Bang Cheng Yang

Preparation of Bioactive Tantalum Metal via Anodic Oxidation Treatment

After the Tantalum metal was subjected to the anodic oxidation at suitable voltage in 2M H2SO4 solution, tantalum oxide with rhombic or amorphous structure formed on the metal surface. The Oxide showed apatite formation ability in simulative body fluid at 6d. It meant the anodic oxidation treatment ia an effective method to accelerate the bioactivity of tantalum metal.

3D Finite Element Analysis of Bone Stress around Distally Osteointegrated Implant for Artificial Limb Attachment

Stress shielding, which occurred always around traditional one part implant applied for prosthetic artificial lower limb attachment, would cause osteoporosis and thus result in the loose and extrusion, and then the malfunction of the implant. To improve the structure of the implant, a new type of implant—multi-part implant was developed in this article. Based on CT data and under the maximal load during a normal walking cycle, 3D finite element analysis (FEA) was carried out to analyze the stress of bone around the new implant in three cases of distally truncated femur at high position、middle-position and low-position. Results reveal that stress shielding and stress concentration under the new type of implant reduced effectively compared with the traditional one-part implant, and the stress distribution is much close to the natural bone. Application for distally truncated femur at middle-position and low-position was much better, while stress concentration was marked at high-position. Meanwhile, the stability in vivo can also be maintained with the multi-part implant. The new implant is promising applied for prosthetic limb.

The Influence of Bovine Serum Albumin on the Biomimetic Calcium Phosphate Coating of Bioactivated Titanium

In this study, bovine serum albumin protein (BSA) was introduced to investigate the co-precipitation process of calcium phosphate and BSA on bioactivated Ti. Commercially pure titanium were bioactivated firstly, and then immersed in a highly supersaturated stable calcium phosphate (Ca-P) solution at three different conditions. The samples designated as Ti-C, Ti-C-CB, and Ti-C-B for control. The samples were evaluated by SEM with EDX, XRD and XPS. The co-precipitation of BSA protein and Ca-P influenced the morphology of the crystals of Ti-C-CB significantly. In terms of the immersion in the Ca-P solution containing BSA, the co-precipitation of Ca-P with BSA on the surface of Ti-C-CB was a chemical process rather than simple physical adsorption, which was most possibly achieved by the linkage of –COO− groups to Ca-P. Such coprecipitated interaction led to the formation of a tight, dense and uniform Ca-P coating.

Tissue Responses to Titanium with Different Surface Characteristics after Subcutaneously Implanted in Rabbits

The objective of this study was to investigate the soft tissue responses to titanium with different surface characteristics. Titanium bars with three kinds of surface were available to be anchored in the femur bone of rabbits and then penetrated into the soft t issue just under the skin: hydroxyapatite (HA) coated Ti, anode-oxidized Ti and sandblasted Ti a s control. After 4 weeks and 8 weeks, the implants with surrounding soft tissue were retrieved a nd processed mechanically and histologically. All samples were encapsulated with quite thin f ibrous capsules and little inflammatory reaction was observed except the sandblasted bars. At 4 weeks postoperation, the histological reaction and the attachment strength of the anode oxidi zed group was similar to the HA coated group. But at 8 weeks postoperation, the histological response arou nd the HA coated group was better than at the anode oxidized group and the attachment stren g h was almost three times more. The sandblasted bars attached the soft tissue so weakly that it was too difficult to test the push-out strength. The SEM-EDX micrographs showed that a layer of calcium phosphate emerged at the interfaces between soft tissue and implants except sandbl aste Ti, so we can infer that the layer of calcium phosphate plays a very important role in impr oving the soft tissue integration with the titanium. Introduction For percutaneous devices (PD) anchored in bone, the major failure mod s are marsupialization and infection, which are resulted from skin downgrowth and mechanical dam age [1]. In order to avoid these phenomena occurring, the implant’s surface could be bioactivated to facilitate its firm attachment and bonding with the soft tissue under the skin, which is one of th main methods to inhibit the epithelial downgrowth. [2,3] Titanium and titanium alloys a re increasingly being used as PD implants as a result of their excellent bulk properties and bi ocompatibility. [3,4] But up to now, there are few reports available concerning soft tissue response s to the bioactivated surface of Ti. In this paper, three kinds of titanium bars with different surfaces cha ra teristics were subcutaneously implanted in rabbits to study their soft tissue responses, including the attachment strength of implant-tissue interface. Materials and Methods Commercially pure titanium was cut into cylinder bars 3 x12mm. Half part of the bar along the long axis was screwed and the other part was modified with two di fferent bioactivation methods or sandblasted. The first group of bars, defined as HAC group, was plasma sprayed with Key Engineering Materials Online: 2003-12-15 ISSN: 1662-9795, Vols. 254-256, pp 725-728 doi:10.4028/www.scientific.net/KEM.254-256.725

Mechanical Properties on Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding

To eliminate thermal stress during laser cladding and to raise the bonding strength between substrate and coating, composition gradient coatings are designed and fabricated by using wideband laser cladding technique on a Ti alloy. And mechanical properties on coating is studied. The experimental results indicate that the bonding strength between coating and substrate is fairly high, above 38.8MPa. The highest microhardness is obtained for coating containing 0.6wt.% Y2O3 1062HV0.1 and 1405HV0.1, respectively at bioceramic coating and alloyed transition layer. The average tensile strength, bending strength, and elastic modules of coatings are 767.83MPa, 1671.65MPa, and 13.98GPa, respectively.

A Study on the Bioactivity of Nano-Titania/Hydroxyapatite Composite

The bioactivity of a composite of titania and hydroxyapatite was studied in vitro in this paper. After the titania ceramics was added 10% HA, it could induce apatite formation in simulated body fluid in 2d, while the pure titania ceramics could not induced apatite formation even after 14d. After the composite of titania and HA was subjected to alkali-heat treatment, it has a faster speed for apatite formation in SBF than the composite without treatment. When the osteoblast was cultured on the materials, the amount of osteoblasts attaching on the composite was more than that on the pure titania ceramics. It has the most osteoblasts cells on the composite subjected to alkali-heat treatment. These results showed that the composite of titania and HA is a bioactive materials, while the alkali-heat treatment could improved the bioactivity of this composite.

Microstructure and Biocompatibility of Gradient Bioceramic Composite Coating Fabricated by Wide-Band Laser Cladding

In this study, microstructure and biocompatibility of gradient bioceramic composite coating fabricated by Wide-Band Laser Cladding is investigated. The experimental results indicate that the coating consists of an alloyed transition layer and the bioceramic coating. The bioceramic coating is mainly comprised of HA, CaTiO3, CaO, α-TCP, β-TCP and TiO. The coral-shaped structure and short-rod piled structure existing on the surface of coating. After the implantation of the bioceramic coatings into dogs’ femur for 6, 12, and 24 weeks, hypersusceptibility, rejection and pathological changes are not found. No fiber cyst, necrosis of bone tissue and chronic inflammation obviously appear through slice observation of hard tissues. The bioceramic coating with different ratios of Ca : P have different abilities to induce osteogenesis. At Ca: P=1.4 and 0.6wt.% Y2O3 (No.3 sample), the bioceramic coating is of best bioactivity and biocompatibility.

Biomimetic Coating on Titanium Metal and Its Excellent Cell Proliferation

Biomimetic coating on roughed titanium plates were prepared in this work by a cathode deposition method in calcium phosphate solution electrolyte. The coatings of plate-like apatite crystals were deposited on the titanium plates under a constant potential of 2.0V for 60 min at 37. The coating crystals were identified to be carbonate-containing apatite (bone-like apatite) by X-ray diffraction and scanning electronic microscopy. The cell proliferation and adhesion of L929 cells on the titanium metal plates with biomimetic coating and the titanium plates with roughed-only were tested. The results showed that biomimetic coating on titanium surface can enhance the materials bioactivity. The study indicated that cathode method is potential to prepare biomimetic coating on titanium implants with excellent bioactivity.

The Effect of Post-Treatment on the Mechanical Behavior of Plasma Sprayed HA Coating

Plasma-sprayed hydroxyapatite coating on metal substrate has been prepared, two kinds of post-treatment methods have been used: (1) Heating in air at 650°C for 30 min, (2) Heating in water vapor at 125°C, 0.15Mpa for 6 hours. XRD showed that the nanocrystals of HA coating increased after water vapor treated. The interfacial tensiles strength between HA and the substrate were 45.0±1.82MPa, 39.1±1.27MPa and 30.3±1.61MPa for as-received coatings, water vapor treated coatings and heated in air coatings respectively. After 3 months implant in dogs limbs, the push-out strength between implants and bone were 11.27±2.71 MPa, 11.63±3.11MPa, 23.92± 2.01MPa and 18.8±1.82 MPa for pure Ti implants, as-received coating implants, water vapor treated implants and heated in air implants respectively. The results showed that the water vapor post treated HA coating have better mechanical behavior in vitro and in vivo.

The Effect of Bovine Serum Albumin on the Crystalline Characteristics of the CaP Biomimetic Coating

It is very necessary to develop a real biomimetic compound coating of CaP with organic component and investigate quantitatively the effects of different bovine serum albumin (BSA) concentration on the crystallite properties of the coprecipitated CaP layer. Bioactivated Ti was immersed in Ca-P solution with different BSA contents to obtain different biomimetic coating. The coatings were analyzed with scanning electron microscopy (SEM) and X-ray diffraction (XRD). With the increase of BSA, the crystals on the coating grew more slowly but packed more closely. The preferential crystallographic direction of 002 of hydroxyapatite became less distinguishable and the crystallinity of the deposited hydroxyapatite decreased gradually. The crystallite sizes reduced with the addition of BSA proteins. Accordingly, when a certain content of BSA protein was added to the Ca-P solution, Ti surface would form a real biomimetic coating with the crystal size and crystallinity similar to the natural bone.