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PubMed1991

[Is titanium an alternative for base metal alloys?].

Because of the excellent biocompatibility titanium can be considered as an ideal material for prosthetic reconstructions. Especially for base metal alloys titanium is an alternative due to the low cost. Processing still causes problems. In this paper a vacuum pressure casting system and a combination of milling and spark erosion are described and investigated. Both techniques are suitable to manufacture prosthetic restorations with a high accuracy of fit. Problems in dental castings lie in the occurrence of a superficial reaction zone of about 40-100 microns width. No final conclusions concerning the metal-ceramic compound can be drawn at the moment for lack of undisputable results in different mechanical bonding tests. Due to the remaining difficulties the future importance of titanium in prosthetic dentistry cannot be prognosticated.

Dental Alloys↗
PubMed1991

[Ceramo-metallic bond of cast titanium].

The ceramo-metallic bond strength of cast titanium was tested according to DIN draft 13927. While the specimens failed in the bending tests, they clearly passed the 3-point bending test after removal of the surface reaction layer prior to firing. Light microscopy and SEM showed a satisfactory wetting of the titanium surface by the ceramic material. The result of X-ray analyses suggest that titanium particles are retained in the ceramic material when this layer is broken off its metallic substructure.

Dental Bonding↗
PubMed1991

Histomorphometric studies of hydroxylapatite-coated and uncoated CP titanium threaded implants in bone.

Threaded hydroxylapatite-coated implants of commercially pure (CP) titanium were inserted in the rabbit tibial metaphysis. Uncoated CP titanium screw implants inserted in the contralateral leg served as controls. After 6 weeks and 1 year postinsertion, the semiloaded implants were histomorphometrically analyzed. While not significant, there was more direct bony contact with the hydroxylapatite-coated implants after 6 weeks of follow-up. One year after insertion, there was significantly more direct bone-to-implant contact with the uncoated CP titanium controls.

Animals↗
PubMed1991

A removal torque and histomorphometric study of bone tissue reactions to commercially pure titanium and Vitallium implants.

Screw-shaped commercially pure (CP) titanium and Vitallium implants were inserted in the rabbit tibial metaphysis. After a healing period of 3 months, it was demonstrated that a higher torque was needed to remove the CP titanium implants (average 24.9 Ncm) compared to Vitallium implants (average 11.7 Ncm). The histomorphometric part of the study revealed more bone-to-metal contact for the CP titanium implants (average 34.7%) compared to the Vitallium implants (average 21.7%). The results obtained in this study could be explained by differences in the topography or in biocompatibility of the metals, or a combination of these two factors.

Animals↗
PubMed1991

Release and excretion of metal in patients who have a total hip-replacement component made of titanium-base alloy.

Serum concentration and urinary excretion of titanium, aluminum, and vanadium were measured for patients who had a well functioning cementless primary total hip replacement of one of two different designs, for patients who had a loose total hip replacement that was to be revised, and for control subjects who had no implant. Serum concentrations of titanium were elevated approximately twofold in the patients who had a loose implant, compared with the values for the control subjects. No major differences in terms of urine concentration of titanium, serum concentration of aluminum, or urine concentration of aluminum were observed among any of the groups that were studied. Concentrations of vanadium were uniformly low in all groups.

Adult↗
PubMed1990

[Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].

Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated.

Carbon↗
PubMed1990

[Grinding of titanium. 2. Commercial vitrified wheels made of alumina abrasives].

Cast titanium was ground with commercial vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.

Aluminum Oxide↗
PubMed1990

[Study of pure titanium electrolytic polishing].

This study attempted to polish pure titanium test pieces electrolytically to mirror surface at the size of cast denture frames. Electrolytic polishing of pure titanium could be done on an area of 30 cm2 with a non-aqueous electrolyte. Small pure titanium plates could be polished electrolytically, but a uniformly smooth surface could not be obtained easily with large testpiece. The optimal electrolytic conditions were 30 V for 6 min at 25 degrees C using a solution consisting of 70 ml ethyl alcohol, 30 ml iso-propyl alcohol, 6 g aluminum chloride, and 25 g zinc chloride. The solution was safe and had less restriction of frequency of use.

1-Propanol↗
PubMed1990

[Casting accuracy and shrinkage of titanium castings made with zirconia investments].

To obtain inlay, crown and bridge types of titanium castings with sufficient size accuracy, zirconia investments with 10 mol % calcia were studied for their setting expansion, thermal expansion, total expansion, casting shrinkage compensation deficiency on fabrication method, particle size of zirconia, calcia and mixing liquid. Addition of calcia caused the change from contraction to expansion in setting and the additional thermal expansion at 900-1,200 degrees C. The choice of calcia and mixing liquid makes great influence on setting expansion, which is grouped into saturation type and delayed expansion type. By the use of the saturation type, total expansion could be controlled in the range of -2-(+)3%. Titanium castings of inlay, crown, bridge types with the values -2-(+)2% of casting shrinkage compensation deficiency could be successfully obtained. The casting shrinkage of titanium was estimated as 1.8-2%. The castings have the surface with a metallic brilliance as cast.

Calcium↗
PubMed1989

[Polishing of titanium prosthetics (Part 6). The chemical polishing baths containing hydrofluoric acid and nitric acid].

Titanium was polished using several chemical polishing baths containing different ratios of hydrofluoric acid and nitric acid. The meltage, surface roughness, and surface texture of titanium samples after chemical polishing were affected by the ratio of hydrofluoric acid and nitric acid. Generally the meltage increased and surface roughness decreased when the mole concentration of hydrofluoric acid was high and that of nitric acid was low. For example the chemical polishing bath containing 5 mole hydrofluoric acid and 5 mole nitric acid improved the surface texture in one minute, but SEM observation revealed a partially rough surface caused by the excessive solution. The chemical polishing bath containing 1 mole hydrofluoric acid and 5 mole nitric acid did not improve the surface texture in a short time because of low solubility, but improved the surface texture gradually with the extension of the immersion time and a good surface texture was observed by SEM. The chemical polishing using the chemical polishing bath with low solubility and immersion of the prosthetics for a rather long time were considered useful procedures to obtain a smooth surface of titanium prosthetics while maintaining their accuracy.

Dental Polishing↗
PubMed1989

[Dental application of superplastic forming for titanium complete denture bases].

In order to investigate the application of superplastic in forming dental prosthesis, the sheets of titanium and its alloy were deformed to the complete denture bases by using a trial hot press and ceramic die. The results are summarized as follows: 1) By the hot press. It was possible to deform the sheet at a deformation speed ranging from 1 x 10(-3) to 3 x 10(-2) mm/sec at a temperature up to 900 degrees C under a vacuum down to 10(-3) Torr. 2) The trial ceramic die was prepared by sintering the green of the CaO-TiO2-ZrO2-MgCl2 system at 1150 degrees C for 6 hours in the atmosphere. The compressive strength, the thermal expansion, and the surface roughness of the test piece of the die were 11 kg/cm2, 0.8%, Ra = 1.4 microns and Rz = 6.8 microns, respectively. 3) Both the sheet of pure chemical titanium and commercial superplastic titanium alloy Ti-6Al-4V were deformed under the conditions of about 0.1 mm/min, 850 degrees C, and 10(-3) Torr. The deformed surface of the complete denture bases appeared to be nearly the same metallic color of each raw sheet and the pattern was the same as the detail of the die. The oxygen enriched layer of the article determined by EPMA was far thinner than that of a dental cast.

Dental Alloys↗
PubMed1989

[High temperature reactivity between titanium and refractory oxides in dental casting procedure. Fundamental study on refractoriness of investments and ceramo-metal bonding by analytical SEM and oxide single crystals].

The reactivity of various refractory oxides (SiO2, Al2O3, MgO, CaO, ZrO2) with molten titanium was investigated by energy dispersive X-ray spectroscopy (EDS), using single crystals of oxide as specimen. The region of the reaction boundary between titanium and single crystal oxide was observed by electron microscopy (SEM). Elemental analysis across the Ti/oxide boundary was done by EDS and the reaction layer thickness was quantitatively determined. Of these refractory oxides, SiO2 is the most reactive with titanium followed by Al2O3. The 250 microns thick Si-rich region and 100 microns thick Al-rich region were formed respectively in Ti around the remnant oxides. The diffusion of Si as a result of reaction is greater than that of Al. MgO, CaO, ZrO2 show very little reaction with Ti and the reaction layer thickness was below the spatial resolution of EDS (approximately 1 micron). The thickness and composition of the reaction layer and reactivity were determined. These results were in good agreement with those obtained by ESCA.

Chemical Phenomena↗
PubMed1989

The retention of titanium pins in high-copper amalgam and their influence on its fracture resistance.

The influence of titanium pins on the fracture resistance of amalgam and the retention of amalgam by titanium pins were compared to that of stainless-steel pins. The retention of stainless-steel pins embedded in amalgam to various depths was also evaluated. None of the pins had a significant influence on the compressive fracture resistance of amalgam. All pins embedded to standard depth in amalgam failed in tension, with titanium pins demonstrating the lowest resistance to tensile forces. Stainless-steel pins embedded 1.75 or 1.5 mm and loaded in tension caused failure in the amalgam, but at forces comparable to the retention of such pins in dentin.

Copper↗
PubMed1989

[Material testing for the use of titanium in bonded prosthodontic restorations].

The effects of chemically etching cast pure titanium to achieve a microretentive surface morphology were studied by SEM. Etching failed to produce an effective improvement of the retentive structures compared to air brushing with Al2 O3 of 50 microns grain size. The bond strength values of the Silicoater-treated retentive surfaces of titanium and Wiron 88 (bonding agent Comspan) determined by shear tests were considerably higher than those of the air-brushed or chemically etched surfaces (bonding agents Comspan, ABC-Zement, Superbond). The clinical use of the Silicoater procedure in bonded restorations seems to provide a suitable retentive mechanism for titanium frameworks.

Acid Etching, Dental↗
PubMed1989

[Titanium in adhesive bridge technic: adhesive-metal-bond].

The application of titanium as bridge and crown metal suggests itself because of its suitable mechanical qualities and its stability against corrosion. The frequent use in medicine proofs its excellent biocompatibility. Because of the problematical casting requirements titanium has not been used very often in dentistry. As these problems had been solved recently, the question is whether titanium is suitable as resin- bonded bridge material. We compare different surface conditioning systems such as silicoating, tin plating and corrosion. The investigation shows that these surface pretreatments give stable bond strengthes.

Corrosion↗
PubMed1980

[Internal fixation for fractures of the lateral malleolus with titanium "crown"-plates (author's transl)].

This team of authors constructed a so called "crown"-plate from titanium, suitable for fixation of lateral malleolar fractures. The plate seems to be ideal for Weber-B type fractures, which are level with the joint space, and it can be applied in the more distal (Weber-A) and proximal (Weber-C) fractures too. The titanium plate was used in 166 fractures with good results. On the basis of the follow up assessment of 151 healed cases the authors feel encouraged to suggest the use of the titanium crown plate for internal fixation of lateral malleolar fractures.

Ankle Injuries↗
PubMed1981

Osseointegrated titanium implants in the temporal bone. A clinical study on bone-anchored hearing aids.

The purpose of this study is to investigate the possibilities for attaching a new type of direct bone conduction hearing aid. Using a gentle surgical technique, titanium screws were inserted into the temporal bone of fourteen patients suffering from hearing impairment. The implants became integrated with the living bone tissue and have remained so for a follow-up period of, at present, two to four years. It is therefore concluded that titanium implants may be osseointegrated in the temporal bone in a similar manner to that previously described for long bones. The bone-anchored titanium screws were connected to a permanently skin-penetrating abutment, which in turn was used for attachment to a hearing aid. In this way a direct bone conduction without obstructing soft tissue layers is secured. The permanent skin penetration caused no adverse soft tissue effects. The new system has improved pure-tone hearing threshold by about 15 dB. Further research is aimed at the construction of a new hearing aid that is better adapted to the impedance situation existing in the directly bone-anchored cases.

Adolescent↗
PubMed1995

Biology of grit-blasted titanium alloy implants.

This study describes the biologic integration of grit-blasted titanium alloy (Ti-6A1-4V) implants that were press fit into the distal femoral canal of young adult rabbits and evaluated by histologic, histomorphometric, and biomechanical methods. Polished and aluminum oxide grit-blasted (4.2 +/- 0.7 microns surface roughness) solid implants were compared with titanium fibermetal implants. Nondecalcified cross sections were studied by histology, histomorphometry, and electron microscopy in the backscatter mode at 3, 6, and 12 weeks after implantation. Pullout strength was measured at 12 weeks. Data were analyzed by analysis of variance and post-hoc Student-Newman-Keuls and Scheffe's tests. The blasted implants had significantly more bone intimately in contact with the implant surface (31%) than the fibermetal (17%), or solid polished implants (15%). By 3 weeks, woven bone had formed directly on the surface of the blasted implants, whereas there was a discrete space between woven bone and the other implants. Active remodeling of bone was shown by fluorochrome uptake at the surface of the blasted implants at 12 weeks after implantation. The strength of fixation of blasted and fiber-metal implants was significantly greater than polished implants at 12 weeks after implantation. Direct attachment of newly formed bone onto the blasted implant surface was confirmed by backscatter electron microscopy. The results of this study indicate that grit-blasted titanium surfaces provide an excellent surface for bone implant integration.

Alloys↗