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PubMedDate not supplied

4-META polymethyl methacrylate shear bond strength to titanium.

Machined titanium substructures for fixed, complete arch prostheses have been used with various surface pretreatments to enhance acrylic bonding. Since traditional mechanical methods for denture base material retention cannot be used, silane and surface abrasives have been used to enhance retention. The purpose of this study was to determine if a metal bonding denture base material provided a favorable bond strength to machined titanium. Fifteen rod-shaped samples of commercially pure Grade 2 titanium were divided into two groups, five samples representing the control group and 10 samples for the experimental group. The rod samples for the control received no pretreatment, while the experimental samples were pretreated with 110 microns alumina abrasive. Meta-Dent heat-cured polymethyl methacrylate was processed around each sample in a secondary cylindrical shape approximately 0.9 x 1.0 centimeters with the titanium rods extending from each end. A Shell-Nielsen shear test was then performed at a crosshead speed of 0.5 millimeters/minute to determine the bond strength. The experimental group demonstrated a mean bond strength 3.7 times greater than the control group (significant, P = 0.0001, ANOVA). Pretreatment with 110 microns alumina air abrasive significantly enhanced the bond strength of heat-cured metal bonding polymethyl methacrylate to titanium.

Acrylic Resins↗
PubMedDate not supplied

Osteoblast responses to BMP-2-treated titanium in vitro.

In this study, the phenotypic expression of osteoblast progenitor cells, 2T9, on characterized titanium surfaces was examined in the presence of a bone morphogenetic protein-2 (BMP-2). X-ray photoelectron spectroscopy spectra indicated the presence of titanium dioxide on titanium surfaces, along with surface contaminants such as carbon and nitrogen. In the in vitro study, the activity of BMP-2-treated osteoblast cells on titanium surfaces was marked by significantly higher alkaline phosphatase-specific activity and 1,25 (OH2) vitamin D3-stimulated osteocalcin production when compared to the untreated cells on titanium surfaces.

Alkaline Phosphatase↗
PubMedDate not supplied

Cobalt-chromium-titanium alloy for removable partial dentures.

Pure elemental titanium was alloyed with cobalt and chromium in dilutions of 4%, 5%, and 6% to evaluate the suitability of the resulting alloy for removable partial denture frameworks. The physical properties of the Co-Cr-Ti alloy were compared to the properties of a commercial pure titanium and Vitallium. Clasp replicas were cast in Co-Cr-Ti and Vitallium and subjected to cyclic deflection. Representative specimens from the fatigue failure tests were then evaluated using scanning electron microscopy and analyzed for elemental content. The 5% titanium dilution of cobalt-chromium proved to have the best physical properties and was used for comparison with the pure titanium and Vitallium. The Co-Cr-5% Ti had significantly better physical properties than pure titanium and a greater flexure fatigue limit than the Vitallium alloy.

Chromium Alloys↗
PubMed1994

The effect of titanium on the growth of plaque micro-organisms in vitro.

The effect of titanium on the growth of plaque organisms was studied in vitro. Thioglycollate broth containing either titanium or glass cylinders was inoculated with plaque micro-organisms and incubated aerobically and anaerobically at 37 degrees C for 6 hours. Growth was measured by observing an increase in turbidity of the broth. Cultures grew more vigorously aerobically than anaerobically. In the presence of titanium there was also more growth aerobically than anaerobically. There was no significant difference between the turbidity values obtained in the presence or absence of titanium suggesting that titanium does not influence the growth of plaque micro-organisms significantly.

Agar↗
PubMedDate not supplied

Two years of clinical experience with Procera titanium crowns.

PURPOSE: The purpose of the study were to evaluate the clinical performance of the Procera porcelain-fused-to-titanium crown system in general practice during a 2-year period, and to evaluate the performance of a new low-fusing porcelain as a veneering material on titanium. MATERIALS AND METHODS: A number of consecutive complete-coverage crowns (40) in 25 patients (14 women and 11 men) with a mean age of 53.1 years (range 35 to 79 years) were made according to the Procera (Nobel Biocare) technique in a 3-month period. The titanium copings were fabricated from solid rods of pure titanium using spark erosion and copy-milling technique, whereafter they were veneered with a new type of low-fusing ceramic material. The crowns were evaluated using the CDA criteria at baseline and after 2 years. RESULTS: The general failure rate was low and was restricted to one carious lesion, one porcelain fracture, and one loss of a crown resulting from failure of retention of a post and core. The most frequent single reason that the "excellent" color level was not recorded was a "too-high value." A slightly dull or granular porcelain surface was observed both at baseline and after 2 years. Overall, the responses of the patients were positive. CONCLUSION: Within the limitations of the study it can be concluded that porcelain-veneered Procera titanium crowns can be used as an alternative to other porcelain-fused-to-metal systems. However, conclusions should be made with caution from the results of this study because of the limited number of patients and crowns and the short observation period.

Adult↗
PubMed1998

Titanium as an ossicular replacement material: results after 336 days of implantation in the rabbit.

OBJECTIVE: Titanium in other parts of the body, well known for its biocompatibility, was examined in an animal model for its use as an ossicular replacement material. STUDY DESIGN: The biocompatibility of titanium was studied in the middle ear of rabbits using light and scanning electron microscopy. Titanium pins were placed as middle ear prostheses or as free implants and were examined after 28, 84, 168, and 336 days. RESULTS: After 28 days, the prostheses were covered by regular mucosa. The free implants took up to 336 days to be totally epithelialized. There were no inflammatory cells observed on the surface of the material nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. CONCLUSIONS: The results of this animal experiment indicate that titanium is a useful material for ossicular replacement prostheses.

Animals↗
PubMed2005

Structural effects of titanium citrate on the human erythrocyte membrane.

The structural effects of titanium citrate on the human erythrocyte membrane were studied through its interaction with intact erythrocytes and isolated unsealed human erythrocyte membranes (IUM). The studies were carried out by scanning electron microscopy and fluorescence spectroscopy, respectively. Titanium citrate induced shape changes in erythrocytes, which were damaged and ruptured leaving empty and retracted membranes. Fluorescence spectroscopy measurements in IUM indicated a disordering effect at both the polar head group and the acyl chain packing arrangements of the membrane phospholipid bilayer. Titanium citrate also interacted with molecular models of the erythrocyte membrane consisting in bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representing classes of phospholipids located in the outer and inner monolayers of the erythrocyte membrane, respectively. X-ray diffraction indicated that titanium citrate induced structural perturbation of the polar head group and of the hydrophobic acyl regions of DMPC, while the effects on DMPE bilayers were negligible. This conclusion is supported by fluorescence spectroscopy measurements on DMPC large unilamellar vesicles. All these findings indicate that the structural perturbations induced by titanium to human erythrocytes can be extended to other cells, thereby affecting their functions.

Acylation↗
PubMed1995

A comparison of canal preparation with nickel-titanium and stainless steel instruments.

Maintaining the original canal path during instrumentation is a challenge in narrow curved canals. This study compared the maintenance of the original canal path of curved root canals during instrumentation with nickel-titanium (Mac) hand files, nickel-titanium engine-driven files, and stainless steel (K-Flex) files. Canal path maintenance was determined by superimposing instrumentation radiographs over an initial file radiograph and examining for discrepancies. Nickel-titanium hand and engine-driven instruments maintained the original canal path in all cases. The incidence of deviation from the original canal path during instrumentation with stainless steel files increased with file size. The difference between nickel-titanium groups and stainless steel became statistically significant with instruments larger than size 30. In this study, nickel-titanium files were more effective in maintaining the original canal path of curved root canals when the apical preparation was enlarged beyond size 30.

Alloys↗
PubMed1999

A clinical and histologic prospective controlled comparative study of the picosecond titanium:sapphire (795 nm) laser versus the Q-switched alexandrite (752 nm) laser for removing tattoo pigment.

BACKGROUND: Theory predicts that picosecond lasers should be more effective than the currently available nanosecond lasers in removing tattoo ink. In addition to thermal confinement, such pulse widths cause optimal photomechanical disruption of the target. OBJECTIVE: This study compared the efficacy of the picosecond titanium:sapphire (795 nm, 500 psec) laser and the Q-switched alexandrite (752 nm, 50 nsec) laser in the treatment of tattooed guinea pigs. METHODS: Six albino guinea pigs, each with 6 uniformly 1 cm circular black tattoos, were treated. Three of the tattoos were divided into 2; one half was treated with the titanium:sapphire laser and the other half with the alexandrite laser. Fluences used for both lasers were 6.11, 4.24, and 2.39 J/cm2 with spot sizes of 1.25, 1.5, and 2 mm, respectively. The remaining spots served as control. Clinical evaluation and biopsies were performed at baseline and at 11 and 16 weeks after a single laser treatment. RESULTS: Greater clearance of tattoo was observed in titanium:sapphire laser-treated areas in 2 of the 4 surviving guinea pigs. In some areas total clearing was observed after the single titanium:sapphire laser treatment. Clearing improved with higher fluences. No scarring was present. Histologic results showed similar findings. CONCLUSION: Our findings suggest that the picosecond titanium:sapphire laser is more effective than the Q-switched alexandrite laser in removing tattoo pigment and may be of significant clinical utility.

Animals↗
PubMed2000

Surface hardness changes induced by O-, Ca- or P-ion implantation into titanium.

Titanium or titanium alloys are very attractive biomedical materials. Biocompatible elements of oxygen, calcium and phosphorus were implanted into titanium and changes of surface hardness were measured using an ultra micro indenter (UMIS-2000). A multiple load-partial unload procedure that can reveal a hardness versus depth profile was adopted. Depth profiles of concentration of implanted ions were obtained by SIMS measurement. For O and P implantation, it is observed that the hardness increases with the increases in the dose. O implantation produced the largest increase in hardness, up to 2.2 times higher than the unimplanted titanium. On the other hand, Ca implantation produced only a small increase in the hardness that was independent of the ion dose. The surface oxide layer of a Ca implanted titanium sample was much thicker than the unimplanted samples or those implanted with O and P ions. The depth of maximum hardness increases with increasing energy of implanted ions. The depths of the maximum hardness occur at indentation depths of one-third to one-eighth of the mean ranges of implanted ions.

Journal Article↗
PubMed1998

Structural Aspects of the Dehydration and Dehydroxylation of gamma-Titanium Phosphate, gamma-Ti(PO(4))(H(2)PO(4)).2H(2)O.

The thermal transformations of gamma-titanium phosphate, gamma-Ti(PO(4))(H(2)PO(4)).2H(2)O, have been studied using thermogravimetric analysis, differential scanning calorimetry, X-ray powder diffraction, and temperature-resolved in-situ powder diffraction. The transformation sequence goes from gamma-Ti(PO(4))(H(2)PO(4)).2H(2)O over a new partially dehydrated form gamma'-Ti(PO(4))(H(2)PO(4)).(2-x)H(2)O (x approximately 1) to the anhydrous form beta-Ti(PO(4))(H(2)PO(4)) and then through a two-step condensation process where layered titanium pyrophosphate, Ti(PO(4))(H(2)P(2)O(7))(0.5), is formed first and finally cubic titanium pyrophosphate TiP(2)O(7). The dehydration of gamma-Ti(PO(4))(H(2)PO(4)).2H(2)O and the dehydroxylation/condensation process from beta-Ti(PO(4))(H(2)PO(4)) to layered titanium pyrophosphate,Ti(PO(4))(H(2)P(2)O(7))(0.5), was followed in-situ. A new partially dehydrated phase, gamma'-Ti(PO(4))(H(2)PO(4)).(2-x)H(2)O (x approximately 1), which forms at approximately 50 degrees C has been detected and characterized. The unit cell is monoclinic with the lattice parameters a = 23.670(1) Å, b = 6.264(1) Å, c = 5.036(1) Å, beta = 102.41(1) degrees, and Z = 4. Layered titanium pyrophosphate, Ti(PO(4))(H(2)P(2)O(7))(0.5), which forms at 375 degrees C has been characterized. The unit cell is monoclinic with lattice parameters a = 16.271(3) Å, b = 6.319(1) Å, c = 5.122(1) Å, beta = 90.59(2) degrees, and Z = 4.

Journal Article↗
PubMed2005

One-pot synthesis of metalated pyridines from two acetylenes, a nitrile, and a titanium(II) alkoxide.

Four-component coupling process involving two acetylenes, a nitrile, and a divalent titanium alkoxide reagent, Ti(O-i-Pr)(4)/2i-PrMgCl, directly yielded titanated pyridines in a highly selective manner. The reaction can be classified into four categories: (i) a combination of an internal acetylene, a terminal acetylene, sulfonylnitrile, and the titanium reagent to yield alpha-titanated pyridines, (ii) a combination of an internal acetylene, a (sulfonylamino)acetylene, a nitrile, and the titanium reagent to yield alternative alpha-titanated pyridines, (iii) a combination of an internal acetylene, a (sulfonylamino)acetylene, a nitrile, and the titanium reagent to yield titanated aminopyridines, and (iv) a combination of an acetylenic amide, a terminal acetylene, a nitrile, and the titanium reagent to yield pyridineamides with their side chain titanated. Some of these reactions enabled virtually completely regioselective coupling of two different, unsymmetrical acetylenes and a nitrile to form a single pyridine. Synthetic applications of these reactions have been illustrated in the preparation of optically active pyridines and medicinally useful compounds.

Journal Article↗
PubMed2000

Effect of casting method on castability of titanium and dental alloys.

Titanium, once considered to be difficult to cast because of its relatively high melting point (1670 +/- 50 degrees C) and strong chemical affinity, can now be acceptably cast using newly developed casting apparatus. The objectives of this study were to examine the castability of commercially pure (CP) titanium using an ultra high-speed centrifugal casting machine and a pressure difference-type casting unit and to compare the castability of titanium with that of conventional dental casting alloys. To determine castability, two types of patterns were used: a mesh pattern of 22 x 24 mm cut polyether thread sieve, and a saucer pattern (24 mm diameter) perforated to create four T-shaped ends. The casting equipment significantly affected the mold filling of both patterns (p < 0.001). The castability indices obtained from both patterns of CP titanium cast in the centrifugal casting machine were significantly (p < 0.05) better than the indices of the castings produced in the pressure-difference casting unit. The radiographs of the saucer pattern cast in the centrifugal casting machine showed some pores that were fewer and smaller in size than the pores found in castings made in the pressure-difference unit. When the ultra high-speed centrifugal casting machine was used with the manufacturer's recommended mold material, the castability of titanium was similar to that of gold alloy or Ni-Cr alloy cast by conventional means.

Journal Article↗
PubMed1999

Thin films of calcium phosphate and titanium dioxide by a sol-gel route: a new method for coating medical implants.

Titanium is a commonly used biomaterial for dental and orthopaedic applications. To increase its ability to bond with bone, some attempts were made to coat its surface with calcium phosphate (CaP). This paper describes a new type of coating. Instead of a pure CaP layer, a mixing of titanium dioxide (TIO2) and CaP is fabricated and deposited as a coating. These layers are deposited by a sol-gel route on pure titanium substrates using various pre-treatments. The method consists of mixing a solution of tetrabutyl ortho-titanate or a sol of titanium dioxide with a solution of calcium nitrate and phosphorous esters. This composite is deposited on to commercially pure titanium plates, mechanically polished or blasted with pure crystalline aluminum oxide, using the spin-coating technique. These coatings are then fired at 650 or 850 degrees C for various times. The samples are characterized by X-ray diffraction for their crystallinity, X-ray photoelectron spectroscopy for their surface chemical composition and scanning electron microscopy for their topography. Samples treated at 850 degrees C present a well-pronounced crystallinity, and a high chemical purity at the surface. The topography is strongly related to the viscosity of the precursor and the substrate pre-treatment. Possibilities to structure the outermost layer are presented.

Journal Article↗
PubMedDate not supplied

A new titanium fiber mesh-cuffed peritoneal dialysis catheter: an experimental animal study.

CAPD catheters are associated with infectious complications. To solve this problem, we developed a new catheter. In our design, sintered titanium fiber mesh material replaced the Dacron cuffs, as used in standard Tenckhoff catheters. The purpose of the current study was to compare the tissue response to new titanium-cuffed vs. Dacron-cuffed catheters. Experimental and standard Tenckhoff catheters were inserted intraperiotoneally in 12 goats, using a so-called two-stage surgical technique. In the first surgical session, the catheters were implanted. However, the percutaneous part of the catheter was buried subcutaneous. After 3-5 weeks, the percutaneous part of the catheter was exteriorized. After 14 weeks of implantation, all implants with surrounding tissue were retrieved and prepared for histological evaluation. Subsequently, we quantified: the characteristics of the fibrous tissue capsule surrounding the cuffs, the tissue inside the cuff porosity, and the epidermal downgrowth. Histologic and histomorphometric evaluation showed that titanium mesh evoked a lesser inflammatory response inside the cuff porosity compared with Dacron cuffs. Besides, the fibrous tissue capsule surrounding the titanium cuffs was significantly thinner. Supported by the obtained results, we conclude that the use of titanium fiber mesh has a great potential for application in percutaneous devices.

Journal Article↗
PubMed2003

Adhesion of bone cells to ion-implanted titanium.

The use of ion-implantation to encourage osseointegration has been investigated using an in vitro model cell culture system and surface analysis. Polished titanium discs were implanted with calcium, potassium and argon ions. The adhesion of bone-derived cells was measured using radioactively labeled cells and the morphology examined using scanning electron microscopy. Similar numbers of cells were found to adhere to the potassium and argon-implanted titanium as to control (non-implanted) titanium. However, adhesion to the calcium-implanted titanium discs was significantly reduced. Moreover, although the cells were found to be well spread on the calcium and potassium-implanted titanium, a much greater proportion of cells appeared to remain rounded and poorly attached on the argon-implanted surface. These differences are discussed in relation to the observed surface roughness and chemistry, which were assessed using interferometry and X-ray photoelectron spectroscopy, respectively.

Journal Article↗
PubMedDate not supplied

Analysis of periprosthetic tissue formation around a porous titanium endoprosthesis using CT-based spatial reconstruction.

OBJECTIVE: Reformatted CT-based image data may be of use in evaluation of new bone formation around massive bone replacement implants, but the impact of metal-induced artifacts on the accuracy of image reconstruction is unknown. This study was designed to evaluate the accuracy and precision of quantitative image reconstruction in the presence of a titanium implant. MATERIALS AND METHODS: Model porous-coated titanium implants were harvested from 23 dogs 12 weeks after surgical implantation. Contiguous 1.5 mm transverse CT scans were done first with the titanium implant in place, then repeated after replacement of the implant with an acrylic spacer. Microradiographs of sections cut at defined locations were used to establish gray level thresholds for image reconstruction and to validate the accuracy of CT-based image data. Reformatted image data were used to determine periprosthetic bone volume (mm3) and area of interfacial contact between bone and implant (mm2). RESULTS: The CT-based data derived with either implant material had an accuracy of 83-88% and a precision coefficient of variation (CV) of 2-4% for both volume and contact area variables. Presence of titanium did not seriously affect the quality of images obtained, and results were strongly correlated with those obtained with acrylic. CONCLUSION: Accurate volumetric data derived from CT-based images of periprosthetic new bone formation can be obtained in the presence of a titanium endoprosthesis. Improved demonstration of spatial relationships of bone and implant may improve postoperative evaluation.

Animals↗
PubMed2005

Stapedectomy outcomes: titanium versus teflon wire prosthesis.

OBJECTIVE: To compare the effectiveness of two stapes prostheses in hearing improvement of patients undergoing stapes surgery for otosclerosis. STUDY DESIGN: Retrospective chart review. METHODS: Titanium and Teflon wire stapes prostheses were compared with regard to effectiveness in closing the air-bone gap. The charts of 461 stapedectomies performed by one surgeon from 1996 to 2001 were reviewed. Patients who underwent stapedectomy for reasons other than otosclerosis, revision cases, and those with inadequate preoperative or postoperative bone-conduction threshold data were excluded. Small fenestra technique using either laser or drill was used for all patients. Inclusion criteria were met by 218 patients. Patients were then grouped according to type of prosthesis used, and hearing outcomes were compared. Measured outcomes were four frequency air-bone gap closure, pure-tone threshold, and rate of sensorineural hearing loss (SNHL). RESULTS: The study group was comprised of 35 titanium and 183 Teflon wire prostheses. Closure of the air-bone gap to less than 10 dB was achieved in 86% of the patients with Teflon prosthesis compared with 71% of those with titanium prostheses. The groups were equivalent in regard to site of otosclerotic disease as well as technique, laser or drill, used to create the fenestra. Rate of SNHL was low for both groups and not significantly different. CONCLUSIONS: Both prostheses provided comparable results, although the Teflon platinum wire prosthesis was slightly superior. The smaller numbers in the titanium group may confound these results. The design of the titanium prosthesis provides a crimp that is circumferential around the incus, and that prosthesis was selected in cases with a narrow incus. The selection bias may also influence the results seen in this study.

Adolescent↗