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PubMed1985

Functional tricuspid insufficiency: conservative or operative management.

Between 1978 and 1982 mitral valve replacement was performed in a total of 43 patients with mitral valve disease in the presence of functional tricuspid insufficiency (TI). The concomitant tricuspid valve regurgitation was treated conservatively in 17 patients, a Carpentier ring prosthesis was implanted in 9 patients. De Vega annuloplasty was performed in 13 patients and 4 times the valve was replaced with a Hancock bioprosthesis. The hospital mortality of 26% (11 patients) was high, due to the poor clinical condition of the patients. In a mean follow-up of 43.1 +/- 18,0 months, 20 patients could be restudied by clinical and echocardiographical investigation. Tricuspid insufficiency was found in all of the 9 patients who had been treated conservatively. Seven out of 11 patients operated showed no signs of TI, 3 had mild TI and 1 patient had severe TI. In the conservatively treated group, the preoperative mean pulmonary vascular resistance (PVR = 296 +/- 161 dynes x sex x cm-5), pulmonary artery pressure (PAP = 46.1 +/- 16.2 mmHg) and rise of right atrial V-wave (15.8 +/- 3.6 mmHg) were only slightly higher than n the operatively treated group (PVR - 274 +/- 146 dynes x sex x cm-5), PAP = 43.2 +/- 13.6 mmHg, V-wave = 18.5 +/- 6.4 mmHg) with no statistically significant difference. Preoperative hemodynamic findings in patients with and without TI a follow-up were also not significantly different. These results indicate that the recurrence of functional TI depends on the method of treatment, rather than preoperative increased PVR, PAP or V-wave rise.

Bioprosthesis↗
PubMed2004

O-ring attachments for transitional implant-retained overdentures.

The lack of proper stability and retention is frequently found in mandibular complete dentures. The stability and retention of existing complete dentures may be improved by using transitional implants (TIs) incorporating the O-ring retention system. This article describes the procedures used to convert an existing conventional complete denture to a TI-retained complete overdenture with O-ring.

Dental Abutments↗
PubMed2005

Fabrication and characteristics of bioactive sodium titanate/titania graded film on NiTi shape memory alloy.

A bioactive sodium titanate/titania graded film was formed in situ on NiTi shape memory alloy (SMA) by oxidizing in H(2)O(2) solution and subsequent NaOH treatment and characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The bioactivity of the film was investigated using a simulated body fluid (SBF) soaking test. A titania (TiO(2)) layer was first found on NiTi substrate after oxidized in H(2)O(2) solution, and then a porous sodium titanate (Na(2)TiO(3))/titania film with many Ti--OH groups and a trace of Ni(2)O(3) was formed by the reaction of partial TiO(2) phase with NaOH solution. After immersion in SBF for 12 h, apatite was observed to nucleate and grow on the film. With longer soaking time, more apatite appeared on its surface but our control experiments didn't reveal any apatite formation on the chemically polished NiTi SMA, which indicates the bioactivity of NiTi implants could be improved by the formation of the bioactive film. Moreover, XPS depth profiles of O, Ni, Ti, and Na show the bioactive film possesses a smooth graded interface structure to NiTi substrate, which is in favor of sufficient mechanical stability of apatite layer by subsequent deposition in SBF.

Biocompatible Materials↗
PubMed1994

The effect of interleukin-1 beta (IL-1 beta) on the regulation of IL-1 receptor type I messenger ribonucleic acid and protein levels in cultured human endometrial stromal and glandular cells.

Because we hypothesize that the interleukin-1 (IL-1) system may be important in the dialogue between mother and embryo during the implantation process, we have analyzed the effect of IL-1 beta, a secretory product of the human embryo and human endometrium, on the mRNA and protein levels of IL-1 receptor type I (IL-1R tI) in the human endometrium. For this purpose, endometrial epithelial cells (EEC) and stromal cells (ESC) were isolated and cultured with progesterone (3.18 micrograms/mL) and epidermal growth factor (20 ng/mL) for 8 days in the presence or absence of hrIL-1 beta (20 pg/mL). EEC from proliferative and secretory endometrium expressed high levels of IL-1R tI mRNA compared to ESC, and these levels were not modulated by IL-1 beta. However, prostaglandin E2 levels peaked on day 4 in EEC treated with progesterone, epidermal growth factor, and IL-1 beta (208.7 +/- 92 ng/10(7) cells), whereas no prostaglandin E2 was detectable in cells not treated with IL-1 beta, indicating that these cells responded to IL-1 beta. With regard to ESC from secretory endometrium, IL-1 beta increased its own receptor mRNA levels (4 +/- 0.5-fold increase) after 8 days in culture. However, when ESC were isolated from proliferative endometrium, an up-regulation of IL-1R tI (3.5 +/- 0.5-fold increase) was observed on days 6 and 8 of culture regardless of the presence or absence of IL-1 beta. Immunoreactive IL-1R tI was identified in cultured EEC and ESC, and patterns similar to those of mRNA were observed. The constitutive presence of IL-1R tI in EEC, which was not affected by IL-1 beta, and the up-regulation of IL-1R tI mRNA by its ligand IL-1 beta in ESC isolated during the luteal phase suggest a role for the IL-1 system in human implantation.

Endometrium↗
PubMed1997

Organic surface chemistry on titanium surfaces via thin film deposition.

In order to develop a synthetic strategy for the fine tuning of the interfacial properties of titanium-based implants and implant parts, a thin polymeric film was deposited from ethylene plasma on the surfaces of Ti foils. The intended aim was to further modify the adherent, delamination-resistant organic coating using the techniques of surface modification of polymers to direct interfacial interactions at the metal foil-biological phase interface. In particular, air-plasma treatment and Ce(IV)-induced hydroxyethylmethacrylate grafting, two typical reactions of biomedical polymers surface chemistry, were used to improve cell adhesion or to impart cell resistance to the plasma-coated Ti. Results indicate that a plasma-deposited thin polymeric film effectively can act as a viable substrate for further surface chemical modifications and allow the application of a huge background of surface-modification polymers to metallic devices.

Animals↗
PubMed2004

Design of new titanium alloys for orthopaedic applications.

Parallel to the biofunctionalisation of existing materials, innovation in biomaterials engineering has led to the specific design of titanium alloys for medical applications. Studies of the biological behaviour of metallic elements have shown that the composition and structure of the material should be carefully tailored to minimise adverse body reactions and to enhance implant longevity, respectively. Consequently, interest has focused on a new family of titanium alloys: Ti-6Mo-3Fe-5Ta, Ti-4Mo-2Fe-5Ta and Ti-6Mo-3Fe-5Zr-5Hf alloys. The non-toxicity of the specially designed titanium alloys compared with osteoblastic cells has been ascertained using MTT and RN tests. In addition, phase transformations upon thermal processing have been investigated, with comparison with a well-defined beta titanium alloy. Optimum thermal processing windows (above 550 degrees C) have been designed to generate a stable and nanostructured alpha phase from the isothermal omega phase that precipitates in a low temperature range (150-350 degrees C). The generation of such nanostructured microstructures should provide a promising opportunity to investigate tissue-biomaterial interactions at the scale of biomolecules such as proteins.

Alloys↗
PubMed2001

Discoloration of a titanium alloy removable partial denture: a clinical report.

With recent advances in dental technology, titanium is currently used for fabrication of crowns, fixed partial dentures, implant frameworks, and removable partial denture frameworks. The use of titanium-aluminum-vanadium (Ti-6Al-4V) alloy assumes that it imparts similar anti-corrosion characteristics to the commercially pure titanium. This clinical report describes a patient who experienced discoloration of a Ti-6Al-4V alloy removable partial denture.

Alloys↗
PubMed1995

Wear of the polyethylene acetabular cup. The effect of head material, head diameter, and cup thickness studied with a hip simulator.

Ultra-high molecular weight polyethylene acetabular cups backed by Ti-6Al-4V acetabular shells were articulated against Co-Cr-Mo alloy, ion-implanted Co-Cr-Mo alloy, and zirconia ceramic femoral heads in a hip joint simulator. Three tests of three million walking cycles each were run with five different head-cup combinations. The wear of the cups was measured gravimetrically at half a million cycle intervals. When the thickness of the cup was 10.9 mm, the mean wear rate was 0.14 mm/year against 28 mm dia. Co-Cr-Mo heads and 0.09 mm/year against ion-implanted 28 mm Co-Cr-Mo heads. When the thickness of the cup was 7.0 mm, the mean wear rate was 0.04 mm/year against 28 mm zirconia heads, but when the thickness was 10.9 mm, no wear occurred against 28 and 32 mm zirconia heads. The results indicate that a significant reduction in the wear of the polyethylene cup can be expected if zirconia is used as the head material, instead of Co-Cr-Mo alloy or ion-implanted Co-Cr-Mo alloy. The diameter of the zirconia head, 28 vs. 32 mm, seems unimportant, but a cup thickness much below 10 mm may be disadvantageous.

Acetabulum↗
PubMed1994

New surface-hardened, low-modulus, corrosion-resistant Ti-13Nb-13Zr alloy for total hip arthroplasty.

To optimize the performance of total hip replacement, scientists and clinicians are seeking new materials and noncemented, press-fit designs that can improve load transfer to the bone and reduce the incidence of loosening and thigh pain. Currently used Co-Cr-Mo alloy has a relatively high elastic modulus (E = 227 GPa), which limits its ability to transfer load to the surrounding bone in the proximal calcar region. Thus to improve load transfer, designs are considered with less cross-sectional area to increase flexibility, but at the expense of fit and fill, and thus stability of the implant within the bone. Should stem loosening occur, the stem stresses may exceed the relatively low fatigue strength of the Co-Cr-Mo alloy and lead to stem breakage. To improve these conditions, lower modulus Ti-6Al-4V alloy (E = 115 GPa) is being used. More recently, a new lower-modulus (E = 79 GPa) Ti-13Nb-13Zr alloy has been developed which does not contain any elemental constituents associated with adverse cell response (i.e., Co, Cr, Mo, Ni, Fe, Al, V), and which possesses comparable or superior strength and toughness to existing Ti-6Al-4V alloy. The carefully selected Nb and Zr constituents improve bone biocompatibility and corrosion resistance compared to that of currently used implant metals. Additionally, a unique diffusion hardening (DH) treatment can be conducted during the age-hardening process of this near-beta alloy to produce a hardened surface with abrasion resistance superior to that of Co-Cr-Mo alloy. This also provides an improvement in the micro-fretting tendencies that may occur within femoral head-neck taper regions and modular interfaces of other implant designs. The present study describes the metallurgy and mechanical properties of this unique low modulus Ti-13Nb-13Zr alloy, and the heat treatments used to obtain the high strength, corrosion resistance, and surface hardening that renders this biocompatible alloy well-suited for press fit hip replacement applications. Because of the relatively lower beta transus (735 degrees C), this alloy is also much easier to net shape forge into more complex stem designs.

Alloys↗
PubMed1989

[Study on biocompatibility of titanium alloys].

The biocompatibility of two different titanium alloys, Ti-6Al-4V ELI and Ti-5Al-2, 5Fe, and pure titanium were evaluated. The results were as follows: 1) Titanium alloys were implanted into the dorsal subcutaneous tissues of the Hartley guinea-pig for 12 weeks, immersed in calf serum or in Ringer's solution for 8 weeks. The surface changes of the titanium alloys were observed by SEM and the chemical composition was analyzed by XMA. No evident surface changes were found. 2) Three hundred mg, 200 mg and 100 mg of the powders of the tested materials were immersed in 2ml of Eagle's MEM, incubated for 1-7 days, 8-21 days and 22-70 days at 37 C degrees. The amount of metallic elements dissolved in the solutions was measured by ICP and AAS. The detected corrosion rates of V and Al contained in the solution, in which Ti-6Al-4V ELI 100 mg was immersed for 1-7 days, were 194.3 +/- 17.6 and 73.0 +/- 28, 1 pg/mg alloy/day, respectively. V was released more than Al. The amount of Ti was below the detectable limit. The solution Ti-5Al-2.5 Fe 100 mg immersed for 1-7 days contained 31.9 +/- 34.4 pg/mg alloy/day Fe and 25.7 +/- 6.3 pg/mg alloy/day Al. Only in the solution 300 mg immersed for 1-7 days was Ti detected at 1.4 pg/mg alloy/day. 3) By the bacterial mutation assay of Salmonella typhimurium TA 98, Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA, the solutions, in which the tested materials were immersed, were not found to be mutagenic. 4) By the UDS assay, the grain counts on autoradiography with the solutions, in which the tested materials were immersed, were not greater than the negative control. The results suggest an excellent corrosion resistance of the titanium alloys. Mutagenicity was negative by these mutation assays, indicating that the tested alloys and pure titanium are safe for humans and animals.

Animals↗
PubMed2003

Acid pretreatment of titanium implants.

The purpose of this study was to evaluate the effectiveness of several methods of cleaning titanium surfaces as pretreatment for surface modifications by analyzing the chemical interaction of three acids, such as Na(2)S(2)O(8),H(2)SO(4) and HCl, followed by rinsing with acetone or ultrapure water. Chemical evaluation, using X-ray photoelectron spectroscopy (XPS), and mechanical evaluation, using nanoindentation, were employed. XPS revealed that an untreated Ti surface consisted of carbon- and nitrogen-containing contaminant and titanium oxide layer on metallic titanium substrate. The method involving the combination of 10 N HCl and acetone was the most effective of all the methods investigated. Such a combination most effectively reduced values of contamination parameters C/Ti and N/Ti, as well as the intensity of the titanium oxide component in Ti 2p spectra. Chlorine was barely detected from the surface treated with HCl in any concentration. Sulfur from the residual S(2)O(8)(2-) or SO(4)(2-), however, was detected from the samples treated with either Na(2)S(2)O(8) or H(2)SO(4). The S/Ti values depended on concentration of the acidic solution. In addition, nanoindentation measurements revealed that Young's modulus of the surface treated with 0.1-10 N HCl was not significantly different from that of an untreated surface (p > 0.05). Consequently, the HCl/acetone treatment is proposed as an excellent decontamination method for the surface preparation process of Ti.

Acids↗
PubMed2004

Antibacterial titanium plate anodized by being discharged in NaCl solution exhibits cell compatibility.

Implant surfaces should be modified to achieve excellent cell compatibility as well as antibacterial activity. Our previous study demonstrated that titanium plates anodized by being discharged in NaCl (Ti-Cl) exhibited high antibacterial activity. Since Ti-Cl was prepared with a NaCl solution, we hypothesized that Ti-Cl would exhibit low toxicity toward cells. The aims of this study were to characterize the surface of Ti-Cl and investigate the cell compatibility (MC3T3-E1 and L929 cells) of Ti-Cl. The results demonstrated that, since the TiCl(3) formed on the Ti-Cl surface was hydrolyzed into HCl, HClO, and TiOH after immersion in pure distilled water, TiCl(3) contributed to the antibacterial activity of Ti-Cl. On the other hand, TiO formed on the Ti-Cl surface enhanced cell extension and cell growth through a larger adsorption of fibronectin compared with the pure titanium control. These findings suggest that antibacterial titanium is a promising material for use in dental implant systems.

3T3 Cells↗
PubMed1986

Alleviation of estrogen-induced hyperprolactinemia through intracerebral transplantation of hypothalamic tissue containing dopaminergic neurons.

Prolactin-secreting pituitary tumors can be induced in young rats through prolonged estrogen treatment. Recent evidence suggests that such tumors are associated with a degeneration of tuberoinfundibular dopaminergic (TI-DA) neurons, which normally inhibit prolactin secretion by the anterior pituitary's lactrophs. For this study, chronic hyperprolactinemia was induced in young, ovariectomized Fisher 344 rats through Silastic capsule implants of 17 beta-estradiol, placed subcutaneously for 1 month prior to removal. Rats with such estrogen-induced hyperprolactinemia then received transplants of neonatal arcuate-median eminence (ME) tissue (containing TI-DA neurons) or amygdala (control) tissue, placed either within the third ventricle or bilaterally within the hypothalamus. Blood samples were obtained 1 month after transplantation and prolactin concentrations measured by radioimmunoassay. Two of 4 animals receiving ventricularly-placed arcuate-ME transplants and 4 of 7 animals receiving bilateral arcuate-ME transplants showed substantial reductions in plasma prolactin levels compared to mean values in control animals. Follow-up catecholamine (CA) histochemistry indicated a bright fluorescence intensity in the median eminence of animals remaining hyperprolactinemic with ineffective transplants. Furthermore, in sharp contrast to the very low, nonpulsatile LH levels found during a second bleeding in recipients bearing ineffective transplants, recipients with effective arcuate-ME transplants had the high, pulsatile levels of LH characteristic of normal, ovariectomized rats. These data suggest that developing TI-DA neurons, within effective arcuate-ME transplants, became functional to reinstate or accentuate DA inhibition of prolactin secretion and, in so doing, indirectly normalized LH secretion as well.

Animals↗
PubMed1991

Ion implantation effects on friction and wear of joint prosthesis materials.

The literature contains many results from in vitro friction and wear tests for simulating the behaviour of human joint prostheses. However, they are difficult to correlate, even when they are not contradictory. In friction tests, several friction-mechanisms occur when the Ti-6AI-4V titanium alloy rubs against the UHMWPE polyethylene. Corrosion effects which increase wear happen when the 316L stainless steel is used in Ringer's solution. Ion implantation surface treatments have been performed on these three materials. When the operating conditions were optimized, an important reduction of wear and corrosion was observed. The property improvements are due to structural modifications in a thin layer of the materials.

Alloys↗
PubMed1977

New prospects for a prolonged functional life-span of artificial hip joints by using the material combination polyethylene/aluminium oxide ceramin/metal.

Investigations over the years have shown that the mirror-finished Al2O3 ceramic is a much more suitable frictional counterpart to ultrahigh molecular weight (UHMW) polyethylene than metal. Despite the extremely gread hardness difference between polyethylene and Al2O3 ceramic, a considerable lower wear rate is obtained for the polyethylene socked with this new low-friction material combination. The unexpectedly favorable tribological behavior of this ceramic material in contact with polyethylene may be attributed to the following factors: better values for corrosion resistance characteristics, wettability with liquids, surfact gloss, hardness, and scratch resistance of the ceramic material in comparison with those of the hitherto used metallic implant materials (AISI-316L steel or cast Co-Cr-Mo alloy). It appears that, by using this new combination of materials for the socket and the ball, it will be possible to prolong the service life of artificial hip joints considerably without having effecy any fundamental changes in the present design and implantation principle retaining the hitherto used anchorage shaft made of wrought Co-Ni-Cr-Mo-Ti alloy Protasul-10 of extremely high corrosion fatigue strength.

Alloys↗
PubMed2004

Mechanical and biological properties of hydroxyapatite reinforced with 40 vol. % titanium particles for use as hard tissue replacement.

Hydroxyapatite (HA)-based composite reinforced with 40 vol. % Ti particles was fabricated by the optimal technical condition of hot pressing technique. The mechanical and biological properties of the composite were studied by mechanical and in vivo methods. The experimental results show that HA and Ti phases are the predominant phases of the composite with partially decomposition of HA phase into alpha-Ca3(PO4)2 and Ca4O(PO4)2. Comparing with HA-20 vol. % Ti composite manufactured under the same conditions, HA-40 vol. % Ti composite with similar elastic modulus (79.3 GPa) and Vicker's hardness (2.94GPa) has a higher bending strength (92.1 MPa). Moreover, fracture toughness of HA-40 vol. % Ti composite with crack bridging as the chief toughening mechanisms can reach 2.692 MPa m(-1) , which can meet the basic toughness demand of the replaced hard tissues for heavy load-bearing applications. Work of fracture of HA-40 vol. % Ti composite is 91.2J m2, which is 22.9 times that of pure HA ceramic and even 2.4 times that of Al2O3 bioceramic. The results of in vivo studies show HA-40 vol. % Ti composite has excellent biocompatibility and could integrate with bone. In the early stage after the implantation of the samples, the osteointegration ability of the composite is better than that of pure titanium.

Animals↗