Dentistry – Prosthodontics – Holding or positioning denture in mouth
Patent
1990-01-29
1991-05-07
Wilson, John J.
Dentistry
Prosthodontics
Holding or positioning denture in mouth
A61C 13235
Patent
active
050132431
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a denture attachment utilizing a magnetic attractive force. More particularly, the present invention relates to a denture attachment to be embedded in a denture base, which comprises a magnet body to produce a magnetic attractive force between the magnet body and a soft magnetic alloy coping embedded in the root of a tooth, thereby enabling stable attachment of the denture in an oral cavity.
2. Background Art
In using a denture by removing a damaged crown of a tooth, there has been used a denture such that a coping of a soft magnetic alloy formed with a flat surface along the top portion of the gingiva is fixedly embedded in a top portion of the root of the tooth left in the gingiva, whereas the magnet body is embedded in the denture base at a position corresponding to the coping, to hold the denture base stably on the gingiva by utilizing the magnetic attractive force of the magnet body.
In the case, as shown in FIG. 1, where the crown penetrating through the gingiva 91 is removed to leave the root 92 alone, a coping 93 formed of a soft magnetic alloy and provided with a flat surface at the top thereof is fixedly embedded in the pulp cavity of the root 92. On the other hand, a denture has a denture base 94 formed of a plastic or the like, with a hard denture portion 95 fixed at a position opposed to the coping 93, and a denture attachment 10 is fixedly embedded in the denture base 94 at a position opposed to the coping 93.
For attaching this type of denture utilizing the magnetic attractive force, a denture attachment as shown at numeral 8 in FIG. 2 has hitherto been proposed [Japanese Patent Application Laid-Open (KOKAI) No. 62-231653]. The denture attachment 8, as shown in FIG. 2, comprises a magnet 82 disposed in a stainless steel casing 81 having a projection 83 at an upper portion. As the magnet body 82, a rear-earth permanent magnet based on, for instance, Sm-Co (samarium-cobalt) having a strong magnetic force has been used.
All the conventional magnet bodies, however, have low magnetic attractive forces of about 200 to 300 g. These attractive forces are lower, as compared with the mechanical holding forces of at least 500 g exerted by the springs conventionally used for fastening a denture base to a tooth in an oral cavity.
Besides, the magnet body is liable to be corroded in the oral cavity; therefore, where the rare-earth permanent magnet is exposed in the oral cavity, the magnet body will rust with the result of a rapid lowering in the attractive force and generation of safety problems. Where rust prevention is attempted by covering entirely the magnet body with a casing made of a non-magnetic alloy such as stainless steel, as described in the above-mentioned patent application, the attractive force is lowered due to the presence of the casing made of the non-magnetic alloy between the magnet body and the coping.
Furthermore, there is a proposal for making the rare-earth permanent magnet as a sintered body of powder and protecting the sintered body with a foil of a non-magnetic alloy similarly to the above, but this proposal is impracticable because the foil of the non-magnetic alloy is broken due to the direct contact with the coping.
DISCLOSURE OF THE INVENTION
It is accordingly a primary object of the present invention to provide a denture attachment small in size and having a high attractive force as well as excellent corrosion resistance and wear resistance.
Namely, a denture attachment according to the present invention comprises a magnet body of a rare-earth permanent magnet disposed between a pair of end plates which are arranged perpendicularly to a coping embedded in a root portion of a tooth, a spacer of a non-magnetic alloy disposed beneath the magnet body, and a cap covering these members except the coping side of the end plates and the spacer, with the spacer and the cap being joined to the end plates.
Of each of the pair of end plates, an inner surface opposed to the magnet body is formed as a flat surface, wherea
REFERENCES:
patent: 4431419 (1984-02-01), Portnoy
patent: 4508507 (1985-04-01), Jackson
patent: 4815975 (1989-03-01), Garrel et al.
patent: 4824371 (1989-04-01), Deutsch et al.
patent: 4911640 (1990-03-01), Schwab
Arai Kazuo
Honkura Yoshinobu
Iwama Yoshiro
Tanaka Yoshinobu
Watarai Aki
Aichi Steel Works Limited
Wilson John J.
LandOfFree
Denture attachment does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Denture attachment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Denture attachment will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-936728