NO129934B - - Google Patents

Description

Method of making a

shape template for a denture (dental prosthesis).

The present invention relates to an improvement in the in situ production of a dental prosthesis in the patient's mouth.

US patent document no. 3,460,252 describes a method for creating dental prostheses using a hardenable, stoppable prosthetic material that is stopped in a flexibly arranged prosthetic template in which artificial teeth can be set. The prosthetic template and the stopper are inserted into the patient's mouth. A pressure is applied so that when the plastic hardens in situ, a permanent impression of the palate and the surrounding mouth area is created. The prosthetic template and the plastic material (the prosthesis) are taken out of the patient's mouth and the prosthetic template is torn off and a complete dental prosthesis is then obtained.

In the aforementioned patent document, various methods and devices are described and shown for the aforementioned in-situ production of a denture or a dental prosthesis in the mouth of a patient. Some plastic materials can cause irritation of the sensitive oral tissue and in such cases it is desirable to use a covering (e.g. a thin plastic film) which is able to protect the oral tissue, but which allows reproduction of the shape of the mouth in the plastic material. The use of a "filler" or spacer plate was considered to regulate the thickness of the plastic material forming the palate in an overdenture, but this "filler plate" did not cover the gum part of the prosthesis and formed only part of the surface of the prosthesis.

As a further development of this technique with in-situ formation

of a denture or dental prosthesis in the patient's mouth is suggested, see e.g. the German Offenlegungsschrift 2,105,908,

that one uses an inlay or inlay plate of a relatively stiff and porous material, between layers of hardenable prosthetic material, as this inlay plate is provided with a channel-shaped part which essentially corresponds to the shape of the patient's gums and which fits spaciously into the gum-absorbing part of the prosthetic template that will be used. This inlay plate primarily has the purpose of promoting a uniform distribution of the prosthetic material in the form template used for the manufacture of the prosthesis and as the preferably porous inlay plate in the finished denture is firmly connected to the prosthetic material, a strengthening of the entire construction is achieved at the same time as it becomes possible with a simultaneous application of different prosthetic materials in the upper and lower sides of the denture.

The present invention thus relates to a method for producing a form template for a denture (dental prosthesis), which is an approximately contour-correct impression or reproduction of a patient's gum parts and possibly also the palate parts, for use in an in-situ production of a denture. The distinctive feature of the method according to the invention is that the impression of the aforementioned gum and palate parts is taken in the patient's mouth using a layer of soft impression material which is deposited in a bowl-shaped mold template containing a set of artificial teeth and which has a shape which approximately corresponds to and is large enough to provide space for the denture to be produced, since the impression of the aforementioned gums

and palate parts in the impression material is achieved with the help of a flexible spacer plate or spacer placed between the impression material in the mold template and the aforementioned gum and palate parts, and that pressure is applied to the mold template and the spacer plate after which the spacer plate is removed from contact with the impression material so that it leaves a space which in the subsequent in-situ production of the denture can be filled with stoppable denture-forming material.

In the present invention, a flexible spacer plate or spacer is thus used which does not form any part of the finished dental prosthesis, but is only a temporarily used means to shape the space which is then to be filled with the hardenable, bite-forming material.

These and other features of the invention appear in the patent claims.

The aforementioned template is individually adapted to the patient's mouth,

as the spacer plate provides and at the same time controls the space that is filled by the prosthetic material of stope plastic during the shaping of the dental prosthesis, and then especially in the important areas of the palate and on the inner and outer flanks of the palate. The intermediate plate can be pre-shaped in the shape of a bowl or it can consist of a sheet of material which, under gentle pressure, assumes the shape of the patient's palate. If sheet-shaped material is used, it is preferred to use a material with satisfactory tensile properties so that it roughly corresponds to the shape of the template and the patient's mouth without any significant curling or overlapping. This ensures the transfer of a correctly shaped impression of the mouth to the impression material. It is also preferred that the spacer plate or spacer should be able to adapt to the shape of the patient's mouth without being too compressible, so that

the thickness of the final denture can be more easily maintained and controlled. Suitable spacer plates or spacers can be produced by cutting arc-shaped pieces from a sheet of commercially available, pure natural rubber, e.g. with a uniform thickness of approximately 1.6 mm, or of a sheet of mesh-formed polyethylene foam, e.g. a foam plastic available under the trade name "Minicel L-200" with a uniform thickness of approximately 2.5 - 3.2 mm. Satisfactory results can be obtained using an intermediate plate or spacer of uniform thickness. However, spacer plates of varying thickness can also be used, so that in the final dental prosthesis areas are obtained where a greater or lesser thickness of the prosthesis material is desired. For the creation of an upper denture with a greater thickness in the gum area than in the other areas, it can e.g. an intermediate plate is used which has a greater thickness in the gum area.

The impression material can be any material that can take an impression of the patient's mouth, and which is harmless from a dental point of view. Various such materials are known. An alginate gel that is based on materials that have so far found use as impression materials in dental technology can give very good results. Such alginate gels can normally be prepared by mixing dry alginates and water into a paste of suitable consistency.

The bowl-shaped prosthetic template, which is preferably vacuum-formed or produced by spray-stopping or blow molding of an ethylene or propylene polymer or copolymer, is preferably a thin flexible plastic material roughly shaped like the human gums. A bowl for the production of an upper dental prosthesis preferably comprises a palatal part. In addition to this, it is preferred that artificial teeth are arranged in a U-shaped channel in the prosthetic template. These artificial teeth can be individual teeth or a plurality of tooth sections, or they can be stopped in one piece in the prosthetic template. As the U-shaped channel corresponds to the natural shape of a set of human teeth, these artificial teeth can be well fitted. The teeth can be retained with the help of a binder, e.g. silicone rubber, or by means of friction retention in recesses or markings in the channel in the form template.

The denture template, preferably containing artificial teeth, is prepared in such a way that the impression material is distributed over the inner surfaces of the template to form a layer. Although this layer must only extend so far as to take an impression of the inner and outer sides of the palate, or of the palate and the inside of the palate, it is preferred that the layer also extends over the inner surfaces of the template and the base of the palate which normally wears the teeth. When the template contains a set of artificial teeth,

then the layer preferably extends over the base of the artificial teeth. In the case of an upper denture, the layer covers the palate part of the template to take an impression of the patient's palate. If alginate impression material is used, it is preferred that the inner surfaces of the template are first covered with an adhesive in order to effect or favor an adhesion of the impression material to the inner surface of the template, as well as to prevent the impression material from separating from the template floats after the impression has been made. Suitable adhesives include water-based pressure-sensitive latex-based adhesives, as well as an adhesive commercially available under the trade name "Gel-Grip". It is preferred that all internal surfaces of the template, with the exception of the base for the false teeth, are coated with an adhesive.

The spacer plate or spacer is then placed in the correct place in contact with the layer of impression material and the device is inserted into the patient's mouth and pressure is applied outwards through the spacer plate or spacer by the patient and/or the dentist to produce an impression of the gums in the impression material. Is alginate etc. used material as impression material, the pressure is preferably maintained for approximately 2 to 5 min. to achieve a sufficiently stable impression. The device is then taken out of the mouth and the spacer plate or spacer is carefully removed so that a covering of the impression formed in the impression material is avoided. Surplus impression material, which has flowed over the template, can be easily removed by using a blunt knife or the like. which is lined over the edges of the template. When the impression material covers the base of the false teeth, it is carefully removed using a blunt knife or similar. Instead of covering the base of the teeth with impression material, after which this material is removed, an arc-shaped covering can also be used which has the same or a smaller thickness than the desired thickness of the prosthetic material in the final prosthesis. The cover is brought into contact with the base of the teeth for the layer

of impression material is spread over the rest of the template. After the impression of the patient's palate has been made, the covering is removed, if necessary, together with any impression material that may have flowed over the covering.

The resulting template is individually adapted to the patient's palate and is used for the creation of dental prostheses in situ. In this case, the template carries a layer of hardenable prosthetic material made of plastic, which is inserted into the mouth and takes the shape of the patient's palate. When the denture material is cured, the denture is removed from the template and all impression material adhering to the denture is washed away. The produced template can also be used in the production of prostheses with two layers of prosthetic material, between which there is a thin spacer or insert, at least in the part of the prosthesis that occupies the gums. Usable spacers or inserts for use between two layers of prosthetic material when manufacturing prostheses in situ and a method for manufacturing prostheses in situ using such spacers or inserts are, as previously mentioned, described in the German Offenlegungsschrift No. 2,105,908.

In one embodiment, the template for an overdenture is prepared using a template that only carries a layer of impression material in the palate area and on the inner wall of the U-shaped channel in the template, as this still enables the creation of an individual upper template. The spacer plate or spacer is preferably the full size of the template. Should any impression material be pressed against the base of the artificial teeth, this is removed because the template is used during the actual creation of the prosthesis. However, it is preferred that impression material is spread over essentially the entire inner surface of the template and this method must be described in detail.

In the following, the invention will be illustrated in more detail by means of embodiment examples with reference to the attached drawings, in which: Fig. 1 shows a perspective view of a prosthesis template for an upper prosthesis without teeth. Fig. 2 shows a perspective view of a template for a lower prosthesis with teeth.

Fig. 3 shows a section along the line 3-3 in fig. 2.

Fig. 4 shows a plan view of an upper template with a stopped set of false teeth. Fig. 5 shows a soap in a section along the line 5-5 in fig. 4. Fig. 6 shows an elevation of an upper template with dependent impression material and an intermediate plate or spacer above the impression material, with cut away parts showing the impression material and teeth under the intermediate plate or spacer.

Fig. 7 shows a vertical section along the line 7-7 in fig. 6.

Fig. 8 shows an elevation of an upper template, in which an impression is formed, and from which the impression material covering the teeth has been removed.

Fig. 9 shows a vertical section along the line 9-9 in fig. 8.

Fig. 10 shows a perspective view of a porous dental inlay or insert which is preferably used in connection with a lower template. Fig. 11 is an extended view of an upper template with a plastic layer and a porous interlayer or insert above the template and which is to be placed on the plastic layer. Fig. 12 is a schematic illustration of the procedural steps for using a template for manufacturing the prosthesis. Fig. 13 is a plan view of a finished upper prosthesis containing a template.

Fig. 14 shows a vertical section along the line 14-14 in fig. 13.

Fig. 15 shows a vertical partial section along the line 15-15 in fig. 13. Fig. 16 shows a vertical section through a finished prosthesis after the removal of the template and shows the prosthesis in position for the section 14-14 in fig. 13 after removing the template and impression material from the one in fig. 13 showed compilation. Fig. 17 shows a perspective view of an intermediate plate or spacer for making a lower template.

In fig. 1 to 5, a prosthetic template 20 is shown as preferred

is made of thin, bendable plastic material which is preferably of the type polyethylene or polypropylene or copolymers thereof. The template 20 is used for the production of an upper prosthesis and the template 22 for the production of a lower prosthesis. Templates 20 and 22 have largely the same shape as the arch of the mouth. They have an outer upright flexible wall 24, and an inner upright flexible wall 26 which are connected to each other along the template's bottom piece 29. The upper template has a palate part 28.

The outer wall 24 and the inner wall 26 can together with the bottom part

29 is perceived as a trough-shaped recess 30, the upper part of which has a part 32 for receiving the gums and the lower part is to receive artificial teeth. The part that will accommodate the gums has a base that includes or delimits the raised base parts of the artificial teeth that will then be connected to the prosthesis-forming material. The channel 30 with its lower part is relatively narrow in the front part 36 of the template. Its width increases along the side part 38 of the template, as can be seen in particular from fig. 4. In this way, the teeth are held firmly in the template. In the lower part of the channel 30 on the template 20, markings or cavities 40 are formed, preferably in the form of spaced apart and successively impressed pockets 40, which are preferably continuously connected openly to each other along the arc of the lower part of the gutter. These cavities 40 can be produced by molding or in another suitable way. They show the user the correct position for the artificial teeth 42 inside the template 20 for the manufacture of the prosthesis. Each tooth is thus held firmly in a cavity or pocket 40, and the teeth 42 are further held firmly by the width of the channel 30 gradually becoming larger. The teeth 42 are thus held firmly and cannot easily move from their assigned place. The teeth cannot therefore shift to the side or turn and it is always ensured that they lie flush with each other. The artificial teeth used are arranged inside the pockets 40 and can be arranged as a stbpt unit in one piece with all necessary teeth, as this is illustrated in the figures "or be arranged as a plurality of tooth parts or tooth sections with one or more teeth. They can also all be arranged as individual teeth which are possibly held in place with the help of a binder such as silicone rubber, in the manner described in US patent 3,460,252. Both the upper template 20 and the lower template 22 preferably have an outwardly directed step 41 which is more distinctly formed in the direction of the rear end of the template than at the front end. The step can also be formed more distinctly on the outer wall 24 than on the inner wall 26. The steps 41 provide space for the impression material and they correspond to the natural step-off of the gums from the teeth. When artificial teeth are placed in the pockets 40 without a bonding agent, the steps 41 should be formed more distinctly in order to reproduce the natural stepping of the gums by the teeth, as this is illustrated for example in fig. 3 and 5.

The template 20 with inserted teeth 42 is e.g. shown in fig. 4 and

5. The template can be prepared to enable the creation of the prosthesis by depositing an impression material in the template, the impression material 43 being spread over the inner surfaces of the outer wall 24, the inner wall 26 and the palate part 28, as shown in fig. 6 and 7.

In a preferred embodiment, the base for the teeth 42 is also covered, so that the impression material 43 is essentially distributed over the whole of the front surfaces in the inside of the bowl, as also shown in fig. 6 and 7.

When an impression material such as f.ele. is prepared from alginate, it is desirable that the available inside of the template for the deposition of the material in the template is covered with adhesive to effect or promote adhesion of the material to the inside of the template. This application of a layer of adhesive (which is only shown in Fig. 12) ensures that the impression material does not separate from the stencil floats after the impression is made.

If an adhesive is used, this is preferably applied

the total available inside of the template 20, i.e. the inside of the outer wall, 24, the inside of the inner wall 26 and the inside of the palate part 28, with the exception that the uncovered surfaces of the teeth 42 and the narrow areas of the template between the teeth are not coated or covered with adhesive.

The template 20 with the impression material 43 therein is thus ready for insertion into the patient's mouth, after a spacer plate or spacer 44 has been arranged in a suitable position in relation to the template, so that the impression of the palate can be obtained by applying pressure on and through the spacer plate or spacer 44. The main purpose of the spacer plate or spacer 44 is that it roughly indicates and occupies the space that is then taken up by the plastic material forming the prosthesis, at least in the more critical areas that lie next to the outer wall 24 and the inner wall 26.

The intermediate plate or spacer 44 is placed in a suitable position over the impression material 43, e.g. in the template 20, as illustrated in fig. 12, and the device thus obtained is inserted into the mouth, as is also apparent from fig. 12. A gentle pressure is then applied using the spacer plate or the spacer 44 by the patient and/or the dentist to make an impression of the upper gums and the palate in the impression material.

The template with the impression formed therein is removed from the mouth. Is alginate etc. used material the device must be kept in

mouth under pressure for about 2 to 5 min. for it is removed,

so that the impression material can harden sufficiently and is sufficiently hardened in the subsequent method steps.

After the template has been removed from the mouth with the impression formed therein, the spacer plate or spacer is carefully removed to prevent the impression from being left in the impression material. Excess impression material, which has been pressed out over the template, can be easily removed by using a blunt knife that is drawn over the edges of the template. The impression material also covers the teeth 42 after the impression has been made and is also removed therefrom by suitable means, e.g. also using a blunt knife to form an arcuate channel 45 which exposes all base surfaces of the teeth 42 and also those surfaces of the template 20 located between the largest horizontal extents of neighboring teeth, as shown in Fig. 8. The side walls 46 of the channel 45 are preferably smoothed or otherwise treated so that they lean outwards from the bottom of the canal, which is formed by the surfaces of the teeth, so that the transition between the upper side of the edges of the teeth and the plastic prosthetic material thereby has the most natural appearance possible, as partially shown in fig. 9. The manufactured assembly, which is illustrated in fig. 8 and 9, constitute a form-fitting upper template 50, which is specially adapted to the individual patient. It is also adapted so that the desired thickness of the denture can be more or less controlled. The upper template unit 50, as shown in fig. 8 and 9, the template itself 20 therefore comprises an upstanding outer, impressed wall 54 of impression material, which is supported by and/or connected to the upstanding outer wall 24, an upstanding inner, impressed wall 56 of impression material, which is supported by and/or or is connected to the raised inner wall 26, an impressed palatal portion 58 of impression material that is connected to and/or supported by the palatal portion 28 of the template, and a channel 45 that exposes the teeth 42 carried by the template 20. A not illustrated lower template unit for production of a lower denture can be produced in an analogous way. This lower template unit will therefore have a lower template 22, an upstanding impressed wall of impression material which is supported by and/or connected to the outer wall 24 of the lower template, an upstanding inner impressed wall of impression material which is supported by and/or is connected to the inner wall 26 of the lower template and a channel 45 which exposes the teeth 42 carried by the lower template 22. Fig. 17 illustrates an intermediate plate or spacer 44a for making a lower template.

In the preferred method for producing a as i

the previously described template, the impression material covers the tops of the teeth while the impression is being taken and is then removed to form a channel 45 in which the base portions of the teeth are exposed.

It should be noted that other methods can also be used for

to produce a template with the desired channel 45 which exposes the teeth. E.g. an arc-shaped spacer plate or spacer, not shown, which generally has the shape and width of the desired arc-shaped and U-shaped channel 45 and a thickness less than or approximately equal to the desired thickness of the prosthesis-forming material in this area, can be arranged over the teeth for the deposition of the impression material . This spacer plate or spacer can later be removed together with any impression material that may adhere to it, after the impression has been taken, whereby the desired channel 45 is formed in which the teeth and the surfaces of the template between the maximum horizontal extents of neighboring teeth are exposed.

The finished template unit 50 with the template 20 itself and the impression created therein as well as with the channel 45, which exposes the upper side of the teeth 42, is now ready to receive the gum-forming prosthetic material in the final stage, which leads to the finished prosthesis. This completion can be carried out as described in US patent document no. 3,460,252, as prosthesis-forming or

hardenable prosthetic material is deposited in the template and distributed over the exposed surfaces of the teeth 42 as well as the intermediate exposed parts of the template 20 and over the surfaces of the impressed walls of impression material 54 and 56 and the impressed palatal part 58 of impression material. If desired, a palate can be used

spacers or inserts (not shown) which at least cover the largest part of the palate part to control the thickness of the palate part during the formation of the prosthesis and its completion, as described in US patent document 3,460,252. The resulting device contains the template unit 50 with prosthesis-forming material arranged therein. This device is then inserted into the patient's mouth where the prosthesis-forming material is quickly hardened to at least reproduce the shape of the gums. After removal from the mouth, the template unit 50 can be cut using a blunt knife or the like. easily separated from the prosthesis by removing the template itself 20. The removal of the template simultaneously removes a significant part of the impression material. If impression material remains on the formed prosthesis, this can be removed in an appropriate manner. Used e.g. alginate secretes the impression material after forming the prosthesis while it is still moist, so that it can be removed by rinsing with water and wiping with a soft cloth.

The dental prosthesis can also, as previously mentioned, be produced by using a dental spacer or inlay with a gutter-shaped gum material inside the prosthesis material itself, and then preferably in connection with different types of prosthesis-forming materials. The structures used here respectively the resulting devices are shown in fig. 10, 11, 13, 14, 15 and 16. The channel-shaped, flexible insert or insert can be a separate part, such as e.g. the arc-shaped insert or insert 59 in fig. 10, which is preferably used together with the lower template when producing a lower prosthesis, but which can also be used with an upper template 50, or the intermediate layer or insert can be a channel-shaped part 62 in an intermediate layer or insert 60 in one piece with a palatal part, as shown in Fig. 11 for use with the upper template unit 50 in the manufacture of an upper prosthesis. A separate spacer or insert of the type such as the spacer or insert 59 can be used alone or in connection with a separate, not illustrated palatal overlay or palatal insert when creating an upper dental prosthesis. However, it is preferred to use the complete spacer or insert 60 when manufacturing the upper prosthesis. The preferred complete upper insert 60 or insert generally comprises a palate part 61 and a channel-shaped part 62 in one and the same piece. The gutter part 62 comprises a bottom part 63 and in one and the same piece with an upright wall part 64 and an inner upright wall part 65 which forms an interfolding gutter which can accommodate the prosthesis-forming material and the gums themselves on

the patient. As fig. 10 shows, the intermediate layer or insert 59 also includes the outer upright wall 64, the inner upright wall 65 and a bottom part 63 in one and the same piece with the outer and inner wall, whereby a channel is formed which can accommodate the prosthesis-forming material and • the gums themselves . The intermediate layer or insert 59 or the gutter part 52 in the intermediate layer or insert is constructed in such a way that it can be inserted into the gum receiving part 32 in the upper part of the recess 30 on the template unit 50 with a spacious fit. The spacers or inlays are therefore preferably shaped so that the shape and contour of the spacers or inlays conform to the shape of the template, and then including the palate part in the case of an upper template, taking into account in each case that the spacer or inlay must be placed on a first layer of prosthetic material that is inserted into the template. However, it is not necessary that the upright wall part 64 in the complete upper intermediate layer or insert 60 or the upright wall part in the intermediate layer or insert 59 are exactly parallel to the corresponding parts of the templates used in the individual case, as the preferred intermediate layers or inserts are flexible and deviations from the optimal conditions can be corrected with the help of the gum-forming prosthetic material, which joins the opposite sides of these spacers or inlays when the prosthesis is formed in the patient's mouth. The spacers or inserts 59 and 60 can be made of different materials, such as e.g. textile materials, but also of solid, non-porous material, as described in e.g. the German Offenlegungsschrift 2,105,908. It is usually preferred that the intermediate layer or inlay be made of sufficient polyacrylic-based material to ensure a complete connection with the prosthesis-forming acrylic material. It is also preferred that the spacers or inlays are pigmented or colored in some other way with skin color or color like natural gums to make the prosthesis invisible.

The spacers or inserts are usually approximately 0.5 - 3 mm thick and preferably approximately between 0.5 and 1.8 mm thick. In order to

to avoid misunderstandings, it is mentioned here that the aforementioned spacers or inserts 59 - 65 serve as inserts in the prosthesis itself and must not be confused with the spacer plates or spacers 44 and 44a which have a completely different and essential function in the method according to the invention.

In a method for producing an upper prosthesis, which

shown in fig. 11, 13, 14, 15 and 16 using a complete upper spacer or insert 60, a first layer of prosthetic material 66 is placed in the upper part of the channel 30, in the channel 45, over the teeth 42 and over the rest of the free surface of the impressed walls 54 and 56 of impression material and the impressed palatal part 58 of impression material. The complete upper intermediate layer or insert 60 is then placed in the correct position on the first layer of prosthetic material 66, and then preferably so that the prosthetic material 66 is in wetting contact with the entire underside of the intermediate layer or insert 60, with the exception that the upper end part of the standing wall part 64 can remain free of prosthetic material. Alternatively and preferably, the prosthetic material in the first layer in the palatal area can be applied directly to the underside of the palatal part of the intermediate layer or insert for the intermediate layer or insert to be brought into contact with the template.

Another layer of gum-forming or prosthetic material 67 is applied

then on the upper, uncovered upper side of the intermediate layer or insert 60, above the free upper side of the intermediate layer or insert 60

which lies directly above the teeth. The material is then spread or applied so that the total exposed surfaces of the intermediate layer 60 including the palate part are covered, but with the exception of the edge part or the horizontal edge part of the standing wall 64

on the intermediate layer or inlay 60, as these parts are later covered and surrounded by prosthetic material which flows under the application of the pressure exerted during the formation of the prosthesis. When the prosthetic material is spread over all relevant surfaces, the volume ratio between the prosthetic material 66 in the first layer and the prosthetic material 67 in the second layer is preferably in the range from 1:3 to 1:1. A ratio of about 2:3 is preferred.

The manufacture of the prosthesis-forming assembly using an intermediate layer or insert 59 for forming a lower prosthesis in connection with a lower template is carried out in an analogous way and then using two layers of dental material, otherwise as described above. The assembly that emerges to form an upper or lower prosthesis using an upper spacer or insert 60 or a lower spacer or insert 59 is thus ready to be inserted into the patient's mouth, after which the prosthesis is formed in the manner described above.

The gum-forming prosthetic material is a suitable, cold-setting pigmented mixture of a powder and a liquid. The powder is a polymer, and then preferably of the acrylic type. Certain acrylic copolymers containing vinyl or styrene components can also be used. The liquid material is preferably an acrylic monomer or a mixture of acrylic monomers, e.g. methyl methacrylate and butyl methacrylate.

These materials are known and are already used, e.g. as materials for the repair of prostheses. The powder and/or liquid contain small amounts of known catalysts which, in the course of a short time without an additional heat source, cause the mixture to harden. The prosthetic material can be a so-called "rigid" prosthetic material or more flexible, "semi-rigid" prosthetic material. These materials and other, less rigid materials are known in dental technology. Resins that harden in the cold and that are used in dentistry often cause discomfort during the hardening in contact with the patient's gums, mainly because of a stinging sensation that the patient may have. Contact between the hardenable resin and the patient's gums can be avoided by enclosing the device that forms the prosthesis in a thin casing, as described in US patent 3,460,252. However, the use of such a protective covering becomes necessary when prosthetic materials are chosen that are more suitable for direct contact with the gums without causing a harmful effect. One such more rigid material is in the trade under the name "Truliner" and another such material under the trade name "Duraliner". A more suitable, semi-rigid material is in the trade under the name "Soft-Line". Components for other more suitable and preferred semi-rigid materials can be prepared by mixing in a ratio of 10.3 g of the powdered component and 8.0 ml of a liquid component. The powdered component in the commercial product is designated as component 3-A and the liquid component is designated as component 2-A.

The rigid as well as the semi-rigid prosthetic material can, in connection with certain advantages, be used for the in situ shaping of a prosthesis in the mouth of a patient. As can be seen in particular from fig. 11, 13, 14, 15 and 16, the first layer of prosthetic material 66 can be rigid prosthetic material, while the second layer of prosthetic material 67 is a semi-rigid prosthetic material. As shown in particular in fig. 16, the use of these types of prosthetic material makes it possible to produce a final product prosthesis 68, where the outside of the prosthesis including the gum part and the palate part, which are normally exposed to saliva, food, smoke etc., can be made of rigid material, as well as the artificial teeth , which is connected to the formed prosthesis by means of such a material, while the inner, covered surfaces of the prosthesis in direct contact with the gums and palate are formed by a semi-rigid material. The use of the semi-rigid prosthetic material 67 is advantageous for in situ formation of a prosthesis, as this material can be adapted very well and correspond to the gums of the patient, so that no difficulties arise during use. Removing and reinserting the prosthesis is also relatively easy. The use of a semi-rigid prosthetic material 67 is likewise highly desirable, when the patient's palate has unusual protruding areas or depressions, which usually give rise to difficulties when a rigid material is used when forming a prosthesis in situ. On the other hand, the outer or uncovered surface consists of the one in fig. 16 showed a prosthesis made of a rigid material, which has the known advantages of a rigid prosthetic material, including resistance to pitting, loss of shape, stains, discoloration, etc. A lower prosthesis, not shown, can be produced in a similar manner using the combination of rigid and semi-rigid prosthetic material. It should be mentioned that the use of an intermediate layer or insert 59 or a complete intermediate layer or insert 60 facilitates and improves the formation of a prosthesis when using different prosthetic materials, i.e. when using both rigid as well as semi-rigid prosthetic material.

In dental technology, the difference between rigid dental material and other materials, which are less rigid and therefore more exposed and materials which are here described as semi-rigid, is known from the past. For definition, semi-rigid materials are divided into two subclasses, which are designated as "semi-hard" or "soft" dental materials. For descriptive purposes, a suitable distinction can be made according to the commonly used three-point bending test which appears in "INTERIM FEDERAL SPECIFICATION W-R-00179a (DSA-DM)

of 20 February 1967, after which hard prosthetic material has a maximum deflection (deflection) that does not exceed approximately 1.7 mm, while this deflection in accordance with the standard test occurs under an initial load of 1500 g rising to a maximum of 2500 g. Semi-hard prosthetic material has a sag that exceeds 1.7 mm. Semi-hard materials are further defined as having a deflection in the range of 1.7 - 4.0 mm, while deflections above 4.0 mm indicate soft materials. Rigid material has a deflection of between approximately 1.0 to

1.5 mm, while the preferred semi-hard material has a sag between approximately 1.8 and 3.5 mm. "Semi-hard" materials are preferred for use in conjunction with a "rigid" material when forming a prosthesis as described herein.

The combined advantages which the present invention provides in the formation of a prosthesis in situ include that only a smaller number of templates need to be provided for the sizes that are eventually needed. Furthermore, a customized template can correspond to the arch of the mouth and the palate of the patient very accurately and evenly. Furthermore, a prosthesis can be produced where the outsides of the gum part mimic the contour of the natural outsides of the patient's gums. Furthermore, the need for prosthetic

material that is included is determined in advance quite carefully, and consequently also the amount and thickness of the plastic material of the prosthesis in the final prosthesis. Furthermore, considerably less gum-forming material is usually required when producing an in situ formed one

prosthesis. Finally, the manufacture and shaping of a prosthesis in situ according to the invention takes place in accordance with the usual technique of manufacturing dental prostheses with regard to the various aspects.

In the following, a method for creating an upper prosthesis is illustrated step by step in accordance with a preferred embodiment, with particular reference being made to fig.

12 with steps A, B, C, D and E in this figure.

A. A denture template of approximately the correct size, containing a stopped set of acrylic plastic teeth in the desired or correct color, is selected to provide the assembly shown in fig. 3 and in step A in fig. 12. This assembly is placed in the patient's mouth to determine the correct fit and adjustment of the template as well as necessary adjustments. The vertical fit of the template is determined by determining the desired distance that allows prosthetic material to lie between the teeth in the template and the lower edge of the palate at the front of the mouth, and thereby determining to what extent, if at all, the upper part of the the outer standing wall of the template must be cut to or trimmed to achieve this distance during shaping. Any excess parts of the wall of the plastic template are then trimmed away or removed with a knife. The lateral extent of the template is determined taking into account the rear part of the template, whereby the gums are brought into the part of the template that occupies the gums and it is then determined whether the template in question is too wide or too narrow, whereby it is taken into account that both the impression and the prosthetic material in the template will also be present as an addition to the patient's gums. When a lateral correction is necessary, another template with approximately the correct lateral size is selected and adjusted vertically.

B. The impression material is prepared by mixing 23% by weight of alginate powder with 54 parts by weight of water. The insides of the raised external and internal walls and the palatal part of the template are then provided with a thin coating of "Gel-Grip" (an adhesive), whereby care must be taken that no adhesive gets on the teeth or on the exposed surfaces of the template between the maximum horizontal extent of adjacent teeth, as illustrated in step A in fig. 12. The alginate impression material is then applied in an amount of approximately 22 g for a short time beforehand with an adhesive-brushed template and distributed fairly uniformly over the teeth and the adhesive-coated surfaces, with the exception of a somewhat larger proportion remaining in the space above the teeth, as shown in step B in fig. 12. An arc-shaped spacer plate or spacer, which is somewhat larger than the outer contour of the template, is then placed after cutting from a commercially available sheet of pure rubber on the upper side of the template, and the resulting assembly is inserted into the mouth,

as shown in steps C and D in fig. 12. The commercially available rubber sheet is approximately 1.6 mm thick. Next, the dentist applies pressure to obtain a correct fit of the template in the mouth, whereby the spacer plate or spacer is brought into contact with the impression material and an impression of the upper gum and palate area of the patient is obtained in the impression material. The template remains in this state in the mouth by means of a holding pressure applied over the patient's tongue for 3 to 5 min., whereby the alginate hardens or hardens sufficiently to

could record the impression. After removing the mouth, the spacer plate or spacer is carefully removed to avoid

a destruction of the imprint. Any excess alginate, which was pressed out during the impression taking and has flowed over the upper side of the template, is removed with the help of a blunt knife or a knife for cutting wax sections, as the tool is pulled over the upper side of the template. With the same tool, a cut is made in the alginate impression that very precisely indicates the contours of the surface reinforced with adhesive, and the alginate within this surface is removed with the same tool to create a channel in which the tooth bases and the unreinforced surfaces of the template between neighboring teeth can be exposed. In the areas where a cut exists or must be constructed vertically, or where the side walls of the channel that is formed on the other side do not smoothly transition into the remaining alginate, the same tool is lined along these side walls to make them heal outwards, as that it

becomes a relatively smooth transition as well as a desired connection of the side walls with the remaining alginate that covers the lower part of the outer and inner walls of the template. This cutting and smoothing is illustrated in step E in fig. 12. A customized template is obtained which is illustrated in fig. 9. C. A porous interlayer or insert of a shaped laminate of two layers of "DYNEL" fabric is then tentatively placed carefully into the template and the outer, upstanding wall of the interlayer or insert is leveled with a knife if necessary, so that it the upper edge of the outer intermediate wall or insert wall lies 0.7 5 to 1.5 mm below the upper edge of the outer wall of the template. The spacer or insert of the correct size is then removed from the template. D. The surfaces on both sides of the porous interlayer or insert are then carefully coated with a liquid acrylic monomer of the type used when forming in the cold or at room temperature hardening, rigid, prosthesis-forming material. This serves to fill the space between the fibers in the acrylic fabric of the intermediate layer or insert, without the openings in the intermediate layer or insert being particularly filled or blocked.

E. The liquid components and the powder components of the unaffected heat-setting, rigid prosthesis-forming material are then brought together by adding 3.7 ml of a liquid monomer with 5.2 g of the pigmented plastic powder and mixed vigorously with a small spoon for 15 sec. Approximately half of the obtained paste-shaped mixture is poured out and distributed evenly over the tooth bases in the template. The remaining half of the material is distributed evenly over the inner or outer surfaces of the palate part of the spacer or inlay.

F. The shim or inlay is then placed in the template and straightened and gently pressed down to ensure that the prosthetic material in the template comes into moist contact with the underside of the bottom portion of the trough-shaped portion of the shim or inlay, thereby ensuring that the prosthetic material in the palatal portion of the shim or the insert is in moist contact with the overall corresponding surface of the impressed palatal part of the template, so that the prosthetic material now covers all upper surfaces of the template and adjacent outer surfaces of the spacer or insert with the exception of the upper edge of the outer wall of the template and spacer or the post.

G. The liquid and powdery components of a semi-rigid prosthesis-forming material that hardens at room temperature are then brought together by mixing 6.0 ml of the liquid monomer vigorously with 7.75 g of the pigmented plastic powder, and then with a small spoon for 15 sec. The entire mixture obtained is poured onto the spacer or insert and distributed over the greater part of the upper or inner surface of the spacer or insert with the exception of the upper edge of the outer wall and with a suitable deeper layer or reservoir of prosthetic material at the bottom thereof channel-shaped recess on the interlayer or insert formed by the inner and outer walls and the bottom of the interlayer or insert.

H. The mouth is now rinsed with cold water and the template is then inserted. The patient now presses softly and constantly by closing the mouth or by pressing the tongue against the underside of the palate on the underlying template. It is checked to ensure that the bite is correct. If no false bite occurs, a wax disc or other suitable disc material is inserted into the mouth for occlusion bite. The front surfaces of the template are then pressed with the finger to press away any excess prosthesis-forming material from this area.

I. 1 to 2 minutes have now passed. after the template was inserted

in the mouth. The template remains in the mouth for another 5 to 8 minutes. while continuing to practice constant but gentle pressure on the palate using the patient's tongue. At the end of this time, the prosthesis-forming material has gelled or sufficiently hardened to assume the desired shape and retain it. The template with

the prosthesis created therein is then removed from the mouth.

J. Excess denture material, if it occurs at all, can be leveled and/or smoothed away from the formed denture while it is in the template, and then using a suitable tool, e.g. a pair of scissors. The template is separated from the formed prosthesis and this separation can be facilitated by using a blunt knife or a spatula. The alginate that remains on the prosthesis is removed by rinsing with cold water and by rubbing with a soft cloth. The detached prosthesis is then washed carefully with cold water and inserted into the mouth to check the bite. Desired corrections, e.g.

in the bite, if such are necessary at all, they can then be carried out by grinding the teeth in question in the usual way. The separation between stopped teeth can also be made more marked by cutting with a grinding wheel, if this is desired. The prosthesis is then ready for use by the patient.

Claims (3)

1. Method for producing a form template for a denture (dental prosthesis), which is an approximately contour-correct impression or reproduction of a patient's gum parts and possibly also the palate parts, for use in an in situ production of a denture, characterized in that the impression of the aforementioned gum and palate parts are taken in the patient's mouth using a layer of soft impression material (43) which is deposited in a bowl-shaped mold template (20; 22) containing a set of artificial teeth, (42) and which has a shape that roughly corresponds to and is large enough to provide space for the denture to be produced, as the impression of the aforementioned gum and palate parts in the impression material (43) is obtained with the help of a flexible intermediate plate or spacer (44; 44a) placed between the impression material (43) in the form template (20; 22) and the aforementioned gum and palate parts, and that pressure is applied to the form template and the intermediate plate (44; 44a), after which the intermediate plate is removed from contact with the impression material so that it leaves ater a space which in the subsequent in situ preparation of the denture can be filled with stoppable denture forming material (66, 67). 2. Method as stated in claim 1, characterized in that the intermediate plate (44, 44a) is produced from a sheet of natural rubber or foamed polyethylene. 3. Method as specified in claim 1 or 2, characterized in that the impression material (43) is also deposited over the attachment bases for the artificial teeth (42) and that the impression material deposited in these places is removed after the impression of the aforementioned gum and palate parts is taken.