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PubMed1992

Reduced corrosion of CP Ti and Ti-6A1-4V alloy endosseous dental implants after glow-discharge treatment: a preliminary report.

Inductively coupled argon plasma spectroscopic analysis was used to quantify titanium, aluminum, and vanadium corrosion products released by superficial layers of identically shaped commercially pure titanium and Ti-6A1-4V alloy dental implants. Halves of each of two originally sterile groups were analyzed directly from the manufacturer's packaging and the other halves received glow-discharge treatment prior to their corrosion assay. The implants were incubated in pH 3 modified saline solution and were analyzed after 2- and 12-week corrosion periods. Implants treated with glow discharge showed statistically significant reduction in the amounts of corrosion products released, apparently as a result of glow-discharge-produced surface oxides of greater passivity than originally present.

Aluminum↗

PubMed2004

Accumulation of aluminium in lamellar bone after implantation of titanium plates, Ti-6Al-4V screws, hydroxyapatite granules.

Titanium plates, Ti6Al4V screws and surrounding tissues, and biopsies of hydroxyapatite (Osprovit) grafts of maxillary sinus lifting were investigated to evaluate the release and accumulation of ions. Optical microscopy, SEM and X-ray microanalysis were carried out to evaluate the plates and screws removed from patients presenting inflammation and biopsies. Ions release from metallic appliances or leaching from granules towards soft tissues was observed. An accumulation of aluminium but not titanium was found in soft tissues. A peculiar accumulation of aluminium in the dense lamella of newly formed bone was recorded. The results seem to indicate that biological perturbations may be related to aluminium release from the tested biomaterials. The aluminium content of these biomaterials, its diffusion and accumulation are discussed. Further studies on ion release from biomaterials and aluminium fate in skeletal tissues are suggested.

Adult↗

PubMed1999

Three-dimensional bone structure around hydroxyapatite and titanium implants in rabbits.

Long-term support of dental implants requires adequate bone thickness in the area surrounding the implant. A three-dimensional examination, including calculations of percent bone-implant contact and percent bone volume, was conducted to clarify the bone structure around pure titanium (Ti) and dense hydroxyapatite (HA) implants. The implants were installed in the tibiae of rabbits, and the bone structure was examined after 2, 4, 6 and 8 weeks. The bone formation following implantation differed in the cortical bone and cancellous bone areas. In the cortical bone area, the percent bone-implant contact and percent bone volume were comparatively consistent for both Ti and HA implants during the observation period. In the cancellous bone area, both findings were influenced by the implantation period, and the chronological bone structure in the cancellous bone area also differed between Ti and HA implants. The percent bone-implant contact and percent bone volume in the Ti implant increased over 8 weeks, whereas the dense HA implant increased for the first 4 weeks and then decreased. The implant materials, Ti and HA, affected the bone remodeling in the cancellous bone area.

Analysis of Variance↗

PubMed2005

On the feasibility of phosphate glass and hydroxyapatite engineered coating on titanium.

In this report, bioactive calcium phosphate (CaP) coatings were produced on titanium (Ti) by using phosphate-based glass (P-glass) and hydroxyapatite (HA), and their feasibility for hard tissue applications was addressed in vitro. P-glass and HA composite slurries were coated on Ti under mild heat treatment conditions to form a porous thick layer, and then the micropores were filled in with an HA sol-gel precursor to produce a dense layer. The resultant coating product was composed of HA and calcium phosphate glass ceramics, such as tricalcium phosphate (TCP) and calcium pyrophosphate (CPP). The coating layer had a thickness of approximately 30-40 microm and adhered to the Ti substrate tightly. The adhesion strength of the coating layer on Ti was as high as 30-33 MPa. The human osteoblastic cells cultured on the coatings produced by the combined method attached and proliferated favorably. Moreover, the cells on the coatings expressed significantly higher alkaline phosphatase activity than those on pure Ti, suggesting the stimulation of the osteoblastic activity on the coatings. On the basis of these observations, the engineered CaP coating layer is considered to be potentially applicable as a hard tissue-coating system on Ti-based implants.

Durapatite↗

PubMed2003

Surface composition analysis of failed cementless CoCr- and Ti-base-alloy total hip implants.

The surfaces of retrieved failed cementless total hip implants made of cobalt-chromium-molybdenum casting alloy and of wrought titanium 6-aluminum 4-vanadium alloy were studied with the use of scanning-electron microscopy (SEM), energy-dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). New implants of the same make served as controls. The XPS scans revealed a dense carbon layer on the entire analyzed specimen. The relative composition of the titanium alloy implants showed an overall agreement with the international standards for implants for surgery, and the overall surface composition did not change over the period of the implantation. However, an inhomogeneous distribution of the constituents could be demonstrated in the retrieved as well as in the new MEC-screw rings made of TiAl6V4 alloy, an implant that has been linked to a high early failure rate. In the CoCr-alloy components (Lord-screw rings) a high percentage of aluminum, mainly organized in aluminum inclusions, was found in the retrieved as well as in the new implants.

Adult↗

PubMed1997

XPS characterization of surface films formed on surface-modified implant materials after cell culture.

Nitrogen ion-implanted Ti-6Al-4V, Ti-5Al-2.5Fe and 316 L stainless steel and nitrogen or carbon sputter-coated samples were inoculated with rat bone marrow. The interface between the cell layer and the substrata was studied by X-ray photo-electron spectrometry and observed by scanning electron microscopy (SEM). Ca and P were detected on all materials after in vitro cell culture. Titanium appears to be present mainly in the form of TiO2.

Journal Article↗

PubMed1994

Abrasive wear of ceramic, metal, and UHMWPE bearing surfaces from third-body bone, PMMA bone cement, and titanium debris.

The debris generated by the progressive wear of total joint replacement (TJR) devices is considered a primary cause of osteolysis, bone resorption, and premature failure of artificial hips and knees. The vast majority of this debris originates from the UHMWPE articulating surfaces caused by tribological interaction with the opposing metal or ceramic surface and hard particulates contained in the sinovial fluid. Entrapment of third body debris, such as cortical bone, PMMA cement, and titanium debris, between the articulating surfaces can cause abrasion of both the hard bearing surface and the UHMWPE. The propensity for abrasive wear is dependent on the relationship between the hardness of the third-body debris and the hardness of the bearing surfaces. To gain a better understanding of this relationship and its effect on wear, the abrasive wear behavior of several metal and ceramic bearing surfaces was characterized in terms of the hardness of both the third-body debris and the metal or ceramic substrate. The effects of abrasion and increased surface roughness of the metal or ceramic surfaces on wear of the UHMWPE was also determined. In addition, the amount of UHMWPE wear was quantified in terms of the amount (particles/ml) of titanium fretting-type debris contained in solution. The results of this investigation showed the resistance to abrasive wear of the metal and ceramic bearing surfaces to increase with increasing surface hardness. Bone debris, PMMA cement, and titanium debris produced visible abrasion of all metal surfaces including nitrogen ion implanted Ti-6Al-4V. The ceramic bearing surfaces showed no evidence of abrasion and produced the least amount of UHMWPE wear. The wear of UHMWPE sliding against Co-Cr-Mo was found to increase with increasing levels of 1.48 microns titanium debris added to the wear test solution. The rate of UHMWPE wear increased rapidly for concentrations of titanium debris in the test solution exceeding about 10(5) particles/ml. These test results suggest that third-body particles, both large and small, are capable of causing increased abrasive wear of UHMWPE, and that abrasion of the hard bearing surfaces will occur if the hardness of the third-body debris exceeds the hardness of the metal or ceramic bearing surface.

Biocompatible Materials↗

PubMed2002

Dynamics of bone marrow pressure with tapping of titanium and hydroxyapatite implants in rabbits.

The purpose of the present study was to evaluate the difference in stress transfer between titanium (Ti) and hydroxyapatite (HA) by the measurement of bone marrow pressure using a catheter pressure transducer. Ti and HA implants were inserted in the tibiae of rabbits. A hole of 1 mm in diameter was drilled in the bone and a fine catheter pressure transducer was placed in the bone marrow through a tube. The top of the abutment was vertically tapped with an impulse hammer, and the acceleration signal from the hammer and pressure signal from the catheter pressure transducer were examined. The time of contact (impulse duration) recorded in the impulse with Ti and HA was 166+/-17 micro sec and 164 +/- 17 micro sec, respectively. Maximum bone marrow pressure (BMP) with Ti and HA was 54.2 +/- 32.6 and 47.5 +/- 10.0 mmHg, respectively. Variation of the BMP with Ti was significantly larger than that with HA (P < 0.05). A negative correlation coefficient between impulse duration and BMP was found. The results of the present study suggest that the stress transfer is different between Ti and HA implants using dynamics of the bone marrow pressure.

Acceleration↗

PubMed2003

Mechanical performance of the new posterior spinal implant: effect of materials, connecting plate, and pedicle screw design.

STUDY DESIGN: A newly designed spinal implant was tested to evaluate multicycle stiffness and fatigue resistance. OBJECTIVES: To investigate the effect of different materials, connecting plate, and pedicle screw design on the mechanical performance of the spinal implant. SUMMARY OF THE BACKGROUND DATA: The addition of cross-linkages did not significantly increase implant compression/flexion stiffness, but accelerated fatigue failure at the rod junctions. Both Ti-6Al-4V spinal implants and the 316L stainless-steel counterparts have been used extensively for clinical cases; however, design factors establishing the proposed superiority of the Ti-6Al-4V implant for fatigue resistance have not, as yet, been extensively studied. METHODS: Twenty implants with connecting plates (two materials by two screw designs by five implants) and five implants without connecting plates were assembled to UHMWPE blocks and cyclically loaded from 60 N to 600 N at a frequency of 5 Hz. RESULTS: Failure sites for the tested prototypes were at the cephalic screw hubs or rod-plate junctions. All Ti-6Al-4V implants demonstrated reduced stiffness compared to the structurally identical 316L analogs. The use of connecting plates raised the stiffness of the 316L prototypes without cross-links. However, elimination of the connecting plate avoided stress concentration at the rod/plate junctions and increased fatigue life. The Ti-6Al-4V new system with the minimal notch effect at the screw hubs achieved greater fatigue resistance than its 316L counterpart. By contrast, enlargement of the inner-hub diameter resulted in greater gains for fatigue resistance than for stiffness, especially for Ti-6Al-4V variants. CONCLUSIONS: Although Ti-6Al-4V was superior to 316L for endurance-limit properties, structural design of the Ti-6Al-4V implant dramatically affects fatigue resistance. This may explain the differences between existing studies and the current report, comparing fatigue life for implants made from these two materials. Our results reveal that Ti-6Al-4V must be carefully treated because of sensitivity to notch, with special consideration given to screw-hub design.

Alloys↗

PubMed1996

Histomorphological reaction of bone to different concentrations of phagocytosable particles of high-density polyethylene and Ti-6Al-4V alloy in vivo.

Wear debris has been implicated in the pathogenesis of loosening and osteolysis of total joint replacements by stimulating a foreign body and chronic inflammatory reaction capable of bone resorption. Whether increasing concentrations of wear particles have an adverse biological effect on bone has not been elucidated. We performed a histomorphological and semi-quantitative morphometric analysis of the reaction of bone to different concentrations of phagocytosable particles of high-density polyethylene (HDPE) and titanium 6-aluminium 4-vanadium alloy (Ti-6Al-4V) implanted in the rabbit tibia. The Ti-6Al-4V particles had a diameter of 4.0 +/- 4.4 microns (mean +/- SD); the HDPE particles averaged 4.7 +/- 2.1 microns. Suspensions of 10(6)-10(9) particles per ml were mixed in saline, sterilized, and introduced through a drill hole into the proximal tibia of 30 mature female rabbits. Controls included drilled, but non-implantable limbs. The animals were killed at 16 weeks and histological sections were made of the implant area. Histomorphological assessment was carried out using an interactive image analysis system. The parameters assessed included the presence of histiocytes, foreign body giant cells and inflammatory cells, the location and number of particles, the presence of haematopoeitic elements, fat or necrosis of the marrow, whether healing of the cortical window had taken place, and whether there was evidence of formation or resorption of bone by the periosteum, cortex and marrow. A semi-quantitative rating system was employed. Phagocytosable particles of Ti-6Al-4V and HDPE, in concentrations of 10(6)-10(9) particles per ml, evoked a histiocytic reaction without extensive fibrosis, necrosis or granuloma formation. This reaction occurred without disturbing the normal repair processes of bone formation and resorption to the surgical insult. A clear dose-response effect on the histological parameters assessed in this study was not noted. Using the present model, by 16 weeks, a similar "one time' particle load could be accommodated. The ongoing generation of particulate debris over a more extended period of time might be necessary before the remodelling processes of bone would be disturbed.

Alloys↗

PubMed2002

Initial tissue response to a titanium implant coated with apatite at room temperature using a blast coating method.

We previously reported a blast coating method (BC method) as a new coating method of titanium (Ti) with apatite (AP) at room temperature. The BC method gives much stronger AP coating on the Ti surface compared with those obtained by other room temperature coating methods. However, no in vivo study has been made, so far, to evaluate the stability or the tissue response to the implant. As an initial step to evaluate the feasibility of the BC method, we evaluated the tissue response and stability of AP coated Ti implant prepared with the BC method (AP-BC implant) using rats as experimental animals. The AP coating adhered tightly to the Ti surface even after the implant procedure and throughout the experimental period up to six weeks post operation. AP-BC implant caused no inflammatory response, showed strong bone response and much better osteoconductivity compared with the pure Ti implant. The new bone formed on the surface of AP-BC implants was thinner compared with that formed on the surface of Ti implant. Therefore, the AP-BC implant has a good potential as an osteoconductive implant material.

Animals↗

PubMed2004

Comparison of metal concentrations in rat tibia tissues with various metallic implants.

To compare metal concentrations in tibia tissues with various metallic implants, SUS316L stainless steel, Co-Cr-Mo casting alloy, and Ti-6Al-4V and V-free Ti-15Zr-4Nb-4Ta alloys were implanted into the rat tibia for up to 48 weeks. After the implant was removed from the tibia by decalcification, the tibia tissues near the implant were lyophilized. Then the concentrations of metals in the tibia tissues by microwave acid digestion were determined by inductively coupled plasma-mass spectrometry. Fe concentrations were determined by graphite-furnace atomic absorption spectrometry. The Fe concentration in the tibia tissues with the SUS316L implant was relatively high, and it rapidly increased up to 12 weeks and then decreased thereafter. On the other hand, the Co concentration in the tibia tissues with the Co-Cr-Mo implant was lower, and it increased up to 24 weeks and slightly decreased at 48 weeks. The Ni concentration in the tibia tissues with the SUS316L implant increased up to 6 weeks and then gradually decreased thereafter. The Cr concentration tended to be higher than the Co concentration. This Cr concentration linearly increased up to 12 weeks and then decreased toward 48 weeks in the tibia tissues with the SUS316L or Co-Cr-Mo implant. Minute quantities of Ti, Al and V in the tibia tissues with the Ti-6Al-4V implant were found. The Ti concentration in the tibia tissues with the Ti-15Zr-4Nb-4Ta implant was lower than that in the tibia tissues with the Ti-6Al-4V implant. The Zr, Nb and Ta concentrations were also very low. The Ti-15Zr-4Nb-4Ta alloy with its low metal release in vivo is considered advantageous for long-term implants.

Animals↗

PubMed2005

Zirconia to Ti-6Al-4V braze joint for implantable biomedical device.

A strong, hermetic, reliable, and biocompatible ceramic-to-metal seal is essential for many implantable medical devices. Yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) and a titanium alloy Ti-6Al-4V were selected as the ceramic and metal components of the seal because both materials have excellent mechanical properties and favorable biocompatibility. A brazing method using titanium nickel (TiNi)-clad braze filler material is presented to bond the components together forming a seal. Laboratory tests show that the ceramic-to-metal seal is hermetic, strong, and resistant to electrochemical corrosion. Twenty-eight microstimulators utilizing the ceramic-to-metal seals were implanted in seven sheep to stimulate the hypoglossal nerve. When the tissue was evaluated by gross inspection at necropsy and examined histologically by a pathologist, there were no signs of local hemorrhage, infection, or hypoglossal nerve tissue damage.

Alloys↗

PubMed1995

Effects of sublethal metal ion concentrations on osteogenic cells derived from bone marrow stromal cells.

Ions released from implant surfaces are suspected of playing some role in osteolysis surrounding metal prostheses. To understand how ions may affect osteogenesis, previous work exposed osteogenic cells to metal ions to study acute cytotoxic responses. The purpose of this study was to assess the long-term effects of sublethal ion concentrations on osteogenic cell proliferation and function. Bone marrow stromal cells were harvested from juvenile rats and exposed to solutions of ions associated with Co-Cr-Mo and Ti-6Al-4V implants. Cells were cultured for up to 4 weeks and assayed for total protein, alkaline phosphatase, osteocalcin, and calcium. Other than V+5, none of the ions affected cell proliferation, indicating that the chosen concentrations were sublethal as desired. V+5 elicited delayed gross toxicity not previously observed during acute experiments. At the chosen concentrations, Co+2, Cr+6, Mo+6, and Co-Cr-Mo alloy elicited little effect on cell proliferation and moderate effects on matrix mineralization. Cultures exposed to Ti+4, Al+3, and Ti-6Al-4V alloy also showed no decrease in cell number, but did show near total suppression of osteocalcin secretion and matrix mineralization. These results suggest that ions released from Ti alloy implants may interfere with osteoblastic cell differentiation, contributing to periprosthetic osteolysis by impairing normal osteogenesis.

Alkaline Phosphatase↗

PubMed1993

A new bioactive glass--ceramic as a coating material on titanium alloy.

Apatite--wollastonite-containing glass--ceramic (A--W . GC) has a strong ability to bond to bone and relatively high mechanical strength. Therefore, as a bulk material it has recently been applied clinically even in load-bearing sites. In this study, we modified A--W . GC by altering its composition ratio with the removal of CaF 2 and the addition of B 2O 3, and examined the potential use of the resulting new glass--ceramic as a material for coating on a titanium (Ti) alloy. The bioactivity of this new coating (NC) material and its bonding ability to bone were investigated mechanically and histologically. After implantation of the Ti alloy plate coated with this material into the tibiae of rabbits for 2, 3, 4, 8, and 25 weeks, a detaching test was performed. The detaching failure load of the NC plates was compared with those of A--W . GC plates, hydroxyapatite (HA) plates, and uncoated Ti alloy plates implanted in the same way. The failure load of NC was as high as that of A--W . GC for all periods, whereas it was significantly higher at 3 and 4 weeks than that of HA. Uncoated Ti alloy showed lower failure loads for all periods, differing significantly from the other materials. There was no breakage or detachment of the coating layer observed after the detaching test. Histological examinations by CMR, Giemsa surface staining, and SEM-EPMA showed that NC bonded directly to bone without any intervening soft tissue layer. A calcium--phosphorus-rich layer (apatite layer) was observed within the coating layer, as is the case in A--W . GC. These results indicate that this new glass--ceramic has earlier bone-bonding ability and high mechanical strength, making it a promising coating material.

Animals↗

PubMed1989

Classical external indwelling central venous catheter versus totally implanted venous access systems for chemotherapy administration: a randomized trial in 100 patients with solid tumors.

A prospective randomized trial was organized at the Institut Gustave-Roussy to assess the reliability of classical external catheters (CE) versus totally implanted access systems (TI) for delivering intravenous chemotherapy for a duration of at least 6 months. The analysis was performed on the 96 patients whose implantation succeeded (CE 46, TI 50). Failure was defined as loss of ability to function (followed by removal) within the 6-month period of the survey. Patients dying with functional catheters were considered as censored (15 cases) at the time of death. Twenty-four access systems were removed. The removal-free curves differ significantly (P less than 0.001), favoring the TI access systems. The main reasons for removal were: catheter fall (CE6, (TI 0), migration (CE 1, TI 1), infection (CE 5, TI 1), thrombotic occlusion (CE 1, TI 0) and venous complications (CE 1 thrombosis plus 1 pulmonary embolism, TI 1 thrombosis). In addition, a survey by questionnaire demonstrated a significantly better patient activity rate (P = 0.02) and hygiene (P less than 0.001) in the TI group. This prospective randomized study demonstrates that totally implanted access systems are more reliable, safer and better tolerated than classical external catheters for solid tumor patients undergoing intravenous chemotherapy for longer than 6 months.

Antineoplastic Agents↗

PubMed2003

Implant-retained mandibular overdentures with immediate loading: a 3- to 8-year prospective study on 328 implants.

PURPOSE: The purpose of this study is to evaluate prospectively survival and success rates of implants placed in the interforaminal area of edentulous mandibles and immediately loaded with an implant-supported overdenture. MATERIALS AND METHODS: Eighty-two patients, 33 males and 49 females, aged between 42 and 87 years (mean age 58.6 yr), presenting edentulous mandibles were rehabilitated with an implant-supported overdenture in the mandible. Three hundred twenty-eight screw-type osseointegrated implants (164 Ha-Ti, Mathys Dental, Bettlach, Switzerland; 84 ITI Dental Implant System, Straumann Institute, Waldenburg, Switzerland; 40 Brånemark Conical, Nobel Biocare AB, Gothenburg, Sweden; 40 Frialoc, Friatec, AG Mannheiti, Germany), were placed in the intraforaminal area of the mental symphysis (4 implants per patient). Immediately after implant placement, a U-shaped gold or titanium bar was fabricated and implants were rigidly connected with the bar and immediately loaded with an implant-retained overdenture. Success rate of implants was evaluated clinically and radiographically every year after the loading of the prostheses according to the following parameters: (1) absence of clinical mobility of implants tested individually after bar removal, (2) absence of periimplant radiolucency evaluated on panoramic radiographs, (3) absence of pain and radiologic or clinical signs of neural lesion, and (4) periimplant bone resorption mesial and distal to each implant less than 0.2 mm after the first year of prosthetic load. RESULTS: Of 328 implants placed, 296 were followed up from a minimum of 36 months to a maximum of 96 months, with a mean follow-up of 62 months. Seven implants in 6 different patients were removed owing to loss of osseointegration, whereas 18 implants, although still osseointegrated, did not fulfill success criteria due to bone resorption > 0.2 mm/year after the first year of loading. Despite implant losses, all patients maintained their bars supporting overdentures, although in 6 patients they were supported by 3 instead of 4 implants. The only patient who lost 2 implants received 2 new implants, which survived normally. Therefore, the absolute success and survival rates were 91.6% and 97.6%, respectively, whereas the cumulative survival and success rates of implants obtained with a life table analysis were 96.1% and 88.2%, respectively. CONCLUSIONS: Results of this study seem to demonstrate that survival and success rates of immediately loaded implants placed in the intraforaminal area of the mandible and rigidly connected with a bar through an implant-supported overdenture are consistent with those reported in the international literature as far as delayed loading is concerned after 3 years of loading. After longer observation times, this study demonstrated that, while survival rates of implants and bar-supported overdentures are still consistent with results published in the international literature pertaining to delayed loading, a moderate decrease in success rates of implants was found. Nevertheless, it must be stressed that this decrease (88.8 and 90.4% after a 7- to 8-year observation period for Ha-Ti and ITI implants) is related only to two implant systems; no data are available for the other two implant systems because of the shorter follow-up period.

Adult↗

PubMed1996

Transforming growth factor-beta stimulates bone ongrowth. Hydroxyapatite-coated implants studied in dogs.

Unloaded cylindrical grit-blasted titanium (Ti-6A-4V) implants (6 x 10 mm) coated with hydroxyapatite ceramic were inserted into the proximal part of the humerus of 20 skeletally mature Labrador dogs. The implants were initially surrounded by a 2 mm gap. In 10 dogs, HA-coated implants without growth factor were inserted in one humerus and implants with 0.3 microgram rhTGF-beta 1 adsorbed onto the HA coating were inserted in the contralateral humerus. In another group of 10 dogs, a dose of 3.0 micrograms rhTGF-beta 1 was tested in a similar design. All dogs were killed at 6 weeks after treatment. Results were evaluated by histomorphometry and mechanical push-out testing. Bone ongrowth was increased by one third, using the 0.3 mg rhTGF-beta 1 stimulation. Bone volume in the gap and mechanical testing showed no statistically significant differences between control and rhTGF-beta 1 stimulated implants. RhTGF-beta 1 only moderately enhanced bone ongrowth to hydroxyapatite-coated implants.

Alloys↗