Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Titanium”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2005

[The preparation of the multilevel holes and analysis of the pure titanium surface].

PURPOSE: Using sandblast, double acid-etching and H(2)O(2)/HCl solution treatment to establish a new implant surface, and to analyze the surface's morphology. METHODS: After being polished, sandblasted, cleaned, the titanium specimens were divided into six groups, i.e.A to F group. The specimens of group A were treated with low concentration of HF/HNO(3) solution, Group B was treated with low concentration of HF/HNO(3) solution and then H(2)SO(4)/HCl solution, Group C was treated after Group B and further with H(2)O(2)/HCl solution at 80degrees centigrade for 30 minutes, and subsequently heated at 400degrees centigrade for 1 hour. Group D was treated with high concentration of HF/HNO(3) solution, Group E was treated after Group D and then H(2)SO(4)/HCl solution, Group F was treated after E group and further with H(2)O(2)/HCl solution at 80degrees centigrade for 30 minutes, and subsequenty heated at 400degrees centigrade for 1 hour. RESULTS: The titanium surface sandblasted and ultrasonically cleaned exhibited a great deal of particles. The titanium plates treated with low concentration of HF/HNO(3) solution still had some particles, but there were much nano-holes on the titanium surface. The titanium plates treated with high concentration of HF/HNO(3) solution had no particles on the surface, but showed much micron-holes on the titanium surface. The titanium plates treated with H(2)SO(4)/HCl solution after HF/HNO(3) solution etching had all particles removed and got multilevel holes on the surface.The last H(2)O(2)/HCl method produced an anatase titania gel layer on the specimen surface. CONCLUSION: By altering the concentration of HF/HNO(3) solution, we could make different sizes of apertures on the titanium surface. Double acid-etching can remove all sandblasting particles embedded in titanium surfaces and form multilevel holes. The H(2)O(2)/HCl method can turn the rough non- crystallographic TiO(2) layer into the anatase titania gel layer.

Acid Etching, Dental↗
PubMed2006

[Effects of laser welding on bond of porcelain fused cast pure titanium].

OBJECTIVE: To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. METHODS: Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. RESULTS: No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. CONCLUSIONS: Laser welding does not affect low-fusing porcelain fused to pure titanium.

Dental Casting Technique↗
PubMed1989

[Properties of titanium dioxide-polymer composite with titanate coupling agents].

Titanium dioxide-polymethacrylate composites were prepared with triethyleneglycol dimethacrylate (TEGDMA), 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimeth ylexane (UDMA) and rutile structure titanium dioxide. The coupling agents used were isopropyldimethacrylisostearoyl titanate (KR7), isopropyltri (dioctylphosphate) titanate (KR12) and 4-methacryloxyethyl trimellitate anhydride (4-META). Compressive and transverse strengths of composites were determined under various experimental conditions. Compressive strength of composite with KR 7-treated titanium dioxide was higher than that with untreated titanium dioxide. Transverse strength of the composite with 4-META-treated titanium dioxide was higher than that with untreated titanium dioxide. Both compressive and transverse strengths increased when the titanium dioxide was treated with the mixture of KR7 and 4-META. Scanning electron microscopic observations of fractured composite surfaces showed titanium dioxide polymer interface failure with untreated specimens and polymer cohesive fracture with KR7 + 4-META-treated specimens. The results suggest that titanium dioxide treated with both KR7 and 4-META is useful as a pigment of the opaque material of fixed prosthodontic composite.

Composite Resins↗
PubMedDate not supplied

Interfacial reactions of cast titanium with mold materials.

PURPOSE: Dental casting requires replication of complex shapes with high fidelity. To achieve this objective, the problem of scale formation on titanium dental castings must be overcome. Scaling occurs readily at high temperatures because of the high reactivity of molten titanium with investment materials. The purpose of this study was to examine the effectiveness of using stable oxide coatings on the mold surface to reduce the interfacial reactions. MATERIALS AND METHODS: A traditional phosphate-bonded dental investment, a commercial titanium investment, and an experimental oxide coating were used for the molds. Pure titanium samples were cast, divested, and prepared for scanning electron microscopic and energy dispersive x-ray spectroscopic analyses. RESULTS: Layers of 7- to 10-micron-thick scale were formed on titanium castings during reaction with traditional mold materials. Interface reaction was reduced between the molten titanium and the investment material when yttrium oxide or zirconium oxide coatings were applied to the mold before casting. CONCLUSION: Less titanium-mold interfacial reactions occurred when protective coatings were used as diffusion barriers for titanium casting. Y2O3-coating oxide particles applied without binder were entrapped in the cast titanium surface layer. Further study of a binder system for Y2O3 coating is needed.

Dental Casting Investment↗
PubMed2001

Achiral tetrahydrosalen ligands for the synthesis of C(2)-symmetric titanium complexes: a structure and diastereoselectivity study.

Achiral tetrahydrosalen ligands have been employed in the synthesis of chiral C(2)-symmetric titanium complexes. When combined with tetrahydrosalen ligands 2a and 2b, titanium tetraisopropoxide liberated 2 equiv of isopropyl alcohol and generated the (tetrahydrosalen)Ti(O-i-Pr)(2) complexes 3a and 3b. These complexes were shown to be C(2)-symmetric by (1)H and (13)C[(1)H] NMR spectrometry and X-ray crystallography. X-ray structures of 3a and 3b indicate that the bonding of the tetrahydrosalen ligand to titanium is different than the bonding of salen ligands to titanium. Whereas salen ligands usually bind to titanium in a planar arrangement, the tetrahydrosalen is bonded with the phenoxide oxygens mutually trans. When bound in this fashion, the nitrogens of the tetrahydrosalen ligand and the titanium become stereogenic centers. The use of titanium complexes of high enantiopurity in the generation of tetrahydrosalen titanium adducts resulted in a maximum diastereoselectivity of 2:1. The diastereoselectivity obtained using chiral titanium alkoxide complexes was greater than the diastereoselectivity observed when a tetrahydrosalen ligand derived from (S,S)-trans-diaminocyclohexane was employed.

Journal Article↗
PubMed2005

FTIR spectroscopic study of titanium-containing mesoporous silicate materials.

The surface acidity of different mesoporous titanium-silicates, such as well-organized hexagonally packed Ti-MMM, Ti-MMM-2, Ti-SBA-15, and amorphous TiO(2)-SiO(2) mixed oxides (aerogels and xerogels), was studied by means of FTIR spectroscopy of CO adsorbed at 80 K and CD(3)CN adsorbed at 293 K. The surface hydroxyl groups of mesoporous titanium-silicates with 2-7 wt % Ti revealed a Brönsted acidity slightly higher to that of pure silicate. TiO(2)-SiO(2) xerogels revealed the highest Brönsted acidity among the titanium-silicates studied. CO adsorption revealed two additional sites on the surface in comparison to pure silicate, characterized by nu(CO) from 2185 (high pressure) to 2178 (low pressure) cm(-1) and from 2174 (high pressure) to 2170 (low pressure) cm(-1). These bands are due to CO adsorbed on isolated titanium cations in the silica surrounding or having one Ti(4+) cation in their second coordination sphere and due to CO interactions with Ti-OH groups, respectively. CD(3)CN adsorption similarly revealed the existence of two additional sites, which were not detected for pure silicate: at 2289 cm(-1) due to CD(3)CN interaction with titanol groups and from 2306 (low pressure) to 2300 (high pressure) cm(-1) due to acetonitrile interaction with isolated framework titanium cations with probably one Ti(4+) cation in their second coordination shell. The spectroscopic results are compared with computational data obtained on cluster models of titanium-silicate with different titanium content. According to the IR data, the Ti accessibility on the surfaces for mesoporous titanium-silicates with similar Ti loading (2 wt %) was found to fall in the order TiO(2)-SiO(2) aerogel approximately TiO(2)-SiO(2) xerogel > Ti-MMM approximately Ti-MMM-2 > Ti-SBA-15. This order (except TiO(2)-SiO(2) xerogel) correlates with the catalytic activity found previously for titanium-silicates in 2,3,6-trimethylphenol oxidation with H(2)O(2).

Journal Article↗
PubMed1996

Light and electron microscopic studies of bone-titanium interface in the tibiae of young and mature rats.

Bone-titanium contact was examined in young and mature rats on various days after insertion of pure titanium into the tibia. Under light microscopy, on the 14th day, lamellar mature bone was initially formed, and was seen to make direct contact with the titanium in both groups. In young rats on the 28th day, bone-titanium contact was greater than that in mature animals. On 1-micron sections, an amorphous zone 0.5-1.0 micron thick was found around the titanium, and a slender cell layer lay parallel to the implant, forming the superficial layer of the amorphous zone. Ultrastructurally, these slender cells were identified as osteoblastlike cells and made direct contact with the implant via a 20-50-nm thin amorphous zone. Below this cell layer, a collagen-containing, poorly mineralized zone was present and bordered by lamellar bone with a lamina limitans-like structure. However, this cell layer was absent in places, and therefore the thick amorphous zone without slender cell layer consisted ultrastructurally of a 20-50-nm thin amorphous zone and a poorly mineralized zone bordered by the lamellar bone. Sometimes this poorly mineralized zone was absent, and in such cases, the lamellar bone contacted the titanium by the thin amorphous zone formed on the lamina limitans-like structure. Thus, although bone was seen to make contact with the titanium implant, ultrastructurally a 20-50-nm thin amorphous zone, a slender cell layer, and/or a poorly mineralized zone were interposed between the bone and titanium.

Animals↗
PubMed1997

Surface modifications of titanium in calcium-ion-containing solutions.

The surface of titanium was modified in calcium-ion-containing solutions to improve bone conductivity. Three kinds of aqueous solutions for the modification were prepared using calcium nitrate, calcium chloride, and calcium oxide. The pH values of the solutions were 3.9, 7.4, and 12.6, respectively. At first, anatase powder was immersed in the solutions of 7 days to confirm the effect of the solutions on the modification. As a result, calcium titanate was formed on the anatase powder, indicating that the titanium surface was possibly modified by the solutions. Titanium plates were then immersed in the solutions at ambient temperature for 7 days, washed by deionized water, and dried. X-ray photo-electron spectroscopy of surface-modified titanium revealed that the surface-modified layer contained calcium hydroxide and/or calcium titanate. The surface-modified layer in which titanium was modified was thickest in this order: calcium oxide, calcium chloride, and calcium nitrate solutions. Apatite was formed on the surface-modified titanium in Hanks' solution while apatite was undetected on unmodified titanium. Therefore, the surface modification of titanium may improve bone conductivity. The amount of apatite corresponded to the thickness of the surface-modified layer and the amount of calcium in the layer.

Apatites↗
PubMed1998

Repassivation of titanium and surface oxide film regenerated in simulated bioliquid.

The change in potential during repassivation of titanium in artificial bioliquids was examined, and the regenerated surface oxide film on titanium was characterized using X-ray photoelectron spectroscopy and Auger electron spectroscopy to elucidate the repassivation reaction of titanium in a biological system. The repassivation rate in Hanks' solution was slower than that in saline and was not influenced by the pH of the solution. This indicates that more titanium ions dissolve in a biological system than hitherto was predicted when the surface film is destroyed. Phosphate ions are taken up preferentially in the surface film during regeneration, and the film consists of titanium oxide and titanium oxyhydroxide containing titanium phosphate. Calcium ions and phosphate ions are adsorbed by the film after regeneration, and calcium phosphate or calcium titanium phosphate is formed at the outermost surface. Ions constituting Hanks' solution other than calcium and phosphate were absent from the surface oxide.

Biocompatible Materials↗
PubMed1998

An immunoelectron microscopic localization of noncollagenous bone proteins (osteocalcin and osteopontin) at the bone-titanium interface of rat tibiae.

This study was designed to investigate by postembedding immunogold method the localization and distribution of osteocalcin (Ocl) and osteopontin (Opn) at the bone-titanium interface in rat tibiae 14 and 28 days postimplantation to determine which bone proteins are present at this interface. Both proteins were widely distributed on the newly formed bone and accumulated predominantly in the region of bone close to the titanium, in electron-dense patches in the bone, and at the osteocytic lacunae. Collagenous osteoid showed little or no labeling for either Ocl or Opn. An amorphous zone (20-50 nm) was interposed between the titanium and interfacial slender cells, osteoid, or bone, and was labeled strongly for Ocl but only weakly for Opn. Furthermore, a second electron-dense layer, the lamina limitans, which faces the titanium, was labeled strongly for Opn but weakly for Ocl. Ocl as a marker protein of osteoblasts was sometimes found in the granules and vesicles of the interfacial cells and extracellularly in their intercellular spaces, close to the titanium. However, Opn was not detected in any granules. This is the first report to show that the amorphous zone contains large amounts of Ocl and small amounts of Opn, and that bone contacts titanium through this Ocl-rich amorphous zone. Furthermore, it is suggested that the interfacial cells seem to be osteoblasts, and that Ocl in the amorphous zone is produced and secreted by these cells and functions with Opn as a regulator of the mineralization front close to the titanium, and as a mediator of cell-matrix and matrix-matrix/mineral adhesion along the titanium.

Animals↗
PubMed1998

Effects of titanium-dental restorative alloy galvanic couples on cultured cells.

The potential exists for titanium and amalgams to become galvanically coupled in the oral cavity. While low galvanic corrosion rates have been measured in vivo for titanium-amalgam or mercury-free alloy couples, concerns exist over released corrosion products and adverse tissue responses. It was hypothesized in this study that coupling titanium to amalgams or gallium alloys increased the release of metallic corrosion products and decreased cellular activity and function. The effects of titanium coupled and uncoupled to a conventional amalgam, palladium-enriched spherical high copper amalgam, a dispersed type high copper amalgam, and a mercury-free gallium alloy were evaluated in 24-h cell culture tests. Viability, proliferation, and collagen synthesis were evaluated by the uptake of neutral red, 3H-thymidine, and immunoassay of procollagen, respectively, and compared to cells not exposed to any test material. The gallium alloy-titanium couple resulted in significant decreases in cellular viability, proliferation, and collagen synthesis as compared to the other coupled and uncoupled samples. Few differences in the cellular responses of the other coupled and uncoupled samples were observed. Atomic absorption analyses indicated increased release of metal ions from the amalgam and gallium alloy samples coupled to titanium as compared to their uncoupled condition, although the differences were not always significant. Galvanic corrosion of amalgam-titanium couples in the long term may become significant, and further research is needed. Coupling the gallium alloy to titanium may result in increased galvanic corrosion and cytotoxic responses.

Cells, Cultured↗
PubMed2002

Initial interaction of U2OS cells with noncoated and calcium phosphate coated titanium substrates.

From previous studies, we know that calcium phosphate (CaP) coated implants stimulate bone formation compared to uncoated implants. Nevertheless, the mechanism by which substrate surface characteristics affect cell function is unclear. In this study, we examined the initial interaction (30 min to 24 h) of U2OS cells with titanium substrates with or without a CaP coating. The effect of substrate roughness was also studied. When cell attachment was studied, we found that cells attached more readily to rough than to smooth surfaces. Also, more cells attached to the uncoated than to the CaP coated surface. After 24 h, cell numbers were similar for all substrate surfaces. Further, cells spread to a larger area on noncoated titanium than on the CaP coated substrates. At 24 h, the sequence of cell size was smooth titanium > rough titanium > CaP coated titanium. Shape measurements showed differences in cell shape between the cells on the different materials only at 7 h, not at different culture times. Cells expressed alpha2, alpha3, alpha5, alpha6, alphav, and beta1 subunits. Expression of alpha1, alpha4, alphavbeta3, beta3, beta4, and beta7 was extremely low or was not found. The beta1 integrin expression was higher on the coated than on the noncoated titanium at 3 h, but not on the other studied times. Expression of alpha2, alpha5, alpha6, and alphav expression was found to be upregulated at 24 h compared to earlier culture times on coated titanium, but not on uncoated titanium substrates. From this we conclude that the surface characteristics of a material (roughness and composition) can affect the initial interaction of cells with the material.

Calcium Phosphates↗
PubMed2003

Reactive oxygen species inhibited by titanium oxide coatings.

Titanium is a successful biomaterial that possesses good biocompatibility. It is covered by a surface layer of titanium dioxide, and this oxide may play a critical role in inhibiting reactive oxygen species, such as peroxynitrite, produced during the inflammatory response. In the present study, titanium dioxide was coated onto silicone substrates by radio-frequency sputtering. Silicone coating with titanium dioxide enhanced the breakdown of peroxynitrite by 79%. At physiologic pH, the peroxynitrite donor 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1) was used to nitrate 4-hydroxyphenylacetic acid (4-HPA) to form 4-hydroxy-3-nitrophenyl acetic acid (NHPA). Titanium dioxide-coated silicone inhibited the nitration of 4-HPA by 61% compared to aluminum oxide-coated silicone and 55% compared to uncoated silicone. J774A.1 mouse macrophages were plated on oxide-coated silicone and polystyrene and stimulated to produce superoxide and interleukin-6. Superoxide production was measured by the chemiluminescent reaction with 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (MCLA). Titanium dioxide-coated silicone exhibited a 55% decrease in superoxide compared to uncoated silicone and a 165% decrease in superoxide compared to uncoated polystyrene. Titanium dioxide-coated silicone inhibited IL-6 production by 77% compared to uncoated silicone. These results show that the anti-inflammatory properties of titanium dioxide can be transferred to the surfaces of silicone substrates.

Aluminum↗
PubMed2003

Hydroxylapatite and titanium: interfacial reactions.

The chemical reactions between hydroxylapatite (HA) and titanium were studied in three different kinds of experiments to increase understanding of how to bond HA to titanium for implant materials. HA powder was bonded to a titanium rod with hot isostatic pressing. Interdiffusion of the HA elements and titanium was found in concentration profiles measured in the electron microprobe. Titanium was vapor-deposited on sintered HA discs and heated in air; perovskite (CaTiO(3)) was found on the HA surface with Rutherford backscattering and X-ray diffraction measurements. Powder composites of HA and titanium and TiO(2) were sintered at 1100 degrees C; again, perovskite was a reaction product, as well as beta-Ca(3)(PO(4))(2), from decomposition of the HA. These results demonstrate chemical reactions and interdiffusion between HA and TiO(2) during sintering, resulting in chemical bonding between HA and titanium. Thus, cracks and weakness at HA-titanium interfaces probably result from mismatch between the coefficients of thermal expansion of these materials. HA composites with other ceramics and different alloys should lead to better thermal matching and better bonding at the interface.

Biocompatible Materials↗
PubMed2005

Enhanced intrinsic biomechanical properties of osteoblastic mineralized tissue on roughened titanium surface.

The biological mechanisms underlying bone-titanium integration and biomechanical properties of the integrated bone are poorly understood. This study assesses intrinsic biomechanical properties of mineralized tissue cultured on titanium having different surface topographies. The osteoblastic phenotypes associated with mineral deposition and collagen synthesis underlying the biomechanical modulation are also reported. Rat bone marrow-derived osteoblastic cells were cultured either on the machined titanium disc or acid-etched titanium disc. Nano-indentation study of day 28 culture revealed that the mineralized tissue on the acid-etched surface shows 3-3.5 times greater hardness than that on the machined surface (p < 0.01). Elastic modulus of the mineralized tissue was also 2.5-3 times greater on the acid-etched surface than on the machined surface (p < 0.01). After 28 days of culture, mineralized nodule area was significantly lower on the acid-etched surface than on the machined surface (p = 0.0105), while total calcium deposition did not differ between the two surfaces, indicating denser mineral deposition on the acid-etched surface. Osteopontin and osteocalcin gene expressions assayed by the reverse transcriptase-polymerase chain reaction were upregulated in the acid-etched titanium culture. Collagen synthesis measured by Sirius red stain-based colorimetry was 1.5-10 times higher on the acid-etched surface than on the machined surface in the initial culture period of day 1 to day 14 (p < 0.0001). The amount of collagen synthesis corresponded with the enhanced gene expression of prolyl 4-hydroxylase, a key enzyme for post-translational modification of collagen chains. Scanning electron microscopic images revealed that tissue cultured on the acid-etched titanium exhibited plate-like, compact surface morphology, while the tissue on the machined titanium appeared porous and was covered by fibrous and punctate structures. We conclude that culturing osteoblasts on rougher titanium surfaces enhances hardness and elastic modulus of the mineralized tissue, associated with condensed mineralization, accelerated collagen synthesis, and upregulated expression of selected bone-related genes.

Animals↗
PubMed2005

[Allergic potential of titanium implants].

AIM: The aim of this investigation is to evaluate the allergic potential of titanium and titanium alloys for surgical implant applications. MATERIALS AND METHODS: Discs cut from rods supplied by five different titanium suppliers in several diameters were investigated. The samples were cp-Titanium as well as Ti6Al4 V and Ti6Al7Nb, 6 mm thick with a diameter of between 6 and 60 mm. The material was checked by optical spectral analysis. RESULTS: In all samples except iodidtitanium, a Nickel content of 0.012-0,034 wt% could be detected. CONCLUSION: The low nickel content in the implant material results from the production process. The nickel atoms are in solid solution in the titanium lattice. Nickel allergic patients may develop hypersensitivity reactions even due to this low nickel content. Hence, this reaction may be falsely attributed to the titanium material itself. Measurements of ion concentration in the body are helpful for quantifying the maximum content of nickel in titanium materials for surgical implant applications. In addition, technical questions related to the production of nickel free titanium materials for allergic patients have to be solved.

Biocompatible Materials↗
PubMed1999

Effects of roughness, fibronectin and vitronectin on attachment, spreading, and proliferation of human osteoblast-like cells (Saos-2) on titanium surfaces.

The influence of surface roughness and the presence of adhesion molecules in the culture medium were studied regarding cell adhesion, shape, and proliferation of osteoblast-like cells grown on two types of titanium disk. Type I disks were acid etched and type II disks were sandblasted and acid etched. Surface roughness was determined by contact profilometry and scanning electron microscopy. Chemical composition and oxide thickness of the superficial titanium layer were established with energy dispersive X-ray spectrometry, electron spectroscopy for chemical analysis and auger electron spectroscopy. Titanium release in the culture medium was assessed by inductively coupled plasma-optical emission spectrometry. Osteoblast-like cells (Saos-2) were cultured on both types of titanium disks (1) in standard conditions (DMEM culture medium supplemented with fetal calf serum), (FCS), (2) with the culture medium alone (DMEM alone), (3) in the presence of fibronectin or vitronectin (DMEM supplemented with fibronectin or vitronectin). Cultures were also performed in the presence of monoclonal anti-integrin (beta1, alphav) to test the cell adhesion molecules involved in the cell binding to the titanium surface. We found that sandblasting does not modify the chemical surface composition and that titanium represents only 5-6% (in the atom percentage) of surface elements. Release of titanium in the culture medium was found to increase from 24 to 72 hours. In the absence of FCS, fibronectin, or vitronectin, cells appeared scanty and packed in clusters. On the contrary, cells cultured in the presence of FCS, fibronectin, or vitronectin were flattened with large and thin cytoplasmic expansions. The addition of anti beta1 or alphav integrin subunit monoclonal antibody in the culture medium decreased adhesion and spreading of cells, particularly in the presence of fibronectin. Cell proliferation was significantly higher on culture plastic than on both types of disks, but was increased on rough but not on smooth surfaces. These results indicate that a high surface roughness and presence of fibronectin or vitronectin are critical elements for adhesion, spreading, and proliferation of cells on titanium surfaces.

Antigens, CD↗
PubMed1991

Calcium phosphate naturally formed on titanium in electrolyte solution.

Surface films formed on titanium specimens immersed in electrolyte solutions (pH 4.5, 5.2, 7.4) at 37 degrees C for 1 h, 1 d, 30 d, and/or 60 d, were characterized using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS) to understand the reaction between titanium and inorganic ions. For comparison, the surface of Ti-6AI-4V and Ti-50Ni were also characterized. XPS data revealed that calcium phosphates were naturally formed on these specimens. In particular, compared with the calcium phosphates formed on the titanium alloys, the calcium phosphate formed on titanium immersed for 30 d in the solution with pH 7.4 was more like hydroxyapatite. The compositions of the calcium phosphates formed on the specimens changed with the immersion time and the pH value of the solution. The spectrum obtained using FTIR-RAS from titanium immersed in the solution with pH 7.4 for 60 d was similar to that obtained from carbonate-containing hydroxyapatite. The results indicate that a calcium phosphate similar to apatite is naturally formed on titanium in a neutral electrolyte solution in 30 d. In regard to titanium being a biomaterial, we found this to be an intriguing property. It is possible that this calcium phosphate is responsible for the resulting biocompatibility of titanium.

Alloys↗