Effect of Low Intensity Helium-Neon (He-Ne) Laser Irradiation on Diabetic Wound Healing Dynamics

Comparative Investigation of Photobiomodulation in Diabetes-Impaired Alveolar Bone Healing: A Histomorphometrical and Molecular Study

Objective: Diabetes mellitus is increasing worldwide. Photobiomodulation (PBM) is proposed as a therapeutic method in various medical concerns. This study aimed to compare the effects of PBM at the wavelengths of 660, 808, or 660 + 808 nm on alveolar bone healing in diabetic rats. Methods: Bilateral maxillary first molars were extracted from diabetic Wistar rats (n = 36). Right-sided sockets were treated by an In-Ga-Al-P laser at 660 nm (7.2 J/cm2, 24 s; DM660), Ga-Al-As laser at 808 nm (7 J/cm2, 14 s; DM808), or a combination of these two sets (DM-dual) (n = 12). Left sides served as controls. On days 7 or 14, specimens were assigned for histomorphometric or real-time PCR analysis of runt-related transcription factor 2, osteocalcin, collagen I, and vascular endothelial growth factor expression. Results: Irradiated sockets of groups DM-808 and DM-dual showed a significant increase in bone tissue and blood vessel establishment as compared to DM-660. Further, group DM-dual exhibited the least amount of fibrotic tissue as compared to the other groups. Conclusions: Within our study limits, the present experiment suggested PBM at 808 nm, alone or combined with 660 nm irradiation, could promote alveolar bone healing, along with minimal fibrosis induction, in diabetic rats.

Diabetes in spotlight: current knowledge and perspectives of photobiomodulation utilization

Introduction

Diabetes is a global health concern characterized by chronic hyperglycemia resulting from insulinopenia and/or insulin resistance. The rising prevalence of diabetes and its associated complications (ulcers, periodontitis, healing of bone defect, neuropathy, retinopathy, cardiopathy and nephropathy) necessitate innovative therapeutic approaches. Photobiomodulation (PBM), involves exposing tissues and cells to low-energy light radiation, leading to biological effects, largely via mitochondrial activation.

Methods

This review evaluates preclinical and clinical studies exploring the potential of PBM in diabetes and its complications, as well all clinical trials, both planned and completed, available on ClinicalTrials database.

Results

This review highlights the variability in PBM parameters across studies, hindering consensus on optimal protocols. Standardization of treatment parameters and rigorous clinical trials are needed to unlock PBM's full therapeutic potential. 87 clinical trials were identified that investigated PBM in diabetes mellitus (with 5,837 patients planned to be treated with PBM). Clinical trials assessing PBM effects on diabetic neuropathy revealed pain reduction and potential quality of life improvement. Studies focusing on wound healing indicated encouraging results, with PBM enhancing angiogenesis, fibroblast proliferation, and collagen density. PBM's impact on diabetic retinopathy remains inconclusive however, requiring further investigation. In glycemic control, PBM exhibits positive effects on metabolic parameters, including glucose tolerance and insulin resistance.

Conclusion

Clinical studies have reported PBM-induced reductions in fasting and postprandial glycemia without an increased hypoglycemic risk. This impact of PBM may be related to its effects on the beta cells and islets in the pancreas. Notwithstanding challenges, PBM emerges as a promising adjunctive therapy for managing diabetic neuropathy, wound healing, and glycemic control. Further investigation into its impact on diabetic retinopathy and muscle recovery is warranted.

Insights into the mechanisms of diabetic wounds: pathophysiology, molecular targets, and treatment strategies through conventional and alternative therapies

Diabetes mellitus is a prevalent cause of mortality worldwide and can lead to several secondary issues, including DWs, which are caused by hyperglycemia, diabetic neuropathy, anemia, and ischemia. Roughly 15% of diabetic patient's experience complications related to DWs, with 25% at risk of lower limb amputations. A conventional management protocol is currently used for treating diabetic foot syndrome, which involves therapy using various substances, such as bFGF, pDGF, VEGF, EGF, IGF-I, TGF-β, skin substitutes, cytokine stimulators, cytokine inhibitors, MMPs inhibitors, gene and stem cell therapies, ECM, and angiogenesis stimulators. The protocol also includes wound cleaning, laser therapy, antibiotics, skin substitutes, HOTC therapy, and removing dead tissue. It has been observed that treatment with numerous plants and their active constituents, including Globularia Arabica, Rhus coriaria L., Neolamarckia cadamba, Olea europaea, Salvia kronenburgii, Moringa oleifera, Syzygium aromaticum, Combretum molle, and Myrtus communis, has been found to promote wound healing, reduce inflammation, stimulate angiogenesis, and cytokines production, increase growth factors production, promote keratinocyte production, and encourage fibroblast proliferation. These therapies may also reduce the need for amputations. However, there is still limited information on how to prevent and manage DWs, and further research is needed to fully understand the role of alternative treatments in managing complications of DWs. The conventional management protocol for treating diabetic foot syndrome can be expensive and may cause adverse side effects. Alternative therapies, such as medicinal plants and green synthesis of nano-formulations, may provide efficient and affordable treatments for DWs.

In Vitro Effect of Photobiomodulation Therapy with 980 nm Diode Laser on Gene Expression of Key Regulators of Bone Remodeling by Human Periodontal Ligament Cells under Mild Orthodontic Forces

This study investigated the effect of photobiomodulation (PBM) with 980 nm diode laser as monotherapy and in combination with compressive and tensile orthodontic forces on expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), sclerostin (SOST) and periostin (POSTN), by human periodontal ligament cells. Isolated cells were cultured and subjected to either tensile (10% elongation) or compressive forces (25 g cm-2 ) for 24 and 48 h. Subsequently, the cells received PBM (100 mW power, 3 or 6 J cm-2 energy density) immediately after load cycle. RT-PCR was applied to assess the genes expression. Data were analyzed by one-way ANOVA, followed by post hoc Tukey test (P ≤ 0.05). We found that PBM in combination with orthodontic forces led to upregulation of bone resorption genes (RANKL and SOST) at the pressure side and their downregulation at the tension side. The expression of osteogenic genes (OPG and POSTN) increased at the tension side and decreased at the pressure side. PBM alone did not affect gene expression. In conclusion, these findings suggest that this PBM protocol may be effective in enhancement of the gene expression in favor of bone remodeling acceleration that should be confirmed in future animal and human studies.

Dose-response relationship of photobiomodulation therapy and oxidative stress markers in healing dynamics of diabetic neuropathic ulcers in Wistar rats

Purpose

Diabetic foot ulcers are reported to be the most expensive complications of diabetes, with high morbidity and mortality rates. If the necessary care is not provided for the wound to heal, the individual may end up amputating the affected feet. Photobiomodulation therapy is a promising non-pharmacological treatment option for wound healing. The objective of the present study is to establish a dose-response relationship between photobiomodulation therapy and oxidative stress markers in the healing dynamics of diabetic neuropathic ulcers in Wistar rats.

Methodology

Diabetic neuropathy was induced in 126 Albino Wistar rats. An excisional wound of an area of 2cm2 was made on the neuropathy-induced leg. Photobiomodulation therapy of dosages 4, 6, 8, 10, 12, and 15 J/cm2 of wavelengths 655 and 808 nm was irradiated. The control group animals were kept un-irradiated. The outcome measures were assessed during wound healing's inflammatory, proliferative and remodelling phases.

Results

In the experimental group, animals treated with photobiomodulation therapy at doses of 4, 6, and 8 J/cm2 showed better wound healing dynamics. Photobiomodulation therapy modulated the reactive oxygen species and antioxidant levels, thereby improving the oxidative status of the wound.

Conclusion

Photobiomodulation therapy of dosages 4, 6, and 8 J/cm2 is effective and is a promising adjuvant modality in treating diabetic neuropathic ulcers. There was a strong dose-response relationship in the experimental groups treated with 4, 6 and 8 J/ cm2.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-01157-2.

Effect of Photobiomodulation on the Incidence of Alveolar Osteitis and Postoperative Pain following Mandibular Third Molar Surgery: A Double-Blind Randomized Clinical Trial

The current study aimed to evaluate the effectiveness of photobiomodulation therapy for the prevention of incidence of alveolar osteitis (AO) and postoperative pain following third molar surgery. In this double-blind clinical trial, the impacted teeth of patients having bilateral impacted mandibular third molars were surgically extracted; for each participant, one socket was randomly assigned to receive photobiomodulation treatment, the other received sham treatment. 660 nm 200 mW CW was applied at a distance of ~1cm to 4 points on the occlusal area of extraction socket (beam area at the tissue ~0.64 cm² , 312.5 mW cm^-2 , 1J, 1.6 J cm^-2 ). Also, 810 nm 200 mW CW was applied at tissue surface at three points on the buccal and three points on the lingual gingiva, for 15 s (400 mW cm^-2 , 3 J, 6 J cm^-2 ). There was a statistically meaningful difference in AO frequency between the two groups, and the photobiomodulation group showed lower AO frequency compared with the sham PBM treatment (P-value = 0.035). According to the findings of this study, photobiomodulation therapy reduced the incidence of AO following surgical removal of impacted mandibular third molars. The incidence of AO typically occurs 3-7 days post-extraction, and our results suggest that PBM treatment within the 7 days could help reduce the risk of AO development.

Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications

The development of a painless, non-invasive, and faster way to diabetic wound healing is at the forefront of research. The complexity associated with diabetic wounds makes it a cause for concern amongst diabetic patients and the world at large. Irradiation of cells generates a photobiomodulatory response on cells and tissues, directly causing alteration of cellular processes and inducing diabetic wound repair. Photobiomodulation therapy (PBMT) using red and near-infrared (NIR) wavelengths is being considered as a promising technique for speeding up the rate of diabetic wound healing, eradication of pain and reduction of inflammation through the alteration of diverse cellular and molecular processes. This review presents the extent to which the potential of red and NIR wavelengths have been harnessed in PBMT for diabetic wound healing. Important research challenges and gaps are identified and discussed, and future directions mapped out. This review thus provides useful insights and strategies into improvement of PBMT, including its acceptance within the global medical research community.

Effect of photobiomodulation therapy on inflammatory cytokines in healing dynamics of diabetic wounds: a systematic review of preclinical studies

CONTEXT

Delayed wound healing in diabetes mellitus (DM) is due to the overlapping phases of the healing process. The prolonged inflammation and altered levels of inflammatory cytokines lead to deformed cell proliferation. Photobiomodulation alleviates the expression of inflammatory cytokines and promotes tissue repair, thereby restoring the wound healing process.

OBJECTIVE

To find out the effect of photobiomodulation therapy (PBMT) in the healing dynamics of diabetic wounds with particular emphasis on interleukin-6, interleukin-1β, and tumour necrosis factor-α.

METHODS

Scientific databases searched using keywords of the population: DM, intervention: PBMT, and outcomes: inflammatory cytokines.

RESULTS

We have included five preclinical studies in the present systematic review for qualitative analysis. These studies evaluated the effect of PBMT at different wavelengths, dosage, and time on wound healing in DM.

CONCLUSIONS

The systematic review concludes that PBMT regulates inflammatory cytokines levels, enhances cell proliferation, and migration, thereby improving the wound healing properties.

Biostimulative effect of laser on growth of mesenchymal stem/stromal cells in vitro

Introduction

Human adipose tissue-derived mesenchymal stem/stromal cells (hAT-MSCs) are multipotent stromal cells with a high potential application in tissue engineering and regenerative medicine. Laser irradiation of the place where the cells were implanted can stimulate their proliferation, increase the secretion of growth factors and thus increase the therapeutic effect.

Aim

To evaluate the influence of two lasers: Er:YAG and diode on the growth of hAT-MSCs in vitro.

Material and methods

hAT-MSCs were isolated from human subcutaneous adipose tissue. Immunophenotype of hAT-MSCs was confirmed by flow cytometry. Multipotency of hAT-MSCs was confirmed by differentiation into adipogenic, osteogenic and chondrogenic lineages. hAT-MSCs were irradiated with Er:YAG laser (wavelength 2940 nm, frequency 5, 10 Hz, doses: 0.1–1.2 J/cm²) for 2 s and 4 s and diode laser (wavelength 635 nm and doses: 1–8 J/cm²) for 5, 10, 20, 30 and 40 s. Cell viability was analysed 24 h after the exposure using MTT assay.

Results

Growth stimulation of hAT-MSCs after 5 Hz Er:YAG laser exposure, 0.1 J/cm² dose for 4 s and 0.3 J/cm² dose for 4 s was shown in comparison with the control group. Significant growth stimulation of hAT-MSCs after diode laser irradiation in doses of 1–4 J/cm² was demonstrated compared to the control group.

Conclusions

The presented results indicate that both lasers, Er:YAG and diode can be used to stimulate stem/stromal cell growth in vitro. The biostimulative effect of laser therapy on stromal cells may be used in the future in aesthetic dermatology in combined laser and cell therapy.

Technological Advances in Wound Treatment of Exotic Pets

Although most research about the use of technological advances for wound healing was performed in laboratory animals but oriented to human medicine, recent technological advances allowed its application not only to small animals but also to exotic pets. This article reviews the literature available about some of these techniques (negative wound pressure therapy, photobiomodulation [laser therapy], electrical stimulation therapy, therapeutic ultrasonography, hyperbaric oxygen therapy), and other advances in wound management (skin expanders, xenografts, and bioengineered autologous skin substitutes) in exotic pet species.

The Clinical Evaluation of the Effects of Low-Level Laser Therapy on the Donor and Recipient Sites of the Free Gingival Graft: A Case Series

Introduction: Free gingival grafting is among the most foreseeing procedures for increasing the zone of keratinized attached gingiva and enhancing soft tissue around the teeth and dental implants. Nowadays low-level laser therapy (LLLT) is a promising approach in providing patients with more pleasing results in terms of esthetics and comfort. This study aims to investigate the effects of LLLT on gingival recessions treated with free gingival graft (FGG). Methods: This case series was conducted on 12 individuals requiring a bilateral gingival graft in the mandibular region. There was a 30-day interval between the two operations. The test side was selected randomly and irradiated by a low-level laser (LLL) just before surgery. The patients did not know which side was irradiated. LLLT was applied to the donors' as well as recipients' site immediately after the operation and 48 hours later. The patients were instructed to record their post-operative pain in a visual analogue scale (VAS) 3 and 24 hours and 7 days after the surgical procedure. The clinical photographs were taken immediately and 30 days after surgical treatment were graded by three experienced periodontists for color matching to adjacent tissues. Results: Ten individuals could finish the study. The test group presented significantly better shade matching and wound healing at the palatal donor site on days 7, 14 and 21. There was a significant reduction in post-operative pain after 24 hours (P = 0.007). No statistically significant difference was found between both groups in terms of clinical periodontal indices. Conclusion: LLLT could reduce post-operative pain 24 hours after surgical treatment. Furthermore, the application of LLLT could improve the donors' site healing and the recipients' site color matching.

Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review

We have systematically assessed published cell studies and animal experimental reports on the efficacy of selected biophysical energies (BPEs) in the treatment of diabetic foot ulcers. These BPEs include electrical stimulation (ES), pulsed electromagnetic field (PEMF), extracorporeal shockwave (ECSW), photo energies and ultrasound (US). Databases searched included CINAHL, MEDLINE and PubMed from 1966 to 2018. Studies reviewed include animal and cell studies on treatment with BPEs compared with sham, control or other BPEs. Information regarding the objective measures of tissue healing and data was extracted. Eighty-two studies were eventually selected for the critical appraisal: five on PEMF, four each on ES and ECSW, sixty-six for photo energies, and three about US. Based on the percentage of original wound size affected by the BPEs, both PEMF and low-level laser therapy (LLL) demonstrated a significant clinical benefit compared to the control or sham treatment, whereas the effect of US did not reveal a significance. Our results indicate potential benefits of selected BPEs in diabetic wound management. However, due to the heterogeneity of the current clinical trials, comprehensive studies using well-designed trials are warranted to confirm the results.

Therapeutic efficacy of early photobiomodulation therapy on the zones of stasis in burns: An experimental rat model study

This study aimed to investigate the role of photobiomodulation therapy in preventing zones of stasis in burn wounds. We hypothesized that photobiomodulation therapy could promote tissue formation and release of nitric oxide (NO), and reduce inflammatory responses, thereby dilating local microvessels, reducing necrosis and apoptosis. Thirty rats were randomly divided into control group (CG) and laser group (LG). The zone of stasis was formed by applying a brass comb to the skin resulting in four rectangular burns separated by three unburned interspaces. The left side was laser wound (LW), while the right side was shielded wound (SW). The LW of LG was immediately subjected to photobiomodulation therapy, followed by once-daily 30-minutes photobiomodulation therapy sessions. Skin ultrasound and Doppler angiography analyses were used to evaluate the statuses of the zones of stasis at 1, 24, and 96 hours after injury. Harvested burn wound tissue was subjected to hematoxylin-eosin staining and HMGB1, caspase 3, and thrombomodulin immunohistochemistry, and the contents of NO and TNF-α were measured in stasis tissue. Thrombomodulin, HMGB1, and caspase 3 immunohistochemistry revealed significantly lower positive staining rates in the LW of LG rats relative to the others at 96 hours (p < 0.05), as well as a significantly higher skin blood flow relative to the others (p < 0.05). The NO content was significantly higher in the LW of LG, compared with other wounds, at 24 and 96 hours after injury (p < 0.05). The TNF-α level was significantly lower in the LW of LG than in other wounds at 96 hours (p < 0.05). Early, local photobiomodulation therapy can effectively ameliorate injury progression in the zone of stasis. However, these beneficial effects are limited to the directly irradiated sites.

Laser photobiomodulation in pressure ulcer healing of human diabetic patients: gene expression analysis of inflammatory biochemical markers

Pressure ulcers (PU) are wounds located mainly on bone surfaces where the tissue under pressure suffers ischemia leading to cellular lesion and necrosis , its causes and the healing process depend on several factors. The aim of this study was evaluating the gene expression of inflammatory/reparative factors: IL6, TNF, VEGF, and TGF, which take part in the tissue healing process under effects of low-level laser therapy (LLLT). In order to perform lesion area analysis, PUs were photographed and computer analyzed. Biochemical analysis was performed sa.mpling ulcer border tissue obtained through biopsy before and after laser therapy and quantitative real-time PCR (qRT-PCR) analysis. The study comprised eight individuals, mean age sixty-two years old, and sacroiliac and calcaneous PU, classified as degree III and IV according to the National Pressure Ulcer Advisory Panel (NPUAP). PUs were irradiated with low-level laser (InGaAIP, 100 mW, 660 nm), energy density 2 J/cm², once a day, with intervals of 24 h, totaling 12 applications. The lesion area analysis revealed averaged improvement of the granulation tissue size up to 50% from pre- to post-treatment. qRT-PCR analysis revealed that IL6 values were not significantly different before and after treatment, TNF gene expression was reduced, and VEFG and TGF-β gene expression increased after treatment. After LLLT, wounds presented improvement in gross appearance, with increase in factors VEFG and TGF-β, and reduction of TNF; despite our promising results, they have to be analyzed carefully as this study did not have a control group.

The influence of low-intensity He-Ne laser on the wound healing in diabetic rats

The low-level laser irradiation at certain wavelengths is reported to facilitate the healing process of diabetic wounds. Thus, this study carried out to look for the suitable laser parameters that could speed up the healing process. Fourteen healthy male and female rats were used in which a circular wound with a diameter of 2.5 ± 0.2 cm was created on the dorsum in each rat after injected them with alloxan to induced diabetic. They have been divided into two groups: control group (N = 7) and study group (N = 7) to conduct the study. He-Ne laser with a wavelength of 632.8 nm at power density of 4.0 mW/cm² was used to irradiate the study group for five times a week until the wound healed (closed) completely, while the control group was kept untreated. The results showed that the laser-treated group healed (wounds were totally closed) faster compared to the control group. In numbers, the laser-treated group healed on average at the 21st day (0.0 ± 0.0 cm) (P ≤ 0.005), whereas the control group healed after 40 days or even 60 days in some cases (sample no. 2). This confirms that laser promotes the tissue repair process of diabetic wounds and reduces the healing period to the half.

The Effect of Low Level Laser Therapy on Direct Pulp Capping in Dogs

Introduction: The aim of this study was to determine the histologic effect of low level laser therapy (LLLT) with or without the use of mineral trioxide aggregate (MTA) on exposed pulp tissues of dogs. Methods: Twenty-five premolar teeth in three healthy mature dogs were randomly divided into five groups. In group 1, the pulp tissue was capped with MTA. In groups 2 and 3, before capping with MTA, the exposure site was irradiated by low power lasers at 630 nm (20 mW, 150 seconds, 7.5 J/cm²) and 810 nm (peak power 80 W, average power 50 mW, 1500 Hz, 50 seconds, 6.25 J/cm²) wavelengths, respectively. In groups 4 and 5, the exposure site was irradiated similar to that described in groups 2 and 3, but the pulp tissue was covered by gold foil instead of MTA. After 2 months, the animals were sacrificed and the samples were prepared for histologic evaluation. Results: There were differences in pulpal response and dentinal barrier formation among the study groups. The morphology of pulpal tissue and the integrity of dentinal barrier and formation of odontoblastic layer were more favorable in the first three groups. The occurrence of extensive and intense inflammation and necrosis was more frequent in groups 4 and 5. Conclusion: Under the conditions used in this study, the presence of MTA as a pulp capping material was more important than laser therapy in the success of direct pulp capping (DPC) treatment. MTA proved to be an effective material either alone or in combination with laser irradiation in vital pulp therapy.

Laser therapy in wound healing associated with diabetes mellitus - Review

OBJECTIVE

To determine the most effective parameter in healing wounds related to diabetes mellitus, as well as the most widely used type of laser.

METHODOLOGY

consisted of bibliographic searching the databases Bireme, SciELO, PubMed/Medline and Lilacs by using the keywords related to the topic. Were selected from these keywords, papers discussing the use of laser on wounds associated with diabetes, published in the period 2005-2014, in Portuguese or English.

RESULTS

After analyzing the research, 12 studies consistent with the theme were selected.

CONCLUSION

Based on this review, the studies that showed more satisfactory results in healing diabetic wounds were those who applied energy densities in the range of 3-5 J/cm2, power densities equal to or below 0.2 W/cm2 and continuous emission. The He-Ne laser with a wavelength of 632.8 nm was used more often.

The effect of low-level helium-neon laser on oral wound healing

BACKGROUND

The effectiveness of low power lasers on incisional wound healing, because of conflicting results of previous studies, is uncertain. Therefore, the aim of this study was to evaluate the effects of low-level helium-neon (He-Ne) laser irradiation on wound healing in rat's oral mucosa.

MATERIALS AND METHODS

Sixty-four standardized incisions were carried out on the buccal mucosa of 32 male Wistar divided into four groups of eight animals each. Each rat received two incisions on the opposite sides of the buccal mucosa by a steel scalpel. On the right side (test side), a He-Ne laser (632 nm) was employed on the incision for 40 s. Laser radiation was used just in 1(st) day, 1(st) and 2(nd) day, 1(st) and 3(rd) day, and continuous 3 days in groups of A, B, C, and D of rats, respectively. The left side (control side) did not receive any laser. Histological processing and hematoxylin and eosin staining were done on tissue samples after 5 days. Wilcoxon and Kruskal-Wallis tests were used for statistical analysis.

RESULTS

Histological analysis showed that the tissue healing after continuous 3 days on the laser irradiated side was better than the control side, but there was no difference between the two sides in each groups (P > 0.05).

CONCLUSION

This study showed that He-Ne laser had no beneficial effects on incisional oral wound healing particularly in 5 days after laser therapy. Future research in the field of laser effects on oral wound healing in human is recommended.

Comparison of the effect of low level laser therapy with alvogyl on the management of alveolar osteitis

Background

This study investigated the efficacy of low level laser therapy (LLLT) for managing alveolar osteitis (AO).

Material and Methods

Sixty patients with alveolar osteitis of mandibular third molars were randomly divided into three groups. In group 1, socket irrigation was followed by alvogyl placement, and the treatment was repeated 48 hours later. In group 2, socket was irradiated with a low power red laser for 3 consecutive days (200 mW, 30 seconds on each of the buccal and lingual surfaces and 30 seconds at the middle of the socket, 6 J per area). The subjects in group 3 underwent treatment with a low power infrared laser with the same parameters as group 2. A visual analogue scale (VAS) was used to record the degree of pain at the morning (T0, before intervention) and at 6 (T1) and 12 (T2) hours later for 3 days.

Results

Pain was significantly lower in the alvogyl group than the other groups at T1 and T2 points on day 1 and at T0 and T1 points on day 2 (p<0.05). At T2 point on day 2 and on day 3, VAS became significantly lower in the red laser group compared to the other groups (p<0.05). The infrared laser was not more efficacious than the other groups at any of the treatment intervals, but it reduced VAS to an acceptable level.

Conclusions

LLLT displayed good results in this study for treatment of alveolar osteitis and should be further investigated as an alternative to alvogyl for AO management.

Key words: Low level laser, low power laser, therapy, alvogyl, dry socket, alveolar osteitis, mandibular third molar.

Effects of low-power light therapy on wound healing: LASER x LED

Several studies demonstrate the benefits of low-power light therapy on wound healing. However, the use of LED as a therapeutic resource remains controversial. There are questions regarding the equality or not of biological effects promoted by LED and LASER. One objective of this review was to determine the biological effects that support the use of LED on wound healing. Another objective was to identify LED´s parameters for the treatment of wounds. The biological effects and parameters of LED will be compared to those of LASER. Literature was obtained from online databases such as Medline, PubMed, Science Direct and Scielo. The search was restricted to studies published in English and Portuguese from 1992 to 2012. Sixty-eight studies in vitro and in animals were analyzed. LED and LASER promote similar biological effects, such as decrease of inflammatory cells, increased fibroblast proliferation, stimulation of angiogenesis, granulation tissue formation and increased synthesis of collagen. The irradiation parameters are also similar between LED and LASER. The biological effects are dependent on irradiation parameters, mainly wavelength and dose. This review elucidates the importance of defining parameters for the use of light devices.

Effect of equal daily doses achieved by different power densities of low-level laser therapy at 635 nm on open skin wound healing in normal and diabetic rats

BACKGROUND AND OBJECTIVE

Despite the fact that the molecular mechanism of low-level laser therapy (LLLT) is not yet known, the exploitation of phototherapy in clinical medicine and surgery is of great interest. The present study investigates the effects of LLLT on open skin wound healing in normal and diabetic rats.

MATERIALS AND METHODS

Four round full-thickness skin wounds on dorsum were performed in male adult nondiabetic (n = 24) and diabetic (n = 24) Sprague-Dawley rats. AlGaInP (635 nm, wavelength; 5 J/cm(2), daily dose) was used to deliver power densities of 1, 5, and 15 mW/cm(2) three times daily until euthanasia.

RESULTS

PMNL infiltration was lower in the irradiated groups (15 mW/cm(2)). The synthesis and organisation of collagen fibres were consecutively enhanced in the 5 mW/cm(2) and 15 mW/cm(2) groups compared to the others in nondiabetic rats. In the diabetic group the only significant difference was recorded in the ratio PMNL/Ma at 15 mW/cm(2). A significant difference in the number of newly formed capillaries in the irradiated group (5, 15 mW/cm(2)) was recorded on day six after injury compared to the control group.

CONCLUSION

LLLT confers a protective effect against excessive inflammatory tissue response; it stimulates neovascularization and the early formation of collagen fibres.

Photobiomodulation of surgical wound dehiscence in a diabetic individual by low-level laser therapy following median sternotomy

In this single case study, we attempt to outline the possible effect of low-level laser therapy (LLLT) on delayed wound healing and pain in chronic dehiscent sternotomy of a diabetic individual. The methods that were employed to evaluate changes pre and post irradiation were wound photography, wound area measurement, pressure ulcer scale of healing (PUSH), and visual analogue scale (VAS) for pain. After irradiation, proliferation of healthy granulation tissue was observed with decrease in scores of PUSH for sternal dehiscence and VAS for bilateral shoulders and sternal dehiscence. We found that LLLT irradiation could be a novel method of treatment for chronic sternal dehiscence following coronary artery bypass grafting, as it augments wound healing with an early closure of the wound deficit. Hence, this might be translated into an early functional rehabilitation and decreased pain perception of an individual following surgical complication.

Laserterapia e microcorrente na cicatrização de queimadura em ratos: terapias associadas ou isoladas?

Este estudo teve o objetivo de investigar se há diferenças entre as terapias associadas e isoladas do laser e microcorrentes no reparo de lesão por queimadura em ratos. Um total de 40 animais foi dividido aleatoriamente em quatro grupos: grupo controle (GC); grupo microcorrente (GM), grupo laser (GL) e grupo laser/microcorrente (GLM), tratados com laser associado a microcorrentes. Após lesões térmicas induzidas no dorso do animal, foi realizado um total de dez dias de tratamento. Amostras do tecido foram coletadas para estudo histopatológico semiquantitativo com Hematoxilina Eosina e Tricrômico de Masson. Foram utilizados os testes de Kruskal-Wallis e post-hoc de Dunn. Houve diferença significativa entre os grupos para a produção de fibroblastos (p=0,0003), colágeno (p=0,0153), neoangiogênese (p=0,0031) e anexos cutâneos (p=0,0004). Na análise histológica semiquantitativa, o GLM apresentou valores menores nos parâmetros histológicos de presença de colágeno, número de fibroblastos e anexos cutâneos (p<0,05) em relação às terapias isoladas, exceto para a neoangiogênese, cujos valores da terapia associada foram semelhantes aos grupos de terapia com modalidade única. Apesar do laser e da microcorrente separadamente terem efeitos benéficos para a cicatrização tecidual, a associação das modalidades parece ter diminuído a ação de reparo. No entanto, sugere-se que a associação destes recursos parece diminuir os efeitos do tratamento quando se comparam os grupos de modalidade única.

Photoactivation of bone marrow mesenchymal stromal cells with diode laser: effects and mechanisms of action

Mesenchymal stromal cells (MSCs) are a promising cell candidate in tissue engineering and regenerative medicine. Their proliferative potential can be increased by low-level laser irradiation (LLLI), but the mechanisms involved remain to be clarified. With the aim of expanding the therapeutic application of LLLI to MSC therapy, in the present study we investigated the effects of 635 nm diode laser on mouse MSC proliferation and investigated the underlying cellular and molecular mechanisms, focusing the attention on the effects of laser irradiation on Notch-1 signal activation and membrane ion channel modulation. It was found that MSC proliferation was significantly enhanced after laser irradiation, as judged by time lapse videomicroscopy and EdU incorporation. This phenomenon was associated with the up-regulation and activation of Notch-1 pathway, and with increased membrane conductance through voltage-gated K(+) , BK and Kir, channels and T- and L-type Ca(2+) channels. We also showed that MSC proliferation was mainly dependent on Kir channel activity, on the basis that the cell growth and Notch-1 up-regulation were severely decreased by the pre-treatment with the channel inhibitor Ba(2+) (0.5 mM). Interestingly, the channel inhibition was also able to attenuate the stimulatory effects of diode laser on MSCs, thus providing novel evidence to expand our knowledge on the mechanisms of biostimulation after LLLI. In conclusions, our findings suggest that diode laser may be a valid approach for the preconditioning of MSCs in vitro prior cell transplantation.

Collagen production in diabetic wounded fibroblasts in response to low-intensity laser irradiation at 660 nm

BACKGROUND

Collagen type I (Col-I) is a major component of the extracellular matrix and is important in wound healing processes. Several studies have shown that low-intensity laser irradiation (LILI) biostimulates Col-I synthesis both in vitro and in vivo. This study aimed to determine if LILI affects collagen production and related cellular responses in an in vitro diabetic wounded fibroblast model.

MATERIALS AND METHODS

This study was performed on isolated human skin fibroblasts. Different cell models (normal and diabetic wounded) were used. Cells were irradiated with 5 J/cm(2) at a wavelength of 660 nm and incubated for 48 or 72 h. Nonirradiated cells (0 J/cm(2)) were used as controls. Cellular viability (Trypan blue exclusion test), morphology (bright-field microscopy), proliferation [VisionBlue™ quick cell proliferation assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay], and Col-I (enzyme-linked immunoabsorbent assay) were assessed.

RESULTS

Diabetic wounded cells irradiated with 5 J/cm(2) at 660 nm showed a significant increase in cell migration, viability, proliferation, and collagen content.

CONCLUSIONS

This study shows that LILI stimulates Col-I synthesis in diabetic wound healing in vitro at 660 nm.

Anti-inflammatory effect of low-intensity laser on the healing of third-degree burn wounds in rats

Third-degree burn wounds are considered severe injuries because they destroy all the skin layers and may affect subcutaneous tissues, fasciae, muscles, and bones. To favor the healing process of the injured tissues, it is very useful to diminish the occurrence of the inflammatory process. The present study was aimed at comparing the effect of different energetic densities of AlGaInP laser on the inflammatory process and in the healing of third-degree burn wounds in Wistar rats. This study was approved by the Ethics Committee, in which 36 adult male rats were selected and suffered the induction of third-degree burn injury. These rats were divided as follows: group 1-control (treated with silver sulfadiazine), group 2-received energy density of 3 J/cm(2), and group 3-received energy density of 6 J/cm(2). All animals daily received an occlusive bandage with silver sulfadiazine and 8 % papain. The laser therapy was performed alternatively three times a week. The animals were evaluated on the 3rd, 7th, 14th, and 21st days after the initial lesion and euthanized for the macroscopic, histologic, and morphometric analysis. A higher production of collagen was observed at 7 days and a greater re-epithelialization at 21 days in group 3 (6 J/cm(2)). Furthermore, the latter when compared to the other groups presented macroscopically a better aspect of the scar at 21 days with more granulation tissue and fibrosis. We conclude that the AlGaInP laser used in dosages of 3 and 6 J/cm(2) favors the healing of third-degree burn wounds induced in rats.

DNA repair gene expression in biological tissues exposed to low-intensity infrared laser

Special properties of laser light have led to its usefulness in many applications in therapy. Excitation of endogenous chromophores in biotissues and generation of free radicals could be involved in its biological effects. DNA lesions induced by free radicals are repaired by base excision repair pathway. In this work, we evaluated the expression of APE1 and OGG1 genes related to repair of DNA lesions induced by free radicals. Skin and muscle tissues of Wistar rats were exposed to low-intensity infrared laser at different fluences and frequencies. After laser exposition of 1 and 24 h, tissue samples were withdrawn for total RNA extraction, cDNA synthesis, and evaluation of APE1 and OGG1 gene expression by quantitative polymerase chain reaction. Data obtained show that laser radiation alters the expression of APE1 and OGG1 mRNA differently in skin and muscle tissues of Wistar rats depending of the fluence, frequency, and time after exposure. Our study suggests that low-intensity infrared laser affects expression of genes involved in repair of DNA lesions by base excision repair pathway.

Closure of non-healing chronic ulcer in Klippel-Trenaunay syndrome using low-level laser therapy

A 69-year-old man diagnosed with Klippel-Trenaunay syndrome (KTS) reported to the physiotherapy outpatient clinic with the complaint of a non-healing ulcer over the right medial malleolus, for a 6-month duration, that was non-granulating and had moderate pus discharge with foul odour at initial assessment. There was a decrease in scores of the Pressure Ulcer Scale of Healing, a significant increase in granulation tissue, a decrease in the amount of discharge and foul odour along with complete closure of the chronic wound after irradiation with a light-emitting diode (LED). This is a novel case study analysing the possible effect of a helium-neon laser  and LEDs on non-healing chronic ulcers associated with KTS, where the complete closure of the chronic ulcer that was initially not responsive to standard medical care was observed.

Efficacy of low level laser therapy on wound healing in patients with chronic diabetic foot ulcers-a randomised control trial

Foot ulcers are serious complications of Diabetes Mellitus (DM) and are known to be resistant to conventional treatment. They may herald severe complications if not treated wisely. Electromagnetic radiations in the form of photons are delivered to the ulcers in laser form to stimulate healing. This study was conducted to evaluate the efficacy of Low Level Laser Therapy (LLLT) in diabetic ulcer healing dynamics. To determine mean percentage reduction of wound area in study and control groups.

SETTINGS

KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belgaum.

STUDY DESIGN

Randomized-Control Study.

METHODS

A total of 68 patients with Type 2 DM having Meggitt-Wagner Grade I foot ulcers of atleast more than 4 weeks duration, less than 6 × 6 cm(2) with negative culture were studied. Patients were randomized into two groups of 34 each. Patients in study group received LLLT with conventional therapy and those in control group were treated with conventional therapy alone. Healing or percentage reduction in ulcer area over a period of 15 days after commencement of treatment was recorded.

STATISTICAL ANALYSIS

Unpaired Student T Test and Mann Whitney U test. Mean age of the patients was 50.94 years in control group and 54.35 years in study group (p = 0.065). There was no significant difference between control and study group with respect to mean FBS and HbA1c levels (p > 0.05), suggesting no biochemical differences between two groups. Initial ulcer area was 2608.03 mm(2) in study group and 2747.17 mm(2) in control group (p = 0.361). Final ulcer area was 1564.79 mm(2) in study group and 2424.75 mm(2) in control group (p = 0.361). Percentage ulcer area reduction was 40.24 ± 6.30 mm(2) in study group and 11.87 ± 4.28 mm(2) in control group (p < 0.001, Z = 7.08). Low Level Laser Therapy is beneficial as an adjunct to conventional therapy in the treatment of diabetic foot ulcers (DFU).

Laser biomodulation of normal and neoplastic cells

This study was designed to determine the laser dose for the stimulation, zero-bioactivation, and inhibition of normal and neoplastic cells in vitro. The medical use of laser biomodulation has been occurring for decades in the area of tissue healing and inflammatory conditions. The potential to modulate the regeneration and differentiation of early cellular precursors by laser photons is a valuable endeavor searching for novel and efficient methods. A 35-mW HeNe (632.8-nm) laser and power density of 1.25 mW/cm(2) was used to irradiate tissue culture dishes seeded with 400 cells/dish of normal cells (CHO, CCL-226, 3 T3, and HSF) and neoplastic cells (EMT-6 and RIF-1). All cell lines were cultured using DMEM supplemented with 10% and 5% FBS, 2 mM glutamine and 100 U pen-strep antibiotic. Irradiation times of 16, 32, 48, 64, 80, 96, 112, 128, 144, and 160 s for three consecutive days to deliver cumulative doses of 60, 120, 180, 240, 300, 360, 420, 480, 540, and 600 mJ/cm(2) were done, respectively. Cell cultures were stained and colony-forming efficiency was determined. Data analysis was done using Student's t test, α = 0.05. A trend of stimulation, zero-bioactivation, and inhibition in all cell lines was observed except for CCL-226 which gave a pattern of inhibition, zero-bioactivation, and inhibition. The optimum biostimulatory dose was at 180 mJ/cm(2) and bioinhibitory doses were from 420-600 mJ/cm(2) cumulative doses. This study established the dose-dependency of cell growth to laser treatments, that the extent of cellular proliferation is influenced by the type of cells involved, and the risk when laser irradiation is performed on patients with undiagnosed neoplasms and during pregnancy. On the other hand, the ability of laser irradiation to regulate embryonic fibroblasts and human skin fibroblast in vitro suggests possible laser biomodulatory effects on embryonic and adult stem cells directed for tissue regeneration. Studies on the effects of light treatments exploring different laser parameters for the clonal expansion and differentiation of stem cells are recommended.

Uso combinado da laserterapia de baixa potência e da inibição da ciclooxigenase-2 na reepitelização de ferida incisional em pele de camundongos: um estudo pré-clínico

FUNDAMENTOS: A laserterapia de baixa potência e os inibidores seletivos da ciclooxigenase-2 (ICOX2) vem sendo muito utilizados para modular a resposta inflamatória, entretanto, os seus efeitos na reepitelização de feridas não são bem compreendidos. OBJETIVO: Avaliar os efeitos isolados e combinados da laserterapia de baixa potência e da ICOX2 na reepitelização de ferida incisional na pele de camundongos. MÉTODO: Foi induzida uma ferida de 1 cm no dorso de cada camundongo, que foram divididos em quatro grupos (N=20): Controle, Laserterapia, Tratados com celecoxib e Terapia conjugada. Os animais dos grupos celecoxib e Terapia conjugada foram tratados com celecoxib por 10 dias antes da incisão cutânea. As feridas experimentais foram irradiadas com laserterapia de baixa potência He-Ne (632nm, dose: 4J/cm2) em varredura, por 12 segundos durante três dias consecutivos nos grupos Laserterapia e Terapia conjugada. Os animais foram sacrificados no 3º dia de pós-operatório. Amostras das feridas foram coletadas e coradas (Tricromio de Masson) para análise histomorfométrica. RESULTADOS: Tanto o grupo Laserterapia, quanto o grupo celecoxib, mostrou aumento da reepitelização cutânea em relação ao grupo Controle, entretanto, o grupo Terapia conjugada não apresentou diferenças. Quanto à queratinização o grupo Laserterapia e Terapia conjugada apresentaram redução dos queratinócitos, comparados com o grupo Controle. CONCLUSÕES: Os resultados mostram que o uso da laserterapia de baixa potência e da ICOX2 isoladamente aumentam as células epiteliais, mas somente a laserterapia de baixa potência reduziu os queratinócitos cutâneos. O tratamento conjugado restabelece a reepitelização inata e dimunui a queratinização, embora ocorra uma acelerada contração da ferida com melhora na organização da ferida na pele de camundongos.

Laserterapia de baixa intensidade na expressão de colágeno após lesão muscular cirúrgica

A laserterapia é um procedimento utilizado em larga escala nas lesões musculoesqueléticas, devido as suas diversas propriedades, antiinflamatórias, cicatrizantes entre outras. Além disso, há tipos distintos de aparelhos de laser. Mesmo com os diversos modelos experimentais existentes na literatura, não há um consenso sobre a faixa de utilização, bem como o tipo de laser que promove melhor reparo no tecido muscular. Este estudo visa analisar os efeitos da laserterapia de baixa intensidade na expressão de colágeno após lesão muscular. Camundongos Swiss albinos (n=18) foram submetidos à lesão muscular cirúrgica e divididos em dois grupos, controle (C) e teste (T). Os animais foram submetidos a uma irradiação diária de 5 J/cm² pelos lasers AsGaAl 830 nm e AsGa 904 nm e, em diferentes tempos de sacrifício (7 e 14 dias). Os resultados não demonstraram diferença estatística significativa na expressão de colágeno em ambos os grupos analisados. Contudo, os dados apontam que a dose de 5 J/cm² do laser AsGa 904 nm promoveu maior deposição de fibras colágenas após 14 dias de tratamento, sugerindo que a terapia seja efetiva na síntese de colágeno. Outros estudos experimentais, em humanos, devem ser propostos para maiores inferências sobre os resultados do laser no tratamento da lesão muscular.

Low-intensity laser irradiation stimulates wound healing in diabetic wounded fibroblast cells (WS1)

BACKGROUND

Patients with diabetes suffer from slow-to-heal wounds, which often necessitate amputation. Low-intensity laser irradiation (LILI) has been shown to reduce the healing time in such patients. This study aimed to determine the effect of different wavelengths of LILI on cellular migration, viability, and proliferation in a wounded diabetic cell model.

METHODS

Diabetic wounded and unwounded human skin fibroblast cells (WS1) were irradiated at 632.8, 830, or 1,064 nm with 5 J/cm(2). Cellular morphology and migration were determined microscopically, while cellular viability was determined by ATP luminescence, and proliferation was determined by basic fibroblast growth factor expression and alkaline phosphatase activity.

RESULTS

Diabetic wounded cells irradiated at 1,064 nm showed a lesser degree of migration, viability, and proliferation compared to cells irradiated at 632.8 or 830 nm. Cells irradiated at 632.8 nm showed a higher degree of haptotaxis and migration as well as ATP luminescence compared to cells irradiated at 830 nm.

CONCLUSIONS

This study showed that LILI of diabetic wounded cells in the visible range (632.8 nm) was more beneficial to wound healing than irradiating the same cells to wavelengths in the infrared range. Cells irradiated at a longer wavelength of 1,064 nm performed worse.