Search Results (1,290)

Objective: The aim of this systematic review was to evaluate the effectiveness and safety of various laser wavelengths for debonding orthodontic metal brackets compared to traditional plier-based methods. The primary outcomes assessed were enamel damage, pulp temperature changes, adhesive remnant index (ARI), and shear bond strength (SBS). Materials and Methods: In September 2024, an electronic search was performed across the PubMed, Web of Science (WoS), and Scopus databases, adhering to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the PICO framework. The initial search yielded 453 records. After eliminating 256 duplicates, 197 unique records were left for screening, which ultimately led to the qualification of 8 articles that met the inclusion criteria for both qualitative and quantitative analyses. The risk of bias in the articles was assessed by two independent reviewers. Results: The included studies demonstrated that laser-assisted debonding generally resulted in less adhesive residue on the enamel surface compared to conventional methods, as evidenced by the reductions in ARI scores reported in two studies. Temperature increases during laser use varied depending on the laser type and power settings. The Nd:YAG (neodymium-yttrium, aluminum, garnet) laser was found to cause significant temperature rises, posing a potential risk to pulp tissue, while the Er:YAG (erbium—yttrium, aluminum, garnet) and Er,Cr:YSGG (erbium, chromium—yttrium, scandium, gallium, garnet) lasers produced only negligible increases in pulp temperature. SBS comparisons revealed no significant differences between the laser-assisted and traditional debonding methods. Additionally, diode lasers demonstrated the potential to minimize enamel damage, particularly when operated at lower power settings. Four publications were assessed as high quality (low risk of bias), and another four as moderate quality (average risk of bias). Conclusions: In conclusion, laser-assisted orthodontic metal bracket debonding, when conducted with appropriately calibrated parameters, is a safe method for preserving tooth tissue. However, its advantages appear to be minimal compared to conventional plier-based methods, highlighting the need for further research to justify its broader clinical application. Full article

Laser cladding technology is an effective method for producing wear-resistant coatings on damaged substrates, improving both wear and corrosion resistance, which extends the service life of components. However, the fabrication of hard and brittle materials is highly susceptible to the problem of cracking. Using gradient transition layers is an effective strategy to mitigate the challenge of achieving crack-free laser-melted wear-resistant coatings. This study presents the cracking issue of laser cladding Ni60B (NiCrBSi) coatings on 38CrMoAl (18CrNiMo7-6) steel by designing a gradient transition layer infused with varying amounts of Ni powder. We examine how different levels of Ni doping in the transition layer influence the fabrication of the Ni60B coating. The results indicate that the cracking mechanism of Ni60B is primarily due to the brittleness and hardness of the fusion cladding layer, which can result in cold cracks under residual tensile stress. Increasing the nickel content in the transition layer reduces the difference in thermal expansion coefficients between the cladding layer and the substrate. Additionally, the nickel in the transition layer permeates the cladding layer due to the laser remelting effect. The physical phase within the cladding layer transitions from the initial CrB, M₇C₃, and γ-Ni solid solution to γ-Ni solid solution and Ni-B-Si eutectic, with a small amount of boride and carbide hard phases. As the nickel doping in the transition layer increases, the proportion of the toughness phase dominated by Ni elements significantly rises, leading to a decrease in the hardness of the fused cladding layer. However, the average hardness of the fusion cladding layer in crack-free samples was measured at 397.5 ± 5.7 HV_0.2, which is 91% higher than that of the substrate. Full article

Background and Objectives: Distal tibia fractures are high-energy injuries characterized by a mismatch between standard plate designs and the patient’s specific anatomical bone structure, which can lead to severe soft tissue damage. Recent advancements have focused on the development of customized metal plates using three-dimensional (3D) printing technology. However, 3D-printed metal plates using titanium alloys have not incorporated a locking system due to the brittleness of these alloys. Therefore, this study aimed to determine whether a locking mechanism can be effectively implemented using 3D-printed pure titanium and further evaluate the clinical outcomes of such implants in patients with distal tibia fractures. Materials and Methods: Between March 2021 and June 2022, nine patients who underwent open reduction and internal fixation for distal tibia fractures using 3D-printed pure titanium plates were enrolled. Pure titanium powder (Ti Gr.2, Type A, 3D Systems, USA) was spread to a thickness of 30 μm and partially sintered using a 500 W laser to produce the 3D-printed metal plates. The locking screws were fabricated using a milling process. Open reduction and internal fixation were performed on the nine patients using 10 customized plates. The clinical efficacy was analyzed using the union rate, and complications, such as infection and skin irritation, were evaluated to ensure a comprehensive outcome assessment. Results: Surgical treatment was successfully performed on nine patients, with nine of ten plates remaining stable and undamaged. However, one patient with neurofibromatosis experienced a fractured metal plate, which necessitated revision surgery using a metal rod. No screw loosening or surgical wound complications occurred. Conclusions: This study showed that 3D-printed pure titanium plates with integrated locking screw systems provide a viable and effective solution for managing distal tibia fractures. Three-dimensional printing and pure titanium show promise for orthopedic advancements. Full article

Fiber Bragg gratings (FBGs) inscribed by UV light and different femtosecond laser techniques (phase mask, point-by-point, and plane-by-plane) were exposed—in several irradiation cycles—to accumulated high doses of gamma rays (up to 124 MGy) and neutron fluence (8.7 × 10¹⁸/cm²) in a research-grade nuclear reactor. The FBG peak wavelengths were measured continuously in order to monitor radiation-induced shifts. Gratings inscribed on pure silica core fibers using near-IR femtosecond pulses through a phase mask showed the smallest shifts (<30 pm), indicating that these FBGs are suitable for temperature measurement even under extreme ionizing radiation. In contrast, the pointwise inscribed femtosecond gratings and a UV-inscribed grating showed maximal shifts of around 100 pm and 400 pm, respectively. Radiation-induced red shifts are believed to arise from gamma radiation damage, which may partially recover after irradiation is stopped. At the highest neutron exposures, grating peak blue shifts started to appear, apparently due to fiber compaction. Full article

The tribological behavior of silicon nitride (Si₃N₄) ceramic with textured patterns under water lubrication was investigated in this paper. Different textured patterns were fabricated using laser surface texturing (LST). Surface wettability was characterized by contact angle. The original surface and textured Si₃N₄ ceramic with triangular patterns presented as hydrophobic. However, the textured Si₃N₄ ceramic with hexagonal patterns presented as hydrophilic. Surface wettability and textured patterns were important factors affecting the friction performance of the Si₃N₄ ceramic. Our results indicated that symmetrical textured patterns were more beneficial for decreasing the coefficient of friction (COF) at lower reciprocating frequencies. In contrast, better surface wettability played a more important role in reducing the COF at higher reciprocating frequencies. The most severe damage observed on the untextured Si₃N₄ ceramic led to a higher wear rate. The symmetrical structure of hexagonal patterns was more conducive to decreasing the wear rate than triangular patterns. However, the Si₃N₄ ceramic with triangular patterns was more suitable for use at high-speed frictions due to better lubrication. The textured patterns had the function of storing lubricants and capturing and cutting debris. Thus, friction performance was improved by introducing textured patterns onto the surface of the Si₃N₄ ceramic. The friction and wear mechanisms are also discussed in this study. Full article

The Ti-6Al-4V alloy is widely utilized in the aerospace industry for applications such as turbine blades, where it is valued for its mechanical strength at high temperatures, low specific gravity, and resistance to corrosion and oxidation. This alloy provides crucial protection against oxidation and thermal damage. A thermal barrier coating (TBC) typically consists of a metallic substrate, a bond coating (BC), a thermally grown oxide (TGO), and a topcoat ceramic (TC). This study aimed to investigate laser parameters for forming a TBC with a NiCrAlY bond coating and a zirconia ceramic topcoat, which contains 16.0% equimolar yttria and niobia. The coatings were initially deposited in powder form and then irradiated using a CO₂ laser. The parameters of laser power and beam scanning speed were evaluated using scanning electron microscopy and X-ray diffraction. The results indicated that the optimal laser scanning speed and power for achieving the best metallurgical bonding between the substrate/BC and the BC-TGO/TC layers were 70 mm/s at 100 W and 550 mm/s at 70 W, respectively. Laser-based layer formation has proven to be a promising technique for the application of TBC. Full article

In the realm of advanced optical fiber sensing (OFS) technologies, Fiber Bragg Grating (FBG) has garnered widespread application in the monitoring of temperature, strain, and external refractive indices, particularly within high-radiation environments such as high-energy physics laboratories, nuclear facilities, and space satellites. Notably, FBGs inscribed using femtosecond lasers are favored for their superior radiation resistance. Among various inscription techniques, the point-by-point (PbP) and line-by-line (LbL) methods are predominant; however, their comparative impacts on radiation durability have not been adequately explored. In this research, FBGs were inscribed on a single-mode fiber using both the PbP and LbL methods, and subsequently subjected to a total irradiation dose of 5.04 kGy (radiation flux of 2 rad/s) over 70 h in a ⁶⁰Co-γ radiation environment. By evaluating the changes in temperature- and strain-sensing performance of the FBG pre-irradiation and post-irradiation, this study identifies a more favorable technique for writing anti-irradiation FBG sensors. Moreover, an analysis into the radiation damage mechanisms in optical fibers, alongside the principles of femtosecond laser inscription, provides insights into the enhanced radiation resistance observed in femtosecond laser-written FBGs. This study thus furnishes significant guidance for the development of highly radiation-resistant FBG sensors, serving as a critical reference in the field of high-performance optical fiber sensing technologies. Full article

The laser-induced damage threshold (LIDT) is a key measure of an optical component’s resistance to laser damage, making its accurate determination crucial. Following the ISO 21254 standards, we studied the measurement strategy and uncertainty fitting method for laser damage, establishing a calculation model for uncertainty. Research indicates that precise LIDT measurement can be achieved by using a small energy level difference and conducting multiple measurements. The LIDT values for the cylindrical grating are 15.34 ± 0.00052 J/cm² (95% confidence) and 15.34 ± 0.00078 J/cm² (99% confidence), demonstrating low uncertainty and reliable results. This strategy effectively measures the LIDT and uncertainty of various grating surface shapes, offering reliable data for assessing their anti-laser-damage performance. Full article

The European Society for Laser Dermatology (ELSD) has established recommendations for safe and effective photo epilation; however, short-term common adverse effects occur as a result of laser treatment, such as edema and perifollicular erythema. Post-inflammatory hyperpigmentation also appears in certain skin types. Very few clinical studies have been conducted on the topical application of cosmetic skin care products aimed at decreasing the adverse effects on the skin epidermis following laser-assisted epilation procedures. Stem cells are found in plant and animal organisms and are responsible for the growth and restoration of damaged tissues. Plant stem cells divide throughout the life of the plant, creating new plant parts. Our aim was to develop a new cosmetic cream to decrease the intensity of some of the side effects of laser epilation and thus reduce the administration of topical medication. We developed a formulation with the active substance Olea europaea (Olive) Callus Culture Lysate (OLEA VITAE™ 02), which is derived from plant stem cells of the Mediterranean wild variety of Olea europaea, for application following laser epilation with an Nd:YAG 1064 nm laser. The new skin care cream was tested for its physicochemical and microbiological stability, according to the European Pharmacopoeia. The impacts of this substance on the potential side effects of Nd:YAG 1064 nm application, i.e., trans-epidermal water loss, keratin hydration, melanin, erythema, and skin elasticity, in comparison with the appropriate placebo, were investigated using biophysical measurements and a self-assessment questionnaire. Skin biopsies were also performed to evaluate the influence of the procedure and the application of the products on the epidermis and papillary dermis thickness. According to our findings, the incorporation of the plant stem cell extract of Olea europaea into our cream resulted in a stable cream with an appealing texture. Furthermore, the activity of erythema and hyperpigmentation was decreased when the cream was applied after Nd:YAG 1064 nm laser epilation. Full article

Paper-based artworks are prone to natural aging processes driven by chemical and biological processes. Numerous treatments have been developed to mitigate deterioration and prevent irreversible damage. In this study, we investigated the use of poly(acrylic acid)/TiO₂ composite hydrogels, combining their cleaning and protective functions in a minimally invasive treatment. Hydrogels allow for controlled water flow and photocatalytic TiO₂ nanoparticles enhance the hydrogel’s efficacy by enabling the removal of oxidation products and inactivating biological contaminants. Furthermore, this innovative material can act as a protective coating against UV-induced aging, preserving both color and stability of the paper. Raman spectroscopy and confocal laser scanning microscopy imaging techniques were employed to evaluate the treatments, allowing for us to differentiate between hydrolytic and oxidative aging processes. Our findings demonstrate that papers coated with poly(acrylic acid)/TiO₂ composite hydrogels exhibit significant reductions in oxidative markers, an enhanced color stability, and an overall improved resistance to degradation compared to uncoated samples. Full article

This study employed different spot pattern lasers to clean the oxide film on the surface of a TC4 titanium alloy. The variation in temperature field and ablation depth during the laser cleaning process was simulated by establishing a finite element model. The effects of various laser processing parameters on the micromorphology, elemental composition, and surface roughness of the TC4 titanium alloy were analyzed. The results show that as the laser energy density increases, both the temperature field and ablation depth increase as well. Under optimal laser processing parameters, the laser energy density is 5.27 J/cm², with a repetition frequency of 300 kHz and a scanning speed of 6000 mm/s. A comparison of the cleaning effects of Gaussian pulse lasers and Flat-top pulse lasers reveals that the Gaussian pulse laser causes less damage to the TC4 titanium alloy, resulting in lower oxygen content and roughness values after cleaning compared to Flat-top pulse laser cleaning. Full article

Minimally invasive endovascular stent electrodes are an emerging technology in neural engineering, designed to minimize the damage to neural tissue. However, conventional stent electrodes often rely on resistive welding and are relatively bulky, restricting their use primarily to large animals or thick blood vessels. In this study, the feasibility is explored of fabricating a laser welding stent electrode as small as 300 μm. A high-precision laser welding technique was developed to join micro-wire electrodes without compromising structural integrity or performance. To ensure consistent results, a novel micro-wire welding with platinum pad method was introduced during the welding process. The fabricated electrodes were integrated with stent structures and subjected to detailed electrochemical performance testing to evaluate their potential as neural interface components. The laser-welded endovascular stent electrodes exhibited excellent electrochemical properties, including low impedance and stable charge transfer capabilities. At the same time, in this study, a simulation is conducted of the electrode distribution and arrangement on the stent structure, optimizing the utilization of the available surface area for enhanced functionality. These results demonstrate the potential of the fabricated electrodes for high-performance neural interfacing in endovascular applications. The approach provided a promising solution for advancing endovascular neural engineering technologies, particularly in applications requiring compact electrode designs. Full article

Quantum dots (QDs) have emerged as promising tools in advancing multiphoton microscopy (MPM) for deep brain imaging, addressing long-standing challenges in resolution, penetration depth, and light–tissue interactions. MPM, which relies on nonlinear photon absorption, enables fluorescence imaging within defined volumes, effectively reducing background noise and photobleaching. However, achieving greater depths remains limited by light scattering and absorption, compounded by the need for balanced laser power to avoid tissue damage. QDs, nanoscale semiconductor particles with unique optical properties, offer substantial advantages over traditional fluorophores, including high quantum yields, large absorption cross-sections, superior photostability, and tunable emission spectra. These properties enhance signal to background ratio at increased depths and reduce scattering effects, making QDs ideal for imaging subcortical regions like the hippocampus without extensive microscope modifications. Studies have demonstrated the capability of QDs to achieve imaging depths up to 2100 μm, far exceeding that of conventional fluorophores. Beyond structural imaging, QDs facilitate functional imaging applications, such as high-resolution tracking of hemodynamic responses and neural activity, supporting investigations of neuronal dynamics and blood flow in vivo. Their stability enables long-term, targeted drug delivery and photodynamic therapy, presenting potential therapeutic applications in treating brain tumors, Alzheimer’s disease, and traumatic brain injury. This review highlights the impact of QDs on MPM, their effectiveness in overcoming light attenuation in deep tissue, and their expanding role in diagnosing and treating neurological disorders, positioning them as transformative agents for both brain imaging and intervention. Full article

Background: Endometriosis is characterized by the presence of endometrial tissue outside the uterus. Beyond medical treatment, surgical intervention is also a viable consideration. However, current guidelines do not clearly indicate whether laparoscopic cystectomy, ablative methods (CO₂ laser vaporization, plasma energy), or sclerotherapy is the preferred option. Methods: We conducted searches in two databases (PubMed and Europe PMC) to retrieve articles containing the keywords ‘surgical intervention for Endometrioma, ovarian reserve, pregnancy rates, fertility’, published between 1 January 2000 and 31 December 2023. We included articles presenting information on surgical intervention for endometrioma and its correlation with infertility parameters. Articles describing conservative treatment were excluded. Data were extracted by two authors using predefined criteria. Results: The initial database search produced 1376 articles, which were narrowed down to 41 relevant articles meeting the eligibility criteria. Conclusions: Laparoscopic cystectomy appears to impact postoperative anti-mullerian hormone levels, showing a stronger correlation with larger cysts and individual factors. CO₂ laser vaporization demonstrates favorable results compared to traditional cystectomy. Combining GnRH agonist treatment with assisted reproduction treatment after cystectomy could be considered an alternative method. Plasma energy causes less damage to ovarian function, with pregnancy outcomes comparable to cystectomy. Sclerotherapy shows promising results for ovarian reserve preservation, recurrence rates, and safety. Further studies comparing these techniques are necessary to provide guidance to clinicians. Full article

Conserving micromosaics from the Gilbert collection at the Victoria and Albert Museum is a challenge due to their complex structure and fragility. Their highly polished decorative surface prevents access to the substrate, yet deterioration can affect both, and manifests as cracking, failure and losses of the substrate and grouting, and as yellowing and accumulation of dirt on the uppermost organic coating. In order to minimise any possible damage to the substrate while cleaning the surface with solvents, laser cleaning using an Er:YAG laser was investigated on various micromosaic objects. Tests were first conducted on a non-displayable bonbonnière, and digital microscopy and scanning electron microscopy were performed to investigate the effects of the laser on the different materials; the results were then compared to solvent-cleaning only. The combination leading to the most effective cleaning results was found to be laser irradiation at fluences up to 0.71 J·cm⁻² on the surface, followed by gentle swabbing with solvent. The surface was successfully cleaned with no changes induced on the materials, and a much lower amount of solvent was used. Following these successful preliminary tests, cleaning was undertaken on other pieces of the collection, and the outcome is presented in this study. The results show a great variability in terms of response of the materials to solvents, emphasising the need to consider each item on a case-by-case basis. Full article