallium-aluminium-arsenic diode laser in continuous mode with the power set at 400 mW, 2 J·cm^–2) at 0 h, 2 h, 24 h, 4 d, and 7 d after treatment, and the PG received inactive treatment at the same time points. In both groups, the non-treated side served as a control. A numerical rating scale (NRS) of pain, pressure pain thresholds (PPTs), cold detection thresholds (CDTs), warmth detection thresholds (WDTs), cold pain thresholds (CPTs), and heat pain thresholds (HPTs) were tested on both sides at the gingiva and canine tooth and on the hand. The data were analysed by a repeated measures analysis of variance (ANOVA). The NRS pain scores were significantly lower in the LG group (P = 0.01). The CDTs, CPTs, WDTs, HPTs, and PPTs at the gingiva and the PPTs at the canine tooth were significantly less sensitive on the treatment side of the LG compared with that of the PG (P < 0.033). The parameters tested also showed significantly less sensitivity on the non-treatment side of the LG compared to that of the PG (P < 0.043). There were no differences between the groups for any quantitative sensory testing (QST) measures of the hand. The application of LLLT appears to reduce the pain and sensitivity of the tooth and gingiva associated with orthodontic treatment and may have contralateral effects within the trigeminal system but no generalized QST effects. Thus, the present study indicated a significant analgesia effect of LLLT application during orthodontic treatment. Further clinical applications are suggested.

Repeated applications of low-level laser therapy during and after orthodontic procedures could help reduce pain and discomfort. Many orthodontic patients experience pain in the hours and days following treatment, which impacts on treatment participation. Wenjing Chen at Nanjing Medical University and co-workers assessed whether low-level laser therapy (LLLT) can reduce pain and sensitivity in teeth and surrounding tissues. They divided 40 patients into two groups; one was given repeated LLLT in the hours and days following procedures, while the other group received a placebo course. They tested both groups for sensitivity to stimuli including heat and pressure, in the mouth and on the hands. LLLT significantly reduced pain in the mouth relative to the placebo group. No differences were found in tests on the hands, suggesting LLLT works as a targeted analgesia.

Photobiomodulation mechanisms in the kinetics of the wound healing process in rats

OBJECTIVES

The healing process of cutaneous lesions is considered a complex event divided into distinct and overlapping phases, which responds satisfactorily to photobiomodulation (PBM). PBM is indicated as a therapeutic resource capable of assisting tissue repair. The present study aimed to analyze the kinetics of cutaneous wounds healing process after application of the GaAlAs laser for treating wounds on the dorsum of rats.

MATERIALS AND METHODS

This study was approved by the Animal Ethics Committee of UFSCar. The animals were divided into 2 groups (n = 10); control group (CG) used 0.9% saline solution and the laser group (LG) used GaAlAs, 670 nm continuous pulse, 30 mW power, 14.28 J/cm² energy density, irradiating 1 point per wound for 30s, totaling 15 consecutive days of treatment. Samples were collected on the 4th, 11th and 16th days for histological analysis of HE, Picrosirius-Red, immunohistochemistry (Collagen1, TNF-α, VEGF). Statistical analyzes used the one-way ANOVA test for intra and inter group evaluations, and the Tukey post-test. Level of significance was set at p < 0.05.

RESULTS

The histopathological analysis (HE) showed a statistically significant difference for lower values of inflammatory infiltrate in LG versus CG on the 16th day; and for the increase of collagen in the 11th and 16th days of treatment. There was a statistically significant difference in the increase of VEGF on the 11th day for LG; decrease of TNF-α on the 4th and 11th day for LG, and increase of collagen type 1 on the 4th and 16th days for LG. The birefringence analysis of the percentage of collagen fibers presented on the 11th day of treatment revealed a greater quantity and significant statistical difference. Collagen fibers showed improved organization and arrangement on the 11th day for LG.

CONCLUSION

Our results show that PBM is effective in helping the kinetics of the cutaneous wound healing process in rats and promotes the necessary stimuli for the satisfactory evolution of healing process, ultimately leading to structurally desirable tissue.

Effects of low-level laser therapy following surgical extraction of the lower third molar with objective measurement of swelling using a three-dimensional system

The aim of the present study was to evaluate and compare the effects of single- and two-dose low-level laser therapy (LLLT) on the postoperative swelling, trismus and pain of patients undergoing extraction of impacted mandibular third molars. In addition, edema was volumetrically measured with a 3dMD face system. A total of 45 patients were randomly divided into three treatment groups (15 patients in each group) as follows: Group 1, receiving routine management with ice application and serving as the control group; Group 2, receiving a single dose of LLLT immediately following surgery; and Group 3, receiving two doses of LLLT, immediately following surgery and on day 2 after surgery. In the present study, a gallium-aluminum-arsenide (0.3 W, 40 sec, 4 J/cm²) diode laser device was applied extraorally at the insertion point of the masseter muscle. The trismus, pain level and facial swelling of the patients were evaluated. The visual analog scale (VAS) was used to examine the pain degree, while a 3dMD face photogrammetric system was used to evaluate the volumetric alterations of the swelling. The results indicated no statistically significant differences in the mean swelling or trismus among the three groups. The mean VAS measurements did not differ significantly among the groups at postoperative day 2; however, significantly reduced VAS values were observed in Group 2 compared with Group 1 at postoperative day 7 (P<0.05). The present study demonstrated that, although single-dose or two-dose LLLT had beneficial effects on the swelling, trismus and pain level, a significant reduction was only observed in the pain level at postoperative day 7.

The effects of transcutaneous low-level laser therapy on the skin healing process: an experimental model

We aim to evaluate the action of transcutaneous laser in the initial wound healing process. The use of low-level laser therapy (LLLT) has proven to be effective on inflammatory modulation and wound healing. The trial was performed on five groups of rats, through a dorsal incision. All groups received treatment on auricular artery. Groups 1 and 3 were treated with transcutaneous LLLT over a period of 15 min. Groups 2 and 4 received one and two inactive laser applications (placebo), respectively. Group 5 was the control one. Blood samples were collected 2 h after the last application of LLLT so that cytokine levels could be measured by ELISA. Tissue fragments were harvested for morphometric, histomorphometric, and RT-qPCR analyses. The morphometric analysis revealed a greater decrease in the wounded area in G1 when compared with G2, whereas in G3, the improvement in the area was greater when compared with G4. Finally, the histomorphometric analysis showed that G1 was the group closer to G5 in terms of collagen fiber count. G2 and G4 had higher amounts of collagen fibers than G5 while G3 had a lower quantity. The use of the transcutaneous LLLT in the current study influenced the wound healing process.