Search Results (82)

This study presents a comparative morphological and elemental characterization of organomineral coatings composed of polydopamine (PDA) and nanocrystalline carbonate-substituted hydroxyapatite (nano-cHAp), formed on model Si(111) substrates and human enamel specimens. Three technologically distinct routes were investigated: sequential PDA/HAp/PDA deposition without an external field (NF), one-step PDA/HAp co-deposition without applied voltage (F0, U = 0 V), and one-step PDA/HAp co-deposition under applied voltage (F, U = 50 V). X-ray diffraction was employed to verify the apatite-like structure of the initial nanocrystalline HAp and to identify drying-related contributions from the TRIS-containing medium; however, it was not used as direct evidence of the HAp phase or texture in the final coatings. SEM segmentation of selected enamel areas showed that the area fraction assigned to the morphologically continuous surface-layer class was approximately 85% for NF, 73% for F0, and 95.5% for F. Representative AFM analysis on Si(111) revealed a rough, topographically heterogeneous F0 layer (S_q ≈ 68 nm, height range ≈ 440–490 nm), a pronounced island-like NF morphology (S_q ≈ 45 nm), and a lower-amplitude F morphology (S_q ≈ 4 nm). For the F coating, scratch-edge profiling indicated an apparent step height of approximately 88 nm, while a preliminary ultrasonic retention challenge in water for 5 min at a 30 mm sample-to-probe distance preserved this apparent step height and reduced S_q from approximately 12 to 5 nm. Point-EDX-derived visualization on Ca/P-free Si(111) supported the presence of Ca/P-containing domains and indicated different spatial organization of the mineral component across the NF–F0–F sequence. FTIR and micro-Raman spectroscopy were performed for the two terminal routes, NF and F, and were interpreted as qualitative evidence of PDA- and HAp-related spectral features rather than as a comprehensive quantitative comparison of all deposition modes. Overall, the data support a transition from island-like or domain-heterogeneous coatings toward a more laterally continuous, lower-amplitude surface layer in the one-step field-assisted route. The results remain morphology-oriented and do not demonstrate clinical remineralization, HAp texture, long-term oral stability, or quantitative adhesion strength. Full article

Background: Nanotechnology-based surface coatings show promise in enhancing the antibacterial activity and mechanical performance of orthodontic materials. Although numerous in vitro studies suggest some benefits, the clinical relevance of these effects in vivo remains uncertain. Objectives: The aim of this systematic review was to assess whether nanocoated orthodontic materials improve clinical and clinically derived laboratory outcomes in in vivo human studies, including microbial adhesion, enamel mineralization, surface characteristics and other treatment-related parameters. Materials and Methods: An electronic literature search was conducted up to 31 July 2025, yielding 15,330 records after duplicate removal. Only in vivo studies using nanocoated materials in patients undergoing orthodontic treatment were included. Study selection, data extraction, risk-of-bias assessment and certainty-of-evidence assessment were performed independently by two reviewers. Risk of bias was assessed using RoB 2 and ROBINS-I, and certainty of evidence was evaluated using GRADE. Results: A total of 13 studies were included in the qualitative synthesis. The comparative appliances were coated and uncoated brackets, tubes, archwires, miniscrews and modules. Most studies primarily assessed microbial outcomes. Overall, nanocoated orthodontic appliances showed promising antimicrobial properties and lower bacterial adhesion in several studies. Other studies assessed enamel demineralization, surface characteristics, bond failure, orthodontic miniscrew success rate and rate of canine retraction. Conclusions: Although the included studies indicate promising results, confidence is limited by heterogeneity in nanoparticle types, coating protocols and outcome measures. Safety outcomes, including coating degradation and long-term local or systemic effects, were not adequately assessed. Further well-designed randomized trials with standardized and clinically meaningful outcomes are needed before routine clinical implementation can be supported. Full article

Fixed orthodontic appliances promote biofilm-mediated enamel demineralization and release metallic ions, motivating surface strategies that are intrinsic to the device rather than dependent on patient compliance. Chitosan, a biodegradable polycationic biopolymer, has been proposed as a multifunctional coating. This narrative review critically appraises the evidence for chitosan-based coatings on orthodontic appliances across three pillars—antimicrobial performance, ion-release/corrosion mitigation, and clinical translation—with explicit calibration of evidentiary strength. The evidence base is heterogeneous and of markedly uneven quality across the three pillars, and the conclusions below are weighted accordingly. Consistent with its narrative design, the literature was surveyed for critical synthesis rather than exhaustively, without formal eligibility screening, risk-of-bias appraisal, or quantitative pooling. Antimicrobial efficacy is the best-supported pillar, consistent in vitro and now extended by two short in vivo randomized trials, although all endpoints are microbiological surrogates rather than white spot lesion outcomes. Ion-release mitigation remains a plausible but insufficiently demonstrated effect: it is supported only indirectly, through electrochemical corrosion proxies on predominantly implant substrates, and no study quantifies ion-release reduction from a coated appliance. Coating durability under combined enzymatic and mechanical load—and its effect on friction—remains largely uncharacterized. Chitosan coatings are promising but translationally immature; durability, not antimicrobial potency, is the rate-limiting barrier. Defined clinical-endpoint and appliance-level ion-release studies are required. Full article

This in vitro study compared the bond strength performance and adhesive remnant characteristics of two metallic orthodontic pre-coated bracket systems: APC™ Plus and APC™ Flash Free. Forty extracted human premolars were randomly allocated to two groups (n = 20). Following enamel etching with 37% phosphoric acid, brackets were bonded according to the manufacturers’ recommendations. Bond strength testing was performed using a custom-made apparatus in which failure was induced through a progressively increasing load. Because the experimental setup generated a combined loading configuration involving shear, tensile, and bending components, the measured values should be interpreted as comparative bond strength measurements rather than absolute shear bond strength values. Adhesive Remnant Index (ARI) scores were recorded after debonding to evaluate failure patterns. Median bond strength values were 17.75 MPa (IQR: 13.53–21.98) for APC™ Plus and 14.28 MPa (IQR: 9.81–18.74) for APC™ Flash Free. No statistically significant difference was found between groups (Mann–Whitney U test, p = 0.102). In contrast, ARI score distributions differed significantly (Fisher’s exact test, p = 0.001). APC™ Plus brackets predominantly exhibited ARI scores of 2–3, whereas APC™ Flash Free brackets mainly demonstrated ARI scores of 1–2, indicating less adhesive remaining on the enamel surface after debonding. Three enamel fractures were observed in the APC™ Plus group, while none occurred in the APC™ Flash Free group; however, no statistically significant association between bracket type and enamel fracture was identified. Within the limitations of this in vitro study, both bracket systems demonstrated comparable bond strength performance under the experimental conditions investigated. APC™ Flash Free brackets were associated with reduced adhesive remnants on enamel, which may facilitate post-debonding cleanup. Further studies using standardized testing methods and prospective clinical investigations are required to confirm these findings and determine their clinical relevance. Full article

Insulation failure in aviation generator windings is one of the most common faults. Modern aircraft winding materials often employ polyimide enameled wire, making research on its reliability and health monitoring particularly important. Based on the relationship between temperature and aging rate described by the Arrhenius law, this study designed accelerated thermal aging experiments, testing twisted-pair, coil, and winding samples made of copper-core polyimide enameled wire. The variation in multiple parameters was visualized using B-spline fitting, ultimately identifying parallel equivalent capacitance as the most suitable parameter for monitoring generator winding insulation. It was also indicated that aging of the winding insulation coating has almost no effect on the performance of the electrical system. Finally, experimental data were processed using Bayesian nonlinear regression, where prior data were updated with new data to obtain posterior aging curves. When the IC ($C_p$) value reaches 1.2009 and 1.4089 times its initial value, the sample is considered to have reached 50% and 100% of its lifespan, respectively. This provides a reference approach and quantitative indicators for predicting the lifespan of polyimide enameled wire windings. Full article

The present work aimed at resolving the mystery accompanying the famous Ko-Kutani Honzenji temple shallow bowl by investigating the main elements associated with the coating composition in the surface decoration. This unique vessel belongs to Honzenji temple, located in the Maeda Domain (today’s Ishikawa Prefecture) and is on display at the Ishikawa Prefecture Kutaniyaki Art Museum in Kaga. The Honzenji temple bowl bears a cryptic figure painted in red enamel on the underside and story has it that the Maeda Lord himself may have painted it in the mid-17th century, thus making the bowl a very relevant piece of the history of the Maeda clan, Ishikawa Prefecture (Maeda fiefdom in the Edo period), and Japanese porcelain as a whole. Yet the identification of the actual firing date of the bowl has proven a daunting task for curators worldwide. On the basis of the previously published studies on the world’s most extensive collection of Ko-Kutani Masterpieces belonging to the Ishikawa Prefectural Museum of Art, and shards excavated at Kaga kiln sites, including the celebrated Hakuji bowl (Ishikawa Archaeological Foundation), both conducted by Energy-Dispersive X-Ray Fluorescence spectroscopy (pED-XRF), and in consideration of the absolute prohibition to sample or even touch the Honzenji bowl, pED-XRF was once again selected as the most suitable technique for the analysis of all the enamels and glazing materials. Analytical evidence, for the first time ever, has proven crucial to resolving the issue by enabling the precise dating of the bowl and unveiling the true story behind its technical features and the cryptic underside decoration. Full article

The windings of aerospace motors are fabricated using enameled wires; with polyimide (PI) serving as the primary material for their insulating enamel coatings, thermal aging is the predominant factor contributing to insulation failure in enameled wires. The prolonged natural aging process of enameled wires, coupled with the complexity and sluggish variation rates of dielectric parameters used for aging monitoring, presents significant challenges in developing a universal method for assessing insulation performance. To address this challenge, our study determined accelerated aging conditions based on the Arrhenius law, fabricated twisted-pair specimens, and implemented a step-stress aging protocol, in order to monitor the insulation capacitance (IC) and dielectric dissipation factor (tan δ) of the sample. Finally, a two-parameter Weibull distribution plot was established to characterize the relationship between service life and failure probability. Initial-value normalization combined with B-spline interpolation was employed to construct IC–life correlation curves. A novel method for monitoring PI-enameled wire insulation life using IC variation rate was proposed and experimentally validated, providing a methodological framework for lifespan prediction of aerospace motor windings. Finally, a two-parameter Weibull distribution plot was established to characterize the relationship between service life and failure probability. Initial-value normalization combined with B-spline interpolation was employed to construct IC–life correlation curves. The rationality of the method using IC change rate to monitor the insulation lifetime of polyimide-enameled wire was verified, the lifetime assessment of aviation motor stator windings was achieved by monitoring corresponding dielectric parameters, and a reference standard for the maintenance and support of aviation equipment was provided. Full article

The development of hybrid organic coatings for corrosion protection remains a key research priority. This study focuses on synthesising Layered Double Hydroxide (ZnGa-LDHs) intercalated with environmentally friendly disodium sebacate (SB) corrosion inhibitor, forming ZnGa-SB. To overcome the challenge of limited dispersibility in organic coatings, ZnGa-SB was combined with Graphene Nanoribbons (GNR), produced through the oxidative unzipping of multi-walled carbon nanotubes (MWCNT). The resulting composite, ZnGa-SB/GNR, was synthesised using an in situ hydrothermal method and incorporated into polyurethane (PU) enamel. The synergy between high-barrier GNRs and active ZnGa-SB creates a “labyrinth effect” that effectively inhibits the diffusion of corrosive species. Microstructural analysis, including XRD, FT-IR, Raman, TGA, FE-SEM, and EDS, confirmed the nanofiller structure. The nanofillers were embedded into acrylic resin (AC) for short-term anticorrosive testing in a 0.1 M NaCl solution and then into PU for long-term evaluation in a 3.5 wt% NaCl solution, using electrochemical impedance spectroscopy (EIS). The PU/ZnGa-SB/GNR coating exhibited a high impedance modulus of 5.90 × 10⁷ Ω cm² at |Z|_0.01 Hz, even after 2688 hours of immersion, indicating enhanced corrosion resistance. This coating demonstrated superior performance in cross-cut and pencil hardness tests and sustained less damage in salt spray analysis compared to other coatings. The synergistic effect offers a promising approach for developing next-generation hybrid anti-corrosive coatings. Full article

The study aims to reconstruct the life history of an individual whose skeleton was recovered during the excavation of the late medieval Pauline monastery of the Blessed Virgin Mary on Moslavina Mountain, Croatia. The monastery was one of the most important ecclesiastical centres in continental Croatia during the 14th/15th centuries CE and was abandoned between 1520 and 1544 due to fear of imminent Ottoman attacks. The inscription and coat of arms on the tombstone of a tomb located in the chancel, next to the main altar, indicate that the skeleton belongs to Sofia Kaštelančić née di Prata (di Pordenone), a member of Croatian late medieval high-ranking nobility. We conducted a conventional bioarchaeological study, carbon and nitrogen stable isotopes analysis, paleoradiological imaging (CT/CBCT scanning), and three-dimensional facial reconstruction. The skeleton belongs to a middle-aged woman between 40 and 50 years old with an estimated stature of about 161 cm. Numerous pathological changes, such as ante mortem tooth loss, caries, abscess, linear enamel hypoplasia, dysodontiasis, and osteophytosis were observed, with the most notable pathology being the fracture of the right ankle, a fact also confirmed by CT scanning. Carbon and nitrogen isotopic values are consistent with a terrestrial diet based on C₃ plants with no marine input, and the consumption of large quantities of animal-based proteins. Three-dimensional facial reconstruction made it possible for the first time in over 500 years to obtain the approximate physical appearance of the individual. The presented results are consistent with the hypothesis that the skeleton probably belongs to Sofia Kaštelančić. Nevertheless, none of the observed osteological traits are individually or collectively diagnostic of Sofia, so, in the absence of individualising evidence, the identification remains hypothetical rather than demonstrative. Full article

This study develops a comprehensive decision-making approach to sustainable product selection for chemical industry supply chains under uncertainty. Five product categories -enamel, ceramics, pigments, non-stick coatings, and glass- were evaluated through fifteen criteria along environmental, economic, and social sustainability dimensions. The hybrid methodology combines Fuzzy SWARA, which weights criteria based on expert opinion, with Fuzzy ARAS, which ranks the alternatives accordingly. The study found that occupational health and safety, consumer safety and health, and water usage are the most important criteria, reflecting a human-centered approach to sustainability decision-making. Ceramics had the best performance score, followed by enamel and non-stick coating. Sensitivity analysis confirmed the robustness of these rankings across various weighting scenarios. The findings indicate that decision-makers in the chemical industry prioritize worker and consumer protection alongside environmental resource stewardship. This framework provides practitioners with a structured method for integrating sustainability considerations into supply chain product portfolio decisions, balancing environmental impact, economic performance, and social responsibility. Full article

Background/Objectives: The aim of this study was to evaluate the effects of sodium trimetaphosphate (TMP) and fluoride (F) on the surface free energy (SFE) of enamel coated with human salivary pellicle in vitro, both after treatment with the gels and after an erosive challenge. Methods: Bovine enamel discs (n = 10/group) were randomly allocated into seven treatment groups (gels): placebo (without any actives), low-fluoride gels (4500 ppm F—“4500F”) supplemented or not with microparticulate TMP (5%) or nanoparticulate (2.5% or 5%) TMP, 9000 ppm F (positive control), and 12,300 ppm F (acid gel, commercial control); a negative control group (i.e., untreated enamel) was included. Discs were exposed to human saliva (2 h), treated with the gels (1 min) and subjected to a 1-min acid challenge. Three probing liquids were used to assess enamel SFE. Data were submitted to two-way, repeated-measures ANOVA followed by Tukey’s test, and by Mann–Whitney’s test (p < 0.05). Results: SFE was significantly altered after exposure to saliva, changing from hydrophobic to slightly hydrophilic; gel treatment further increased enamel hydrophilicity (i.e., electron-donor properties), without significant differences among gels. After the erosive challenge, the enamel surface became significantly less hydrophilic for all groups; the highest values were observed for both gels containing nanoparticulate TMP. As for the overall SFE, the best performance was achieved by the gel containing 5% nanometric TMP. Conclusions: SFE of salivary-coated enamel was significantly influenced by the treatment gels, which promoted increases in hydrophilicity. Gels containing TMP, especially at nanoscale, promoted higher resistance to changes in hydrophilicity after an erosive challenge. Full article

Background: Substituted hydroxyapatites (HAps) are widely used in oral-care formulations for enamel repair; however, head-to-head comparisons among commercial grades remain limited. Objective: To compare four commercial HAps: A (Kal-HAp), B (FL-HAp), C (FL-HAp-SC), and D (microRepair^®, a biomimetic Zn–carbonate-substituted HAp) and to evaluate their ability to form an enamel-like coating in vitro. Methods: We characterized the powders by X-ray diffraction (crystalline phase, Landi crystallinity index), FTIR-ATR (phosphate/carbonate bands), SEM/EDS (morphology, surface Ca/P), and DLS (particles size, ζ-potential). In vitro, human enamel sections were treated with 5% slurries in artificial saliva; surface coverage was quantified by image analysis on SEM. Results: All commercial materials analyzed in this work were composed of HAp. Differences were observed between HApin terms of crystallinity-range [2 Theta 8.0–60.0°], carbonate substitution (ATR [carbonate group evaluated −870 cm⁻¹]), and particle size (DLS [in a range 0.1–10,000 nm], Z-mean [mV]). On enamel, all samples form a hydroxyapatite layer; coverage differed between groups ([A] 28.83 ± 7.35% vs. [B] 31.11 ± 3.12% vs. [C] 57.20 ± 33.12% vs. [D] 99.90 ± 0.12%), with the biomimetic Zn–carbonate-substituted HAp showing the highest coverage, and the post-treatment Ca/P ratio approached values similar to those of dental enamel. Conclusions: Complementary physic-chemical signatures (crystallinity, carbonate substitution, and morphology) relate to enamel-surface coverage in vitro, providing evidence base for selecting HAp grades for enamel-repair formulations, which is a practical implication for product design. Full article

Zirconia’s superior mechanical properties and biocompatibility have made it a cornerstone of modern prosthodontics, yet achieving durable biomimetic bonding to tooth structure remains a challenge. This scoping review synthesizes evidence on bonding strategies for zirconia-based fixed dental prostheses (FDPs), evaluating surface treatments, cementation protocols, and long-term performance. Following PRISMA-ScR guidelines, 18 studies from PubMed, Scopus, Web of Science, and Embase were thoroughly analyzed. Key findings indicate that tribochemical silica coating (e.g., Rocatec™) combined with 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primers (e.g., Panavia V5) is associated with the highest bond strengths (>40 MPa) and exceptional clinical survival rates (e.g., >95% at 15 years for resin-bonded FDPs). These combined mechanical–chemical strategies can be viewed as an attempt to create a biomimetic, hybrid interface akin to the natural enamel–dentin junction. Additively manufactured zirconia exhibits inferior bonding compared to milled counterparts, while ethyl cellulose coatings applied to the bonding surface effectively prevent contamination from saliva and moisture during intraoral try-in procedures. However, heterogeneous testing protocols and limited long-term clinical data highlight the need for standardized aging models and randomized trials. This review consolidates current evidence, offering clinically actionable recommendations through a biomimetic lens while identifying critical gaps for future research. Full article

Although approximately half of global lithium consumption is used in the rechargeable battery industry, lithium is also in demand for other specialized applications, such as high-temperature lubricants, ceramics, glass, and pharmaceuticals. The growing need for efficient lithium recovery and recycling underscores the importance of fast and accurate analytical tools for determining lithium concentrations in non-compliant and waste materials generated by industrial processes. In this paper, we present a machine learning-based procedure utilizing Laser-Induced Breakdown Spectroscopy (LIBS) to accurately quantify lithium concentrations in lithium-rich non-compliant materials derived from the industrial production of enamels used for coating metallic surfaces. This procedure addresses challenges such as strong self-absorption and matrix effects, which limit the effectiveness of conventional univariate calibration methods. By employing a multivariate approach, we developed a single model capable of quantifying lithium content across a wide concentration range. A comparison of the LIBS results with those obtained using conventional laboratory analysis (Inductively Coupled Plasma–Optical Emission Spectrometry, ICP-OES) confirms that LIBS can deliver the speed, precision, and reliability required for potential routine applications in the lithium recovery and recycling industry. Full article