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PubMed2005

Electrochemical corrosion and metal ion release from Co-Cr-Mo prosthesis with titanium plasma spray coating.

The corrosion behavior of CoCrMo implants with rough titanium coatings, applied by different suppliers by either sintering or vacuum plasma spraying, has been evaluated and compared with uncoated material. The open-circuit potential, corrosion current and polarization resistance were determined by electrochemical techniques. The Co, Cr and Ti ions released from the samples into the electrolyte during a potentiostatic extraction technique were analyzed using ICP-MS. The Ti coatings from the different suppliers showed a different porous morphology, and the implants exhibited a distinct corrosion activity, underlining the importance of the coating process parameters. Among the titanium coated samples, the one with the sintered overcoat turned out to be the most resistant. Yet, on an absolute scale, they all showed a corrosion resistance inferior to that of uncoated CoCrMo or wrought titanium.

Biocompatible Materials↗
PubMed2005

Mechanical properties and osteoconductivity of porous bioactive titanium.

Porous bioactive titanium implants (porosity of 40%) were produced by a plasma-spray method and subsequent chemical and thermal treatments of immersion in a 5M aqueous NaOH solution at 60 degrees C for 24 h, immersion in distilled water at 40 degrees C for 48 h, and heating to 600 degrees C for 1 h. Compression strength and bending strength were 280 MPa (0.2% offset yield strength 85.2 MPa) and 101 MPa, respectively. For in vivo analysis, bioactive and nontreated porous titanium cylinders were implanted into 6mm diameter holes in rabbit femoral condyles. The percentage of bone-implant contact (affinity index) of the bioactive implants (BGs) was significantly larger than for the nontreated implants (CGs) at all postimplantation times (13.5 versus 10.5, 16.7 versus 12.7, 17.7 versus 10.2, 19.1 versus 7.8 at 2, 4, 8 and 16 weeks, respectively). The percentage of bone area ingrowth showed a significant increase with the BGs, whereas with the CGs it appeared to decrease after 4 weeks (10.7 versus 9.9, 12.3 versus 13.1, 15.2 versus 9.8, 20.6 versus 8.7 at 2, 4, 8 and 16 weeks, respectively). These results suggest that porous bioactive titanium has sufficient mechanical properties and biocompatibility for clinical use under load-bearing conditions.

Animals↗
PubMed2005

Osteoblast adhesion and matrix mineralization on sol-gel-derived titanium oxide.

The biological events occurring at the bone-implant interface are influenced by the topography, chemistry and wettability of the implant surface. The surface properties of titanium alloy prepared by either surface sol-gel processing (SSP), or by passivation with nitric acid, were investigated systematically using X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and contact angle metrology. The bioreactivity of the substrates was assessed by evaluating MC3T3-E1 osteoblastic cell adhesion, as well as by in vitro formation of mineralized matrix. Surface analysis of sol-gel-derived oxide on Ti6Al4V substrates showed a predominantly titanium dioxide (TiO(2)) composition with abundant hydroxyl groups. The surface was highly wettable, rougher and more porous compared to that of the passivated substrate. Significantly more cells adhered to the sol-gel-coated surface, as compared with passivated surfaces, at 1 and 24h following cell seeding, and a markedly greater number of mineralized nodules were observed on sol-gel coatings. Collectively our results show that the surface properties of titanium alloy can be modified by SSP to enhance the bioreactivity of this biomaterial.

3T3 Cells↗
PubMed2005

Stem cell-coated titanium implants for the partial joint resurfacing of the knee.

The goal of the present study was to evaluate the partial surface replacement of the knee with stem cell-coated titanium implants and to provide a basis for a successful treatment of large osteochondral defects. Mesenchymal stem cells (MSCs) were isolated from bone marrow aspirates of adult sheep. Round titanium implants with a diameter of 2 x 7.3 mm were seeded with autologous MSC and inserted into an osteochondral defect in the medial femoral condyle. As controls, defects received either an uncoated implant or were left untreated. Nine animals with 18 defects were sacrificed after 6 months. Histological evaluation was performed by intravital polychrome fluorescent labelling, intravital perfusion with Indian ink, microradiographs and differential staining with toluidine blue. The quality of regenerated cartilage was assessed by in situ hybridization of collagen type II and immunohistochemistry of collagen types I and II. In 50% of the cases, defects treated with MSC-coated implants showed a complete regeneration of the subchondral bone layer. In these cases collagen type II and only traces of collagen type I were detected. A high level of collagen type II mRNA expression compared to articular cartilage indicates regenerating hyaline-like cartilage. A total of 50% of MSC-coated and uncoated implants failed to osseointegrate and formation of fibrocartilage was observed. Untreated defects as well as defects treated with uncoated implants demonstrated incomplete healing of subchondral bone and formation of fibrous cartilage. A modified histological score according to Wakitani significantly demonstrated better results for cell-coated implants (8.8+/-6.4) than for uncoated implants (5.5+/-3.9) and for untreated defects (2.8+/-2.5). Our results demonstrate that, in a significant number of cases, a partial joint resurfacing of the knee with stem cell-coated titanium implants occur. A slow bone and cartilage regeneration and an incomplete healing in half of the MSC-coated implants are limitations of the presented method. To improve our approach and optimize the experimental parameters, further investigations are needed prior to clinical application.

Animals↗
PubMed2006

Bone-like tissue formation using an equine COLLOSS E-filled titanium scaffolding material.

COLLOSS, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE) infection, an equine derived version was investigated in this study, named COLLOSS E. Disc- and tube-shaped implants were made from titanium fibre mesh. The central space of tubes was filled and the discs were impregnated with the COLLOSS E material to assess osteo-induction. These implants and non-loaded controls were implanted subcutaneously into the back of Wistar rats. After implantation periods of 2, 8, and 12 weeks, the implants were retrieved and sections were made. Histology showed a thin fibrous capsule surrounding the titanium mesh and a very mild tissue reaction. The disc implants, loaded or non-loaded, showed no bone formation at all. After 2 weeks of implantation 3 out of 5 of the loaded tubes showed bone formation with a mean of 0.3 mm2 areas of new formed bone, after 8 weeks 3 out of 6 and 0.7 mm2, and after 12 weeks this increased to 6 out of 6 and 1.0 mm2. In the non-loaded tubes only connective tissue in growth was seen. In conclusion, it was demonstrated that COLLOSS E material, loaded in a titanium fibre mesh tube shows osteoinductive properties. The effect of COLLOSS E has to be investigated further in orthotopic sites, which resemble more the final clinical application for bone reconstruction.

Animals↗
PubMed2006

The influence of surface coatings of dicalcium phosphate (DCPD) and growth and differentiation factor-5 (GDF-5) on the stability of titanium implants in vivo.

Mechanical stability of implants is usually tested by pull out or push out tests which destroy the interface between the implant and bone. Pull out tests do not ideally reflect the clinical situation. In contrast, applying submaximal load leads to more physiologic micro-displacement between implant and bone. The aim of this study was to evaluate a new non-destructive mechanical testing device on different modifications of titanium implants. In 18 rabbits we investigated the influence of a dicalcium phosphate (DCPD) coating, or of a growth and differentiation factor-5 (GDF-5) coating, or a combination of both on the stability of titanium implants. The stability of implant was assessed by a non-destructive micro-measurement. In the same specimens the interface was investigated by micro-CT and histological evaluation. Surface modifications had a positive effect on the implant stability regarding displacement (p=0.001). Mechanical stability correlated with the quality of peri-implant tissue. Micro-displacement correlated negatively with the bone formation around the implants in histomorphometric evaluation (p=0.02). Amount of peri-prosthetic soft tissue showed a positive correlation with micro-displacement (p=0.01). Our findings indicate the positive effect of DCPD and GDF-5 coatings on stability of titanium implants. Results demonstrate the non-destructive testing to be an effective method to evaluate mechanical stability of implants.

Adhesiveness↗
PubMed2006

Parathyroid hormone 1-34 enhances titanium implant anchorage in low-density trabecular bone: a correlative micro-computed tomographic and biomechanical analysis.

The use of endosseous titanium implants is the standard of care in dentistry and orthopaedic surgery. Nevertheless, implantation in low-density bone has a poor prognosis and experimental studies show delayed implant anchorage following gonadectomy-induced bone loss. Intermittently administered human parathyroid hormone 1-34 [iahPTH(1-34)] is the leading bone anabolic therapy. Hence, this study assessed whether iahPTH(1-34) enhances titanium implant integration in low-density bone. Threaded titanium implants, 0.9 mm in diameter, were inserted horizontally into the proximal tibial metaphysis of 5-month-old rats, 7 weeks postorchiectomy (ORX). Subcutaneous administration of iahPTH(1-34), at 5, 25 and 75 microg/kg/day commenced immediately thereafter and lasted for 8 weeks. Quantitative micro-computed tomography (muCT) at the implantation site was carried out at 15 microm resolution using high energy and long integration time to minimize artifacts resulting from the high implant radiopacity. Osseointegration (OI) was calculated as percent implant surface in contact with bone (%OI) quantified as the ratio of "bone"-to-total voxels in contact with the implant. Additionally, the trabecular bone volume density (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and connectivity density (Conn.D) were measured in the peri-implant bone. All microCT parameters were stimulated by iahPTH(1-34) dose-dependently; the percent maximal enhancement was %OI = 143, BV/TV = 257, Tb.Th = 150, Tb.N = 140 and Conn.D = 193. The maximal values of %OI, BV/TV and Tb.Th in iahPTH(1-34)-treated ORX rats exceeded significantly those measured in the implantation site of untreated sham-ORX controls. The same specimens were then subjected to pullout biomechanical testing. The biomechanical parameters were also enhanced by iahPTH(1-34) dose-dependently, exceeding the values recorded in the sham-ORX controls. The percent iahPTH(1-34)-induced maximal enhancement was: ultimate force = 315, stiffness = 270 and toughness = 395. Except for the BV/TV and Tb.Th, there was no significant difference between the effect of the 25 and 75 microg/kg/day doses. There was a highly significant correlation between the morphometric and biomechanical parameters suggesting the use of quantitative CT as predictive of the implant mechanical properties. These findings demonstrate that iahPTH(1-34) effectively stimulates implant anchorage in low-density trabecular bone and thus the feasibility of administering iahPTH(1-34) to improve the clinical prognosis in low-density trabecular bone sites.

Animals↗
PubMed2005

Vancomycin covalently bonded to titanium beads kills Staphylococcus aureus.

Periprosthetic infections are life-threatening complications that occur in about 6% of medical device insertions. Stringent sterile techniques have reduced the incidence of infections, but many implant patients are at high risk for infection, especially the elderly, diabetic, and immune compromised. Moreover, because of low vascularity at the site of the new implant, antibiotic prophylaxis is often not effective. To address this problem, we designed a covalent modification to titanium implant surfaces to render them bactericidal. Specifically, we aminopropylated titanium, a widely used implant material and extended a tether by solid phase coupling of ethylene glycol linkers, followed by solid phase coupling of vancomycin. Vancomycin covalently attached to titanium still bound soluble bacterial peptidoglycan, reduced Staphylococcus aureus colony-forming units by 88% +/- 16% over 2 hr, and retained antibacterial activity upon a repeated challenge.

Anti-Bacterial Agents↗
PubMed2006

Light-induced degradation of perfluorocarboxylic acids in the presence of titanium dioxide.

The UV-photon-induced degradation of heptafluorobutanoic acid was investigated in acidic aqueous solutions in the presence of titanium dioxide. Heptafluorobutanoic acid could be degraded with this photocatalyst in a light-induced reaction generating carbon dioxide and fluoride anions. Carbon dioxide evolution in a significant amount occurred only in the presence of molecular oxygen and the photocatalyst. The light-induced degradation of trifluoroacetic acid, pentafluoropropanoic acid, nonafluorobutanoic acid, pentadecafluorooctanoic acid, nonafluorobutanesulfonic acid, and heptadecafluorooctanesulfonic acid in the presence of titanium dioxide was also studied. The perfluorocarboxylic acids under investigation are degraded to generate CO(2) and fluoride anions while both perfluorinated sulfonic acids are persistent under the experimental conditions employed in this study. For all compounds photonic efficiencies of the mineralization reaction were estimated to be smaller than 1x10(-5). To increase the photocatalytic activity mixed systems containing homogeneous phosphotungstic acid and heterogeneous titanium dioxide catalysts were also investigated. In the mixtures of these two photocatalysts, the formation rate of CO(2) increased with illumination time.

Alkanesulfonic Acids↗
PubMed2006

Surface texture and composition of titanium brushed with toothpaste slurries of different pHs.

OBJECTIVES: This in vitro study characterized the surface texture and composition of titanium brushed with toothpaste slurries of different pHs, and thereby elucidated mechanochemical interactions between the metal and abrasive material in dentifrice. METHODS: Two fluoride-free toothpastes, which contained crystalline CaHPO(4).2H(2)O and amorphous SiO(2) particles as abrasive, were mixed with acidic buffers to provide slurries of pH 6.8 and 4.8. Specimens were cast from CP Ti, mirror-polished, and then toothbrushed at 120strokes/min for 350,400 strokes under a load of 2.45N. Specimen surfaces were characterized by means of SPM and EPMA. The obtained data were compared with the already reported results of water-diluted alkaline slurries. SPM data of each paste were analyzed using one-way ANOVA, followed by post hoc Tukey test. RESULTS: Irrespective of toothpaste, neutral slurries, as with alkaline slurries, yielded a chemically altered surface with rough texture, whereas acidic slurries formed a chemically clean surface with relatively smooth texture. Mechanochemical polishing effect might be mainly responsible for the cleanness and smoothness. SIGNIFICANCE: Acidic slurry-induced smooth surface may minimize plaque formation. However, the augmentation of released titanium ions may be adverse to the human body. For evaluation of toothpaste abrasion effects on titanium, paste slurry pH should be taken into account.

Acids↗
PubMed2006

The effect of shot blasting and heat treatment on the fatigue behavior of titanium for dental implant applications.

OBJECTIVES: The effect of shot blasting treatment on the cyclic deformation and fracture behavior of a commercial pure titanium with two different microstructures; equiaxed (alpha-phase) and acicular (martensitic alpha'-phase) was investigated. METHODS: Fatigue tests were carried out in artificial saliva at 37 degrees C. Cyclic deformation tests were carried out up to fracture and fatigue crack nucleation and propagation were analysed. Residual stresses were determined by means of X-ray diffraction. RESULTS: The results show that shot blasting treatment improves fatigue life in the different microstructures studied. The equiaxed phase has improved mechanical properties compared to the acicular one. Despite the fact that control of the variables of shot blasting is not precise because of the nature of the treatment, it improves the fatigue life by the fact that the initiation site of the fatigue crack changes from the surface of the specimen to the interior of the shot blasted specimen. This is a consequence of the layer of compressive residual stresses that the treatment generates on titanium surfaces. The acicular morphology of the martensite favors crack propagation along the interface of the alpha' plates. SIGNIFICANCE: Shot blasting, which is widely used on titanium dental implants in order to favour their osseointegration, can also improve their fatigue resistance.

Compressive Strength↗
PubMed2006

Surface treatments of titanium dental implants for rapid osseointegration.

The osseointegration rate of titanium dental implants is related to their composition and surface roughness. Rough-surfaced implants favor both bone anchoring and biomechanical stability. Osteoconductive calcium phosphate coatings promote bone healing and apposition, leading to the rapid biological fixation of implants. The different methods used for increasing surface roughness or applying osteoconductive coatings to titanium dental implants are reviewed. Surface treatments, such as titanium plasma-spraying, grit-blasting, acid-etching, anodization or calcium phosphate coatings, and their corresponding surface morphologies and properties are described. Most of these surfaces are commercially available and have proven clinical efficacy (>95% over 5 years). The precise role of surface chemistry and topography on the early events in dental implant osseointegration remain poorly understood. In addition, comparative clinical studies with different implant surfaces are rarely performed. The future of dental implantology should aim to develop surfaces with controlled and standardized topography or chemistry. This approach will be the only way to understand the interactions between proteins, cells and tissues, and implant surfaces. The local release of bone stimulating or resorptive drugs in the peri-implant region may also respond to difficult clinical situations with poor bone quality and quantity. These therapeutic strategies should ultimately enhance the osseointegration process of dental implants for their immediate loading and long-term success.

Biomimetic Materials↗
PubMed2005

Rigid internal fixation with titanium versus bioresorbable miniplates in the repair of mandibular fractures in rabbits.

The purpose of this study was to compare by qualitative histology the efficacy of rigid internal fixation with titanium system and the Lacto Sorb system in mandibular fractures in rabbits. Thirty male adult rabbits Oryctolagus cuniculus were used. Unilateral mandibular osteotomies were performed between the canine and first premolar. The animals were divided into two groups: for Group I-rigid internal fixation was performed with titanium system 1.5 mm (Synthes, Oberdorf, Switzerland), with two screws of 6 mm (bicortical) on each side of the osteotomy. For Group II-rigid internal fixation was performed with PLLA/PGA system 1.5 mm (Lacto Sorb, WLorenz, Jacksonville, FL, USA). The histological analysis evaluated the presence of inflammatory reaction, degree of bone healing and degree of resorption of the Lacto Sorb screws. The results of both fixation systems were similar, only with a small difference after 15 and 30 days. In Group I a faster bony healing was noted. But after 60 days, bony healing was similar in both groups. It is concluded that both PLLA/PGA and titanium plates and screws provide sufficient strength to permit mandibular bone healing. The resorption process of PLLA/PGA osteosynthesis material did not cause acute or chronic inflammatory reaction or foreign body reaction during the studied period.

Absorbable Implants↗
PubMed2006

Individually preformed titanium mesh implants for a true-to-original repair of orbital fractures.

The purpose of this investigation is to present the results using preoperatively-formed titanium mesh implants for a true-to-original primary repair of extensive orbital floor and medial wall fractures. Individually preformed implants were used to repair extensive orbital floor injuries in 19 patients at the University Hospital, Freiburg. The form of the orbital floor and walls was analysed by preoperative diagnostic CT scan data. The form of the virtual reconstructed orbit was transformed into a model of the orbital cavity by a template machine. Postoperative imaging by or CT scan verified the exact 3D reconstruction of the orbital cavity 'true to original'. None of the patients demonstrated diplopia or enophthalmos postoperatively. Using individually preformed titanium mesh implants, the accuracy of the 3D orbital reconstruction was within a range of 1mm. The reconstruction using preformed implants proved to be less time consuming, more precise and less invasive, compared to 'free hand' efforts, for the repair of orbital injuries using titanium mesh and calvarial grafts.

Biocompatible Materials↗
PubMed2006

Granulomatous reaction to titanium alloy: an unusual reaction to ear piercing.

A 68-year-old man presented with 4 firm, flesh-colored, and slightly erythematous nodules located on the superior pole and lobule of each ear. Although reluctant to provide details, it was discovered he had pierced his ears approximately 10 years earlier, and the nodules developed at the sites of the piercings. Keloids were suggested clinically and the lesions were excised. Microscopic examination demonstrated epithelialized tracts surrounded by a granulomatous infiltrate of macrophages, lymphocytes, and plasma cells. Closer examination revealed minute brown-black particles within macrophages. Dark-field microscopy confirmed the metallic nature of the particles. Environmental scanning electron microscopy with energy dispersive spectroscopy revealed the particles to be composed of titanium, aluminum, and vanadium. It would appear that in rare circumstances titanium alloy used in body piercing may engender a granulomatous dermatitis. The rarity of such a response to titanium alloy is discussed and the literature appraised.

Aged↗
PubMed2006

Influence of water, loading rate and bonder on the adhesion of porcelain to titanium.

OBJECTIVES: The aim of this study was to measure the influence of water on the adhesion between titanium and porcelain by means of the strain energy release rate (G-value or interfacial toughness). METHODS: Rectangular specimens of grade II titanium and a reference gold-palladium porcelain fused to metal (PFM) alloy were veneered with feldspathic porcelains. In the case of the titanium, two gold and one ceramic bonder systems were used to enhance the adhesion of the porcelain. The G-value was measured with a four-point bending configuration developed by Charalambides et al. (Journal of Applied Mechanics (Trans ASME). 1989;56:77-82), at four different loading rates (from 0.1 to 15 N/s) in water and at one loading rate (1.5 N/s) in kerosine. RESULTS: There was a significant difference (ANOVA, p<0.01) in the interfacial toughness between the different bonding systems, with the two goldbonder systems exhibiting higher toughness in kerosine and water than the ceramic bonder. The two goldbonders achieved the best results across all loading rates. Their interfacial toughness, tested in kerosine, varied between 45.83+/-6.72 and 73.54+/-17.01 J/m(2) and tested in water from 40.86+/-2.23 to 69.17+/-12.33 J/m(2), respectively. The ceramic Ti bonder achieved the lowest G-values throughout (30.15+/-5.52 J/m(2) in kerosine to 11.08+/-2.18 J/m(2) in water). The gold-palladium PFM alloy showed more constant behaviour (33.48+/-2.24 J/m(2) to 23.07+/-0.53 J/m(2) in kerosine and water, respectively). CONCLUSION: Compared to the gold-palladium PFM alloy, the goldbonders achieved much higher G-values whereas the ceramic Ti bonder G-values were lower when tested in water and in kerosine.

Adhesiveness↗
PubMed2006

The effect of three silane coupling agents and their blends with a cross-linker silane on bonding a bis-GMA resin to silicatized titanium (a novel silane system).

OBJECTIVES: Three activated organofunctional silane coupling agents alone and blended with a non-functional cross-linker silane were evaluated as adhesion promoters in an experiment where a bis-GMA (bis-phenol-A-diglycidyldimethacrylate) resin was bonded to silicatized titanium. The adhesive performances of the silanes were assessed as shear bond strength values. MATERIALS AND METHODS: 3-Methacryloyloxypropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine and [3-(triethoxysilyl)propyl]urea were prepared as 1.0vol.% solutions in 95 vol.% ethanol. They were each also blended with 1.0 vol.% 1,2-bis-(triethoxysilyl)ethane solutions that were activated for 1 or 24 h. Titanium slides were cleaned, silicatized, distributed randomly to study groups and silanized with nine silane solutions. After silanization experimental bis-GMA resin stubs were photo-polymerized and post-polymerized in a light-curing unit. The shear bond strength was measured as 'dry samples' and after thermo-cycling (6000 cycles at 5-55 degrees C). RESULTS: The type of silane affected significantly the shear bond strength (p<0.001) and the use of cross-linker silane (p<0.005) according to the statistical analysis (ANOVA). It showed that the highest shear bond strength for thermo-cycled resin stub samples (n=8/group) was obtained with a blend of 1.0vol.% 3-methacryloyloxypropyltrimethoxysilane+1.0 vol.% 1,2-bis-(triethoxysilyl)ethane blend (10.4+/-3.5 MPa). The lowest results were obtained with 1.0 vol.% [3-(triethoxysilyl)propyl]urea (4.5+/-1.0 MPa), and with 1.0 vol.% N-[3-(trimethoxysilyl)propyl]ethylenediamine (4.5+/-1.4 MPa). CONCLUSIONS: Silanization with a blend of a functional silane and a cross-linker silane (a novel silane system) might improve the hydrolytic stability of a siloxane film between silicatized titanium and a bis-GMA resin.

Analysis of Variance↗
PubMed2004

Methoxy-phenyl substituted ansa-titanocenes as potential anti-cancer drugs derived from fulvenes and titanium dichloride.

Starting from 6-(4'-methoxyphenyl)fulvene (1a), 6-(2',4',6'-trimethoxyphenyl)fulvene (1b), or 6-(3',5'-dimethoxyphenyl)fulvene (1c), [1,2-di(cyclopentadienyl)-1,2-di(4'-methoxyphenyl)-ethanediyl] titanium dichloride (2a), [1,2-di(cyclopentadienyl)-1,2-bis(2',4',6'-trimethoxyphenyl)-ethanediyl] titanium dichloride (2b), and [1,2-di(cyclopentadienyl)-1,2-bis(3',5'-dimethoxyphenyl)-ethanediyl] titanium dichloride (2c) were synthesised. When titanocenes 2a-c were tested against pig kidney carcinoma cells (LLC-PK) inhibitory concentrations (IC50) of 2.8 x 10(-4), 3.6 x 10(-4) and 2.1 x 10(-4) M, respectively, were observed.

Animals↗