PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Ti implants”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed2004

Surface treatments and roughness properties of Ti-based biomaterials.

Nowadays, the use of implanted devices is a well-acknowledged practice in the field of orthopaedic and dental surgery. Scientific research and clinical experience suggest that the successful exploitation of these devices mainly depends on osseointegration, considered as both anatomical congruency and load-bearing capacity. Indeed, the osseointegration process is influenced by a wide range of factors: anatomical location, implant size and design, surgical procedure, loading effects, biological fluids, age and sex, and, in particular, surface characteristics. For this reason, several attempts have been aimed at modifying implant surface composition and morphology to optimise implant-to-bone contact and improve integration. Preliminary interactions between implanted materials and biological environment are deemed to be governed by the surface properties; they control the amount and quality of cell adhesion on the surface and, consequently, cell/tissue growth. Thus, surface properties govern new bone tissue formation and implant osseointegration. This paper reviews the state of art in the field of physical, chemical and biochemical treatments commonly used on Ti-based biomaterials for the production of biomedical devices. In particular, roughness characteristics due to physical and chemical techniques are investigated; the development of biologically active surfaces by means of biochemical functionalisation is also considered.

Adsorption↗
PubMed2004

Development of a beta-type Ti-12Mo-5Ta alloy for biomedical applications: cytocompatibility and metallurgical aspects.

Ti-based biocompatible alloys are especially used for replacing failed hard tissue. Some of the most actively investigated materials for medical implants are the beta-Ti alloys, as they have a low elastic modulus (to inhibit bone resorption). They are alloyed with elements such as Nb, Ta, Zr, Mo, and Fe. We have prepared a new beta-Ti alloy that combines Ti with the non-toxic elements Ta and Mo using a vacuum arc-melting furnace and then annealed at 950 degrees C for one hour. The alloy was finally quenched in water at room temperature. The Ti-12Mo-5Ta alloy was characterised by X-ray diffraction, optical microscopy, SEM and EDS and found to have a body-centred-cubic structure (beta-type). It had a lower Young's modulus (about 74 GPa) than the classical alpha/beta Ti-6Al-4V alloy (120 GPa), while its Vickers hardness remained very high (about 303 HV). This makes it a good compromise for a use as a bone substitute. The cytocompatibility of samples of Ti-12Mo-5Ta and Ti-6Al-4V titanium alloys with various surface roughnesses was assessed in vitro using organotypic cultures of bone tissue and quantitative analyses of cell migration, proliferation and adhesion. Mechanically polished surfaces were prepared to produce unorientated residual polished grooves and cells grew to a particularly high density on the smoother Ti-12Mo-5Ta surface tested.

Animals↗
PubMed1985

Preliminary studies of the histopathological responses to Ti-13% Cu casting alloys.

A preliminary study of some of the biological properties of a new dental casting alloy (Ti-13% Cu) was undertaken by employing the skeletal muscle implantation test in rabbits. Routine histopathological and chemical analysis techniques were utilized to study in vivo tissue reactions of skeletal muscle to this alloy. A moderately thick, somewhat cellular fibrous connective tissue capsule surrounded the implants after 2 wk. Remodelling of the fibrous tissue into a thin acellular tissue capsule occurred at 52 wk after implantation. Chemical analyses failed to detect deposition of either Ti or Cu corrosion products at the implant sites or within major organs.

Animals↗
PubMed2006

Microrough titanium surface affects biologic response in MG63 osteoblast-like cells.

The purpose of this study was to define the surface properties of prepared titanium (Ti) disks, which served as a model system, and to contrast the biologic response of MG63 cells exposed to Ti disks with different levels of surface roughness. The surface properties interact with each other, resulting in a change of other surface qualities in addition to roughness due to the surface roughening procedure. The machined Ti disks were roughened by sandblasting and electric glow discharging. The surface properties of the Ti specimens were inspected through a comprehensive surface analysis. MG63 cell behaviors were compared along with cell number, alkaline phosphatase (ALP) activity, Runx2 gene expression, and type I collagen production. Statistics were evaluated, using analysis of variance (ANOVA). The sandblasted Ti disks demonstrated well-controlled surface roughness features and meaningful average roughness ranges, including the surface roughness of the "modern" microrough implant, used clinically. With increasing Ti surface roughness, the cell number decreased, while the ALP activity, type I collagen production, and Runx2 gene expression increased significantly. The rougher the Ti surface was, the sooner the Runx2 gene was expressed. Based on these results, we suggest that the microrough Ti surfaces of the 1-3 mum range may contribute effectively to osteogenic differentiation and proliferation in MG63 cells.

Animals↗
PubMed2000

Effect of unintentional exposure of 2-stage implants upon subsequent osseointegration: histologic findings 6 months postloading.

The purpose of this study was to evaluate the effect of early spontaneous exposure of 2-stage implants upon subsequent histologic bone contact following occlusal loading. As part of a study comparing 2 types of metallic threaded implants, 48 implants (24 CPTi and 24 Ti-13Nb-13Zr) were placed in maxillary and mandibular posterior sites in 6 baboons. Implant exposure was evaluated at time of placement and at each weekly visit for the first 3 weeks, then at 1, 2, and 3 months, and also at 6 months for the maxilla. Block sections were removed 6 months after the implant restoration was placed into function. One third (33%) of the maxillary implants became exposed, while 66.5% of the mandibular implants became exposed, mostly at 1 to 3 weeks. For all maxillary implants, fibrous tissue contact in the unintentionally exposed group (20.0%) was significantly greater than in the group that remained submerged (7.7%). Maxillary implants remaining submerged exhibited more sinus contact. For all mandibular implants, bone contact in the exposed group (38.9%) was significantly greater than in the submerged group (24.3%). Similarly, exposed implants exhibited less fibrous tissue contact. All other parameters in both maxillary and mandibular arches were statistically similar when comparing unintentionally exposed implants to those that remained submerged. This study suggests that accidental exposure of 2-stage implants should result in overall similarities in postloading bone contact to 2-stage implants that remain submerged during the early postoperative healing period.

Animals↗
PubMed2002

Long term tissue response to titanium coated with diamond like carbon.

Diamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. The samples were explanted after 1, 3, 6 and 12 months and the tissue-cell interaction was studied. Our data indicate both DLC/Ti and bare Ti to be compatible with skeletal muscle.

Animals↗
PubMed1995

Hydroxyapatite-clay bone fixation for loaded implants.

A clay containing hydroxyapatite (HA clay), which was made by mixing HA granules (range of sizes: 0.1-0.3 mm) and a saline solution of sodium alginate, was inserted into the medullary canal of an osteotomized rabbit's tibia with a Ti-6Al-4V titanium alloy implant. Each implant had a conical portion for bearing load. The shear strength of the bone-implant interface for the implant with HA clay was significantly greater than that for the implant without HA clay 3 months postoperatively (P < .02), while there was no significant difference between the two strengths 1 week postoperatively. Under microscopic observation, the percentage of area of newly developed bone was also significantly greater for the implant with HA clay than for the implant without HA clay 3 months postoperatively (P < .04). This study suggests that HA clay encouraged adequate bone fixation of the loaded implant in 3 months, while the clay was not effective for immediate fixation.

Alloys↗
PubMed1997

High testosterone prior to song crystallization inhibits singing behavior in captive yearling dark-eyed juncos (Junco hyemalis).

In passerine birds, song is considered crucial in advertising reproductive and territorial status to conspecifics. Variation in the quality and frequency of song may be influenced by hormonal effects during the individual's development. This variation in turn may affect the function and potency of song. We studied the influence of testosterone on vocal production in first-year male dark-eyed juncos (Junco hyemalis), using subcutaneous silastic implants filled with testosterone. Subjects were visually but not acoustically isolated from one another and after capture had no exposure to female or adult male models. Implants were administered when subjects were in the plastic song phase (i.e., after they had begun to sing but before song was fully crystallized). Control males (C males) received empty implants. Experimental males were of two classes: TI males received one dose of testosterone (a single 10-mm implant), and TII males received two doses. Testosterone implants kept plasma levels high well into the breeding season, whereas in nature, levels normally drop after territorial acquisition and pair formation. Control males sang at higher rates than testosterone-treated males of both classes and had the greatest number of song types. This inhibitory effect of testosterone on vocal production suggests that disturbance of seasonal profiles of testosterone in birds may interfere with the production of species-typical song.

Animals↗
PubMed1989

Ultrastructural differences of the interface zone between bone and Ti 6Al 4V or commercially pure titanium.

Commercially pure (CP) titanium and Ti 6Al 4V alloy were sputtered onto polycarbonate plastic implants to analyse hard tissue reactions to the two metals. The implants were inserted in the tibial metaphyses of five rabbits. Three months later they were removed and processed for light microscopy (LM) and transmission electron microscopy (TEM) investigations. At the LM level, disordered woven bone was seen in the interface zone of Ti 6Al 4V, whereas organized bone was observed in direct contact with the CP titanium implants. TEM examination of Ti 6Al 4V sections revealed a 500-1000 A thick collagen-free proteoglycan layer compared to 200-400 A for CP titanium. A surface analysis test was performed to compare the magnetron sputtered film with bulk Ti 6Al 4V alloy. This test revealed no major differences between the experimental implant and the bulk alloy. More natural-like tissue reactions were observed to CP titanium than to Ti 6Al 4V alloy.

Alloys↗
PubMed2005

In vivo cytokine secretion and NF-kappaB activation around titanium and copper implants.

The early biological response at titanium (Ti), copper (Cu)-coated Ti and sham sites was evaluated in an in vivo rat model. Material surface chemical and topographical properties were characterized using Auger electron spectroscopy, energy dispersive X-ray spectroscopy and interferometry, respectively. The number of leukocytes, cell types and cell viability (release of lactate dehydrogenase) were determined in the implant-interface exudate. The contents of activated nuclear transcription factor NF-kappaB, interleukin-6 (IL-6) and interleukin-10 (IL-10) were determined by enzyme linked immunosorbent assay. An increase in the number of leukocytes, in particular, polymorphonuclear leukocytes, was observed between 12 and 48 h around Cu. A marked decrease of exudate cell viability was found around Cu after 48 h. The total amounts of activated NF-kappaB after 12 h was highest in Ti exudates whereas after 48 h the highest amount of NF-kappaB was detected around Cu. The levels of cytokine IL-6 were consistently high around Cu at both time periods. No differences in IL-10 contents were detected, irrespective of material/sham and time. The results show that materials with different toxicity grades (titanium with low and copper with high toxicity) exhibit early differences in the activation of NF-kappaB, extracellular expression and secretion of mediators, causing major differences in inflammatory cell accumulation and death in vivo.

Animals↗
PubMed1990

Cementless total joint arthroplasty prostheses with titanium-alloy articular surfaces. A human retrieval analysis.

Surgical implants of titanium alloy (Ti-6Al-4V) have been found to be susceptible to abrasive wear, resulting in the well-known phenomenon of metallosis. In the presence of the acrylic debris generated by loose joint arthroplasty prostheses, this abrasive wear is greatly increased. However, the bone loss seen in these cases has generally been presumed to be due to the osteolytic effects of particulate acrylic, not the alloy debris, which has generally been assumed to be biocompatible. To examine the in vivo effects of titanium-alloy wear without the added presence of acrylic debris, a comprehensive analysis was made of cementless human joint arthroplasty prostheses with Ti-6Al-4V alloy surfaces articulating on ultra-high molecular weight polyethylene (UHMWPE). Specimens, including the prostheses, synovium, pseudocapsule and additional soft tissues, and periarticular bone, were retrieved from 22 hips and two knees. Specimens were examined by histologic techniques, energy-dispersive X-ray analysis, and electron microscopy. Serial sections of the implants were evaluated for tissue ingrowth. Tissues surrounding all joints implanted more than one year showed some degree of discoloration indicative of metallosis, whereas after two years the synovium was hypertrophic and villiform. Histologic evaluation showed good fixation by bony ingrowth in the vast majority of cases, although location and extent of ingrowth was dependent on numerous factors. Viability of ingrowth bone was established by fluorochrome labeling. However, despite good biologic fixation, cavitary osteolysis of the bone surrounding the implants was frequently identified. These lesions were filled with sheets of aggressive macrophages within a matrix of fibrous tissue and necrotic debris. Under polarized light the macrophages were found to be filled with alloy and polyethylene fragments of a characteristic size. Osteoblast-mediated remodeling of bone was infrequently observed. Instead, the bone was resorbed along a front in contact with the granulomatous tissues filling the cystic lesions. Visible burnishing was observed on every articular surface, with a linear relationship between wear and time implanted. By one year the surfaces were covered with a characteristic "scratch and gouge" pattern, similar on all sizes of femoral heads as well as the total knee prostheses. This study demonstrates that the combination of Ti-6Al-4V alloy and UHMWPE, when used as a bearing surface combination in total joint arthroplasty prostheses, results in excessive wear of both metal and polymer.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1997

A totally implantable drug delivery system for local therapy of the middle and inner ear.

Local therapy of middle and inner ear diseases is being used, but is restricted to cases of ear drum perforation or to repeated invasive intratympanic drug application by the physician. In accordance with the Medical Device Directive (class III), a bone-anchored, totally implantable drug delivery system (TI-DDS) has been developed. It includes a micropump for subcutaneous, patient-controlled activation, a drug reservoir and a septum port. A thin guide-wired catheter leads from the pump outlet to the point of application in the mastoid or middle ear cavities. Local inner ear therapy with suitable drugs is possible by positioning the catheter's end near the round window membrane. The system requires no battery and will offer a wide range of patient-controlled bolus applications (25 microliters per activation). We first analyzed the three-dimensional implantation geometry of the mastoid cavity. Basic micromechanical problems have been solved in order to create several prototypes. The TI-DDS has already undergone extensive in vitro testing. Recent results of pump rate precision and digital pressure force testing are promising. Local drug treatment for conditions such as lidocaine-sensitive tinnitus, secretory otitis media, Meniere's disease, localized pain and intralesional cancer is under discussion. Furthermore, local application of future biotechnological trophic factors for inner ear treatment is anticipated. The basic engineering is completed and initial animal tests are in preparation.

Animals↗
PubMed2003

Histological and mechanical investigation of the bone-bonding ability of anodically oxidized titanium in rabbits.

The purpose of this study was to histologically and mechanically investigate the in vivo bone-bonding ability of anodically oxidized titanium (AO Ti) with an anatase crystal layer on its surface. AO Ti plates, anodically oxidized at 155 V in 1 M H2SO4, were implanted into the proximal metaphyses of mature rabbit tibiae for 4, 8, 16, and 24 weeks and investigated by light microscopy, scanning electron microscopy and detaching test. High bone-bonding ability, comparable to our previous study data of the bioactive titanium produced by sodium-free alkali and heat treatment, was observed at the early stages of implantation. However, no substantial increase was demonstrated. AO Ti plates bonded to bone directly, with no intervening soft tissue layer, and no breakage of the AO Ti layer was observed. The AO Ti layer was porous through to the titanium substrate, while the porosity was low. Apatite-like deposition into the pores of the AO layer was observed only in the superficial zone. The lack of improvement of bone-bonding ability in the later stages of implantation may be attributed to the low porosity and to the superficial ingrowths of apatite-like deposits into the pores of the AO Ti layer.

Animals↗
PubMed2000

Evaluation by electrochemical tests of the passive film stability of equiatomic Ni-Ti alloy also in presence of stress-induced martensite.

In this study, potentiodynamic polarization scans, potentiostatic scratch tests, and modified American Society for Testing and Materials F746 tests were carried out in simulated body fluids on commercial orthodontic wires made of different classes of materials and on titanium used as a reference. The stability of passivating film, evaluated by electrochemical techniques that abruptly damage it, e.g., potentiostatic scratch test, increased in the following order: Ni-Ti </= stainless steel < Co-Cr alloy < Ti. Because satisfactory biocompatibilty of implants relies on the presence of a stable and efficient self-repairing passive film, this ranking should be considered in view of in vivo applications. Moreover, scratch tests show that it is not possible to enhance the performance of Ni-Ti samples by modifying surface-passive film by dipping in an HF/HNO(3) mixture. Finally, straining of Ni-Ti wires under superelastic conditions and consequent presence of stress-induced martensite does not substantially modify their localized corrosion resistance.

Corrosion↗
PubMedDate not supplied

Application of capacitively coupled electric field enhances periimplant osteogenesis in the dog mandible.

PURPOSE: Expeditious postoperative ingrowth of bone into dental implants is desired for clinically successful fixation of oral implants. The present study was performed to evaluate the effect of applying a capacitively coupled electric field (CCEF) on periimplant osteogenesis in the dog mandible. MATERIALS AND METHODS: Twelve adult male beagles were used in this study. All of the premolars on both sides of the mandible were removed from each dog. A POI (Ti-6Al-4V) 3-piece implant (3.7 mm in diameter and 8.0 mm in length) whose surface had been treated with anodic oxidation was placed into each test site by self-tapping. Daily application of CCEF (8 h/day) was initiated on the day following the surgery and was continued through the day of sacrifice. A CCEF was induced by an external source delivering 10-Vp-p, 60-kHz sine-wave signals through an oral electrode plate. One side of the mandible of each dog was treated with CCEF, while the other side was not. On the control side, an oral electrode plate was attached for 8 hours per day, but CCEF was not applied. The effect of daily application of CCEF on the ingrowth of bone into the implant was examined at 14, 21, or 30 days after implant placement. A fourth control group was not treated with CCEF and was maintained for 90 days to confirm that CCEF treatment enhances bone ingrowth in dental implants. RESULTS: Daily application of CCEF significantly increased the bone-contact ratio at days 14, 21, and 30 after implant placement in comparison with the respective controls. The bone-area ratios of the 14- and 21-day CCEF-treated groups were significantly larger than those of the respective controls and were similar to those of the 90-day control group. CONCLUSION: CCEF treatment increases periimplant osteogenesis in the dog mandible, confirming its usefulness in oral implantology.

Alloys↗
PubMed2005

Biomechanical and allergological characteristics of a biodegradable poly(D,L-lactic acid) coating for orthopaedic implants.

A poly(D,L-lactic acid) surface coating (PDLLA) has been developed to optimize interactions at the implant-tissue interface. Mechanical and allergological characteristics were evaluated in the present study to elucidate possible indications and limitations prior to clinical application. Implants of stainless steel and Ti-6Al-4V and Co-Cr-Mo alloys were coated with PDLLA, and mechanical stability was studied during intramedullary implantation into rat and human cadaver bones and during dilation of coronary artery stents. Elongation resistance was examined on AlMgSi alloy specimens. Furthermore, proliferation of peripheral blood mononuclear cells of nickel-allergic donors and controls and interleukin-4 and interferon-gamma levels were measured in the presence of coated/uncoated implants and after stimulation with phytohemagglutinin or NiSO4. PDLLA remained stable on the implants with a minimum of 96% of the original coating mass and tolerated lengthening of at least 8%. Further lengthening was followed by microcracking and cohesive failure within the coating. PDLLA exerted no suppressive effect upon spontaneous and pan-T-cell mitogen inducible T-cell proliferation. Furthermore, specific proliferation to nickel in cells of nickel-allergic blood donors and production of interleukin-4 and IFN-gamma were not influenced by the coating. PDLLA coating proved high mechanical stability on different orthopaedic implants and did not influence in vitro T-cell reactivity towards specific biomaterials.

Adult↗
PubMed1997

Preoperative assessment of the implantable middle ear pump system using CT scans and conventional X-rays of the temporal bone.

A completely implantable micropump system for drug delivery has recently been developed. After implantation in the temporal bone, this microdosage system enables application of drugs into the middle ear and round window area. Successful application of this new technology depends upon a suitable fit of the micropump within the patient's temporal bone. To obtain information about the fit before surgery, we analyzed 50 cadaver temporal bone specimens before total mastoidectomy, using conventional X-ray and spiral CT scans for water volume determination. Spiral CT is a feasible method for preoperative planning of the surgical implantation of the implantable middle ear micropump system (TI-DDS). The best parameter for a preoperative judgment is the volume of the mastoid cavity, as determined by CT. Implantation may be recommended when the mastoid volume, as measured by CT, is greater than 6.6 ml. To be certain that the implantable drug delivery system will be implantable, a cut-off value of 9.3 ml seems to be advisable. Spiral CT imaging is of great value as a tool for testing implantation preoperatively. The imaging is accomplished in approximately 30 seconds. Our preliminary results with cadaveric temporal bones are encouraging. Further studies are needed in order to transfer the results to a clinical implantation situation.

Ear, Middle↗