Dentistry – Prosthodontics – Holding or positioning denture in mouth
Patent
1996-03-13
1998-08-04
Lucchesi, Nicholas D.
Dentistry
Prosthodontics
Holding or positioning denture in mouth
A61C 13235
Patent
active
057884935
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to denture-supporting permanent magnet attachments which use magnetic attractive force and more particular to denture-supporting permanent magnet attachments which are used as retainers for retaining dentures and which each comprise a supporting plate comprising a magnetic stainless steel glued to the top surface of a coping laid in a tooth root and a permanent magnet assembly laid in a denture base.
BACKGROUND ART
There have already been various attempts to utilize magnetic attractive force interacting between a permanent magnet and a magnetic material alloy in settling a denture within an oral cavity. These attempts are described, for example, by Tomas R. Jackson in "The application of Rare Earth magnetic retention to osseointegrated implants," Int. J. Oral Maxillofac. Implants, Vol. 1, No. 2 (1987), pp. 77-89.
The requirements for putting this kind of dentures to practical use are thought to be that a permanent magnet is completely sealed up in a case made of materials which have been proved to be harmless to the human body and that leak of magnetic flux is small. There has been used, for example, a denture-supporting magnetic attachment having a structure shown in FIG. 3.
FIG. 3 shows a denture-supporting magnetic attachment 30 comprising a permanent magnet assembly 10 and a keeper 20. In FIG. 3, reference numeral 1 denotes a permanent magnet, numeral 2 denotes a case, numeral 13 denotes a seal member. The seal member 13 comprises a seal frame member 14 and a seal center member 15, which are formed into a body by seam welding. Also, the seal member 13 and the case 2 are united in one by seam welding 16.
In this case, the case 2 is formed of (magnetic) ferritic stainless steel, e.g., SUS447J1 to be 4.4 mm in outer diameter, 3.23 mm in inner diameter, 2.1 mm in height and 1.60 mm in depth (0.50 mm in thickness of the bottom and the sides). The case 2 houses a SmCo-system magnet 1, 3.2 mm in outer diameter and 1.4 mm in height. On the other hand, the seal member 13 is formed into one body by seam-welding a seal center member made of (magnetic) ferritic stainless steel such as SUS447J1 and a seal frame member made of (nonmagnetic) austenitic stainless steel such as SUS316L (a). The seal member, which is made 3.2 mm in outer diameter, 2.7 mm in inner diameter and 0.21 mm in thickness, is fit into an open end of the case 2, and then seals up the permanent magnet 1 with seam welding 16.
(Translation Notes: A code with a prefix "SUS" indicates a stainless steel defined in Japanese Industrual Standard (JIS). The steel SUS447J1 contains in weight-%: 28.5-32.0 Cr, 1.5-2.5 Mo and balance iron. SUS316L contains in weight-%: 16-18 Cr, 12-15 Ni, 2-3 Mo and balance iron.)
In FIG. 3, the magnetic flux out of the permanent magnet 1 returns to the magnet via the case 2, the keeper 20 and the seal center member.
FIG. 4 is a partial section showing an exemplary denture-fixing means in which a conventional denture-supporting magnetic attachment is used. In FIG. 4, reference numeral 7 denotes a root member lied in a tooth root 9, which is provided with a keeper 20 formed of magnetic material stainless steel on its top surface and which has a longitudinal section of a substantial T-shape. Reference numeral 8 denotes a denture base, in which the permanent magnet assembly 10 shown in FIG. 3 is placed with its seal member 13 side facing the root member 7. The above described arrangement will produce a magnetic attractive force between the permanent magnet assembly 10 and the root member 7, which causes the denture base 8 to be pressed against the tooth root 9, thereby enabling the artificial teeth 11 to be supported within the oral cavity.
The permanent magnet assembly 10 arranged as described above have been used as follows. As shown in FIG. 5, a denture base and artificial teeth 11 are disposed as a denture in a space where the coronae dentis of natural teeth used to be, and a permanent magnet assembly 10 is embedded in the denture base 10. In case of a molar shown in FIG. 5, t
REFERENCES:
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patent: 5123843 (1992-06-01), Van Der Zel et al.
patent: 5254006 (1993-10-01), Yamada
patent: 5337033 (1994-08-01), Kinouchi et al.
patent: 5421722 (1995-06-01), Stemmann
patent: 5425763 (1995-06-01), Stemmann
Form PCT/ISA/210, (Oct. 24, 1995).
Noguchi Kazumi
Okuno Osamu
Sugihara Toru
Suzuki Hiroya
Tanaka Kiyomi
Hitachi Metals Ltd.
Lucchesi Nicholas D.
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