1997 年 64 巻 4 号 p. 544-556
In the 1950 s, a new method of using magnets for the retainers of removable partial dentures (RPDs) was developed. It utilized magnetic attractive force instead of mechanical friction. However, the magnets used in those days were Alnico, Ferrite and/or Pt-Cobalt magnets and their retentive force was not strong enough to stabilize the dentures. Therefore, they gradually went out of use.
In the middle of the 1970 s, Samarium Cobalt magnets, which have strong magnetic characteristics, were developed and introduced into dental field. In 1976, Sasaki first applied the samarium cobalt magnets to the retainers of PPDs. While in 1981, Mizutani, et al. first used wellfitted ferromagnetic alloy and the magnet for the purpose of stabilizing the RPD. Since then, many researchers have developed devices such as the magnetic retainer and the closed field magnetic attachment placed on the market in 1992. Now, as for the popular retainer of RPD, one can easily use a smaller yet stronger magnetic attachment which uses Neodium rather than Samarium Cobalt magnet.