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Biomedical subjects

O Okuno

Publications and source records attributed to O Okuno.

32 records · Page 2Linked to original sources
PubMed1989

[Application of superplastic titanium alloy for denture base--Part 1. Adaptability of the titanium alloy denture base].

The adaptability of the upper complete denture base made from superplastic alloy 90Ti-6A1-4V was investigated by measuring the space between the master model and the denture base. The denture bases showed a high adaptability with the space less than 0.1 mm, whereas after curing resin for denture, it became worse especially with the heat-curing resin. In addition, the thinnest area of the denture base was observed at the middle of the plate with 38% reduction in thickness, and distortion of the base plate of 0.55mm thickness by curing resin was found to be nearly the same as that of type 304 stainless steel plate of 0.50 mm thickness.

Dental Alloys↗
PubMed1989

[Retention of Pt-Co magnet for dental prosthesis].

Though Pt-Co magnet is inferior to rare-earth magnet in magnetic properties, the magnet is much superior to the corrosional resistances in oral fluids. The purpose of this investigation was to determined the retentive characteristics of Pt-Co magnet. The break away force between the magnet and XM27 stainless steel keeper were measured. The retention of phi 4x 1.5 mm Pt-Co magnet was 49 g. This retention could be increased to 172 g by using stainless steel cup type yoke. These retention were rather small, but if 3 or more couples of attachments or larger Pt-Co magnet attachment were fixed in denture, the retention level approach that of clasp or mechanical precision attachments.

Cobalt↗
PubMed1989

[Sandwich type dental magnetic devices of Nd-Fe-B magnet and permendur].

Nd-Fe-B magnets have a very high maximum energy product (BH max), which is defined as the attractive strength between a magnet and opposing magnetic materials. Permendur (Fe-49 Co-2 V) has the greatest magnetic saturation (Bs), which makes it strongly magnetized. If magnetic retainers were made with Nd-Fe-B magnets and a permendur yoke, they would be small and have strong retention. The purpose of this investigation was to develop small dental magnetic devices with Nd-Fe-B magnets and permendur yokes. The magnetic devices form sandwich-type magnetic circuits with magnetic stainless steel keepers. A 4 x 3 x 2 mm rectangular prism Nd-Fe-B magnet was used. The magnet was sandwitched between the semi-columnar yokes. To protect the magnet from corrosion, the devices were encapsulated with 304 stainless steel by silver brazing and adhesion bonding of a stainless steel tube and foil. The optimum cross-sectional area of the yoke was determined experimentally. The dimensions of the devices were phi 5 x 3.5 mm for 4 x 3 x 2 magnet. The breakaway retention for a keeper of magnetic stainless steel (Type XM 27) was 852 g on average. This breakaway retention is sufficient for dental prosthetic applications.

Beryllium↗
PubMed1989

[Superplastic forming of titanium alloy denture base].

Ti-6Al-4V alloy has both excellent biocompatibility and superior mechanical properties. This Ti-6Al-4V can be deformed greatly and easily at the superplastic temperature of 800 degrees C to 900 degrees C. The superplastic forming of Ti-6Al-4V was made to apply to fabrication of denture base. Almost the same procedure as for dental casting mold was employed in producing the superplastic forming die by the improved phosphate bonded investment. In the pressure vessel of heat resistant alloy, Ti-6Al-4V plate was formed superplastically on the die by argon gas pressure at 850 degrees C. The fit of superplactic forming Ti-6Al-4V denture base was better than that of casting Co-Cr alloy denture bases. The Ti-6Al-4V alloy might react a little with the die. Because micro Vikers hardness of the cross-section did not go up too much near the surfaces. Even just after being formed, the surfaces were much smoother than that of Co-Cr alloy casting. The tensile strength and yield strength of superplastic forming Ti-6Al-4V were higher than those of Co-Cr castings. The elongation was about 10%. These results show that superplastic forming of Ti-6Al-4V would be suitable for a denture base.

Dental Alloys↗
PubMedDate not supplied

Mechanical properties and biomechanical compatibility of porous titanium for dental implants.

Titanium powder with a granule diameter of 420-500 micron was prepared and porous titanium specimens were made from this powder. The mechanical properties of these specimens were examined. The compressive strength and low cyclic compressive fatigue strength were 182 and 40 MPa, respectively. Fractography was also observed by scanning electron microscopy. Typical fatigue characteristics of the bonding areas of the powder were observed. In addition, porous-titanium-coated dental implants with pure titanium cores were prepared. The compressive strength of the material used was 230 MPa, fatigue strength not being improved. Biomechanical stress calculations using the finite element method were made using a model that employed the use of the material implanted in alveolar bone. Shear stress at the implant-bone interface as well as compressive stress concentrations in the bone was calculated. The most suitable elastic modulus for the dental implant was then estimated from these calculations. Finally, based on these results, the use of porous titanium for dental implants was assessed.

Chemical Phenomena↗