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At least 1,621 records · Page 90Linked to original sources
PubMed1998

[An in vitro study on toxic effect of vanadium-titanium-magnetite dust on alveolar macrophage in rabbits].

OBJECTIVE: To study the toxic effect of vanadium-titanium-magnetite (VTM) dust on alveolar macrophage (AM) and its hazardous extent. METHODS: Survival rates, morphology and function of AM were compared in rabbits exposed to dust of VTM, vanadium oxide, titanium dioxide and silica in various doses and length of time with in vitro cell culture and putamen membrane cover glass transmission electron microscopy, and changes in activities of lactic dehydrogenase (LDH) and acid phosphatase (ACP) in cell culture were measured. RESULTS: Exposure to all the four kinds of dust could lead to decrease in survival rate of AM, increase in activities of LDH and ACP in the cell culture, and changes in their morphology and function to the extent dependent on the nature of dust. CONCLUSION: Toxic effect of exposure to VTM dust was lower than that to vanadium oxide and silica, but higher than that to titanium dioxide, which had slight toxic effect.

Acid Phosphatase↗
PubMedDate not supplied

Osseointegration of rough acid-etched titanium implants: 5-year follow-up of 100 minimatic implants.

During 1992, 100 Minimatic screw implants made of titanium alloy (titanium-aluminum-vanadium) with a machined rough acid-etched surface were placed in 63 consecutive partially edentulous patients. At second-stage surgery, which was performed after a 4- to 6-month healing period, none of the implants showed signs of mobility, peri-implant infection, or bone loss from the crest of the ridge. Each patient was restored with a fixed prosthesis and reexamined every 3 months during the first year. Periapical radiographs were taken annually up to 5 years. These revealed no signs of peri-implant radiolucencies involving any of the implants, and mean alveolar bone loss was less than 1 mm at the 5-year examination. One implant was considered a late failure because of a peri-implant infection that developed during the first year, although the implant was still functional at year 5. Another patient with 2 implants dropped out during the fifth year of the study, although both implants had been considered successful up to that point. Based on annual measurements of Plaque Index, Sulcular Bleeding index, pocket probing depth, attachment level, width of keratinized mucosa, and hand-tested mobility, 97 of the remaining 98 implants were considered successful, resulting in a 98% success rate. This 5-year study confirms that Minimatic machined acid-etched implants provide predictable osseointegration results and supports the conclusion of other reports that titanium implants with a rough surface can fulfill the requirements of Albrektsson et al (1986) for implant success.

Alloys↗
PubMedDate not supplied

Rate of pull-out strength gain of dual-etched titanium implants: a comparative study in rabbits.

The purpose of this study was to investigate the rate of pull-out strength gain of an etched titanium implant surface. Rabbit tibiae were used to compare machined titanium and proprietary dual-etched titanium implants. Two custom cylindric implants (3 mm in diameter and 4 mm in length) were placed in each right anteromedial tibia in 31 rabbits. At weeks 1, 2, 3, 4, 5, and 8, the implants in 5 rabbits were subjected to failure shear loading in a pull-out test. For shear failure testing, each tibial segment was mounted in a precision alignment jig, and an Instron pull-out test was performed on each implant. Beginning at week 3, there was a statistically significant difference (P < .01) between the dual-etched and the machined implants. There was a significant increase in strength for dual-etched implants between week 5 and week 8, while the machined implants did not show an increase during this time interval. The etched implants maintained a significantly greater pull-out strength for the remainder of the study, with a 3.2-fold greater mean strength at 8 weeks, equivalent to 6 months in humans. At 3 weeks, the etched implant's strength exceeded the strength that the machined implant had achieved at 8 weeks. In short-term healing in the rabbit tibia, the dual-etched surface demonstrated a more rapid rate of pull-out strength gain than the machined surface and remained significantly stronger throughout the 8 weeks of the study.

Acid Etching, Dental↗
PubMed2000

[A new self-retaining titanium-gold stapes prosthesis].

Various aspects of stapes surgery have been improved since its introduction in 1958 by Shea. However, fixation of the prosthesis on the long process of the incus remains difficult. Furthermore, the functional result of crimping cannot be predicted. Necrosis of the lenticular process still occurs. A new stapes prosthesis has been developed with the Kurz Co. The use of titanium allowed an innovative design: titanium has a shape memory, and a clip was constructed which uses this memory for fixation on the incus. Two new instruments were also developed to facilitate application of the prosthesis: a prosthesis inserter and a prosthesis crimper. The clip does not strangulate the incus; it is attached only to the superior and inferior surface of the incus, which are the crucial locations for mechanical transmission of the piston-like movements of the ossicular chain. Avoidance of circumferential attachment should reduce the risk of incus necrosis. Once the clip is pushed onto the incus no further crimping is necessary. The piston is of pure gold, as in this company's gold piston which has been in use for many years. In future the prosthesis may be all-titanium.

Gold↗
PubMedDate not supplied

Bone response to titanium alloy implants placed in diabetic rats.

Although dental implants continue to provide consistent and predictable treatment options for most patients, some people with uncontrolled systemic disease may be denied implant treatment. Diabetes is one such disease. According to the U.S. Centers for Disease Control and Prevention, diabetes is a leading cause of blindness, kidney failure, and amputations of the lower extremities. These complications result from microvascular disturbances associated with diabetes. The effect of diabetes on the healing of titanium implants has not been well established. In this study of 32 rats, diabetes was induced in 16 animals by injection of streptozotocin (65 mg/kg); the remaining 16 animals served as controls. Titanium alloy implants were placed in the tibiae of all 32 rats using standard surgical techniques. Implants healed for 14 days. Blood samples were obtained for serum glucose, osteocalcin, and alkaline phosphatase analyses. Implants were retrieved and processed for histomorphometric analyses. Three quantities were measured using light microscopy, video capture, and computer analysis: percent osseointegration (i.e., linear bone interface), associated bone volume percent, and contact frequency. Diabetic animals demonstrated significantly less osseointegration than controls. However, bone volume percent in diabetic animals was about 4 times greater than controls. Biochemical analyses were mixed; diabetic animals demonstrated increased serum osteocalcin levels compared to controls but decreased alkaline phosphatase. Based on the results of this study, it was concluded that the bone response associated with titanium alloy implants in the tibiae of diabetic rats is uniquely different from controls.

Alkaline Phosphatase↗
PubMedDate not supplied

Surface characterization of titanium-based implant materials.

This study examined the effects of different treatments (polished, electropolished, and grit-blasted) on the surface morphology and chemistry of commercially pure titanium and titanium-6% aluminum-4% vanadium. The structure and composition of the surfaces were evaluated using scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Auger microprobe analysis, and x-ray photoelectron spectroscopy. Surface roughness values at large scales were nearly identical for grit-blasted and electropolished samples, while at smaller scales, electropolished and polished samples had nearly identical quantitative roughness values. The surface oxide compositions were found to be primarily titanium dioxide on both materials for all surface treatments. No vanadium was seen with either x-ray photoelectron spectroscopy or Auger microprobe analysis for the alloy, indicating a possible surface depletion. Calcium was present on the grit-blasted samples, and calcium and chlorine were detected on the electropolished samples.

Alloys↗
PubMedDate not supplied

Removal torque and histomorphometric investigation of 4 different titanium surfaces: an experimental study in the rabbit tibia.

This study presents a histomorphometric and biomechanical comparison of bone response to commercially pure titanium screws with 4 different types of surface topographies placed in the tibial metaphysis of 12 rabbits. Each rabbit had 4 implants placed, 2 in each tibia. The 4 surface topographies were a machined surface, a grit-blasted surface, a plasma-sprayed surface, and an acid-etched (Osseotite) surface. After a healing period of 5 weeks, histomorphometric and removal torque data revealed a significantly higher percentage of bone-to-implant contact and removal torque for acid-etched implants compared to machined, blasted, and plasma-sprayed implants. Within the limits of this short-term experimental study, the results indicated that micro-rough titanium surfaces obtained with acid-etching procedures achieved a 33% greater bone-to-implant contact over machined titanium surfaces with an abutment-type roughness and provided enhanced mechanical interlocking.

Animals↗
PubMed2000

[Adsorption of human serum proteins to titanium dioxide].

In order to find an in vitro biochemical model for investigation of osseointegration in terms of dental implantology, the aim of the present study was to analyse the adsorption of human serum proteins to titanium dioxide. Titanium dioxide powder was suspended in human serum. After incubation and centrifugation the TiO2 with the adsorbed proteins were washed with distilled water, ethylendiaminetetraacetic acid (EDTA) supplemented with ammonium hydrogencarbonate (NH4HCO3) solution, and sodium dodecylsulphate (SDS), after centrifugation the supernatant fluid was collected and SDS polyacrylamide gel and native (Biomidi) gel electrophoresis were conducted to determine the type of the adsorbed proteins. Our results show, that albumin was adsorbed to TiO2, but it could be easily removed. The adsorption of a 94 kDa protein was much stronger than the other proteins. The method seems to be useful in the investigation of the protein adsorbing ability of differently treated titanium implant surfaces.

Adsorption↗
PubMed2000

Effects of titanium surfaces blasted with TiO2 particles on the initial attachment of cells derived from human mandibular bone. A scanning electron microscopic and histomorphometric analysis.

This study was performed to determine the effect of commercially pure titanium surfaces blasted with TiO2 particles on the biological responses of cells derived from human mandibular bone. The morphology and attachment of those cells were investigated on turned titanium surfaces (control) and surfaces blasted with 45 microns (standard), 45-63 microns, and 63-90 microns TiO2 particles. The surfaces were analyzed in a scanning electron microscope. Based on surface analyses reported elsewhere, the turned samples had the smoothest surfaces and the roughest were those blasted with the largest particles (63-90 microns). The cell profile areas were measured using a semi-automatic interactive image analyzer. The attachment was determined as a ratio of the area of cell profiles and the total micrograph area and was expressed as percentage of attachment. Morphologically, the cells were heterogeneous. In general, the cells had spread well on all titanium surfaces, indicating good attachment to both smooth and rough surfaces. After 1, 3 and 6 h, the percentage of cell attachment did not differ significantly between the surfaces blasted with 63-90 microns and the turned surfaces, but was significantly lower on the surfaces blasted with 45 microns or 45-63 microns particles. After 24 h the surfaces blasted with 63-90 microns particles had a higher rate of cell attachment than all the other surfaces including the controls. It is concluded that attachment and growth of cells originating from human mandibular bone in vitro, are influenced by the micro-texture of the implant surface.

Cell Adhesion↗
PubMed1997

[Light microscopic observation of bone interface of titanium-coated 317L plate screw].

The observational results of bone interface of titanium-coated 317L plate screw and 317L plate screw under light microscope are reported in the present paper. Osseointegration was formed in both kinds of screws after implanting. In the titanium-coated 317L plate screw group, the inflammatory reaction was slighter, the new bone formed earlier in the interface and the bone was combined with the metal tightly, whereas in the uncoated 317L plate screw group, the relationship between the bone and metal was only a state of contact. These indicate that the bone interface and tissue compatibility of titanium-coated 317L plate screw may be better than that of the 317L plate screw.

Animals↗
PubMed2001

Alterations in the adhesion behavior of osteoblasts by titanium particle loading: inhibition of cell function and gene expression.

Total joint replacement prostheses are required to withstand corrosive environments and sustain millions of loading and articulation cycles during their term of implantation. Wear debris generation has been implicated as one of the primary causes of periprosthetic osteolysis and subsequent implant loosening in total joint replacements. Particulate debris consisting of metals, polyethylene, ceramics, and bone cement have each been shown to provoke a biological response in joint tissues. The major cell types within the interfacial granulomatous fibrous tissues consist of fibroblasts, macrophages, lymphocytes, and foreign-body giant cells. Osteoblasts are one of the principal cell types in the bone tissue adjacent to prostheses, maintaining physiologic bone remodeling through the balanced coordination of bone formation and resorption in concert with osteoclasts. To date the phenomenon of osteoblast phagocytosis of titanium particles has been suggested, but has not been sufficiently studied or confirmed. This study seeks to clarify the influence of titanium particles on osteoblast adhesion, deformability, proliferation, and gene expression profile. These studies were accomplished by performing biorheological testing, Northern blot analysis and RNase protection assay. The uptake of metallic particles by the osteoblast resulted in a particle-filament complex formation, which induced a series of variations in cell function. Understanding these variations is critical to expanding our knowledge of implant loosening and elucidating the nature of prosthetic joint failure. This study suggests that the impact of titanium particles on osteoblast function and subsequent implant loosening may have been previously underestimated.

Actin Cytoskeleton↗
PubMed1997

[The influence of basement membrane matrix on the attachment of human gingival epithelial cell to titanium: a scanning electron microscopic study].

In order to investigate the factors which could enhance the integrity of the biological seal between implant and epithelial cells, basement membrane matrigel was coated on the surface of smooth pure titanium. SEM observations showed that the spreading of primary cultured human gingival epithelial cells on Matrigel coated titanium surface was better than that of control groups on the third and the sixth day. This result suggests that the attachment of human gingival epithelial cells to titanium can be enhanced by the basement membrane matrigel.

Biocompatible Materials↗
PubMed1975

Pulmonary deposits of titanium dioxide in cytologic and lung biopsy specimens. Light and electron microscopic x-ray analysis.

Although titanium dioxide (TiO2) is widely used in industry, its biologic effects have not been determined. In the present investigation, open lung biopsy samples and sputum specimens from three former TiO2 factory workers and bronchial aspirations from seven TiO2 factory workers were analyzed by conventional and x-ray microanalytic light and electron microscopic methods. These studies showed that in the alveolar macrophages, lysosomes contained a significant amount of titanium as well as smaller amounts of silicon, aluminum, iron, and potassium. It appeared that titanium dioxide was situated in round or oval-shaped particles whereas silica or silicon compounds were localized in separate, more rectangular structures. There fore, the adverse effects may be induced by such quartz or silicon compounds. The latter are utilized as covering substances in the manufacture of TiO2 pigment.

Adult↗
PubMed2001

Tibial implants: biomechanical and histomorphometric studies of hydroxyapatite-coated and uncoated stainless steel and titanium screws in long-term ovariectomized sheep.

This study was designed to evaluate osteointegration of HA-coated and uncoated titanium and stainless steel screws in the cortical bone of long-term (24 months) ovariectomized sheep (OVX group), in comparison with Sham-aged sheep (control group). The screws were tested biomechanically (extraction torque) and histomorphometrically (affinity index: Al) 12 weeks after their implantation in tibial diaphyses. Tibial cortical bone parameters showed significant differences between the groups, showing a reduction of the selected parameters in the OVX group. ANOVA showed significant effects for both material and ovariectomy factors on obtained extraction torque (material: F=159.26, p < 0.0005; ovariectomy: F=20.04, p < 0.0005) and Al data (material: F=8.04, p < 0.001; ovariectomy: F=7, 17, p < 0.05). In both groups the extraction torque for coated screws of both materials was significantly higher than for uncoated screws, and uncoated titanium had a better extraction torque than uncoated stainless steel. In the OVX group, the HA-coated stainless steel and titanium Al data were significantly higher than uncoated Al data. In conclusion, the biomechanical and histomorphological results obtained suggest employing HA-coated screws in the presence of osteopenic cortical bone.

Animals↗
PubMed2000

The use of titanium mesh in the management of orbital trauma--a retrospective study.

This study examines the use of titanium mesh in the reconstruction of internal orbital defects. The goals of reconstruction when treating orbital fractures include restoration of internal wall continuity and provision of support to the orbital contents. In this way the untoward sequelae of post-traumatic enophthalmos and disturbance of visual acuity are avoided. Autogenous grafts have been the material of choice for most surgeons involved with treatment of these injuries. The major disadvantages of using autologous tissue are the need for a graft donor site, with attendant increases in operative time, prolonged hospitalization, increased postoperative discomfort and problems intrinsic to the donor site wound. The purpose of this report is to present the author's experience with the use of titanium alloplasts in the early repair of traumatic orbital wall fractures. Patients treated at the Townsville General Hospital from July 1, 1997-March 1, 2000 with injuries involving the orbit repaired with titanium mesh or micro-mesh were included in the study.

Adult↗
PubMed2000

Bond strength of prosthodontic luting materials to titanium after localized cyclic loading.

PURPOSE: To establish an in vitro analysis system to evaluate the effect of cyclic loading on the bond strengths and durability of luting materials bonded to titanium. MATERIALS AND METHODS: Machine-milled titanium disks were finished with 600 grit silicon-carbide paper and pairs of disks were bonded together using the five different luting materials. A stainless steel stylus was vertically loaded at a center position (Model 1) or at the border (Model 2) of the specimens with a force of 75.6 N at 7500 cycles/hr. When the stylus contacted the specimen surface through the water slurry of poly(methyl methacrylate) beads, it rotated clockwise up to 15 degrees and counter-rotated. Shear bond strengths were determined 1 hr after bonding, after storage in water at room temperature for 24 hr, and after the loading for 100,000 cycles. RESULTS: The bond strengths of the unfilled adhesive resin and resin-based composite cement (RBC) were significantly higher than those of the glass-ionomer cements. Zinc phosphate cement demonstrated no bonding ability to titanium. After 100,000 cycles, peripheral loading in Model 2 significantly reduced the bond strength of the RBC and glass-ionomer cements, while Model 1 loading did not. The highest and the most durable bonds were obtained with the unfilled adhesive resin in both models.

Adhesiveness↗
PubMed2001

Initial contact angle measurements on variously treated dental/medical titanium materials.

The cell attachment to bioapplicable titanium surfaces is an important parameter in the area of clinical implant dentistry and medicine. A major consideration in designing implants has been to produce surfaces that promote desirable responses in the cells and tissues contacting the implants. In this study, three titanium materials (commercially pure titanium - CPT -, Ti-6Al-4V, and TiNi) were treated mechanically, chemically, mechano-chemically, and thermally to produce concave surfaces with varying roughness. Using four media (distilled water, 1% NaCl aqueous solution, a suspension of human neutrophils, and a suspension of the MG-63 osteoblast-like cells), the initial contact angles were measured. Six readings (three drops each measured by two observers) were collected for each material and for each medium. The interclass correlation coefficients were used for the group comparisons. A one-way analysis of variance (ANOVA) and Tukey's HSD (honestly significant difference) statistical analyses were employed. It was found, for CPT, that (1) statistically, there were no significant differences among four media in contact angles, (2) the contact angle increased linearly with average roughness when the angles were higher than 45 degrees, and (3) the contact angle decreased linearly with roughness when the angle was less than 45 degrees.

Alloys↗
PubMed2001

[A comparative study of friction behaviour matching of natural tooth and new type dental prosthetic materials--titanium].

New type dental prosthetic materials Titanium not only have excellent biocompatibility, better corrosion resistance, appropriate hardness, light density approaching to human skeleton, but also good mechanical properties as those of type II, IV gold alloy recommended by ADAS, and their strength to weight ratio is 1.3 times that of aluminum, 1.5 times that of steel. Friction wear comparative tests of natural living teeth and dental Titanium materials have been carried out against Gr15 steel ball. A reciprocating movement was realized at the modified machine of fretting to simulate the pair of real tooth. The main test parameters were: slip amplitude 500 microns, normal load 20 N, frequency 2 Hz, and number of cycles 5000. The wear behavior results show that titanium is comparatively a prospective dental materials for restoration.

Child↗