KETORI Tatsuo TOHOKU UNIVERSITY,School of Dentistry. Assistant, 歯学部, 助手 (50234646)
KASAHARA Shin TOHOKU UNIVERSITY,Dental Hospital. Lecturer, 歯学部・付属病院, 講師 (70169407)
YODA Masanobu TOHOKU UNIVERSITY,School of Dentistry. Assistant Professor, 歯学部, 助教授 (70005073)
NAKAYAMA Takafumi The Research Institute for Electric and Magnetic Material. Chief research worker, 研究部, 主任研究員 (40164363)
OKUNO Osamu TOHOKU UNIVERSITY,School of Dentistry. Professor, 歯学部, 教授 (50014080)
|Budget Amount *help
¥7,400,000 (Direct Cost : ¥7,400,000)
Fiscal Year 1997 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1996 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1995 : ¥4,900,000 (Direct Cost : ¥4,900,000)
We have designed and studied new removable crowns and bridges. The crowns and bridges are separately prepared by dental casting with Fe-Pt-Nb magnetic alloys for outer caps and magnetic stainless steel for inner caps, respectively, so that magnetic force reinforce their physical strengh. The purpose of this study was to examine the applicability of Fe-Pt-Nb magnetic alloys to outer caps by dental casting. The first experimentation was to investigate effects of differences in titanium investments and the mold temperature on Fe-Pt-Nb magnetic alloys. The second experimentation was to investigate effects of additive elements such as Si and Nb on Fe-Pt-Nb magnetic alloys. The last experimentation was to investigate effects of magnetizing nethods on attractive forces in Fe-Pt-Nb magnetic alloys. The results were as follows :
1.Measuring surface foughness and magnetic properties, titanium investment (Titavest CB) and the mold Temperature (200-600ﾟC) were optimum condition for dental casting o
f Fe-Pt-Nb magnetic alloys.
2.The addition of Si 0.1 (mole%) over improved the surface roughness and decreased the casting defect, and the addition of Si 0.2 (mole%) below and of Nb 0.5 (mole%) over could produce the excellent magnetic properties. Therefore, it was conducted that the optimal composhition was Fe-39.5Pt-0.65Nb-0.1Si (mole%).
3.The attractive force which was observed with crown-type (magnetized along the crown axis, Fe-39.5Pt-0.65Nb-0.1Si (mole%)) showed 536gf on the average. This value is enough to retain removable crowns and brides for dental use.
Further study is needed to elucidate the relationship between the adaptation accuracy and the attractive force as well as mechanical properties of these alloys.