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The introduction of glass matrix ceramics in dental restorations has revolutionized dental aesthetics. A key challenge in the development of dental glass ceramics is achieving nanocrystalline glass ceramics with superior mechanical properties without compromising translucency. In this study, ZrO2-SiO2 glass ceramics doped with amorphous Al2O3 were investigated to address these requirements. The results indicate that the segregation of Al3+ at the grain boundaries of ZrO2 crystallites and the nano-domains of amorphous Al2O3 significantly influences the microstructure, including the grain size and stabilization of tetragonal ZrO2, as well as the translucency and mechanical properties. The composition with 10 mol% Al2O3 exhibits the highest toughness of 8.05 MPa center dot m1/2 while maintaining excellent translucency. Moreover, the composition with 5 mol% Al2O3 demonstrates lower translucency but achieves a high flexural strength of 960 MPa. Overall, the mechanical properties of these translucent glass matrix ceramics surpass those of commercially available dental glass ceramics, highlighting their potential for dental restoration applications.

Periodontal disease caused by bacterial accumulation is a critical issue affecting the longevity of related materials and implants. Enhancing the antibacterial properties of glass ceramics remains a significant challenge. Due to their excellent mechanical properties, ZrO2-SiO2 glass ceramics have shown great potential in dental restoration. Here, to endow ZrO2-SiO2 glass ceramics with antibacterial properties, nitrogen ion implantation was performed to modify their surfaces. The effects of nitrogen fluence on the microstructural, mechanical and antibacterial properties were investigated. The results showed that phase transformation from tetragonal to monoclinic phase occurred after ion implantation. Surface hardening was observed in the sample under the low fluence ion implantation. Partial amorphization and blistering were observed at the highest fluence of 6.0  1017 ions/cm2. XPS analysis revealed that the implanted nitrogen ions mainly form O-Zr-N, N-Si-O and Si-N bonds. Staphylococcus aureus testing showed that the antibacterial properties of ZrO2-SiO2 glass ceramics can be enhanced after implantation, which may be attributed to the formation of reactive nitrogen species. The results show that nitrogen implantation can enhance the antibacterial properties of ZrO2-SiO2 glass ceramics without compromising their mechanical properties.

Review articles are critical to the scientific enterprise. They are often the starting point for researchers exploring a new area or those searching for a quick overview of the field. Good reviews serve as references for years to come and can be crucial teaching tools. Review articles typically receive more citations and more views than research articles and can elevate the impact of the research articles cited within. Yet, many authors struggle with writing reviews. As editors of the Journal of Materials Chemistry B, we prepared this article to assist authors in crafting impactful reviews. Although our focus is JMCB, these thoughts should be broadly translatable to other journals.

Zircon (ZrSiO4) ceramics have been widely used in many fields due to their excellent physical and chemical properties. However, ZrSiO4 ceramics typically possess moderately low mechanical properties, which hinders their wider application. Meanwhile, elevated temperatures (similar to 1500 degrees C) are required to obtain high-purity synthetic ZrSiO4 ceramics, which is time- and energy-consuming. In the present study, we prepared mechanically robust ZrSiO4 ceramics at low temperature (similar to 1170 degrees C) with a low doping level of Mn dopant (<2 mol%). The ZrSiO4 ceramic processed by hot isostatic pressing with .5 mol% Mn dopant achieved the highest flexural strength (512 MPa), elastic modulus (341 GPa), and nanohardness (20.8 GPa). These values are significantly higher than conventional ZrSiO4 ceramics. The strengthening mechanisms of the prepared ZrSiO4 ceramics were attributed to the formation of homogeneously-distributed nanopores due to incomplete densification and submicron ZrSiO4 grains (similar to 300 nm). The nanopores avoided stress concentration and deflected microcracks during loading, and the submicron ZrSiO4 grains endowed the ZrSiO4 ceramics with grain refinement strengthening. The results reported in this study would offer guidance to fabricate mechanically robust ZrSiO4 ceramics at low temperatures with a low doping level of dopant.

Study Design: Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study.Objective.The effect of monetite synthetic bone graft (SBG) containing calcium pyrophosphate and beta-tricalcium phosphate on cervical spinal fusion in a noninstrumented two-level large animal model.

Summary of Background Data: ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in similar to 2.6% of the surgeries. SBG may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based SBGs for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion.

Materials and Methods: Four adult female Danish G & ouml;ttingen minipigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG, and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months postsurgery, the animals were euthanized for further ex vivo qualitative histopathologic and micro-CT evaluations. Fusion rates were compared using the Fisher exact test at each time point.Results.Increased interbody bony fusion rates were observed at SBG levels (4/4) compared with control levels (0/4) evaluated by CT at 6 and 9 months postsurgery (P=0.029). Fusion was observed at all SBG levels 12 months postsurgery and at only one control level. Histopathologic evaluation confirmed high-quality interbody bony fusion at all SBG levels and fusion by spondylosis at one control level.

Conclusion: This proof-of-concept study provides preliminary evidence of a novel, calcium pyrophosphate-containing, and beta-tricalcium phosphate-containing monetite SBG that promotes bony fusion compared with a negative control in a clinically relevant porcine model of ACDF.

Silicon nitride-based bioceramics have been investigated for biomedical applications due to their good thermo-mechanical, tribological and antibacterial properties. However, biological properties, such as bioactivity that promotes the interaction with tissue, are also important. Silicon dioxide has been found to promote bioactivity. With the aim of combining both advantages, a new Si₃N₄-SiO₂ glass ceramic was developed. Three different compositions were synthesized and sintered by spark plasma sintering. The results showed that β-Si₃N₄ crystalline is well distributed in the SiO₂ matrix. 70SiN samples exhibited the highest mechanical properties with a flexural strength of 452 ± 33 MPa and a toughness of 6.4 ± 0.5 MPa∙m^1/2. 50SiN samples exhibited the best bacteriostatic effect due to the synergistic effect of surface chemistry and topography. Apatite was observed on the surfaces of all groups. This study shows that the newly developed Si₃N₄-SiO₂ glass ceramics exhibit promising mechanical and biological properties for biomedical applications.

Injectable poly (methyl methacrylate) (PMMA) bone cements are widely used in orthopaedics to stabilize fractures and for implant fixation. However, bacterial attachment to bone cements leads to significant complications that can create a need for implant revision. Common attempts at reducing bacterial attachment are through the addition of antibiotics or antibacterial nanometals to the bone cements. However, clinical data is inconclusive on the effectiveness of antibiotic-loaded bone cements and a negative osteoblastic response has been reported for certain additive concentrations. There is therefore a need for an additive that can positively affect osteoblastic behaviour while inhibiting bacterial attachment. Silicon nitride (Si3N4) could be such an additive, with initial studies showing promise in achieving antipathogenic properties. The aim of this study was hence to investigate the possibility of creating a bone cement that can support osteoblast growth while reducing bacterial attachment by introducing silicon nitride powders into an injectable PMMA cement. To this end, commercially available bone cements were doped with 5%, 10% and 20% weight/weight (w/w) of Si3N4. Their mechanical properties were examined through compression testing and their radiopacity was evaluated through fluoroscopy imaging. The samples that fulfilled compressive strength requirements had their biological properties tested using Staphylococcus epidermidis bacteria for antibacterial properties and MC3T3-E1 preosteoblasts for the examination of cytotoxicity. Bone cements that were doped with up to 20% w/w Si3N4 were radiopaque (only 13% reduction in optical density compared to radiopaque controls) and retained their compressive strength (85.35 ± 2.1 MPa compared to 83.4 ± 1.9 MPa for the commercial cements), while significantly reducing bacterial attachment by more than 90% compared to commercial cements and achieving a similar level of preosteoblast metabolic activity. This study supports further evaluation of Si3N4 as an additive to injectable bone cements as a way to create mechanically stable, radiopaque, bacteriostatic bone cements that could improve osteointegration.

Silica-based glass ceramics have been extensively used in biomedical applications due to their superior biocompatibility and controllable properties. However, their low mechanical strength limits their application. This could be addressed by optimizing the crystalline phase which determines their final properties. Silicon nitride has attracted attention due to its combination of good mechanical and biological properties. Therefore, to combine the advantage of silica-based glass and silicon nitride ceramic, this study developed a silicon nitridesilicon dioxide (Si3N4-SiO2) glass ceramics. The effects of spark plasma sintering parameters on the structural and mechanical properties of Si3N4-SiO2 glass ceramics were investigated. Full densification was reached at a sintering temperature of 1300 degrees C, a holding time of 10 min and an applied pressure of 80 MPa (relative density = 99.19 %). No silicon oxynitride (Si2N2O) crystalline phase was formed in the sintered glass ceramics, as confirmed by XRD. The interface between the (3-Si3N4 crystalline and amorphous SiO2 was investigated by HRTEM, and the results indicated that an amorphous interfacial oxide was formed at the interface. The mechanical properties increased with increasing sintering temperature, as a result of the increased density. The Si3N4-SiO2 glass ceramics sintered at 1500 degrees C exhibited the highest value of toughness and flexural strength, at 4.6 +/- 0.28 MPa m1/2 and 360 +/- 27 MPa. The indentation cracks observed by SEM showed that the large (3-Si3N4 grains promoted crack deflection, while the equiaxed Si3N4 grains with a lower aspect ratio led to transgranular fracture. The mechanical properties of these Si3N4-SiO2 glass ceramics are comparable to commercial glass ceramics, indicating their promising aspects in biomedical applications.

Calcium phosphate crystals were synthesized via chemical precipitation with strontium (Sr) ionic doping, and starting solutions with at.% Sr 19 % (A), 40 % (B), and 53 % (C) in an acid environment (pH 6.0), resulting in the crystal without Sr with plate morphologies, sample A: Sr similar to 7.8 % and Ca similar to 92,2 % with plate+petaloid crystals, sample B showed two morphological groups: Sr similar to 12,5 % and Ca similar to 87,5 % (B-1) with plate+petaloid crystals and with Sr similar to 32,5 % and Ca similar to 67,9 % (B-2) with petaloid+pseudo-hexagons crystals, and sample C: Sr similar to 48,8 % and Ca similar to 51,2 % with higher symmetric hexagonal crystals. The samples were characterized by X-ray diffraction, SEM, and EDS. The calcium phosphate crystallographic phase family (Ca-P) includes brushite (DCPD), monetite (DCPA), and hydroxyapatite (HAP) surrounding the nucleating crystals that had plate, petaloid, and pseudo-hexagonal or hexagonal morphologies. Crystal growth nucleation by Sr inclusion ions induces preferential orientation with overlapping layer plates forming pseudo-hexagonal or hexagonal crystals with high symmetry when there is ion equilibrium between Ca and Sr. This result indicates biomimicry crystals found in nature (abalone gastropod shell), resulting in promising materials for further advances in mechanical properties and performance.

This paper describes novel and innovative amorphous calcium magnesium fluoride phosphate (ACMFP) core-shell microparticles that may be applied in preventive dentistry for the prevention of caries and the treatment of dentin hypersensitivity. The particles can be synthesized with varied fluoride content, up to approximately 6 wt%, without any observable differences in morphology or crystallinity. Fluoride release from the particles is correlated to the fluoride content, and the particles are readily converted to fluoride-substituted hydroxyapatite or fluorapatite in a simulated saliva solution. The remineralization and dentin tubule occlusion potential of the particles was evaluated in vitro on acid-etched dentin specimens, and treatment with the ACMFP particles resulted in complete tubule occlusion and the formation of a dense mineralization layer. The acid resistance of the mineralization layer was improved compared to treatment with analogous particles without fluoride inclusion. A cross-sectional evaluation of dentin specimens after treatment revealed the formation of high aspect ratio fluorapatite crystals and poorly crystalline hydroxyapatite, respectively. The particles of the current study provide a single source vehicle of readily available calcium, phosphate, and fluoride ions for the potential remineralization of carious lesions as well as exposed dentin tubules for the reduction of hypersensitivity.