High-power applications demand piezoceramics that combine large piezoelectric strain coefficients d33 and low mechanical loss (high Qm). In this study, [001]-textured Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 (PMN-PZT) ceramics are fabricated using BaTiO3 seeds to induce grain orientation and manganese doping for hardening. Notably, by leveraging the rapid oxygen transport mechanism within the perovskite lattice, ceramics sintered in an oxygen atmosphere achieves a high relative density of 98%-99%, significantly exceeding the 95.6% achieved in air. The dense textured ceramics exhibit excellent combined soft and hard properties, showing high d33 of 1025 pC/N and high Qm of 810. Their performance under high drive is further evaluated via electrical transient response method. The results indicate that even at a high vibration velocity of 1.0 m/s, the dense ceramics maintained a high Qm of 560, higher than that of the less-dense textured counterparts (Qm = 140). Moreover, reduced strain hysteresis suggests that the dense microstructure enhances domain wall pinning, thereby mitigating mechanical losses due to inhomogeneous strain under high fields. In summary, this work demonstrates that oxygen-atmosphere sintering effectively improves both mechanical and electrical properties in textured ceramics, showing great promise for high-power piezoelectric applications.
The present study synthesizes cerium (Ce)/yttrium (Y) co-doped zirconia ceramic powder by the sol-gel method, with the effect of a two-step sintering protocol on the microstructure, phase type, physical and mechanical properties, and resistant hydrothermal aging of zirconia ceramics with different Ce and Y dopant concentrations. The ceramic samples were prepared by means of spark plasma sintering (SPS) and post-sintering (P) using Ce/Y co-doped zirconia powder. The surface morphology and element distribution of the samples were characterized by scanning electron microscope (SEM) coupled with energy dispersive spectrometer (EDS); With the help of ImageJ software, the grain size distribution was extracted from SEM images. X-ray diffraction (XRD) analysis was performed to examine the phase composition of the prepared powders and ceramic samples before and after hydrothermal aging. Furthermore, the relative density, Vickers hardness and fracture toughness of the ceramic samples were systematically measured. The results indicated that the grain size of Ce/Y co-doped zirconia powder diminished with increasing doping concentration, reaching a minimum of 31.07 nm. This trend was mirrored in the ceramic samples fabricated via SPS or SPS-P, with their grain size variation aligning with that of the powder. Notably, the SPS ceramics achieved a relative density of 5.75 g/cm3, a Vickers hardness of 10.29 GPa and a fracture toughness of 6.42 MPa·m1/2. In contrast, the SPS-P ceramics attained a relative density of 6.22 g/cm3, a Vickers hardness of 10.34 GPa and a fracture toughness of 6.55 MPa·m1/2. Furthermore, hydrothermal aging treatment results highlighted the ceramics prepared by SPS exhibited superior resistance to hydrothermal aging compared to those prepared by SPS-P. In this study, Ce/Y co-doped zirconia powders and ceramics were prepared, and the influence law of doping concentration on their microstructure and macroscopic properties was systematically analyzed, and new ideas were provided to enhance the material properties.
High-energy-density ceramic capacitors that do not rely on lead critical for mitigating environmental pollution and addressing the growing energy demand. However, electromechanical coupling often prevents the simultaneous enhancement of maximum polarization (Pmax) and breakdown field strength (Eb), which limits further advances in energy storage performance (ESP). To overcome this constraint, we adopt a macroscopic structural design strategy and fabricate sandwich-structured ceramics using a tape-casting process. This architecture enables concurrent regulation of polarization and breakdown strength, effectively alleviating their intrinsic trade-off and substantially increasing the energy density. Consequently, lead-free ceramics with a sandwich configuration deliver a recoverable energy density (Wrec) of 6.83 J·cm-3 accompanied by a high efficiency (η) of 92.0% under 487 kV·cm-1. The η remains above 93.3% over frequencies from 1 to 100 Hz and temperatures from 20°C to 140°C, while the variation in Wrec stays within ±5.2%. In addition, the ceramics exhibit a high power density (PD) of 78.52 MW·cm-3. These results highlight sandwich-structured lead-free ceramics as promising candidates for high-performance energy-storage capacitors.
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.
Molybdenum disilicide ceramics have become highly promising high-temperature structural materials due to their high melting point and excellent high-temperature oxidation resistance, but their room-temperature brittleness limits their broader application. Therefore, this study aims to improve the physical and mechanical properties of MoSi2 by incorporating reinforcing phases and employing high-temperature and high-pressure sintering methods. High-density MoSi2-20 mol % Mo5Si3 composite ceramic samples were prepared by a sintering process at a constant pressure of 4.5 GPa over the temperature range of 1100-1300 °C. Characterization results showed that the composite ceramic samples exhibited high relative density. Its maximum measured values of Vickers hardness and fracture toughness are 15.358 ± 0.187 GPa and 6.497 ± 0.424 MPa·m1/2, respectively, both superior to most molybdenum silicide-based materials prepared by conventional methods. It also possesses excellent heat/electrical transfer performance. Notably, the sintered samples showed no significant mass gain in an air atmosphere at 1500 °C, exhibiting excellent high-temperature oxidation resistance. The underlying mechanism is revealed by ab initio molecular dynamics simulations. This study provides a new route for preparing high-performance molybdenum silicide-based composite ceramics and lays a theoretical and experimental foundation for their application in extreme environments, such as hot-section components in aerospace engines and missile nozzles.
Electrolytic manganese residue (EMR) has caused severe pollution due to its high concentration of water-soluble contaminants, posing a major obstacle to the sustainable development. To address the low utilization of EMR and its associated pollution, mullite-enhanced anorthite ceramics were successfully prepared at temperatures below 1200 °C by using EMR and calcined kaolin (CK). Different EMR/CK ratios, sintering temperatures, and holding times were investigated. The optimal bending strength of 65.09 MPa was obtained at 1160 °C for 60 min with EMR/CK ratio of 1:1. The enhanced mechanical strength originates from the altered crack propagation path caused by in-situ synthesis of mullite microcrystals. Phase composition, microstructure, and thermal analysis revealed that CaO reacts with α-SiO2 to form wollastonite and gehlenite, ultimately synthesizing anorthite above 1100 °C. The spinel-like intermediate during the mullite formation provides most of aluminum source and part of silicon source for anorthite synthesis. This study offers a sustainable solution for solid waste co-disposal and heavy metal pollution control.
During the high-temperature deposition of tungsten thin films on alumina ceramic substrates, the inherent mismatch in thermal expansion coefficients frequently triggers interfacial delamination, where uncontrollable factors in stochastic surface topographies can exacerbate localized stress concentrations. To resolve these interfacial failures, the enhancement of interfacial adhesion through a deterministic surface microgroove design is identified as the general objective of the present research. Within this framework, the establishment of a robust quantitative mapping between the transverse scratching offset distances and the resultant periodic microgeometry is first pursued as a specific experimental objective. This methodological approach effectively transforms the stochastic nature of the substrate into deterministic geometric configurations. Second, a specific numerical objective is fulfilled by evaluating the interfacial stress redistribution and damage evolution utilizing refined thermomechanical coupled simulations based on the cohesive zone model. The integrated findings demonstrate that optimizing the microgroove spacing effectively governs the morphological transition and broadens stress diffusion pathways to mitigate thermal mismatch effects. Specifically, the structural optimization at a spacing of 28.8 µm facilitates an approximately 31.8% reduction in the maximum interfacial stress and a 10% decrease in the average film stress compared to the 13.6 µm spacing. Finally, this research clarifies the underlying mechanisms of stress buffering and provides a rigorous engineering methodology for the structural design of reliable high-performance ceramic-metal interfaces in extreme environments.
Large-scale reuse of copper tailings can mitigate environmental hazards and recover strategic elements; this work investigates the feasibility of producing foam glass-ceramics with high copper-tailing content (>70 wt%) by tuning the CaO/SiO2 ratio to couple melt viscosity and crystallisation. The comprehensive utilisation of these tailings helps mitigate environmental pollution and enhance resource efficiency. In this study, foam glass-ceramics with varying CaO/SiO2 ratios were synthesised through melt quenching followed by foaming heat treatment. The effects of different CaO/SiO2 ratios on the foaming behaviour, crystallisation, and microstructure were investigated using DSC, FTIR, viscosity, XRD, SEM, and CT. The results indicate that increasing the CaO/SiO2 ratio disrupts the three-dimensional network structure of the glass, which lowers the glass viscosity and influences the bubble size and distribution in the foam glass-ceramics. Additionally, the increased CaO content promotes crystal precipitation and enhances the compressive strength of the foam glass-ceramics. At a CaO/SiO2 mass ratio of 0.22, the foam glass-ceramics exhibited the lower bulk density (240 kg/m3) and thermal conductivity (0.07 W/m·K). The materials also demonstrated good water absorption and compressive strength. This study highlights the potential of using copper tailings in foam glass-ceramics to improve their overall performance, offering promising energy-saving and environmentally friendly solutions.
The demand for rapid, reliable, and esthetic ceramic restorations continues to drive innovation in dental materials and chairside manufacturing technology. However, conventional yttria-stabilized zirconia presents an inherent trade-off between mechanical and optical properties, with moderate fracture toughness ≤5 MPa·m1/2. This study investigates the feasibility of chairside speed-sintering of a 4.5 mol% CaO-stabilized tetragonal zirconia polycrystal (4.5Ca-TZP), focusing on its microstructure, mechanical reliability, translucency, and aging resistance. Nano-sized 4.5Ca-TZP powders were compacted and speed-sintered within 60 min at 1,250 °C to 1,350 °C. Four sintering groups were evaluated (n = 20/group for density; n = 1 for grain size; n = 10 for hardness; n = 3 for Rietveld refinement; n = 5 for fracture toughness, translucency, and aging; n = 30 for biaxial strength and Weibull analysis) with statistical differences set at α = 0.05. Speed-sintering gave rise to fully dense ceramics (≥99% relative density) with a homogeneous, fine microstructure (<200 nm) and negligible monoclinic content (≤2 vol%). The ceramics demonstrated excellent mechanical reliability, exhibiting a characteristic strength of ≥1.1 GPa and a Weibull modulus ≥11. Hardness slightly decreased with increasing temperature, whereas translucency reached its maximum (≈22) at 1,250 °C. Indentation testing revealed the absence of radial cracks in specimens sintered above 1,300 °C. No tetragonal-to-monoclinic transformation occurred after 20 h of hydrothermal aging at 134 °C, demonstrating aging resistance. Compared with conventionally sintered 4.5Ca-TZP, speed-sintered ceramics showed comparable translucency and strength with enhanced mechanical reliability but significantly lower fracture toughness of >5 MPa·m1/2. Overall, this work demonstrates that 4.5Ca-TZP can be speed-sintered to achieve fully dense zirconia with performance exceeding that of conventional 3Y-TZP, providing a tougher alternative zirconia restoration. A computer-aided design/computer-aided manufacturing-milled crown fabricated as a proof of concept showed isotropic shrinkage, supporting its potential for chairside application, while further investigation of long-term resistance, large-scale manufacturing, and dimension limitations is required to confirm clinical applicability.
The continuous drive for higher efficiency in gas turbines has led to increased combustion temperatures, making the thermal shock resistance of thermal insulation tiles a critical factor limiting performance. Corundum-mullite multiphase ceramics are widely used in such applications; however, their performance is often constrained by an inherent trade-off between mechanical strength and thermal shock resistance. In this work, a synergistic modification strategy based on rare-earth disilicate phases was developed, wherein Y2O3 and SiC were incorporated into a corundum-mullite matrix to enable in situ formation and controlled distribution of Y2Si2O7 via gel casting. During sintering, Y2Si2O7 acts as a transient liquid phase, facilitating densification and grain boundary strengthening; upon thermal shock, it migrates to fill and heal grain boundaries and microcracks, thereby significantly enhancing thermal shock resistance. The optimized sample S5, sintered at 1400 °C, exhibited a bulk density of 2.12 g/cm3 and a bending strength of 68.43 MPa. Notably, after 30 thermal shock cycles (air cooling from 1000 °C to RT), its bending strength increased to 79.71 MPa, corresponding to a 16.48% enhancement. This work provides an effective strategy for incorporating rare-earth disilicates into multiphase ceramics and offers valuable guidance for the development of high-performance components for gas turbines.
Ultrasonic motors have attracted considerable attention in precision actuation applications because of their advantages over conventional electromagnetic motors, such as compact structure, high positioning accuracy, immunity to electromagnetic interference, noise-free operation, and suitability for low-temperature environments. However, conventional traveling-wave linear ultrasonic motors usually rely on boundary constraints to establish stable traveling waves, which may limit their structural flexibility and self-propelled capability. To address this issue, this paper proposes a free-boundary traveling-wave linear ultrasonic motor capable of realizing self-propelled motion. The motor features a projection structure at each end of the stator. Two piezoelectric ceramics are placed at one end for excitation, while a damping material is arranged at the other end for energy absorption. This design enables the motor to generate traveling waves without requiring fixed boundary conditions. The motor operates in the B(3,1) out-of-plane vibration mode to enhance the energy absorption capacity of the non-excited end and reduce its standing wave ratio (SWR). A finite element model of the motor is established to investigate its vibration characteristics. In addition, a novel method for estimating the standing wave ratio is proposed by using piezoelectric ceramics attached to the motor surface, replacing the traditional calculation approach. A prototype is fabricated to verify the feasibility of the proposed design. Experimental results show that the prototype achieves a minimum SWR of 1.81, a no-load speed of 42.1 mm/s, and a maximum output force of 0.465 N. These results confirm the feasibility of the proposed scheme and provide a new approach for the design of free-boundary traveling-wave linear ultrasonic motors.
Periodontal debridement using ultrasonic instruments and air polishing is a standard procedure in clinical dental practice. While effective in managing periodontal health, these techniques can compromise the integrity of dental restorations. This article reviews laboratory evidence on the effects of ultrasonic instrumentation and air polishing on various restorative biomaterials, focusing on surface roughness and marginal integrity. Findings indicate that high-strength ceramics such as zirconia and lithium disilicate are more resistant to damage than feldspathic ceramics, resin-modified glass-ionomer cements, and resin-based materials, which are more susceptible to damage. The use of low-abrasive powders such as erythritol and glycine is recommended to mitigate adverse effects. Actionable recommendations are provided to inform favorable maintenance protocols for restorations during periodontal therapy.
This paper proposes an ultrasonic motor capable of achieving both single-mode and multi-mode coupled operation. The stator structure is simple and fully symmetrical, consisting of two parallel sandwich-type vibrators. The motor achieves flexible switching between single-mode and multi-mode coupled operation by selectively exciting the longitudinal vibration modes of the left and right vibrators. Due to the symmetry of the dual-vibrator stator structure, the frequencies of the two coupled modes are naturally close, and improving motor design efficiency. Moreover, this dual-vibrator structure enables the motor to maintain consistent bidirectional output characteristics even when operating in single-mode configuration. Since piezoelectric ceramics operate in the d33 mode with high electromechanical coupling capability, the sandwich structure effectively enhances the output performance of the motor. This thesis first details structure and operating principles of the motor. Subsequently, finite element analysis software is employed to conduct modal analysis, frequency and transient analysis of the stator, validating its feasibility. Finally, a prototype is fabricated and tested on an experimental platform to evaluate its output performance. In single-mode operation, the prototype achieves a maximum speed of 434 mm/s, a maximum load of 0.8 kg, and a maximum efficiency of 5.03 %. In multi-mode coupled drive mode, it achieves a maximum speed of 612 mm/s, a maximum load of 1 kg, and a maximum efficiency of 3.69 %. The motor also achieves a resolution as high as 8.1 nm. The motor features a compact structure and simple drive mechanism, enabling seamless switching between two operating modes. It exhibits relatively favorable output characteristics, making it suitable for various precision drive applications such as optical instruments, medical equipment, and aerospace systems.
Multilayer zirconias have recently been introduced as dental biomaterials to combine improved translucency with sufficient mechanical reliability by implementing yttria-driven gradients in phase composition. Such materials can be considered functionally graded ceramics, where local phase stabilization influences strength and crack resistance. However, manufacturer-specific gradient profiles and their structure-property relationships remain insufficiently characterized. This study investigated two commercially available multilayer zirconias with distinct gradient concepts: IPS e.max® ZirCAD Prime (continuous gradient) and KATANA™ Zirconia YML (stepwise gradient). Ten equidistant sections along the blank height were analyzed using quantitative X-ray diffraction and Rietveld refinement to quantify zirconia phase fractions and estimate local Y2O3 content. Mechanical behavior was evaluated by biaxial flexural strength testing (ball-on-three-balls method) and fracture toughness testing using the chevron-notched beam technique. Both materials exhibited pronounced yttria- and phase-dependent gradients consistent with their reported layer designs. Regions with increased yttria content showed higher t″ fractions and reduced fracture toughness and strength, whereas deeper regions displayed increased mechanical performance associated with higher fractions of transformable tetragonal phase. These findings emphasize that multilayer zirconias exhibit spatially dependent mechanical properties, which should be considered in biomaterial selection and restoration design, particularly when balancing aesthetic demands and fracture resistance.
Two-dimensional hexagonal boron nitride (hBN) is attractive for several emerging applications. Ion bombardment can be used to modify the hBN properties. However, the understanding of radiation damage buildup in hBN remains limited. Here, we investigate the effects of the dose rate and ion mass on radiation damage buildup by studying 40 nm-thick hBN films bombarded at room temperature with 500 keV 4He, 15N, 40Ar, and 129Xe ions and comparing with results for ion bombardment of polycrystalline hBN ceramics. Raman spectroscopy is used to quantify damage buildup, and transmission electron microscopy is used for microstructural analysis. Experiments are complemented by molecular dynamics simulations of the formation and evolution of point defects. Lighter ions are found to be more efficient at disordering hBN than heavier ions. This observation points to a critical role of intracascade defect processes. In contrast, a negligible dose rate effect observed suggests limited intercascade defect dynamic annealing processes for these irradiation conditions. These findings provide a fundamental basis for hBN defect engineering.
To evaluate the long-term clinical performance of bilaminar restorations-functional palatal resin-based composite (RBC) veneers (PVs) combined with labial ceramic veneers (LVs) - used for the rehabilitation of localized anterior tooth wear with the Dahl concept, with emphasis on survival, failure patterns, and material- and patient-related risk factors. Twenty-six patients (156 maxillary anterior teeth) received bilaminar restorations. PVs were fabricated from RBCs (Enamel Plus HRi BioFunction or Estelite Sigma Quick), and LVs from lithium disilicate ceramics (IPS e.max Press or GC Initial LiSi Press). Clinical evaluation was performed at 3-5 and 6-8 years using USPHS criteria. Outcomes were classified as success, survival with deficiencies, or failure requiring replacement. Survival was analyzed using Kaplan-Meier estimates, and risk factors were assessed by multivariable regression analysis (p < 0.05). Cumulative survival was 92.3% for PVs and 98.1% for LVs. Fifteen restorations (4.8%) required replacement, predominantly PVs due to wear- and fatigue-related deterioration. No survival difference was observed between LVs. PV performance showed significant material-related differences, with Estelite Sigma Quick exhibiting fewer failures and higher success rates than Enamel Plus HRi BioFunction. Unsatisfactory oral hygiene, bruxism, coffee/tea consumption, and increasing restoration age were associated with higher failure risk. Baseline erosion severity significantly affected PVs, but not LVs outcomes. Bilaminar restorations combined with the Dahl concept offer a durable, minimally invasive solution for localized anterior tooth wear over up to eight years. However, while LVs demonstrate excellent long-term stability, the performance of functional PVs remains material-dependent and requires ongoing maintenance.
Titanium-extracted tailing is a by-product generated during titanium-bearing blast furnace slag treatment process. The crystallization behavior of the titanium-extracted tailing during the cooling process is significant to its utilization for glass ceramics preparation. In this work, the CaO-SiO2-Al2O3-MgO-TiO2-FeO slag was used to explore the effect of CaO/SiO2 ratios on titanium-extracted tailing crystallization. FactSage 8.2 calculation and mineralogical characterizations were conducted to investigate the phase and microstructure evolution during the slag cooling process. Single hot thermocouple technique (SHTT) was employed for in situ observation of the crystallization process of the slag during the cooling process. The obtained results indicated that the perovskite, melilite, spinel, diopside and anorthite phases would be crystallized during the cooling process when the CaO/SiO2 ratios of the slag were 0.7-1.1. Increasing the CaO/SiO2 ratio to 1.3 and 1.5 promoted the crystallization of olivine and merwinite phases, however, inhibited the crystallization of diopside and anorthite phases. The initial crystallization temperature and the liquid phase disappeared temperature of the slag enhanced with improving CaO/SiO2 ratios. The initial crystallization temperature was controlled by perovskite phase precipitation when the CaO/SiO2 ratios of slag reached 0.7-1.3. Whereas the initial crystallization temperature was controlled by the crystallization of spinel phase when the CaO/SiO2 ratio of slag was 1.5. The incubation time for crystal nucleation reduced with increasing CaO/SiO2 ratios that promoted slag crystallization. Moreover, increasing the CaO/SiO2 ratio from 0.7 to 1.5 enhanced the critical cooling rate from 4 °C s-1 to 11 °C s-1.
Electrical stimulation that mimics endogenous electric fields represents a promising therapeutic strategy for wound healing. In this study, a lead-free piezoelectric composite film was fabricated by incorporating (K,Na)NbO3(KNN) ceramics into a polyvinylidene fluoride (PVDF) matrix via tape casting. The introduction of KNN fillers significantly enhanced the β-phase content and piezoelectric output of PVDF. Under ultrasound irradiation, the resulting KNN/PVDF film effectively promoted fibroblast proliferation and migration in vitro, achieving a 54.84% migration rate within 24 h and upregulating key wound-repair genes, including TGF-β and VEGF. In vivo, the composite film markedly accelerated the healing of full-thickness skin defects in rats, promoted neovascularization, and achieved approximately 95% wound closure by day 9. These results demonstrate that the KNN/PVDF composite film provides an effective wireless platform for biomimetic electrical stimulation in tissue regeneration.
Monolithic zirconia has become increasingly popular in clinical dentistry as an indirect restorative material fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. It is widely used due to its favorable combination of mechanical strength, aesthetic potential, and biocompatibility. Its monolithic design reduces the risk of veneer chipping, thereby improving restoration longevity. To narratively review the mechanical and adhesive properties of monolithic zirconia and discuss their clinical implications. This narrative review was based on a comprehensive, non-systematic literature search conducted using PubMed/MEDLINE, Scopus, and Web of Science. English-language publications addressing monolithic zirconia, mechanical behavior, surface treatments, adhesive strategies, and clinical performance were considered. Additional studies were identified through manual screening of reference lists. Study selection was guided by relevance to the review topic rather than predefined inclusion or exclusion criteria. Monolithic zirconia demonstrates high flexural strength and fracture toughness, supporting its use in posterior load-bearing restorations. However, direct exposure to the oral environment may promote low-temperature degradation (LTD), potentially affecting long-term mechanical stability. Despite improvements in translucency, aesthetic performance remains a consideration. Adhesive durability depends largely on appropriate surface conditioning and the use of functional primers, particularly those containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP), which enhance chemical bonding to zirconia. Monolithic zirconia offers a reliable balance between strength and clinical durability. Nevertheless, its long-term performance is influenced by environmental exposure and adhesive protocols. Further research is needed to optimize the resin-zirconia interface while maintaining both mechanical reliability and aesthetic outcomes.
Bone resorption progresses in the alveolar ridge after tooth loss. In extremely athropic maxillae, treatment options include quad-zygoma implants, iliac bone augmentation with intraosseous implants, (the All-on-4 concept), Group-SUB periosteal implant. In this study, extremely atrophic maxilla was defined as an edentulous ridge with 3 mm crest thickness, 6 mm nasal base-crest distance, and 5 mm sinus floor-crest distance. This study aimed to compare stress distribution of these protocols using finite element analysis. In this study, analyses were performed using the finite element method A total of three groups were included in the finite element analysis, each representing a different treatment configuration applied to an extremely atrophic maxilla. The AOF (All-on-4) configuration consisted of four conventional implants placed in the canine and first molar regions following iliac bone augmentation, supporting a metal-ceramic prosthetic restoration. The ZYG (Zygomatic) configuration consisted of four extra-maxillary zygomatic implants (quad zygoma), with two implants placed in the canine region and two in the posterior region on each half of the maxilla, supporting a metal-ceramic prosthetic restoration. The SUB (Subperiosteal) configuration consisted of a subperiosteal implant framework supporting a metal-ceramic prosthetic restoration. For all three configurations, three-dimensional finite element models were generated based on standardized geometric reconstruction of an extremely atrophic maxilla. Implant positioning, prosthetic design, material properties, boundary conditions, and loading scenarios were defined according to previously published finite element modeling protocols, and identical modeling assumptions were applied to all groups to allow direct comparison. In this study, vertical occlusal force of 150 N and an oblique force of 50 N at a 30° angle were applied. In the models created, minimum stresses in the cortical bone and minimum and maximum principal stresses (P max) in the spongiose bone were observed. The Von Mises Stress values of the implants and abutments were analyzed. Stress in the alveolar bone remained within the physiological limits of the bone. However, it was determined that Group-SUB created less stress on the alveolar bone than the other Groups. When the Von Mises Stress values on the implants and abutments were examined, it was determined that Group-AOF had the highest Von Mises Stress values, followed by Group-ZYG (and Group 3-SUB had the lowest Von Mises Stress values. When the stresses occurring in the prosthetic restoration were evaluated, similar results were observed. Our data suggest that zygoma implants may reduce stress concentration in extremely atrophic maxillae; however, clinical validation is required.