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PubMed2003

Titanium cage reconstruction after cervical corpectomy.

OBJECT: The authors evaluated the efficacy of titanium cage- and anterior cervical plate (ACP)-augmented fusion for reconstruction following decompressive cervical corpectomy in nontraumatic disease. METHODS: Forty-five patients ranging from 37 to 77 years of age underwent anterior cervical corpectomy followed by titanium cage-assisted reconstruction in which the cages were filled with autologous bone obtained from the resected vertebral bodies (VBs). Plates were placed in all patients. Follow-up radiographic evaluation included computerized tomography scanning and plain flexion-extension radiography. Fusion was demonstrated in all but one patient without reconstruction-related complications. The single complication involved an endplate VB fracture with pistoning of the cage into the VB. The mean follow-up period was 12.9 months. CONCLUSIONS: Autologous corpectomy bone-filled titanium cages supplemented with ACPs are an effective means of reconstruction after compressive cervical corpectomy. This technique provides a reasonable alternative to procedures involving long solid strut grafts obtained from the bone bank or from the patient.

Adult↗
PubMed2004

Three-level and four-level anterior cervical discectomies and titanium cage-augmented fusion with and without plate fixation.

OBJECT: Cage-assisted anterior cervical discectomy and fusion (ACDF) has proven to be a safe and effective procedure for the treatment of one- and two-level degenerative disc disease (DDD). To the authors' knowledge, clinical results after three- and four-level interbody cage-augmented ACDF have not been reported in the literature. The authors investigated the safety and effectiveness of titanium cages used in such procedures and evaluated the results in cases with or without plate fixation. METHODS: Fifty-six patients suffering from cervical DDD were divided into two groups. Group 1 included 32 patients who underwent titanium cage-assisted ACDF; Group 2 included 24 patients who underwent the same procedure, supplemented with plate fixation. The cervical DDD was confirmed by radiography and magnetic resonance imaging. The patients underwent radiographic evaluation to assess cervical lordosis, segmental height of cervical spine, the height of the foramina, and spinal stability. Neurological outcomes were assessed using the Japanese Orthopaedic Association (JOA) scores. Neck pain was graded using a 10-point visual analog scale (VAS). The follow-up period ranged from 13 to 28 months (mean 17.2 months). In both Groups 1 and 2 significant increase (p < 0.001) was demonstrated in the JOA scores (preoperatively 10.7 +/- 2.4 and 11.1 +/- 2, postoperatively 13.9 +/- 2.2 and 14.1 +/- 2.3, respectively) and VAS pain scores (preoperatively 8.8 +/- 0.9 and 8.5 +/- 1, postoperatively 3.1 +/- 2.1 and 2.8 +/- 1.8, respectively); however, there was no significant intergroup difference. A significant increase in the cervical lordosis, foraminal height, and segmental height was observed in both groups. Good stability of cage fusion was obtained in both groups 12 months postoperatively (90.6% in Group 1 and 91.7% in Group 2); however, there were no statistically significant intergroup differences. The complication rate in Group 2 was higher than that in Group 1. The hospital length of stay in Group 1 was significantly lower than in Group 2 (p < 0.001). CONCLUSIONS: Analysis of these findings demonstrated that titanium cage-assisted ACDF provided long-term stabilization, increased lordosis, increased segmental height, and increased foraminal height. In both groups good neurological outcomes were achieved and donor site morbidity was avoided. The lower complication rate and shorter hospital stay, however, make the cage-assisted fusion without plate fixation better than with plate fixation.

Adult↗
PubMed1996

Uncemented total knee arthroplasty: report of 109 titanium knees with cancellous-structured porous coating.

One hundred twenty-three uncemented total knee arthroplasties were performed between November 1986 and November 1989. The implants were pure titanium with porous coating for bony ingrowth. One hundred nine of these knees were followed for 2 to 5 years (average: 31.5 months). Clinical evaluation of the results, using the Hospital for Special Surgery Knee Rating Scale, revealed an increase in the average knee score from 62.9 preoperatively to 92.5 postoperatively, with excellent or good results in 94.5% of the cases. Thirteen knees (12%) had 26 radiolucent lines or areas. There was no complete lucency underneath any implant, and no knees were revised for loosening. One knee required replacement of the tibial insert for instability. While titanium implants were successful in achieving secure fixation and high knee scores in the short term, longer follow up will be necessary for more definitive conclusions, especially in regard to the potential problems with titanium wear debris.

Adult↗
PubMed2001

Magnetic resonance imaging of periarticular titanium screws.

Magnetic resonance imaging (MRI) may be the most sensitive modality for detecting post-traumatic degeneration of articular cartilage. Magnetic resonance imaging must accurately depict articular cartilage in the presence of periarticular fracture stabilization devices to be effective for postoperative imaging of articular fractures. This study examines how close titanium screws can be inserted to tibial articular surfaces and still allow accurate MRI of the overlying articular cartilage. Cannulated titanium screws were inserted at varying distances from subchondral bone in the proximal and distal tibiae of embalmed human cadaveric legs, which were then imaged using a standard nonfat-saturated fast low angle shot two-dimensional sequence (FLASH 2D). The distance from the center of the screw to the subchondral bone and the thickness of the articular cartilage directly overlying the screw was then determined by direct measurement and by measurement on the scanned images. To allow FLASH 2D MRI of the articular cartilage, 7.3-mm screws had to be at least 13 mm from the subchondral bone, and 4.5-mm screws had to be at least 12 mm from the subchondral bone. For MRI to be effective for the postoperative imaging of the articular surface following severe articular fractures of the tibia, titanium fracture hardware must be farther away from the articular surface than these minimum distances. Alternate materials for stabilizing articular fractures are available and may allow clearer and more accurate imaging of the articular cartilage when inserted close to the articular surface.

Bone Screws↗
PubMed2000

Application of a centrifugal shooting type polishing system to polish pure titanium.

Titanium is a difficult metal to grind, and thus mechanical polishing using conventional rotating tools takes a lot of time. The purpose of this study was to examine the polishing effect of a centrifugal shooting type polishing system on a pure titanium surface processed with a CAD/CAM system. The specimens' surfaces were polished for various times using this apparatus, then the center line average roughness (Ra) of each specimen was measured with surface roughness measuring apparatus. In addition, the surfaces after polishing were observed with a scanning electron microscope. After 50 sec of polishing, Ra decreased from 1.1 microns to less than 0.6 micron, and after 60 sec of polishing the cutting marks generated by the CAD/CAM system disappeared and a smooth surface was observed. Therefore, it appears that a centrifugal shooting type polishing system is effective at polishing pure titanium.

Computer-Aided Design↗
PubMed2001

Corrosion behavior of dental alloys coupled with titanium. Part 2. The area ratio dependence in five solutions.

Sixteen alloys and five pure metals were used and the open circuit potentials (OCP) and the coupled potentials with titanium were measured in five kinds of solutions. All alloys and metals showed the maximum OCP in 1.3% lactic acid solution, and the minimum in 0.01% sodium sulfide solution. The coupled potential depended on the area ratio (alloy/titanium). This dependence was different in every solution. From the area ratio dependence of the coupled potential, the potassium fluoride solution was thought to be active with pure titanium. In contrast, sodium sulfide solution was thought to be active with the alloys and the metals. The effect of the co-existence of pure titanium was very small in the sodium sulfide solution.

Corrosion↗
PubMed2002

Study of resin-bonded calcia investment: part 2. Effect of titanium content on the dimensional change of the investment.

In the present study, titanium powder was chosen as an expanding agent of an experimentally prepared resin-bonded calcia investment. The effect of Ti content on the dimensional change was investigated. In addition, the effects of the heating rate and heating temperature on the dimensional change of the investment were investigated during setting and after heating. The expansion increased with Ti content and the highest expansion (1.57%+/-0.58) was obtained at 10 mass% Ti. The highest expansion was obtained at 900 degrees C for 30 min heating and was independent of the heating rate. These findings mean that the titanium powder in the calcia investment oxidized sufficiently at that heating condition. It was found that the developed resin-bonded calcia investment was able to compensate for casting shrinkage of pure titanium by adding some Ti powder to the investment.

Algorithms↗
PubMed2002

Calcium-ion incorporation into titanium surfaces accompanied by electrochemical apatite-deposition.

The depths of calcium-ion incorporation into a commercially pure titanium and an experimental beta-type titanium alloy were determined using Auger electron spectroscopy. After the electrochemical deposition of apatite, new compositional gradients appeared in the profiles in which the Ca and P concentrations gradually decreased as a function of the depth up to 6-8 nm. The relative concentration of Ca in the outermost layer was higher than that of P. On the other hand, after the soaking in a simulated body fluid, the relative concentration of P was higher than that of Ca in the outermost layer. These results suggested that Ca ions were well incorporated into the outermost oxide layer of titanium accompanied by the electrochemical apatite-deposition on its surface.

Apatites↗
PubMed2004

Thermal expansion typed investments for casting titanium.

New investments for titanium were developed by adding ZrC and ZrN as additives for thermal expansion to an MgO cement base investment with setting shrinkage and low thermal expansion. Setting, thermal and residual expansion, X-ray diffraction and compressive strength of these experimental investments, surface roughness of the cast plate and casting accuracy of titanium crowns were evaluated. Thermal expansion of investments increased with additive amounts, and residual expansion occurred even when cooling to room temperature after firing in an air atmosphere by the oxidation to ZrO2 of these additives. The casting accuracy of full-crowns cast into molds at room temperature correlated with the content of ZrC and ZrN. As the result the cast titanium crown could be obtained with low surface roughness and good adaptability.

Analysis of Variance↗
PubMed2004

Durability of tungsten carbide burs for the fabrication of titanium crowns using dental CAD/CAM.

The purpose of this study was to evaluate the durability of tungsten carbide burs for the fabrication of titanium crowns using two dental CAD/CAM systems (DECSY, Digital Process, Japan and Cadim, Advance, Japan). A tungsten carbide bur in each system was examined and used without fracture to fabricate 51 titanium crowns. For both systems tiny chips were found on the bur blade at the 11th machining. These chips gradually enlarged as the number of machining times increased. At the first machining no significant difference in the average surface roughness was found on the crown between the two systems (1.6 microm for DECSY and 1.2 microm for Cadim). The cutting grooves became dull and the average surface roughness increased as the number of machining times increased. It is concluded that the tungsten carbide burs for both systems can be used to fabricate up to 51 titanium crowns.

Computer-Aided Design↗
PubMed2004

Phosphate-bonded ZrSiO4 investments added with ZrC and ZrN for casting titanium.

In this study, new investments for titanium were developed by adding ZrC or ZrN as chemical additive for thermal expansion to a phosphate-bonded zircon (ZrSiO4) investment. The following effects were then examined: setting expansion, residual thermal expansion, and compressive strength of these experimental investments; surface roughness of cast plate; and casting accuracy of titanium crown. For residual thermal expansion, it occurred even while investments were cooled to room temperature after firing in air atmosphere. This was due to the additives' oxidation to ZrO2--suggesting that residual thermal expansion increased with increased amount of these additives. As for casting accuracy of full-crown cast into molds at room temperature, it correlated with the ZrN content. Hence by adding the right amount of ZrN, cast titanium crowns with low surface roughness and good adaptability could be obtained.

Analysis of Variance↗
PubMed2004

Machinability evaluation of titanium alloys.

In the present study, the machinability of titanium, Ti-6Al-4V, Ti-6A1-7Nb, and free-cutting brass was evaluated using a milling machine. The metals were slotted with square end mills under four cutting conditions. The cutting force and the rotational speed of the spindle were measured. The cutting forces for Ti-6Al-4V and Ti-6Al-7Nb were higher and that for brass was lower than that for titanium. The rotational speed of the spindle was barely affected by cutting. The cross sections of the Ti-6Al-4V and Ti-6Al-7Nb chips were more clearly serrated than those of titanium, which is an indication of difficult-to-cut metals. There was no marked difference in the surface roughness of the cut surfaces among the metals. Cutting force and the appearance of the metal chips were found to be useful as indices of machinability and will aid in the development of new alloys for dental CAD/CAM and the selection of suitable machining conditions.

Alloys↗
PubMed2004

The thickness effects of titanium castings on the surface reaction layer.

In this study, wedge-shaped CP titanium castings and Ti-6Al-7Nb alloy castings were produced by three types of investment. The effects of the castings' thickness on surface reaction layer were investigated by measuring Vickers hardness, observing the microstructure, and analyzing the oxygen concentration. It was found that the thickness of the surface reaction layer was affected by the thickness of the wedge-shaped castings, and that the hardness value near the surface became lower toward the tip of the wedge-shaped CP titanium and Ti-6Al-7Nb alloy castings. The surface reaction layer of the Ti-6Al-7Nb alloy castings was thinner than that of the CP titanium castings.

Dental Alloys↗
PubMed2005

New surface modification of titanium implant with phospho-amino acid.

The purpose of this study was to investigate a new biochemical surface modification technique for titanium implants using phospho-amino acid. Pure titanium disks were pretreated with 10 N HCl and ultrapure water at room temperature for 30 minutes respectively. Then these disks were modified with either L-threonine (Thr) or O-phospho-L-threonine (P-Thr) at 37 degrees C for 12 hours. X-ray photoelectron spectroscopy (XPS) chemically analyzed the modified surfaces. It was revealed that the N 1s peak which originated from Thr was not detected in the wide-scan spectrum of Thr-modified surface, whereas three peaks of N 1s, P 2s, and P 2p which originated from P-Thr were detected in the wide-scan spectrum of P-Thr-modified surface. Moreover, the P 2p peak of P-Thr which reacted with the surface significantly shifted to a lower binding energy (p < 0.05). Based on the results of this study, it was concluded that P-Thr chemically bonded to the titanium surface treated with HCl.

Dental Bonding↗
PubMed2006

Influence of molecular weight of PMMA in PMMA/MMA-TBB resin on durability of adhesion to titanium against thermal stress in water.

The present study examined the effect of the molecular weight of poly(methyl methacrylate) (PMMA) used in PMMA/ MMA-tributylborane (TBB) resin cement on the durability of adhesion to titanium against repeated thermal stress in water. PMMA beads with the same diameter and molecular weights of 1427, 239, 116, 78, and 66 (x 10(3)) were used. Titanium disks bonded to stainless steel or acrylic rods with the PMMA/MMA-TBB resin were subjected to a thermal cycling test (500 and 2,000 cycles) in water followed by tensile testing. Change in molecular weight of the resin cements collected after thermocycling and tensile testing was examined using size exclusion chromatography (SEC). The acrylic specimens exhibited a significant decrease in post-thermocycling bond strength as compared to the stainless steel specimens. It was also found that the molecular weight of PMMA powder in PMMA/MMA-TBB resin had little influence on adhesion durability to titanium. In terms of the molecular weight of resin cements, they decreased and then increased after 500 and 2,000 cycles respectively.

Acrylic Resins↗
PubMed2006

Hydroxyapatite film coating by thermally induced liquid-phase deposition method for titanium implants.

Thermally induced liquid-phase deposition method was employed to produce a thin hydroxyapatite (HA) film on a titanium substrate in a metastable calcium phosphate solution. Titanium foil of 100x10x0.02 mm3 was used as a substrate. Prior to HA coating, the substrate was immersed in 5 M NaOH solution at 60 degrees C for 24 hours. Substrate temperature was kept constant at 60 degrees C for 0.5-3 hours by electrical heating with a DC power source in the metastable calcium phosphate solution. An X-ray diffractogram indicated that the film deposited on the titanium substrate was composed of HA. The amount of HA deposited increased with increase in heating time. These results suggested that a uniform HA film can be formed by simple chemical and thermal treatments. Based on the results of this study, this technique seemed to be useful for producing uniform HA coatings on complex-shaped and porous dental implants.

Coated Materials, Biocompatible↗
PubMedDate not supplied

Laser-welded titanium frameworks supported by implants in the edentulous maxilla: a 2-year prospective multicenter study.

PURPOSE: The aim of this study was to evaluate the clinical and radiographic performance of patients who received implants and fixed prostheses with laser-welded titanium frameworks. MATERIALS AND METHODS: Fifty-eight consecutive patients were treated with 349 osseointegrated implants ad modum Brånemark in the edentulous maxilla at 6 implant centers. The patients were randomly arranged into 2 groups at the time of final impression. Twenty-eight patients received laser-welded titanium frameworks and 30 patients received conventional cast frameworks. Clinical and radiographic data were collected for 2 years in function. RESULTS: The 2 groups of patients showed similar results. The 2-year overall cumulative implant survival rate from the time of implant placement and prosthesis insertion was 93.7% and 96.2%, respectively. The corresponding cumulative survival rate for prostheses was 96.6%. Two patients, 1 from each group, failed completely and resumed using conventional complete dentures. The only obvious factor that could possibly be related to the 2 complete failures was a smoking habit. However, it was not possible to significantly correlate implant failures to smoking habits in this study. No fractures were observed in the frameworks or implant components, and both groups experienced the same frequency of resin veneering material fractures. The overall average marginal bone loss was 0.4 mm (SD 0.8 mm). CONCLUSION: Patients treated with implant-supported prostheses fabricated with laser-welded titanium frameworks in the edentulous maxilla presented comparable results to patients with conventional cast frameworks after 2 years in function.

Adult↗
PubMedDate not supplied

A longitudinal clinical study of Procera ceramic-veneered titanium copings.

PURPOSE: The purpose of the present paper was to study the long-term clinical results with ceramic-veneered Procera titanium copings. MATERIALS AND METHODS: A total of 44 titanium copings (fabricated for 22 patients) veneered with a low-fusing ceramic were followed for 60 to 78 months. The clinical examinations were performed by licensed specialists in prosthetic dentistry. The crowns were rated according to the California Dental Association system. In addition, Bleeding Index and Margin Index were also evaluated. RESULTS: In 3 crowns ceramic fractures necessitated their replacement. Two crowns had to be replaced because of caries. The ratings for surface and color had changed markedly, from excellent to acceptable. Regarding anatomic form, with the exception of the 3 fractured ceramic crowns, there were no obvious changes. The margin integrity, aside from the 2 crowned teeth with caries, was recorded as satisfactory (excellent or acceptable) for all other crowns; in fact, a large majority were rated excellent. Regarding Bleeding Index, there were no differences between crowned teeth and control teeth. Changes in Margin Index showed that the gingiva of the crowned teeth had retracted. CONCLUSION: Of the various clinical factors evaluated, only surface and color-related to the low-fusing ceramic used for veneering-showed any obvious change during the follow-up period. Otherwise the veneered titanium copings had, in general, performed well.

Adult↗