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PubMedDate not supplied

Effects of fluoride-modified titanium surfaces on osteoblast proliferation and gene expression.

PURPOSE: The objective of this study was to test the hypothesis that fluoride-modified titanium surfaces would enhance osteoblast differentiation. Osteoblast growth on a moderately rough etched fluoride-modified titanium surface (alteration in cellular differentiation) was compared to osteoblast growth on the same surface grit-blasted with titanium dioxide. The potential role of nanometer-level alterations on cell shape and subsequent differentiation was then compared. MATERIALS AND METHODS: Human embryonic palatal mesenchymal (HEPM) cultures were incubated on the respective surfaces for 1, 3, and 7 days, followed by analysis for cell proliferation, alkaline phosphatase (ALP) -specific activity, and mRNA steady-state expression for bone-related genes (ALP, type I collagen, osteocalcin, bone sialoprotein [BSP] II, Cbfa1, and osterix) by real-time polymerase chain reaction (PCR). RESULTS: The different surfaces did not alter the mRNA expression for ALP, type I collagen, osterix, osteocalcin, or BSP II. However, Cbfa1 expression on the fluoride-modified titanium surface was significantly higher (P < .001) at 1 week. The number of cells on this surface was 20% lower than the number of cells on the surface TiO2-blasted with 25-microm particles but not significantly different from the number of cells on the surface TiO2-blasted with 125-microm particles. Cells grown on all the titanium surfaces expressed similar levels of ALP activity. CONCLUSIONS: The results indicated that a fluoride-modified surface topography, in synergy with surface roughness, may have a greater influence on the level of expression of Cbfa1 (a key regulator for osteogenesis) than the unmodified titanium surfaces studied.

Acid Etching, Dental↗

PubMedDate not supplied

Osteoblast attachment on titanium disks after laser irradiation.

PURPOSE: Osteoblast attachment on titanium surfaces is necessary to achieve new bone formation and osseointegration. The purpose of this study was to examine osteoblast attachment on irradiated titanium disks. MATERIALS AND METHODS: Machined, hydroxyapatite (HA)-coated, sandblasted, and titanium plasma-sprayed (TPS) surfaces were irradiated with either a carbon dioxide (CO2) or an Er,Cr:YSGG laser. A control group of nonirradiated disks was also examined. Osteoblast cultures were cultivated on the titanium disks and examined with scanning electron microscopy. RESULTS: The findings demonstrated that osteoblasts could be grown on all of the surfaces. Pseudopodia and a spread of cells that demonstrated maturation were observed on the lased irradiated titanium disks. CONCLUSIONS: The data show that laser irradiation of titanium surfaces may promote osteoblast attachment and further bone formation.

Cell Adhesion↗

PubMed1989

[Characterization of surface films formed on titanium in electrolytic solutions].

In order to understand the interface-phenomena between titanium and biological tissue, the surface film formed on titanium in electrolytic solutions was examined using X-ray photoelectron spectroscopy (XPS). The composition of the surface film on titanium before immersion into solution is close to TiO2 and that of Ti-6 Al-4 V is a mixture of TiO2 and Al2O3. These surface films change to a complex phosphate of titanium and calcium containing hydroxyl radicals and hydrates when the specimens are immersed in an electrolytic solution. The compositions of the surface films of titanium and Ti-6 Al-4 V are almost the same except that the film on Ti-6 Al-4 V is thicker and contains more hydrates than that on titanium. Vanadium in Ti-6 Al-4 V, and sodium, chlorine, and sulfur in the solution are not responsible for the formation of the films.

Aluminum Oxide↗

PubMed1994

[The long-term fracture resistance of orthodontic nickel-titanium wires].

This study reports on the long-term fracture resistance of orthodontic nickel titanium wires, a material property that has not been investigated thoroughly, yet. A computer-controlled apparatus was designed to perform long-term bending tests. The investigated material comprised 9 nickel titanium wires (dimensions 0.016", round and 0.016" x 0.022", rectangular) as well as a stainless steel and a beta-titanium wire that were included as reference. Compared with the steel wire, the nickel titanium wires exhibited 2- to 5-fold higher yield forces in bending. At a specified deflection angle, the generated bending forces of the nickel titanium wires reached one half to one fourth of the values of steel. The fracture resistance under longterm loading was determined using the Wöhler-method. After 10(5) loadings, 0.016" nickel titanium wires were subject to break failure, if forces exceed values greater than 1.2 to 3.1 N. Steel and TMA wires could be loaded with forces of up to 4.4 and 3.7 N, respectively. The 0.016" x 0.022"-rectangular wires allowed forces of approximately twice this magnitude. Elastic fatigue of the superelastic specimens "Memorywire", "Rematitan Lite", and "Sentalloy medium" showed up as hardening of the wire by up to 70%. Material degradation lead to a severe deformation of the hysteresis loop and to plastic deformation. Work-hardened martensitic NiTi wires did not show these effects to this extent.

Dental Alloys↗

PubMed1993

Binding of murine osteoblastic cells to titanium disks and collagen I gels: implications for alternative interpretations of osseointegration.

Using 3H-thymidine-labeled MC3T3-El osteoblastic cells, the number of osteoblasts bound to titanium surfaces after various surface treatments and incubation periods was directly measured. MC3T3-El cell binding to titanium surfaces was saturable at a low level (approximately 10,000 cells/cm2). Although treatment of these surfaces with fibronectin, keratin sulfate, and the fibronectin-derived peptide GRGDS (glycine-arginine-glycine-glutamate-serine) increases cellular binding by 29% to 31%, the relative binding to titanium was 5 to 10 times lower than binding to collagen I gels. A collagen I matrix competed with the commercially pure titanium surfaces for cell binding from solution, suggesting that direct binding of osteoblasts to titanium surfaces present within an organic matrix may not be favored. The significance of immediate and direct bone cell attachment to titanium surfaces for osseointegration should be reevaluated.

3T3 Cells↗

PubMedDate not supplied

Surface characterization of radio-frequency glow discharged and autoclaved titanium surfaces.

To characterize titanium surfaces treated with radio-frequency glow discharge (RFGD) after media exposure, surface chemical analyses were performed using x-ray photoelectron spectroscopy. Auger electron spectroscopy, and Fourier transform infrared-reflection absorption spectroscopy (FTIR-RAS). The RFGD treatments resulted in a cleaner surface as compared to as-sputtered or as-autoclaved titanium specimens. The oxide thickness of RFGD-treated titanium specimens was not statistically different from the as-autoclaved and as-sputter cleaned titanium specimens. Exposure to a phosphate-buffered saline solution revealed a greater deposition of calcium and phosphorous on the RFGD-treated surfaces. Auger electron spectroscopy depth profiles showed that calcium and phosphorous ions diffused into the titanium oxide layer. The calcium and phosphorous deposits were identified as amorphous calcium phosphate compounds using FTIR-RAS. These results suggest that RFGD treatments of titanium enhance calcium and/or phosphate affinity because of an increase in elemental interactions at the surface, thereby resulting in the formation of amorphous calcium phosphate compounds.

Buffers↗

PubMed1996

The value of magnetic resonance imaging of the postoperative spine with titanium implants.

Magnetic resonance (MR) evaluation was performed on patients with titanium spine implants. The objective was to determine the value of conventional MR for evaluating the postoperative spine with titanium implants. The value of MR imaging for evaluation of the postoperative spine without metal implants is well known. The results of MR evaluation of the titanium instrumented spine have not been explored. Thirty patients with titanium spine implants underwent MR evaluation. Indications included pain, neurologic deficit, decompression evaluation, and infection. The titanium implants caused only local MR signal void and did not interfere with the imaging of the adjacent soft tissues. This provided significant information and helped determine whether further surgical intervention was required. There is significant value of MR evaluation of the post-operative spine without compromise from titanium implants.

Adolescent↗

PubMed1996

Effect of surface topography of titanium on surface chemistry and cellular response.

Surface topography plays a critical role in the interaction of dental implants with adjacent tissues. It has been hypothesized that an increase in surface roughness will result in an increase in calcium and phosphorus deposition after immersion in a simulated physiological solution and will increase protein production and calcium uptake by osteoblast-like cells. With the use of a profilometer, titanium samples ground with 600 grit silicon carbide paper were observed to have an average roughness (Ra) value of 0.28 +/- 0.03 micron, whereas titanium samples polished with 0.3 micron Al2O3 exhibited a Ra value of 0.11 +/- 0.01 micron. X-ray photoelectron spectroscopy analyses indicated the presence of calcium, phosphorus, sodium, and chlorine on both surface conditions after immersion in a protein-free physiologic solution. No significant difference in calcium and phosphorus concentrations were observed between the 600 grit or Al2O3 polished titanium samples after immersion in solution. The Ca/P ratio for both 600 grit and Al2O3 polished titanium was in the range of 0.8 to 1.1 after 12 days in solution. The percent protein retained by the rat bone marrow cell layer on both the Al2O3 polished and 600 grit titanium surfaces increased dramatically during the initial 3 days of the study. The 45Ca assays revealed no significant difference in cellular calcification on Al2O3 polished and 600 grit titanium surfaces. For both the Al2O3 polished and 600 grit surfaces, a sharp increase in 45Ca incorporation was observed after 9 days incubation.

Aluminum Oxide↗

PubMed1996

Surface reaction between titanium castings and investments.

The selection of investments suitable for titanium castings is critical because the surface-reacted layer greatly affects their mechanical properties. This study analyzed the interfacial zone of titanium castings obtained from various commercial investments and examined the relationship between the surface-reacted layer and the hardness. CP titanium disks (20 mm diameter, 1 mm thick, n = 5) were cast using eight commercial casting systems and investments for titanium casting: two alumina-based investments (T-invest, CD-titan investment), two spinel-based investments (Titanmold, Titavest MZ), three zirconia-based investments (Asahivest-D, Titaniumvest EX, Tycast investment TM), and a magnesia-based investment (Selevest CB). The Vickers hardness of cast disks in cross-section was tested at 50 microns intervals from the surface to 0.5 mm in depth. The cross-section was observed metallurgically, and an elemental mapping measurement of the reacted layer was conducted under the EPMA. The Vickers hardnesses at 50 microns from the surface of the specimens ranged 312 to 624 and were significantly different among the investments (p < 0.01). The thickness of the reacted layer, rich in O, Si, Al, Zr, Mg, and P, ranged from 10 to 60 microns. No correlation was seen between the thickness of reacted layer and the hardness (p > 0.05). However, the specimens cast with alumina-based and zirconia-based investments were harder than the spinel-based and magnesia-based investments at 500 microns. Although the free energies of metal oxide formation of alumina and zirconia were lower than titania, these data suggest that silica, alumina and zirconia were reduced by contact with molten titanium. Accordingly, silicon, aluminum and zirconium diffused to the interior of the titanium castings and changed their mechanical properties.

Aluminum Oxide↗

PubMed1997

Instrument deterioration with usage: nickel-titanium versus stainless steel.

Nickel-titanium instruments purportedly resist deformation and loss of sharpness better than do stainless steel instruments but may be more susceptible to breakage. The processes of wear and breakage of nickel-titanium and stainless steel instruments were examined. Sixty files of five types (12 each) and three manufacturers were used. All were used repeatedly in curved canals until failure or for a maximum of 22 minutes. Each instrument was examined with scanning electron microscopy both new (control) and at spaced intervals for evidence of wear and fatigue. All new instruments were of good quality. Stainless steel instrument tended to wear the most rapidly, and next were nickel-titanium rotary instruments; the most resistant to wear were nickel-titanium hand instruments. There were few instrument separations. In general, nickel-titanium (particularly hand) instruments resisted deterioration better than did stainless steel. Nickel-titanium rotary instruments (2 of 12) had the most breakage.

Dental Alloys↗

PubMedDate not supplied

Fatigue resistance of titanium-nickel alloy cast clasps.

In this study fatigue resistance of experimentally prepared titanium-nickel (50.8% nickel and 49.2% titanium) cast clasps was evaluated in a simulated clinical situation. The change in force required to remove the titanium-nickel clasps was recorded under a repeated placement-and-removal test on steel model abutment teeth. Commercially-pure titanium, cobalt-chromium alloy, and gold-silver-palladium-copper alloy clasps were also tested for comparison. The tips of the clasps were located in the 0.25- and 0.50-mm undercut areas of the abutments. No significant changes in the retentive force were found in titanium-nickel clasps in the 1,010 repeated cycles, whereas the other three types of clasp revealed a significant decrease in the force required for removal during the test procedures (repeated analysis of variance P < 0.001). The results suggest that the cast titanium-nickel clasp may be suitable in removable prosthodontic constructions because of its significantly less permanent deformation during service. This report also discusses clinical applicability and some current problems with this new application.

Analysis of Variance↗

PubMedDate not supplied

Effects of extracellular matrix constituents on the attachment of human oral epithelial cells at the titanium surface.

This in vitro study attempts to delineate the role of extracellular matrix (ECM) constituents at the epithelial tissue-implant interface. To know which ECM constituents have a beneficial influence on the behavior of epithelial cells, the attachment, proliferation, morphologic pattern, and differentiation or cytoskeletal organization of human oral epithelial cells on ECM-coated (type IV collagen, fibronectin, type I collagen, laminin, and vitronectin) and noncoated titanium surface have been evaluated and compared. In each experiment comparing commercially pure titanium and oxygen plasma-cleaned titanium, the same ECM constituents were used. In this study, type IV collagen could provide an excellent substratum for epithelial cell attachment on titanium surface, but vitronectin-coated titanium revealed lower effectiveness for attachment of epithelial cells than noncoated titanium. These results suggested that type IV collagen could be used as a means for obtaining good epithelial seal, whereas vitronectin could be used to restrain the attachment of epithelium to dental implants.

Adult↗

PubMed2000

Crystallization in low-energy deposition of titanium ions.

To investigate crystallization in the ion beam deposition process, titanium ions were deposited on silicon wafers at 105 and 55 eV. As titanium is an active metal, titanium compounds are formed by absorbing backfilled or residual gas. At energy levels of 105 or 55 eV, titanium crystallizes in a NaCl-type titanium compound with the backfilling of air. In all samples, (110)-oriented crystals grew with a rectangular lattice arrangement of titanium atoms. The open channel <110> of preferentially oriented crystal growth was parallel to the direction of incident ions normal to the substrate surface.

Journal Article↗

PubMed2000

Syntheses, characterizations, and single-crystal X-ray structures of soluble titanium alkoxide phosphonates.

Reactions of Ti(OiPr)4 with different phosphonic acids RPO3H2 (R = Ph, 4-CNPh, Me, tBu) in organic solvents have been investigated. In the presence of small amounts of water, the new molecular titanium oxide alkoxide phosphonates [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(RPO3)3].DMSO [R = Ph (1), Me (2), tBu (3), 4-CNPh (4)] were isolated. The single-crystal X-ray structure analyses of 1 and 2 revealed hexacoordinated titanium atoms and a connectivity of (111) for each phosphonate. Under rigorous exclusion of water, the reaction of Ti(OiPr)4 with tert-butylphosphonic acid in toluene gave the titanium phosphonate tetramer [Ti(OiPr)2(tBuPO3)]4 (5). A single-crystal X-ray structure analysis of 5 revealed a 5 + 1 coordination of the titanium atoms as a result of the (112) connectivity of each phosphonate; such a coordination mode has never been reported for a titanium phosphate, phosphonate, or phosphinate. Compounds 1-5 were characterized by FT-IR, 31P MAS NMR, and solution multinuclear NMR (1H, 13C(1H,) 31P(1H)) spectroscopies. 13C CP MAS NMR experiments were carried out on arylphosphonates 1 and 4. Solution NMR experiments were also used to investigate the exchange reaction between 1 and 2 and the conversion of 5 to [Ti4(mu 3-O)(OiPr)5(mu-OiPr)3(tBuPO3)3].iPrOH by partial hydrolysis in the presence of Ti(OiPr)4. The phosphonate clusters 1-5 are soluble in organic solvents and are likely intermediates in the sol-gel processing of inorganic-organic hybrids based on titanium oxide and phosphonate groups that we are currently developing.

Journal Article↗

PubMed1997

Titanium-Catalyzed Diastereoselective Epoxidations of Ene Diols and Allylic Alcohols with beta-Hydroperoxy Alcohols as Novel Oxygen Donors.

beta-Hydroperoxy alcohols 1-4 serve as effective tridentate oxygen donors for the highly diastereoselective, titanium-catalyzed epoxidation of ene diols 5a-e. Thus, in contrast to the bidentate tert-butyl hydroperoxide, the usual oxygen donor employed in Sharpless-type epoxidations and known to work poorly for polyhydroxy substrates, the tridentate beta-hydroperoxy alcohols efficiently replace the tridentate epoxy diol products 6a-e in the titanium template and thereby the catalytic cycle is sustained by replenishing with efficacy the loadedcomplex necessary for the oxygen transfer. Irrespective of the substitution pattern of the double bond or the configuration (erythro versus threo) of the diol functionalities in the ene diol substrate, high diastereoselectivities are observed for the epoxy diol products. The high stereochemical control is due to the rigid transition state for the oxygen transfer, which is imposed by the multiple titanium-oxygen bonding and coordination in the titanium template. The observed erythro selectivity for the ene diol derives from the additional bonding of its homoallylic hydroxy group to the titanium center, which fixes the substrate conformation in such a way that the oxygen atom to be transferred approaches from the side of the allylic oxygen functionality (cf. loaded complex A). This additional binding of the bidentate ene diol in the titanium template is also manifested in the enhanced reactivity of the ene diol versus the monodentate allylic alcohols. Nevertheless, the less reactive allylic alcohols also display a high erythro selectivity, provided these monodentate substrates possess 1,2-allylic strain. For the first time a direct, diastereoselective, and catalytic epoxidation of ene diols has been made available for synthetic applications, without recourse to protection group methodology.

Journal Article↗

PubMed2002

Processing and mechanical properties of autogenous titanium implant materials.

Pure titanium and some of its alloys are currently considered as the most attractive metallic materials for biomedical applications due to their excellent mechanical properties, corrosion resistance, and biocompatibility. It has been demonstrated that titanium and titanium alloys are well accepted by human tissues as compared to other metals such as SUS316L stainless steel and Co-Cr-Mo type alloy. In the present study, highly porous titanium foams with porosities <or=80% are produced by using a novel powder metallurgical process, which includes the adding of the selected spacers into the starting powders. The optimal process parameters are investigated. The porous titanium foams are characterized by using optical microscopy and scanning electron microscopy. The distribution of the pore size is measured by quantitative image analyses. The mechanical properties are investigated by compressive tests. This open-cellular titanium foams, with the pore size of 200-500 microm are expected to be a very promising biomaterial candidates for bone implants because its porous structure permits the ingrowths of new-bone tissues and the transport of body fluids.

Journal Article↗

PubMed2003

Titanium transport through the blood stream. An experimental study on rats.

Different metals are increasingly being used to manufacture implants, especially in the fields of dentistry and orthopedics. No metal or alloy is completely inert in vivo. The metal and the organic fluids interact releasing, for example, metallic products. Several hypotheses regarding the probable dissemination routes of titanium have been postulated, but its valence, the organic nature of its ligands and its potential toxicity have yet to be established. In a previous experimental study we demonstrated that i.p. injected titanium and zirconium oxides disseminate and deposit in organs such as liver and lung. The aim of this work was to study the eventual participation of blood cells in the transport mechanism of titanium employing the intraperitoneal injection of titanium oxide in rats as the experimental model. Twenty male Wistar rats, x: 100 g body weight, were intraperitoneally injected with 16x10(3) mg/kg b.w. of TiO(2) in saline solution. Blood samples were taken by heart puncture at 3 and 6 months; blood smears were performed and stained with safranin evidencing monocytes containing titanium particles. The results obtained in this study would indicate that one of the ways in which titanium is disseminated is through the blood stream, via blood cells.

Journal Article↗

PubMed2000

Titanium-niobium, a new finishing wire alloy.

The mechanical properties of the newly introduced titanium-niobium finishing wires were investigated. Both in bending and torsional loading mode, the stiffness, yield point, post-yield behavior, and springback of titanium-niobium wires were experimentally determined and compared to those of equally sized stainless steel wires. The experimentally obtained values were also validated with theoretical values from engineering formulas of cantilever deformations. The ratios for these parameters for the two materials proved to be different in bending and torsion. The stiffness of titanium-niobium in bending is roughly half of that of stainless steel, whereas in torsion it is roughly one-third. These characteristics enable the clinician to use titanium-niobium for creative bends without the excessive force levels of steel wires. The springback of titanium-niobium in bending is 14% lower than that of steel, whereas in torsion it is about the same or even slightly higher than that of steel, thus making it possible to utilize the wire for even major third-order corrections. Finally, the weldability of titanium-niobium wires was found to be good, so it is possible to weld wires of different dimensions together for the generation of differentiated force systems.

Journal Article↗