To investigate comparatively the changes in surface roughness and surface microhardness of resin composites applied with traditional incremental layering technique and bulk-fill resin composites after erosive/abrasive applications. In this laboratory study, three conventional resin composites with different contents: Filtek Z250 (FZ), Filtek Ultimate (FU), Clearfil Majesty Esthetic (CME), and four bulk-fill resin composites: X-tra fil (VXF), Filtek One Bulk Fill (FOB), QuiXfil (QXF), and Tetric N-Ceram Bulk Fill (TNC) were used. While preparing the test specimens, resin composites were applied to 8 mm diameter and 2 mm height round plexiglass molds (n= 15) and polymerized. Each specimen was polished. Then, the baseline surface roughness (R0) and surface microhardness (H0) values of the specimens were measured. Each group had been exposed to erosive/abrasive cycle for 10 days. After the cycle, by measuring the roughness (R1) and microhardness (H1) values of the specimen, the alterations of the surface properties were investigated. After the baseline and erosive/abrasive cycles of the specimens, the surface analyses were performed with scanning electron microscopy. One-way ANOVA test, Tukey's post hoc test, and t-test were used for statistical analysis. Differences at the P< 0.05 level were considered statistically significant. There was no statistically significant difference between the H0 values of the FU, VXF, QXF, and FZ groups, and the H0 values of these groups were higher than the other groups (P< 0.05). After the erosive/abrasive cycle, there was no significant difference in the H1 values of only the FZ and VXF groups (P> 0.05). When the R0 values were examined, there was no significant difference between the FOB, FU, FZ, and TNC groups (P> 0.05), and the R0 values of these groups were statistically lower than the other groups (P< 0.05). A statistically significant increase was observed in the R1 values of all composite materials examined after erosive/abrasive applications (P< 0.05). In the SEM findings, erosive/abrasive applications caused degradation of both the organic matrix and surface properties of inorganic fillers. According to the results of this laboratory study, erosive and abrasive cycles negatively affected the surface microhardness and roughness of conventional and bulk-fill composites at different rates and varied depending on the structural properties. However, the surface roughness of Filtek Ultimate and Filtek One Bulk Fill, both with nanofill structure, was less affected by combined erosive and abrasive cycles.
Lithium disilicate glass-ceramics (LDGCs) have become one of the most widely used dental prosthesis materials in clinical practice due to their excellent esthetics, biocompatibility, and enamel-like wear resistance. However, their inherent brittleness, limited mechanical strength, and progressive wear under long-term service have restricted their application in high-stress posterior regions. Herein, this study aims to develop zirconia (ZrO2)-reinforced LDGCs and systematically investigate the effects of ZrO2 content on microstructure evolution and mechanical, translucency, tribological, and biological performance. ZrO2-reinforced LDGCs (LDGCxZ, where x = 0, 2, 4, 6 mol%, designated as LDGC, LDGC2Z, LDGC4Z, and LDGC6Z) with varying ZrO2 contents were fabricated via a melting-derived powder processing route combined with digital light processing, debinding, and sintering. The LDGCxZ samples were systematically characterized for their microstructural evolution, mechanical properties, translucency, tribological behavior, and biological performance through biaxial flexural strength testing, aging resistance testing, Weibull two-parameter distribution analysis, Vickers hardness testing, fracture toughness analysis, nanoindentation testing, and tribological evaluation. Furthermore, hemocompatibility, cytocompatibility, and in vivo biological responses were assessed using hemolysis assays, CCK-8 assays, live/dead staining, phalloidin staining, subcutaneous implantation in a rat model, and comprehensive biosafety evaluation. 4 mol% ZrO2 doping optimally refines the crystalline structure, creating a homogeneous dual-phase of Li2Si2O5 and Li2SiO3 that effectively minimizes internal defects, while excessive doping (6 mol%) leads to abnormal grain growth and porosity formation. Impressively, the sintered LDGC4Z sample (4 mol% ZrO2) exhibited exceptional comprehensive properties: a flexural strength of ∼294 MPa, fracture toughness of ∼4.1 MPa m1/2, elastic modulus of ∼111.4 GPa, and Vickers hardness of ∼644 HV, and a 150% enhancement in the translucency parameter, alongside superior anti-aging resistance and tribological behavior closely matching that of natural enamel. The LDGC4Z sample also confirmed excellent hemocompatibility, favorable cytocompatibility with human gingival epithelial cells, and stable tissue integration in subcutaneous implantation models. Collectively, the LDGC4Z sample exhibited balanced improvements in mechanical properties, translucency, tribological resistance, and biological safety, while suppressing LTD through microstructural refinement, stress engineering, and crystallization control. Significance This study overcomes the limitations of conventional processing routes by integrating DLP 3D printing technology with a ZrO2 compositional regulation strategy within the LDGC system. A novel LDGC system that combines printability, microstructural controllability, and mechanical compatibility was successfully established, providing an essential theoretical foundation and process framework for the development of high-performance LDGC materials for dental restorations.
The aim of this study was to evaluate the influence of prosthetic substrate type, resin cement shade, and opaquer liner application on the translucency and color matching of translucent zirconia- and lithium-based ceramics. Four A2-shade zirconia materials (Katana HTML Plus, STML, UTML, and YML), with and without an opaquer liner, lithium disilicate ceramics (Amber Mill LT and HT), and zirconia-reinforced lithium silicate (Celtra Duo) were investigated. Monolithic crowns and standardized rectangular specimens were fabricated using CAD/CAM technology and cemented with neutral, warm-shade, and opaque try-in pastes onto A2-shade composite resin and cobalt-chromium substrates. Color measurements were performed using a digital colorimeter based on the CIE L*a*b* system. Translucency parameters (TPs) and color differences (ΔE) relative to the A2 reference shade were calculated. Lithium-based ceramics exhibited significantly higher translucency than zirconia materials. Application of the opaquer liner on intaglio surface of crowns reduced their translucency. On A2-shade substrates, translucent zirconia luted with neutral or warm-shade paste demonstrated the most favorable color compatibility. In contrast, opaque try-in paste resulted in clinically unacceptable color deviations and loss of optical depth. On metallic substrates, most materials exhibited pronounced gray discoloration and substantial color mismatch, particularly lithium disilicate ceramics. These findings indicate that ceramic type, substrate color, opaquer liner application, and resin cement shade significantly influence the optical performance and final color outcome of all-ceramic restorations.
This study presents an innovative approach to improving the fracture toughness and sustainability of hybrid epoxy composites by synergistically reinforcing Gossypium (cotton) and E-glass fibers with silicon carbide (SiC) microfillers (20-50 μm, 0-15 wt%). Unlike conventional natural fiber composites limited by poor interfacial bonding, this work optimizes the hybrid laminate architecture and filler dispersion to achieve enhanced crack resistance. Composite laminates were fabricated via a controlled hand lay-up and compression molding process, followed by Mode I fracture toughness (GIC) and compact fracture toughness (KIC) testing per ASTM D5528 and D5045 standards using a 30 kN Instron 3365 frame. Results demonstrated that 15 wt% SiC composites attained the highest GIC = 0.82 kJ/m², while 10 wt% SiC achieved the maximum KIC = 1.52 MPa√m, confirming optimal energy dissipation through crack deflection, bridging, and fiber pull-out suppression. SEM fractography revealed uniform filler dispersion and strong interfacial adhesion with minimal voids, validating the improved load transfer and reduced delamination. Compared to unfilled controls, SiC-filled hybrids exhibited a 47% increase in GIC and 38% improvement in KIC, aligning with literature benchmarks for automotive-grade composites. The innovative combination of renewable cotton fibers with high-strength glass and ceramic fillers offers a sustainable, high-toughness material suitable for automotive body panels, undertrays, and interior structures where lightweight and damage tolerance are essential.
Nanocomposites of modified poly (methyl methacrylate) (C-PMMA) reinforced with zirconium dioxide (ZrO2) and cerium dioxide (CeO2) nanoparticles were prepared through in situ polymerization. Their dielectric and radiation shielding properties were also evaluated. We used p-phenylenediamine (p-PDA) to modify the PMMA matrix to make it more rigid and stable at high temperatures. Ceramic nanoparticles were incorporated into the composite at various loadings ranging from 5 to 40 wt%. Structural, morphological, and thermal analyses using FTIR, XRD, SEM-EDX, and TGA all showed strong interfacial adhesion and even distribution of nanoparticles. The composites showed enhanced thermal stability, with residual mass rising to 25-30% and onset degradation temperature increasing to ~ 305 °C compared to 280 °C for pristine C-PMMA. Dielectric analysis at 110 °C shows remarkable improvement in electrical properties. The dielectric constant (ε') increased from ~ 3.0 for pristine C-PMMA to ~ 4.6 for the 5 wt% ZrO2 composite at 500 kHz, corresponding to an improvement of approximately 53%. Moreover, the AC conductivity improved from ~ 6-7 µS (C-PMMA at 1000 kHz) to ~ 25-26 µS for the 5 wt% ZrO2 composite, which is almost 3-4 times better. Composites of CeO2 showed mild yet systematic enhancement, with a conductivity of approximately 8 µS at 40% filler loadings. Radiation attenuation simulated experiments conducted with assistance from the Phy-X/PSD software revealed that both CeO2- and ZrO2-filled nanocomposites. The linear attenuation coefficient confirmed the great improvement in low-energy photon-shielding capability at high ceramic loadings at 0.015 MeV, which increased by approximately 37.5 cm-1 for the C-PMMA/ 40% wt. CeO2 and 9.95 cm-1 for C-PMMA/ 40% wt. ZrO2 than pristine C-PMMA, while the corresponding half-value layer at 8 MeV decreased by approximately 39%. The fabricated composites could be used as promising materials for components such as housings, encapsulation layers, and support structures in electronic modules that operate close to radiation sources, where moderate radiation shielding, electrical insulation, and decreased weight are all needed at the same time. However, further verification of mechanical dependability and experimentally determined shielding efficacy will determine their ultimate usefulness.
Separators have evolved from passive polymeric barriers into multifunctional components that critically govern the performance, safety, and lifetime of liquid and quasi-solid lithium rechargeable batteries. This Review provides a comprehensive analysis of separator materials and architectures spanning commercial polyolefins and their ceramic coatings, high‑temperature polymers (PI, PEEK), nanofiber and bio‑derived membranes, and cross-linked gel/polymer-ceramic composites for quasi-solid systems. Design principles linking pore size, porosity, tortuosity, wettability, and Li+ transference to ionic conductivity and rate capability are systematically discussed, alongside mechanical and thermal requirements such as puncture resistance, dimensional stability, shutdown behavior, and flame retardance. We compare major fabrication routes-including dry and wet stretching, phase inversion, electrospinning, ceramic/oxide coating, UV/thermal crosslinking, and vacuum filtration/solution casting-and relate their process windows to separator microstructure, electrochemical performance, and scalability. Separator-electrolyte-anode interactions are analyzed with emphasis on dendrite suppression, flux homogenization, and interface stabilization in lithium‑metal and quasi‑solid cells. Finally, market and techno‑economic trends are summarized, highlighting the trade‑offs between advanced functionality and roll‑to‑roll manufacturability, as well as emerging directions toward intelligent (advanced) separators and PFAS‑free, recyclable architectures. This review outlines quantitative targets and design strategies needed to translate next‑generation separator concepts into safe, high‑energy, and commercially viable lithium battery technologies.
Natural fibre-reinforced polymer composites are increasingly explored for sustainable structural applications but only limited information is available on the mechanical performance of composites reinforced with Vachellia nilotica, Prosopis juliflora and Vachellia leucophloea. This study aims to investigate whether the incorporation of these novel fibres with ceramic fillers can significantly improve the mechanical (elastic and tensile) properties of epoxy composites. The testing samples (15) are fabricated, containing hexagonal boron nitride, alumina and silicon carbide using the hand layup method and tested according to ASTM standards through impulse excitation and tensile testing. A Response Surface Methodology-Box-Behnken design combined with ANOVA / regression analysis is employed, followed by multi-response optimisation using Grey Relational Analysis. The optimal composite containing 4 wt.% Vachellia nilotica fibre with SiC filler exhibits a Young's modulus of 5.49 GPa, shear modulus of 2.18 GPa and tensile strength of 28.7 MPa, with confirmation errors below 5%. The model exhibits good adequacy (R2 = 90.08%, Adj. R2 = 82.64%) with acceptable predictive capability (Pred. R2 = 62.70%) for optimisation. SEM results show that the SiC-filled composite possesses uniform dispersion and strong interfacial bonding, leading to superior mechanical performance. These results demonstrate that the proposed natural fibre hybrid composites provide enhanced stiffness and strength, confirming their suitability for lightweight structural and electrical insulation applications.
Piezoelectric ceramics, such as K0.5Na0.5NbO3 (KNN), can be designed as electrically active biomaterials for the repair and regeneration of damaged tissue, particularly bone. Applied as functional components in tissue scaffolds or implanted devices, the electromechanical properties of piezoelectric bioceramics could be utilized for cellular stimulation to improve the healing of bone defects and implant sites. The microstructural and functional properties of KNN-based ceramic systems can be extensively modified by adjusting the precursor chemistry and synthesis. The effect of these modified systems on in vitro cytocompatibility and cell behavior is investigated in this study. Stoichiometric, 0.2 mol% alkali-excess, 0.2 mol% Nb-excess, and hybrid synthesis KNN ceramics were evaluated in unpolarized and polarized states. Bulk piezoelectric response was maintained up to 14 days in media. Cell spreading, morphology, metabolic activity, and reactive oxygen species (ROS) generation of MG-63 human osteoblast cells were assessed on each KNN system. All KNN compositions investigated displayed no cytotoxic effects, with comparable performance to titanium implant alloy (Ti4Al6V) controls. Alkali-excess and hybrid synthesis KNN systems exhibited increased stability over stoichiometric and Nb-excess KNN, largely due to the suppression of hygroscopic secondary phases in synthesis. This work concludes that these modified KNN systems present excellent candidate materials for active bioceramics with piezoelectric functionality.
This study explores the valorization of ceramic waste (CW) and waste tire particles in the development of eco-friendly cementitious tiles for outdoor roof shielding applications. CW, sourced from industrial byproducts and demolition debris, offers promising hydraulic properties and cost-effectiveness. Two waste samples, collected during the renovation of sanitary facilities in an aged building and waste iron powder (WIP) were incorporated into cement formulations comprising Portland cement, fine aggregates, water, and recycled materials. The waste components were characterized via particle size distribution analyses which was found in the order of 34.15 μm for waste wall ceramic while it was 49.06 μm for waste floor one. The chemical composition analysis using X-ray fluorescence (XRF) was measured. The bulk density after a cure period of 28 days, water absorption was also evaluated. The compressive strength and flexural strength data revealed enhancement by the addition of WIP particles. This enhancement is attributed to the strong interfacial bonding between WIP particles and the cementitious matrix. Powder X-ray diffraction was used to measure crystalline phase composition. The results demonstrate that ceramic and rubber wastes reduce density and increase water absorption due to enhanced porosity, while the inclusion of WIP significantly improves matrix densification, mechanical strength, and electrical conductivity. Composites containing 10 wt% WIP exhibited optimal performance, achieving enhanced compressive and flexural strengths. Electrical conductivity measurements revealed values ranging from 10− 13 to 10− 11 S/cm, aligning with the requirements for antistatic applications. Consequently, the tiles are recommended for use as antistatic roof shielding materials. Besides, Electromagnetic interference (EMI) shielding tests demonstrated that samples incorporating a metal mesh achieved attenuation levels exceeding 20 dB, effectively blocking over 99% of incident electromagnetic waves. Further enhancement was observed with the addition of waste conducting particles (WIP), suggesting that composites integrating both WIP and metal mesh can achieve EMI shielding efficiencies up to 99.999%, making them suitable for industrial and commercial applications demanding high-performance shielding. The developed tiles comply with Egyptian and European standards for external cement tiles, demonstrating their suitability for sustainable construction applications, particularly for roofing and flooring in environments exposed to electromagnetic pollution. This work highlights an effective pathway for converting multiple waste streams into high-value, multifunctional building materials.
In this work, micro/nano-scale (TiB2 + TiC)/Al composites with reinforcement contents ranging from 0 to 30 wt.% were fabricated by the combination of Ti-B4C reactive sintering and spark plasma sintering (SPS). The results indicate that a sintering temperature of 1400 °C is essential for achieving a complete reaction between Ti and B4C, successfully producing a bimodal TiB2-TiC reinforcement consisting of nano-scale and micro-scale particles. Microstructure analysis reveals that the addition of micro/nano-scale TiB2 and TiC ceramic particles significantly refines the grain size of the Al matrix from 11.52 μm in pure Al to 1.09 μm in the 30 wt.% (TiB2 + TiC)/Al composite. As the TiB2 and TiC contents increase, Vickers hardness and compressive yield strength increase progressively, while the uniform compressive plastic strain first increases and then decreases. The 20 wt.% (TiB2 + TiC)/Al composite demonstrates the optimal comprehensive properties, with a compressive yield strength of 196.4 ± 6.1 MPa, an ultimate strength of 914.6 ± 20.1 MPa, and a uniform plastic strain of ~73.2%, as well as minimal wear rates of (3.143 ± 0.194) × 10-4 mm3/(N·m), 1.676 ± 0.251× 10-3 mm3/(N·m) and (3.093 ± 0.335) × 10-3 mm3/(N·m) at 1 N, 3 N, and 5 N, respectively. This improvement stems from the combined effects of grain refinement, dispersion strengthening, enhanced load-bearing capacity and reduced adhesive wear via the TiB2 and TiC reinforcements.
The purpose of the current in vitro study was to evaluate and compare the marginal adaptation and fracture resistance of CAD/CAM VITA ENAMIC hybrid ceramic and, 3D printed Nanoksa G-PLUS high-performance polymer endocrown composite restorations constructed for endodontically treated teeth “EET”; considering two distinct coronal preparation designs: standardized anatomic and butt joint. A total of 40 freshly extracted intact human permanent mandibular molars were endodontically treated to receive endocrowns. Specimens were randomly divided into two equal groups “n = 20 each”: Group1 “G1” received 3D printed Nanoksa G-PLUS high-performance polymer, and Group2 “G2” received CAD/CAM VITA ENAMIC hybrid ceramic endocrown restorations. Each main group was further subdivided into two equal subgroups “n = 10 each” based on the coronal preparation design: standardized anatomic “G1A, G2A” and butt joint “G1B, G2B”. All endocrowns were adhesively luted with their respective manufacturer-recommended resin cements. Subsequently, all specimens underwent simulated aging through a chewing simulator and thermo-cycling (CSTC device, CS-4, SD Mechatronik, Germany). Marginal adaptation was quantitatively assessed by measuring the marginal gap distance using a USB Digital stereomicroscope (U500x Digital Microscope, Guangdong, China). Fracture resistance was determined using a universal testing machine (Model 3345; Instron Industrial Products, Norwood, MA, USA). Statistical analysis was performed using IBM SPSS Statistics (version 26), employing a two-way ANOVA followed by Tukey’s post-hoc tests, with significance set at P < 0.05. VITA ENAMIC specimens exhibited significant higher fracture resistance values; (p < 0.0001) and significant lower marginal adaptation (higher marginal gap values) than those of Nanoksa G-PLUS. Successful serviceability of recent endocrown restorations “Nanoksa G-PLUS and VITA ENAMIC” seems critically influenced by the material of construction and the technology of its fabrication. VITA ENAMIC endocrowns combined with anatomic preparation designs yielded the highest fracture resistance, while the Nanoksa G-PLUS endocrowns with butt joint preparation design exhibited the least fracture resistance of all subgroups. Understanding the performance characteristics of these advanced technology of restorative biomaterials, and adhesive bonding systems and preparation designs is crucial for optimizing the clinical outcomes and enhancing serviceability and longevity of endocrown restorations in posterior teeth.
To compare the surface roughness (Ra), stainability, and translucency of a ceramic composite concentrate-reinforced interim resin with its corresponding non-reinforced formulation and with a ceramic-filled resin indicated for definitive use after coffee thermal cycling. Disk-shaped specimens (Ø10 × 1 mm) were additively manufactured from an unfilled resin for interim use (AM-INT; FREEPRINT Temp, Detax), the same resin for interim use reinforced with a 30 wt% commercially available ceramic composite concentrate (AM-R-INT), and a ceramic-filled resin indicated for definitive use (AM-DEF; Crowntec, Saremco Dental AG) (n = 12). The Ra values of each specimen were measured before and after polishing. Color coordinates were measured after polishing, followed by 10,000 cycles of coffee thermal cycling, after which both Ra and color measurements were repeated. The color difference (∆E00) caused by coffee thermal cycling and the relative translucency parameter (RTP) of each specimen were calculated. The Ra and RTP data were analyzed with a generalized linear model, while ∆E00 values were evaluated with Kruskal-Wallis and Bonferroni-corrected post hoc tests (α = 0.05). The interaction between the resin type and time point significantly affected the Ra and RTP, while the resin type impacted the ∆E00 (p ≤ 0.015). AM-INT had the highest Ra among the other resins before polishing, and the Ra of each tested resin was higher before polishing than after polishing or coffee thermal cycling (p ≤ 0.006). AM-R-INT had higher ∆E00 than AM-DEF (p < 0.001). AM-DEF had higher RTP than AM-INT after polishing (p = 0.006). However, AM-DEF also had the lowest RTP after coffee thermal cycling, whereas AM-INT had the highest (p ≤ 0.018). AM-R-INT and AM-DEF had reduced RTP after coffee thermal cycling (p ≤ 0.001). All tested resins achieved clinically acceptable Ra after polishing and coffee thermal cycling. AM-DEF exhibited a perceptible but clinically acceptable color change, whereas the other resins showed moderately unacceptable changes, highlighting potential esthetic limitations. The reinforced interim resin (AM-R-INT) exhibited a perceptible translucency difference compared with other resins after polishing, and coffee thermal cycling caused a significant reduction in translucency for both AM-R-INT and AM-DEF, resulting in clinically unacceptable changes. These findings emphasize the importance of considering both material composition and polishing procedures when selecting interim and definitive prostheses, particularly for patients with regular exposure to coffee.
The limited regenerative capacity of bone and peripheral nerve tissues, together with the insufficient bioactivity and immunomodulatory control of commercially available coating materials, drives the development of multifunctional biomaterials capable of modulating cellular and immune responses. Herein, bacterially derived poly(3-hydroxyoctanoate) (P(3HO)) was applied as a biodegradable matrix for nanocomposites incorporating layered double hydroxides (LDHs) and their turmeric (turm)-functionalized counterparts. Nanocomposite films containing 2 wt.% nanofillers were fabricated by solvent casting. Structural and physicochemical analyses confirmed successful functionalization (up to 60 wt.% turm), with a tendency to form microscale agglomerates within the polymer matrix. These agglomerates contributed to heterogeneous surface topography (Ra 0.9-7.9 μm) and governed the structure-property relationship in accordance with the Nanoarchitectonics strategy. Mechanical and surface properties were tunable, especially with a reduction in surface free energy of up to 24% for turm-containing nanocomposites. In vitro studies performed on mouse preosteoblastic (MC3T3-E1) and mouse neuroblastoma × rat glioma hybrid neuronal (NG108-15) cell lines confirmed a lack of toxicity, with cell viability exceeding 70% under both indirect and direct test conditions. All turm-functionalized materials supported cell differentiation and proliferation. However, the most favorable biological response was observed for P(3HO)_Zn/Al-turm, which exhibited enhanced neuronal proliferation of NG108-15 cells. Moreover, this system demonstrated robust immunomodulatory activity, inducing TGF-β1 secretion at ∼1787 pg mL-1 (comparable to the M2 phenotype) while maintaining controlled MMP-2 levels (∼19.9 pg mL-1) for human monocytic-derived macrophages (THP-1). In contrast, Ca/Al-based nanocomposites promoted osteogenic responses in MC3T3-E1 cells but showed lower neuronal proliferation. Importantly, incorporation of nanofillers overcame the intrinsic limitations of neat P(3HO), enabling neuronal growth and differentiation. These findings demonstrate that turm-functionalized P(3HO)/LDHs nanocomposites, designed according to the nanoarchitectonics concept, constitute a versatile platform integrating structural tunability and bioactive immunoregulation, opening remarkable perspectives for advanced coatings targeting bone and nerve tissue regeneration.
The color stability and translucency of contemporary Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) glass and hybrid ceramic materials used for minimally invasive laminate veneers remain a clinical concern, particularly after exposure to aging conditions simulating oral service. The purpose of this in vitro study was to investigate the influence of accelerated artificial aging on the color stability and translucency of ceramic laminate veneers fabricated from different glass and hybrid ceramic materials. A total of 40 composite resin discs (A2 dentin shade, 8.0 mm diameter × 4.0 mm thickness) were fabricated to simulate the normal dentin substrate. They were randomly assigned to four groups (n = 10) according to the ceramic veneering material: (EC) IPS e.max CAD, (CT) Cerec Tessera, (VE) Vita Enamic, and (CS) Cerasmart. Then, 40 disc-shaped ceramic veneers (0.5 mm thickness) were fabricated and adhesively cemented to the substrates. Baseline color and translucency parameters were measured using a digital spectrophotometer. After artificial thermomechanical aging, color differences (ΔE00), using the CIEDE2000 formula and translucency parameter (TP) were calculated. The resulting data were statistically analysed using repeated-measures two-way analysis of variance (ANOVA) test (material × aging), followed by Post hoc Tukey test for multiple-group comparisons and Paired t-test for within-group comparisons, at p-value ≤ 0.05. Artificial aging significantly affected color stability and translucency for all tested materials (p < 0.001). Glass ceramics (EC and CT) demonstrated lower ΔE₀₀ values within clinically acceptable limits, whereas hybrid ceramics (VE and CS), particularly CS, exhibited significantly higher color changes exceeding acceptability threshold. Translucency significantly decreased after aging for all materials (p < 0.001). Artificial thermomechanical aging adversely affected the optical properties of all tested ceramic laminate veneers. The hybrid ceramic materials, particularly CS, were the most affected by aging in terms of color stability, whereas the glass ceramic materials (EC and CT) exhibited superior color stability. A reduction in translucency was observed for all materials after aging.
Injectable hydrogels are considered to be a minimally invasive approach for the regeneration of the dental bone, providing a number of benefits over traditional surgical procedures. These three-dimensional networks can be given in liquid form and undergo in situ gelation, which keeps their high-water content and structural integrity while enabling them to conform to irregular bone defects. This review focuses on the current state of injectable hydrogel systems for dental bone regeneration, strategies of synthesis, and biological performance, focusing on the design of the material and clinical translation. Injectable hydrogels can be broadly classified into two categories: natural polymer-based systems and synthetic polymer-based systems. Natural polymer-based systems include materials such as chitosan, alginate, hyaluronic acid (HA), and protein-based formulations. Synthetic polymer-based systems include polyethylene glycol (PEG), polyvinyl alcohol (PVA), and thermosensitive polymers. Hybrid composite systems combine the mechanical flexibility of synthetic polymers with the bioactivity of natural polymers. Both physical crosslinking techniques (ionic interactions, thermogelation, and hydrogen bonding) and chemical crosslinking techniques (enzymatic catalysis, Schiff base reactions, photoinitiation, and thiol-disulfide exchange) are included in the synthesis and gelation mechanisms, and each has unique benefits concerning mechanical characteristics, degradation kinetics, and biocompatibility. Advanced fabrication methodologies, including fibre integration, bioprinting, and integration of nanotechnology, have enhanced the functional properties of injectable hydrogels. These systems promote osteogenesis, angiogenesis, immunomodulation, and infection control by acting as flexible carriers for growth factors, bioactive ceramics, extracellular vesicles (EVs), and antimicrobial agents. Growth factor-loaded hydrogels have accelerated bone healing and periodontal regeneration in human subjects, according to clinical trials with encouraging results. However, despite the progress, there are limitations in improving the mechanical properties for the oral environment, establishing uniform regulatory frameworks for clinical translation, preserving bioactivity during degradation, and reaching regulated biodegradation rates. Future research should concentrate on building a dual-functional system that combines regenerative qualities and antimicrobial qualities. Large-scale manufacturing under Good Manufacturing Practice (GMP) conditions and the design of patient-specific scaffolds using artificial intelligence and computational modelling are critical for successful clinical translation.
Biomimetic hydroxyapatite (HAp)-based composites are promising materials for dental restorations due to their hierarchical structure and similarity to natural dental tissues. This study aims to investigate the three-dimensional crystallographic organization of HAp within nacre-inspired composites and to evaluate how different polymers infiltrations influence the structural orientation. Nacre-inspired HAp ceramic scaffolds were fabricated via bidirectional freeze-casting and subsequently infiltrated with different polymers, including Polyurethane (PU), Poly(methyl methacrylate) (PMMA), Epoxy, and Urethane dimethacrylate (UDMA). The three-dimensional structural organization and crystallite orientation of these composites were investigated using synchrotron-based 3D SAXS tensor tomography (3D SASTT), complemented by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results reveal distinct differences in crystallite alignment among the composites. HAp/PU exhibits the highest degree of preferred orientation (∼0.7-0.8), whereas HAp/PMMA and HAp/Epoxy show lower alignment values (∼0.2-0.4). The HAp/UDMA composite displays heterogeneous orientation with localized regions of moderate alignment. SEM and EDX analyses confirm variations in lamellar morphology, polymer infiltration, and porosity distribution across the composites. These findings demonstrate that 3D SASTT enables quantitative mapping of nanoscale crystallite orientation within bulk biomimetic scaffolds and provides new insights into the hierarchical structure of composites, supporting structural design of advanced dental restorative materials.
Inspired by the Bouligand helicoidal architecture of the dactyl club of the peacock mantis shrimp, this study employed direct ink writing (DIW) 3D printing to construct a three-level synergistic toughening system composed of nano-SiO2, microscale flake alumina, and a macroscale helicoidal structure. The effects of nano-SiO2 content, Bouligand helix angle, and flake alumina content on the flexural strength and fracture toughness of the composite ceramics were systematically investigated. The results showed that the optimal nano-SiO2 addition was 7 wt%, yielding a fracture toughness of 1.03 MPa·m1/2, which was 13% higher than that of pure alumina. The introduced intergranular glassy phase transformed the rigid grain-boundary bonding into a moderately strong gradient interface, resulting in higher fracture toughness for all SiO2-containing samples than for pure alumina. The Bouligand structure further increased the fracture toughness to a maximum of 1.45 MPa·m1/2 at a helix angle of 10°, representing a 39% improvement over the 0° sample. When microscale flake alumina was incorporated into the optimal matrix containing 7 wt% SiO2, the best overall mechanical performance was achieved at a flake alumina content of 5 wt%, where the flakes directly dissipated fracture energy through pull-out, fracture, and bridging mechanisms. The synergistic effect of the three structural levels was most pronounced at a helix angle of 20°, at which the sample containing 5 wt% flake alumina achieved a fracture toughness of 2.07 MPa·m1/2 with almost no loss in flexural strength, corresponding to a 113% improvement over the sample without flake alumina. These results demonstrate that three-level synergy can be achieved through nanoscale interfacial optimization, microscale energy dissipation by reinforcing phases, and macroscale crack deflection induced by the helicoidal structure, thereby providing important theoretical and experimental support for the multiscale design of high-performance bioinspired ceramic materials.
To characterize hardness and fracture toughness of ceramic CAD/CAM materials with different composition (IPS e.max CAD and MAZIC Duro) and thicknesses (1mm and 1.5mm). Blocks of CAD/CAM esthetic restorative materials (IPS e. max CAD "EC" and MAZIC Duro "MD"), forty discs were fabricated with dimensions of 10 mm × 1 mm and 10 mm × 1.5 mm. All discs were prepared using a precision cutting machine. Discs were then subjected to hardness, fracture toughness tests. Data were analyzed using independent t-tests and Two-way ANOVA (p < 0.05). For hardness test, at 1 mm and 1.5mm thicknesses, MAZIC Duro (MD) recorded a not statistically significant higher mean value of hardness (459.836 ± 20.549 HV) (468.818 ± 17.574 HV) compared to IPS e.max CAD (EC) (456.596 ± 38.102 HV) (463.346 ± 11.399 HV) (p = 0.816 and p = 0.420, respectively). For fracture toughness test, at 1 mm thickness, MAZIC Duro (MD) recorded a highly statistically significant higher mean value of fracture toughness (5.360 ± 0.133 MPa) compared to IPS e.max CAD (EC) (4.744 ± 0.151 MPa) (p < 0.001). While at 1.5 mm thickness, MAZIC Duro (MD) recorded a not statistically significant higher mean value of fracture toughness (5.291 ± .089 MPa) compared to IPS e.max CAD (EC) (5.285 ± 0.330 MPa) (p = 0.956). MAZIC Duro (MD) showed slightly higher hardness than IPS e.max CAD (EC) at both 1 mm and 1.5 mm thicknesses, but the difference was not statistically significant. For fracture toughness, MD was highly significant at 1 mm thickness, while at 1.5 mm, both materials performed similarly with no significant difference.
Simultaneously achieving sensitive lattice-distortion detection and high capacitive energy storage in dielectric ceramics is critically demanded yet challenging for fail-safe aerospace systems. Herein, a novel high-low valence co-substitution strategy is designed for a NaNbO3-based relaxor ferroelectric with the composition (1-x)[0.85(Na0.94Yb0.01Tm0.01)NbO3-0.15(Bi0.5Na0.5)TiO3]-x(Ba0.5Sr0.5)(Sn0.5Hf0.5)O3. The severe valence imbalance triggers a spontaneous Bi3+/5+ self-compensation mechanism, driving Bi migration from A- to B-site. This unique configuration induces intense lattice distortion, which substantially lowers the energy barrier for splitting Tm3+ 4f orbitals and activates a new electronic state (3F'2|3). Consequently, a direct correlation between lattice distortion and rare-earth luminescence is established, enabling real-time assessment via photoluminescence peak splitting. Concurrently, Yb3+/Tm3+ co-doping bestows anomalous thermally enhanced fluorescence for temperature sensing. Furthermore, the dual-site Bi substitution facilitates a local coexistence of polymorphic relaxor phases (rhombohedral-orthorhobic-tetragonal-cubic), yielding a high breakdown strength of 785 kV cm-1 and an outstanding recoverable energy density of 13.73 J cm-3 with 94.24% of efficiency. This work provides a paradigm for developing multifunctional materials capable of atomic-resolution operando monitoring and superior energy storage in extreme environments.
Based on the ternary phase diagram of BaO-CuO-SiO2, a series of BaCu2-xSi2O7-x (0 ≤ x ≤ 1) samples were prepared by using the conventional solid-state reaction method. By adjusting the Cu content, the phase composition between BaCu2Si2O7 and BaCuSi2O6 was effectively controlled. These two phases can coexist stably in the sintering temperature range of 1000-1060 °C. This two-phase coexistence state enhances the densification of ceramics. At x = 0.5 and sintered at 1020 °C, the sample exhibited optimal microwave dielectric properties, with a relative dielectric constant (εr) of approximately 8.07. Its Q × f (where Q is the quality factor and f is the resonant frequency) is as high as 47,200 GHz, and the resonant frequency temperature coefficient (τf) is -20.00 ppm/°C. When x = 0.5, adding 1 wt % BaCu(B2O5) (BCB) and 1 wt % LBSCA glass additives significantly reduce the sintering temperature to 890 °C. The samples still exhibit competitive microwave dielectric properties (εr ≈ 7.8, Q × f ≈ 19,900 GHz, τf ≈ -19.00 ppm/°C), along with excellent chemical compatibility with silver electrodes. These findings demonstrate that BaCu2-xSi2O7-x ceramics are promising candidates for low-temperature cofired ceramics technology (LTCC) applications.