FR2718948A1 - Intra-crown magnetic attachment for removable tooth prosthesis - Google Patents

Abstract

The attachment consists of a permanent magnet (6) integrated into an adjoining portion of the prosthesis with the aid of a cage (13) to which it is joined and which slides in a sleeve (14) attached to the prosthesis portion (11) while the latter is being made. An elastic element (7) is placed between the top of the magnet and the end of the sleeve and a ferromagnetic disc (1) is integrated into the adjoining, non-magnetic portion of the prosthesis made from cast metal and has a cap (3) to cover the supporting stump (5).The ferromagnetic disc (1) has a surface coating of a biocompatible metal and the magnet (6) has a surface layer of nickel coated with chrome and an epoxy resin. The ferromagnetic disc is held in a cylindrical cup (2) of a calcinable plastic, while the sleeve, which is also preferably of plastic, has an outer conical wall and a stop (15) to limit the movement of the cage.

Description

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  INTRACORONARY MAGNETIC ATTACHMENT AND METHOD

OF IMPLEMENTATION OF SAID ATTACHMENT

  The invention relates to an intracoronary magnetic attachment for a removable dental prosthesis, of the type comprising: a) a permanent magnet capable of being integrated into the adjoining part of the prosthesis by means of a cage, of which it is integral, which slides in a sheath made integral with said adjoining part during the production of the latter; b) an element, of the elastic type, capable of being placed between the top of said magnet and the bottom of said sheath; c) a ferromagnetic pellet capable of being integrated into the non-magnetic joint part of the prosthesis which is obtained by simultaneous metal casting

  a screed, covering the stump and initially carved with direct wax

  on the master model, and a pivot, initially made of calcified material

  filler, capable of ensuring the permanent connection, by sealing, between said

screed and said stump.

  The attachment in question is mainly described in the request for

  patent FR-9304467 by the same applicants.

  Said attachment has proven in practice to present the main in-

  following: - disordered bimetallization phenomena (between the pellet and the cap)

  and deformation of the ferromagnetic pad (poor contact with the

  mant) due to the fact that it is in the refractory cylinder which is brought to the melting temperature of the metal constituting the screed (for example 950 C for nickel-chromium); - degradation of the magnet, due to salivary corrosion, which diffuses into the body the toxic materials it contains; - difficulty in producing the associated prosthesis which does not allow correct physiological functioning (compression, pivoting and lateral displacement) to the magnet as well as to the attached prosthesis relative to the gingival bead.

  The invention therefore aims to achieve an attachment and a method of making

  sation of the associated prosthesis which eliminates these various drawbacks.

  To this end, it uses: 1) an attachment which is essentially characterized in that: - the ferromagnetic pellet comprises, over its entire surface, a layer of biocompatible metal; -2- the magnet comprises, over its entire surface, a layer of nickel covered with a layer of chromium itself covered with a layer of epoxy resin; 2) a process for producing the associated prosthesis which is characterized by its simplicity and by its ability to allow correct physiological functioning in the assembly carried out around the attachment in question with

  as a result a significant decrease in traumatic chewing effects

  health on the abutment teeth (broken heaps and abutments).

  The characteristics and advantages of the invention will appear

  more clearly on reading the following detailed description of a mode

  preferred embodiment of the invention given by way of nonlimiting example

  and shown in the accompanying drawings.

  In these drawings: - Figure 1 is an overall sectional view of the attached part of the attachment associated with the dental appliance; - Figure 2 is an overall sectional view of the joint part of the attachment associated with the yoke; - Figure 3 is a sectional view of the joint part of the attachment in progress with the tin washer in the stamped position and the magnet positioned in the cylindrical recess of the yoke; - Figure 4 is a sectional view of the joint and assistant parts of the

  prosthesis finished in rest position (simple support without compression of the magnet).

  Figure 1 shows the attached part of the attachment of the pro-

  finished thesis which comprises a permanent magnet (6) integrated in the part (11) of the prosthesis by means of a cage (13), advantageously made of non-magnetic metal, of which it is integral, which slides in a sheath (14 ), advantageously made of plastic, made integral with said part (11)

  during the realization of the latter.

  An element (7), of the elastic type, is placed between the top of the magnet (6)

  and the bottom of the sheath (14). The cage (13) is closed by resin (19).

  The cage (13) has a conical outer wall facing the cylindrical inner wall of the sheath (14) and a stop (15) capable of limiting the translational travel of the cage (13) and allowing it to pivot in lateral rotation ( tilting) relative to the bottom (16) of the inner shoulder of

  the sheath on which it is supported.

  The magnet (6) comprises, over its entire surface, a layer of nickel (advantageously electrodeposited, avoiding ionic diffusion) covered with a layer of chromium (advantageously electrodeposited, serving to physically protect the previous layer ) itself covered with a layer of epoxy resin (advantageously sprayed, facilitating easy mounting by

  its lubricating appearance and allowing adjustment in its housing).

  Figure 2 shows the joint part of the prosthesis being formed (wax screed) which includes a ferromagnetic pad (1) capable of being integrated in the joint part (12), non-magnetic, of the prosthesis which is obtained by metal casting simultaneous screed (3), covering

  the stump (5) and initially sculpted with wax directly in the master

  model, and a pivot (4), initially made of burn-out material, suitable for

  rer the permanent connection, by sealing, between said yoke (3) and said

stump (5).

  The tablet (1) comprises, over its entire surface, a layer of biocompatible metal, advantageously electrodeposited, such as for example

gold or chrome.

  Figures 3 and 4 relate to the process for producing the pro-

  thesis (joint and joint parts), using an intracoronary magnetic attachment of the kind in question, which is characterized in that it consists of: a) integrating, before the metal casting, in the model of the screed (3), in wax , associated with the burn-out pivot (4), according to FIG. 2, a cylindrical cup (2), in burn-out material, comprising a cylindrical recess (10), with a flat bottom, suitable for receiving, after the metal casting, the ferromagnetic pellet ( 1);

  b) place, on the stump (5) of the master model, a flat flat washer

  able (8), advantageously made of tin, having a central opening (9) of dimensions suitable for allowing the pivot (4) and the base (17) of the yoke (3), the thickness of which (approximately 3 mm) is identical to the thickness of the patch (1) and the outer edges of which cover the gingival bead (18); c) placing the metal yoke (3) on the washer (8) and exerting (fig.3), on said yoke, a pressure capable of stamping said washer so as to make it conform to the surface of the stump (5 ) and that of the gingival bead (18);

  d) place the magnet (fig. 3), by the end of its cage (13), in the housing-

  ment (10) of the screed (3) and seal it with temporary cement (all the space between the screed (3) and the magnet (13,14); e) pouring (fig. 3) the resin the attached prosthesis (11) which coats the sheath (14) which remains integral with it; -4- f) removing the yoke (3), after having detached the magnet (13,14), and the pressed washer (8); g) sealing (fig. 4) the ferromagnetic pad (1) in the housing (10)

of the yoke (3).

  After positioning (fig. 4) the yoke (3) on the stump (5) and sealing the patch (1) in the recess (10) of said yoke, the assistant prosthesis is placed on the joint prosthesis, the cage ( 13) resting on the pad

  (1), and there appears a space between the assistant prosthesis (11) and the padding

  let gingival which allows the compression of the magnet, its pivoting and even

  its slight lateral displacement. The space in question corresponds to

  the thickness of the washer (8) which itself corresponds to that of the pass-

tille (1).

  Thus produced, the prosthesis according to the invention has a physiological functioning adapted to the various masticatory efforts. The root is like this

  freed from all mechanical constraints.

  Its application is particularly indicated in dental implantology.

  In addition to these advantages, the biocompatible ferromagnetic washer used avoids the use of biocompatible ferromagnetic metals for

  make the yokes (3) and the pivots (4) which is an expensive solution.

  In addition, the attachment in question is small.

  For example, they are: - 4 mm for the diameter of the patch (1); - 3 mm for the diameter of the magnet (6) and 2 mm for its height; - 4 mm for the outside diameter of the sheath (14);

  - 3 mm for the total height of the attachment (13,14).

  This allows its implantation in almost all cases of prostheses.

  Of course, the invention is not limited to the embodiments described and shown for which other variants can be provided, in particular: - in dimensions; - in the nature of the materials used;

  without departing from the scope of the invention.

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Claims (3)

  1- Magnetic intracoronary attachment for amo- dental prosthesis   flexible, of the type comprising: a) a permanent magnet (6) capable of being integrated into the adjoining part (11) of the prosthesis by means of a cage (13), of which it is integral, which slides in a sheath (14) made integral with said part (11) during the production of the latter; b) an element (7), of the elastic type, capable of being placed between the top of the magnet (6) and the bottom of the sheath (14); c) a ferromagnetic pad (1) capable of being integrated into the part   joint (12), non-magnetic, of the prosthesis which is obtained by metal casting-   simultaneous connection of a yoke (3), covering the stump (5) and initially sculpted with wax directly on the master model, and of a pivot (4), initially made of burnable material, capable of ensuring permanent connection, by sealing, between said yoke (3) and said stump (5); characterized in that: a) the ferromagnetic pellet (1) comprises, over its entire surface, a layer of biocompatible metal; b) the magnet (6) comprises, over its entire surface, a layer of nickel covered with a layer of chromium itself covered with a layer of epoxy resin; c) a cylindrical cup (2), of burn-out plastic, comprising a cylindrical recess (10), with a flat bottom, capable of receiving, after the metal casting, the ferromagnetic pellet (1); d) a malleable washer (8), advantageously made of tin, having a central opening (9) of dimensions suitable for allowing the pivot (4) and the base (17) of the yoke (3), the thickness of which is identical to the thickness   ferromagnetic pad (1).   2- magnetic attachment according to claim 1, characterized in that the cage (13) has a conical outer wall facing the cylindrical inner wall of the sheath (14) and a stop (15) capable of limiting the travel in translation of the cage (13) and allow its lateral pivoting rotation relative to the bottom (16) of the inner shoulder of the sheath on which it is in support.   3- A method of implementing the attachment according to the claims   1 and 2, characterized in that it consists: a) of integrating, before the metal casting, into the model of the wax screed (3), associated with the burn-out pivot (4), the cylindrical cup (2 ); b) placing, on the stump (5) of the master model, the malleable washer (8) whose outer edges cover the gingival bead (18); c) placing the metal yoke (3), obtained by molding, on the washer (8) and exerting, on said yoke, a pressure capable of stamping said washer   so as to make it match the surface of the stump (5) and that of the stuffing   let gingival (18); d) placing the magnet, by the end of its cage (13), in the housing (10) of the yoke (3) and sealing it with temporary cement; e) pouring the resin from the assistant prosthesis (11) which coats the sheath (14) which remains integral with it; f) removing the yoke (3), after having detached the magnet (13,14) and the pressed washer (8); g) sealing the ferromagnetic pad (1) in the housing (10) of the clevis (3).