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At least 145 records · Page 8Linked to original sources
PubMed1997

Studies on dental high-speed cutting of commercial pure titanium (Ti) and free-machining titanium (DT-2F).

Some dental prostheses are formed by machining. The purpose of this study was to evaluate the dental high-speed cutting behaviour of free-machining titanium (Ti), the ease in cutting of which is metallurgically improved. Weight-load cutting tests were performed on commercial pure Ti and free-machining Ti, using a diamond point and a carbide burr. It became evident that the cutting effectiveness of two rotary cutting instruments on free-machining Ti was superior to that on commercial pure Ti due to the formation of accelerated cut debris. Cutting of free-machining Ti resulted in less damage of the carbide burr, compared with the cutting of commercial pure Ti. These results suggest that free-machining Ti is a suitable workpiece for dental Ti-based machined prostheses.

Carbon↗
PubMed1992

In-vivo comparisons of clot formation on titanium and hydroxyapatite-coated titanium.

We investigated in vivo clot formation on the surface of hydroxyapatite (HA)-coated titanium (Ti) implants and on non-coated Ti implants. Immediately after tooth extraction implant samples were inserted into the blood clot, in the same extraction site, for 1, 30, 60, or 120 seconds. Samples were processed for scanning electron microscopy (SEM). Qualitative observations of clotting topography were made by direct SEM viewing. Neither of the implant surfaces appeared to differ markedly in the degree of clotting during the 120 seconds of implantation; they revealed very early clot formation and limited clot attachment. These results were compared to the findings obtained in a previous study using identical methods with an intact periodontal ligament (PDL), root planed roots, and roots planed and treated with pH 1 citric acid. The PDL surface had the most rapid clot formation at all time periods. By 120 seconds, all root surfaces had completed clot formation.

Alloys↗
PubMed2001

Corrosion behavior of pure titanium and titanium alloys in fluoride-containing solutions.

The effects of fluoride concentrations and pH on the corrosion behavior of pure titanium, Ti-6Al-4V, Ti-6Al-7Nb alloys and a new Ti alloy adding palladium, which is expected to promote a repassivation of Ti were examined by anodic polarization and corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. The surface of the specimen was analyzed by X-ray photoelectron spectroscopy before and after the measurement. Pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys were easily corroded even in a low fluoride concentration in an acidic environment. The corrosion resistance of Ti-0.2Pd alloy was greater than those of pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys in the wide range of pH and fluoride concentrations. The high corrosion resistance of Ti-0.2Pd alloy was caused by the surface enrichment of Pd promoting a repassivation of Ti. The Ti-0.2Pd alloy is expected to be useful as a new Ti alloy with high corrosion resistance in dental use.

Acids↗
PubMed2002

Effects of fluoride and dissolved oxygen concentrations on the corrosion behavior of pure titanium and titanium alloys.

The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium, Ti-6Al-4V and Ti-6Al-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined using the corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. A decrease in the dissolved-oxygen concentration tended to reduce the corrosion resistance of Ti and Ti alloys. If there was no fluoride, however, corrosion did not occur. Under low dissolved-oxygen conditions, the corrosion of pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys might easily take place in the presence of small amounts of fluoride. They were corroded by half or less of the fluoride concentrations in commercial dentifrices. The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode more, even under the low dissolved-oxygen conditions and a fluoride-containing environment, than pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use.

Alloys↗
PubMed1991

Comparison of the early healing course of porous titanium with hydroxyapatite-coated porous titanium hip implants: clinical considerations for the use of hydroxyapatite coating in total hip replacement.

The role of hydroxyapatite (HA) coating in the fixation of human total joint prostheses remains to be established. Results of animal studies have been favorable, showing very rapid bone formation with a corresponding increase in bone-implant bond strength. In addition, the quantity of bone may be increased. This study compared identical porous titanium primary total hip implants with and without HA in similar patient populations. All of these patients were healthy and reliable, and had optimal bone geometry and bone quality for cementless fixation. The purpose of the study was to contrast the sequence of events, in the first year after surgery, between the two implant groups to identify the contribution of HA to early patient function and early radiographic appearance of the prosthesis. No significant clinical difference could be demonstrated between the two groups at 1 year from surgery. However, the HA group progressed more rapidly when comparing clinical scores at 6 months (P = .0058), and appeared to demonstrate more rapid bone remodeling at 6 months on the femoral side, although this observation did not quite make statistical significance (P = .0618). There was no difference between the acetabular components during the course of this study.

Female↗
PubMed1989

Comparison of titanium-tantalum and titanium-niobium alloys for application as dental implants.

For the diffusion bonding of Ti alloys to alumina, materials with a similar thermal expansion coefficient to alumina are required. Such materials were developed by alloying the biocompatible elements Ta and Nb to titanium (Ti-Ta30 and Ti-Ta40, Ti-Nb40 and Ti-Nb50). While measuring the corrosion behavior of these alloys in 0.9% saline solution, no difference could be observed. The Ti-Ta alloys are superior in their mechanical properties to Ti-Nb alloys.

Biocompatible Materials↗
PubMed1976

[Tissue reaction to an implant of a titanium hollow cylinder with a titanium surface spray layer].

A new implant consisting of a hollow cylinder of titanium is described. It is well suited to investigate the tissue reaction to several surface textures in the animal experiment (Macaca speciosa). From a test series, for which the implants were surfaced with powdered titan (titan plasma), one was selected which had been worn for 7 months as a partial support. The solid incorporation observed radiologically presents itself, light microscopically, as an immediate growing in of the bone into the rough implant surface. There is no evidence of the formation of a soft tissue bed. Electron microscope pictures reveal that the bone closely anchored to the titan plasma surface.

Animals↗
PubMed2001

Complete defluorination of 1,2,3,4-tetramethyl-5-(trifluoromethyl)cyclopentadiene by titanium tetrakis(dimethylamide)--selective formation of a cyclic hexanuclear titanium fluoroamide and 6,6-dimethylaminotetramethylfulvene.

1,2,3,4-Tetramethyl-5-(trifluoromethyl)cyclopentadiene (Cp*CF3-H, 1) reacts with [Ti(NMe2)4] (2) under mild conditions to give [Ti(mu-NMe2)(NMe2)(mu-F)(F)]6 (3) in nearly quantitative yield. The molecular structure of 3 consists of a ring of six [TiF2(NMe2)2] edge-bridged octahedra. Titanium complexes containing the Cp*CF3 ligand, which was the primary intention of these investigations, were not observed. C5Me4=C(NMe2)2 (4) was isolated as a by-product. The complete defluorination of an aliphatic CF3 group occurs during the reaction. The reaction mechanism involves the primary formation of a difluorofulvene intermediate C5Me4=CF2 (5), which was monitored by NMR studies. Density functional theory calculations predict a highly charged C6 atom (+0.87) in 5, which is discussed as the driving force of the reaction.

Journal Article↗
PubMed2005

Synthesis of titanium(IV) guanidinate complexes and the formation of titanium carbonitride via low-pressure chemical vapor deposition.

The mono(guanidinato) complex [Ti(NMe2)2Cl{i-PrNC[N(SiMe3)2]N-i-Pr}] (1) was prepared by reaction of [Ti(NMe2)2Cl2] with 1 or 2 equiv of the lithium guanidinate salt [Li{i-PrNC[N(SiMe3)2]N-i-Pr}]. Compound 1 has been characterized by X-ray crystallography. Treatment of TiCl4 with 2 equiv of [Li{i-PrNC[N(SiMe3)2]N-i-Pr}] resulted in the formation of dark red crystals. X-ray crystallography showed that these crystals consist of a 70:30 mixture of two bis(guanidinato) complexes, namely, [TiCl2{i-PrNC[N(SiMe3)2]N-i-Pr}{i-PrNC(N=CMe2)N-i-Pr}] (2) and [TiCl2{i-PrNC[N(SiMe3)2]N-i-Pr}{i-PrNC[N(H)-i-Pr]N-i-Pr}] (3). Both compounds 2 and 3 possess a transformed guanidinate ligand. Low-pressure chemical vapor deposition of either compound 1 or [TiCl2{i-PrNC(NMe2)N-i-Pr}] (4) at 600 degrees C results in thin films of titanium carbonitride.

Journal Article↗
PubMed1997

Monomeric Titanium(IV) Azides as a New Route to Titanium Nitride.

The reaction of Ti(NMe(2))(4) with 2 equiv of Me(3)SiN(3) in toluene solution affords a dark red polymeric material of composition [Ti(NMe(2))(2)(N(3))(2)](n) (1). If the reaction is carried out in pyridine (py) solution, dark red, crystalline [Ti(NMe(2))(2)(N(3))(2)(py)(2)] (2) is formed. Analogous reactions of Ti(NMe(2))(4) with 2 or 1 equiv of Me(3)SiN(3) in the presence of 1 equiv of bipyridyl (bipy) in toluene solution afford brown crystals of [Ti(NMe(2))(2)(N(3))(2)(bipy)] (3) and dark red crystals of [Ti(NMe(2))(3)(N(3))(bipy)] (4), respectively. Crystallographic data for 2: orthorhombic, C222(1), a = 7.120(1) Å, b = 15.899(3) Å, c = 16.946(4) Å, V = 1918.3(6) Å(3), rho = 1.310 g/cm(3), Z = 4. Crystallographic data for 3: monoclinic, I2/a, a = 7.358(2) Å, b = 16.808(4) Å, c = 14.837(6) Å, beta = 95.40(2) degrees, V = 1826.8(1) Å(3), rho = 1.368 g/cm(3), Z = 4. Crystallographic data for 4: monoclinic, P2(1)/c, a = 15.682(2) Å, b = 8.814(1) Å, c = 15.128(1) Å, beta = 108.39(1) degrees, V = 1984.2(4) Å(3), rho = 1.267 g/cm(3), Z = 4. Compounds 1 and 2 deposit thin films of titanium nitride (TiN) on silica and/or nickel substrates in the temperature range 300-400 degrees C. The TiN films deposited from precursor 2 are superior to those deposited from 1.

Journal Article↗
PubMed1992

["Erlangen Model" titanium socket. Study of the biomechanics of the "Erlangen Mode" titanium socket with and without supporting ring].

A multitude of prostheses are available for the reconstruction of severely arthrotic hip joints--especially for revising total arthroplasty. In order to find out more about the biomechanical efficiency of these special implants, we carried out computerized analyses on how the distribution of stress within the pelvis changes when employing the titanium socket component "Erlanger Modell" [TiAl 5 Fe 2.5], which can be used with a supporting ring in order to transfer the stress on the hip joint to the iliac bone and to the pubic bone in case the acetabulum should not be able to provide the stability needed by the socket. In a procedure described by Herzog, strain gauges are attached to the pelvis of freshly slaughtered cattle at the following sites, transmitting the relative bone expansion and torsion to a multipoint measuring instrument (Linseis L2100) and on-line to a computer: (1) superior ramus of the pubic bone; (2) front edge of the socket at the iliopubic eminence; (3) iliac bone on the outside of the pelvis; (4) socket roof, pars ossis ilei in the small pelvis; (5) socket roof, pars ossis ischii in the small pelvis. The quality of the implantation was monitored by the non-delayed force transmission from the femur through the hip arthroplasty onto the pelvis. With stress varying from 0 to 500 N in steps of 125 N we carried out four complete readings in order to ensure the reproducibility of the measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetabulum↗
PubMed2006

Photogeneration of titanium(III) from titanium(IV) citrate in aqueous solution.

Current interest in the biochemistry of Ti(IV) arises from its widespread use in white pigments and its potential in therapeutic agents. Citrate is known to form strong complexes with Ti(IV). We show here that Ti(III) citrate is generated in a facile manner and in good yield by the action of UV radiation on Ti(IV) citrate in aqueous solution. The Ti(III)-citrate species formed was isolated and characterised by UV-Visible spectroscopy, showing an absorption at 547 nm (epsilon=100 M(-1)cm(-1)), and by electron paramagnetic resonance (EPR) spectroscopy giving a resonance at g=1.949 (linewidth=60G) . An X-ray structure of the parent Ti(IV) complex in the form [TiNa(3)(C(6)H(6)O(7))(2)(C(6)H(5)O(7))(H(2)O)(6.8)].2H(2)O is reported along with a study of the reaction of Ti(IV)-citrate with N,N-ethylenebis(o-hydroxytoluene)glycine (EHTG), which was more rapid than those of other related Ti(IV) complexes.

Citric Acid↗
PubMed2003

Titanium(IV) tungstosilicate and titanium(IV) tungstophosphate: two new inorganic ion exchangers.

Crystalline phases of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been synthesised. The ion-exchange capacities of Ti(IV) tungstosilicate and Ti(IV) tungstophosphate have been reported as 0.44 and 0.80 mequiv./g, respectively. Both materials show monofunctional ion-exchange characteristic and are stable in 0.1 M solutions of HNO3, HCl, H2SO4 and acetone and benzene. Ti(IV) tungstosilicate is found to be more stable thermally than Ti(IV) tungstophosphate (loss in ion-exchange capacity was found as 58 and 80%, respectively for samples heated at 200 degrees C). The Kd values for heavy metals such as Pb, Hg, Cd, Sb, Co, Zn, Ni, Fe, Cr etc. have been reported in demineralised water and two surfactant media by batch processes. Cr3+, Fe3+ and Sn4+ are totally adsorbed on both the materials in demineralised water while a decrease in Kd value with increase in concentration of two surfactants is reported. On the basis of Kd values for metal ions, thirteen binary separations and five ternary separations on Ti(IV) tungstosilicate and thirteen different binary separations and four different ternary separations on Ti(IV) tungstophosphate have been achieved. Separation of methylamine from ethylamine has been done by GC on a column packed with Ti(IV) tungstophosphate.

Ion Exchange Resins↗
PubMed2005

Reductions by titanium(II) as catalyzed by titanium(IV).

The cobalt(III) complexes, [(NH3)5CoBr]2+ and [(NH3)5CoI]2+ are reduced by Ti(II) solutions containing Ti(IV), generating nearly linear (zero-order) profiles that become curved only during the last few percent of reaction. Other Co(III)-Ti(II) systems exhibit the usual exponential traces with rates proportional to [Co(III)]. Observed kinetics of the biphasic catalyzed Ti(II)-Co(III)Br and Ti(II)-Co(III)I reactions support the reaction sequence: [Ti(II)(H20)n]2+ + [Ti(IV)F5]- (k1)<==>(k -1) [Ti(II)(H2O)(n-1)]2+ + [(H2O)Ti(IV)F5]-, [Ti(II)(H2O)(n-1)]2+ + Co(III) (k2)--> Ti(III) + Co(II) with rates determined mainly by the slow Ti(IV)-Ti(II) ligand exchange (k1 = 9 x 10(-3) M(-1) s(-1) at 22 degrees C). Computer simulations of the catalyzed Ti(II)-Co(III) reaction in perchlorate-triflate media yield relative rates for reduction by the proposed active [Ti(II)(H2O)(n-1)]2+ intermediate; k(Br)/k(I) = 8.

Bromine↗
PubMed1979

Titanium and fluoride concentrations in titanium tetrafluoride and APF treated enamel.

Greater fluoride concentrations were obtained in enamel treated with phosphate/fluoride solutions than in that treated with TiF4 at similar pH's (1.0) and F concentrations (0.6M F and 1.6M F). However, fluoride solution without added phosphate at pH 1.0 and 1.6M F concentration produced lower fluoride concentrations in enamel than in TiF4 treated enamel. It is proposed that in TiF4 treated enamal the fluoride uptake may be dependent upon the amount of Ti introduced into the enamel.

Acidulated Phosphate Fluoride↗