Is there a protocol in experimental skin wounds in rats using low-level diode laser therapy (LLDLT) combining or not red and infrared wavelengths? Systematic review

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.

Effect of different low-level intensity laser therapy (LLLT) irradiation protocols on the osseointegration of implants placed in grafted areas

OBJECTIVE

To evaluate the effect of different protocols of low-level intensity laser therapy (LLLT) irradiation on the osseointegration of implants placed in grafted areas.

METHODOLOGY

84 rats were randomly allocated into six groups: DBB: defect filled with deproteinized bovine bone; HA/TCP: defect filled with biphasic ceramic of hydroxyapatite/β-tricalcium phosphate ; DBB-LI: defect filled with DBB and treated with LLLT after implant placement; HA/TCP-LI: defect filled with HA/TCP and treated with LLLT after implant placement; DBB-LIB: defect filled with DBB and treated with LLLT after graft procedure and implant placement; and HA/TCP-LIB: defect filled HA/TCP and treated with LLLT after graft procedure and implant placement. The bone defects were made in the tibia and they were grafted. After 60 days, the implants were placed. The rats were subsequently subjected to euthanasia 15 and 45 days after implant placement. The pattern of osseointegration and bone repair in the grafted area was evaluated by biomechanical, microtomographic, and histometric analyses. Furthermore, the expression of bone biomarker proteins was assessed.

RESULTS

The LLLT groups presented higher removal torque, mineralized tissue volume, and a greater degree of osseointegration, especially when LLLT was performed only after implant placement, and these findings were associated with higher expression of BMP2 and alkaline phosphatase.

CONCLUSION

LLLT performed on implants placed in grafted areas enhances the osseointegration process.

In Vitro Evidences of Different Fibroblast Morpho-Functional Responses to Red, Near-Infrared and Violet-Blue Photobiomodulation: Clues for Addressing Wound Healing

Although photobiomodulation (PBM) has proven promising to treat wounds, the lack of univocal guidelines and of a thorough understanding of light–tissue interactions hampers its mainstream adoption for wound healing promotion. This study compared murine and human fibroblast responses to PBM by red (635 ± 5 nm), near-infrared (NIR, 808 ± 1 nm), and violet-blue (405 ± 5 nm) light (0.4 J/cm2 energy density, 13 mW/cm2 power density). Cell viability was not altered by PBM treatments. Light and confocal laser scanning microscopy and biochemical analyses showed, in red PBM irradiated cells: F-actin assembly reduction, up-regulated expression of Ki67 proliferation marker and of vinculin in focal adhesions, type-1 collagen down-regulation, matrix metalloproteinase-2 and metalloproteinase-9 expression/functionality increase concomitant to their inhibitors (TIMP-1 and TIMP-2) decrease. Violet-blue and even more NIR PBM stimulated collagen expression/deposition and, likely, cell differentiation towards (proto)myofibroblast phenotype. Indeed, these cells exhibited a higher polygonal surface area, stress fiber-like structures, increased vinculin- and phospho-focal adhesion kinase-rich clusters and α-smooth muscle actin. This study may provide the experimental groundwork to support red, NIR, and violet-blue PBM as potential options to promote proliferative and matrix remodeling/maturation phases of wound healing, targeting fibroblasts, and to suggest the use of combined PBM treatments in the wound management setting.

Quality assessment of systematic reviews regarding the effectiveness of zygomatic implants: an overview of systematic reviews

Background

Oral rehabilitation of atrophic maxillae features high complexity, for which there are several therapeutic modalities reported on scientific literature. Zygomatic implant placement is a viable option that features low morbidity and allows immediate prosthetic loading. The purpose of the present study was to determine the methodological quality of systematic reviews that assessed the effectiveness of zygomatic implants placed in atrophic maxillae.

Material and Methods

Searches were conducted on Medline via Pubmed, LILACS, Dare Cochrane, Scopus, and Sigle via Open Grey up to June 2019.

Results

Seven systematic reviews were eligible for Overview and comprised a total of 2313 patients, 4812 zygomatic implants, and a 96,72% success rate. Common surgical complications, in decreasing order, were: maxillary sinusitis, peri-implant mucositis, prosthetic fracture, and infections. Methodological quality was assessed using the AMSTAR 2 tool, which revealed that six systematic reviews showed critically low methodological quality and one review was assessed as of low methodological quality.

Conclusions

Zygomatic implants seem to be an adequate option for atrophic maxilla rehabilitation, however, new studies with a higher methodological rigor are needed to provide more reliable results to professionals and patients undergoing this modality of oral rehabilitation.

Key words:Zygomatic Implants, dental Implants, complications, oral rehabilitation.

Effectiveness of low-level laser therapy for oral mucositis prevention in patients undergoing chemoradiotherapy for the treatment of head and neck cancer: A systematic review and meta-analysis

Oral Mucositis is a frequent and debilitating inflammatory complication in patients with head and neck malignancies and may lead to unplanned treatment interruptions due to intense pain and dysphagia. This systematic review with meta-analysis was performed to determine the effectiveness of low-level laser therapy in preventing oral mucositis in this context. The following databases were searched through September 2018, with last search performed on May 2019, for clinical trials: MEDLINE via PubMed, Cochrane Central, Scopus, Lilacs, ISI Web of Science and SIGLE via Open Grey. From 14,525 records, 4 studies were included in the review and 3 studies were included in meta-analysis. Data from 500 patients (mean age of 53.595 and 54.14 for intervention and control groups, respectively) were analysed. Meta-analysis showed that laser therapy prevents oral mucositis incidence in 28% and 23% of cases during the third and fourth follow-up week, respectively, in comparison to a placebo-treated control group. There was no statistically significant difference the prevention of pain; dysphagia and quality of life were not analysed due to missing. Laser therapy was effective in preventing oral mucositis from the 15th to the 45th days of chemoradiotherapy. However, new primary studies with low risk of bias are needed so a higher scientific evidence can be obtained.

The Effect of Fluence on Macrophage Kinetics, Oxidative Stress, and Wound Closure Using Real-Time In Vivo Imaging

Objective: The aim of our study was to quantify the effect of doses delivered by a He:Ne laser on individual macrophage kinetics, tissue oxidative stress, and wound closure using real-time in vivo imaging. Background: Photobiomodulation has been reported to reduce tissue inflammation and accelerate wound closure; however, precise parameters of laser settings to optimize macrophage behavior have not been established. We hypothesized that quantitative and real-time in vivo imaging could identify optimal fluence for macrophage migration, reduction of reactive oxygen species, and acceleration of wound closure. Methods: Larval zebrafish Tg(mpeg-dendra2) were loaded with dihydroethidium for oxidative stress detection. Fish were caudal fin injured, treated with 635 nm continuous 5 mW He:Ne laser irradiation at 3, 9, or 18 J/cm² and time-lapsed imaged within the first 120 min postinjury. Images taken 1 and 24-h postinjury were compared for percentage wound closure. Results: A fluence of 3 J/cm² demonstrated significant increases in macrophage migration speed, fewer stops along the way, and greatest directed migration toward the wound. These findings were associated with a significant reduction in wound content reactive oxygen species when compared with control wounded fins. Both 3 and 9 J/cm² significantly accelerated wound closure when compared with nonirradiated control fish. Conclusions: Wound macrophage activity could be manipulated by applied fluence, leading to reduced levels of wound reactive oxygen species and accelerated wound closure. The zebrafish model provides a means to quantitatively compare wound macrophage behavior in response to a variety of laser treatment parameters in real time.

Immediate dental implants placed into infected sites present a higher risk of failure than immediate dental implants placed into non-infected sites: Systematic review and meta-analysis

Background

Alveolar infection is known as a risk factor for implant failure. Current meta-analysis on the theme could not prove statistically that immediate dental implants placed into infected sites have a higher risk of failure than immediate dental implants placed into non-infected sites. The purpose of this meta-analysis was to determine the effectiveness of immediate dental implants placed into infected versus non-infected sites.

Material and Methods

Seven databases were sought by two reviewers. Randomized or non-randomized clinical trials that compared the placement of dental implants into infected versus non-infected sites were eligible for the study. Exclusion criteria were: papers in which the survival rate was not the primary outcome; papers without a control group; studies with less than one year of follow-up; studies whose patients did not receive antibiotic therapy; studies with medically compromised patients; duplicated papers. Risk of bias assessment was performed with the Cochrane Collaboration tool.

Results

Of the 3.253 initial hits, 8 studies were included in both qualitative and quantitative synthesis (kappa=0.90; very good agreement). Forest plot for implant failure showed that immediate implants placed into infected sites presented a statistically significant risk of failure that is almost 3 times higher than when placed into non-infected sites (risk ratio= 2.99; 95% confidence interval: 1.04, 8.56; p= 0.04; 935 implants; i2= 0%). Peri-implant outcomes showed no statistical difference.

Conclusions

Immediate dental implants placed into infected sites presented a statistically significant higher risk of failure than immediate dental implants placed into non-infected sites. Peri-implant outcomes were not statistically affected in this intervention.

Key words:Dental implants, infection, tooth socket, systematic review, immediate placement.

Photobiomodulation Therapy in Veterinary Medicine: A Review

Laser therapy, or photobiomodulation, has rapidly grown in popularity in human and veterinary medicine. With a number of proposed indications and broad, sometimes anecdotal, use in practice, research interest has expanded aimed at providing scientific support. Recent studies have shown that laser therapy alters the inflammatory and immune response as well as promotes healing for a variety of tissue types. This review will cover the history of the modality, basic principles, proposed mechanisms of action, evidence-based clinical indications, and will guide the practitioner through its application in practice.

Laser phototherapy induces angiogenesis in the periodontal tissue after delayed tooth replantation in rats

Background

Laser phototherapy (LPT) has been suggested as a new therapeutic tool to improve the repair of replanted teeth. However, its effects and mechanism of action are not yet completely understood.

Objectives

This study evaluated histologically the effect of laser phototherapy (LPT) λ808 and λ660 nm on angiogenesis in the periodontal tissue of replanted teeth in rats.

Material and Methods

Twenty maxillary right incisors were extracted from twenty Wistar rats and randomly assigned to four groups (n = 5): PN - teeth were stored in paper napkin for 45 min; WM - teeth were immersed in 20 ml of UHT whole cow milk for 45 min; PNL and WML - teeth received the same treatment described for PN and WM, respectively, plus LPT at λ808 and λ660 nm. All root canals were prepared and filled with calcium hydroxide paste. The animals were euthanized 15 days after tooth replantation and angiogenesis was scored by blood vessel counting in the area of periodontal ligament and alveolar bone, using the ImageJ software. Data were analyzed statistically by ANOVA and Tukey's test (α = 5%).

Results

LPT at λ808 and λ660 nm caused significant increased angiogenesis on irradiated groups (PNL and WML) when compared to the non-irradiated groups (PN and WM) (p<0.05). There was no statistically significant difference between PN and WM as well as between PNL and WML (p>0.05).

Conclusions

LPT is capable of stimulating angiogenesis in vivo in the periodontal tissue of replanted teeth. Key words:Angiogenesis, lasers, tooth avulsion, tooth replantation, wound healing.

Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm²) using different transmission modes (continuous or pulsed). The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm²; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing.

Mechanisms and applications of the anti-inflammatory effects of photobiomodulation

Photobiomodulation (PBM) also known as low-level level laser therapy is the use of red and near-infrared light to stimulate healing, relieve pain, and reduce inflammation. The primary chromophores have been identified as cytochrome c oxidase in mitochondria, and calcium ion channels (possibly mediated by light absorption by opsins). Secondary effects of photon absorption include increases in ATP, a brief burst of reactive oxygen species, an increase in nitric oxide, and modulation of calcium levels. Tertiary effects include activation of a wide range of transcription factors leading to improved cell survival, increased proliferation and migration, and new protein synthesis. There is a pronounced biphasic dose response whereby low levels of light have stimulating effects, while high levels of light have inhibitory effects. It has been found that PBM can produce ROS in normal cells, but when used in oxidatively stressed cells or in animal models of disease, ROS levels are lowered. PBM is able to up-regulate anti-oxidant defenses and reduce oxidative stress. It was shown that PBM can activate NF-kB in normal quiescent cells, however in activated inflammatory cells, inflammatory markers were decreased. One of the most reproducible effects of PBM is an overall reduction in inflammation, which is particularly important for disorders of the joints, traumatic injuries, lung disorders, and in the brain. PBM has been shown to reduce markers of M1 phenotype in activated macrophages. Many reports have shown reductions in reactive nitrogen species and prostaglandins in various animal models. PBM can reduce inflammation in the brain, abdominal fat, wounds, lungs, spinal cord.