Resection of Vestibular Schwannoma in a Highly Pneumatized Temporal Bone with Fat Graft-Assisted Cerebrospinal Fluid Leak Prevention: A Case-Based Technical Video Report.

Magnesium alloys are attractive biodegradable materials for biomedical implants; however, their clinical application is severely limited by rapid corrosion in physiological environments. In this study, Quench-produced Diamond (Q-Dia) films were deposited on Mg Ca alloy substrates at room temperature using the coaxial arc plasma deposition technique. Two surface pretreatments were employed prior to coating: (i) mechanical polishing and (ii) in-situ argon ion (Ar + ) etching, to clarify their influence on film formation and corrosion behavior. The surface morphology and bonding structure of the Q-Dia films were characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, revealing dense diamond-like grain growth with mixed sp 2 /sp 3 carbon bonding and a pronounced D-band feature. Corrosion performance was evaluated in simulated body fluid (SBF) at 37 °C using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), with bare Mg Ca alloy as a reference. The Q-Dia coating significantly enhanced corrosion resistance, increasing the polarization resistance from 255 Ω.cm 2 to 2756 Ω.cm 2 and reducing the corrosion rate by more than one order of magnitude. In addition, tribological tests conducted in SBF demonstrated a stable and low coefficient of friction (~0.15), indicating improved surface integrity under wet sliding conditions. A comparative analysis revealed that Ar + etching is more effective than mechanical polishing in improving the structure, morphology, and corrosion resistance of the Q-Dia coatings. These results demonstrate that Q-Dia films act as an effective protective barrier against corrosive degradation, highlighting their strong potential as surface coatings for biodegradable Mg-based implant applications. • Quenched-produced diamond coatings were deposited on Mg-Ca alloys by CAPD. • Surface pretreatment strongly influenced coating morphology, adhesion and barrier properties. • Corrosion resistance in simulated body fluid increased by over one order of magnitude. • A low and stable friction coefficient was achieved under wet sliding conditions. • Improved corrosion and tribological performance indicate effective surface protection.

Titanium and its alloys are extensively employed in biomedical implant applications owing to their excellent biocompatibility and corrosion resistance; however, their inherently poor tribological performance severely limits long-term reliability under load-bearing conditions. In this work, a highly adherent Quench-produced Diamond (Q-Dia) coating was deposited on commercially pure titanium using a hybrid coaxial arc plasma deposition (CAPD) technique combined with in situ Ar + plasma etching to enhance interfacial bonding. The resulting coating exhibits a dense nanocomposite architecture comprising nanodiamond crystallites embedded within an amorphous carbon matrix, which promotes strong coating–substrate adhesion, as evidenced by a high critical load (Lc₂) of 20.13 N determined from scratch testing. Dry sliding tribological tests against an Al₂O₃ counter-body revealed a substantial reduction in friction and wear compared with uncoated titanium. While bare titanium showed high and unstable coefficients of friction (0.497–0.567) accompanied by severe wear damage, the Q-Dia-coated surface achieved a low and stable steady-state friction coefficient of approximately 0.127 with no wear observed. Furthermore, electrochemical measurements conducted in simulated body fluid demonstrated a positively shifted corrosion potential for the Q-Dia coating (0.025 V ) relative to bare titanium (−0.324 V), indicating improved electrochemical stability. These findings demonstrate that Q-Dia coatings effectively mitigate the tribological limitations of titanium without compromising corrosion resistance, highlighting their strong potential for load-bearing biomedical implant applications operating under dry or boundary-lubricated conditions. • Hybrid CAPD enables room-temperature deposition of highly adherent (~3 μm) Q-Dia coatings on titanium. • Scratch testing reveals strong coating–substrate adhesion, with a high critical load of Lc₂ = 20.13 N. • Q-Dia coatings markedly enhance the tribological performance of pure titanium under dry sliding against Al₂O₃. • Extremely low steady-state friction coefficients down to 0.127 are achieved. • Superior wear resistance arises from a stable, carbon-rich tribo-layer formed via localized sp 3 -to-sp 2 rehybridization.

Abstract This study explores the structural, chemical, and tribological behavior of boron-doped diamond coatings deposited on Ti-6Al-4V alloy substrates using hot filament chemical vapor deposition. The coatings were developed under optimized plasma-enhanced chemical vapor deposition conditions. Their characteristics were assessed through a combination of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and linear reciprocating tribological testing using silicon carbide (SiC) ball counter faces. XRD patterns confirmed the formation of nanocrystalline diamond layers, with prominent reflections corresponding to the (111), (220), and (311) planes. The suppression of diffraction signals from the underlying titanium alloy suggested uniform and complete coating coverage. Raman spectra showed a sharp sp3 carbon peak at 1332 cm−1, along with D and G bands typical of graphitic structures, indicating the presence of structural changes associated with boron doping. Friction and wear testing demonstrated a notably low coefficient of friction (∼0.0189) and a reduced wear-rate (∼4.02 × 10−5 mm3/N · min), marking a sixfold improvement over the uncoated alloy. Post-test SEM analysis revealed a dense, crack-free surface without signs of delamination. EDX analysis supported this observation, showing high carbon content (∼91.8%) and minimal detection of substrate elements. Furthermore, the wear track depth (110.4 µm) and SiC ball scar diameter (∼810 µm) were both significantly reduced in coated samples. These findings highlight the potential of boron-doped diamond coatings to enhance the surface durability, wear resistance, and mechanical stability of titanium-based materials, particularly for demanding applications such as biomedical implants.

Diamond coatings feature a variety of intriguing properties, such as high thermal conductivity, hardness, mechanical and chemical resistance, and tunable electrical conductivity. A variety of applications for this material have emerged. However, interfacial problems hinder the development of these applications. The adhesion of diamond coatings is of pivotal importance for the service life and performance of diamond coatings. Poor adhesion stems from several issues, for instance, a mismatch of thermal expansion coefficient (TEC) of the diamond and the substrate, poor nucleation of diamond, detrimental effects of elements in the substrates, poor bonding between the diamond coating and the substrate, and etching or degradation of the substrate during diamond deposition. The specific challenges depend on the substrate to be coated and the envisaged application. This review aims to introduce and explain the challenges encountered during thin diamond deposition on non-diamond substrates and delineates strategies to overcome issues related to poor adhesion and diamond film delamination. These strategies include pretreatment processes, such as changing the roughness of the substrate, interlayers, and advanced nucleation strategies, and methods during diamond film deposition, such as multilayer strategies. To complete the review, we provide a brief discussion of unanswered research questions.

Surface topography and chemistry at the biomaterial interface play a decisive role in guiding protein adsorption and influencing cellular interactions. Here, is described a bottom-up approach to synthesize hierarchical diamond topographies with surface features at nano- and microscale with the potential to tailor biomaterial interactions at protein and cellular scales, respectively. This method enables direct control of surface topographical features during the synthesis, without the need for post-deposition modifications. It is shown that hierarchical diamond surfaces can modulate the adsorption of extracellular matrix proteins at nanoscale while altering cellular outcomes, including changes in cell adhesion, spreading, and mechanotransduction. The findings show that diamond surfaces containing nanoscale features with hydrophilic chemistry enhance focal adhesion organization and promote nuclear translocation of yes-associated protein 1 (YAP), a key mechanosensitive transcriptional regulator. This work demonstrates that hierarchical diamond coatings can synergistically tune protein-material interactions and cell behavior, providing a blueprint for next-generation orthopedic implants with improved integration potential.

Finishing and polishing (FaP) are essential procedures that significantly affect the long-term clinical performance of composite restorations; however, their efficacy under varying environmental conditions remains insufficiently elucidated. This study aims to evaluate the impact of dry, wet, and combined FaP sequences on surface roughness (Ra) and microleakage of composite restorations. A total of 57 premolars were randomly assigned to five groups: Control (Cg, n = 11), dry (Dg, n = 12), wet (Wg, n = 12), dry-followed-by-wet (DfWg, n = 11), and wet-followed-by-dry (WfDg, n = 11) group. Finishing was performed in all except Cg using a specified four-step sequence, i.e., fine diamond bur, white stone, and fine and extra-fine Sof-Lex discs. Surface roughness was measured using a profilometer, while dual microleakage evaluation was performed by recording microleakage scores (Ms) under a stereomicroscope (40×), and actual microleakage depths (Md) using a Tool Maker's microscope (30×). Statistical analysis was conducted using the Kruskal-Wallis and Mann-Whitney tests. Intergroup comparisons revealed no significant differences in Ra values (p = 0.136). However, statistically significant differences were observed in Ms and Md values along both the occlusal (p = 0.002) and gingival margins (p = 0.000). Pairwise comparisons showed significantly smoother surfaces in Wg vs Dg (p = 0.04), with additional significant differences in microleakage between Cg-Dg, Cg-DfWg (both margins), and Wg-DfWg (gingival margin). The finishing of composite restorations under wet environmental conditions is somewhat beneficial with respect to surface roughness and microleakage. This study describes the use of a standardized approach to assess the influence of varied environmental conditions on FaP outcomes. The findings provide clinically relevant insights that may further improve procedural efficiency, optimize surface quality, and enhance the longevity of composite restorations.

Diamond coatings with three distinct surface textures, namely spherical, pyramidal, and prismatic morphologies, were fabricated using the hot-filament chemical-vapor deposition (HFCVD) method. Scanning electron microscopy (SEM) was employed to analyze the surface morphological characteristics and differences among the coatings. Raman spectroscopic analysis further confirmed that all three diamond films exhibited excellent deposition uniformity and high crystalline quality. A three-dimensional optical microscopy system was used to measure the surface roughness values, which were determined to be Ra 0.423 μm, Ra 0.515 μm, and Ra 0.809 μm, respectively. An HFCVD diamond-coated tool was innovatively employed for the lapping of sapphire wafers, enabling a systematic investigation of the tribological behavior during the lapping process. Based on the experimental results, three morphological material removal models were established. The study demonstrates that the spherical diamond coating achieves a superior surface finish (Ra 0.22 μm) due to its continuous multi-point contact geometry, governed by the agglomerated nanocrystalline structure. Sample 3 had the highest removal rate of 24.3 μm/min. This is related to its surface morphology characteristics and is also due to the two-body contact between the diamond-coated tool and sapphire, offering a high-efficiency alternative for precision machining.

Aiming at the key problems of the material removal rate and surface integrity of existing tools in the lapping of sapphire hard and brittle crystals, an efficient lapping tool has been developed to explore a new process for HFVCD (hot filament chemical vapor deposition) diamond tools to efficiently lap sapphire wafers. With the premise of ensuring the surface roughness of the wafer is Ra ≤ 0.5 μm, the material removal rate is increased to more than 1 μm/h. To explore a high-efficiency lapping process for sapphire wafers using HFCVD diamond tools. The influence of key preparation parameters on the surface characteristics of CVD (chemical vapor deposition) diamond films was systematically investigated. Three types of CVD diamond coating tools with distinct surface morphologies were fabricated. These tools were subsequently employed to conduct lapping experiments on sapphire wafers in order to evaluate their processing performance. The experimental results demonstrate that the gas pressure, methane concentration, and substrate temperature collectively influenced the surface morphology of the diamond coatings. The fabricated coatings exhibited well-defined grain boundaries and displayed pyramidal, prismatic and spherical features, corresponding to high-quality microcrystalline and nanocrystalline diamond layers. In the lapping experiments, the prismatic CVD diamond coating tool exhibited the highest material removal rate, reaching approximately 1.7 μm/min once stabilized. The spherical diamond coating tool produced the lowest surface roughness on the lapped sapphire wafers, with a value of about 0.35 μm. Surface morphology-controllable diamond tools were used for the lapping processing of the sapphire wafers. This achieved a good surface quality and high removal rate and provided new ideas for the precision machining of brittle hard materials in the plane or even in the curved surface.

Diamond and diamond-like carbon (DLC) coatings are widely employed for their exceptional mechanical, thermal and chemical properties, but their industrial application is often limited by weak adhesion to metallic substrates. In this work, we employ a high-throughput ab initio approach to systematically investigate the adhesion of diamond/metal interfaces, combining a set of technologically relevant metals (Al, Ag, Au, Cr, Cu, Fe, Ir, Mg, Mo, Pt, Rh, Ti, V, W, Zn) with the C(111), C(111)-2 × 1 (Pandey reconstructed), C(110), C(100) surfaces, that are most common in diamond and are representative of different types of bonds present in DLC. Thanks to our automated and accurate computational protocol for interface construction and characterization, databases are populated and relevant trends are identified on the effect of surface graphitization, ability to form carbides and metal reactivity on carbon film adhesion and delamination strength. Beyond capturing trends, our workflow yields predictive insights. Indeed, we found that adhesion energy scales with the geometric mean of the constituent surface energies, providing a simple descriptor for rapid screening; while comparing the work of separation with the metal’s cohesive energy anticipates the fracture location under tensile loading. A novel method based on the radial distribution function g ( r ) analysis is introduced to identify when contact with a metal drives rehybridization of surface carbon from sp 2 to sp 3 , the structural signature of improved resistance to delamination. These structural changes are mirrored by an electronic rearrangement at the interface, quantified by a charge-redistribution descriptor that strongly correlates with adhesion.

Microstructural characterization and Tribological properties of silicon-doped diamond coatings on surface-textured cemented carbide spheres

Fabrication and tribological optimization of diamond coatings on laser-textured zirconia substrates

Tribological performance of quenched diamond coatings on pure titanium under dry sliding conditions

There is no current evidence in the literature that clearly guides clinicians in selecting the most effective polishing protocol in lingual orthodontics. This study aimed to compare the reduction of adhesive remnants after polishing customized lingual composite brackets using tungsten carbide, fine diamond, and Arkansas burs. A total of 504 extracted teeth were included and randomly assigned to three groups according to bur type (n = 168). Brackets were bonded and debonded following a standardized protocol, and digital scans were obtained before and after polishing. Each bur was tested at both low speed (contra-angle) and high speed (turbine). Tungsten carbide burs produced the greatest reduction in cement thickness under both rotary conditions. At low speed, the mean Pre-Post thickness differences were 0.64 mm (TUN), 0.31 mm (ARK), and 0.37 mm (DIA). At high speed, differences were 0.45 mm (TUN), 0.39 mm (ARK), and 0.41 mm (DIA). Statistically significant differences were found between the tungsten carbide group and both the Arkansas and diamond groups (p < 0.005), with no differences between the latter two. Tungsten carbide burs removed significantly more adhesive than Arkansas and diamond burs, regardless of rotary speed. These findings support clinical decision-making by helping optimize polishing protocols in lingual orthodontics.

The study focuses on identifying the specific mechanisms of the FR4 fiberglass composite milling process using tungsten carbide end mills with wear-resistant diamond-like and diamond coatings. The processing was carried out at cutting speeds from 115 to 300 m/min and feed of 0.075 and 0.15 mm/tooth. At the same time, the vibroacoustic signal was recorded in three formats: changes in the RMS value and the amplitude of the acoustic emission in the low-frequency and high-frequency ranges, as well as the parameter Kf, which is the ratio of the RMS amplitudes of the signals in the low-frequency and high-frequency ranges. It is shown that the coating material has a predominant effect on the surface roughness. The minimum roughness value was RA = 0.2 µm for the case of a diamond-coated tool. In addition, the coating improves processing performance by increasing the cutting speed for tools with DLC by 1.3 times and for tools with diamond coating by 1.7 times, provided that the RA increases slightly but does not exceed 0.36 µm. When processed with an uncoated instrument, the mill captures the fiber, bends it and breaks it into bundles, creating grooves. The mechanism of glass fiber destruction by a DLC mill is similar, with the difference that the length of the fragmented fiber sections is noticeably reduced due to reduced friction. The mechanism of cutting fiberglass with a diamond-coated milling cutter is significantly different. There are characteristic scratches on the worn sections of the fiber, and there are no signs of destruction of the composite between the matrix and the fiber. Studies of vibration signals have shown that frequency ranges up to 20 kHz and from 33 to 48 kHz are informative enough to diagnose the fiberglass milling process. The most significant values of the Kf parameter were observed at large amplitudes of low-frequency vibrations, typical for processing with uncoated and DLC milling cutters. The lowest Kf values were obtained using diamond-coated milling cutters. A correlation was found between the values of the Kf parameter and the roughness values of the treated end surface of the fiberglass plate.

Could diamond coatings provide a better osseo-interface for 3D-printed titanium implants?

Corrosion-resistant coatings are essential for extending the service life of magnesium alloys. In this work, quenched-produced diamond (Q-dia) films were deposited on Mg-Ca alloy substrates by physical vapor deposition using high-purity graphite (99.999%) as the carbon source. To enhance interfacial bonding, three thin interlayers (Al, Ti, and TiC) were examined as interfacial layers. Among them, the TiC interlayer effectively enabled successful adhesion and produced a uniform coating. Scanning electron microscopy (SEM) revealed dense nanodiamond grains growth with a compact, a defect-free cross section. Electrochemical analyses demonstrated that Q-dia coatings markedly enhanced the corrosion resistance of Mg-Ca alloy in 3.5 wt% NaCl solution, increasing the corrosion resistance from 0.336 kΩ.cm² to 1.78 kΩ.cm². This enhancement is attributed to the highly compact microstructure of Q-dia grains containing both sp 2 - and sp 3 hybridized -carbon phases, as confirmed by Raman spectroscopy. These findings highlight Q-dia as promising protective coating films for improving the corrosion resistance and durability of magnesium-based alloys.

Improving the interfacial stability of graphite anodes remains a major challenge for extending the lifetime of lithium-ion batteries. In this study, ultrananocrystalline diamond (UNCD) and nitrogen-incorporated UNCD (N-UNCD) coatings were employed as protective layers to enhance the electrochemical and mechanical robustness of graphite electrodes. Half-cells were cycled for 60 charge–discharge cycles, and their behavior was examined through electrochemical impedance spectroscopy (EIS), Distribution of Relaxation Times (DRT), and Equivalent Circuit Modeling (ECM) to disentangle the characteristic relaxation processes. The potential–capacity profiles exhibited the typical LiC12–LiC6 transition plateaus without any additional features for the coated electrodes, confirming that the UNCD and N-UNCD films do not participate in lithium storage but serve as chemically inert and electrically stable interlayers. In contrast, the uncoated reference graphite anodes showed greater capacity fluctuations and increasing interfacial impedance. DRT and ECM analyses revealed four consistent relaxation processes—electronic transport (τ1), ionic transport through the electrolyte (τ2), Solid Electrolyte Interface (SEI) response (τ3), and lithium intercalation (τ4). The τ2 process remained invariant, whereas τ3 and τ4 were markedly stabilized by the UNCD and N-UNCD coatings. UNCD exhibited the lowest SEI-related resistance and the most stable charge-transfer kinetics, while N-UNCD displayed an initially higher τ3 resistance followed by progressive self-stabilization after 20 charge/discharge cycles, linked to reorganization of nitrogen-rich grain boundaries. Overall, polycrystalline diamond coatings—particularly UNCD—proved to be highly effective in suppressing SEI layer growth, minimizing impedance rise, and preserving lithium intercalation efficiency, leading to enhanced long-term electrochemical performance. These findings highlight the potential of diamond-based protective layers as a durable and scalable strategy for next-generation graphite anodes.

Diamond is widely considered for high-temperature applications in extreme environments due to its exceptional hardness, thermal conductivity, and chemical inertness. However, its performance is limited by surface oxidation when exposed to high-temperature oxidative environments. Here, we comprehensively investigate the surface oxidation failure of diamond nanoneedles under oxygen atmosphere, electron beam irradiation and thermal activation. The dynamic oxidation process is monitored by spherical aberration-corrected environmental transmission electron microscopy (ETEM). Our results reveal an anisotropic oxidation behavior, where the reaction front preferentially propagates along the {111} and {001} through progressive degradation. This crystallographic selectivity highlights inherent differences in surface stability and reactivity among diamond facets. Initially, a continuous amorphous carbon coating layer provides protection to the diamond surface by acting as a diffusion barrier. However, once the layer thins below a critical threshold (∼10.2 ± 0.5 nm), it undergoes topological fragmentation, exposing the diamond to anisotropic oxidation, which proceeds preferentially along the (111) and (001) planes. Additionally, we demonstrate that the oxidation rate is significantly enhanced by the synergy of localized electronic excitation and thermal effects, which effectively lowers the activation energy barrier. These atomic-scale insights establish a mechanistic foundation for designing oxidation-resistant diamond coatings and provide experimentally accessible routes for validating and translating ETEM-derived mechanisms into engineering practice.

The accuracy of intraoral scanning is crucial for the long-term survival of indirect restorations. It remains unclear if preparation protocols, surface characteristics, and humidity play a role in the quality of an intraoral scan. The purpose of this in vitro study was to assess the impact of margin preparation on both dentin and enamel using different finishing protocols. These assessments were conducted on specimens stored in both dry and wet environments, with a specific focus on evaluating their influence on the accuracy of intraoral scans. Six maxillary canines were prepared using three different sequences. In the first sequence, a coarse diamond rotary instrument (DC) was used. In the second, DC was followed by a fine grit diamond rotary instrument (DCDF). In the third, the DC was followed by a tungsten carbide rotary instrument. Margins were scanned 10 times using an intraoral scanner (TRIOS 3; 3Shape A/S) compared to a laboratory scanner (D2000; 3Shape A/S). Accuracy was determined by measuring precision and trueness (Geomagic Control; Hexagon). To assess the impact of 3-dimensional (3D) topography on accuracy, roughness was measured using a laser microscope (Lext OLS 4000; Olympus). The data were analyzed using the Levene test, followed by a 3-way ANOVA with Bonferroni post hoc testing to assess the effects and interactions of surface finish, environment, and tissue on the outcomes (α=.05). Improved precision was observed in enamel (15.7µm) compared to dentin (24.3µm) specimens (P<.001). Furthermore, the environment had a significant impact on accuracy (P<.001). Higher precision and trueness (P<.001) were observed for dentin in dry (18.3µm) compared to wet (37.3µm) conditions. The use of fine grit diamond rotary instruments improved precision and trueness for dry dentin (DC/DCDF P=.017; DC/DCCF P=.005; DCDF/DCCF P>.999), while no difference was detected for dry enamel (DC/DCDF P=.966; DC/DCCF P=.822; DCDF/DCCF P=.519). The use of a second finishing rotary instrument decreased Sa (µm) for dentin (DC/DCDF/DCCF) (7.11/5.63/4.53), whereas enamel values were similar (7.94/8.53/9.97). Surface roughness, tooth substrate, and scanning environment (or humidity conditions) were found to influence the accuracy of intraoral scans.