Porous Titanium Surface Research Articles

Titanium induces pro-inflammatory and tissue-destructive responses in primary human macrophages.

Implants and medical devices are efficient and practical therapeutic solutions for a multitude of pathologies. Titanium and titanium alloys are used in orthopedics, dentistry, and cardiology. Despite very good mechanical properties, and corrosion resistance titanium implants can fail due to inflammatory or tissue-degradation related complications. Macrophages are major immune cells that control acceptance of failure of the implant. In this study, for the first time, we have performed a systematic analysis of the response of differentially activated human macrophages (M(Control), M(IFNγ) and M(IL-4)) to the polished and porous titanium surfaces in order to identify the detrimental effect of titanium leading to the tissue destruction and chronic inflammation. Transcriptome analysis revealed that the highest number of differences between titanium and control settings are found in M(IL-4) that model healing type of macrophages. RT-qPCR analysis confirmed that both polished and porous titanium affected expression of cytokines, chitinases/chitinase-like proteins and matrix metalloproteinases. Titanium-induced release and activation of MMP7 by macrophages was enhanced by fibroblasts in both juxtacrine and paracrine cell interaction models. Production of titanium-induced MMPs and cytokines associated with chronic inflammation were independent of the presence of Staphylococcus aureus. MMP7, one of the most pronounced tissue-destroying factor and chitinase-like protein YKL-40 were expressed in CD68+ macrophages in peri-implant tissues of patients with orthopedic implants. In summary, we demonstrated that titanium induces pro-inflammatory and tissue-destructing responses mainly in healing macrophages, and the detrimental effects of titanium surfaces on implant-adjacent macrophages are independent on the bacterial contamination.

A novel porous titanium with engineered surface for bone defect repair in load-bearing position.

Porous titanium exhibits low elastic modulus and porous structure is thought to be a promising implant in bone defect repair. However, the bioinert and low mechanical strength of porous titanium have limited its clinical application, especially in load-bearing bone defect repair. Our previous study has reported an infiltration casting and acid corrosion (IC-AC) method to fabricate a novel porous titanium (pTi) with 40% porosity and 0.4 mm pore diameter, which exerts mechanical property matching with cortical bone and interconnected channels. In this study, we introduced a nanoporous coating and incorporated an osteogenic element strontium (Sr) on the surface of porous titanium (named as Sr-micro arch oxidation [MAO]) to improve the osteogenic ability of the pTi by MAO. Better biocompatibility of Sr-MAO was verified by cell adhesion experiment and cell counting kit-8 (CCK-8) test. The in vitro osteogenic-related tests such as immunofluorescence staining, alkaline phosphatase staining and real-time polymerase chain reaction (RT-PCR) demonstrated better osteogenic ability of Sr-MAO. Femoral bone defect repair model was employed to evaluate the osseointegration of samples in vivo. Results of micro-CT scanning, sequential fluorochrome labeling and Van Gieson staining suggested that Sr-MAO showed better in vivo osteogenic ability than other groups. Taking results of both in vitro and in vivo experiment together, this study indicated the Sr-MAO porous titanium could be a promising implant load-bearing bone defect.

Clinical evaluation of the three-dimensional printed strut-type prosthesis combined with autograft reconstruction for giant cell tumor of the distal femur.

This study aimed to describe the design and surgical techniques of a three-dimensional (3D) printed strut-type prosthesis with a porous titanium surface for distal femur giant cell tumors of bone (GCTB) and evaluate the short-term clinical outcomes. From June 2018 to January 2021, 9 consecutive patients with grade I or II GCTB in the distal femur underwent extended intralesional curettage followed by 3D-printed strut-type prosthesis combined with autograft reconstruction were retrospectively reviewed to assess their clinical and radiographic outcomes. All patients were followed up for 30.8 ± 7.5 months (18-42 months) after surgery. The mean affected subchondral bone percentage and the mean subchondral bone thickness before surgery was 31.8% ± 9.6% (range, 18.2% ~50.2%) and 2.2 ± 0.8mm (range, 1.2-4.0mm), respectively. At the final follow-up, all the patients were alive without local recurrence; no postoperative complications were observed. Patients had significant improvements in postoperative MSTS-93 score [(26.7 ± 2.4) vs. (18.8 ± 3.7), P < 0.05], and ROM [(122.8° ± 9.1°) vs. (108.3° ± 6.1°), P < 0.05] compared with their preoperative statuses. Furthermore, the mean subchondral bone thickness has increased to 10.9 ± 1.3mm (range, 9.1-12.1mm). 3D-printed strut-type prosthesis combined with autograft reconstruction provides acceptable early functional and radiographic outcomes in patients with grade I or II GCTB in distal femur due to the advantages of the prosthesis such as good biocompatibility, osseointegration capacity, and subchondral bone protection. If our early outcomes can be further validated in studies with more patients and sufficient follow-up, this method may be evaluated as an alternative for the treatment of grade I or II GCTB in the distal femur.

COMPARATIVE SURVIVAL OF CONTEMPORARY CEMENTLESS ACETABULAR COMPONENTS FOLLOWING PRIMARY TOTAL HIP ARTHROPLASTY

The last two decades have seen remarkable technological advances in total hip arthroplasty (THA) implant design. Porous ingrowth surfaces and highly crosslinked polyethylene (HXLPE) have been expected to dramatically improve implant survivorship. The purpose of the present study was to evaluate survival of contemporary cementless acetabular components following primary THA.16,421 primary THAs performed for osteoarthritis between 2000 and 2019 were identified from our institutional total joint registry. Patients received one of 12 contemporary cementless acetabular designs with HXLPE liners. Components were grouped based on ingrowth surface into 4 categories: porous titanium (n=10,952, mean follow-up 5 years), porous tantalum (n=1223, mean follow-up 5 years), metal mesh (n=2680, mean follow-up 6.5 years), and hydroxyapatite (HA) coated (n=1566, mean follow-up 2.4 years). Kaplan-Meier analyses were performed to assess the survivorship free of acetabular revision. A historical series of 182 Harris-Galante-1 (HG-1) acetabular components was used as reference.The 15-year survivorship free of acetabular revision was &gt;97% for all 4 contemporary cohorts. Compared to historical control, porous titanium (HR 0.06, 95% CI 0.02–0.17, p&lt;0.001), porous tantalum (HR 0.09, 95%CI 0.03–0.29, p&lt;0.001), metal mesh (HR 0.11, 95%CI 0.04–0.31, p&lt;0.001), and HA-coated (HR 0.14, 95%CI 0.04–0.48, p=0.002) ingrowth surfaces had significantly lower risk of any acetabular revision. There were 16 cases (0.1%) of acetabular aseptic loosening that occurred in 8 (0.07%) porous titanium, 5 (0.2%) metal mesh, and 3 (0.2%) HA-coated acetabular components. 7 of the 8 porous titanium aseptic loosening cases occurred in one known problematic design. There were no cases of aseptic loosening in the porous tantalum group.Modern acetabular ingrowth surfaces and HXLPE liners have improved on historical results at the mid-term. Contemporary designs have extraordinarily high revision-free survivorship, and aseptic loosening is now a rare complication.At mid-term follow-up, survivorship of contemporary uncemented acetabular components is excellent and aseptic loosening occurs in a very small minority of patients.

Built-up sodium alginate/chlorhexidine multilayer coating on dental implants with initiating anti-infection and cyto-compatibility sequentially for soft-tissue sealing

Soft-tissue sealing at transmucosal sites is very important for preventing the invasion of pathogens and maintaining the long-term stability and function of dental implants. However, the colonization of oral pathogens on the implant surface and surrounding soft tissues can disturb the early establishment of soft-tissue sealing and even induce peri-implant infection. The purpose of this study was to construct two antibacterial coatings with 5 or 10 sodium alginate/chlorhexidine bilayers on titanium surfaces using layer-by-layer self-assembly technology to promote soft-tissue sealing. The corresponding chemical composition, surface topography, wettability and release behaviour were investigated to prove that the resultant coating of sodium alginate and chlorhexidine was coated on the porous titanium surface. In-vitro and in-vivo antibacterial results showed that both prepared coatings inhibited or killed the bacteria on their surfaces and the surrounding areas to prevent plaque biofilm formation, especially the coating with 10 bilayers. Although both coatings inhibited the initial adhesion of fibroblasts, the cytocompatibility gradually improved with coating degradation. More importantly, both coatings achieved cell adhesion and proliferation in an in-vitro bacterial environment and effectively alleviated bacteria-induced subcutaneous inflammation in-vivo. Therefore, this study demonstrated that the multilayered coating could prevent implant-related infections in the initial stage of implant surgery and then improve soft-tissue integration with implant devices.

Enhancement of In Vitro Bioactivity of One-Step Spark Plasma Sintered Porous Titanium by Alkali-Treatment

Bioactivity and stress shielding are the most important problems of medical implanted porous titanium. In this study, porous titanium with 40% porosity was prepared by one-step spark plasma sintered (SPS) technology, and the surface of porous titanium was modified by a simplified alkali treatment method. The effects of a high concentration on pore properties, mechanical properties, and biological activities of porous titanium were investigated. The results show that the surface of porous titanium treated with a high concentration of alkali forms an interconnected network layer, which provides nucleation points for the formation of apatite. Porous titanium can still meet the requirements of hard tissue replacement after treatment with high-concentration alkali solution (yield strength (130 MPa) and elastic modulus (6.0 GPa)). A layer of apatite is formed on the surface of porous titanium after alkali treatment. The ability of inducing apatite formation increases with the increase of lye concentration. In addition, the results of proliferation and live dead cell staining of bone mesenchymal stem cells (BMSC) showed that alkali treatment had no toxic effect on the cells. With the increase of concentration, the cell activity was significantly enhanced. Therefore, the bioactive porous titanium modified with simplified alkali has a good medical prospect as artificial bone material.

Osseointegration of 3D-printed titanium implants with surface and structure modifications

BackgroundThe purpose of this study was to establish a mechanical and histological basis for the development of biocompatible maxillofacial reconstruction implants by combining 3D-printed porous titanium structures and surface treatment. Improved osseointegration of 3D-printed titanium implants for reconstruction of maxillofacial segmental bone defect could be advantageous in not only quick osseointegration into the bone tissue but also in stabilizing the reconstruction. MethodsVarious macro-mesh titanium scaffolds were fabricated by 3D-printing. Human mesenchymal stem cells were used for cell attachment and proliferation assays. Osteogenic differentiation was confirmed by quantitative polymerase chain reaction analysis. The osseointegration rate was measured using micro computed tomography imaging and histological analysis. ResultsIn three dimensional-printed scaffold, globular microparticle shape was observed regardless of structure or surface modification. Cell attachment and proliferation rates increased according to the internal mesh structure and surface modification. However, osteogenic differentiation in vitro and osseointegration in vivo revealed that non-mesh structure/non-surface modified scaffolds showed the most appropriate treatment effect. Conclusion3D-printed solid structure is the most suitable option for maxillofacial reconstruction. Various mesh structures reduced osteogenesis of the mesenchymal stem cells and osseointegration compared with that by the solid structure. Surface modification by microarc oxidation induced cell proliferation and increased the expression of some osteogenic genes partially; however, most of the markers revealed that the non-anodized solid scaffold was the most suitable for maxillofacial reconstruction.

Functionalization with Polyphenols of a Nano-Textured Ti Surface through a High-Amino Acid Medium: A Chemical-Physical and Biological Characterization.

The study aimed to identify an effective mechanism of adsorption of polyphenols on a nano-textured Ti surface and to evaluate the osteogenic differentiation on it. The source of polyphenols was a natural extract from red grape pomace. A chemical etching was used to form an oxide layer with a nanoscale texture on Ti; this layer is hydrophilic, but without hydroxyl groups with high acidic–basic chemical reactivity. The samples were characterized by electron and fluorescence microscopies, UV–Vis spectroscopy, contact angle measurements, zeta potential titration curves, and Folin–Ciocâlteu test. The presence of an adsorbed layer of polyphenols on the functionalized surface, maintaining redox ability, was confirmed by several tests. Consistent with the surface features, the adsorption was maximized by dissolving the extract in a high–amino acid medium, with respect to an inorganic solution, exploiting the high affinity of amino acids for polyphenols and for porous titanium surfaces. The osteogenic differentiation was assessed on an osteoblastic cell line by immunofluorescence, cell viability, expression of key osteoblast markers, and extracellular matrix mineralization. The surfaces functionalized with the extract diluted in the range 1 × 10−5–1 mg/mL resulted in having a greater osteogenic activity for the highest concentration, with lower values of cell viability; higher expression of alkaline phosphatase, bone sialoprotein, and collagen; and lower levels of osteopontin. In conclusion, the functionalization of a nano-textured Ti surface with polyphenols can potentially favor the osteogenic activity of osseointegrated implants.

Enhancing antibacterial property of porous titanium surfaces with silver nanoparticles coatings via electron-beam evaporation

Antibacterial activity is one of the most vital characteristics for Titanium (Ti) dental implants. Coating antibacterial material onto Ti surfaces is an effective approach to enhance their intrinsic antibacterial ability. However, a cost-effective but efficient coating strategy for realizing this objective still remains challenging. In this study, we proposed a novel implant surface modification strategy for coating silver nanoparticles onto the porous Ti surface via a facile electron beam evaporation (EBE) approach. Porous Ti surfaces were firstly prepared by sand-blasting large grit acid-etching (SLA) process. Then, the silver nanoparticles coating thickness on the porous Ti surface was adjusted and optimized by altering the duration of EBE process. Consequently, composite porous Ti surfaces with different silver thicknesses were synthesized. Polished Ti (PT) surface without SLA or EBE process was also prepared as the controlled blank group. The surface characterizations were analyzed by SEM, AFM, and XPS. After that, the antibacterial properties of all groups were tested with bacteria counting method, bacterial viability test, live/dead bacterial staining, and SEM examination. Results show that silver nanoparticles were uniformly distributed on the porous Ti surfaces after the SLA and EBE processes. After being incorporated with silver nanoparticles, the composite surfaces successfully inhibited the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antibacterial ratio (AR) values of SLA-Ag groups increased with the increasing silver thickness and are significantly higher than those of PT and SLA groups. Therefore, by the SLA and EBE processes, the composite porous Ti surfaces modified with silver nanoparticles coatings demonstrate superior antibacterial property compared with pure Ti surfaces, which is highly promising for enhancing the antibacterial functions of dental implants.Graphical abstract

Effects of Titanium Implant Surface Topology on Bone Cell Attachment and Proliferation in vitro.

PurposeTitanium is commonly used for implants because of its corrosion resistance and osseointegration capability. It is well known that surface topology affects the response of bone tissue towards implants. In vivo studies have shown that in weeks or months, bone tissue bonds more efficiently to titanium implants with rough surfaces compared to smooth surfaces. In addition, stimulating early endosseous integration increases the long-term stability of bone-implants and hence their clinical outcome. Here, we evaluated the response of human MG-63 osteoblast-like cells to flat and solid, compared to rough and porous surface topologies in vitro 1–6 days post seeding. We compared the morphology, proliferation, and attachment of cells onto three smooth surfaces: tissue culture (TC) plastic or microscope cover glasses, machined polyether-ether-ketone (PEEK), and machined solid titanium, to cells on a highly porous (average Ra 22.94 μm) plasma-sprayed titanium surface (composite Ti-PEEK spine implants).MethodsWe used immuno-fluorescence (IF) and scanning electron microscopy (SEM), as well as Live/Dead and WST-1 cell proliferation assays.ResultsSEM analyses confirmed the rough topology of the titanium implant surface, compared to the smooth surface of PEEK, solid titanium, TC plastic and cover glasses. In addition, SEM analyses revealed that MG-63 cells seeded onto smooth surfaces (solid titanium, PEEK) adopted a flat, planar morphology, while cells on the rough titanium surface adopted an elongated morphology with numerous filopodial and lamellipodial extensions interacting with the substrate. Finally, IF analyses of focal adhesions (vinculin, focal adhesion kinase), as well as proliferation assays indicate that MG-63 cells adhere less and proliferate at a slower rate on the rough than on a smooth titanium surface.ConclusionThese observations suggest that bone-forming osteoblasts adhere less strongly and proliferate slower on rough compared to smooth titanium surfaces, likely promoting cell differentiation, which is in agreement with other porous implant materials.

Improvement of polydopamine-loaded salidroside on osseointegration of titanium implants

BackgroundMicroarc oxidation (MAO) on the surface of medical pure titanium can improve its histocompatibility, and loading drugs on the surface can resist excessive intimal hyperplasia.MethodsIn this study, salidroside (SAL) was loaded on the surface of porous titanium (Ti) with polydopamine (PDA) carrier. The effects of SAL on the osteogenesis and angiogenesis of Ti implants were studied by phalloidin staining, alizarin red staining, ALP staining, wound-healing assay, cell transwell assay, matrigel tube formation, and osteogenic and angiogenic genes and proteins expression detected by PCR and western blot in vitro. The bone defect model experiments in rats was established in vivo including X-ray, micro CT, hematoxylin and eosin staining (HE), immunohistochemistry (IHC), Goldner's trichrome analysis, Safranin O-fast green staining and determination of contents of TNF-α and IL-6 in serum.ResultsEDS and EDS mapping showed that SAL could be loaded on the surface of the MAO coating by PDA. A drug release experiment showed that SAL loaded on the Ti coating could release slowly and stably without sudden release risk. In vitro cell experiments showed that the SAL coating could promote the proliferation, morphology, calcification and alkaline phosphate activity of MC3T3-E1 cells. At the same time, it promoted the migration and tube formation of HUVEC cells. The SAL coating promoted osteogenesis and angiogenesis by promoting the expression of genes and proteins related to. In vivo experiments, HE and IHC showed that SAL significantly promoted the expression of COL-1 and CD31. Goldner's trichrome and Safranin O-fast green staining showed that SAL coating could increase the new bone tissue around the implantation site. The SAL coating had anti-inflammatory activity by reducing the levels of TNF-α and IL-6 in vivo.ConclusionTherefore, SAL could improve osteogenesis and angiogenesis in conjunction with the Ti-PDA coating.

Modification of Titanium Surface by Ion Implantation

The article considers a method for obtaining deuterium storage on titanium samples. The depth of penetration of deuterium ions into the outer surface of porous titanium is calculated by increasing the resistance of the samples. Higher resistance of the samples is shown to be caused by the creation of a dielectric layer of titanium deuteride on the surface. It was proven that the depth of penetration of deuterium ions into the surfaces of the samples is significantly greater than the classical concept about the doping process explains. The design of an ion doping unit contains a vacuum working chamber with a working table for placing samples. The ion beam comes from an ion source in crossed electric and magnetic fields of the Penning type. The working gas of the ion source is deuterium. The ion source gas is supplied through a special fitting in the design of the ion source, connected to the deuterium cylinder through a special leak. The working chamber is pumped out by a high-vacuum unit, to which a pre-vacuum pump is connected at the outlet. The ion implantation unit is electrically powered from three power sources. A power supply with a voltage of up to 5 [kV] and a current of up to 100 [mA] feeds the gas discharge of the source. The 10 [kV] power supply gives a negative potential to the target, and deuterium ions coming out of the hole in the cathode of the ion source are accelerated towards the desktop with the power supply up to 40 [kV] and up to 10 [ma].

A chemical patterning approach of dense and porous titanium surfaces by using a combination of concentrated acid and oxidant

Commercially dense pure titanium sheets and porous titanium samples processed by powder metallurgy were treated with a mixture consisting of equal volumes of H2SO4 and H2O2 for 2 or 4 hours. Characterization was performed by scanning electron microscopy, energy dispersive X-ray spectroscopy, confocal scanning optical microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The analyses showed that the chemical patterning approach using a combination of concentrated acid and oxidant was able to generate a nanotexture on dense and porous titanium surfaces. In addition, the treated samples presented an oxide layer consisting predominantly of titanium dioxide with negative charge conferred by the presence of hydroxyl groups, which is an important factor that favors apatite nucleation and protein adsorption. It was also observed that oxide formation was more effective on porous samples than on dense samples, which can be explained by the higher surface area intrinsic to porous media. Finally, the findings indicated that both treatment times promoted similar modifications in surface properties, such as nanotexture and chemical composition, suggesting that the time of 2 hours were enough to induce the surface alterations at the nanoscale.

A multifunctional silk coating on additively manufactured porous titanium to prevent implant-associated infection and stimulate bone regeneration

Despite tremendous progress in the design and manufacturing of metallic implants, they do not outlive the patient. To illustrate, more than half of hip replacements will fail, mainly due to implant infection and loosening. Surface engineering approaches and, in particular, coatings can facilitate implant bio-functionality via the recruitment of more host cells for new bone formation and inhibition of bacterial colonization. Here, we used electrophoretic deposition to apply a silk fibroin solution consisting of tricalcium phosphate (TCP) and vancomycin as a coating on the surface of additively-manufactured porous titanium. Furthermore, the surface properties of the coatings developed and the release kinetics of the vancomycin were studied to evaluate the applied coating. The in vitro antibacterial behavior of the multifunctional coating, as well as the cell viability and osteogenic differentiation of the MC3T3-E1 cell line were extensively studied. The biomaterials developed exhibited an antibacterial behavior with a reduction of up to four orders of magnitude in both planktonic and adherent bacteria for 6 h and 1 d. A live-dead assay, the Alamar Blue activity, the DNA content, and cytoskeleton staining demonstrated a significant increase in the cell density of the coated groups versus the as-manufactured ones. The significantly enhanced calcium deposition and the increase in mineralization for the groups with TCP after 21 and 28 d, respectively, demonstrate upregulation of the MC3T3 cells’ osteogenic differentiation. Our results collectively show that the multifunctional coating studied here can be potentially used to develop a new generation of orthopedic implants.

Poly-l-lysine/Sodium Alginate Coating Loading Nanosilver for Improving the Antibacterial Effect and Inducing Mineralization of Dental Implants.

In recent years, antibacterial surface modification of titanium (Ti) implants has been widely studied in preventing implant-associated infection for dental and orthopedic applications. The purpose of this study was to prepare a composite coating on a porous titanium surface for infection prevention and inducing mineralization, which was initialized by deposition of a poly-l-lysine (PLL)/sodium alginate(SA)/PLL self-assembled coating, followed by dopamine deposition, and finally in situ reduction of silver nanoparticles (AgNPs) by dopamine. The surface zeta potential, SEM, XPS, UV–vis, and water contact angle analyses demonstrate that each coating was successfully prepared after the respective steps and that the average sizes of AgNPs were 20–30 nm. The composite coating maintained Ag+ release for more than 27 days in PBS and induced mineralization when incubated in SBF. The antibacterial results showed that the composite coating inhibited/killed bacteria on the material surface and killed bacteria around them. In addition, although this coating inhibited the initial adhesion of osteoblasts, the mineralized surface greatly enhanced the cytocompatibility. Thus, we concluded that the composite coating could prevent bacterial infections and facilitate mineralization in vivo in the early postoperative period, and then, the mineralized surface could enhance the cytocompatibility.

Construction and Biological Performance of Porous Titanium Surface Nanotube Arrays

TiO₂ nanotube array films were prepared on porous titanium via anodic oxidation. The morphology and phases of the films were characterized, and the thermal stability, bioactivity <em>In-vitro</em>, biocompatibility <em>in vivo</em>, and osteoinductivity of the films were also studied. It was found the anatase nanotubues give better bioactivity than the amorphous.

Enhancement of mineralization on porous titanium surface by filling with nano-hydroxyapatite particles fabricated with a vacuum spray method.

Nano-hydroxyapatite (nano-HA) coating has been proved to be effective to modify the titanium surface for better bone formation. A simple and economical nano-HA coating method that filling the nano-HA particles into the porous titanium substrate by using vacuum suction was introduced in this study. Two kinds of nano-HA modified titanium surfaces, nano-HA filled type (nHA-f) and nano-HA coated type (nHA-c), were prepared by a 2-step and 3-step protocol, respectively. Nano-HA modified titanium surfaces with and without thermal treatment were compared. The physicochemical properties including morphology, elemental composition, coating thickness, adhesion strength and in vitro mineralization ability were characterized. The SEM results showed that nano-HA particles were effectively filled into the porous titanium substrate under the function of vacuum suction in the nHA-f and nHA-f-heat groups. The thickness of the nano-HA layer was about 1μm and 7-8μm in the nano-HA filled type and nano-HA coating type, respectively. Localized separation between the nano-HA layer and the titanium substrate was observed in the thermal-treated groups, which may increase the risks of detachment. In the in vitro mineralization test, the unheated groups (nHA-f and nHA-c) showed promoted calcium phosphate compounds deposition than the heated groups (nHA-f-heated and nHA-c-heated) because of the active biological behavior of the amorphous nano-HA; the nHA-f group with a thin nano-HA layer showed no difference to the thick coating group (nHA-c) at the early stage, which was due to the effect of the porous structure as a cage to protect the nano-HA particles from fast dissolution. In conclusion, the vacuum spray method is effective to create a thin amorphous nano-HA layer with improved adhesion strength and sustained-release ability to induce mineralization by filling the nano-HA particles into the porous titanium substrate without thermal treatment.

Chlorhexidine-grafted coating to improve antibacterial property of the micro/nanoporous titanium surfaces

Objective: To investigate the antibacterial properties and the osteoblast-compatibility of chlorhexidine (CHX)-modified porous titanium. Methods: Smooth pure titanium specimen with diameter of 10.0 mm and thickness of 1.5 mm treated with alkali heat method were set as control group. Those with covalent conjugation of aminosilane were set as silane group, and those with CHX grafted by glutaraldehyde were set as CHX group. Scanning electron microscope (SEM) was used to observe the surface morphology and element compositions were detected by X-ray photoelectron spectroscopy. Hydrophilicity was analyzed by surface water contact angle test (n=6), while surface amino/imine groups quantification were performed through acid orangeⅡ(n=5) and the CHX was quantified by optical densitometric method (n=5). Live/dead bacterial staining, the morphology of adherent bacteria by SEM, plate counting method and inhibition zone method were executed to evaluate the antibacterial property of the samples. Osteoblast compatibility was evaluated by methyl thiazolyl tetrazolium. Cell-bacterial co-culture was conducted to evaluated the cell viability on the samples under the circumstance with bacteria. Results: After CHX grafting, pores on the titanium surface were decreased, while the atom ratio of C, N, Cl increased and the water contact angle decreased to 37.5°±4.0°. The density of CHX on the surface was (5.07±0.39) μg/cm(2). The results of live/dead bacterial staining and the morphology of adherent bacteria showed that only little dead bacterial (bacterial wall rupture) adherent on the surface of CHX group, which proved that the modified surface could inhibit bacteria adhesion and even destroyed bacteria; the plate counting displayed sporadic colonies and a transparent inhibition zone could be observed, which demonstrated that CHX group could suppress bacteria multiplication from surrounding environment. When incubating for 1 and 3 days, the cell viability of CHX group showed no significant difference from that of control group (P>0.05) ; when incubating for 5 days, the value of cell viability of CHX group was 0.547±0.087, and this was significantly lower than that of the control group (0.751±0.056) (P<0.05), demonstrating a slight inhibition of cell proliferation by CHX. The results of bacteria-cell co-culture for 3 days showed that a mass of bacteria adhered on the surface of the control group while considerable cells adhered on the surface of CHX group and exhibited a good shape. Conclusions: Porous titanium surface grafted by CHX showed an excellent antibacterial properties and allowed cell adhesion in bacterial circumstance, providing immediate implantation options for patients with bad oral health.

Effect of SBF on Cyclic Compression Behaviour of Porous Titanium Component for Implant Application

In the recent years, porous structure is being drawn attention to the researcher for implant application for superior characteristics over bulk materials. The aim of this study is to evaluate the cyclic compression behaviour of porous titanium components in simulated body fluid (SBF). Porous titanium component developed by replica impregnation method was taken for study. Compression tests in air revealed that the yield strength of the porous body is 8MPa on average and elastic modulus is around 180MPa which is compatible to cancellous bone application. After 10% strain porous structure deformed plastically producing a long plateau region. Compressive fatigue tests revealed that at higher stress level porous titanium failed earlier in SBF than in air. In contrast, fatigue limit of porous substrate is 2 MPa which was not affected by SBF medium. After 10 million cycles in SBF, Calcium Phosphate layer was partially formed on the surface of porous titanium by re-precipitation from SBF. EDS analysis showed that the Ca/P atomic ratio was 1.44 which is near to beta TCP and HA phase and these phases are beneficial for bone tissue ingrowth.

The Use of Porous Titanium Coating and the Largest Possible Head Do Not Affect Early Cup Fixation: A 2-Year Report from a Randomized Controlled Trial.

Background:Cups are more frequently revised than stems after uncemented total hip arthroplasty, which warrants the development of cup surfaces that provide long-lasting, stable fixation. Large heads have become popular with the aim of reducing dislocation rates, but they generate greater frictional torque that may compromise cup fixation. We aimed to investigate (1) if a novel porous titanium surface provides superior cup fixation when compared with a porous plasma spray (PPS) surface and (2) if the use of the largest possible head compromises cup fixation when compared with a 32-mm head.Methods:Ninety-six patients were randomized to receive either a cup with a porous titanium coating (PTC) or a cup with PPS. A second randomization was performed to either the largest possible (36 to 44-mm) or a 32-mm head in metal-on-vitamin-E-infused polyethylene bearings. Roentgen stereophotogrammetric analysis (RSA) examinations were obtained postoperatively at 3, 12, and 24 months. The primary outcome was proximal cup migration when comparing the 2 cup surfaces and also when comparing the largest possible head with the 32-mm head. The patients were followed for 2 years.Results:The median (and interquartile range) proximal cup migration was 0.15 mm (0.02 to 0.32 mm) for the PTC cup and 0.21 mm (0.11 to 0.34 mm) for the PPS cup. The largest possible head had a proximal cup migration of 0.15 mm (0.09 to 0.31 mm), and the 32-mm head had a proximal cup migration of 0.20 mm (0.04 to 0.35 mm). There were no significant differences between the cup surface (p = 0.378) or the head size (p = 0.693) groups.Conclusions:Early cup fixation was not superior with the novel PTC cup; the use of the largest possible head (36 to 44 mm) did not compromise early cup fixation.Level of Evidence:Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.