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Discusses the synthesis of nanocrystalline hydroxyapatite powders in stimulated body fluid (SBF). Use of hydroxyapatite to manufacture biomaterials for bone tissue implantation; Similarity between in vitro and in vivo behavior of certain glass-ceramic compositions; Concentration of prepared SBF.

• Interaction mechanisms between dislocations and irradiation-induced defects revealed. • Atomically-informed evolution formula for dislocations and defects established. • Creation of crystal plasticity model (CPFEM) incorporating MD-derived formula. • Successful simulation of nano-indentation, tension, and compression processes. • Practical implications for predicting irradiated tungsten behavior. Tungsten plays a significant role in the nuclear industry, in which defects are generated upon exposure to irradiation. Irradiation-induced defects, such as dislocation loops and helium bubbles, are key factors in performance degradation, leading to irradiation hardening and embrittlement. The inner interaction between the dislocations and irradiation-induced defects directly determines the safety of the irradiated tungsten. However, the interaction mechanisms and evolutionary formulas remain unclear. In this study, based on systematic molecular dynamics (MD) simulations, an interaction mechanism phase map between the dislocation and dislocation loop was built as a function of the dislocation loop size and temperature. An atomically-informed mechanism-based evolution formula for dislocations and dislocation loops due to their interaction was established. Subsequently, a crystal-plasticity finite-element model (CPFEM) that contains the evolution formula obtained by MD is proposed. Based on CPFEM, the nano-indentation, uniaxial tension, and compression processes were simulated. Good agreement was achieved between the simulated and experimental results, further demonstrating the reasonability of the proposed model. [ABSTRACT FROM AUTHOR]

The microstructure and compositional tunability of hydroxyapatite (HA) microspheres, as well as their limited biodegradability, have been challenges for their use as carriers in drug delivery systems. In this study, strontium-doped HA (Sr-HA) microspheres with interconnected porosity and pore channels were successfully prepared under the regulation of Sr2+ via a hydrothermal method. The morphologies, scales, constituents, and pore geometries of Sr-HA microspheres were modulated by the concentration of Sr2+. SEM and TEM observations revealed that diverging, dense flower-like, hierarchical porous, and trumpet-shaped macroporous microspheres were obtained as Sr/(Sr + Ca) ratio increased. Correspondingly, the size of the microspheres decreased from approximately 120 μm–15 μm. The introduction of Sr2+ significantly enhanced the biodegradability of the microspheres. Furthermore, the porous Sr-HA microspheres showed superior vancomycin loading capacity (167.5 mg/g) and sustained release properties. This possible microstructure regulation mechanism was discussed based on the experimental results. This study provides a new perspective on material design for various potential applications. [ABSTRACT FROM AUTHOR]

• Developed a micro‑meso-macro framework for RPV steel. • Predicted ART for RPV steel over 40 and 60 years. • Demonstrated correlation between irradiation and DBTT. • Evaluated yield stress changes under varied temperatures and irradiation dose. • Applied CPFEM for nano-indentation simulation. Irradiation can induce microscopic defects in reactor pressure vessel (RPV) steel, resulting in macroscopic hardening and embrittlement. This paper proposes a micro‑meso-macroscale calculation framework for the mechanical properties of irradiated RPV steel based on experimental and numerical investigations. The mean size and number density of Fe-ion-irradiation-induced dislocation loops were measured using transmission electron microscopy (TEM). These parameters were described by a power-function relationship with the irradiation dose at various temperatures and were used as input parameters for the crystal plasticity finite element model (CPFEM). Nano-indentation tests of A508-Ⅲ steel under different irradiation conditions were successfully simulated. In addition, microstructural characterization and molecular dynamics (MD) simulations revealed the phenomenon of dislocation pinning and the sweeping of irradiation defects during dislocation migration, implying that the dislocation-loop interactions could be responsible for the formation of dislocation channels and curved dislocation lines. Furthermore, increase in yield stress and the ductile-brittle transition temperature (DBTT) at various temperatures were investigated. Results indicated that yield stress, DBTT, and the degree of irradiation hardening and embrittlement increased with the irradiation dose and decreased with irradiation temperature. Finally, the adjusted reference temperature (ART), a significant design parameter for nuclear reactors, was calculated and evaluated using the multiscale framework. The framework can serve as a reference text for extending the life of nuclear reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] Sandblasting micromachines titanium in favorable combination of microroughness and microhardness. [•] Ca- and P-containing coating is deposited on titanium by optimized composite technique. [•] Sandblasting promotes properties of titanium MAO coatings. [•] Nanostructure hydroxyapatite is deposited on as-prepared coating in SBF. [ABSTRACT FROM AUTHOR]

F321 stainless steel is renowned for its outstanding mechanical properties and corrosion resistance, making it a crucial structural material in light water reactors and high-temperature gas reactors. With irradiation (IR), F321 stainless steel undergoes microstructural alterations, such as the formation of IR-stimulated defects (e.g., stacking fault tetrahedrons (SFTs), dislocation loops (DLs), and clusters), resulting in IR hardening. This study compares the IR-stimulated hardening in the austenitic and ferritic phases of F321 stainless steel through both experimental methods and numerical simulations. In the austenitic phase, the size and number density of IR defects (DLs and SFTs) were determined, which were proportional to the IR dose. In the ferritic phase, IR-induced DL parameters were quantified, and the effects of IR on spinodal decomposition were analyzed. The interaction processes and mechanisms between dislocations and IR defects in the austenitic phase were evaluated using molecular dynamics (MD) simulations, leading to the development of a model for IR defect-induced hardening strength. Additionally, an MD data-driven crystal-plasticity-finite-element-model (CPFEM) was established. The nano-indentation hardness of the austenitic and ferritic phases was measured and calculated through both experimental methods and CPFEM simulations. The results show that the nano-indentation hardness of the ferritic phase is reduced compared to the austenitic phase, due to a lower density of IR defects. Understanding these effects provides deeper insights into how IR influences the mechanical and microstructural properties of F321 steel, which is essential for predicting the material's long-term performance and reliability. [Display omitted] [ABSTRACT FROM AUTHOR]

Strontium (Sr) substitution into calcium phosphate (CaP) materials has gained acceptance in research into the enhancement of physiochemical and osteogenic potential. Conventional synthesis of metal cationic substitution into CaP coatings on metal substrate usually takes relatively high temperature (﹥100 °C) and hours of processing time. Herein, a mild phosphate chemical conversion method was developed for preparing Sr-substituted CaP coatings on surface of titanium (Ti) in the presence of increasing amount of Sr (40–60 mol%). The results indicated that the complete and even coatings could be produced on the whole surface of Ti only within 50–60 % Sr and the coatings represented a unique lamellar texture in micro/nano-scale. As Sr concentration increased, the phases of coatings were predominantly indexed to monetite and SrHPO 4 , which presented a highly oriented crystal alignment. With high content of Sr, monetite, instead of brushite, was deposited in the coatings. The possible mechanism of coating formation was proposed that α-SrHPO 4 and α-monetite were co-deposited in the acidic phosphating solution and finally a compound of (Ca x Sr 1-x)HPO 4 was produced on surface of Ti. Results revealed that coatings formed at high degree of Sr substitution exhibited relative improved mechanical and electrochemical properties. The coatings enhanced the cell focal adhesion and proliferation of BMSCs compared with that of the bare Ti. [Display omitted] • Sr-substituted CaP coating was yielded on Ti by mild phosphate chemical conversion. • The coating presented unique lamellar interwoven microstructure • CaP precipitated on Ti prior to SrP in the acidic phosphate solutions. • Exceeded Sr conduced precipitation of monetite instead of brushite in the coating. • The coating performed better contact guidance to the cells compared with bare Ti. [ABSTRACT FROM AUTHOR]

[Display omitted] • A bioactive composite film is in-situ constructed on titanium by induction heating. • Oxygen vacancies play an important role in the doping of N atoms. • The formation mechanism of the laminated nanostructure layer is discussed. • The modified layer exhibits superior corrosion resistance and cellular response. To meet the requirements for good mechanical properties, corrosion resistance, and osseointegration of human hard tissue substitutes and prostheses, a bioactive and stable surface is essential. In this work, in-situ construction of a TiO 2 /TiN composite film on titanium is achieved by induction heating at a high temperature under the O 2 + N 2 atmosphere. Furthermore, the surface of the composite film contains abundant oxygen vacancies, which is demonstrated by X-ray photoelectron spectroscopy (XPS) analysis. Transmission electron microscopy (TEM) and focus ion beam (FIB) milling technology are used to further study the cross-sectional microstructure and composition, revealing the formation mechanism of the composite film. The results of the nanoindentation and electrochemical test show that the hardness and corrosion rate of the composite film are 3.45 and 0.2 times that of titanium respectively. Moreover, the composite film is favorable for the deposition of hydroxyapatite in simulated body fluid (SBF). The results of the in vitro cellular experiments demonstrate that the composite film significantly promotes the adhesion, proliferation, and differentiation of BMSCs. Overall, the composite film is desirable for its improved biocompatibility, corrosion resistance, and mechanical properties, enabling it to have potential applications in the biomedical field. [ABSTRACT FROM AUTHOR]

Titanium (Ti)-based implants with micro/nano multiscale structures have been highlighted in dental and orthopedic fields due to the enhanced osteogenic abilities and mechanical interlocking. In this study, induction heating treatment (IHT) was developed to superimpose nano structure on microrough sandblasted and acid-etched (SLA) Ti6Al4V surface. The influences of SLA and IHT on the phase compositions, microstructures, properties, and formation mechanism of the coatings were explored. IHT for 12, 18 and 24 s realize the transformation of initially generated nanodot-like crystallites into a relatively uniform and high density of nanoscale protuberances. The oxide coating obtained by SLA + IHT has larger grains compared with that obtained by IHT separately. The nanoscale protuberances comprise crystalline rutile TiO 2 and a small amount of α-Al 2 O 3. IHT results in a successive increase of roughness on smooth surface with extension of IHT period, while samples induction heated for 18 and 24 s following SLA retain the initial microscale roughness of SLA surface. Since the larger porosity inside the oxide and local plastic deformation from SLA enhance adsorption and interaction ability of Ti6Al4V with oxygen, the thickness of oxide coating obtained by SLA + IHT increases to 861 nm compared with the 408 nm formed by IHT for 24 s. The micro/nano-structured oxide coating is in favor of improving the hydrophilicity of SLA surface in terms of the decreased contact angle from 129.4° to 69.1°, and shows good capability to induce hydroxyapatite deposition in simulated body fluid. • Oxide coatings with microscale cavities and nanoscale protuberances were developed on the Ti6Al4V surface by SLA + IHT. • SLA induces IHT oxide coatings thicker and more nanopores inside. • IHT turns hydrophobic SLA surface to hydrophilic surface, while retaining the starting microscale roughness. • The micro/nano-structured oxide coating exhibits good ability to induce hydroxyapatite deposition in simulated body fluid. [ABSTRACT FROM AUTHOR]

Bioactive phosphate coatings based on hopeite (HP, Zn 3 (PO 4) 2 ·4H 2 O) and strontium‑zinc-phosphate (SZP, SrZn 2 (PO 4) 2) phases have attracted extensive attention in the surface modification of metallic implants. Nevertheless, further clarifications on the synergistic effect of HP and SZP, as well as the phase evolution between them are still needed. Herein, a chemical conversion technique was utilized to prepare composite phosphate coatings containing HP and SZP on titanium (Ti). The effect of phosphating temperature on the phase, properties, and deposition mechanism of the coatings was investigated. The results showed that the coating obtained at 50 °C was composed of HP with minor SZP crystals, while their relative contents were reversed at 80 °C. The elevated temperature also changed the crystal morphology of SZP from ellipsoidal to cubic. These variations could be attributed to the enhanced priority of Sr and Zn ions to form bimetallic-phosphate (SZP), which has a different lattice structure from HP crystal. In addition, the HP/SZP composite coating formed at 60 °C exhibited superior comprehensive properties like roughness, wettability, bonding strength, ion release, and corrosion resistance. Overall, this study elucidates the temperature-induced phase evolution and properties of HP/SZP composite coatings, which facilitates the optimal regulation of phase composition to achieve desired properties. • Zn 3 (PO 4) 2 ·4H 2 O and SrZn 2 (PO 4) 2 composite coating was developed on Ti using PCC technique. • SrZn 2 (PO 4) 2 crystal tends to form at higher temperatures compared with Zn 3 (PO 4) 2 ·4H 2 O one. • The SrZn 2 (PO 4) 2 crystal varied from ellipsoidal to cubic at elevated temperatures. • The composite coating obtained at 60 °C has better mechanical and surface characteristics. [ABSTRACT FROM AUTHOR]

The microstructure of the phosphate coating on implant surface is critical for successful osseointegration. Based on the morphological variability of phosphate crystals, the microstructure of the coating can be regulated by designing the composition of the phosphate solution. In this study, a strontium‑zinc-phosphate (SrZn 2 (PO 4) 2 , SZP) coating was prepared on titanium (Ti) surface by phosphate chemical conversion (PCC) method. The effect of Zn2+ concentration in phosphate solution, which was regulated by increasing the addition amount of Zn(H 2 PO 4) 2 ·2H 2 O, on the microstructure and properties of the SZP coating was investigated. The characterization of the coating was carried out by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrometer (XPS), laser scanning confocal microscope (LSCM), contact angle goniometer, and electrochemical workstation system. The results revealed that the increase of Zn2+ concentration in phosphate solution could induce the crystal morphology of the SZP coating to evolve from irregular granules (Zn(H 2 PO 4) 2 ·2H 2 O: 1 g/L) to regular cubic blocks (Zn(H 2 PO 4) 2 ·2H 2 O: 8 g/L). This morphological evolution process was accompanied by an increase in thickness (from 4.8 ± 1.2 to 20.6 ± 1.9 μm), an improvement in wettability and corrosion resistance, as well as a decrease in the release amount of Sr2+ (from 3.97 ± 0.26 to 0.86 ± 0.12 ppm) and Zn2+ (from 0.31 ± 0.01 to 0.18 ± 0.01 ppm) after 21 days of immersion. In vitro evaluations proved that the adhesion, proliferation, and differentiation of MC3T3-E1 pre-osteoblasts on SZP coatings, especially for the coating with tiny cubic-block crystals, were significantly enhanced compared with pure Ti. This study clarified the rule of morphological evolution of the SZP crystal that is caused by changing the Zn2+ concentration in the phosphate solution, which contributes to the structural optimization of the SZP coating to obtain high osteogenic activity. [Display omitted] • A SrZn 2 (PO 4) 2 coating was prepared on titanium using chemical conversion method. • The coatings microstructure depended on the Zn2+ concentration in phosphate bath. • The coatings with cubic crystal morphology showed preferable osteogenic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Structural evolution of oxide layers on Ti6Al4V surfaces were achieved by conducting cold-compression and induction heating. • Metallographic microstructures determined the size and structures of oxide crystallites formed via a seeding mechanism. • The formation of submicroscale TiO 2 crystallites considerably improved the HAp deposition in vitro. • The promotion effect of oversized oxide crystallites on HAp deposition was diminished. Considerable efforts have been devoted to the construction of micro- and nanostructured surfaces to improve the clinical application of Ti-based orthopedic implants. However, the preparation of bioactive microstructures with tunable characteristics remains challenging. Herein, we investigated the structural evolution of oxide layers on Ti6Al4V surfaces by conducting a cold compression and induction heating protocol. We found that the properties of the metallographic microstructures determined the size and structure of oxide crystallites formed via a seeding mechanism: the finer the matrix grains, the smaller the oxide crystallites. In addition, the alloy matrix grain sizes steadily increased with increasing axial compression because of recrystallization during induction heating. The formation of nanoscale rutile (TiO 2) crystallites caused an increase of surface roughness and hardness, and considerably improved the bioactivity of Ti6Al4V, as measured by the degree of hydroxyapatite deposition in simulated body fluid in vitro. However, oversized oxide crystallites had a negative effect on the promotion of hydroxyapatite deposition. This important finding offers a feasible method for the controllable in-situ construction of bioactive oxide layers by designing the required matrix microstructures of Ti-based implant materials. [ABSTRACT FROM AUTHOR]

Phosphate chemical conversion coatings have attracted much attention on surface modification of metallic implant, due to their in-situ growth pattern and good mechanical performances. Nevertheless, it is difficult to use this method for preparing a pure hydroxyapatite (HA) coating. In this study, a pure HA coating was prepared on titanium (Ti) in an acidic phosphate aqueous via a simple single-step chemical conversion without alkali post-treatment. The microstructure, chemical composition, electrochemical and mechanical performances of the HA coating were characterized in comparison with those of a precursor dicalcium phosphate (CaP) coating which was alkali post-treated (CaP-OH). Results revealed that the one-step chemically converted HA coating was homogeneously nano-structured with higher phase purity and crystallinity. Moreover, the HA coating was thicker (~6.5 μm) than the CaP-OH one (~40 μm) but with better mechanical properties and corrosion resistance. The results encouraged the direct preparation of crystalline HA coating with superior properties on surface of Ti via a single-step phosphate chemical conversion. • A one-step preparation of HA coating on titanium is proposed using chemical conversion technique. • The HA coating is nanostructured with higher phase purity and crystallinity compared to the two-step prepared one. • The HA coating performs better in the mechanical and electrochemical characteristics. • Both the nucleation and morphology of the HA crystals are influenced by the ultrasonic irradiation. [ABSTRACT FROM AUTHOR]

Titanium (Ti) and its alloys are believed to be promising scaffold materials for dental and orthopedic implantation due to their ideal mechanical properties and biocompatibility. However, the host immune response always causes implant failures in the clinic. Surface modification of the Ti scaffold is an important factor in this process and has been widely studied to regulate the host immune response and to further promote bone regeneration. In this study, a calcium-strontium-zinc-phosphate (CSZP) coating was fabricated on a Ti implant surface by phosphate chemical conversion (PCC) technique, which modified the surface topography and element constituents. Here, we envisioned an accurate immunomodulation strategy via delivery of interleukin (IL)-4 to promote CSZP-mediated bone regeneration. IL-4 (0 and 40 ng/mL) was used to regulate immune response of macrophages. The mechanical properties, biocompatibility, osteogenesis, and anti-inflammatory properties were evaluated. The results showed that the CSZP coating exhibited a significant enhancement in surface roughness and hydrophilicity, but no obvious changes in proliferation or apoptosis of bone marrow mesenchymal stem cells (BMMSCs) and macrophages. In vitro, the mRNA and protein expression of osteogenic related factors in BMMSCs cultured on a CSZP coating, such as ALP and OCN, were significantly higher than those on bare Ti. In vivo, there was no enhanced bone formation but increased macrophage type 1 (M1) polarization on the CSZP coating. IL-4 could induce M2 polarization and promote osteogenesis of BMMSCs on CSZP in vivo and in vitro. In conclusion, the CSZP coating is an effective scaffold for BMMSCs osteogenesis, and IL-4 presents the additional advantage of modulating the immune response for bone regeneration on the CSZP coating in vivo. • A chemical conversion calcium-strontium-zinc-phosphate (CSZP) coating is prepared on titanium. • The CSZP coating exhibits micellar lamellar crystal morphology in micro-nano scale. • The CSZP coating has an optimal topography and element composition for osteogenesis. • Interleukin-4 assisted CSZP coating can obtain better osteoimmunomodulation properties. [ABSTRACT FROM AUTHOR]

Current development of nano/microscale modification technology of Ti-based implants was focused on the acceleration of ossification and consequent reduction of immunological rejection after implantation. Here, we rationally designed and produced the multistructures with microscale etched pits and nanodot-like oxide crystallites using, a two-step method, HF/HCl etching and induction heating treatment (IHT). IHT oxidation achieved the initially generating of nanocrystallites on the microscale surface and continually growing into dense spherical particles. The dual-scale oxide structures mostly contained rutile-TiO 2 with mixture thickness of 402 nm, and remarkably improved the surface wettability with surface roughing. The oxide multistructures showed favorable osteogenic differentiation of human bone marrow-derived mesenchymal stem cells with promoting expressions of osteogenesis-related genes (ALP, Runx2, OCN and COL-1) and proteins. Otherwise, it practically confirmed that the stem cells owned relatively weak 24 h cell adhesion and proliferation on the special oxide structures via comparation with histiocytic types (ST2 cells), and the samples acquired better cell fates when oxidized for 30 s than 20 s due to the larger surface roughness and better hydrophilicity. This study provided theoretical and experimental foundations for construction and further clinical application of high-performance bone implants with multistructures. Unlabelled Image • Oxide layers with microscale etched-structures and nanodot-like oxide crystallites were rapidly prepared by A + IHT protocol. • A + IHT approach increased the roughness value, and improved the hydrophilicity and adherence strength of oxide layers. • The micro/nanoscale oxide structures advanced proliferation and osteogenic differentiation of BMSCs without cytotoxicity. • Stem cells had different osteogenic behaviors with weak cell attachment and growth patterns compared to the histiocytic types. [ABSTRACT FROM AUTHOR]

Titanium (Ti) and its alloys are widely used as hard tissue substitutes in dentistry and orthopedics, but their low bioactivity leads to undesirable osseointegration defects in the early osteogenic phase. Surface modification is an important approach to overcome these problems. In the present study, novel magnesium phosphate (MgP) coatings with controllable structures were fabricated on the surface of Ti using the phosphate chemical conversion (PCC) method. The effects of the microstructure on the physicochemical and biological properties of the coatings on Ti were researched. The results indicated that accelerators in PCC solution were important factors affecting the microstructure and properties of the MgP coatings. In addition, the coated Ti exhibited excellent hydrophilicity, high bonding strength, and good corrosion resistance. Moreover, the biological results showed that the MgP coatings could improve the spread, proliferation, and osteogenic differentiation of mouse osteoblast cells (MC3T3-E1) and vascular differentiation of human umbilical vein endothelial cells (HUVECs), indicating that the coated Ti samples had a great effect on promoting osteogenesis and angiogenesis. Overall, this study provided a new research idea for the surface modification of conventional Ti to enhance osteogenesis and angiogenesis in different bone types for potential biomedical applications.

A three-dimensional (3D) porous network can be prepared on the PEEK surface by sulfonation with enhanced osseointegration and antibacterial properties. However, few studies have been conducted on the formation mechanism of a 3D porous network. In this work, the surface and cross-sectional morphologies, chemical compositions, functional groups, surface wettability, and crystalline states of sulfonated PEEK were investigated at different sulfonation times and coagulant concentrations. The results show that the number of nodular structures and broken fibers on the sulfonated PEEK surface as well as the size of macrovoids in the cross sections increase with increasing sulfonation times when water is used as a coagulant. In contrast, dilute sulfuric acid as a coagulant can inhibit the formation of surface porous structures and macrovoids in the cross sections. Moreover, all of the sulfonated PEEK samples have the same chemical compositions but exhibit better hydrophilicity as the number of microsized pores decreases. It is proposed that non-solvent-induced phase separation (NIPS) occurs during the sulfonation process, and the formation mechanism of surface and cross-sectional morphologies is discussed. Furthermore, it is assumed that the air is trapped in the microsized pores, leaving the surface of the 3D porous network in the Cassie-wetting state. All of these preliminary results throw light on the nature of the sulfonation process and may guide further modification of the structures of sulfonated PEEK.

Great effort has recently been devoted to the preparation of nanoscale surfaces on titanium-based implants to achieve clinically fast osteoinduction and osseointegration, which relies on the unique characteristics of the nanostructure. In this work, we used induction heating treatment (IHT) as a rapid oxidation method to fabricate a porous nanoscale oxide layer on the Ti6Al4V surface for better medical application. Well-distributed vertical nanopillars were yielded by IHT for 20-35 s on the alloy surface. The composition of the oxides contained rutile/anatase TiO 2 and a small amount of Al 2 O 3 between the TiO 2 grain boundaries (GBs). This technology resulted in a reduction and subsequent increase of surface roughness of 26-32 nm when upregulating the heating time, followed by the successive enhancement of the thickness, wettability and adhesion strength of the oxidation layer to the matrix. The surface hardness also distinctly rose to 554 HV in the IHT-35 s group compared with the 350 HV of bare Ti6Al4V. The massive small-angle GBs in the bare alloy promoted the formation of nanosized oxide crystallites. The grain refinement and deformation texture reduction further improved the mechanical properties of the matrix after IHT. Moreover, in vitro experiments on a mesenchymal stem cell (BMSC) culture derived from human bone marrow for 1-7 days indicated that the nanoscale layers did not cause cytotoxicity, and facilitated cell differentiation in osteoblasts by enhancing the gene and osteogenesis-related protein expressions after 1-3 weeks of culturing. The increase of the IHT time slightly advanced the BMSC proliferation and differentiation, especially during long-term culture. Our findings provide strong evidence that IHT oxidation technology is a novel nanosurface modification technology, which is potentially promising for further clinical development.

Objective: To study the influence of the screw thread and the height of constraints on the stress distribution of the implants., Methods: The three-dimensional emulational models of the implants with different screw-pitch were constructed by a CAD/CAM package. The Von Mises stress of the models was analyzed by three-dimensional finite element method., Results: The constraints of the long implant were high. When the constraint height reduced, the change of the stress value of the implants without screw thread was much less than that of the implants with screw thread. The difference of screw-pitch had little influence on the stress value and the stress concentration of the implants., Conclusion: The strength requirement of screw implant was high. Stress distribution of the long dental implants was more reasonable than the other, which will contribute to the success of dental implants.