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PubMed1997

[Observations on before and after employ of screw of implant denture with SEM].

The loss of screw is one of the clinic complication in MDIC implant denture cases. The purpose of this study is to find the cause of loss of screw. The authors has studied MDIC implant denture with SEM before and after employ of the screw and found that the causes of screw loss were crevice corrosion and friction pressure. Crevice corrosion may promote the loss of screw. Base the above condition, it is necessary to select Ti-alloy screw and associat with anticorrosive measure in MDIC implant denture construction.

Corrosion↗

PubMed2003

Metallic biomaterials TiN-coated: corrosion analysis and biocompatibility.

Corrosion processes due to contact with the physiological environment should be avoided or minimized in orthopedic implants. Four metallic substrates frequently used as biomaterials: pure Ti, Ti-6Al-4V alloy, ASTM F138 stainless steel, and Co-Cr-Mo alloy, were coated with TiN using the physical vapor deposition (PVD) technique. These coatings have been screened by polarization curves in physiological solutions. TiN prepared by PVD is efficient as coating for stainless steel. On titanium and alloy there are no benefits concerning the corrosion resistance compared to the bare Ti-materials. TiN coatings have been screened according to ISO 10993 standard tests for biocompatibility and exhibited no cytotoxicity, dermal irritation, or acute systemic toxicity response.

Alloys↗

PubMed2001

In vitro kinetic evaluation of titanium alloy biodegradation.

The present controlled in vitro experiment evaluated the dissolution kinetics of titanium (Ti), aluminum (Al) and vanadium (V). Titanium alloy (Ti90Al6V4) dental implants were inserted in 1.8 ml sterile tubes, containing equal volumes of NaCl 0.9% (w/v) and human serum. Metallic elements released by the atomic process of corrosion were measured at pH 7.2 and 37 C by atomic absorption spectrophotometer at 1, 3, 6, 9, 15, 21, 27, 33, 42, 51, 60, 69, 78, 87 and 96 days. Ti dissolution averaged 16+/-5 ng/cm2/day and 1565 ng/cm2 over the experimental period. Al dissolution was stable at 9+/-5 ng/cm2/day and averaged 945 ng/cm2 over the 96-day period. V dissolution was stable at 0.15+/-0.18 ng/cm2/day after the sixth day of incubation and averaged 42 ng/cm2 over the 96-day period. Major disparities in atomic dissolution were detected among implants. No local or systemic reaction to titanium has been documented. In contrast, 4% toxic V and 6% Al may suffice to elicit local and systemic reactions or inhibit cellular proliferation and differentiation.

Alloys↗

PubMed2001

Proliferation and differentiation parameters of human osteoblasts on titanium and steel surfaces.

Commercially pure titanium (cpTi), titanium alloys, and steel are often used for dental and orthopedic implants. In these applications titanium is considered the "gold standard." However, tissue reactions around titanium implants and the changing trend to leave orthopedic devices in the body have led to a new examination of the preferred material. This in vitro study tested the behavior of osteoblasts on cpTi, Ti-6Al-7Nb, and stainless steel with surface designs similar to clinical implants. After surface characterization by scanning electron microscopy and profilometry, cell proliferation and the differentiation parameters of alkaline phosphatase (ALP) activity and osteocalcin were measured. For all materials tested, the growth curves showed a similar kinetic. On Ti-6Al-7Nb, ALP activity was significantly lower when compared with steel, and cpTi and did not change over the time. ALP activity increased moderately on steel and cpTi. Osteocalcin levels were higher on both titanium materials than on steel. Based on undisturbed cell growth and the relatively high alkaline phosphatase and osteocalcin levels, we suggest that cpTi provides the best biocompatibility with regard to proliferation, in addition to more reliable early and late differentiation markers of human osteoblasts in vitro.

Alkaline Phosphatase↗

PubMed2006

[The ti-epiplating system in bone anchored hearing AIDS].

The advent of bone-anchored hearing aids with titanium implants has markedly improved patient management. There are two systems on the market for performing the requisite osseointegration. The aim of our study was to evaluate the Ti-Epiplating system, since no data have been published on this in the literature thus far. Between November 2002 and March 2005, we anchored the BAHA snap coupling via the Ti-Epiplating system in 8 patients in a single session. The patients were followed-up at regular intervals to assess clinical and audiometric results and subjective satisfaction. The postoperative hearing threshold with the BAHA was in the former bone conduction range. In the Freiburg speech test, a significant improvement was found for monosyllables (free-field), and the hearing loss for numbers showed a mean reduction from 75 to 30 dB. There has been no implant loss in our collective thus far. Good to very good results were evaluated for the quality of life in the "International Inventory of evaluation of hearing aids" (IIEH). Clinics that use Medicon's osteosynthesis system can safely and reliably achieve inexpensive and audiometrically successful BAHA management by a comparatively simple surgical procedure.

Aged↗

PubMed2005

Growth factor-loaded scaffolds for bone engineering.

The objective of the study presented here was to investigate the bone inductive properties as well as release kinetics of rhTGF-beta1- and rhBMP-2-loaded Ti-fiber mesh and CaP cement scaffolds. Therefore, Ti-fiber mesh and porous CaP cement scaffolds were provided with these growth factors and inserted in subcutaneous and cranial implant locations in rats and rabbits. In vitro, a rapid release of rhTGF-beta1 was observed during the first 2 h of the Ti-fiber mesh scaffolds. During this time, more than 50% of the total dose of rhTGF-beta1 was released. Following this initial peak, a decline in the level of rhTGF-beta1 occurred. After 1 week, the entire theoretical initial dose was observed to have been released. This in contrast to the rhTGF-beta1 and rhBMP-2 release of the porous CaP cement scaffolds. Here, no substantial initial burst release was observed. The scaffolds showed an initial release of about 1% after 1 day, followed by an additional marginal release after 1 week. Histological analysis revealed excellent osteoconductive properties of non-loaded Ca-P material. Inside non-loaded Ti-mesh fiber scaffolds, also bone ingrowth occurred. Quantification of the bone ingrowth showed that bone formation was increased significantly in all scaffold materials by administration of rhTGF-beta1 and rhBMP-2. Consequently, we conclude that the release kinetics of growth factors from porous CaP cement differs from other scaffold materials, like metals and polymers. Nevertheless, orthotopic bone formation in a rabbit cranial defect model was stimulated in rhTGF-beta1- and rhBMP-2-loaded CaP cement and Ti-fiber mesh scaffolds compared with non-loaded implants.

Animals↗

PubMed2004

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA, Ti alloy and YSZ components.

Aerosols↗

PubMed2005

Improvement of surface bioactivity on titanium by water and hydrogen plasma immersion ion implantation.

We have investigated the surface bioactivity of titanium after water and hydrogen plasma immersion ion implantation. Plasma immersion ion implantation (PIII) excels in the surface treatment of components possessing a complicated shape such as medical implants. In addition, water and hydrogen PIII has been extensively studied as a method to fabricate silicon-on-insulator (SOI) substrates in the semiconductor industry and so it is relatively straightforward to transfer the technology to the biomedical field. In our investigation, water and hydrogen were plasma-implanted into titanium sequentially. Our objective is that water PIII introduces near-surface damages that trap hydrogen implanted in the subsequent step to improve the surface bioactivity while the desirable bulk properties of the materials are not compromised. Ti-OH functional groups can be detected on the (H(2)O+H(2))-implanted titanium surface by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. After incubation in simulated body fluids (SBF) for cytocompatibililty evaluation in vitro, bone-like hydroxyapatite was found to precipitate on the (H(2)O+H(2)) implanted samples while no apatite was found on titanium samples plasma implanted with water or hydrogen alone. Human osteoblast cells were cultured on the (H(2)O+H(2))-implanted titanium surface and they exhibited good adhesion and growth. Our results suggest a practical means to improve the surface bioactivity and cytocompatibility of medical implants made of titanium.

Biocompatible Materials↗

PubMed2001

Connective tissue orientation around dental implants in a canine model.

The objective of this study was to evaluate the orientation of collagen in the canine gingival connective tissue to a titanium surface (TI), and to hydroxyapatite coatings applied by plasma-spraying (HAPS) and ion beam assisted deposition (IBAD), on the supracrestal region of dental implants after 3 and 4 months. The effects of induced peri-implantitis on the soft connective tissue apposed to the implant were also evaluated. The use of these three surface types allowed for the evaluation of the effects of chemical composition (TI vs. IBAD; same topography) and topography (HAPS vs. IBAD; similar chemical composition) on the collagen fiber orientation. The majority of collagen fibers were found to be parallel to the implant surface, and there was no significant effect of surface type on orientation. There was a significant effect of inflammation on the connective tissue attachment length. The loss of bone height and concomitant gingival recession reduced the length of soft connective tissue apposed to the implant zone designed for collagen fiber attachment.

Analysis of Variance↗

PubMed1997

[Analysis of pure titanium implants-bone interface by TOF-SIMS].

In order to study the Titanium-bone interaction and integration mechanism, the titanium implant was implanted in the tibia of 9 Newzealand rabbits, and the Ti-bone interface performed for 1, 3, and 6 months were examined and analyzed by fluorescence microscope and advanced TOF-SIMS techniques. The results showed that Ti-bone tissue was integrated closely in a very reactive manner. Both physical and chemical integration occurred in the Ti-bone interface. The Ti-bone could diffuse into the bone tissue though the diffusion was very limited. It was up to 100 microns in depth during the early period. The diffusion density was high, and later in a smooth distribution. Furthermore, while Ti+ diffused into the bone tissue, other elements such as Ca+, OH-, O-, etc, could also diffuse into titanium in exchange. The growth pattern around the bone tissue was in two fashions, one was implantefugal and the other was implantopetal. In this study, based on the ionic distribution, osmosis and impurity elements distribution, the Ti-bone integration mechanism was discussed at molecular and atomic level.

Animals↗

PubMed2005

A 3-year retrospective study of Cresco frameworks: preload and complications.

PURPOSE: The aim of this retrospective clinical study was to evaluate the clinical outcome of fixed implant-supported complete prostheses on Astra or Brånemark implants when using either conventional cast frameworks or frameworks produced according to the Cresco Ti Precision method (Cresco Ti Systems Sàrl., Lausanne, Switzerland). MATERIALS AND METHODS: Forty-six patients treated 3 years previously were divided into four groups according to implant system and framework design. Clinical examinations were performed and case records were scrutinized. The stability for each prosthesis retention screw was recorded as the torque profile and was monitored using the Osseocare torque controller (Nobel Biocare AB, Göteborg, Sweden). Complications in association with implants and superstructures were registered. Patient opinions were recorded. The significance level was set to 5%. RESULTS: The Astra-Cresco group demonstrated a lower degree of prosthesis retention screw stability compared with the Astra group. No differences among the four groups were seen regarding plaque, bleeding on probing, or marginal bone resorption. The Brånemark group (Brånemark System, Nobel Biocare AB) demonstrated more mechanical complications than the Brånemark-Cresco group. Mobile prostheses were found in the Brånemark and the Astra-Cresco groups. Fracture of veneer was seen in 20% of the prostheses and was more frequently found in the groups with mobile prostheses. Sixty percent of the prostheses showed reactions in the surrounding soft tissues. The most common reaction was mucosal proliferation. No differences were detected in the patients' opinions. CONCLUSION: Within the limitations of this retrospective study, the following can be concluded: (1) compared with conventional frameworks, the Cresco distortion correction method does not provide a better clinical outcome after prosthesis connection in patients with fixed implant-supported complete prostheses; and (2) the two framework-producing methods behave differently on Astra implants compared with Brånemark implants concerning prosthesis retention screw stability, mechanical and biologic complications, and reactions in patients with fixed implant-supported complete prostheses.

Adult↗

PubMed1994

Remodelling of bone around hydroxyapatite and titanium in experimental osteoporosis.

The affinity of the tibia bone for cylinders of hydroxyapatite (HA) and Ti-6Al-4V was investigated in three experimental animal models: intact rat tibiae, ovariectomized rat tibiae and ovariectomized plus neurectomized rat tibiae. The affinity index (the length of bone directly apposed to the implant/the total length of the bone-implant interface x 100%) was calculated. In intact and ovariectomized tibiae, no significant difference existed between the affinity index of HA and Ti-6Al-4V. In ovariectomized plus neurectomized tibiae, the affinity index of HA was greater than for Ti-6Al-4V from 8 to 24 wk after implantation (8 wk, P < 0.05; 12 wk, P < 0.005; 24 wk, P < 0.05). The affinity index of Ti-6Al-4V in normal tibiae was greater than that in ovariectomized or ovariectomized plus neurectomized tibiae. There was no significant difference of the affinity index of HA between normal, ovariectomized or ovariectomized plus neurectomized tibiae. Osteoporotic bone demonstrated a greater affinity to HA than Ti-6Al-4V in an experimental animal model.

Animals↗

PubMed2003

IL-6 and PGE2 release by human osteoblasts on implant materials.

Regarding orthopaedic implant loosening it has been hypothesized that particle-activated macrophages release interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha). This in turn stimulates osteoblasts to release interleukin-6 (IL-6) and prostaglandin E(2) (PGE(2)). These mediators recruit and activate osteoclasts and may therefore lead to bone resorption and loss of implant fixation. In this study we compared the ability of different materials to induce the release of IL-6 and PGE(2) from primary isolated, human osteoblasts without preceding activation by macrophages. We tested stainless steel, cobalt-chromium alloy (CoCrMo), commercially pure titanium (cpTi), Ti-6Al-7Nb and Ti-6Al-4V processed in the same manner as corresponding clinical implants. After 12 and 24h the cells had actively secreted IL-6 and PGE(2). There were no clear differences among the implant materials or with the plastic control. The amount of factors the cells released in our study compare well with the findings of other authors who investigated osteoblasts on plastic. In comparison with the literature these amounts are lower than secretion levels of osteoblasts stimulated with implant particles, IL-1 or TNF-alpha. Moreover, other authors found that osteoclasts require higher concentrations of PGE(2) to become activated than the concentrations measured in our experiments. Therefore, the amount of PGE(2) released from the osteoblasts in our study is probably not sufficient to induce osteolytic activity. Because of contradictory statements in the literature it is unclear if the measured IL-6 concentrations promote osteolytic activity. Differences in material composition does not significantly influence the release of these factors if the materials have similar surface roughnesses.

Biocompatible Materials↗

PubMed2003

Comparison of tissue reaction and osteointegration of metal implants between hydroxyapatite/Ti alloy coat: an animal experimental study.

BACKGROUND: One important clinical application of hydroxyapatite (HA) is coating on metal implants to stimulate osteo-integration thus enhancing fixation of the implant to bone, especially plasma-sprayed HA coating applied on Ti alloy substrate. The poor bonding strength between HA and Ti alloy has been of great concern to orthopedists. The biocomptable coat such as Ti alloy (TiO2) coat is one method to improve adhesive strength. OBJECTIVE: The objective of this study was to detect and analyze possible differences in bone formation, bone integration and tissue reaction between group I (uncoated Titanium), group II (Hydroxyapatite coated Titanium), and group III (Hydroxyapatite/TiO2 coated Titanium) implant specimens when embedded into bony hosts. METHOD: Rectangular specimens were implanted into the femoral bone of adult dogs in randomly different sites including: proximal left, proximal right, distal left, distal right. The tailor-made implant specimens were inserted in 5 x 5 mm preprepared sockets. Radiographic evaluation was taken at 0, 1, 3 and 6 months. All animals were sacrificed at 3 and 6 months post implantation. The femoral bone containing implants were dissected and then prepared to be further investigated. The bone-implant interface was analyzed by H&E surface staining, radiography and scanning electron microscopy. Data concerning percentage of osteointegration and adhesiveness of hydroxyapatite layer from different kinds of implants along the entire length of each implants were collected and analyzed for evaluation of any significant differences. RESULTS: No osteo-integration was noted in Group I, but there was 25.57 per cent osteointegration in Group II and 28.63 per cent in Group III. No statistically significant differences were observed between Group II and Group III. However, the coating layer in Group II was found to have detached, in some area, from the metal substrate. Histologically, no adverse tissue reaction was found around any kind of implant. CONCLUSION: Biocompatable bond coat is one of the methods to improve adhesive strength of hydroxyapatite coated implants. In the present study it could be concluded that, besides the improvement in adhesiveness, the intervening TiO2 coating layer had no negative effect concerning bone formation and integration and also showed no adverse surrounding soft tissue reaction.

Animals↗

PubMed1995

Glass-ceramic-coated titanium hip endoprosthesis. Experimental study in rabbits.

Titanium alloy hip endoprostheses coated with a bioactive glass ceramic (BGC) were followed in rabbits. All test endoprostheses remained stable, and image analysis showed an average of 78% bonding of the BGC-coated implants to bone at 52 weeks. The uncoated Ti-alloy controls demonstrated an average of 37% bone coverage after 52 weeks. By scanning electron microscopy the thickness of the BGC reaction layer was found to stabilize at 60 microns after bioactive bone bonding. The results indicate that the BGC coating must be thicker than the reaction layer to prevent detachment from the core metal.

Alloys↗

PubMed2003

TAK-778 enhances osteoblast differentiation of human bone marrow cells cultured on titanium.

TAK-778 induces bone growth in in vitro and in vivo models. The aim of this study was to evaluate the osteogenic potential of TAK-778 on human bone marrow cells cultured on commercially pure titanium (cpTi). Cells were cultured either in absence or in presence of TAK-778 (10(-5)M) on cpTi in supplemented alpha-MEM. For attachment evaluation, cells were cultured for 4 and 24h. After 7, 14, and 21 days, cell proliferation, cell viability, total protein content, alkaline phosphatase (ALP) activity, and bone-like formation were evaluated. TAK-778 did not affect cell attachment and viability. Cell number was reduced by TAK-778. ALP activity, total protein content, and bone-like formation were increased by TAK-778. These results suggest that initial cell events such as cell attachment are not affected by TAK-778 while events that indicate osteoblast differentiation including reduced cell proliferation, and increased both ALP activity and bone-like formation are enhanced by TAK-778 in presence of cpTi. It means that TAK-778 could be a useful drug to improve the osseointegration of implants by both enhancing and accelerating bone formation on Ti surface.

Adolescent↗

PubMed1999

Analysis of push-out test data based on interfacial fracture energy.

Push-out testing is frequently used to assess the interfacial shear strength developed at a bone-biomaterial interface during in vivo experiments. The aim of the present research was to assess the in vivo performance of a novel substrate/coating combination and to introduce a more rigorous fracture mechanics analysis of the push-out test data. An adhesively bonded hydroxyapatite (HA), and a Ti-6Al-4V alloy plasma sprayed with HA, were implanted in female New Zealand white rabbits for up to 6 months in duration. After death, push-out tests were carried out and the shear strength was calculated in the conventional way, together with microscopical examination of crack paths. A finite element model was drawn up representing four potential failure mechanisms. The measured "failure shear strengths" in conventional analysis were approximately equal for the two coatings. However, JC at failure calculated from the model was 210 J m(-2) at the novel adhesively bonded HA/bone interface and 5 J m(-2) at a conventional titanium/plasma-sprayed HA interface. The conventional shear strength approach is strongly test dependent, and we believe that the fracture energy approach represents a more rigorous analysis of the real failure criterion in the implant/host tissue structure.

Journal Article↗

PubMed2000

Stress transmission through Ti-Ni alloy, titanium and stainless steel in impact compression test.

Impact stress transmission of Ti-Ni alloy was evaluated for biomedical stress shielding. Transformation temperatures of the alloy were investigated by means of DSC. An impact compression test was carried out with use of split-Hopkinson pressure-bar technique with cylindrical specimens of Ti-Ni alloy, titanium and stainless steel. As a result, the transmitted pulse through Ti-Ni alloy was considerably depressed as compared with those through titanium and stainless steel. The initial stress reduction was large through Ti-Ni alloy and titanium, but the stress reduction through Ti-Ni alloy was more continuous than titanium. The maximum value in the stress difference between incident and transmitted pulses through Ti-Ni alloy or titanium was higher than that through stainless steel, while the stress reduction in the maximum stress through Ti-Ni alloy was statistically larger than that through titanium or stainless steel. Ti-Ni alloy transmitted less impact stress than titanium or stainless steel, which suggested that the loading stress to adjacent tissues could be decreased with use of Ti-Ni alloy as a component material in an implant system.

Journal Article↗