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PubMed1995

Effects of particulate high-density polyethylene and titanium alloy on tissue ingrowth into bone harvest chamber in rabbits.

The purpose of this study was to determine whether small, phagocytosable particles of titanium alloy (Ti) and high-density polyethylene (HDPE) have an adverse effect on bone ingrowth. The bone harvest chamber (BHC) was implanted bilaterally in the proximal tibial metaphysis of six mature rabbits. The BHC has a transverse 1-mm wide pore providing a continuous canal through the chamber for tissue ingrowth. After an initial 6-week period for osseointegration of the BHC, the contents of the canal were harvested repeatedly at 3 weekly intervals. This could be done with the chamber in place, without disturbing its exterior surface or the surrounding bone. The carrier solution, 1% sodium hyaluronate (Healon) was implanted first. In subsequent implantations, Healon was mixed with particles of HDPE or Ti averaging 4.7 +/- 2.1 and 3.0 +/- 2.6 microns, respectively. The contralateral chamber was left empty and served as a control. The chambers were harvested repeatedly, alternating experimental and control sides. The sections from the control side, and those containing Healon alone demonstrated extensive trabecular bone in a fibrovascular stroma. The sections containing Ti alloy particles were qualitatively and quantitatively similar to the control sections and those containing Healon, except for the presence of small black granules of Ti alloy, dispersed in the fibrovascular stroma or phagocytosed by scattered macrophages. The sections containing HDPE particles were infiltrated and engulfed by mononuclear and multinuclear histiocytic cells in a highly fibrous stroma. The majority of the multinucleated cells present were interpreted as being foreign body giant cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Alloys↗

PubMed2005

Anodic plasma chemical treatment of titanium Schanz screws reduces pin loosening.

OBJECTIVE: This study was designed to assess the benefits of a new Anodic Plasma Chemical calcium-phosphate (APC-CaP) surface treatment on reducing pin track infection and pin loosening in comparison to anodized titanium (Ti) during external fracture fixation. METHODS: A tibial midshaft, transverse, 6-mm gap osteotomy was created in 17 adult female Swiss alpine sheep. The tibia was stabilized with an external fixator and 4 Schanz screws of Ti or APC-CaP-treated Ti. The sheep were examined during a 12-week observation period. Infection was assessed with weekly clinical pin track grading and microbiologic assessment at sacrifice. Pin loosening was assessed by grading for radiolucency on biweekly radiographs and by measuring extraction torque on pin removal. In vivo bending stiffness measurements were performed to determine gap healing. A qualitative histologic assessment of the tissue adjacent to pin sites was also performed. RESULTS: A trend (P = 0.056) for less infection around APC-CaP pins was found at 6 weeks, but the strength of this difference diminished with time. Significantly more radiolucency was found around Ti pins after 8 (P = 0.011) and 12 (P < 0.001) weeks. At all pin sites, the extraction torque for APC-CaP pins was higher than for Ti pins (P = 0.007). No difference in the progression of gap healing was found. Histology showed bone growth at the implant surface in the form of distance osteogenesis for Ti and contact osteogenesis for APC-CaP. CONCLUSIONS: This study has shown that the APC-CaP surface improves the clinical performance of Ti pins with respect to pin loosening and pin track infection.

Animals↗

PubMed1994

Evaluation of carcinogenicity and chronic toxicity associated with orthopedic implants in mice.

The carcinogenicity and chronic toxicity of 316L stainless steel, nickel, Ti-6A1-4V, hydroxyapatite (HA)-coated Ti-6A1-4V, aluminum oxide containing yttrium oxide, and zirconium oxide containing yttrium oxide were evaluated by implanting solid rods of each material in the thigh muscle of C57BL/6N mice for 24 months. Nickel alloy showed high carcinogenic and toxic potencies, whereas other materials showed no evidence of them. Tumors retaining nickel alloys were malignant fibrous histiocytoma or fibrosarcoma. In some cases, lymphomata that seemed to develop spontaneously were found around the implants because lymphocytes were known to accumulate in chronic inflammatory lesions, and this phenomenon also might be applied to lymphoma.

Alloys↗

PubMed1993

[Nitinol alloy endotracheal stent used in treatment of tracheal stenosis: experimental and clinical applications].

A new method used in treatment of tracheal stenosis by means of nitinol alloy intraluminal tracheal stent (Ni-Ti ITS) is introduced. Altogether 7 stents were implanted into tracheas of 7 mongrels each with a model of tracheal stenosis. The observation periods ranged from 2 to 6 months. The experimental results showed: The Ni-Ti ITSs could maintain long term patency without severe infection or obstruction by granulations or secretion. No displacement was found. There were no signs of either generalized or localized corrosion on the surface of stents. The shape memory character remained unchanged. On the basis of animal experimental study, the stents were successfully used in treatment of 2 patients with tracheal stenosis. One was caused by advanced tracheal tumor, the other was due to recurrent anastomotic stricture.

Adult↗

PubMed1991

[Joint prostheses components of warm-forged and surface treated Ti-6Al-7Nb alloy].

In 1978 development of a TiAl alloy with the inert alloying element niobium was initiated. In 1984, the optimal composition was found to be Ti-6Al-7Nb (Protasul-100). This custom-made alloy for implants has the same alpha/beta micro-structure and equally good mechanical properties as Ti-6Al-4V. The corrosion resistance of Ti-6Al-7Nb is better than that of pure titanium and Ti-6Al-4V, due to the very dense and stable passive layer. Since 1985, highly stressed anchoring stems of various hip prosthesis designs have been manufactured from hot-forged Ti-6Al-7Nb/Protasul-100. Polished surfaces of hip, knee or wrist joints made of Ti-6Al-7Nb intended to articulate with polyethylene are surface-treated by the application of a very hard, 3-5 microns thick titanium nitride coating (Tribosul-TiN), or by oxygen diffusion hardening (Tribosul-ODH) to a depth of 30 microns.

Alloys↗

PubMed2005

An in vitro comparison of implant materials cell attachment, cytokine and osteocalcin production.

Bone deposition, for any implant system, is the deciding factor for the success. The biochemical signals at the cellular level will help elucidate the direction of host response. In this report, intercellular messenger, cytokines, that are regulatory for osteoblast and osteoclast function, were measured. Production of osteocalcin, a marker for osteoblast maturation was also estimated. Human osteoblast-like cells from osteosarcoma cell line MG 63 were grown in wells in the presence of titanium (Ti), titanium alloy (Ti6A14V) and stainless steel implant materials incubated at 37 degrees C. Interleukin-1alpha (IL-1alpha), IL-6, IL-8, IL-11 and osteocalcin were quantitated using standard enzyme linked immunosorbant assay (ELISA) kits from the growth media extracted at specific intervals over the critical ten day period. In all dishes, cells were seen adhering to the base after 24 hours and to confluence at 96 hours. Both IL-1alpha and IL-11 were not produced in sufficient quantities to be measured in the assay (< pg/ml). Interleukin-6 production was significantly higher for stainless steel than for titanium and the alloy. There was a progressive rise in osteocalcin production for titanium contrasted to a basal rate for stainless steel and alloy. Interleukin-8 levels for all metals and controls increased markedly after two days implicating inherent cellular characteristics. A relatively high constant range for macrophage colony stimulating factor from the first day was seen for all metals, including the controls. In conclusion, it appears that titanium implants activate osteocalcin production while stainless steel activates IL-6.

Biocompatible Materials↗

PubMed2004

Effects of Ce on the short-term biocompatibility of Ti-Fe-Mo-Mn-Nb-Zr alloy for dental materials.

Effects of Ce on the short-term biocompatibility of Ti-Fe-Mo-Mn-Nb-Zr alloy designed for implant materials were studied by acute toxicity test, hemolytic test, and MTT assay. The elements and their concentration in surface films and extraction media of Ti alloys were investigated with XPS and ICP, respectively. The primary compositions of the surface films of Ti alloys with 0.3% Ce and without Ce were TiO2 and Nb2O5. There were 0.2 mg/l Fe and 0.16 mg/l Mn in the extraction medium of Ti alloy without Ce, while 0.27 mg/l Fe and 0.87 mg/l Mn in the extraction medium of Ti alloy with 0.3% Ce. The concentrations of Fe and Mn in the medium were too low to have any significant effects on human health. There was no sign of cytotoxicity in these tests. The cytotoxicity levels of Ti alloys without Ce and with 0.3% Ce were graded 0 and 1, respectively. The hemolytic degrees of Ti alloys without Ce and with 0.3% Ce were 0.558% and 0.67%, respectively. The cells being incubated in the extraction medium were normal. These phenomena indicated that Ce was innocuous within the concentration range of this study. In addition, the hemolytic ratio and toxicity level of Ti alloy with 0.3% Ce were a little higher than that of Ti alloy without Ce. This meant that Ce would slightly increase the toxicity of Ti alloy.

Animals↗

PubMed1994

Mixed mode fracture characterization of hydroxylapatite-titanium alloy interface.

Cantilever beam and four-point bend specimen geometries were used to experimentally determine the critical energy release rates for a plasma sprayed hydroxylapatite-titanium alloy (HA-Ti alloy) interface. A locus of energy release rates as a function of crack tip phase angle was determined where a 0 degree phase angle represented tensile opening (mode I) loading and a 90 degree phase angle represented in-plane shear (mode II) loading. Energy release rates were found to increase substantially with an increase in phase angle. An energy release rate of 0.108 N/mm was determined for a phase angle of 0 degrees (mode I). Energy release rates of 0.221, 0.686, and 1.212 N/mm were determined for phase angles of 66 degrees, 69 degrees, and 72 degrees, respectively. The experimental data was matched to a phenomenological model for which crack propagation depended on mode I loading alone indicating that crack propagation at the Ha-Ti alloy interface is dominated by the mode I loading component. Therefore, regions of HA coated implants that experience compressive or shear loading across the HA-Ti alloy interface may be much less likely to debond than regions that experience tensile loading.

Alloys↗

PubMed1993

Post-plasma-spraying heat treatment of the HA coating/Ti-6A1-4V implant system.

The metal/ceramic interface that constitutes an important part of the plasma-sprayed HA-coated Ti-6A1-4V system may, in fact, represent the "weak link" in the implant design. A post-plasma-spray heat treatment to enhance chemical bonding at the metal/ceramic interface and, hence, improve the mechanical properties (interface fracture toughness and tensile coating adhesion strength) of the plasma-sprayed implant system does show promise. In preliminary heat treatment studies, however, any improvements realized were lost due to the chemical instability of the coating in a moisture-laden environment, with a concomitant loss in bonding properties. This deterioration in properties appears to be related to environmentally assisted crack growth as influenced by processing conditions. Still, an ability to improve HA/Ti-6A1-4V bonding through enhanced diffusion bonding was demonstrated, warranting further heat treatment studies involving atmosphere control during processing.

Alloys↗

PubMed2002

In vitro investigation of titanium and hydroxyapatite dental implant surfaces using a rat bone marrow stromal cell culture system.

In this study, rat bone marrow cells (RBM) were used to evaluate different titanium and hydroxyapatite dental implant surfaces. The implant surfaces investigated were: a titanium surface having a porous titanium plasma-sprayed coating (sample code Ti-TPS), a titanium surface with a deep profile structure (sample code Ti-DPS), an uncoated titanium substrate with a machined surface (sample code Ti-ma) and a machined titanium substrate with a porous hydroxyapatite plasma-sprayed coating (sample code Ti-HA). RBM cells were cultured on the disc-shaped test substrates for 14 days. The culture medium was changed daily and examined for calcium and phosphate concentrations. After 14 days specimens were examined by light microscopy, scanning electron microscopy, energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. All test substrates facilitated RBM growth of extracellular matrix formation. Ti-DPS and Ti-TPS to the highest degree, followed by Ti-ma and Ti-HA. Ti-DPS and Ti-TPS displayed the highest cell density and thus seem to be well suited for the endosseous portion of dental implants. RBM cells cultured on Ti-HA showed a delayed growth pattern. This may be related to its high phosphate ion release.

Animals↗

PubMed1990

Surface modification of biomaterials through noble metal ion implantation.

Studies are described involving effects of noble-metal ion implantation on corrosion inhibition and charge-injection capabilities of surgical Ti-6A1-4V alloy. A major factor linked to excellent long-term biological performance is resistance to metal-ion release to tissues. The elements most resistant to corrosion in aqueous solutions are the noble metals. Disadvantages include expense and general inadequacy of mechanical properties. However, if small quantities can be used to surface-modify a surgical device in the last stage of manufacture, that device could possess an optimum combination of environmental integrity, biological response, mechanical properties, and charge-injection capability at minimum expense. Results for ion-implanted Ir are presented. Iridium has been described as the most corrosion-resistant element known, and its activated oxide as having the highest charge-injection capability of any material known. Ti-6A1-4V samples, ion implanted with 2.5 and 5.0 atomic % peak-maximum concentrations of Ir, were subjected to corrosion treatments to enrich the surface with Ir. Corrosion potential and cyclic voltammetry measurements indicated enrichment in H2SO4, and continued enrichment in isotonic saline, with corrosion potentials approaching that of pure Ir, and charge densities in isotonic saline exceeding that of pure Ir for the 5.0% peak-max Ir implanted material. X-ray photoelectron spectroscopy confirmed the high levels of Ir surface enrichment.

Alloys↗

PubMed2004

In situ surface electrochemical characterizations of Ti and Ti-6Al-4V alloy cultured with osteoblast-like cells.

The biocompatibility of metal implants is related to their surface electrochemical characterizations. The in situ growing process of osteoblast-like U-2 OS cells on polished Ti and Ti-6Al-4V alloy during 72h incubation was monitored using the electrochemical impedance spectroscopy (EIS) measurement technique. The results showed that the presence of cells on metals led to an increase in the impedance and polarization resistance (R(p)) of metals. The impedance and R(p) increased as the cells grew (i.e., from adhesion, spreading to proliferation period). A trace amount of V element released from Ti-6Al-4V alloy led to a lower R(p) with respect to Ti metal during cell culture. In this study, a satisfactory equivalent circuit simulating the electrochemical characterizations of Ti and Ti-6Al-4V alloy cultured with cells was proposed. The EIS measurement technique was applied successfully to monitor the in situ growing process of U-2 OS cells on Ti and Ti-6Al-4V alloy.

Alloys↗

PubMed1993

Histological and histomorphometrical evaluation of the bone reaction to three different titanium alloy and hydroxyapatite coated implants.

The aim of this study was to investigate the bone response to three different types of titanium (Ti) alloys and hydroxyapatite (HA) coated titanium alloy by histological and histomorphometrical analysis. Therefore, implants made of these materials were inserted into the tibia of rabbits. Implantation times were 6 and 16 weeks. The histological evaluation included measurement of the amount of bone apposition and analysis of the bone reaction and interface characteristics around the implants. The results demonstrated no marked differences in bony reaction to the different implant materials. In addition, the HA coatings showed loss of thickness.

Bone Remodeling↗

PubMed2000

The effect of osteopenia on the osteointegration of different biomaterials: histomorphometric study in rats.

The osteointegration of Hydroxyapatite (HA), Titanium (Ti-6Al-4V: Ti), Zirconia (ZrO2), Alumina (Al2O3) and 2 biological glasses (AP40 and RKKP) was comparatively investigated in normal and osteopenic rats by means of histomorphometry. Thirty-six Sprague Dawley female rats were left intact (Group C) while 36 were ovariectomized (Group OVX). Group C and OVX were further divided into 6 subgroups. After 16 weeks all animals were submitted to the femoral implant of nails made of the above-mentioned materials. Eight weeks after implantation the animals were euthanized, the femurs were harvested for histomorphometric analysis. The data showed that: (1) all the tested materials were biocompatible in vitro; (2) no significant differences existed in Affinity Index (AI) of Group C; and (3) results from paired comparison applied to the AI showed significant differences among the Groups C and OVX. The AI did not significantly change among intact groups, while it significantly decreased when some materials were implanted in OVX subgroups (AP40, ZrO2 and Ti-6Al-4V: p < 0.0005, p < 0.05 and p < 0.01). It is confirmed that bone mineral density is a strong predictor of the osteointegration of an orthopedic implant and that the use of pathological animal models is necessary to completely characterize biomaterials.

Journal Article↗

PubMed1994

An evaluation of electrodischarged prototype implants in rabbit tibia: a preliminary study.

This is the first in a series of biological investigations using a porous implant fabricated by a novel process known as electrodischarge compaction (EDC). This process uses Ti-6A1-4V powder and electrical energy to construct a beaded porous implant without any compromise in physical characteristics, often found with conventional sintering. The purpose of this study was to evaluate the bone response in rabbit tibia of a porous titanium prototype implant fabricated by this new technique. One hundred forty-four porous EDC-fabricated implants were placed into the tibia of 36 New Zealand rabbits. Animals were placed into one of six time periods (2, 4, 8, 12, 18, and 24 weeks). At the appropriate time period, animals were killed, and bone ingrowth was evaluated qualitatively by light and scanning electron microscopy. Bone/implant interface bond strength was also measured. Slight bone ingrowth was observed as early as the two-week time period and increased in depth at each time period for the duration of the study. Implant/bone bond strength was measurable at four weeks and continued until reaching a plateau at week 12. The results of this study suggest that this novel EDC implant may be suitable for continued development of an easily fabricated, cost-effective dental implant.

Aluminum↗

PubMed2006

[In vivo and in vitro studies on anode-oxidized titanium percutaneous implants].

In order to solve the problesm in biological sealing of load-bearing percutaneous implants for a fairly long time, we investigated titanium with bioactivated anodic oxidized surface(group A) through the animal tests in vivo and the epithelium cell culture in vitro. Smooth Ti (group B) was used as control. The animal tests results showed that there was no evident difference in the inflammory reaction between the group A implant tissues and the group B implant/tissues. The bioactivated Ti surface could keep the implant not only bonding with the bone firmly but also adhering to the soft tissue closely, thus contributing to the formation of calcium phosphate layer and its micropores. The cell culture results also demonstrated that the microporous surface of group A could clasp and fix the skin. So, it can be concluded that the surface modified method of anode oxidization may be one of the most effective methods to resolve the problem of durable biological sealing.

Animals↗

PubMed2001

Combustion synthesis of porous materials for bone replacement.

Production of highly porous composite materials by traditional materials processing is limited by difficult processing techniques. However, combustion or self-propagating high-temperature synthesis (SHS) allows many porous ceramic, intermetallic, glass, and metallic systems to be formed with relative ease. Examination of the SHS reaction parameters that control the extent of porosity further increases the feasibility of producing novel composites for such uses as bone implant applications. Combustion Synthesis of porous Ti-TiBx and NiTi composite materials have been studied with respect to the sensitivity to the SHS reaction parameters of stoichiometry, green density, gasifying agents, and gravity. The main objective of this research program is to engineer the required porosity and mechanical properties into the composite materials to meet the requirements of a consumer, such as for the application of bone replacement materials. Biomedical results indicated strongly that there is natural bone ingrowth with no apparent immune response in the composite materials produced by this process.

Alloys↗

PubMed2002

Investigation on plasma immersion ion implantation treated medical implants.

In this work the biocompatibility of osteosynsthesis plates treated with plasma immersion ion implantation (PIII) was tested using a rat model. Small rods (Ø 0.9 mm, and length 10 mm) prepared from different materials-pure Ti, anodised Ti, and two NiTi alloys (SE 508, and SM 495)-were implanted with oxygen by PIII to form a rutile surface layer and subsequently inserted into rat femurs, together with a control group of untreated samples. The results of the biomechanical tests correlate with the histological results, and show that plasma immersion ion implantation leads to an increase of biocompatibility and osseointegration of titanium and NiTi, albeit no improvement of the (bad) biocompatibility of the anodised Ti. Despite the layer thickness of up to 0.5 microm a strong influence of the base material is still present.

Animals↗