Ceramic Network Research Articles

Constructing high performance dry-processing oxide composite electrolyte via interfacial interactions for durable solid-state lithium batteries

Composite solid electrolytes (CSEs) have considerable combination properties, which have been considered as the most promising choice for realizing advanced solid-state lithium batteries. Yet the ionic conductivity of CSEs fails to meet the practical requirements. Herein, we develop a dry-processing CSEs based on Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and succinonitrile (SN) through polytetrafluoroethylene fibrillation. On the one hand, SN can enable fast ion transport in ceramic network and serve as high-speed conducive path. On the other hand, the strong affinities of LAGP towards SN and anions can significantly improve the conductive behavior and restrict side reactions at electrolyte/Li interface. Under such regulations, the composite electrolyte exhibits high ionic conductivity (0.64 mS cm−1 at 30 °C), high transference number (0.50), and high oxidation potential (>5.0V vs. Li+/Li). The assembled lithium metal batteries demonstrate excellent stability over 300 cycles at 1.0C. This work demonstrates the ion migration mechanism and the interactions at the heterogeneous interface for SN enhanced CSEs, contributing to the development of durable solid lithium metal batteries with extended lifespan.

Titanium ion effects on the spectroscopic and electrical characteristics of germano silicate lead alumino tellurite glass ceramics for dielectric applications

The Glass-ceramics 10GeO2-(55-x) SiO2–29PbO–5Al2O3–1TeO2 doped with varying amounts of TiO2 (0 < x < 5 mol %) were prepared through the process of melt quenching followed by heat treatment. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Differential Thermal Analysis (DTA) were used to analyze these glass ceramics besides the usual spectral studies like optical absorption, Electron Paramagnetic Resonance (EPR), Fourier Transform Infrared Spectroscopy (FTIR) and Raman. These investigations demonstrated the existence of crystalline phases that comprise complexes of Ti4+ as well as Ti3+ ions that were dispersed randomly. Additionally, it is seen that Ti3+ ions, which are more prevalent as TiO2 concentration rises, take up the tetragonally deformed octahedral positions inside the network of glass ceramics. FTIR spectra of the synthesized samples provided information regarding the existence of different structural units in the glass ceramic matrix, which included SiO4, GeO4, GeO6, PbO4, PbO6, AlO6, TeO4, TeO3, TiO4, and TiO6. At 30 °C, the 3 mol % Ti-doped sample has a minimum conductivity of 1.623 × 10−9 S cm−1. Therefore, the dielectric and spectroscopic investigations suggest that glass ceramics containing 3 mol% of TiO2 are rigid and appropriate for dielectric applications.

A Comprehensive Review of Techniques for Enhancing Zirconia Bond Strength: Current Approaches and Emerging Innovations.

The increasing use of zirconia in dental restorations necessitates a comprehensive understanding of effective bonding techniques to ensure long-term clinical success. Zirconia's unique chemical composition presents challenges in achieving a durable bondas it lacks the glass phase necessary for traditional etching and silanization processes. This review evaluates current methods and emerging innovations for enhancing zirconia bond strength to resin cements. Our findings emphasize the importance of mechanical surface treatments such as air-particle abrasion and tribochemical silica-coating, which significantly improve micromechanical retention. Laser irradiation, while less commonly used, also shows promise in enhancing bond strength without compromising zirconia's structural integrity; 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primers emerged as critical agents in forming stable P-O-Zr bonds, particularly when used with resin cements containing 10-MDP. However, variations in formulation and application methods impact their overall efficacy. Resin cement demonstrated superior bond strength compared to conventional cement, but clinical outcomes varied, highlighting the importance of cement-primer compatibility and strict procedural adherence. Emerging technologies such as polymer-infiltrated ceramic networks (PICNs) and additive manufacturing (AM) of zirconia offer potential for future advancements, although they require further research to address mechanical and aesthetic challenges. In conclusion, while established methods such as sandblasting and the use of MDP primers remain reliable, ongoing research into novel materials and techniques continues to offer opportunities for enhancing zirconia bonding. Clinicians must balance effectiveness, procedural complexity, and clinical practicality when selecting the most appropriate bonding protocols for zirconia restorations.

A novel negative thermal expansion ceramic network interlayer for releasing high residual stress of Cf/SiC heterogeneous brazed joint

Negative thermal expansion (NTE) ceramics have been widely concerned in adjusting the coefficient of thermal expansion (CTE) to release the high residual stress of heterogeneous joint. However, one major problem that needs to be solved is the agglomeration problem caused by excessive ceramic particles addition. In this work, a novel NTE ceramic Sc2W3O12 network interlayer is prepared by the polyurethane template method. The Sc2W3O12 network interlayer with a single NTE phase presents a three-dimensional network structure. The NTE Sc2W3O12 ceramic is uniformly distributed in brazing seam without agglomeration with the help of unique network structure. The active Ti elements play an important role in the interface bonding, reacted with Sc2W3O12 network interlayer and Cf/SiC composites to form Cu3Ti3O and TiC/Ti5Si3 reaction layer, respectively. After introducing Sc2W3O12 network interlayer, the CTE of the composite filler is reduced from 16.6 × 10−6 K−1 to 11.9 × 10−6 K−1, a decrease of 29 %. The highest shear strength of the Cf/SiC heterogeneous joint is reached 130 MPa, which is 5.4 times than that without Sc2W3O12 network interlayer.

The Effect of Erosive Media on the Mechanical Properties of CAD/CAM Composite Materials.

This study aimed to investigate the effect of acidic media storage (gastric acid and Coca-Cola) on the mechanical properties of CAD/CAM materials. Three types of materials were tested: a polymer-infiltrated ceramic network (PICN) (Vita Enamic (En), VITA Zahnfabrik, Germany), a resin composite block (RCB) (Cerasmart (Cs), GC Corp, Japan), and a conventional resin-based composite (Gradia direct (Gr), GC Corp, Japan), which was used as a control. Beam-shaped specimens of each material, with dimensions of 16 mm × 4 mm × 1.5 mm, were prepared (90 in total). The specimens were divided into subgroups (10 each) and stored for 96 h in either gastric acid, Coca-Cola, or distilled water. Flexural strength and elastic modulus were evaluated using a three-point flexural strength test with acoustic emission (AE) monitoring. Vickers microhardness was measured before and after storage in gastric acid and Coca-Cola. Data were statistically analysed using two-way and one-way ANOVA, the Tukey's post hoc, and independent t-test at a significance level of 0.05. The results showed that Cs and En maintained their flexural strength and elastic modulus after acidic media exposure, while Gr experienced a significant decrease in flexural strength following gastric acid storage (p < 0.01). Initial crack detection was not possible using the AE system, impacting the determination of flexural strength. Exposure to acidic media decreased all materials' microhardness, with Gr showing the most notable reduction (p < 0.0001). Gastric acid had a greater impact on the microhardness of all tested materials compared to Coca-Cola (p < 0.0001). In conclusion, storage in erosive media did not notably affect the flexural strength or elastic modulus of CAD/CAM composites but it did affect hardness. CAD/CAM composite blocks demonstrated superior mechanical properties compared to the conventional composite.

Biomechanical behaviour of tilted abutment after fixed partial denture restoration of CAD/CAM materials

BackgroundFailure to restore missing teeth in time can easily lead to the mesial tilting of the distal abutment teeth. However, a fixed partial denture (FPD) can improve stress conduction and distribution and prevent periodontal injuries. In these more complex cases, it is necessary to consider various factors comprehensively to improve conventional treatment planning and achieve better results.MethodsWe selected a patient with a missing first molar and a mesial inclination of the second molar, leaving inadequate space or bone mass for implant denture restoration, necessitating an FPD for restoration. Three-dimensional finite element analysis (3D-FEA) combined with photoelastic analysis were used to explore how the inclination angle (0 ‒ 30°) and different dental restoration materials (zirconia, lithium disilicate, polymer-infiltrated ceramic network, and resin composite) affect the biomechanical behaviour of FPD‒abutments‒periodontal tissue complex.ResultsThe stress was easily concentrated in the FPD connectors, enamel shoulder collar, periapical area, and root bifurcation. The stress on FPD and the periodontal ligament (PDL) of the second premolar increased with an increase in the elastic modulus of FPD, with an opposite trend in the abutments, the alveolar bone, and the PDL of the second molar. The stress on the FPD and alveolar bone increased with increased inclination angle of the distal abutment. The stress on two abutments and their PDL were positively correlated with the inclination angle in two stages; however, when the inclination angle > 12°, the second premolar and its PDL showed a negative correlation.ConclusionsFPDs can be used for restoration within 24° of distal abutment inclination, but protecting the abutments (< 12° especially) and the periodontal tissue (> 12° especially) must be taken seriously. For this purpose, an FPD material with higher strength is recommended.

Exploring the optical behavior and relative translucency parameter of CAD-CAM resin-based composites, polymer-infiltrated ceramic network, and feldspar porcelain

ObjectivesTo evaluate and compare the optical properties and relative translucency parameter of CAD-CAM restorative materials. MethodsFour CAD-CAM materials were evaluated: Lava Ultimate (LU), Grandio Blocs (GB), VITA Enamic (VE), and VITA Mark II (VM). Disk-shaped samples in shade A2-HT were prepared (n = 10) and polished to 1.00 ± 0.01 mm of thickness. Scattering (S), absorption (K), albedo (a) coefficient, transmittance (T%), light reflectivity (RI), infinite optical thickness (X∞), and radiative transfer coefficients (μa, and μ′S) were calculated using Kubelka-Munk method and Thennadil's semi-empirical approach. Root Mean Square Error (RMSE) and Goodness of Fit (GFC) were used as performance optical behavior. Translucency differences were evaluated using the relative translucency parameter (RTP00) and 50:50 % translucency perceptibility and acceptability thresholds (TPT00 and TAT00). ResultsThe spectral distribution of S, K, T%, RI, and X∞ was wavelength-dependent. GFC and RMSE values indicated good spectral behavior matches and good comparative spectral values for RI in LU-GB, LU-VE, and GB-VE, and for K in VE-VM. VM displayed the highest scattering values across the wavelengths, while VE and VM showed lower absorption at shorter wavelengths. LU and GB had the highest transmittance. The X∞ values indicated that all 1.0 mm thick materials could be influenced by the background. No good spectral match and no good comparative spectral values were found between CAD-CAM materials and anterior bovine maxillary specimens. VM had the lowest RTP00 values with perceptible and unacceptable differences compared to CAD-CAM materials evaluated. SignificanceUnderstanding the optical behavior of different CAD-CAM materials was essential for guiding clinicians in material selection and optimizing their clinical performance. The findings confirm that the different compositions and microstructure impact the optical properties and translucency of CAD-CAM restorative materials.

Effect of resin cement viscosities and surface roughness on shear bond strength of conditioned polymer infiltrated ceramic network

BackgroundHybrid ceramics bonding with the dentinal substrate is crucial for clinical success and longevity. To enhance adhesion, the surface of ceramic restorations is modified through various conditioning techniques AimEffect of Different Surface Conditioners Erbium-doped yttrium aluminum garnet (ER: YAG) laser and Low-level laser therapy (LLLT) activated Methylene blue (MB) on the surface roughness (Ra) and shear bond strength (SBS) of Polymer infiltrating ceramic network (PICN) discs bonded using different viscosity resin cement before and after thermal aging. Material and MethodsOne hundred and fifty human central incisors and one hundred and fifty-three PICN discs were prepared. PICN discs were randomly allocated into three groups based on the surface conditioning(n = 51) Group 1:10 % HF acid-S, Group 2: LLLT (MB), and Group 3: Er: YAG laser. Following conditioning Ra scores of ten samples were performed. Surface topography of samples was performed using a scanning electron microscope (SEM). Bonding of forty PICN discs from each conditioning group was performed with high (A) or low viscosity (B) dual-curing resin cement (n = 20 each). Each subgroup was divided into two cohorts and subjected to varying storage conditions. The SBS test and failure mode analysis were performed using a universal testing machine and stereomicroscope. Descriptive statistics of SBS and Ra for each group were analyzed using ANOVA and Tukey post hoc tests. HF acid-S attained the highest Ra scores. ResultsGroup 1A (HF-S+HIGH) samples achieved the highest SBS values at baseline. Group 3A, on the other hand, displayed the lowest bond score (Er: YAG laser+HIGH) after thermal aging. Intergroup comparison analysis at baseline unveiled that Group 1A and Group 1B (HF(S) + LOW) displayed no significant difference in their bond strength scores (p>0.05). Following artificial aging, it was observed that Group 2A (LLLT (MB) + HIGH) and Group 3A (Er:YAG laser + HIGH) ) presented comparable SBS(p > 0.05). Thermal aging decreased SBS significantly in all groups. PICN conditioned with HF-S results in high surface roughness. ConclusionPICN conditioned with HF acid with silane and bonded with low-viscosity resin cement to the dentinal substrate is preferable. Aging influences SBS.

Long-Term Bonding Efficacy of CAD/CAM Hybrid Restorative Materials and Universal Adhesives.

In-office and lab milled prostheses are the staple for indirect restorations. It is therefore critical to determine their long-term bonding durability. CAD/ CAM blocks of two classes of restorative materials: 1) a nano-ceramic reinforced polymer matrix (NCPM) and, 2) a polymer-infiltrated ceramic network (PICN) were bonded using four different universal adhesives (UA) and silane systems. A lithium disilicate glassceramic (LDS) was used as a reference. The blocks were bisected and bonded with different UA/resin-cement pairs. Bonded blocks were then cut into 1.0x1.0x12.0 mm bar specimens for microtensile bond testing. Half the bars were subjected to bond strength testing immediately and the other half after aging by 50,000 thermal cycles between 5°C and 55°C. ANOVA and post-hoc tests were used to compare mean bond strength among groups. NCPM presented consistently high bond strength regardless of bonding techniques, while the bond strength of PICN and LDS were lower when bonded with UA relative to traditional silanes. The more hydrophilic UA produced higher bond strengths. Glass-ceramics exhibited lower bond strength with UA than the conventional etch-rinse-silane techniques. However, UAs preserved bonding interface in the long-term. NCPM displayed superior bond strength relative to PICN and LDS regardless of the type of adhesives and bonding techniques.

Achieving Remarkable Specific Mechanical Strength and Energy Absorption Capacity in SiC Nanowire Networks through Graded Structural Design.

Lightweight porous ceramics with a unique combination of superior mechanical strength and damage tolerance are in significant demand in many fields such as energy absorption, aerospace vehicles, and chemical engineering; however, it is difficult to meet these mechanical requirements with conventional porous ceramics. Here, we report a graded structure design strategy to fabricate porous ceramic nanowire networks that simultaneously possess excellent mechanical strength and energy absorption capacity. Our optimized graded nanowire networks show a compressive strength of up to 35.6 MPa at a low density of 540 mg·cm-3, giving rise to a high specific compressive strength of 65.7 kN·m·kg-1 and a high energy absorption capacity of 17.1 kJ·kg-1, owing to a homogeneous distribution of stress upon loading. These values are top performance compared to other porous ceramics, giving our materials significant potential in various engineering fields.

Nanoindentation creep: The impact of water and artificial saliva storage on milled and 3D-printed resin composites.

This study evaluated the effects of artificial saliva and distilled water on the nanoindentation creep of different 3D-printed and milled CAD-CAM resin composites. Disk-shaped specimens were subtractively fabricated from polymer-infiltrated ceramic network (EN) and reinforced resin composite (B) and additively from resin composite (C) and hybrid resin composite (VS) using digital light processing (DLP). Specimens from each material were divided into two groups according to their storage conditions (artificial saliva or distilled water for 3 months). Creep was analyzed by nanoindentation testing. Statistical analysis was done using two-way ANOVA, one-way ANOVA, Bonferroni post hoc tests, and independent t-test (α = 0.05). The main effects of material and storage conditions, and their interaction were statistically significant on nanoindentation (p<0.001). Storage condition had the greatest influence (partial eta squared ηP 2 =0.370), followed by the material (ηP 2 = 0.359), and the interaction (ηP 2 = 0.329). The nanoindentation creep depths after artificial saliva storage ranged from 0.34 to 0.51µm and from 0.50 to 0.87µm after distilled water storage. One of the additively manufactured groups had higher nanoindentation creep depths in both storage conditions. All specimens showed comparable performance after artificial saliva storage, but increased nanoindentation creep after distilled water storage for 3 months. The subtractive CAD-CAM blocks showed superior dimensional stability in terms of nanoindentation creep depths in both storage conditions. Additively manufactured composite resins had lower dimensional stability than one of the subtractively manufactured composites, which was demonstrated as having higher creep deformation and maximum recovery. However, after artificial saliva storage, one of the additively manufactured resins had dimensional stability similar to that of subtractively manufactured.

Do all ceramic and composite CAD-CAM materials exhibit equal bonding properties to implant Ti-base materials? An Interfacial Fracture Toughness Study

ObjectivesTo compare the interfacial fracture toughness (IFT) with or without aging, of four different classes of CAD-CAM ceramic and composite materials bonded with self-adhesive resin cement to titanium alloy characteristic of implant abutments. MethodsHigh translucent zirconia (Katana; KAT), lithium disilicate-based glass-ceramic (IPS. emax.CAD; EMX), polymer-infiltrated ceramic network material (PICN) (Vita Enamic; ENA), and dispersed filler composite (Cerasmart 270; CER) were cut into equilateral triangular prisms and bonded to titanium prisms with identical dimensions using Panavia SA Cement Universal. The surfaces were pretreated following the manufacturers’ recommendations and developed interfacial area ratio (Sdr) of the pretreated surfaces was measured. IFT was determined using the Notchless Triangular Prism test in a water bath at 36 °C before and after thermocycling (10,000 cycles) (n = 40 samples/material). ResultsIFT of the materials ranged from 0.80 ± 0.25 to 1.10 ± 0.21 MPa.m1/2 before thermocycling and from 0.71 ± 0.24 to 1.02 ± 0.25 MPa.m1/2 after thermocycling. There was a statistical difference between IFT of CER and the two top performers in each scenario: KAT and EMX before aging, and KAT and ENA after aging. Thermocycling significantly decreased IFT of EMX. The Weibull modulus of IFT was similar for all materials and remained so after thermocycling. Sdr measurements revealed that ENA (7.60)>Ti (4.97)>CER (2.85)>KAT (1.09)=EMX (0.96). SignificanceDispersed filler CAD-CAM composite showed lower performance than the other materials. Aging only affected IFT of Li-Si glass-ceramic, whereas zirconia and PICN performed equally well, probably due to their chemical bonding potential and surface roughness respectively.

Preparation, mechanical properties and anti-oxidation behavior of lightweight porosity-controlled SiC(rGO, xZrB2) composite PDCs for thermal protection

Achieving well-balanced light weight with simultaneous improvement in mechanical and antioxidant properties of SiC-based composite polymer-derived ceramics (PDCs) for hypersonic vehicle components is still a huge challenge. Herein, lightweight SiC(rGO, xZrB2) composite PDCs were prepared via re-pyrolyzing ball-milling-induced ZrB2-SiC(rGO)p/polycarbosilane-vinyltriethoxysilane-graphene (PCS-VTES-GO, PVG) blends. Main reinforcements consist of ZrB2, ZrO2(ZrC), ZrOSi and SiO2/β-SiC phases, among which favorable compatibility enables enhanced bear loading performances and high-temperature oxidation resistance. Rigid SiC(rGO)p tightly links with flexible PVG pyrolysis products, and co-assembles into robust SiOxCy/Cfree(rGO) matrix in framework owing to plentiful Si-dangling bonds at their interfaces. More interestingly, interfacial ZrOSi/ZrC transition zone can augment structural disorder of ceramic network, give bridging effects, strengthen interfacial compatibility, and even hinder further crack propagation for self-densification. Particularly, SiC(rGO, 30%ZrB2) composite PDCs possess optimal hardness (6.49 GPa) and outstanding fracture toughness (5.77 MPa⋅m1/2). Porous SiC(rGO, 30%ZrB2) composite PDCs own stable structure integrity within 60-min testing under butane torch flame at 1300 °C. Self-healing protective SiO2-ZrO2 glass layer avoids destructive structure and timely covers defects, thus retains good mechanical performances. Such good synergistic reinforcement and multiscale design of porosity-controlled composite, realizes integration of lightweight/good load-bearing characteristics with improved oxidation resistance for thermal protection system (TPS) of hypersonic vehicles.

Chemical etching of CAD-CAM glass-ceramic-based materials using fluoride solutions for bonding pretreatment.

The surface treatment of glass-ceramic-based materials, namely, lithium disilicate glass (IPS e.max CAD), feldspar porcelain (VITABLOCS Mark II), and a polymer-infiltrated ceramic network (VITA ENAMIC), using aqueous fluoride solutions and their influence on luting agent bonding were investigated. Six experimental aqueous fluoride solutions were applied to these materials, and their effects were assessed by surface topological analysis. The obtained results were compared using non-parametric statistical analyses. Ammonium hydrogen fluoride (AHF) etchant demonstrated the greatest etching effect. Subsequent experiments focused on evaluating different concentrations of the AHF etchant for the bonding pretreatment of glass-ceramic-based materials with a luting agent (PANAVIA V5). AHF, particularly at concentrations above 5 wt%, effectively roughened the surfaces of the materials and improved the bonding performance. Notably, AHF at a concentration of 30 wt% exhibited a more pronounced effect on both etching and bonding capabilities compared to hydrofluoric acid.

Comparison of fatigue lifetime of new generation CAD/CAM crown materials on zirconia and titanium abutments in implant-supported crowns: a 3D finite element analysis.

Due to the dynamic character of the stomatognathic system, fatigue life experiments simulating the cyclic loading experienced by implant-supported restorations are critical consideration. The aim of this study was to examine the effect of different crown and abutment materials on fatigue failure of single implant-supported crowns. Models were created for 10 different designs of implant-supported single crowns including two zirconia-reinforced lithium silicates (crystallized and precrystallized), monolithic lithium disilicate, polymer-infiltrated ceramic networks, and polyetheretherketone supported by zirconia and titanium abutments. A cyclic load of 179 N with a frequency of 1 Hz was applied on palatal cusp of a maxillary first premolar at a 30° angle in a buccolingual direction. In the models with titanium abutments, the polymer-infiltrated ceramic network model had a lower number of cycles to fatigue failure values in the implant (5.07), abutment (2.30), and screw (1.07) compared to others. In the models with zirconia abutments, the crystallized zirconia-reinforced lithium silicate model had a higher number of cycles to fatigue failure values in the abutment (8.52) compared to others. Depending on the fatigue criteria, polyetheretherketone implant crown could fail in less than five year while the other implant crowns exhibits an infinite life on all models. The type of abutment material had an effect on the number of cycles to fatigue failure values for implants, abutments, and screws, but had no effect on crown materials. The zirconia abutment proved longer fatigue lifetime, and should thus be considered for implant-supported single crowns.

An In Vitro Study of Retention and Marginal Adaptation of Endocrowns With Different Intracoronal Depths.

Marginal adaptation and retention of endocrowns are crucial for the success and survival of endocrowns. This study aimed to investigate the effect of different materials and intracoronal depth on the retention and marginal adaptation of CAD/CAM fabricated all-ceramic endocrowns. Thirty-six mandibular premolar teeth with an average surface area of 64.49 mm2 were prepared to receive CAM/CAM fabricated endocrowns. Samples were divided randomly and equally into groups of lithium disilicate with 2 mm intracoronal depth (LD2), lithium disilicate with 4 mm intracoronal depth (LD4), polymer infiltrated ceramic network with 2 mm intracoronal depth (PICN2) and polymer infiltrated ceramic network with 4 mm intracoronal depth (PICN4). All endocrowns were cemented using ParaCore resin cement with 14N pressure and cured for 20 seconds. Fifty measurements of absolute marginal discrepancy (AMD) were done using a stereomicroscope after cementation. After 24 hours, all samples were subjected to thermocycling before the retention test. This involved using a universal testing machine with a crosshead speed of 0.5 mm/min and applying a load of 500N. The maximum force to detach the crown was recorded in newtons and the mode of failure was identified. Two-way ANOVA revealed that the AMD for PICN was statistically significantly better than lithium disilicate (p=0.01). No statistically significant difference was detected in the AMD between the two intracoronal depths (p=0.72). PICN and endocrowns with 4 mm intracoronal depth had statistically significant better retention (p<0.05). 72.22% of the sample suffered from cohesive failures and 10 LD endocrowns suffered adhesive failures. Within the limitations of this study, we found that different materials and intracoronal depths can indeed influence the retention of CAD/CAM fabricated endocrowns. Based on the controlled setting findings, PICN was found to have better retention and better marginal adaptation than similar lithium disilicate premolar endocrowns.

Graphite-assisted structural design of hierarchically porous SiC(rGO) PDCs with excellent capacity in thermal protection/insulation and load bearing for hypersonic vehicles

High flight speed of hypersonic vehicles will push thermal insulation composites to achieve balanced enhancement of high porosity with increasing load-bearing capability. Herein, hierarchically porous SiC(rGO) polymer-derived ceramics (PDCs) with lightweight, heat-insulating, anti-ablative and tough engineered merits, are designed from polycarbosilane-vinyltriethoxysilane-graphene oxide precursors by re-pyrolysis/graphite-assisted decarburization. Graphite pore-forming agents tightly coupled with SiOxCy/Cfree(rGO) by C-dangling bonds, can inhibit SiOxCy decomposition, increase ceramic network disorder and expedite concurrent removal of Cfree. SiO2 generated from Si-dangling oxidation bonding, efficiently densifies framework to retain mechanical performances, and meanwhile creates more interfaces to enhance phonon scattering. Such structure similar to nodular cast iron confers low thermal conductivity (0.11 W·m-1·K-1), particularly, fully preserves good compressive strength (5.4 MPa) for SiC(rGO)40%. Under both cyclic butane flame ablation (∼1300 °C) and long-term oxidation for 7200 s, self-healing effect of SiO2 imbues products with good structural integrity, shedding light on the opportunity to apply any thermal protection system.

Fracture resistance of additively or subtractively manufactured resin-based definitive crowns: Effect of restorative material, resin cement, and cyclic loading

ObjectiveTo evaluate how restorative material, resin cement, and cyclic loading affect the fracture resistance of resin-based crowns fabricated by using additive or subtractive manufacturing. MethodsA right first molar crown standard tessellation language (STL) file was used to fabricate 120 crowns from one subtractively manufactured polymer-infiltrated ceramic network (SM) and two additively manufactured resin composites (AM-B and AM-S) (N = 40). These crowns were randomly divided into 4 groups within each material according to the dual-polymerizing resin cement to be used (RX and PN) and the aging condition (n = 10). After cementation, the crowns without cyclic loading were subjected to fracture testing, while the others were first cyclically loaded (1.7 Hz, 1.2 million cycles, and 49-N load) and then subjected to fracture testing. Data were analyzed with generalized linear model analysis (α = .05). ResultsFracture resistance of the crowns was affected by material, resin cement, and cyclic loading (P ≤ .030). However, none of the interactions significantly affected fracture resistance of tested crowns (P ≥ .140). Among tested materials, SM had the highest fracture resistance, whereas AM-B had the lowest (P ≤ .025). RX led to higher fracture resistance, and cyclic loading decreased the fracture resistance (P ≤ .026). SignificanceTested materials can be considered reliable in terms of fracture resistance in short- or mid-term (5 years of intraoral simulation) when used for single molar crowns with 2 mm occlusal thickness. In the long term, polymer-infiltrated ceramic network crowns cemented with RelyX Universal may provide promising results and be less prone to complications considering higher fracture resistance values obtained.

Intraoral wear of PICN CAD-CAM composite restorations used in severe tooth wear treatment: 5-year results of a prospective clinical study using 3D profilometry

ObjectivesTo evaluate, in a prospective clinical study over 5 years with ex vivo 3D profilometry analyses, the intraoral wear of Polymer-Infiltrated Ceramic Network (PICN) CAD-CAM composite restorations used in severe tooth wear treatment with the One-Step No-Prep technique. Methods192 PICN (Vita Enamic) restorations on molars and premolars were included in a prospective clinical study involving patients treated according to the One-step No-prep protocol (n = 7). All patients showed clinical signs of bruxism. Replicas of restorations on molars and premolars were realized at each evaluation time (baseline and then every year up to 5 years) and scanned to perform 3D profilometry. Baseline and recall scans were superimposed with Geomagic Control software. The mean material wear was calculated for the full occlusal area (FOA) and for the occlusal contact area (OCA), respectively. Clinical evaluation of restorations was performed at recall. ResultsAt 5 years, the estimated mean material wear for FOA was inferior to the accuracy threshold of the profilometry measurement chain. For OCA, the estimated mean wear of the material was – 27.97 µm. This material wear was shown to be significantly influenced by time (p < 0.0001) and patient (p = 0.026), while the type of tooth (molar or premolar) had no influence. At 5 years, the survival and the success rates of restorations were 99.48% and 90.62%, respectively. SignificanceThe PICN material exhibits a low wear process in the treatment of severe tooth wear despite the presence of clinical signs of bruxism, and it constitutes a suitable material for the One-step No-prep technique.

3D-Networks Based Polymer Composites for Multifunctional Thermal Management and Electromagnetic Protection: A Mini Review

3D-Networks Based Polymer Composites for Multifunctional Thermal Management and Electromagnetic Protection: A Mini Review