In-situ Denture, Means And Method

Abstract

Enclosed are devices and methods for forming a denture in-situ in the mouth of a dental patient. An impression of the gums is made in an impression material through a spacer in a tray holding false teeth. The tray with the impression therein is removed from the mouth, the spacer removed and the top surface of the teeth exposed to provide a former into which liquid curable denture-forming material is then placed. The resulting assembly is then inserted into the mouth where pressure is applied and the resin cures to form the denture which is thereafter separated from the former which comprises the tray and impression material.

Parent Case Text

This application is a continuation-in-part of our copending applications Ser. No. 126,507, filed Mar. 22, 1971 and Ser. No. 241,706, filed Apr. 6, 1972 and both applications are now abandoned.

Description

In U.S. Pat. No. 3,460,252, there is described various means and methods for forming a denture in-situ in the mouth of a dental patient. In U.S. Pat. No. 3,621,575, there is described various improvements in or relating to in-situ dentures involving the use of a gutter shim and/or different curable denture-forming materials.

An object of the present invention is to provide improvements in the in-situ formation of dentures.

Another object is to provide new and improved devices for use in the in-situ formation of dentures.

A further object is to provide new and improved methods for the in-situ formation of dentures.

These and other objects of the present invention will be evident from the following description of the invention and accompanying drawings in which:

FIG. 1 is a perspective view showing an upper tray without teeth therein;

FIG. 2 is a perspective view showing a lower tray with teeth therein;

FIG. 3 is a section taken along line 3--3 of FIG. 2.

FIG. 4 is a top view showing an upper tray having a cast set of false teeth therein.

FIG. 5 is a view showing a tray in elevation and in section taken along line 5--5 of FIG. 4.

FIG. 6 is a top view of an upper tray having impression material therein and a spacer over said impression material with cutaways showing the impression material and teeth beneath the impression material.

FIG. 7 is a vertical section taken along line 71'7 of FIG. 6.

FIG. 8 is a top view of upper former comprising the upper tray in which an impression has been formed and from which any impression material covering the teeth has been removed.

FIG. 9 is a vertical section taken along line 9--9 of FIG. 8.

FIG. 10 is a perspective view of a porous gutter type shim preferably used in conjunction with a lower tray or former.

FIG. 11 is an exploded view showing an upper former having a layer of resin thereon and a porous shim above said former for placement on said resin.

FIG. 12 is a schematic illustrating a step-by-step procedure for preparing a former for use in the formation of the denture.

FIG. 13 is a top view of a finished upper denture within a former.

FIG. 14 is a vertical section taken along line 14--14 of FIG. 13.

FIG. 15 is a vertical section taken along line 15--15 of FIG. 13.

FIG. 16 is a vertical section of a finished denture after removal of the former and presented as if taken along line 14--14 of FIG. 13 after removal of the former comprising the tray and impression from the assembly shown in FIG. 13, and

FIG. 17 is a perspective view of a spacer for making a lower former.

Referring to FIGS. 1-5 there is shown a thin flexible tray 20 which is preferably formed of a thin flexible plastic preferably in the family of ethylene or propylene polymers or copolymers. The tray can be vacuum formed from a sheet of material. The tray could also be formed by any other known method such as injection or blow molding. The tray 20 is used for making an upper denture and the tray 22 is used for making a lower denture.

The upper tray 20 has the general shape or outline of the arch of the mouth and comprises an outer uprising flexible wall 24, an inner uprising flexible wall 26 and a palate portion 28. The inner and outer wall portions are interconnected along the integral bottom portion 29 of the tray.

The lower tray 22 has the general shape and outline of the arch of the mouth and also includes a flexible outer uprising wall 24 and a flexible inner uprising wall 26, which walls are interconnected along the integral bottom portion 29 of the tray.

The outer wall 24 and inner wall 26 together with the bottom portion 29 can be taken collectively as forming a trough 30 of which the upper portion is a gum-receiving portion 32 designed to receive a patient's gums and of which the lower portion is designed to receive false teeth, the gum-receiving portion having a bottom defined by or including the exposed tops of the false teeth which are to be subsequently joined to denture-forming material. The trough 30 including the lower portion thereof is relatively narrow at the forward portion 36 of the tray and gradually increases in width along the side portion 38 of the tray as shown particularly in FIG. 4. Thus, the teeth are snugly held in the tray.

Impressed within said lower portion of the trough 30 of the tray 20, as during molding or by any other suitable method of indicating, is indicia or cavities 40 preferably in the form of spaced or successive depressed pocket portions 40 which desirably are openly interconnected continuously along the arch of the lower portion of the trough. The indicia 40 indicate to the user the proper placement of the false teeth 42 within the tray 20 prior to making the dentures. Each tooth is thus snugly held within a depression or pocket 40 and the teeth 42 are further held because the trough 30 increases gradually in width. The teeth 42 are therefore supported and cannot readily move out of place. Thus, there can be no leaning or turning movement of the teeth and alignment is always insured. The false teeth employed in the invention and disposed within the depressed portions 40 may be provided as a single cast unit containing all necessary teeth as shown in the drawings, or may be provided by a plurality of teeth sections containing one or more teeth, or may all be provided as individual teeth which may or may not be held by a binder material such as silicone rubber as described in U.S. Pat. No. 3,460,252, and in U.S. Pat. No. 3,621,575.

Both the upper tray 20 and lower tray 22 desirably have a small outward step 41 which is more pronounced towards the rear of the tray than the front and which may be more pronounced with respect to the outer walls 24 than the inner walls 26. The steps 41 allow for the space to be taken by the impression material, while also taking into account the natural stepping out of the gums from the teeth. When false teeth are to be positioned in the cavities 40 without the aid of a binder, then it will be evident that the step 41 will be further more pronounced to account for the natural stepping out of the gums from the teeth, as shown for example in FIGS. 3 and 5.

The tray 20 with teeth 42 therein as shown for example in FIGS. 4 and 5 may be prepared for use in formation of the denture by depositing an impression material in the tray and distributing the impression material 43 over the inside surfaces of the outer wall 24, the inner wall 26 and the palate portion 28, as shown in FIGS. 6 and 7. In a preferred embodiment, the upper exposed surfaces of the teeth 42 are also covered so that the impression material 43 is essentially distributed over substantially the entirety of all of the available surfaces in the inside of the tray, as also shown in FIGS. 6 and 7. The impression material may be any of several known types of materials which are suitable for obtaining an impression of the characteristics or contours of surfaces and which are safe for use under the conditions contemplated herein. It has been found that alginate based impression materials commonly employed as impression materials in the denture field may be very satisfactorily employed and may be prepared by standard techniques involving the mixture of dry alginate and water to a paste having a consistency suitable for use in obtaining an impression of the gums of a patient in the denture field.

When employing an impression material prepared, for example, from alginate and prior to depositing the same in the tray, it has been found desirable to first coat the available inner surfaces of the tray with an adhesive material adapted to promote or effect adhesion of the impression material to said inner surfaces of the tray. Such application of a layer of adhesive material (not shown except in FIG. 12) insures against the impression material separating from the tray surfaces after the impression is taken. A suitable adhesive which may be used with alignate is a water-based latex pressure sensitive adhesive and another suitable material is obtainable under the trade designation "Gel-Grip." When an adhesive is used it is desirably applied to all available inner surfaces of the tray 20, i.e., the inside surface of the outer wall 24, the inside surface of the inner wall 26 and the inside surface of the palate portion 28, except that the exposed surfaces of the teeth 42 and the small surface areas of the tray between the teeth are not painted or coated with the adhesive.

The tray 20 with the impression material 43 therein is then ready for insertion into the mouth of the patient after locating a spacer 44 in an appropriate position relative to the tray so that the impression of the patient's gums will be obtained by the application of pressure to and through the spacer 44. The basic purpose of the spacer 44 is to allow for and take up approximately the space to be later occupied by denture-forming plastic material at least in the more critical areas which are adjacent to the outer wall 24 and the inner wall 26. It will therefore be evident that the spacer 44 may be made from any of several suitable materials and may be pre-formed to adapt to the shaping of the tray or may be a sheet material which can be shaped under mild pressure to take the shape of the tray. When employing a sheet material as illustrated in FIG. 12 it is preferred to employ a material which has satisfactory drape properties so that it will approximately conform to the shape of the tray and gums and palate of the patient without substantial bunching or overlapping, thereby avoiding the production of an untrue impression. A sheet material providing satisfactory results is a sheet of pure gum rubber. A sheet of such material also has the important property of being shapeable without being excessibly compressible so that the thickness necessary to compensate for subsequent denture-forming plastic may be more easily maintained and controlled. A suitable spacer having a uniform thickness of about 0.0625 inch may be made simply by cutting an arch shaped piece from a commercially available sheet of pure gum rubber. Another suitable spacer is similary made fro 0.100 to 0.125 inch thick "Minicel" L-200 cross-linked polyethylene foam. A preferred pre-formed spacer is readily made from Boxing Wax which is well known material in the dental art. While satisfactory results are obtainable employing a spacer of uniform thickness, it will be evident that a spacer having a non-uniform thickness may be employed to provide for areas in which it will subsequently be desired or required to have a lesser or greater thickness of the plastic denture material. For example, the thickness of the palate area of the spacer may be greater to provide a denture having a greater thickness of plastic denture material in the palate than in other areas.

The spacer 44 is placed in an appropriate position over the impression material 43 in the tray 20, for example, as illustrated in FIG. 12, and the resulting assembly inserted into the patient's mouth as also illustrated in FIG. 12. Mild pressure is then applied through the spacer 44 by the patient and/or dentist to form an impression of the patient's upper gum and palate in the impression material. The tray with the impression formed therein is removed from the patient's mouth. When employing alginate and the like it is preferred to hold under pressure in the mouth for about 2 to 5 minutes prior to removal to allow for sufficient setting up of such impression materials so that the impression will be sustainable in subsequent steps.

After removal of the tray with the impression therein from the mouth the spacer is carefully removed to avoid disturbing the impression formed in the impression material. Any excess impression material over-flowing the tray may be easily removed by running a dull knife over the edges of the tray. The impression material which also covers the teeth 42 after the impression is taken is then removed by any suitable means as by cutting with a dull knife to form an arch shaped channel 45 which exposes all of the top surfaces of the teeth 42 and also the surfaces of the tray 20 which are between the maximum horizontal extension of adjacent teeth, as illustrated in FIG. 8. Side walls 46 of the channel 45 are desirably smoothed out or otherwise made to incline outwardly from the bottom of the channel formed by the top surfaces of the teeth so that subsequently the junction between the top side edges of the teeth and plastic gum-forming denture material will give as natural an appearance as possible, as shown particularly in FIG. 9. The resulting assembly which is shown in FIGS. 8 and 9 constitutes an adapted upper tray or upper former 50 which is specifically adapted to the individual patient by reason of the impression and spacer and which is also specifically adapted to pre-establish more or less the desired thickness of the denture by reason of the spacer. The upper former 50 as shown in FIGS. 8 and 9 therefore comprises the tray 20, an uprising outer impressed wall 54 supported by and/or bonded to the tray uprising outer wall 24, an uprising inner impressed wall 56 supported by and/or bonded to the tray uprising inner wall 26, an impressed palate portion 58 supported by and/or bonded to the tray palate portion 28, and a channel 45 exposing the teeth 42 carried by the tray 20. A lower former (not shown) for use in making a lower denture may be prepared analogously to the upper former 50 and will therefore comprise a lower tray 22, a8 uprising outer impressed wall supported by and/or bonded to the lower tray outer wall 24, an uprising inner impressed wall supported by and/or bonded to the lower tray inner wall 26 and a channel 45 exposing the teeth 42 carried by said lower tray 22. FIG. 17 illustrates a spacer 44a for making a lower former.

While it is preferred to form the former of the invention by obtaining the impression of the patient's gums in the impression material by working in the mouth of the patient, it is also suitable to form the former outside of the mouth by employing a stone impression of the patient's gums. Such stone impression may be prepared in the conventional manner by tking a conventional alginate impression of the gums and then casting the thus obtained impression in stone in the usual way. The assembly for forming the former comprising a tray with impression material distributed therein and covered by a spacer may be then placed over the stone impression and the impression of the patient's gums in the impression material obtained by the application of mild pressure through the spacer as previously described.

In the preferred method for preparing a former as above-described it is indicated that the impression material covers the teeth during the taking of the impression and is subsequently removed to form a channel 45 in which the teeth are exposed. It will be noted that other methods may be employed to obtain a former with the desired channel 45 exposing the teeth. For example, an arch shaped space-maker (not shown) having the general shape and width of the desired arch like or U-shaped channel 45 and thickness which is less than or approximately the desired thickness of denture forming material in this area may be placed over the teeth prior to deposition of the impression material, and later removed along with any impression material which may be on it after the impression is taken thereby providing the desired channel 45 in which the teeth and surfaces of the tray between the maximum horizontal extension of adjacent teeth are exposed.

One objective achieved by the instant invention is the provision of a former which is individually adapted to the patient's gums yet provided or prepared from a basic tray which can be adapted by the invention to a number of different patients, thereby reducing the number of trays which must be made available to take into account the wide variations in the pertinent contours of dental patients. In this connection, it can be appreciated that the palate area is subject to fairly wide variations and constitutes an area in which it is highly desirable to control the thickness of the denture. Accordingly, in an alternative embodiment of the invention for making an upper denture, many of the advantages of the invention may be realized by preparing a former in which only the palate portion and the inner wall are covered with impression material leaving the outer wall uncovered by impression material. Such a former may be prepared in a modification of the procedures above described by distributing impression material, e.g., alginate, over the palate portion 28 and inner uprising wall portion 26 of an upper tray 20, preferably after coating the surface of said palate portion an inner wall with an adhesive. A spacer 44 may then be placed in an appropriate position over the impression material and uncovered inside surface of the outer wall portion 24 and athe resulting assembly inserted into the mouth of the patient where mild pressure is applied to obtain an impression of the palate and inside surface of the upper gum of the patient. Upon removal from the mouth the spacer is separated from the tray and any impression material covering the teeth is removed to provide a modified upper former comprising the tray, an uprising inner impressed wall supported by and/or bonded to the tray uprising inner wall and an impressed palate portion supported by and/or bonded to the tray palate and integral with the inner impressed wall, said former having the teeth exposed at the bottom of its gum-receiving portion and the inside surfaces of its outer wall substantially free of impression material. Such a modified former may be employed to form in-situ a denture in accordance with the invention. In addition, such modified former may be further modified to obtain or permit the obtaining of fully adapted or conformed trays by securing a formable material such as wax or other suitable material to the outside of the outer wall whereby said outer wall may be conformed through the spacer to the outside surface of the upper gum of the patient, essentially as indicated and according to the technology disclosed in our above-identified application Ser. No. 241,706.

The former 50 comprising the tray 20 with the impression formed therein and with the channel 45 exposing the upper surfaces of the teeth 42 is now ready to receive gum-forming denture material in the final major phase leading to the formation of the denture. Such formation may be carried out in accordance with the basic method described in U.S. Pat. No. 3,460,252 whereby gum-forming or curable denture material is deposited in the former and distributed over the exposed surfaces of the teeth 42 and intervening exposed surfaces of the tray 20 and over the surfaces of the impressed walls 54 and 56 and impressed palate portion 58. If desired, a palate shim (not shown) covering at least about the major portion of the palate portion may be used to control the thickness of the palate portion during formation of the denture and in the resulting denture, as described in said U.S. Pat. No. 3,460,252. The resulting assembly comprising the former 50 with denture-forming material therein is then inserted into the mouth of the patient where the gum-forming material cures rapidly to at least retain the shape of the gums. Upon removal from the mouth the former 50 may be readily separated from the formed denture by using a dull knife or the like to remove the tray 20 which usually carries a substantial portion of the impression material with it. Any impression material remaining on the formed denture may also be removed by means appropriate for the particular impression material. For example, when employing alginate such impression material will be still moist after formation of the denture and may be removed by a stream of water and wiping with a soft cloth.

The denture of the present invention may also be prepared in accordance with the above-referred to U.S. Pat. No. 3,621,575 involving the use of a channel like flexible gutter shim, preferably in conjunction with different types of gum-forming materials. The structures involved in and/or resulting from such preparation are shown in FIGS. 10, 11, 13, 14, 15 and 16. The channel like flexible gutter shim means may be a separate individual component such as the more or less arch shaped gutter shim 59 shown in FIG. 10 for use preferably with a lower former in making a lower denture but which may also be used in the upper former 50, or may be taken as forming a gutter section 62 of an integral complete shim 60 shown in FIG. 11 for use with the upper former 50 in forming an upper denture. A separate individual gutter shim of the type of shim 59 may be used alone or in combination with a separate palate shim (not shown) in formation of the upper denture, but it is preferred to employ the complete shim 60 in forming the upper denture. Thus, the preferred complete shim 60 comprises generally a palate portion 61 and a gutter section 62 integrally therewith, said gutter section 62 comprising a bottom portion 63 integral with an outer uprising wall portion 64 and inner uprising wall portion 65 forming a shim trough adapted to receive gum-forming material and the patient's gum. As shown in FIG. 10, the gutter shim 59 also comprises the outer uprising wall 64, inner uprising wall 65 and bottom portion 63 integral with said inner and outer walls forming a trough adapted to receive gum-forming material and a patient's gum. The gutter shim 59 or gutter shim section 62 is designed to be placed and fit loosely in the gum-receiving portion 32 in the upper portion of the trough 30 where the gum-forming denture material is deposited. The shims are therefore desirably sized and shaped accordingly such that the shape and contours thereof appropriately conform to the shape of the tray and former including the palate portion in the case of the upper tray and former when using the shim 60, in any event taking into account that the shims will be placed on a first layer of denture material deposited in the former. However, it is not necessary that the upstanding wall portion 64 or a complete shim 60 or either upstanding wall portion of the gutter shim 59 exactly parallel the corresponding portions of their respective formers as the preferred shims are flexible and deviations from the optimum are corrected by the gum-forming denture material flowing on the opposing sides of such shims during the formation of the denture in the patient's mouth. The shims 59 and 60 may be made from any of several materials, i.e., fabrics, including fabrics which are solid non-porous materials or porous materials has hereinafter described. In general, it is preferred that the shim be composed of sufficient acrylic material to obtain the benefit of a like-to-like bond with the acrylic denture-forming material. It is also preferred that the shims be pigmented or otherwise colored pink or the color of natural gums to promote obscurity within the denture. In general, the shims have thickness in the range of from about 0.02 inch to 0.12 inch, preferably between about 0.02 inch to 0.07 inch.

The shims used in the formation of a denture are preferably porous shims, the term "porous" being used herein in the open communicating sense to indicate a depression or opening communicating with at least one of the two opposing surfaces of the shim, the shims more preferably having porosity which is "through" porosity in the sense of communicating between both opposing surfaces of the shim. The porous shims generally have the property of restraining, holding and/or absorbing curable liquid denture-forming material during denture formation. On the other hand, the porous shims also have substantial surface area or bulk so that the shims should not be merely a component having very large openings formed by a very thin network of supporting structure. The porous shims desirably have a porosity or open volume of at least about 15 percent ranging up to about 85 percent, preferably between about 25 percent to 75 percent. The preferred shims having through porosity have their openings of a size at least sufficient to permit the flow of curable liquid resin material from one side of the shim to the opposite side or to a central portion thereof sufficient to be joined to liquid material flowing from said opposite side under the mild pressure applied during in-situ denture formation and before substantial curing of the resin, i.e., within a period of no more than 3 to 15 minutes. The shim is preferably at least sufficiently porous to be readily permit the flow of liquid resin material therethrough. The porosity is preferably provided in the shims by a plurality of separate surface opening preferably measuring in the range of from about 0.007 inch to 0.13 inch, more preferably in the range of from about 0.02 inch to 0.06 inch, as measured as an average through the center point of the openings which are preferably circular or rectangular openings of more or less equal length sides. Increasing the size of straight through continuous openings communicating between opposing shim sides in excess of about 0.15 inch tends to increasingly depreciate the benefits of using such a porous shim and thus such large openings are desirably avoided in any significant number in the porous shims. The preferred shims approximate a screen size in the range of from 6 to 80 Tyler Standard Mesh, and the more preferred shims approximate a screen size in the range of from 10 to 35 Tyler Standard Mesh.

The porous shim may be fabricated from any of a variety of fabrics and the term "fabric" is used herein in its broad sense. It is of course required that the fabric be capable of being shaped into the desired shape of the shim. However, such ability to be shaped may be inherent in the fabric per se and shaping accomplished by such conventional methods as pressing, stamping, molding, vacuum forming and the like, or may be accomplished by treatment of the fabric with a stiffening material, for example, by lacquering, varnishing, coating, painting and the like. The shim may thus be prepared from a sheet of any of a variety of materials or fabrics such as thin plastic sheets or foil of metals which have or will be stamped or perforated or otherwise processed to obtain the desired porosity, or from fabrics which are known conventionally in the textile art as non-woven fabrics or from materials which are woven fabrics. In general, it is preferred that the shim be of an acrylic material to the extent of containing some portion of an acrylic resin or polymerized acrylic monomer sufficient to provide the better bond obtainable between the shim and the gum-forming plastic material on the basis of like material being bonded to like materials. Very good results are obtained with treated or stiffened woven fabrics. The preferred shims are therefore formed of woven fabric composed of acrylic strands by shaping the acrylic fabric and treating as by bushing or painting with a solvent solution of an acrylic monomer followed by drying to obtain the shaped shim. An example of such a solvent solution is a methyl methacrylate resin dissolved in a mixture of toluene and methyl ethyl ketone. A preferred such woven acrylic fabric has been obtained under the trademark DYNEL and is composed of about 0.0196 inch thick threads of a modified acrylic polymer containing 35-85 percent acrylonitrile and having 22 .times. 20 threads per inch. The shim may be composed of a single layer of such preferred fabric or may be a laminate prepared by bonding together as by painting together or the like two overlapping layers of the preferred acrylic woven fabric. In general, the use of a porous shim provides distinct advantages and improvements realized both during the in-situ formation of the denture and in the resulting denture itself. However, the use of a shim may be dispensed with in carrying out the present invention as significantly less denture-forming material is usually required compared with the usual requirements for forming an in-situ denture without the adapted tray or former provided by this invention. Hence, the problems of controlling the flow of denture material during the in-situ formation by this invention are substantially reduced although it is still preferred to employ a shim in conjunction with two different denture-forming materials in carrying out the present invention as hereinafter described.

In the method of forming an upper denture as shown in FIGS. 11, 13, 14, 15 and 16 employing a complete shim 60 a first layer of denture material 66 is deposited in the upper portion of the trough 30 and in channel 45 and over the teeth 42, and over the remainder of the exposed surface area of the impressed walls 54 and 56 and impressed palate portion 58. The complete shim 50 is then placed in position on the first layer of denture material 66 and desirably in such a manner that the denture material 66 is in wetting contact with the entire underside area of the shim 60, except that the upper end portion of the upstanding wall portion 64 may be left free of denture material. Alternately and preferably, the denture material of the first layer in the palate area may be applied directly to the underside of the palate portion of the shim before placing the shim in contact with the former. A second layer of gum-forming or denture material 67 is then deposited on the upper exposed surface of the shim 60 covering the exposed upper area of the shim 60 vertically above the teeth, and then spread or applied to cover the entire exposed area of the shim 60 including the palate portion except that the marginal or horizontal ridge portion of the upstanding wall 64 of the shim 60 may be left uncovered as this portion will be subsequently covered and surrounded by denture material flowing under the pressure applied during the denture formation. When the denture materials are spread over all appropriate surfaces the ratio by volume of denture material 66 in the first layer to denture material 67 in the second layer is suitably in the range of about 1:3 to about 1:1, and is preferably approximately 2:3. The preparation of a denture-forming assembly employing a gutter shim 59 for use in forming a lower denture in conjunction with a lower former is accomplished analogously using two layers of denture material, as described. The resulting assembly for forming an upper or lower denture employing a complete shim 60 or gutter shim 59 is then ready for placement in the mouth of the patient and formation of the denture in the manner described.

In general, the gum-forming or denture material is a cold curing pigmented mixture consisting of a powder and a liquid. The powder is a polymer preferably of the acrylic family. Certain acrylic copolymers containing vinyls or styrene can also be used. The liquid material is preferably an acrylic monomer or mixture of acrylic monomers such as methyl methacrylate and butyl methacrylate. Such materials are well known and used in the prior art, for example, as denture repair materials. The powder and/or liquid contain small quantities of known catalysts which interact to cause curing and hardening of the mixture within a short time without any external heat source. The denture material may a so-called "rigid" denture material or a more flexible type denture material and the distinction between rigid materials and other materials which are less rigid and softer is well recognized in the denture art. Cold-curing resins used in the denture art often have varying tendency to cause discomfort during curing in contact with the gums of a dental patient primarily because of a stinging sensation which may or may not be reasonably tolerated by the patient. Contact of the curable resin with the gums of a patient's mouth may be avoided by enclosing the denture-forming assembly in a thin envelope as described in U.S. Pat. No. 3,460,252. The use of such a protective envelope may be dispensed with however by selecting denture materials more suitable for direct contact with the gums without causing any substantial discomfort. Such a more suitable rigid type material is available commercially under the tradename "Truliner" and another under the tradename "Duraliner," and such a more suitable soft type material is available commercially under the tradename "Soft-Line." Components for another more suitable and preferred semi-hard denture material for use in the invention have been obtained on special order from the American Consolidated Manufacturing Company of Phila., Pa., and such material is prepared by mixing in a ratio of 10.3 gms. of a powder component obtained as special order component 3-A with 8.0 cc. of a liquid component obtained as special order component 2-A.

As described in U.S. Pat. No. 3,621,575 both a rigid and semi-rigid denture material may be used in combination with distinct advantages in the in-situ formation of a denture in the mouth of a dental patient. Thus, as shown particularly in FIGS. 11, 13, 14, 15 and 16, the first layer of denture material 66 may be a rigid denture material while the second layer of denture material 67 is a semi-rigid denture material. As shown particularly in FIG. 16, the use of both such types of denture materials make it possible to form a final denture 68 in which the outer surfaces of the denture including both the gums and palate portion normally exposed to saliva, food, smoke and the like are formed of a rigid material and the false teeth joined to the formed denture by such rigid material, while the inner or non-exposed surfaces of the denture in direct contact with the gums and palate are formed of a semi-rigid material. The use of the semi-rigid denture material 67 has been found desirable in an in-situ formed denture because of the closeness of the fit and conformity to the patient's gums, thus permitting greater comfort and greater ease in the removing and installing of the denture. The use of a semi-rigid denture material 67 is also highly desirable when the gums of the patient have unusual protuberance or undercut areas which might otherwise become troublesome if a rigid material were used in an in-situ formed denture. On the other hand, the denture shown in FIG. 16 has its outer or exposed surfaces composed of a rigid material which has the known advantages of a rigid denture material including resistance to denting, loss of shape, staining, discoloring and the like. A lower denture (not shown) may be similarly prepared employing the combination of rigid and semi-rigid denture materials. It will also be noted that the use of a gutter shim 59 or complete shim 60 having a gutter section 62 facilitates and improves the formation of dentures utilizing different denture materials, e.g., both a rigid and semi-rigid denture material.

The denture art well recognizes the distinction between rigid denture materials and those other materials which are less rigid and softer and such other materials are referred to herein as "semi-rigid" materials. For purposes of definition herein we divide the semi-rigid materials into two sub-clases referred as "semi-hard" and "soft" denture materials respectively. A suitable distinction for purposes of the description thereof may be made according to the conventional 3 point Deflection Test given in the INTERIM FEDERAL SPECIFICATION W-R-00179a (DSA-DM) of Feb. 20, 1967, suc that a "rigid denture material will have a maximum deflection not exceeding about 1.7 millimeters when determined in accordance with the standard test under an initial 1,500 gm. load increasing to a maximum 2,500 gm. load while a "semi-rigid" denture material has a deflection exceeding 1.7 millimeters. The semi-hard materials are further defined herein as having a deflection in the range of deflections exceeding 1.7 but not exceeding about 4.0 while those exceeding a deflection of 4.0 are defined as soft materials. Preferably, the rigid material has a deflection between about 1.0 to 1.5 millimeters while the preferred semi-hard material has a deflection between about 1.8 to 3.5 millimeters. The semi-hard materials are those preferred for use in combination with a rigid material in forming a denture as described herein.

The combined advantages provided by the present invention in the in-situ formation of dentures include the need to have available only a few number of trays in order to have a tray of appropriate size for most any patient; the ability to have an adapted tray or former very precisely and uniformly conforming to the arch and palate of the patient; the ability to form a denture in which the outer surfaces of the gums simulate the contours of the actual outer gum surfaces of the patient; the ability to predetermine fairly closely the amount of gum-forming material to be used and accordingly the ability to predetermine fairly closely the amount and thickness of the plastic denture material in the final denture; the use in general of significantly less gum-forming material in the preparation of an in-situ formed denture; and the production of an in-situ formed denture more closely approximately a custom made denture in several aspects.

The following is representative of a step-by-step procedure for forming an upper denture in accordance with a preferred embodiment of the invention and in which reference may be made for further clarity to FIG. 12 which illustrates the preparation of an upper former from a tray i3 the successively dramatized Steps A, B, C, D and E of that figure.

A. A tray of approximately appropriate size containing a cast set of acrylic teeth of correct or desired shade is selected to provide an assembly such as illustrated in FIG. 3 and Step A of FIG. 12. This assembly is inserted into the mouth of the patient for purposes of arriving at the correct fitting and alignment of the tray and determining necessary adjustments. The vertical fitting of the tray is determined by establishing the desired distance allowing for denture material between the teeth in the ray and lower ridge of the gum in the front of the mouth and determining to what extent, if at all, the upper portion of the outer uprising wall of the tray must be trimmed to obtain such distance during the forming step. Any excess portions of the plastic tray wall are then readily trimmed or removed with a scissors. Lateral fitting of the tray is determined with reference to the back portion of the tray by establishing the gum in the gum-receiving portion of the trough and determining whether the particular tray is too wide or narrow, taking into account that both impression and denture material will be present in the trough in addition to the gums of the patient. If lateral correction is required another tray having approximately the appropriate lateral size is selected and fitted vertically.

B. The inside surfaces of uprising outer and inner walls and palate portion of the tray are then painted with a thin coating of "Gel-Grip" adhesive while taking care not to paint any of the adhesive on the teeth or on the exposed surfaces of the tray between the maximum horizontal extension of adjacent teeth, as illustrated in Step A of FIG. 12. Prior to the painting operation the impression material is prepared by mixing 23 parts by weight of powdered alginate (from Coe Laboratories, Inc.) with 54 parts by volume of water. The resulting alignate impression material in an amount of about 22 grams is then deposited in the freshly adhesive painted tray and distributed fairly evenly over the teeth and adhesive painted surfaces except that a slightly excess amount is allowed to remain in the space above the teeth, as illustrated in Step B of FIG. 12. An arch shaped spacer slightly larger than the outline of the tray and prepared by cutting from a commercially available 1/16 inch thick sheet of pure gum rubber is then placed on top of the tray and the resulting assembly inserted into the mouth of the patient, as illustrated in Steps C and D of FIG. 12. After placement in the mouth the dentist applies pressure to again obtain the correct fitting of the tray in the mouth thereby bringing the spacer into contact with the impression material and effecting a fair impression of the upper gum and palate of the patient in the impression material. The tray is allowed to remain in this setting in the mouth with the aid of retaining pressure applied by the patient's tongue for about 3-5 minutes to allow the alginate to set up sufficiently to retain the impression. Upon removal from the mouth the spacer is carefully removed to avoid disturbing the impression and any excess alginate squeezed out during the taking of the impression and overflowing the top of the tray is removed by running a dull knife or wax carver over the top of the tray. With the same knife or wax carver a cut is made in the alginate impression outlining very closely the area not painted with the adhesive and the alignate in the outlined area removed with the same instrument to give a channel in which the top surfaces of the teeth and the unpainted surfaces of the tray between adjacent teeth are exposed. In those areas where the cut is or must be made vertically or where the side walls of the resulting channel otherwise do not flow smoothly into the remaining alginate, the same instrument is run along side walls to incline the same outwardly so that there will be a relatively smooth running in and the desired joining of the side walls with the remaining alginate covering the lower part of the outer and inner walls of the tray. These cutting and smoothing operations as illustrated in Step E of FIG. 12 result in the adapted tray or former provided for use by this invention.

C. The shim comprising a shaped laminate of two layers of DYNEL cloth is then preliminarily placed in the former and the outer uprising wall of the shim trimmed with a scissors if necessary so that the upper edge of the outer shim wall is about 0.03-0.06 inch below the upper edge of the outer wall of the former. The correctly sized shim is removed from the former.

D. The surfaces on both sides of the shim are then lightly painted with the liquid acrylic monomer component of the type to be used in forming the rigid denture-forming material. The purpose of this treatment is to size or fill in between the fibers of the strands of the acrylic fabric of the shim without substantially filling in or blocking the openings in the shim.

E. The liquid and powder components of a cold-curing rigid denture-forming material are then brought together by adding 3.7 cc. of the liquid monomer to 5.2 gms. of the pigmented resin powder and virgorously mixing with a small spoon for about 15 seconds. About one-half of the resulting liquid mixture is poured and distributed evenly over the top of the teeth in the former and the remaining one-half of the material spread evenly over the under or outer surfaces of the palate portion of the shim.

F. The shim is then placed and positioned in the former and pressed down lightly to insure that the denture material in the former is in wetting contact with the under surface of the bottom portion of the gutter section of the shim and to insure that the denture material on the palate portion of the shim is in wetting contact with the entire corresponding surface of the impressed palate portion of the former, such that the denture material now covers all the upper surfaces of the former and adjacent outer surface of the shim except at the upper edge of the outer wall of the former and shim.

G. The liquid and powder components of a cold-curing semi-rigid denture-forming material are then brought together by adding 6.0 cc. of the liquid monomer to 7.75 gms of the pigmented resin powder and vigorously mixing with a small spoon for about 15 seconds. The total of the resulting mixture is disposed onto the shim and distributed over most of the upper or inner surface of the shim except at the upper edge of the outer wall with an appropriately deeper layer or reservoir of denture material in the bottom of the trough of the shim formed by the inner and outer walls and bottom portion thereof.

H. The mouth of the patient is rinsed with cold water and the former then inserted therein. The patient then applies firm but mild pressure by closing of the mouth or by pressing of the tongue against the under surface of the palate portion of the underlying tray of the former. A check is made to determine if the bite is correct. If there is no opposing bite a wax rim or other suitable device may be inserted into the mouth for occlusional bite. Finger pressure is then applied to the front surfaces of the former to force any excess denture-forming material from this area.

I. About 1 to 2 minutes have now elapsed since the former was placed in the mouth and the former is allowed to remain in the mouth for an additional 5-8 minutes with the continued application of firm but mild pressure to the palate portion by the tongue of the patient. At the end of this period the denture-forming material has gelled or hardened sufficiently to take and retain the desired shapes and the former with formed denture therein is removed from the mouth.

J. Excess denture material, if any, may be readily trimmed and/or smoothed off from the formed denture while in the former using a suitable common instrument such as a scissors. The former is separated from the formed denture which may be facilitated by using a dull knife or spatula. Any alginate remaining on the denture is removed by a fast stream of cold water and by wiping with a soft cloth. The separated denture is then washed thoroughly with cold water and inserted into the mouth to check for bite. Desired corrections such as in the bite, if any, may then be made by grinding of appropriate teeth in a conventional manner. The separation between the cast teeth can also be made more pronounced by cutting with a disc, if desired. The denture is then ready for use by the patient.

Various preferred embodiments of the present invention have been described for purposes of illustration only and shall not be taken as having a limiting effect on the scope thereof. In particular, it will be evident that the various improvements provided by the present invention may be realized in general in the in-situ formation of dentures involving methods utilizing a devise or assembly carrying false teeth and having wall means establishing a gum-receiving portion or trough adapted to hold denture-forming material which is curable at mouth temperatures to take the shape of and fit to a patient's gum, including especially devises or assemblies in which inner and outer removable wall portions form the gum-receiving trough and in which the curable denture-forming material functions to join together the resulting artificial gum and the false teeth. It will also be evident that various modifications will be apparent to those skilled in the art and may be made without departing from the scope and spirit of the present invention.

The shims which may be used in practicing the invention are thin articles defined herein as having two opposing surfaces of substantial surface area. For purpose of describing and defining the shims and the surfaces thereof it will be noted that various terms may be used with reference to such respective surfaces such that the surface which faces or will face the denture-forming assembly, tray or former is referred to as the "first" surface, or "outer" surface or "under" surface of the shim while the surface which faces or will face the gum and/or palate of the patient is defined as the "second" surface, or "opposite" surface, of "inner" surface or "upper" surface of the shim.

Claims

What is claimed is:

1. The method of preparing a former for use in forming a denture in-situ in the mouth of a dental patient comprising distributing an impression material on the uprising inner and outer wall of a tray carrying false teeth, said inner and outer walls defining a gum receiving portion having a bottom portion in which the top of the false teeth are exposed; placing a spacer over said impression material; applying pressure to the spacer to obtain an impression of the gum of the patient in the impression material; and exposing the impression material and top of the false teeth to provide a former comprising the tray, impressed outer and inner wall portions of impression material supported respectively by the uprising outer and inner walls of the tray and a channel in which the top of the false teeth are exposed.

2. The method of preparing a former for use in forming a denture in-situ in the mouth of a dental patient comprising distributing an impression material on the uprising inner and outer walls of a tray carrying false teeth, said inner and outer walls defining a gum receiving portion having a bottom portion in which the top of the false teeth are exposed; placing a spacer over said impression material; inserting said tray with impression material therein and spacer over said impression material into the mouth; applying pressure to the spacer in the mouth to obtain an impression of the gum of the patient in the impression material; removing the tray carrying the impressed impression material and spacer from the mouth; and exposing the impression material and top of the false teeth to provide a former comprising the tray, impressed outer and inner wall portions of impression material supported respectively by the uprising outer and inner walls of the tray and a channel in which the top of the false teeth are exposed.

3. A method in accordance with claim 2 in which the outer and inner walls of the tray are interconnected by an integral bottom portion to form a trough having a lower portion in which the false teeth are carried and an upper portion defining the gum-receiving portion.

4. A method in accordance with claim 3 in which impression material is also distributed on the top of the false teeth, in which said impression material on the top of the false teeth is also impressed by the pressure applied to the spacer, and in which the top of the false teeth are exposed by removing said impressed impression material from the top of the false teeth.

5. A method in accordance with claim 3 in which the tops of the false teeth are covered by a space-maker prior to the application of pressure in the mouth and in which the tops of the false teeth are exposed by removing said space-maker.

6. The method of claim 3 in which a former for a lower denture is prepared.

7. A method for preparing a former for an upper denture in accordance with claim 3 in which a palate portion is integral with the inner wall of the tray, in which impression material is also distributed on said palate portion, in which said impression material on said palate portion is also impressed by the pressure applied to the spacer, and in which said former includes an impressed palate portion of impression material supported by the tray palate portion and integral with the impressed inner wall portion.

8. A method in accordance with claim 6 in which impression material is also distributed on the top of the false teeth, in which said impression material on the top of the false teeth is also impressed by the pressure applied to the spacer, and in which the top of the false teeth are exposed by removing said impressed impression material from the top of the false teeth.

9. A method in accordance with claim 7 in which impression material is also distributed on the top of the false teeth, in which said impression material on the top of the false teeth is also impressed by the pressure applied to the spacer, and in which the top of the false teeth are exposed by removing said impressed impression material from the top of the false teeth.

10. The method of preparing a former for use in forming an upper denture in-situ in the mouth of a dental patient comprising distributing an impression material on the uprising inner wall and palate portion of a tray carrying false teeth and having uprising inner and outer walls and a palate portion integral with the inner wall of the tray, said inner and outer walls defining a gun-receiving portion having a bottom portion in which the top of the false teeth are exposed; placing a spacer over said impression material; obtaining an impression of the patient's palate and inside surface of the patient's upper gum by the application of pressure through to the spacer; and exposing the impression material and the top of the false teeth to provide a former comprising the tray and impressed inner wall and impressed palate portion supported respectively by the inner wall and palate portion of the tray.

11. A method in accordance with claim 10 in which the impression of the patient's palate and inside gum surface in the impression material is obtained by the application of pressure through the spacer by the actual palate and upper gum of the patient in the mouth of the patient.

12. A former for forming a denture in-situ in the mouth of a dental patient comprising uprising inner and outer walls forming a gum-receiving portion, false teeth having their tops exposed in the bottom of the gum-receiving portion, impressed uprising inner and outer wall portions of impression material providing an impression of the corresponding surfaces of the gums of the patient at a spaced distance from the gums, said impressed inner and outer wall portions being supported respectively by said first-named inner and outer walls, and a channel having its side walls formed by the lower portions of said impressed wall portions and a bottom comprising said exposed tops of the false teeth.

13. A former in accordance with claim 12 in which the first-named inner and outer uprising walls are interconnected by an integral bottom portion to form a trough having a lower portion in which the false teeth are carried and an upper portion defining the gum-receiving portion.

14. A former in accordance with claim 12 for forming an upper denture, in which a palate portion is integral with said first named inner wall and in which an impressed palate portion providing an impression of the palate of the patient is integral with said impressed inner wall and supported by said first named palate portion.

15. A former for forming an upper denture in-situ in the mouth of a dental patient comprising uprising inner and outer walls and palate portion integral with said inner wall, said inner and outer walls forming a gum-receiving portion, false teeth having their tops exposed in the bottom of the gum-receiving portion, and impressed uprising inner wall and palate portions of impression material providing respectively an impression of the inside surface of the patient's upper gum and patient's palate, each of said respective impressions respectively being at a spaced distance from said surface, said impressed inner wall and palate portion supported respectively by said first named inner wall and said first named palate portion.

16. In a method of forming a denture in-situ in the mouth of a dental patient comprising providing and inserting into the mouth an assembly comprising false teeth and having uprising inner and outer wall portions forming a gum-receiving portion and have curable denture-forming material in at least said gum-receiving portion, and retaining said assembly in the mouth for at least a time to cure said denture-forming material sufficiently to retain the shape of the gum of the patient: the improvement comprising providing the assembly by distributing an impression material on the uprising inner and outer walls of a tray carrying false teeth, said inner and outer walls defining a gum-receiving portion having a bottom portion in which the top of the false teeth are exposed; placing a spacer over said impression material; applying pressure to the spacer to obtain an impression of the gum of the patient in the impression material; and exposing the impression material and top of the false teeth to provide an assembly comprising the tray, impressed outer and inner wall portions of impression material supported respectively by the uprising outer and inner walls of the tray and a channel in which the top of the false teeth are exposed.

17. In a method of forming a denture in-situ in the mouth of a dental patient comprising providing and inserting into the mouth an assembly comprising false teeth and having uprising inner and outer wall portions forming a gum-receiving portion and have curable denture-forming material in at least said gum-receiving portions, and retaining said assembly in the mouth for at least a time to cure said denture-forming material sufficiently to retain the shape of the gum of the patient; the improvement comprising providing the assembly by distributing an impression material on the uprising inner and outer walls of a tray carrying false teeth, said inner and outer walls defining a gum-receiving portion having a bottom portion in which the top of the false teeth are exposed; placing a spacer over said impression material; inserting said tray with impression material therein and spacer over said impression material into the mouth; applying pressure to the spacer in the mouth to obtain an impression of the gum of the patient in the impression material, removing the tray carrying the impressed impression material and spacer from the mouth; and exposing the impression material and top of the false teeth to provide an assembly comprising the tray, impressed outer and inner wall portions of impression material supported respectively by the uprising outer and inner walls of the tray and a channel in which the top of the false teeth are exposed.

18. A method in accordance with claim 17 in which the inner and outer walls of the tray are interconnected by an integral bottom portion to form a trough having a lower portion in which the false teeth are carried and an upper portion defining the gum-receiving portion.

19. A method in accordance with claim 18 in which impression material is also distributed on the top of the false teeth, in which said impression material on the top of the false teeth is also impressed by the pressure applied to the spacer, and in which the top of the false teeth are exposed by removing said impressed impression material from the top of the false teeth.

20. A method in accordance with claim 18 in which the tops of the false teeth are covered by a space-maker prior to the application of pressure in the mouth and in which the tops of the false teeth are exposed be removing said space-maker.

21. The method of claim 19 in which a former for a lower denture is prepared.

22. A method for preparing an upper denture in accordance with claim 19 in which a palate portion is integral with the inner wall of the tray, in which impression material is also distributed on said palate portion, in which said impression material on said palate portion is also impressed by the pressure applied to the spacer, and in which said assembly includes an impressed palate portion of impression material supported by the tray palate portion and integral with the impressed inner wall portion.

23. An in-situ formed denture formed in accordance with the method of claim 17.