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PubMed2005

Titanium mesh implantation--a method to stabilize the spine and protect the spinal cord following a multilevel laminectomy in the adult rat.

The development of clinically relevant larger spinal cord injury models is in part limited by the possibility of a widened or multilevel laminectomy causing a spinal cord injury from an unstable spine or from compression of the spinal cord by adjacent soft tissues. In the adult rat, we have developed a method to protect the spinal cord and stabilize the spinal column using a titanium mesh implant following a bilateral, multilevel lumbar laminectomy. For this purpose, bilateral and expanded L1-4 laminectomies were performed with or without the use of a titanium mesh to protect the spinal cord and stabilize the spine. Without titanium mesh protection, the rats developed a severe paraparesis or paraplegia, urinary retention, gross anatomical signs of cord compression, and motoneuron loss. In the titanium mesh treatment group, the rats typically maintained a normal gait and lower urinary tract function, normal gross anatomical features of the spinal cord, and normal motoneuron counts. We propose that the use of a titanium mesh implant may assist in the development of clinically relevant larger spinal cord injury and repair models.

Animals↗

PubMed2005

Production, processing and small animal PET imaging of titanium-45.

INTRODUCTION: Titanium-45 was prepared as a tool for elucidation of the mechanism of action of titanium anticancer drugs in vivo using microPET imaging. METHODS: Titanium-45 was produced by the 45Sc(p,n)45Ti nuclear reaction using 14.5 MeV protons. Sufficient yields of 45Ti were produced and separated from the target material with 99.8% radionuclidic purity using a simple, efficient separation procedure. RESULTS: A typical bombardment of 5 microA for 1 h produced an average of 2105+/-150 MBq (56.9+/-4.0 mCi) at the end of bombardment (EOB), well within acceptable range of the calculated theoretical yields of 2165 MBq and 433 MBq microA-1 h-1 (58.5 mCi and 11.7 mCi microA-1 h-1). This amount of activity is sufficient for the radiosynthesis of target compounds as well as imaging studies. MicroPET images of a miniature Derenzo phantom show excellent resolution where rods of 1.25 mm were separated by four times their diameter. CONCLUSIONS: Titanium-45 can be easily produced on a biomedical cyclotron with excellent yields as compared to calculated theoretical values with imaging studies demonstrating that the decay properties of titanium-45 are well suited for microPET.

Animals↗

PubMed2005

Safety evaluation of titanium middle ear prostheses at 3.0 tesla.

OBJECTIVE: To assess the magnetic resonance imaging (MRI) safety of titanium middle ear prostheses at 3.0 tesla (T). STUDY DESIGN AND SETTING: Titanium middle ear prostheses from 3 commercial vendors were examined for magnetic field interactions at 3 T. Initially, ex vivo studies were performed to test for rotational motion and forward displacement (translational motion) of the prostheses in a static magnetic field. If movement was observed during this screening study, then the prosthesis was tested to determine the translational or rotational force acting upon the prosthesis. In addition to testing for prosthesis displacement, temperature changes of the prostheses were measured to assess for radiofrequency heating during imaging. RESULTS: Twenty-one of the 24 titanium prostheses tested revealed no movement when tested in the 3 T static magnetic field. Three prostheses revealed minimal movement during the screening study. A translational force test (string test) was performed upon these 3 prostheses, and the measured angle of displacement was used to determine the force. This calculated force acting upon each prosthesis was essentially zero. Therefore, we conclude that the magnetic field interaction is negligible. A positive control with a ferromagnetic stainless steel prosthesis demonstrated obvious displacement during the screening study, as well as deflection of the prosthesis by 90 degrees in the translational force test. Last, heating of the titanium prostheses did not occur in the 7 models tested. CONCLUSIONS: Middle ear prostheses made from titanium are safe, neither deflecting nor heating during magnetic resonance examinations conducted at 3 T. EBM RATING: C-1.

Equipment Failure Analysis↗

PubMed2004

Evaluation of shear bond strength at the interface of two porcelains and pure titanium injected into the casting mold at three different temperatures.

STATEMENT OF PROBLEM: Titanium has physical and mechanical properties, which have led to its increased use in dental prostheses despite casting difficulties due to high melting point and formation of oxide layers which affect the metal-ceramic bond strength. PURPOSE: This in vitro study evaluated the shear bond strength of the interface of 2 dental porcelains and pure titanium injected into a mold at 3 different temperatures. MATERIAL AND METHODS: Using commercially pure (cp) titanium bars (Titanium, Grade I) melted at 1668 degrees C and cast at mold temperatures of 430 degrees C, 700 degrees C or 900 degrees C, 60 specimens were machined to 4 x 4 mm, with a base of 5 x 1 mm. The 4-mm surfaces were airborne-particle abraded with 100 microm aluminum oxide before applying and firing the bonding agent and evaluating the 2 porcelains (Triceram/Triline ti and Vita Titankeramik). Ten specimens were prepared for each temperature and porcelain combination Shear bond testing was performed in a universal testing machine, with a 500-kg load cell and crosshead speed of 0.5 mm/min. The specimens were loaded until failure. The interfaces of representative fractured specimens of each temperature were examined with a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Data for shear bond strength (MPa) were statistically analyzed by 2-way ANOVA and the Tukey test (alpha=.05). RESULTS: The results showed significant differences for the metal/porcelain interaction effect (P=.0464). There were no significant differences for the 2 porcelains (P=.4250). The Tukey test showed a significant difference between the pair cp Ti 430 degrees C Triceram and cp Ti 900 degrees C Triceram, with respective mean values and SDs of 59.74 +/- 11.62 and 34.03 +/- 10.35 MPa. CONCLUSION: Triceram porcelain showed a bond strength decrease with an increase in the mold temperature for casting titanium. The highest bond strength for Vita porcelain and the best metal-ceramic interface observed with the SEM were found with the mold temperature of 700 degrees C.

Air Abrasion, Dental↗

PubMed2006

Influence of investment type and sprue number on the casting accuracy of titanium crown margins.

STATEMENT OF PROBLEM: Titanium offers biocompatibility and adequate mechanical properties for fabricating dental prostheses; however, casting difficulties can compromise the accuracy of titanium crown margins. PURPOSE: The aim of this study was to evaluate the influence of investment type and number of sprues on accuracy of crown castings made with commercially pure titanium. MATERIAL AND METHODS: The casting accuracy was evaluated indirectly by determining the deficiency of titanium crown margins cast using the lost-wax technique. Crown margins were recorded in a silicone impression material. The degree of marginal rounding was measured and margin deficiencies were calculated. Seventy-five acrylic resin crown patterns with wax margins were prepared on a stainless steel stylized crown die having a 30-degree beveled finish line. Fifteen patterns were selected for the control group, and the degree of wax margin rounding was determined (group W, control). The remaining 60 were divided into 4 groups of 15 each, and cast using 2 different titanium investments: a monoammonium dihydrogenphosphate-bonded investment (Rematitan Plus; groups PI and PII), and a magnesium oxide-bonded investment (Rematitan Ultra; groups UI and UII). Each pattern was cast with either 1 (groups PI and UI) or 2 (groups PII and UII) sprues. Margin configurations for both wax pattern and cast specimens were measured and recorded with the same method, using silicone impressions of the margins. After polymerization, the silicone material was sectioned precisely in 8 locations through the margin area so that cross-sections of the margins could be observed. Marginal deficiency was determined using microscopic measurements from the silicone patterns and calculations. Data were subjected to 2-way analysis of variance (alpha=.05). RESULTS: Specimens from group W presented a mean marginal deficiency of 19 +/- 6 microm. The analysis of variance indicated a significant difference for the main factors, investment (P<.01) (P=91 +/- 28 microm and U=78 +/- 17 microm) and sprue number (P<.001) (I=97 +/- 23 microm and II=72 +/- 16 microm), as well as for interaction (P<.05) (PI=109 +/- 25 microm; PII=73 +/- 17 microm; UI=85 +/- 15 microm; and UII=71 +/- 16 microm). CONCLUSION: Within the limitations of this study, investment U provided better casting accuracy than investment P. Two sprues provided more accurate results than 1 sprue; however, this effect was more notable for investment P, as it produced similar results between groups PII and UII.

Analysis of Variance↗

PubMed2006

Evaluation of welded titanium joints used with cantilevered implant-supported prostheses.

STATEMENT OF PROBLEM: Early failure of laser-welded titanium implant frameworks in clinical practice has prompted an investigation of the strength and durability of welded cantilevered titanium sections. PURPOSE: The purpose of this study was to determine the effect that the use of filler wire in laser welding of titanium cantilever frameworks had on the flexural strength and fatigue resistance of the welded joints. MATERIAL AND METHODS: Sixty titanium implant-supported frameworks with 12-mm cantilevers were fabricated in 4 groups (n=15), using 3 different laser welding protocols with 0, 1, and 2 weld passes with filler wire, and 1 conventional tungsten inert gas welding method. The volume of filler wire used (mean volumes 0, 1.7, 3.4, and 8.3 mm(3)) was determined by measurement of the length of wire before and after welding each joint. Ten frameworks from each group were tested for ultimate flexural strength by loading the cantilevers 10 mm from the abutment. The remaining 5 frameworks from each group were similarly tested under a simulated masticatory load of 200 N until failure, or to 1 million cycles. A 2-way analysis of variance was used to examine the flexural strengths, and log-rank statistics were applied to cyclic test data (alpha=.05). RESULTS: There were significant differences between the 4 groups for ultimate flexural strength (P<.001) and resistance to cyclic loading (P=.002). The volume of filler wire added was a significant predictor of ultimate flexural strength (P=.03), and was a borderline determinant of the number of cycles to failure at 200 N (P=.05). Each laser weld pass with filler wire roughly doubled the ultimate flexural strength and fatigue resistance of the joint relative to the previous weld. Tungsten inert gas welding with efficient argon shielding deposited the most filler wire and produced the strongest and most fatigue-resistant joints. CONCLUSION: The ultimate flexural strength and fatigue resistance of cantilevered joints in laser-welded titanium prostheses are improved by the use of filler wire. Tungsten inert gas welding with efficient argon shielding can be used in situations when a high-strength joint is required.

Analysis of Variance↗

PubMed1995

Mechanical properties of laser-welded cast and wrought titanium.

This study evaluated the mechanical properties of laser-welded cast and wrought titanium base and compared them with those of a brazed type IV casting gold alloy. Ultimate tensile strength, 0.2% yield strength, and percent elongation were recorded for joined and unjoined bars of the previously mentioned materials. Sections of titanium bars were laser-welded, and gold alloy bars were brazed. Both joining methods significantly reduced the ductility of the material. The strength of the cast gold alloy was superior to that of titanium. However, the strength of the laser-welded titanium equaled that of the brazed gold alloy, which suggests that dental restorations made of cast and wrought titanium would satisfy ordinary clinical requirements.

Analysis of Variance↗

PubMed1997

Lipopolysaccharide affinity for titanium implant biomaterials.

STATEMENT OF PROBLEM: Lipopolysaccharide (LPS) affinity for titanium implant biomaterials could affect crevicular LPS concentrations and thereby influence periimplant inflammation. PURPOSE OF STUDY: The purpose of this study was to evaluate Porphyromonas gingivalis and Escherichia coli LPS affinity for titanium biomaterials groups that differed in surface oxide composition and surface roughness. MATERIAL AND METHOD: Polished and abraded grade 1 commercially pure titanium and grade 5 alloyed extra low interstitial titanium specimens were treated with 10 EU/mm2 and radiolabeled LPS. RESULTS: The resultant mean +/- SD LPS adherence values ranged from 4.17 +/- 0.29 to 4.79 +/- 0.40 EU/ mm2. No difference in adherence and elution was indicated on the basis of LPS type, surface oxide composition, or surface roughness. Moreover, P. gingivalis and F. coli LPS desorption was below detection. CONCLUSION: Clinically, the high affinity of both LPS types for titanium biomaterials may adversely influence the periimplant tissue response.

Adsorption↗

PubMed1998

Mechanical properties of laser-welded cast titanium joints under different conditions.

STATEMENT OF THE PROBLEM: Data on optimal conditions for laser welding commercial pure cast titanium used in dental restorations are sparse and not well established. PURPOSE: The mechanical properties of laser-welded cast commercially pure titanium under different laser welding conditions were evaluated to find the optimal parameters in terms of duration and voltage (energy level). MATERIAL AND METHODS: Fifty-seven cast pure titanium specimens according to ISO specification 6871 were divided into nine experimental groups and one control group. The sectioned titanium bars were laser-welded under different duration (8, 10, and 12 ms) and energy (290, 300, and 310 V) levels and evaluated for ranges of ultimate tensile strength (374 to 562 MPa), 0.2% yield strength (206 to 338 MPa), and percentage elongation (2.49% to 10.58%). RESULTS: Under a suitable laser-welding setting parameter the ultimate tensile strength and 0.2% yield strength of experimental groups were weaker than the unsectioned control specimens (control group ultimate tensile strength 540 +/- 11 MPa, 0.2% yield strength 258 +/- 49 MPa) or too brittle (control group percentage elongation 12.41% +/- 1.83%). Two-way ANOVA, nonparametric tests showed that voltage was the only significant factor for all parameters studied (p < 0.01). Optimal conditions were determined with three-dimensional response curves (305 V, 12 ms ultimate tensile strength; 310 V, 10 ms 0.2% yield strength; 300 V, 12 ms percentage elongation). CONCLUSION: Optimal duration and voltage (energy level) used in laser welding for cast CP grade I titanium bar was superior to or comparable with and produced properties that were superior to or comparable with the unsectioned control specimens.

Analysis of Variance↗

PubMed1998

Thermal modeling of laser welding for titanium dental restorations.

STATEMENT OF PROBLEM: Concerns of laser welding for titanium dental prostheses are the limited depth of laser beam penetration and extensive surface damage. PURPOSE: This study used numerical heat transfer simulation to explain this behavior and offers an alternate multiple-pulsed method. MATERIAL AND METHODS: A one-dimensional finite difference analysis was used to simulate heat transfer in pure titanium and gold during laser welding with a custom-constructed software program. RESULTS: The thermal gradient profiles revealed the problem to be inherent in titanium's low thermal conductivity; gold did not have this problem. Time-elapsed multiple pulses on titanium relieved this problem by giving the energy time to diffuse into the depth of the material. CONCLUSIONS: With single-pulse laser irradiation on titanium, an increase in power could not greatly increase melting depth. The excess energy only vaporized the material surface.

Computer Simulation↗

PubMed2002

Use of titanium staples during upper tract laparoscopic reconstructive surgery: initial experience.

PURPOSE: Using nonabsorbable titanium staples in the lower urinary tract during laparoscopic nephroureterectomy has been shown to be safe. Laboratory studies of titanium staples in the upper urinary tract have likewise been favorable. Therefore, we used titanium Endo-GIA tissue staples (United States Surgical, Norwalk, Connecticut) to facilitate laparoscopic reduction pelvioplasty during laparoscopic pyeloplasty. MATERIALS AND METHODS: Of the 17 cases of reduction pelvioplasty closure was done in 12 using absorbable sutures, while in 5 reduction was done with an Endo-GIA stapler. Followup consisted of office visits and telephone interviews plus radionuclide renal scans. RESULTS: Average operative time was 5.5 hours in the Endo-GIA group compared with 6.8 hours in the sutured group. In the latter group extravasation in 2 patients postoperatively was managed conservatively. There was no extravasation in the stapled group. At a median subjective followup of 27 months none of the 5 patients who underwent reduction with titanium staples had symptomatic nephrolithiasis, although new onset urolithiasis developed in 1 in the sutured group. All patients had a greater than 50% decrease in pain. Renal scans at a median of 9 months showed that all ureteropelvic junction repairs were unobstructed. Additional radiographic studies in 2 patients in the stapled group showed a patent ureteropelvic junction and no stones. CONCLUSIONS: Titanium staples provide rapid, secure closure of the renal pelvis during laparoscopic pyeloplasty. While the risk of stone formation is an ongoing concern, it has yet to materialize.

Adult↗

PubMed1998

Evaluation of restorative and implant alloys galvanically coupled to titanium.

OBJECTIVES: As the success of implants leads to their increasing use in restorative dentistry, attention should be devoted to the galvanic combination of restorative materials with titanium. This paper used continuous corrosion potential monitoring in conjunction with zero-resistance ammetry to obtain galvanic corrosion properties of restorative and implant materials coupled with titanium (ASTM F67-Grade II). METHODS: Direct coupling or galvanic experiments were conducted on eight restorative and implant materials coupled to titanium. Deaerated artificial saliva solution in a specifically designed corrosion cell simulated an oral crevice situation. Open circuit potentials (Eo.c.) of each material in the couple, coupled corrosion potentials (Ecouple corr), coupled corrosion current density (lcouple corr) and the resultant charge transfer were monitored. The results were analyzed using single factor ANOVA and Duncan's multiple range tests. RESULTS: Noble restorative (Au-, Ag-, and Pd-based) alloys coupled to titanium were found to be least susceptible to galvanic corrosion. Co-Cr-Mo, Ni-Cr and Fe-based alloys coupled to tatanium were found to be moderately susceptible to galvanic corrosion due to mechanical-electrochemical interaction. Ni-Cr-Be alloy coupled to titanium was found to be highly susceptible to galvanic corrosion. The in vitro test results for the titanium/Disperalloy combination does not concur with the published clinical performance of this combination, and thus warrants further investigation. SIGNIFICANCE: From the data obtained in this study and current literature profiles, acceptable restorative couples were developed for use as clinical guidelines in restorative dentistry.

Analysis of Variance↗

PubMed2000

Scanning electron microscopical analysis of laser-treated titanium implant surfaces--a comparative study.

Design and surface qualities of titanium implants are of vital importance for long-term stability following implantation. Four different implant surfaces treated individually were analyzed with special attention focused on laser surface treatment. Surfaces with machine roughness, titanium spray coating, treated by aluminum oxide and treated by laser were examined individually. Evaluation of the surface was carried out by electron microscope examination and mechanical profilometry. The EDS analysis determined the degree of contamination of the implant surface. Electron microscope examination showed that the titanium plasma spray as well as the laser-treated implants have optimum surface qualities: a secondary and tertiary structure with micro-roughness of 10 mm and roughness ranging from 0.5 to 4 mm. The least contamination was found for machine rough surfaces as well as those treated by laser. The other implants showed contamination corresponding to the method of surface treatment. In summary the optimal surface structure with the least contamination was found for the laser-treated titanium surface. Similar surface purity was found for the machine rough surfaces. An optimal structure was also achieved by the titanium plasma spray method, however, at the cost of surface purity.

Aluminum Oxide↗

PubMed2000

Bone formation in calcium-phosphate-coated titanium mesh.

The osteogenic activity of porous titanium fiber mesh and calcium phosphate (Ca-P)-coated titanium fiber mesh loaded with cultured syngeneic osteogenic cells was compared in a syngeneic rat ectopic assay model. In 30 syngeneic rats, (Ca-P)-coated and non-coated porous titanium implants were subcutaneously placed either without or loaded with cultured rat bone marrow (RBM) cells. Fluorochrome bone markers were injected at 2, 4, and 6 weeks. The rats were sacrificed, and the implants were retrieved at 2, 4, and 8 weeks post-operatively. Histological analysis demonstrated that none of the (Ca-P)-coated and non-coated meshes alone supported bone formation at any time period. In RBM-loaded implants, bone formation started at 2 weeks. At 4 weeks, bone formation increased. However, at 8 weeks bone formation was absent in the non-coated titanium implants, while it had remained in the (Ca-P)-coated titanium implants. Also, in (Ca-P)-coated implants more bone was formed than in non-coated samples. In general, osteogenesis was characterized by the occurrence of multiple spheres in the porosity of the mesh. The accumulation sequence of the fluorochrome markers showed that the newly formed bone was deposited in a centrifugal manner starting at the center of a pore. Our results show that the combination of Ti-mesh with RBM cells can indeed generate bone formation. Further, our results confirm that a thin Ca-P coating can have a beneficial effect on the bone-generating properties of a scaffold material.

Animals↗

PubMed2001

Titanium metals form direct bonding to bone after alkali and heat treatments.

In this article we evaluated the bone-bonding strengths of titanium and titanium alloy implants with and without alkali and heat treatments using the conventional canine femur push-out model. Four kinds of smooth cylindrical implants, made of pure titanium or three titanium alloys, were prepared with and without alkali and heat treatments. The implants were inserted hemitranscortically into canine femora. The bone-bonding shear strengths of the implants were measured using push-out test. At 4 weeks all types of the alkali- and heat-treated implants showed significantly higher bonding strength (2.4-4.5 MPa) than their untreated counterparts (0.3-0.6 MPa). At 12 weeks the bonding strengths of the treated implants showed no further increase, while those of the untreated implants had increased to 0.6-1.2MPa. Histologically, alkali- and heat-treated implants showed direct bonding to bony tissue without intervening fibrous tissue. On the other hand, untreated implants usually had intervening fibrous tissue at the interface between bone and the implant. The early and strong bonding to bone of alkali- and heat-treated titanium and its alloys without intervening fibrous tissue may be useful in establishing cementless stable fixation of orthopedic implants.

Alkalies↗

PubMed2001

The titanium surface texture effects adherence and growth of human gingival keratinocytes and human maxillar osteoblast-like cells in vitro.

The adhesion, orientation and proliferation of human gingival epithelial cells and human maxillar osteoblast-like cells in primary and secondary culture were studied on glossy polished, sandblasted and plasma-sprayed titanium surfaces by scanning electron microscopy and in thin sections. The primary cultured explants of human gingival epithelial cells attached, spread and proliferated on all titanium surfaces with the greatest extension on the polished and the smallest extension on plasma-sprayed surfaces. In secondary suspension cultures of gingival keratinocytes, attachment spreading and growth was only observed on polished and plasma-sprayed surfaces, but not on sandblasted surfaces. Moreover, the attachment of these cells depended on the seeding concentration as well as on the coating with fetal calf serum. Cells on polished surfaces developed an extremely flat cell shape, but on sandblasted and plasma-sprayed surfaces a more cuboidal shape. In contrast human maxillar osteoblasts seeded as secondary suspension cultures attached very well to all three differently textured titanium surfaces and showed identical growth patterns independent of the titanium surface structure. These findings suggest that cell morphology, orientation, proliferation and adhesion of human gingival epithelial cells in primary or secondary culture are dependent on the texture of the titanium surface whereas no such differences were observed for maxillar osteoblast-like cells. In conclusion, the soft tissue integration and response is more influenced by the surface texture than the process of osseointegration.

Alkaline Phosphatase↗

PubMed2002

Morphological behavior of osteoblast-like cells on surface-modified titanium in vitro.

In recent papers, we reported the results of a study on the graded porous titanium coatings on titanium by plasma spraying and amino-group ion implantation. The paper is to preliminarily evaluate the biocompatibility of surface-modified titanium through 2, 5 and 7 days cell culture in vitro. Cell morphology was observed by a scanning electron microscope. Cell proliferation and type I collagen synthesis were measured by 3(4.5-dimethyl-thiazole-2-yl)2,5-diphenyl tetrazolium bromide (MTT) and enzyme-linked immunosorbent assay (ELISA), respectively. Our experimental results showed that osteoblast-like cells attached and spread well on surface-modified titanium. Cells were observed to grow into the pores and form extracellular matrix. MTT and ELISA results showed no detrimental effect on the development of cell. These studies support the biocompatibility of surface-modified titanium.

3T3 Cells↗

PubMed2002

Influence of fluoride content and pH on the corrosion resistance of titanium and its alloys.

In the last decade, new titanium alloys have been developed in different areas of dentistry, such as TiAl6V4 and NiTi. Concurrently, treatments using fluoride supplementation, such as odontology fluoride containing gels, have also been widely used in odontology. The aim of this study was to compare the NiTi, NiTiCo and TiAl6V4 alloys with the titanium, regarding the corrosion resistance in Fusayama Meyer artificial saliva with different pH and fluoride contents. In the experimental methods, the corrosion potential was measured over time, then a linear sweep voltametric analysis measured the polarization resistances and corrosion currents. Our results have shown that TiAl6V4 alloys have a good corrosion resistance as good as that of titanium in Fusayama Meyer saliva and acid salivary solution, except NiTi and NiTiCo alloys. Conversely, we noticed, as for the titanium, a remarkable localized corrosion phenomenon of those new alloys in fluoride and acid-fluoride salivary solutions. The fluoride ions could cause the breakdown of the protective passivation layer that normally exists on the titanium and its alloys, leading to pit corrosion.

Alloys↗