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At least 1,153 records · Page 64Linked to original sources
PubMed1990

[Bond strength of dental luting cements to titanium castings].

This study compared the tensile bond strength of dental luting cements to the titanium castings with gold alloy (Type IV), 12% Au-Ag-Pd alloy and Ni-Cr alloy in dental clinical practice. In this experimental condition, the zinc phosphate cement did not adhere to any dental casting alloy tested. The tensile bond strength of polycarboxylate cement to the titanium castings was 96 kg/cm2, about two times as high as that gold alloy (Type IV). The tensile bond strength of the glass ionomer cement to titanium castings was 32 kg/cm2, about two times as high as that of dental precious alloys. The tensile bond strength of the adhesive resin cement to titanium castings was 220 kg/cm2, about three times as high as that of dental precious alloys.

Dental Alloys↗
PubMed1990

[Determination of titanium flow by the tracer element molten method in the dental precision casting. 1. The principle of flow visualization and application to simple castings].

The tracer element molten (TEM) method has been developed for flow visualization of molten Titanium in dental precision casting. The principle of this technique is as follows. When Titanium is cast, the tracer element wire inserted previously into the selective point of the sprue is molten little by little and distributed according to the molten Titanium flow in the mold cavity. After solidification, to observe the flow pattern, the tracer element needs to be analyzed on a section of the casting by EPMA equipped with the stage scan mapping system. This technique using Ag, Au, Pd or Pt as a tracer has been applied to some simple castings in shape and has been confirmed to be a very powerful technique for Titanium flow visualization in dental castings.

Dental Casting Technique↗
PubMed1990

Tissue reaction involving an intraoral skin graft and CP titanium abutments: a clinical report.

Focal areas of gingival hyperplasia surrounding the transmucosal portions of titanium implants have been attributed to poor hygiene, lack of attached gingival tissues, and titanium allergy. Following mandibular vestibuloplasty and placement of a split-thickness skin graft, two of five patients developed persistent proliferation of the epithelial tissue surrounding endosseous CP titanium dental implants. In both circumstances, traditional gingivectomy procedures, chemotherapeutic agents, and aggressive oral hygiene measures failed to adequately control the hyperplastic response. Following replacement of the titanium abutments with custom-fabricated gold abutments, the epithelial condition appeared to return to normal.

Adult↗
PubMed1989

A study of in vitro attachment of Streptococcus sanguis and Actinomyces viscosus to saliva-treated titanium.

This study examined the initial attachment of Streptococcus sanguis G9-B and Actinomyces viscosus T14V to saliva-treated powdered enamel and titanium surfaces. Using an in vitro adherence model, significantly lower numbers of Actinomyces viscosus T14V bound to the saliva-treated titanium surface when compared to that of the similarly treated enamel. The binding of Streptococcus sanguis G9-B to titanium or enamel did not vary significantly. A comparison of the percentage of cells bound to the titanium surface revealed that S sanguis cells attached in significantly higher numbers when compared to the A viscosus cells.

Actinomyces↗
PubMed1989

[Polarographic determination of titanium in natural water].

Titanium has a very sensitive catalytic polarographic wave in the system of cupferon-hexamine-sodium sulfate at pH 6.0-6.4. The catalytic current was proportional to the content of titanium. High blank of the reagents could be improved by extraction with the system of cupferron-chloroform. For determination, samples were filtered with quantitative filter paper, but it was not necessary for drinking water samples. The filtration was acidified with HCl to 0.5% (V/V) and heated in a boiling water bath for 30 min, 5 ml sample was sufficed to most analyses. The detection limit was 0.12 microgram/L. The coefficient of variation was 8% for 6 determinations at 0.2 microgram/L. Three levels of titanium were spiked to one sample, and it was found that the recoveries were 96-101%. The proposed method was applied to rain water, well-head water, well water, tap water and river water. The content of titanium of most samples was less than 2 micrograms/L.

Polarography↗
PubMedDate not supplied

[Effect of titanium on the osteogenic and proliferative potentials of bone marrow cells in vitro].

The impact of titanium (BT-1.0) on proliferative and osteogenic potential of in vitro bone marrow was studied in rabbits. Titanium showed no influence on proliferation and differentiation of osteogenic determined cells precursors in the bone marrow. These cells' growth showed a titanium-tropicity. The authors came to a conclusion that the use of titanium in combination with automyeloplasty can be successfully used to accelerate the bone integration in implanted dental patients.

Animals↗
PubMed1989

Aseptic loosening in total hip arthroplasty secondary to osteolysis induced by wear debris from titanium-alloy modular femoral heads.

Since 1984, we have used components made of titanium alloy for total joint arthroplasty. Recently, two patients needed revision hip arthroplasty, approximately three years after the initial procedure, because of aseptic loosening secondary to severe osteolysis that had been induced by metallic debris. Although implants made of titanium alloy have many favorable qualities--most importantly, superb biocompatibility--the alloy is more susceptible to wear by particles of acrylic cement and tends to generate more polyethylene wear than do components made of stainless steel or chromium-cobalt. A new process of implanting ions has reportedly improved resistance to wear as well as fatigue properties and has enhanced the resistance to corrosion of the implants. Although, to our knowledge, only in vitro studies of this process have been reported to date, we recommend avoiding the use of components made of titanium alloy in which ions have not been implanted. We suggest considering the possibility of osteolysis secondary to appreciable metallic debris in patients who have aseptic loosening of titanium-alloy components that were not implanted with ions.

Adult↗
PubMed1988

Metallic wear in failed titanium-alloy total hip replacements. A histological and quantitative analysis.

We conducted extensive histological examination of the tissues that were adjacent to the prosthesis in nine hips that had a failed total arthroplasty. The prostheses were composed of titanium alloy (Ti-6Al-4V) and ultra-high molecular weight polyethylene. The average time that the prosthesis had been in place in the tissue was 33.5 months (range, eleven to fifty-seven months). Seven arthroplasties were revised because of aseptic loosening and two, for infection. In eight hips cement had been used and in one (that had a porous-coated implant for fifty-two months) no cement had been utilized. Intense histiocytic and plasma-cell reaction was noted in the pseudocapsular tissue. There was copious metallic staining of the lining cells. Polyethylene debris and particles of cement with concomitant giant-cell reaction were present in five hips. Atomic absorption spectrophotometry revealed values for titanium of fifty-sic to 3700 micrograms per gram of dry tissue (average, 1047 micrograms per gram; normal, zero microgram per gram), for aluminum of 2.1 to 396 micrograms per gram (average, 115 micrograms per gram; normal, zero micrograms per gram), and for vanadium of 2.9 to 220 micrograms per gram (average, sixty-seven micrograms per gram; normal, 1.2 micrograms per gram). The highest values were found in the hip in which surgical revision was performed at fifty-seven months. The concentrations of the three elements in the soft tissues were similar to those in the metal of the prostheses. The factors to which failure was attributed were: vertical orientation of the acetabular component (five hips), poor cementing technique on the femoral side (three hips), infection (two hips), and separation of a sintered pad made of pure titanium (one hip). A femoral component that is made of titanium alloy can undergo severe wear of the surface and on the stem, where it is loose, with liberation of potentially toxic local concentrations of metal debris into the surrounding tissues. It may contribute to infection and loosening.

Adolescent↗
PubMed1986

Comparison of porous titanium-surfaced and standard smooth-surfaced bone plates and screws in an unstable fracture model in dogs.

Bilateral midshaft femoral osteotomies were fixed with a 3-mm fracture gap in 6 dogs. In each dog, one femur was fixed with a porous titanium-surfaced bone plate and screws, whereas the opposite femur was fixed with a standard smooth-surfaced bone plate and screws. The mean removal torque for porous titanium-surfaced screws (32.3 kg X cm) was significantly (P less than 0.01) greater than the mean removal torque for standard screws (4.4 kg X cm). Osseous tissue ingrowth into the surface of porous titanium-surfaced screws was verified by histologic examination of the bone-screw interface. Radiographic and histologic examinations of the osteotomy gaps showed accelerated primary gap healing in osteotomies fixed with porous titanium-coated implants, compared with slower callus healing seen in osteotomies fixed with standard smooth-surfaced implants.

Animals↗
PubMed1995

[Bone reaction to contact with a granulated titanium surface. Apropos of 101 total hip prostheses with six years follow-up].

PURPOSE OF THE STUDY: The failures of cemented hip prosthesis have prompted research into a new process of fixation and a new design of the system. Stability is achieved by adherence the bone onto a blasted titanium surface. The shell is implanted without screws. The stem has an anatomical shape to improve metaphyseal fixation of the femur. MATERIAL AND METHODS: The rugosity of the blasted titanium surface which has an average depth of 50 millimicrons allows new bone-growth without any fibrous interposition. Bone ingrowth starts from the third week onward and within two years a homogenous bone sheath is produced. Several experiments on animals have shown the quality of the bone-growth onto this blasted surface. The bone reaction has the same qualities as a hydroxy-apatite coating. It is of better quality than other titanium surfaces. The press-fit obtained by the shape allows this bone-growth. The reliability of this biological fixation is enabled for the shell by the perfect distribution of loads due to the hemispherical shape and the greatest possible thickness of the polyethylene. For the stem, the purely metaphyseal fixation appears to be a very important factor to enable painless long term stability. Another advantage of this method of fixation is that the prosthesis can be removed without any damage to the bone and can be reimplanted without any artificial fixtures with excellent results. RESULTS: Histological results. Within a few weeks a new strip of bone will settle onto the porous metal without any fibrous interposition. This strip is connected to the cortical bone by small brackets of bone which gradually thicken over the months and guarantee anchorage. Radiological results. In 1 per cent of all cases a border or a gap has formed around the shell; there is no migration. Around the proximal part of the stem thin ribs in tension appeared at the beginning and over the months the width of these increased. Within two years they had filled the space between the metal and the cortical bone. Around the distal part of the stem, which is smooth, there is no bone-growth. Clinical results. In nearly 94 per cent of cases a perfect result was obtained which could only be achieved if the prosthesis was perfectly stable. There was mild pain in only 4 per cent of cases. Revision and observation. Two revisions for ceramic head fracture confirmed that it was possible to remove the prosthesis without damage to the bone. DISCUSSION: A correct pressure distribution on bone would appear desirable for the two components. For the acetabulum a thick layer of polyethylene and for the stem a metaphyseal anchorage are desirable. CONCLUSION: It is perhaps too early at this stage to speculate on the long term results. Nevertheless as of now we observe that the principle of a metaphyseal fixation significantly decreases the incidence of mild pain. On the other hand, the follow-up of nearly seven years of bone fixation on a blasted titanium surface would seem sufficient to show us that this method has proven to be a significant improvement.

Animals↗
PubMed1995

The use of MRI-compatible titanium segmental spinal instrumentation in pediatric patients with intraspinal tumor.

Severe kyphosis is a frequent complication of multiple laminectomies for the treatment of intraspinal tumors in growing children. Early Segmental Spinal Instrumentation (SSI) and posterior spinal fusion can prevent this complication, but because of ferromagnetic properties of conventional stainless steel implants, magnetic resonance imaging (MRI) performed to determine completeness of the resection and later for recurrence of the tumor becomes difficult. To overcome the problems with postoperative imaging, we have resorted to early stabilization of the spine following laminectomy with titanium alloy implants. The decreased ferromagnetic properties of titanium alloy result in less scatter distortion of the image, thus permitting a better follow-up of the tumor. This paper reports five consecutive patients with stabilization of the spine with titanium alloy implants and posterior spinal fusion done at the time of laminectomy. The use of titanium alloy implants in these patients allowed detailed MRI follow-up in all cases, and in two patients offered the surgical team information that altered or affected the patient's care.

Adolescent↗
PubMedDate not supplied

Morphologic and radioautographic studies of bone formation in relation to titanium implants using the rat tibia as a model.

A rat tibia model was developed to analyze bone formation leading to osseointegration with threaded titanium implants. Miniaturized titanium implants were placed in the anterior aspect of the upper tibia of rats weighing 350 g. Twenty-four rats were involved; 12 rats were sacrificed at 6 weeks, and another two rats were sacrificed weekly for 6 weeks following implantation. Four days prior to sacrifice, the animals were injected intraperitoneally with 3H-proline (10 microCi/g body weight). The rats were fixed by perfusion with 5% glutaraldehyde, and the tibia were decalcified and embedded in Epon. The implants were removed from the embedded bone by fracturing, and the specimens re-embedded. Sections were prepared for light and electron microscopy and radioautography. Morphologic observations indicated that implant placement resulted in bone necrosis and resorption. This was followed by bone growth from the old bone surfaces filling the threads with vascular channels and new lamellar bone. Osseointegration was complete at 6 weeks in all animals examined. Electron microscopy at various places along the bone-titanium interface showed an amorphous layer, a granular electron-dense layer, or a layer of uncalcified collagen fibrils. At each week after surgery, radioautography showed the position and thickness of new bone labeled with 3H-proline during the last 4 days. Radiolabeled new bone was deposited only on previously existing bone and extended toward the available space. Since there was no apparent relationship between the implant and the new bone, it was suggested that titanium is biocompatible, but not necessarily osteoinductive.

Animals↗
PubMed1994

The new titanium Greenfield vena cava filter: initial experience and review.

The Greenfield vena cava filter is an established therapeutic option in the prevention of pulmonary embolism. The development of a 12 French modified titanium Greenfield filter (TGF) has made it possible to insert the filter percutaneously and to have a low complication rate. We report our initial experience with percutaneous insertion of the 12-French titanium Greenfield vena cava filter for 6 patients who all had major extensive deep venous thrombosis (DVT) and contraindications to anticoagulation. The inferior vena cava (IVC) filters were inserted in all the 6 patients via the internal jugular route without difficulty. There was no bruising, haematoma or bleeding complications despite the use of the 12 French system. The IVC filter was opened without cross-snaring of the filter legs in all 6 patients. This was confirmed with cranio-caudal, left anterior oblique and right anterior oblique views of the deployed filter. There was however some asymmetry of the filter leg positions but it did not cause any significant angulation of the filter in relation to the IVC. The IVC filters were firmly secured with no filter migration immediately post-procedure. The 12-French titanium Greenfield vena cava filter was safely deployed percutaneously with no complications in our small series of patients. With the use of titanium in the design of Greenfield filter, the clinical effectiveness and performance is maintained while providing for easier insertion and reduction of patient discomfort.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Evaluation of the soft tissue interface at titanium implants with different surface treatments: experimental study on rabbits.

Recently, a dominant influence of the surface roughness parameters for the soft tissue reaction at the implant tissue interface was found in an experimental study on sheep. The purpose of the present study is to correlate the surface roughness parameters of different experimental bone plates to the results of the histomorphometric analyses of the adjacent soft tissues. Pure titanium plates (35 x 5 x 1 mm) with six different surface treatments and electropolished stainless steel plates were tested. Prior to implantation the surface roughness parameters were determined using a profilometer and a scanning electron microscope. The tibia of adult rabbits served as test sites. At least four plates of each type were implanted. Three months postoperatively the implants were harvested with an intact tissue envelope and were left in situ for the histological preparation. The difference in the roughness parameters is statistically significant for most surface conditions and has an effect on the soft tissue reaction. The histological evaluation shows a significant higher number of blood vessels for steel plates in comparison to titanium plates with handground and blasted surface conditions. For the rough type of anodized titanium surfaces a significantly thinner soft tissue capsule is found, compared to electropolished steel plates. For the steel plates a fluid film was found between the implant and the adjacent tissue layer. The material and the surface roughness of the implant, determine the tissue reaction at the interface. The rough type of anodized titanium implants seems to be preferable.

Animals↗
PubMed1993

Metal release from titanium fixtures during placement in the mandible: an experimental study.

Titanium screw taps and titanium fixtures were investigated by SEM before and after experimental use. Peri-implant bone surfaces were examined immediately after surgery and 5 months after implantation by SEM using the SE mode, backscattered electron imaging, and EDX analysis to detect titanium contamination of the bone specimens. The Ti content of the livers, kidneys, and lungs of six Göttingen minipigs, which had received two screw implants each, was determined using flameless atomic absorption spectroscopy and compared to a control group with no implants. Results showed that Ti particles were abraded and deposited on the bone surface during the preparation of implant beds. Five months after placement, particles were no longer observed on the bone surface next to the implants. Determination of the Ti concentration of the inner organs showed that the lungs contained the highest amount of titanium. The Ti content of the kidneys and livers was much lower. All values differed significantly from those of the control group (P < .01).

Alveolar Process↗
PubMed1993

Osteoinductive activity of composites of bone morphogenetic protein and pure titanium.

Titanium sponges were infused with bone morphogenetic protein (BMP-Ti), and the osteoinductivity of the resultant composite was measured. New bone formation occurred three weeks after implantation and was identified by soft x-ray analysis. Quantitative analysis showed no significant difference between BMP-Ti composites and control samples (BMP only). Consequently, pure titanium neither inhibited nor promoted BMP activity. Chondrocytes and new bone formation occurred in direct contact with the surfaces of the titanium. X-ray microanalysis demonstrated new bone formation inside the pores of the titanium sponges. The BMP-Ti composite has interesting properties as an osteoinductive implant and has potential practical clinical applications.

Animals↗
PubMedDate not supplied

Effects of titanium dioxide passive film crystal structure, thickness, and crystallinity on C3 adsorption.

The effects of titanium dioxide passive film crystal structure, thickness, and crystallinity on C3 adsorption from diluted human plasma were measured. Titanium dioxide surfaces created include (1) 70-nm anatase and rutile films comprising a mixture of amorphous and microcrystalline titanium dioxide, (2) 140-nm anatase and rutile films with greater crystallinity than the 70-nm films, (3) 70-nm aged anatase films with approximately the same crystallinity as that of the 140-nm anatase films, (4) sintered anatase and sintered rutile with no underlying metal, representing completely crystalline oxide films of infinite thickness, and (5) electropolished titanium. All combinations of experimental variables of surface type, exposure time, and plasma dilution were replicated four times. Anatase and rutile C3 surface concentrations increased with increased oxide thickness and crystallinity. The 70-nm aged anatase film isotherm more closely matched that of the 140-nm than of the 70-nm film, indicating that some property associated with oxide crystallinity is more influential in C3 adsorption than properties associated with oxide thickness alone. Concentrations of C3 were equal for equivalent anatase and rutile surfaces, except at high plasma concentrations and long exposure times, in which more C3 was adsorbed to anatase, suggesting that crystal structure may not be a significant controlling factor.

Adsorption↗
PubMed1996

Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits.

In the present study, the influence of initial instability on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that they were either stable (control), rotation-mobile, or totally mobile. Implants were also inserted in the distal femoral condyles, representing an implantation bed with mainly cancellous bone, so they either showed no initial mobility (control) or were rotation-mobile. After 12 weeks of healing, the implants were retrieved, together with surrounding bone, fixed, dehydrated, and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone to titanium contact, and the amount of bone occupying the threads, were calculated, whereafter the outcome of the different locations were compared. All retrieved implants were clinically stable at the of the experiment. For the tibia sites, a statistically significant less bone to titanium contact, and a less amount of bone in the threads, were found for the totally mobile implants, as compared to the corresponding initially stable controls. Moreover, a statistically significant higher amount of bone was found in the threads of the rotation-mobile implants inserted in the femoral condyle as compared to their initially stable controls. The study indicated that initial rotation-mobility, independent if it occurs in cortical or trabecular bone, does not necessarily lead to an inferior integration of unloaded implants. However, initial total implant mobility within the cortical layer results in a statistically significant less amount of bone around the implants, as compared to stable controls.

Animals↗