Torsional properties of implant grade titanium

The purpose of this research was to evaluate the torsional strength and ductility of CP titanium in the as received condition, heat treated below the alpha----beta transition temperature, and glass bead blasted. Results were compared to as-received samples of implant quality 316L stainless steel. Little or no effect of any of the treatments was noted. The torsional strength of all titanium samples was comparable to 316L stainless and the torsional ductility of the titanium was significantly greater than 316L stainless (p less than .01). These results are significantly different than those obtained when torsion testing bone screws of the same material. A hypothesis is proposed for the differences in these results.     

Bioactive titanium implant surfaces with bacterial inhibition and osteoblast function enhancement properties

Infection in orthopedic implant surgery is a serious complication and a major cause of implant failure. Upon implant insertion, a contest between microbial colonization and tissue integration of the implant surface ensues. This race for the surface determines the probability of tissue integration or infection, and the surface properties of the substrate have an important role to play in determining the outcome. A number of strategies have been developed for the modification of implant surfaces to promote bone cell (osteoblast) functions and inhibit bacterial adhesion and growth. In this article, a review is given of these surface modification strategies, in particular those which can achieve the dual aim of bacterial inhibition and simultaneous enhancement of osteoblast functions.Surfaces of these types can be expected to have excellent potential for orthopedic applications.     

Effect of cleaning and sterilization on titanium implant surface properties and cellular response

Titanium (Ti) has been widely used as an implant material due to the excellent biocompatibility and corrosion resistance of its oxide surface. Biomaterials must be sterile before implantation, but the effects of sterilization on their surface properties have been less well studied. The effects of cleaning and sterilization on surface characteristics were bio-determined using contaminated and pure Ti substrata first manufactured to present two different surface structures: pretreated titanium (PT, Ra=0.4 μm) (i.e. surfaces that were not modified by sandblasting and/or acid etching); (SLA, Ra=3.4 μm). Previously cultured cells and associated extracellular matrix were removed from all bio-contaminated specimens by cleaning in a sonicator bath with a sequential acetone-isopropanol-ethanol-distilled water protocol. Cleaned specimens were sterilized with autoclave, gamma irradiation, oxygen plasma, or ultraviolet light. X-ray photoelectron spectroscopy (XPS), contact angle measurements, profilometry, and scanning electron microscopy were used to examine surface chemical components, hydrophilicity, roughness, and morphology, respectively. Small organic molecules present on contaminated Ti surfaces were removed with cleaning. XPS analysis confirmed that surface chemistry was altered by both cleaning and sterilization. Cleaning and sterilization affected hydrophobicity and roughness. These modified surface properties affected osteogenic differentiation of human MG63 osteoblast-like cells. Specifically, autoclaved SLA surfaces lost the characteristic increase in osteoblast differentiation seen on starting SLA surfaces, which was correlated with altered surface wettability and roughness. These data indicated that recleaned and resterilized Ti implant surfaces cannot be considered the same as the first surfaces in terms of surface properties and cell responses. Therefore, the reuse of Ti implants after resterilization may not result in the same tissue responses as found with never-before-implanted specimens.     

Osteointegration of titanium implant is sensitive to specific nanostructure morphology

An important aspect of orthopedic implant integration is the enhancement of functional activity of osteoblasts at the tissue-implant interface without any fibrous tissue intervention. Nanostructured implant surfaces are known to enhance osteoblast activity. Previously, we have reported a simple hydrothermal method for the fabrication of non-periodic nanostructures (nanoscaffold, nanoleaves and nanoneedles) on titanium implants showing good biocompatibility and a distinct osteoblast response in vitro in terms of osteoblast adhesion to the surface. In the present work, these nanostructures have been evaluated for their detailed in vitro cellular response as well as in vivo osteointegration. Our studies showed that a specific surface nanomorphology, viz. nanoleaves, which is a network of vertically aligned, non-periodic, leaf-like structures with thickness in the nanoscale, provided a distinct increase in osteoblast cell proliferation, alkaline phosphatase (ALP) activity and collagen synthesis compared to several other types of nanomorphology, such as nanotubes, nanoscaffold and nanoneedles (rods). Gene expression analysis of ALP, osteocalcin, collagen, decorin and Runx2 showed ~20- to 40-fold up-regulation on the leaf-like topography. Cytoskeletal arrangement studies on this substrate again revealed a unique response with favorable intracellular protein expressions of vinculin, FAK and src. In vivo osteointegration study over 12 weeks on rat model (Sprague-Dawley) showed early-stage bone formation (60% bone contact by week 2 and ~85% by week 8, p<0.01) in the leaf-like nanopattern, without any inflammatory cytokine production.     

The significance of the surface properties of oxidized titanium to the bone response: special emphasis on potential biochemical bonding of oxidized titanium implant

The aim of the present study is to investigate bone tissue reactions to various surface oxide properties, in particular to different surface oxide chemistry of oxidized titanium implants (grade 1). One control and three test screw-shaped implant groups were prepared. Controls were turned implants. Test implants, i.e. S implants, P implants and Ca implants were by the micro-arc oxidation (MAO) method. The surface characterizations were performed with X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning electron microscopy, X-ray diffractometry and TopScan 3D. Eighty implants were inserted in the femora and tibiae of ten mature New Zealand white rabbits for 6 weeks. The removal torque values (RTQ) showed significant differences between S implants and controls (p=0.022), Ca implants and controls (p=0.0001), Ca implants and P implants (p=0.005) but did not show significant differences between the others (p>0.05). In addition, the bone to metal contact (BMC) around the entire implants demonstrated 186% increase in S implants, 232% increase in P implants and 272% increase in Ca implants when compared to the paired control groups. Based on the comparative analysis of the surface characteristics resulting different bone responses between all groups, it was concluded that surface chemistry and topography separately or together play important roles in the bone response to the oxidized implants.     

Electrochemical characterization of cast titanium alloys

A reaction layer forms on cast titanium alloy surfaces due to the reaction of the molten metal with the investment. This surface layer may affect the corrosion of the alloy in the oral environment. The objective of this study was to characterize the in vitro corrosion behavior of cast titanium alloys. ASTM Grade 2 CP titanium, Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys were cast into a MgO-based investment. Experiments were performed on castings (N=4) with three surface conditions: (A) as-cast surface after sandblasting, (B) polished surface after removal of the reaction layer, and (C) sandblasted surface after removal of the reaction layer. Open-circuit potential (OCP) measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air+10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was subsequently conducted in the same medium deaerated with N(2)+10% CO(2) gas 2 h before and during the experiment. Polarization resistance (R(P)) and corrosion rate (I(CORR)) were calculated. Numerical results were subjected to nonparametric statistical analysis at alpha=0.05. The OCP stabilized for all the specimens after 6 x 10(4)s. Apparent differences in anodic polarization were observed among the different surfaces for all the metals. A passivation region followed by breakdown and repassivation were seen on specimens with surfaces A and C. An extensive passive region was observed on all the metals with surface B. The Kruskal-Wallis test showed no significant differences in OCP, R(p), I(CORR) or break down potential for each of the three surfaces among all the metals. The Mann-Whitney test showed significantly lower R(P) and higher I(CORR) values for surface C compared to the other surfaces. Results indicate that the surface condition has more effect on corrosion of these alloys than the surface reaction layer. Within the oxidation potential range of the oral cavity, all the metal/surface combinations examined showed excellent corrosion resistance.     

口腔钛合金种植体的临床应用

背景：钛合金质量较轻、密度低,具有抗电化学腐蚀、良好的生物相容性、低弹性模量和高强度等优异性能,已被广泛应用于口腔医学。 目的：总结近年来口腔生物材料钛合金种植体的临床应用进展。 方法：由作者应用计算机检索1998-01/2010-10维普数据库中与口腔生物材料钛合金种植体有关的文献,检索关键词为“钛合金,种植,生物相容性”。 结果与结论：目前的研究大多数集中于钛合金种植体的生物相容性研究。国内外学者们正在努力寻求更加理想的钛合金种植体表面结构来提高种植体的骨结合能力,此对种植体骨性结合界面形成也极其重要。钛合金种植体的表面处理对提高种植成功率起着重要作用,不同处理方法都有其优点,但共同的特点是形成粗糙表面,使其具有更好的生物活性与骨结合能力。因此寻找一种能兼具各方面优点,更好促进骨结合的表面处理方法,已成为近年来口腔种植学研究的热点。     

锌对钛种植体骨融合的影响

背景：前期的研究结果表明,补锌能够提高种植体的骨愈合率以及固位强度。 目的：观察锌对种植体骨界面组织形态的影响。 方法：纳入成年雄性家兔40只,双侧胫骨近心端各置入1枚钛种植体,建立钛种植体动物模型,分为补锌组和对照组。补锌组动物肌注10 g/L硫酸锌,4 mg/kg,1次/d;对照组给予同剂量生理盐水。分别于术后1,2,4,8,12周处死动物,利用显微镜及扫描电镜观察种植体-骨界面组织形态。 结果与结论：补锌能够在钛种植体置入后1~4周内加速种植体-骨界面的新骨形成,促进种植体骨愈合。提示种植体置入后适量地补锌能够促进新骨形成,提高骨愈合的速度和质量。     

具有微弧氧化-硅烷-褪黑素复合膜层钛合金种植体的体内骨结合

BACKGROUND: Imperfect strength of titanium alloy implant-bone interface delays bone healing. OBJECTIVE: In order to further improve the early healing ability of titanium dental implants, to make the surface modification of titanium alloy implant and observe the osseointegration ability of the implant. METHODS: Titanium alloy implants were coated with micro-arc oxidation (group A), micro-arc oxidation-silane (group B), and micro-arc oxidation-silane-melatonin (group C) coatings, respectively. Three kinds of implants were placed into the mandible of New Zealand white rabbits, and 2, 4, 6 weeks after implantation, implant-bone interface osseointegration was observed using cone-beam CT, fluorescence microscopy, and torsion test. RESULTS AND CONCLUSION: (1) Cone-beam CT examination: 6 weeks after implantation, the osseointegration of the implant with the mandible achieved the best results in the group C, followed by group B and group A. (2) Fluorescence microscope observation: the implants in the three groups exhibited the strongest fluorescence at 4 weeks and slightly weakened at 6 weeks, and the fluorescence intensity was higher in the group C than the other two groups. (3) Torsion test: with implantation time prolonged, the implant-bone osseointegration activity gradually increased in the three groups, while it was still highest in the group C (P < 0.05). In summary, our results show that the titanium alloy implant coated with micro-arc oxidation-silane-melatonin composite coating has higher osseointegration activity and promotes bone formation.     

Preparation of graded porous titanium coatings on titanium implant materials by plasma spraying

Graded porous titanium coatings have been deposited on titanium substrates for dental implants by plasma spraying in an argon atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), surface roughness measurement, and tensile strength tests were performed on graded porous coatings. The results showed that Ti(3)O(5) was formed in the outermost surface of the porous coatings due to oxidation. The graded porous coatings consisted of three layers. The outer layer was full of macropores with a surface roughness of approximately 100 microm. The diameter of many macropores reached and even surpassed 150 microm, which could be beneficial for tissue to grow into the coating. The middle layer consisted of a mixture of micropores and macropores. The inner layer was a very dense and tight interface layer that included mechanical, physical, and metallurgical bonding. In tensile strength tests, testing bars peeled off the coatings, because the adhesive agent fractured, but the coatings remained intact.     

Initial tissue response to a titanium implant coated with apatite at room temperature using a blast coating method

We previously reported a blast coating method (BC method) as a new coating method of titanium (Ti) with apatite (AP) at room temperature. The BC method gives much stronger AP coating on the Ti surface compared with those obtained by other room temperature coating methods. However, no in vivo study has been made, so far, to evaluate the stability or the tissue response to the implant. As an initial step to evaluate the feasibility of the BC method, we evaluated the tissue response and stability of AP coated Ti implant prepared with the BC method (AP-BC implant) using rats as experimental animals. The AP coating adhered tightly to the Ti surface even after the implant procedure and throughout the experimental period up to six weeks post operation. AP-BC implant caused no inflammatory response, showed strong bone response and much better osteoconductivity compared with the pure Ti implant. The new bone formed on the surface of AP-BC implants was thinner compared with that formed on the surface of Ti implant. Therefore, the AP-BC implant has a good potential as an osteoconductive implant material.     

Improved implant osseointegration of a nanostructured titanium surface via mediation of macrophage polarization

The use of endosseous implanted materials is often limited by undesirable effects that may be due to macrophage-related inflammation. The purpose of this study was to fabricate a nanostructured surface on a titanium implant to regulate the macrophage inflammatory response and improve the performance of the implant. Anodization at 5 and 20 V as well as UV irradiation were used to generate hydrophilic, nanostructured TiO₂ surfaces (denoted as NT5 and NT20, respectively). Their surface characteristics and in vivo osseointegration as well as the inflammatory response they elicit were analyzed. In addition, the behavior of macrophages in vitro was evaluated. Although the in vitro osteogenic activity on the two surfaces was similar, the NT5 surface was associated with more bone formation, less inflammation, and a reduced CD68⁺ macrophage distribution in vivo compared to the NT20 and polished Ti surfaces. Consistently, further experiments revealed that the NT5 surface induced healing-associated M2 polarization in vitro and in vivo. By contrast, the NT20 surface promoted the pro-inflammatory M1 polarization, which could further impair bone regeneration. The results demonstrate the dominant role of macrophage-related inflammation in bone healing around implants and that surface nanotopography can be designed to have an immune-regulating effect in support of the success of implants.     

Biological fabrication of nacreous coating on titanium dental implant

Titanium screws with 3.5mm diameter and 8mm length, as well as titanium flat sheets with size 4 mm x 8 mm x 0.3mm, were implanted into the epithelial mantle pearl sacs of a fresh water bivalve (Hyriopsis cumingii Lea) by replacing the pearls. After 45 days of cultivation, the implant surfaces were deposited with a nacre coating with iridescent luster. The coating could conform to some extent the thread topography of the screw implant and was about 200-600 microm in thickness. The coating was composed of a laminated nacreous layer and a transitional non-laminated layer that consisted mainly of vaterite and calcite polymorphs of calcium carbonate. The transitional layer was around 2-10 microm thick in the convex and flat region of the implant surface and could form close contact with titanium surface; while the transitional layer was much thicker in the steep concave regions and could not form close contact with the titanium surface. The reasons for inhomogeneity in thickness and the variation in interface character were discussed and the improvement to the design of the dental implant with respect to this coating method was suggested in the paper. The results suggest that it is possible to fabricate a biologically active and degradable, and mechanically tough and strong nacre coating on titanium dental implant by this novel coating technology.     

纯钛种植体表面微弧氧化涂层的生物相容性

背景：各种纯钛种植体表面微弧氧化涂层效果不尽相同。 目的：观察3种不同微弧氧化涂层种植体钛片对小鼠成骨细胞的细胞增殖、碱性磷酸酶活性和β1-integrin的基因表达水平的影响。 方法：采用国际常用小鼠成骨细胞系(MC3T3-E1),3种不同涂层钛片作为影响因素,纯钛作为对照,采用MTT法和电镜法观察细胞附着和细胞增殖,PNPP法测定碱性磷酸酶的活性,RT-PCR法检测β1-integrin在小鼠成骨细胞中的表达。 结果与结论：MTT值、碱性磷酸酶值、β1-integrin的基因表达水平和电镜观察均显示含钙、磷、镁、锌元素的二氧化钛涂层钛片生物相容性最好,含钙磷盐的二氧化钛涂层钛片次之,二氧化钛涂层钛片最差。小鼠成骨细胞在其多孔,含有钙、磷、镁、锌元素表面的黏附及增殖最优。     

Severe wear from retrieved alumina-on-alumina coupled implant: a case report.

This study details the in vivo wear behavior of an alumina acetabular cup and a femoral head on a retrieved non-cemented hip prosthesis. A commercial alumina ceramic-on-ceramic prosthesis was retrieved from a patient previously treated for bilateral hip arthrosis in "coxa profunda". Massive wear was found on the retrieved alumina ceramic head and acetabular cup. The total measured penetration depth was 1.9 mm while the total calculated weight loss for the acetabular cup was 6.06 g. The study underlines the head-cup instability caused by cup loosening as major cause of severe ceramic wear.     

Investigation of titanium leak to bone tissue surrounding dental titanium implant: electron microscopic findings and analysis by electron diffraction

This study investigated the tissue response associated with dental titanium implants. The mandibular third and fourth premolars and first molar of three adult beagle dogs were extracted bilaterally. Healing was then allowed for 3 months. Six titanium implants were placed in the mandibles of a dog. Three weeks after the implantation, mandibular sections containing the implants were retrieved with the use of a bone saw and investigated by light and electron microscopy, X-ray microanalyzer, and electron diffraction. Scanning electron microscopic observation showed titanium particles on the implant-bone interface, and investigation by microanalyzer revealed titanium not only on the implant-bone interface but also in the bone tissue. Transmission electron microscopic observation and investigation by electron diffraction showed titanium in the bone matrix and cells other than macrophages. In this study, titanium particles from the dental implant were recognized morphologically in the surrounding bone tissue. Thus, study of the influence of titanium particles on the human body is needed.     

Effect of UV-photofunctionalization on oral bacterial attachment and biofilm formation to titanium implant material

Bacterial biofilm infections remain prevalent reasons for implant failure. Dental implant placement occurs in the oral environment, which harbors a plethora of biofilm-forming bacteria. Due to its trans-mucosal placement, part of the implant structure is exposed to oral cavity and there is no effective measure to prevent bacterial attachment to implant materials. Here, we demonstrated that UV treatment of titanium immediately prior to use (photofunctionalization) affects the ability of human polymicrobial oral biofilm communities to colonize in the presence of salivary and blood components. UV-treatment of machined titanium transformed the surface from hydrophobic to superhydrophilic. UV-treated surfaces exhibited a significant reduction in bacterial attachment as well as subsequent biofilm formation compared to untreated ones, even though overall bacterial viability was not affected. The function of reducing bacterial colonization was maintained on UV-treated titanium that had been stored in a liquid environment before use. Denaturing gradient gel-electrophoresis (DGGE) and DNA sequencing analyses revealed that while bacterial community profiles appeared different between UV-treated and untreated titanium in the initial attachment phase, this difference vanished as biofilm formation progressed. Our findings confirm that UV-photofunctionalization of titanium has a strong potential to improve outcome of implant placement by creating and maintaining antimicrobial surfaces.     

口腔环境中钛及钛合金腐蚀研究现状

本文介绍了腐蚀学的定义变迁、分类及研究医用金属腐蚀的方法。对钛材料腐蚀原因及口腔介质环境服役中出现腐蚀现象进行了分析 ,得出钛材在口腔服役环境中发生腐蚀与口腔环境介质变化、咀嚼活动参与密切相关。     

Characterization and biocompatibility of a titanium dental implant with a laser irradiated and dual-acid etched surface

The biological properties of commercial pure titanium (cp-Ti) dental implants can be improved by surface treatment. In this study, the cp-Ti surfaces were prepared to enable machined surfaces (TM) to be compared to the machined, sandblasted, laser irradiated and dual-acid etched surfaces (TA). The surface elements and roughness were characterized. The biocompatibility was evaluated by cell and organ culture in vitro. The removal torque was measured in rabbit implantation. Surface characterization revealed that TA surface was more oxidized than TM surface. The TA surface had micrometric, beehive-like coarse concaves. The average roughness (2.28 mum) was larger than that typical of acid-etched surfaces. Extracts of both materials were not cytotoxic to bone cells. The morphology of cells attached on the TA surface was superior to that on the TM surface. TA promoted cell migration and repaired damaged bones more effectively in organ culture. The formation of bone-like nodules on TA disk exceeded that on TM disk. Rabbit tibia implantation also proved that TA implant had greater removal torque value. These results suggested that TA had good osteoconductivity and was a potential material for dental implantation.