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PubMed2001

Bond strength of binary titanium alloys to porcelain.

The purpose of this study was to investigate the bond strength between porcelain and experimental cast titanium alloys. Eleven binary titanium alloys were examined: Ti-Cr (15, 20, 25 wt%), Ti-Pd (15, 20, 25 wt%), Ti-Ag (10, 15, 20 wt%), and Ti-Cu (5, 10 wt%). As controls, the bond strengths for commercially pure titanium (KS-50, Kobelco, Japan) and a high noble gold alloy (KIK, Ishifuku, Japan) were also examined. Castings were made using a centrifugal casting unit (Ticast Super R, Selec Co., Japan). Commercial porcelain for titanium (TITAN, Noritake, Japan) was applied to cast specimens. The bond strengths were evaluated using a three-point bend test according to ISO 9693. Since the elastic modulus value is needed to evaluate the bond strength, the modulus was measured for each alloy using a three-point bend test. Results were analyzed using one-way ANOVA/S-N-K test (alpha = 0.05). Although the elastic moduli of the Ti-Pd alloys were significantly lower than those of other alloys (p = 0.0001), there was a significant difference in bond strength only between the Ti-25Pd and Ti-15Ag alloys (p = 0.009). The strengths determined for all the experimental alloys ranged from 29.4 to 37.2MPa, which are above the minimum value required by the ISO specification (25 MPa).

Dental Alloys↗
PubMed2001

Influence of surface modifications to titanium on antibacterial activity in vitro.

The antibacterial effect of surface modifications to titanium on Porphyromonas gingivalis ATCC 33277 and Actinobacillus actinomycetemcomitans ATCC 43718 was evaluated. Surface modifications were performed with dry processes including ion implantation (Ca+, N+, F+), oxidation (anode oxidation, titania spraying), ion plating (TiN, alumina), and ion beam mixing (Ag, Sn, Zn, Pt) with Ar+ on polished pure titanium plates. F+-implanted specimens significantly inhibited the growth of both P. gingivalis and A. actinomycetemcomitans than the polished titanium. The other surface-modified specimens did not exhibit effective antibacterial activity against both bacteria. No release of the fluorine ion was detected from F-implanted specimens under dissolution testing. This result and the characterization of the F+-implanted surfaces suggested that the possible antibacterial mechanism of the F+-implanted specimen was caused by the formation of a metal fluoride complex on the surfaces. In addition, F+-implanted surfaces did not inhibit the proliferation of fibroblast L929-cells. These findings indicate that surface modification by means of a dry process is useful in providing antibacterial activity of oral bacteria to titanium implants exposed to the oral cavity.

Aggregatibacter actinomycetemcomitans↗
PubMed2002

Effects of fluoride concentration and elastic tensile strain on the corrosion resistance of commercially pure titanium.

The corrosion resistance of commercially pure (CP) titanium in 1% NaCl + 0 approximately 1% NaF solution (pH = 6) under different elastic tensile strains was investigated by using electrochemical impedance spectroscopy (EIS) measurement technique. The polarization resistance (Rp), which is inversely proportional to the corrosion rate, of CP titanium in the test solution was obtained from the EIS data. Different elastic tensile strains, namely 0%, 1%, 2%, and 4%, were applied on the test specimens by using a tensile test machine during the corrosion tests. Corrosion morphology was characterized by using a scanning electron microscope. Surface chemical analyses were performed by using energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The results showed that the NaF concentration and the elastic tensile strain had a statistically significant influence on the Rp (P<0.001). The Rp decreased on increasing the NaF concentration and the elastic tensile strain. When the NaF concentration was lower than 0.10%, the Rp value (> 3.4 x 10(5) omega cm2) was mainly ascribed to the formation of a protective titanium dioxide (TiO2) on the metal surface, regardless of the elastic tensile strain applied. However, when the NaF concentration was higher than 0.1%, the protectiveness of TiO2 was destroyed by fluoride ions, leading to severe corrosion of CP titanium.

Corrosion↗
PubMed2002

Interaction of calcium and phosphate in apatite coating on titanium with serum albumin.

A Ca-deficient carbonate apatite coating on titanium was prepared by pre-calcifying titanium in a saturated Ca(OH)2 solution and then immersing in a supersaturated calcium phosphate solution. The interaction of the protein with the apatite coating on titanium was investigated by scanning electron microscopy with X-ray energy dispersion spectroscopy. X-ray photoelectron spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. During immersion of the coating in bovine serum albumin (BSA) solution, accompanied by an adsorption of BSA onto the coating, calcium and phosphate ions dissolved and reprecipitated, resulting in the formation of the coating containing BSA from the surface to subsurface layers. The adsorption modified the structure and morphology of the apatite coating on titanium and changed the protein configuration. It was also found that the protein chemically adsorbed onto surfaces containing calcium or phosphorus, showed that both Ca and P on the apatite coating were the binding sites with protein. The BSA adsorption onto the coating involved several elements and groups. In this process. Ca played an essential role, and the interaction of Ca on the apatite coating with the protein stimulated the bond of the protein at P sites.

Animals↗
PubMed2002

Initial interaction of rat bone marrow cells with non-coated and calcium phosphate coated titanium substrates.

Initial interactions of rat bone marrow (RBM) cells with smooth titanium, rough titanium or calcium phosphate coated substrates were tested. Cells were seeded onto the substrates, and attachment, integrin expression and spreading and morphology were studied. We found no difference in attachment of RBM cells to the different materials. We did find differences in the percentage of attached cells within a certain time between replicate runs of the experiments. RBM cells on all materials express alpha1, alpha3, alpha5, alpha6 and beta1 subunits. Again there was a large difference in expression patterns on RBM cells in different runs. No difference was found in expression on the various materials. For alpha1, alpha5, alpha6 and beta1, no difference was found in expression between attached and unattached cells. Expression of alpha3 was similar on attached and unattached cells during early culture. At the end of culture, alpha3 expression was downregulated for attached cells and not for unattached cells. This resulted in a higher expression of alpha3 for unattached cells compared to attached cells. Cells did spread on all materials, and reached a larger cell size on smooth titanium than on the rough materials. Morphology of the cells on the materials differed. On smooth titanium, cells usually showed a compact cell body with short cellular extensions. On the rough materials, cells often showed elongated shapes, with many thin cellular extensions. From this we conclude that the substrate surface characteristics of the materials we used do not influence attachment or integrin expression during the initial cell-material interactions. On the other hand, spreading behavior and cell morphology do depend on substrate surface characteristics.

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↗
PubMed2003

Residual aluminum oxide on the surface of titanium implants has no effect on osseointegration.

The cleanliness of titanium dental implants surfaces is considered to be an important requirement for achieving osseointegration, and it has been hypothesized that the presence of inorganic contaminants could lead to lack of clinical success. Aluminum ions are suspected to impair bone formation by a possible competitive action to calcium. The objective of the present study was to describe the effects of residual aluminum oxide particles on the implant surface on the integration of titanium dental implants as compared to decontaminated implants in a rabbit experimental model. Threaded screw-shaped machined grade 3 c.p. titanium dental implants, produced with high-precision equipment, were used in this study. The implants were sandblasted with 100-120 microm Al2O3 particles at a 5atm pressure for 1min, then 24 implants (control implants) underwent ASTM F 86-68 decontamination process in an ultrasonic bath. The other 24 implants (test implants) were washed in saline solution for 15min. Both test and control implants were air-dried and sterilized at 120 degrees C for 30min. After sterilization the implants were inserted into the tibiae (two test and two control implants in each rabbit). Twelve New Zealand white mature male rabbits were used in this study. The protocol of the study was approved by the Ethical Committee of our University. No complications or deaths occurred in the postoperative period. All animals were euthanized, with an overdose of intravenous pentobarbital, after 4 weeks. A total of 48 implants were retrieved. The images were analyzed for quantitation of percentage of surface covered by inorganic particles, bone-implant contact, multinucleated cells or osteoclasts in contact with the implant surface and multinucleated cells or osteoclasts found 3mm from the implant surface. The differences in the percentages between the two groups have been evaluated with the analysis of variance. The implant surface covered by inorganic particles on test implants was significantly higher than that of control implants (p=0.0000). No statistically significant differences were found in the bone-implant contact percentages of test and control implants (p=0.377). No statistically significant differences were found in the number of multinucleated cells and osteoclasts in contact with the implant surface (p=0.304), and at a distance of 3mm from the implant surface (p=0.362). In conclusion, our histological results do not provide evidence to support the hypothesis that residual aluminum oxide particles on the implant surface could affect the osseointegration of titanium dental implants.

Aluminum Oxide↗
PubMed2003

Surface modifications induced by ns and sub-ps excimer laser pulses on titanium implant material.

Medical implants used in oral and orthopaedic surgery are mainly produced from titanium. Their biological behaviour, e.g. osseointegration, essentially depends on both the chemical composition and the morphology of the surface. Modifications achieved by excimer laser irradiation of titanium samples were investigated in order to improve their surface characteristics so as to facilitate biointegration. To enlarge the effective interfacial area of bone-implant contact, holes were ablated by laser pulses of ns or sub-ps length. During ns ablation, crown-like projecting rims formed around the borders of the holes. Ultra-short (0.5ps) KrF excimer laser pulses were successfully applied to avoid these undesirable formations. Since a smooth dental implant surface is necessary to maintain a healthy connection with the soft tissues, laser polishing of samples was investigated, too. Irradiation with a series of ns laser pulses resulted in effective smoothing, as measured with atomic force microscope. X-ray photoelectron spectroscopy analysis of the laser-polished titanium surface revealed that laser treatment led to a decrease of the surface contamination and in thickening of the oxide layer. X-ray diffraction measurements demonstrated that the original alpha-titanium crystal structure was preserved.

Biocompatible Materials↗
PubMed2003

Chondrocyte interactions with porous titanium alloy and calcium polyphosphate substrates.

Chondrocytes maintain their phenotype and form cartilagenous tissue when cultured on calcium polyphosphate (CPP) or titanium alloy (Ti alloy), porous three-dimensional materials. To understand how these materials may influence chondrocyte phenotype and matrix synthesis, the early interactions of cultured cells with CPP and titanium alloy were examined. These were compared to chondrocytes grown in monolayer culture on tissue culture polystyrene, conditions in which cultured chondrocytes dedifferentiate and do not form cartilagenous tissue. Scanning electron microscopy of cells up to 72 h in culture showed that bovine chondrocytes on CPP, Ti alloy, and polystyrene were an admixture of round and spread cells. The spread cells on CPP and titanium alloy were not entirely flattened but maintained a polygonal shape. In contrast, spread chondrocytes in monolayer culture were flatter and significantly larger, a difference that was maintained even in the absence of serum. All cells cultured on CPP and Ti alloy exhibited subcortical ring-like distribution of actin filaments whereas the flattened cells on polystyrene showed actin filaments distributed throughout the cytoplasm. Cells on CPP and Ti alloy synthesized significantly less collagen and proteoglycans than cells cultured on polystyrene at 72 h of culture. In summary the cells on the porous three-dimensional materials differed from those on polystyrene in terms of cell morphology and size, actin cytoskeleton organization, and synthesis of selected matrix macromolecules. The data suggests that CPP and titanium alloy may mediate their effect by limiting cell spreading in part by favoring the maintenance of a ring-like actin distribution.

Actin Cytoskeleton↗
PubMed2004

Nanotexturing of titanium-based surfaces upregulates expression of bone sialoprotein and osteopontin by cultured osteogenic cells.

Bone formation around implants is influenced by surface geometry. Since cell/matrix/substrate interactions associated with cell signaling occur in the nanoscale dimension, we have evaluated the influence of nanotexturing of titanium-based surfaces on the expression of matrix proteins by cultured osteogenic cells at initial time points. Cells were obtained by enzymatic digestion of newborn rat calvaria and grown on titanium and titanium alloy discs with nanotextured or machined surfaces, and on glass coverslips for periods of 6 h, 1 day, and 3 days, under standard culture conditions. Cultures were processed for single or dual immunolabeling with monoclonal and/or polyclonal antibodies against bone sialoprotein (BSP), fibronectin (FN), osteopontin (OPN), type-I pro-collagen, or tubulin, followed by corresponding fluorophore-conjugated secondary antibodies. Some samples were processed for scanning electron microscope analysis of morphology and immunogold labeling. After 6 h, nanotextured surfaces exhibited up to a nine-fold increase in the proportion of cells with peripheral OPN labeling. At day 3, the proportion of OPN and BSP labeled cells was higher, and the intensity of immunoreactivity dramatically increased. No significant differences were observed in the expression pattern and the proportion of cells immunoreactive for FN or type-I pro-collagen. Our results demonstrate that nanotexturing of titanium-based surfaces upregulates the early expression of BSP and OPN in osteogenic cell cultures.

Alloys↗
PubMed2004

Composition of surface oxide film of titanium with culturing murine fibroblasts L929.

Changes in the composition of surface oxide film on titanium specimens in the presence of amino acids, serum proteins, and cells were characterized using X-ray photoelectron spectroscopy. The surface oxide film on titanium formed in the air is so protective that the further oxidation of titanium is prevented in various circumstances. During immersion of the specimen in Hanks' solution, Eagle's minimum essential medium (MEM), and MEM with the addition of fetal bovine serum (MEM+FBS), calcium phosphate precipitated, causing the increase in thickness of the surface oxide film. Calcium phosphate was also precipitated with culturing murine fibroblast L929, but the amount of the calcium phosphate was smaller than those in Hanks' solution, MEM, and MEM+FBS. The relative concentration ratio of calcium to phosphorous, [Ca]/[P], increased with proteins charging negatively, while the ratio decreased with the cells whose extracellular matrix charging positively. In addition, sulfur precipitated as S(0) and/or S(2-) only with culturing the cells. Sulfate ions in the MEM+FBS are reduced at the interface between titanium and the solution with the existence of cells.

Adsorption↗
PubMed1997

Fast precipitation of calcium phosphate layers on titanium induced by simple chemical treatments.

A simple two-step chemical treatment, i.e. etching with HCl and H2SO4 followed by immersion in boiling dilute NaOH solution, has been developed by our group to prepare bioactive microporous titanium surfaces allowing fast deposition of a calcium phosphate layer (CPL) from an in vitro supersaturated calcification solution (SCS). In this work, a precalcification (Pre-Ca) procedure was applied by soaking the two-step treated titanium in Na2HPO4 and then saturated Ca(OH)2 solution before immersion in SCS to accelerate further the CPL precipitation. The treated titanium surfaces with Pre-Ca were characterized after 1, 2, 4, 8 and 16 h of immersion in SCS by means of scanning electron microscopy together with energy dispersive X-ray analysis, X-ray diffraction and infrared absorption analysis. It was observed that the CPL precipitation rate with Pre-Ca averaged 1 microm h-1, twice as fast as without Pre-Ca. No precipitation was observed on untreated titanium with Pre-Ca up to day 14 of immersion in the SCS.

Calcium Hydroxide↗
PubMed1999

Cell surface characteristics of microbiological isolates from human percutaneous titanium implants in the head and neck.

Percutaneous implants are commonly associated with several problems, and different failure modes have been described. Infections constitute one serious complication which may lead to the removal of the implant. In contrast to infections around polymer implants, infections around skin-penetrating titanium implants anchored in the temporal bone are often cured by local treatment. Coagulase-negative staphylococci are the most common etiological agents in infections related to polymers whereas Staphylococcus aureus is considered as the main pathogen in infections around metallic implants. Microbial adhesion is a prerequisite for an infection. In the present study, the cell surface of microbes isolated from the skin around skin-penetrating titanium implants, with and without signs of infection, was characterized with respect to expression of cell surface hydrophobicity and to binding of immobilized fibronectin, vitronectin and collagen type 1 which could mediate adhesion. Expression of protein binding was similar in strains isolated from the two groups. No strain expressed a hydrophobic cell surface as determined by two-phase separation, and we conclude that the microenvironment around a titanium implant promotes expression of a hydrophilic rather than a hydrophobic cell surface which in turn makes many infections around a titanium implant curable by local treatment.

Bacteria↗
PubMedDate not supplied

Effect of mandibular titanium reconstructive plates on radiation dose.

BACKGROUND: The effects of the mandibular titanium alloy plates on the radiation-tissue interactions are not clearly defined. Photon beam radiation may be modified after striking a metal plate used to reconstruct the mandible after oncologic surgery. The purpose of this study was to determine, in a human mandible model, the effects of a titanium alloy plate on the radiation dose received at the bone/titanium (plate and screws) interface and bone/soft tissue interface. METHODS: We used an adult male human head and neck ex vivo model. A medical grade titanium alloy 6-hole plate, 2.4 mm, was fixed in the midline of the mandible. The mandible was then irradiated using 6 MV photon beams. Thermoluminescent dosimeters were used to measure the radiation doses anterior and posterior to the mandible. The experiment was then repeated without the plate and screws. RESULTS: The difference between the average doses received by the mandible reconstructed with plate/screws and a mandible without plate/screws was +2.1% at the buccal aspect of the mandible and +3.0% at the lingual aspect; respective P values were.741 and .323. Thus, these differences were not statistically significant. CONCLUSION: In this study, we did not observe any significant influence of titanium alloy plate/screws on the radiation doses received by tissues anterior or posterior to the mandible.

Adult↗
PubMed1996

Effects of multiple sterilization on surface characteristics and in vitro biologic responses to titanium.

PURPOSE: This study evaluates the surface changes and effects on in vitro cell attachment and spreading brought about on prepared commercially pure titanium by multiple exposures to common sterilization methods. MATERIALS AND METHODS: Discs of commercially pure titanium were prepared to approximate the surface roughness of commercially available bone miniplates. Samples underwent sterilization by exposure to ultraviolet light; ethylene oxide sterilization (1, 5, or 10 cycles); or by steam autoclaving (1, 5, or 10 cycles). Representative surfaces from these sterilization groups were examined using a series of surface analytical techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and contact angle measurements. Cell attachment assays using murine fibroblasts were then performed on titanium surfaces from each sterilization group and on tissue culture plastic controls. Sterilized surfaces contained O, C, and N contaminants, which affected surface energetics. Mean percent cell attachment values for each group were obtained for periods of up to 1 hour. Representative samples from each group were examined using SEM to ascertain cell spreading and morphology for each sterilization group. RESULTS: Ultraviolet (UV) sterilized surfaces showed no changes from the unsterilized state macroscopically or under SEM. UV surfaces showed cell attachment levels similar to control surfaces at all intervals, and a chronologic progression of cell spreading. Ethylene oxide-sterilized surfaces showed occasional bluish discoloration and a microscopic particulate contaminant, resulting in modest decreases in cell attachment levels without strong correlation to numbers of sterilization cycles. Autoclaved surfaces generally showed the greatest discoloration and heaviest particulate contamination. Cell attachment levels were lower, and cell spreading was diminished compared with the ethylene-oxide-treated group. CONCLUSIONS: Both ethylene oxide and steam autoclave sterilization contaminated and altered the titanium surface, resulting in decreased levels of cell attachment and spreading in vitro. Although corroborative in vivo experiments should be conducted, the results of this study indicate that some multiple sterilization regimens for metallic materials may pose serious biologic concerns.

3T3 Cells↗
PubMed1997

Dentists' opinions on aspects of cast titanium restorations.

OBJECTIVES: The purpose of this paper was to study dentists' opinions regarding aspects of the clinical use of cast titanium restorations. METHODS: Since 1988 more than 10,000 cast titanium units of crowns and fixed partial dentures have been produced by the only dental laboratory that produces cast titanium restorations in Norway. A questionnaire on the clinical behaviour of such restorations was mailed to all 72 dental practitioners who were recorded in the computer file of this laboratory. RESULTS AND CONCLUSION: In the opinion of the 64 dental practitioners who completed the questionnaire, cast titanium is a useful supplement to conventional casting alloys, particularly because of its favourable cost. It has a satisfactory clinical behaviour, although there may be some problems related to technical and aesthetic aspects.

Attitude of Health Personnel↗
PubMed1981

The reactions of bone, connective tissue, and epithelium to endosteal implants with titanium-sprayed surfaces.

The results of a research project which has been under way for the last 7 years are reported. The project has been centred around a series of animal (monkey) experiments designed to test the suitability of cylindrical titanium implants with titanium-sprayed surfaces. The following results have been obtained: 1. The bone applies itself "ankylotically" (i.e. without an intervening layer of connective tissue) to the surface of the implant and, as revealed by observation over periods of up to 1 3/4 years, even remains attached to the implant surface when placed under load. 2. The fibres of the connective tissue between the bone and the epithelium insert into the titanium-sprayed surface and appear to be functionally orientated. 3. If the post of the implant is situated in a region of immobile, keratinized mucosa signs of adhesion of the epithelial cells to the titanium-sprayed surface become apparent. 4. The clinical success of the implant is clearly dependent on (a) the presence of tethered, immobile mucosa ("gingiva") around the post of the implant, and (b) perfect oral hygiene.

Animals↗
PubMed2002

Macrophage exposure to particulate titanium induces phosphorylation of the protein tyrosine kinase lyn and the phospholipases Cgamma-1 and Cgamma-2.

A frequent long-term complication of total joint arthroplasty is aseptic loosening, the end result of wear debris production, synovial macrophage activation, inflammatory mediator release, and osteolysis about the implant-bone or cement-bone interface. To elucidate the mechanisms of particle-induced macrophage activation and mediator production, we studied early signal transduction events using J774A.1 macrophages and 3 microm titanium particles. Treating macrophages with herbimycin A or genistein, two inhibitors of protein tyrosine kinases (PTKs), inhibited titanium phagocytosis as well as secretion of tumor necrosis factor-alpha (TNF-alpha) and prostaglandin-E2 (PGE2) in a dose-dependent manner. Both processes therefore depend on a PTK signaling cascade. Specifically, macrophage exposure to titanium-induced phosphorylation of multiple proteins including the Src kinase Lyn and phospholipase Cgamma-1 and Cgamma-2. Phosphorylation peaked within 2 min and returned to baseline within 45 min. Similar but not identical phosphorylation patterns were obtained when cells were stimulated with titanium preincubated with serum or albumin, suggesting distinct signal transduction pathways dependent on particle coating.

Cell Line↗