US3431183A - Method of making dentures - Google Patents

Description

B. F. REGAN March 4, 1969 METHOD OF MAKING DENTURES Filed June 4, 1965 Z mL TA AT 5 Wm N x m FIE-.2

INVENTOR. BA ERIE F. REG/4N ATTORNE V5 United States Patent Office 3,431,183 Patented Mar. 4, 1969 3,431,183 METHOD OF MAKING DENTURES Barrie F. Regan, 1760 Manor Drive, Hiilsborough, Calif. 94010 Filed June 4, 1965, Ser. No. 461,455 US. Cl. 2044 5 Claims Int. Cl. C23b 7/00; A61c 13/22 ABSTRACT OF THE DISCLOSURE A method of making dentures which comprises essentially electroforming three layers of metals on a replica of the mouth with the first and third layers formed of a tissue compatible metal and the intermediate layer formed of an unstressed metal stronger than the tissue compatible metal. The electroforming operation is interrupted to embed a bubble of stop-01f material in the metal backbone of the denture, and the bubble is subsequently opened and the stop-off material removed to provide an anchor and parting line for gum replica material of the denture.

This invention relates to a method of manufacturing dentures and more particularly to a method of electroforming the metal portions of dentures.

In the art of manufacturing dentures, a variety of techniques are employed for producing a denture backbone which is the structural component of the denture which conforms in shape to the users mouth. The denture backbone is generally formed of a metal and carries a body of material which resembles the users gums and a line of artificial teeth embedded in this body of material. The techniques employed heretofore for manufacturing the backbone" involved the preparation of a replica of the users mouth by first casting an impression of the users mouth and then making from the impression a mouth replica which is a body of material having the same surface as the patients mouth. In the prior practices of forming the denture backbone, Various techniques, such as casting and swaging, have been employed. When the backbone is formed by casting or swaging in this way, the backbone generally does not fit exactly the contour of the users mouth either because of damage to the mouth replica during manufacture or dimensional changes caused by thermal expansion or contraction of cast materials during the manufacturing process.

The technique of electroforming has been used in the past for manufacturing dental backbones as indicated by the following US. patents: 1,453,303, Yaryan; 1,612,605, Beunaventura; 2,335,774, Landry.

The electroforming methods employed in the past have provided certain advantages in the making of metal backbones for dentures in that these electrodeposition methods eliminate dimensional changes in the metal backbone caused by thermal expansion, wear on the mouth replica and contraction of casting materials, but substantial problems have been encountered with electroformed dentures. Thus, when the metal backbone of the denture is electroformed on the mouth replica, the metal backbone will acquire the exact surface configuration of the users mouth, but limitations have been encountered in the metal from which the backbone can be made because the metal to be used must be carefully selected, and the process of its electrodeposition must be carefully selected to provide a metal which is unstressed. In this regard, the metal backbone of the denture is provided with large curved areas, and if the metal of the backbone is deposited under tension or compression, the stress of the metal will deform the metal backbone from its intended configuration. For these reasons, the metal backbone is preferably electroformed from nickel or a nickel alloy which can be deposited in an unstressed condition and which provides sutficient strength for the metal backbone that it will not be bent or damaged in normal use or normal servicing.

When the metal backbones for dentures have been electroformed from nickel, they have been covered with another metal different from the nickel or nickel alloy to provide an exterior metal coating which is compatible with body tissue and will not cause any undesirable taste in the users mouth or irritation to the tissue of the users mouth. When the nickel backbone is covered with another metal in this way, difiiculties are encountered in obtaining good electrical current distribution over the metal backbone when the metal backbone is plated, and the beneficial characteristics of the metal backbone are destroyed because the layer of mouth compatible metal which is plated on the metal backbone changes the configuration of the metal backbone to a sufiicient extent that it no longer provides a perfect fit in the users mouth.

I have found that all of the above mentioned disadvantages of prior methods of making dentures can be overcome, and the metal backbones for dentures can be made with such exact conformity with the surface of the users mouth that a hydraulic seal develops between the tissue of the users mouth and the metal backbone where this hydraulic seal is so strong that unusually good retention of dentures in the users mouth may be obtained.

In accordance with this invention, the metal backbone of a denture is made by electroforming on a replica of the mouth a first layer of metal which is compatible with bodytissue, thereafter electroforming on said first layer a second layer of unstressed metal which is stronger than the metal of the first layer, thereafter electroforming a third layer of metal compatible with body tissue on top of the second layer, with the first and third layers generally made of the same metal, and thereafter removing the composite layers of metal from the mouth replica. In this way, a metal backbone for dentures is provided in which the surface of the backbone which contacts the users mouth tissue has the exact surface conformation of the surface of the mouth replica, and a strong metal backbone having essentially the characteristics of unstressed metal is provided while the surface of the metal in the backbone is compatible with the body tissue.

Additionally, I have found that the manufacture of the dentures may be simplified substantially by forming certain features of the backbone while the backbone is being electroformed. In this regard, metal attachments are often soldered to the metal backbone to provide a finishing line Where the plastic material representing the gum ends, and metal attachments are also soldered to the backbone to lock the plastic material onto the backbone and to form a postdam at the inner edge of the backbone. In accordance with this invention, the electroforming of the backbone may be interrupted and the partially formed backbone modified so that these metal attachments are integrally formed with the backbone as it is electroformed.

Other features and advantages of the invention will become apparent from the following description read in conjunction with the attached drawings in which:

FIG. 1 is a perspective view of a denture made in accordance with the method of the invention;

FIG. 2 is an exploded view of the denture of FIG. 1 illustrating the sequential method of manufacturing the backbone of the denture, and

FIG. 3 is a sectional view on an enlarged scale illustrating a detailed feature of the backbone.

The mouth replica is prepared for electroforming in a manner known to the art where for instance the mouth replica is first sealed with a solution of polyvinyl chloride then sensitized to render the replica electrically conductive by coating the replica with silver paint or chemically reducing a silver, copper or nickel layer on the surface and attaching the replica to the cathode of suitable electroforming apparatus. After the mouth replica is prepared for electroforming, a layer of tissue compatible metal is plated onto the replica, and this tissue compatible metal may be gold, rhodium, chromium, silver or platinum, but gold is generally preferred. The first layer of tissue compatible metal is formed in a thickness of about 0.0005 inch to about 0.005 inch, but preferably less than 0.002 inch.

After the first layer of tissue compatible metal is formed, an intermediate layer (not shown on the drawings) may be formed if it is desirable to reduce the thickness of the first layer and provide an intermediate layer of high hardness and thermal conductivity between the first layer and the central body layer of the backbone. This intermediate layer, if desired, may be in a tin nickel alloy formed of 65 percent tin and 35 percent nickel.

After the first layer of tissue compatible metal has been formed, and after any intermediate layer is formed, it it is desired, the central body portion of the metal backbone is electroformed as a second layer. This central second layer of the backbone is preferably formed of unstressed nickel made for instance in accordance with the sulfamate nickel plating process, This second layer is formed in a sufiicient thickness, preferably about 0.015 inch, to provide substantial strength and durability in the metal backbone.

After the second or central body layer of the metal backbone is electroformed, an additional intermediate layer of silver or tin nickel may be electroformed as mentioned above, and there after the backbone is ready to receive its final or third layer.

The third layer is electroformed in the same way as the first layer and preferably of the same tissue compatible metal, and after the third layer is completed, the electroforming of the metal backbone is finished. The metal layers homogeneously bonded to each other are then removed from the mouth replica in any convenient way, and the peripheral edge of the backbone may be trimmed to provide the exact size metal backbone desired for the denture. If the backbone is trimmed after it is removed from the electroforrning operations, the edges of the intermediate layers of the backbone should be masked at the edge of the backbone, and this may be accomplished simply by masking the entire metal backbone with a non-conductive material before the edge of the backbone is trimmed and then electroplating a tissue compatible metal onto the backbone before the masking material is removed.

As indicated above, it is often desirable to provide modifications of the metal backbone at the finishing line, the postdam, and other points on the backbone to which plastic material resembling the users gums will be attached. These modifications may be accomplished most efiiciently during the electroforming of the metal backbone to eliminate additional work on the backbone after it is electroformed and to provide these modifications in a way where the plastic material of the denture will be firmly locked into the center nickel layer of the backbone.

Thus, FIG. 3 illustrates one technique which may be employed in accordance with this invention for making the finishing line of the denture Where the plastic material of the denture ends and a retention bar which locks the plastic material onto the metal backbone. The backbone is provided with two continuous bubbles and 12 running around the circumference of the backbone along the tooth receiving area thereof,,and the bubbles 10 and 12 are slotted at 14 and 16 respectively. The slot 14 runs along the finishing line of the denture so that when the plastic material 18 resembling the users gums is applied to the denture, the plastic material 18 will penetrate into the bubbles 10 and 12 locking itself to the backbone, and the plastic material 18 i appe r t9 en at the lidge of the slot 14 thereby defining a clean finishing line in the denture.

The bubbles 10 and 12 may be formed very efiiciently during the electroforrning of the metal backbone by interrupting the electroforming of the central nickel layer when the central nickel layer has reached approximately onehalf of its intended thickness. Thus, the partially formed metal backbone may be removed from the electroforming apparatus after the central nickel layer has been formed to a thickness of about 0.007 inch, and a ribbon of wax may be applied around the inner and outer circumferences of the partially formed backbone in the areas which the bubbles 10 and 12 are to occupy. The top surface of the wax is then sensitized to conduct an electric current, and the partially formed metal backbone is returned to the electroforming apparatus to complete the electroforming of the center nickel layer to its thickness of about 0.015 inch.

Thereafter, the surfaces of the two bubbles 10 and 12 may be slotted with a suitable knife or the like, and the wax in the bubbles may be dissolved or otherwise removed to leave hollow interior bubbles into which the plastic material 18 may be extruded when the denture is finally made.

Other methods may be employed for modifying the backbone during the period when it is being formed. For instance, instead of forming the retention bar as a bubble 12, the formation of the bubble 12 may be eliminated, and instead, a series of holes may be drilled in the central nickel layer after the central nickel layer is completed and before the third layer of tissue compatible metal is applied. In this way, the electroforming of the final tissue compatible layer will deposit tissue compatible metal at the edges of the drilled holes without depositing substantial metal in the bottom of the holes. When the plastic material 18 is later extruded into the holes, it will be effectively locked into the holes by the converging side walls of the holes.

While one specific embodiment of the invention has been illustrated and described in detail herein, it is obvious that many modifications thereof may be made without departing from the spirit and scope of the invention.

I claim:

1. The method of making a metal backbone of a denture which comprises electroforming on a replica of the mouth a first layer of metal selected from the class consisting of gold, silver, chromium, rhodium and platinum, which is compatible with body tissue, thereafter electroforming on said first layer a second layer of a substantially unstressed metal which is stronger than the metal of said first layer, thereafter electroforming a third layer of a metal compatible with body tissue on top of said second layer, and thereafter removing said layers of metal from said replica.

2. The method of claim 1 characterized further by the inclusion of the steps of: interrupting the electroforming of said second layer to produce a partially formed metal backbone, modifying said partially formed metal backbone by applying a stop-off material thereto to prevent further electroforming in a portion of the space adjacent to the surface of said partially formed metal backbone, resuming the electroforrning of said second layer to complete said second layer with spaces therein having side walls sloping toward each other and away from said first layer, and removing said stop-off material from said backbone.

3. The method of claim 1 characterized further by the inclusion of the steps of: interrupting the electroforming of said second layer, applying on top of the partially formed second layer and along the finishing line of the denture backbone a continuous strip of a material different from the metal of said second layer, resuming the electroforming of said second layer to complete said second layer with said strip of material embedded therein, cutting a slot narrower than said strip of material into said 5 strip of material along the finishing line of the denture backbone, and removing the strip of material from said metal backbone to leave a cavity in said second layer communicating with the finishing line.

4. The method of making a metal backbone of a denture provided with surfiace modifications for attachment to denture material representing human gums which comprises: electroforming on a replica of the mouth a layer of metal, interrupting the electroforming of said layer of metal to produce a partially formed metal backbone of predetermined thickness, modifying said partially formed metal backbone by applying an electrical stopoif material thereto to prevent further electroformiug in a portion of the space adjacent to the surface of said partially formed metal backbone, resuming the electroforming of said layer of metal, continuing to electroform said layer of metal until said backbone has a thickness of at least about twice said predetermined thickness, and removing said stop-off material from said backbone.

5. The method of making the metal backbone of a denture which comprises electroforming a layer of metal on a replica of the month, interrupting the electroforming of said layer to produce a partially formed metal backbone of predetermined thickness, placing on the surface of said partially formed metal backbone in a local area thereof a body of material different from the electrodeposited metal in said partially formed b ckbone, resuming the electroforming of metal on top of said partially formed metal backbone and on top of said body of material and continuing said electroforrning until the thickness of said backbone is about twice said predetermined thickness to produce a metal backbone containing a bubble filled With said body of material, opening said bubble, and removing said body of material from said metal backbone.

References Cited UNITED STATES PATENTS 1,453,303 5/1923 Yaryan 204-4 2,335,774 11/1943 Landry 204--4 JOHN H. MACK, Primary Examiner.

T. TUFARIELLO, Assistant Examiner.

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