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Suppression of osteoblast function by titanium particles.

In order to understand the effect of particulate debris on osteoblast function, we studied the effect of different particles, including titanium and polystyrene, on bone collagen mRNA (messenger RNA) with the use of Northern blot hybridization analysis, and we studied the effect of the particles on the biosynthesis of bone collagen with analysis of 3H-proline incorporation and with the Western blot technique. The steady-state levels of mRNA for procollagens alpha1(I) and alpha1(III) were markedly suppressed in human MG-63 osteoblast-like cells exposed to phagocytosable titanium particles that were smaller than three micrometers. Both titanium and polystyrene particles smaller than three micrometers suppressed the expression of the gene that codes for collagen, and the suppression of the expression of the gene was related to the size but not to the composition of the particles. The biosynthesis of both type-I and type-III collagen also was decreased in cells that had been treated with titanium particles. Neither the viability nor the proliferation of cells was affected by particulate debris. These data indicate that phagocytosable titanium particles can significantly suppress the expression of the gene that codes for collagen in osteoblast-like cells (p < 0.05).

Blotting, Northern↗

Comparison of titanium elastic nails with traction and a spica cast to treat femoral fractures in children.

BACKGROUND: Titanium elastic nails are commonly used to stabilize femoral fractures in school-aged children, but there have been few studies assessing the risks and benefits of this procedure compared with those of traditional traction and application of a spica cast. This prospective cohort study was designed to evaluate these two methods of treatment, with a specific focus on the first year after injury, the period when the treatment method should have the greatest impact. METHODS: Eighty-three consecutive children, six to sixteen years of age, were studied prospectively. Factors that were analyzed included clinical and radiographic data, complications, hospital charges, and outcome data. Outcome and recovery were assessed both with the American Academy of Orthopaedic Surgeons Pediatric Outcomes Data Collections Instrument, version 2.0, and according to a series of important recovery milestones including the time to walking with aids, time to independent walking, time absent from school, and time until full activity was allowed. RESULTS: Thirty-five children (thirty-five fractures), with a mean age of 8.7 years, were treated with traction and application of a spica cast, and forty-eight children (forty-nine fractures), with a mean age of 10.2 years, were treated with titanium elastic nails. All fractures healed, and no child sustained a complication that was expected to cause permanent disability. At one year after the fracture, eighty of the children had acceptable alignment and no inequality between the lengths of the lower extremities. The remaining three children, who had an unsatisfactory result, had been treated with traction and a spica cast. Twelve patients (34%) treated with traction and a cast had a complication compared with ten patients (21%) treated with titanium elastic nails. Compared with the children treated with traction and a cast, those treated with titanium elastic nails had shorter hospitalization, walked with support sooner, walked independently sooner, and returned to school earlier. These differences were significant (p < 0.0001). We could detect no difference in total hospital charges between the two groups. CONCLUSIONS: The results of this prospective study support the recent empiric observations and published results of retrospective series indicating that a child in whom a femoral fracture is treated with titanium elastic nails achieves recovery milestones significantly faster than a child treated with traction and a spica cast. Hospital charges for the two treatment methods are similar. The complication rate associated with nailing compares favorably with that associated with traction and application of a spica cast.

Adolescent↗

Electron microscopic analysis of the bone-titanium interface.

Ten cylindrical implants, made of polycarbonate and covered with a 120-250-nm-thick layer of pure titanium, were implanted into each tibial metaphysis of five rabbits. Observation time was 12 weeks. The implants were surrounded by mature, living bone. No soft tissue intervened between bone and implant at any point. With TEM microscopy the titanium was shown to be bordered by a 20-nm-thick layer of proteoglycans, showing the characteristics of ground substance, and separating the collagen from the implant surface. Cells at the interface were likewise separated from the titanium by such a layer. Hydroxyapatite crystals were observed within the ground substance layer, occasionally seemingly in direct contact with the titanium. Normal mineralization was present 100-500 nm from the implant surface. While this study aims at defining interface anatomy, it also shows that macroscopically smooth-surfaced titanium can readily heal into bone without a soft tissue envelope. This could be of help for materials' choice and design of permanently fixed implants.

Animals↗

Bone fixation of ceramic-coated and fiber titanium implants. A study in weight-bearing rats.

We compared the fixation of glass ceramic-coated titanium and fiber titanium implants using a simple weight-bearing model in rats. The chemical composition of the glass ceramic was similar to 45S5F Bioglass. One hundred and eight male Wistar rats were operated on. A segment of their right tibias was replaced by a disc-shaped implant with a central hole. A stable osteosynthesis was completed by means of an intramedullary nail and a tension band. Thirty-six rats received glass ceramic-coated and 36 fiber titanium implants. In 36 rats osteotomies were performed. All animals survived without complications until scheduled sacrifice at 3, 12 and 26 weeks, postoperatively. The ultimate bending moments of the fiber titanium-bone interfaces and the osteotomies increased with time, and approached the levels of the contralateral, intact tibias at the 12th and 26th week. Also, the ultimate bending stresses increased from the 3rd to 12th week. After 26 weeks the fiber titanium-bone interfaces had reached about 45 per cent, and the osteotomies about 75 per cent of the strength of the intact tibias. All the glass ceramic-coated implants were loose, and at 26 weeks there was no coating left.

Animals↗

Absorption, excretion, and tissue deposition of titanium in sheep.

Titanium metabolism was measured in three 18 kg lambs each fed 450 g chopped hay daily. Two of the lambs were dosed orally and one intravenously with 3 muCi titanium-44 each. Clearance of the intravenous dose was extremely slow; after oral administration, however, no titanium-44 was detected in blood plasma for 48 h. Over 96% of the oral dose was recovered in feces and digestive tract contents. Titanium-44 absorption, estimated from total carcass recovery and by comparison of concentrations in internal organs of orally and intravenously dosed lambs, was less than .5%. Fecal titanium could be a satisfactory index of soil ingestion by grazing ruminants.

Absorption↗

Efficacy of gas purging for titanium casting.

Oxygen density in the melting atmosphere, oxygen uptake, hardness and castability of pure titanium castings were examined to evaluate the efficacy of gas purging in reducing contamination from the melting atmosphere and mold, using a newly developed titanium casting machine in which the double purging process is systematized. The adoption of a double purging operation resulted in an extremely low oxygen density in the melting atmosphere, followed by extremely low oxygen uptake in the casting when compared with the conventional titanium casting machine. When the purging operation was used, the surface hardness was markedly reduced, although there was no difference in castability. From these results, it was suggested that the newly developed titanium casting machine with the double purging operation could produce better titanium castings with less contamination due to the mold and gas impurities in melting atmosphere.

Argon↗

Effects of titanium nitride coatings on surface and corrosion characteristics of Ni-Ti alloy.

The structure of a titanium nitride film coated by arc ion plating on a Ni-50Ti shape memory alloy was characterized by X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the titanium nitride-coated Ni-50Ti alloy was examined in 0.9% NaCl solution by potentiodynamic polarization measurements and a polarization resistance method. XPS spectra showed that the titanium nitride film consisted of three layers, a top layer of TiO2, a middle layer of TiNx (x > 1), and an inner layer of TiN. The passive current density for the titanium nitride-coated alloy was approximately two orders of magnitude lower than that of the polished alloy in the potential range from the free corrosion potential to +500 mV (vs. Ag/AgCl). Pitting corrosion associated with breakdown of the coated film occurred above this potential. The polarization resistance data also indicated that the corrosion rate of the titanium nitride-coated alloy at the free corrosion potential (+50-+100 mV) was more than one order of magnitude lower than that for the polished alloy.

Corrosion↗

Microstructure and corrosion behavior of binary titanium alloys with beta-stabilizing elements.

Binary titanium alloys with the beta-stabilizing elements of Co, Cr, Cu, Fe, Mn and Pd (up to 30%) and Ag (up to 45%) were examined through metallographic observation and X-ray diffractometry to determine whether beta phases that are advantageous for dental use could be retained. Corrosion behavior was also investigated electrochemically and discussed thermodynamically. Some cast alloys with Co, Cr, Fe, Mn, and Pd retained the beta phase, whereas those with Ag and Cu had no beta phase. In some alloys, an intermetallic compound formed, based on information from the phase diagram. The corrosion resistance deteriorated in the TiAg alloys because Ti2Ag and/or TiAg intermetallic compounds preferentially dissolved in 0.9% NaCl solution. On the other hand, the remaining titanium alloys became easily passive and revealed good corrosion resistance similar to pure titanium since their matrices seemed to thermodynamically form titanium oxides as did pure titanium.

Analysis of Variance↗

Biocompatibility of apatite-coated titanium mesh prepared by hydrothermal-electrochemical method.

The hydrothermal-electrochemical method is best suited for producing homogeneous apatite coatings on electro-conductive materials with complicated shape, such as the mesh. This study was undertaken to examine the effect of the apatite coating prepared by this coating method on cell adhesion, proliferation, and differentiation of MC3T3-E1 cells in culture. The cells attached and spread well on the electrochemically deposited apatite on titanium mesh. The number of cells that adhered on the deposited apatite on titanium mesh was much greater than that on the surface without coating, and that it also depended on the morphology of apatites. When alkaline phosphatase activity as well as collagen and osteocalcin of the extracellular matrix were measured, the electrochemically apatite-coated titanium mesh showed higher measurement values than the titanium mesh without coating. These results suggested that the apatite-coated titanium mesh prepared by hydrothermal-electrochemical method has excellent biocompatibility.

3T3 Cells↗

Surface treatments of titanium in aqueous solutions containing calcium and phosphate ions.

Immersion treatment of titanium in aqueous solutions containing various kinds of ion concentrations of calcium and phosphate (pH 5.8, 7.0, and 8.0) were attempted to accelerate calcium phosphate precipitation on titanium in body fluid. The performance was confirmed using scanning electron microscopy, X-ray diffractometry, and Fourier transformed infrared absorption spectrometry with a reflection absorption spectrometer of the specimen immersed in Hanks' solution. Calcium phosphate precipitation on titanium in Hanks' solution is accelerated by the immersion treatment in aqueous solutions containing calcium and phosphate ions. The amount, composition, and shape of calcium phosphate precipitate vary according to the pH and ion concentrations of the solutions in which titanium is immersed. This method is effective for the surface treatment of inside pore narrow space of titanium materials.

Biocompatible Materials↗

Effect of plasma-sprayed hydroxyapatite coating on the osteoconductivity of commercially pure titanium implants.

Formation of a calcium phosphate layer was studied on the surfaces of plasma-sprayed hydroxyapatite (PSHA) and sandblasted commercially pure (cp) titanium in simulated body fluid with ion concentrations similar to those of human blood plasma. The PSHA surface induced the formation of calcium phosphate surface layers, while the precipitation of calcium phosphate on sandblasted cp titanium was not detected. Histologic evaluation of in vivo tests demonstrated that implants with a PSHA coating enabled the growth of bone tissue into gaps with a depth of up to 1 mm without significant formation of intermediate fibrous tissue. In comparison to sandblasted cp titanium, implants with PSHA coating exhibited greater tolerance to unfavorable conditions during healing, such as gaps at the interface or primary instability of the implant. In the case of good primary stability of the implant, filling of the gap with fibrous tissue was observed for sandblasted cp titanium implants over the greater part of the surface of gaps with a depth of 0.3 mm. Direct contact of cp titanium implants with bone was achieved only when the press-fit implantation model was used.

Animals↗

A new titanium fiber mesh-cuffed peritoneal dialysis catheter: evaluation and comparison with a Dacron-cuffed tenckhoff catheter in goats.

OBJECTIVE: We report the development of a new peritoneal dialysis catheter. The purpose of the current study was to evaluate tissue response to this catheter. DESIGN: In our catheter design, the catheter's cuffs are made from sintered titanium fiber mesh instead of the common Dacron material. The catheters were implanted in goats. During the study period, the catheter exit sites were observed once every 2 weeks. After 14 weeks, the catheters and surrounding tissues were processed for histology and analyzed. RESULTS: We observed that catheters with titanium cuffs performed significantly better, compared with a commercial catheter design. Histology showed that titanium fibers evoked a lesser inflammatory response compared with Dacron fibers. In addition, the capsule surrounding the titanium cuff was significantly thinner. CONCLUSIONS: Supported by the obtained results, we conclude that the use of Dacron velour for anchorage of percutaneous catheters has to be reconsidered. Titanium fiber mesh has a great potential for application in percutaneous catheters.

Animals↗

[Comparison of internal fixation with mini-titanium plate and wire osteosynthesis in midface fractures].

OBJECTIVE: To compare clinical results of the internal fixation with wire and the internal fixation with mini-titanium plate in midface fractures. METHODS: By the coronal approach and supplementary incisions, forty patients with midface fractures were treated with wire osteosynthesis or rigid internal fixation (RIF) with mini-titanium plate. RESULTS: A good stability can not he obtained with wire osteosynthesis in the treatment of midface fractures. The supporting bony structure of midface can be reconstructed with mini-titanium plate RIF, which results in a sufficient three-dimensional stability of the fractured segments and an ideal facial configuration Mini-titanium plate RIF is more convenient and reliable than wire osteosynthesis in the difficult operation fields of the infraorbital margin and zygomaticomaxillary suture. CONCLUSION: Mini-titanium plate RIF is the best method for treatment of midface fractures.

Adult↗

Wear of luting materials with titanium retainer.

PURPOSE: The purpose of this study was to investigate the wear resistance of prosthodontic luting materials with a titanium framework by means of an in vitro three-bodied wear-testing device. MATERIALS AND METHODS: The surfaces of flat cast titanium disks were blasted with 50 microns alumina. Placing a 50 microns masking tape on the plane surface, the disks were bonded with five luting materials. The axial surfaces of the bonded disks were ground flat with 600 grit silicon-carbide paper, and then cyclically loaded (75.6 N, 1.2 Hz) by a chewing simulator for 400,000 cycles. The distance between titanium and cement surfaces was measured in micrometers by means of a profilometer to determine delta wear, and the surface texture was evaluated with a scanning electron microscope. RESULTS: The delta wear measurement showed that the resistance of Super-Bond Opaque adhesive was significantly higher than Panavia Fluoro adhesive and Fuji I cement after 400,000 wear cycles. No significant differences were detected among Super-Bond Opaque adhesive, Super-Bond adhesive, and All-Bond adhesive. Visually, continuity with the titanium framework was observed when the titanium disks were luted with resin systems.

Analysis of Variance↗

Mechanical and histological analysis of bone-pedicle screw interface in vivo: titanium versus stainless steel.

OBJECTIVE: To investigate the differences in bone interface between titanium and stainless steel pedicle screws in the lumbar spine. METHODS: Eighteen adult mini-pigs that underwent total laminectomy, posterolateral spinal fusion (L4-L5) were randomly selected to receive stainless steel (9) or titanium pedicle screw devices (9). In both groups, the devices were CCD (Sofamore Danek) type with the same size and shape. The postoperative observation time was 3 months. Screws from L4 were harvested along their long axis of pedicle for histomorphometric study. Bone-screw interface and bone volume from thread were examined using linear intercept techniques. Mechanical testing (torsional test and pull-out test) was performed on the screws from L5. RESULTS: The titanium screw group had a significantly higher maximum torque (P < 0.05) and angle related stiffness (P < 0.05) measured by torsional test. In the pull-out tests, no differences were found between the two groups in relation to the maximum load, stiffness and energy to failure. Direct bone contact with the screw in percentage was 29.4% for stainless steel and 43.8% for titanium (P < 0.05). No differences in the bone purchase between the vertebral body part and pedicle part were found. CONCLUSION: Pedicle screws made of titanium have a better bone-screw interface binding than screws made of stainless steel. Torsional tests are more informative for bone-screw interface study. Pull-out tests seem less valuable when comparing bone purchase of screws made from different materials.

Animals↗

[Influence of surface roughness of pure titanium on accumulation of bacterium].

OBJECTIVE: The aim of this investigation was to evaluate the influence of surface roughness of pure titanium on adhesion of bacterium. METHODS: A total of six edentulous volunteers with healthy oral mucosa participated in an in vivo study. Four kinds of pure Titanium testing pieces with different surfaces were fixed in the polished surface of upper complete dentures and the other in the tissue surface of the dentures. After 6-month wearing the dentures, the amount and species of bacterium adhered on pure Titanium were examined. RESULTS: (1) Individual difference had a significant influence on amount of bacterium adhered on pure Titanium, but had no relation to species of bacterium according to Gram's staining. (2) To the same patient, with the increase of roughness, bacterium adhered on samples improved in amount (P < 0.01), but remained the same in composition. Wrinkly samples collected more bacterium than plane samples and exhibited G- coccus beside G+ coccus. Comparing two samples with same roughness, the one with roughness on the tissue surface of the denture collected less bacterium than that on the polished surface (P < 0.01), and predominantly presented G- rod bacterium and coccus, which was completely different to that on the polished surface. CONCLUSION: From the perspective of benefit to periodontal tissue, plane surface should be adopted when framework of pure Titanium is made, and polishing of the prosthesis after being modified should be paid more attention, especially on the tissue surface.

Bacteria↗

[The effects of the multiple structural layer of Ti-cast on bond of porcelain fused to titanium].

OBJECTIVE: To study the effects of the multiple structural layer of Ti-cast on the bond of porcelain fused to titanium. METHODS: The interfacial state and bond strength of porcelain-titanium were observed by EPM analysis and a shear test. RESULTS: The results showed cracks were observed in the interface of porcelain-titanium in R1 (the group of multiple structural layer of Ti-cast), but there were no cracks in the interface of porcelain-titanium in R2 (the group of removed multiple structural layer from Ti-cast) and R3 (the group of wrought titanium). The width of elemental diffusion layer of R1, R2 and R3 were 29.03 microns, 6.90 microns and 7.01 microns respectively. The shear bond srength of R1, R2 and R3 were 29.45 MPa, 52.75 MPa and 48.32 MPa respectively. There were significant difference in the width of elemental diffusion layer and shear bond strength between R1 and R2, R3 (P < 0.01). CONCLUSION: This investigation indicates that the multiple structural layer of Ti-cast should be removed before firing of porcelain.

Dental Casting Technique↗

[The preliminary study on the oxide film of pure titanium treated by anodic oxidation].

OBJECTIVE: To study the oxide film of pure titanium implant material treated by anodic oxidation and to learn the effect of anodic oxidation on it. METHODS: Six titanium sheets, which were ground, polished and pretreated, were treated by anodic oxidation at 10 v, 24 v or 40 v for 10 minutes and at 24 v for 10 minutes, 40 minutes or 2 hours. The microstructures and the corrosive-resistance of oxide films were studied by means of X-ray diffraction and electro-chemical corrosion. RESULTS: The results of X-ray diffraction showed that the titanic peaks of 2.55 and 2.34 inverted as potential went up. Not many disorderly peaks of titanium oxide were found. And all the peaks of 2.55 and 2.34, 1.25 and 1.23, 1.72 and 1.47 did the same when time went on. Disorderly peaks of titanium oxide first appeared more and then fewer. The open loop potential of the oxide film treated by anodic oxidation moved positively, and polarized current was a 100'th of that of natural oxide film. CONCLUSIONS: The oxide film with a certain color and crystallinity could be controlled by the potential and time. The corrosive-resistance of the oxide film is greatly improved by means of anodic oxidation. It will be the next study how to utilize and adjust the rule of titanium crystal corrosion.

Dental Implants↗