Method for producing artificial denture
BACKGROUND OF THE INVENTION 
     Prior art dentures, such as those disclosed in U.S. Pat. No. 3,839,796, have been successfully produced and fitted to patients and have been very satisfactory but have included an intermediate soft deflectable layer of material between a hard U-shaped base structure and a hard liner; such soft deflectable layers have, in some instances, required a substantial amount of time to cure and become as hard as the original hard U-shaped base structure to which the assembly of teeth is affixed. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method of producing a denture partially in accordance with teachings of U.S. Pat. No. 3,839,796, but not limited thereto, and additionally, the invention comprises method steps, wherein first and second impression models are cast against the tooth and relative gum supporting sides of a denture module, whereupon the soft deflectable layer along with the attached impression material comprised of hard or soft liner material may then be stripped away from the tooth bearing hard U-shaped base assembly of the denture module so that a resin for a hard or soft plastic material may be cast between the hard U-shaped base of the denture module remaining imbedded in one impression model, while both impression models are held in a flask and compressed together, in the usual manner of flasking, so that the base of the final denture produced consists of all hard or soft materials such as hard or soft acrylic material in comparison to the hardness of the original hard U-shaped base of the aforementioned denture module, and this entire hard or soft plastic material such as acrylic is thus intimately impression contoured to the edentulous gum supporting areas of an individual human patient. Specifically, the method includes the step of producing a denture module suitable for recording the intimate contours of an individual human oral cavity and gum supporting areas, and suitable also for casting impression moulds capable of reproducing said individual intimate human oral contours; said denture module may consist of a hard U-shaped base assembly with or without metal, plastic, or wax, reinforcement materials or devices, and a soft deflectably formable layer attached permanently or temporarily thereto, either with or without plastic, metal, or wax reinforcing materials or devices, then deflectably with digital pressure, forming the soft layer to the edentulous gum area of the patient&#39;s mouth; then removing said denture module and placing impression material or hard or soft liner material on the soft deflectably formable layer so as to impression form said material in a consistency adequate to conform intimately to the details of the human mouth and allowing the impression material or hard or soft liner material to substantially cure in the patient&#39;s mouth to thereby provide a cured liner in bonded relation to the soft deflectably formed layer. The fitted module is then used to form a pair of impression models which fit intimately to the contours of the upper and lower surfaces of the fitted denture module; the the cured impression material or hard or soft liner material, along with the soft deflectably formed layer are stripped away from the hard U-shaped base assembly of the denture module, while the hard U-shaped base assembly still retained in one of the impression models and the other impression model is then positioned above the U-shaped base assembly of the denture module, allowing new hardenable denture base resin to be inserted between the hard U-shaped base assembly and the uppermost impression model so as to cast and bond a hard gum conforming structure unitarily to the hard U-shaped base assembly remaining from the denture module, whereby conformity to the intimate detail of the individual human mouth originally impression formed is achieved adjacent to said uppermost impression model. 
     Specifically, the invention comprises the use of various means for removably connecting the soft deflectably formed layer to the hard base and assembly of teeth such that the deflectably formable layer may be readily stripped away from the hard base during the final dental moulding of the denture being produced. The means for removeably connecting the deflectably formable layer to the hard base comprises such elements as snap in portions of the deflectably formable layer which snap into the hard base, or this structure may be disposed in reverse where a portion of the hard base is engaged in the deflectably formable layer. Additionally, wax or adhesive, such as rubber cement or the like, may be used between the deflectably formable layer and the hard base so as to provide a removeable connection therebetween. Also, screws may be used to connect the deflectably formable layer with the hard base, all of which may readily be removed to allow stripping of the deflectably formable layer from the hard base during the moulding operations to produce the final denture in accordance with the invention. 
     An additional modification of the invention relates to a method wherein the assembly of teeth are all cast integral with each other or connected together by a generally U-shaped metal member, such as disclosed in the Huey U.S. Pat. No. 3,727,309 and wherein interlocking portions or projections from the teeth are interlocked with a soft liner material which is capable of being deflectably formably fitted to the edentulous areas of a patient&#39;s mouth. The modification thus obviates the necessity of casting the teeth in a hard base and thus provides for removeable connection of the deflectably formable layer from the assembly of teeth such that in the final casting operation the final impression conformng moulded part is cast directly upon the assembly of teeth. 
     Accordingly, it is an object of the present invention to provide an improved denture wherein a hard U-shaped assembly of prosthetic teeth are bounded to a denture base material whereupon the individually impressioned upper surface of the finished denture, or the portion which comes into intimate contact with the muscosa, is of exactly the same material as the under surfaces but which may or may not be of the same durometer hardness as the U-shaped assembly of prosthetic teeth to which said base is unitarily bonded utilizing methods and techniques pursuant to those methods and techniques as set forth herein. 
     Another object of the invention is to provide a method by which very accurately fitting, individually fitted, dentures may be constructed of materials individually suitable to an individual patient, and in a substantially economical manner. 
     Additional objects of the invention are to provide greater logistical latitude in the utilization of dentists time, whereby such efficient use of time would result in economical advantages to patients without sacrificing the quality of dentistry obtained. Objectively, utilization of the methods and techniques cited herein would provide a fast and efficient means by which a dentist would provide custom dentures to individual patients in either the usual manner, or as a chair side delivery in one day, thus providing high quality, accurately fitting, durable dentures economically. 
     An additional object of the invention is to provide a variety of specific means for removeably connecting the deflectably formable layer relative to the hard base of the invention; the specific means comprising rubber cement, mechanical interlocking mechanisms, as well as screws or the like. 
     Another object of the invention is to provide a modification wherein the foregoing objects are attained while the deflectably formable layer is initially removeably connected directly to the assembly of teeth and is stripped away therefrom previous to the final moulding operation for producing the denture of the invention. 
     Further objects and advantages of the invention may be apparent from the following specification, appended claims and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view similar to FIG. 14 of U.S. Pat. No. 3,839,796 and showing a denture similar to that disclosed therein; FIG. 1 including the same reference characters as may be found in FIG. 14 of U.S. Pat. No. 3,389,796; 
     FIG. 2 is a sectional view of a dental flask with impression models cast into conformity with upper and lower surfaces of a denture module according to the present invention and as shown in FIG. 1 and showing said fitted denture module therein; 
     FIG. 3 is a sectional view similar to FIG. 2 but showing the upper impression model removed and the impression material or hard or soft liner material, along with the soft deflectable layer, stripped away from the fitted denture module, thus leaving the hard U-shaped assembly of prosthetic teeth in the lowermost impression model held in a dental flask; 
     FIG. 4 is a sectional view similar to FIG. 2 showing curable denture base resin cast against the remaining hard U-shaped base assembly of the denture module held in the lowermost impression model and using the upper impression model to transfer the edentulous area surface detail to the upper surface of the curable denture base resin cast and bonded to the hard U-shaped base assembly of the finished denture and showing a cover with a means for forcing the cover tight to compress the impression models together for compressibly bonding the hard plastic denture base material to the remaining hard U-shaped base assembly of the original denture module; and 
     FIG. 5 is a modification of the invention showing rubber cement or the like interconnecting the deflectably formable layer of the denture module and its respective hard base; 
     FIG. 6 is another sectional view showing a portion of the deflectably formable layer interlock into a socket into the hard base of the denture module so as to provide removeable connection and stripping facilities for allowing the deflectably formable layer to be readily stripped and removed from the hard base; 
     FIG. 7 is an enlarged fragmentary sectional view of the structure shown in FIG. 6 showing such structure in greater detail; 
     FIG. 8 is a fragmentary sectional view similar to FIG. 7 and showing screws interconnecting the soft deflectable layer and the hard base so as to provide for removal of the screws and very simple stripping or removal of the soft liner from the hard base during the process of producing the final denture; 
     FIG. 9 is a fragmentary sectional view similar to FIG. 2 but showing a modification of the denture module and moulding operation; 
     FIG. 10 is a view similar to FIG. 3 and relating to the stripping of the soft deflectably formable layer directly away from the assembly of prosthetic teeth while in the mould; 
     FIG. 11 is a fragmentary sectional view similar to FIG. 4 and showing the final moulding operation comprising the casting of a hard patient fitting layer directly onto the assembly of prosthetic teeth in the mould; and 
     FIG. 12 is an enlarged fragmentary sectional view showing the finished denture structure wherein a generally U-shaped metal member is disclosed on an enlarged scale and this member extending through the generally U-shaped assembly of teeth for holding them together. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, a denture such as disclosed in U.S. Pat. No. 3,389,796 is shown and the same reference characters and leader lines as contained in said patent are included in FIG. 1 of the drawings. In accordance with the present invention, the denture shown in FIG. 1 is referred to as fitted denture module. 
     This denture module is produced in accordance with the teachings of said patent. The prosthetic teeth 74 are of hard acrylic, porcelain, silicone, or any other such suitable material, and this assembly is generally a unitary assembly held in position by plastic, metal, or wax devices or other such materials, while a hard base 76 is permanently or temporarily bonded to said assembly of teeth, the hard base 76 and teeth 74 compose a hard base assembly. This hard U-shaped base 76 is provided with a recess 78 in which a soft deflectably formable layer, with or without plastic, metal, or wax reinforcement devices attached thereto, of plastic designated 82 is bonded and this soft deflectably formable layer 88 is impression formed, with finger pressure, in an individual patient&#39;s mouth whereupon it is subsequently removed and a curable impression material or hard or soft liner material layer 90 is placed on the digitally formed soft layer 82 and reinserted into the patient&#39;s mouth so that impression forming of the impressionable liner material may take place in such a manner that the impressionable material sets up or cures in the patient&#39;s mouth to a very accurate fitting detail of the edentulous gum area. Then the denture is removed and is as shown in FIG. 1 of the drawings. 
     Subsequently, an impression model designated 100 in FIG. 2 is cast around the lower areas of the fitted denture module including the prosthetic teeth 74 and then the denture together with the impression model 100 is placed in a flask 102 and plaster 104 is poured in the flask around the impression model 100 up to a level 106 which subsequently forms a parting line for the impression model 100 and secondary impression model 108 as will hereinafter be described. 
     The impression model 100 and the plaster 104 as well as the impression model 108 are of a gypsum or plastic like material with or without metallic fillers, which may be mixed and then hardened into what is commonly known as dental stone or may be recognized as the usual mould material employed for investment casting of metals or the like. 
     After the plaster 104 has set up at its parting line surface 106, the upper parting line surface 106 and upper surface of the cured impressionable materal liner 90 is coated with a conventional release agent and then the plaster or dental stone 108 is poured into the flask 102 over the denture and the surface 106 and the stone 108 is allowed to harden so that detail of the cured impression formed liner 90 of the denture module of FIG. 1, is transferred to the lower surface of the impression model 108 to match that originally produced on the denture module as shown in FIG. 1 by curing said impressionable material in the individual patient&#39;s mouth. 
     After the impression model 108 is finished and hardened, it is separated at the parting line 106 from the plaster 104 and from the upper surface of the cured liner 90, whereupon the cured liner 90 and the soft deflectable layer 82 bonded thereto, may be stripped away from the hard U-shaped base assembly 76 leaving only the hard U-shaped base assembly 76 and the prosthetic teeth 74 in the impression model 100 surrounded by the hard plaster or dental stone 104. Then the U-shaped hard base assembly 76 is cleaned and exposed together with the upper surface 100 of the impression model 100 which was originally cast adjacent to the lower surface of the soft liner 82. After all appropriate surfaces have been properly treated with release agents, areas 78 and 110 are then filled or packed with a curabel denture base resin designated 112 in FIG. 4 of the drawings, this material being placed in a fluid or formable state in the recess 78 and the surface 110 and this plastic material 112 being of a character comparable to the hard U-shaped base 76 which is made of hard acrylic plastic or similar suitable material, or of a character of durometer hardness when cured and at body temperature suitable to the individual requirements of individual patients with respect to the softness or hardness of the denture base material 112 in relation to the hardness of the U-shaped base 76, which is made of hard acrylic plastic or similar suitable material. 
     When the denture base material 112 is placed against the recess 78 and on the surface 110 the impression model 108 is placed thereover in the flask 102 and a cover 114 of the flask is compressibly closed by wing bolts 116 to compress the compression model 108 against the denture base resin 112 and to form the upper surface of the plastic 112 identical to the original surface of the cured impressionable material which recorded the contour detail of the individual patient&#39;s mouth onto surface 90, to which the finished dentures will ultimately fit. 
     Alternately or preferably an ejector flask, such as that manufactured by Hanan Manufacturing Company may be compressed closed in the conventional flasking manner. 
     After the plastic 112 has been placed in the mould between the impression models 100 and 108, as shown in FIG. 4, the plastic 112 is allowed to cure and bond to the surface 78 of the hard U-shaped assembly 76 and to harden to an ultimate consistency substantially equal to that of the hard base 76, or to varying degrees of durometer hardness or softness as is determined by the various denture base compounds suitable to these methods and techniques. 
     The impression models 100 and 108 are then removed from the flask 102 and are separated at the parting line 106 and the finished dentures, unitarily bonded together, including the cured base resin 112 and the hard U-shaped assembly of teeth 76 and 74, are then removed, cleaned, polished, and are ready for final delivery to the individual patient. 
     It must be appreciated that the various materials used in accordance with the foregoing methods may vary within the limit of equivalency as for example, the teeth 74 may be of hard acrylic, silicone, porcelain, or other suitable material, held in bonded relationship by plastic, metal, wax, rubber or other such materials used as stabilizing devices or reinforcement devices. The U-shaped base assembly may be constructed of any durometer hardness or softness a material, when cured and at body temperature. The soft deflectable liner may be of any suitable material such as plastic, metal, wax, clay compounds, rubber compounds and the like, each with or without plastic, metal, wax or other such materials in combination. The impressionable liner 90 may be any material such as would accurately record the intimate contours of the oral cavity and gum supporting areas of the mouth; such materials as impression material or hard or soft liner material. The denture base material may be of any suitable denture base material having any of a range of durometer hardness or softness, as is dictated by the availability of such resins and the individual requirements of various individual dentists and patients. 
     The materials from which the impression models 100 and 108, as well as the plaster 104, are formed may be commonly known as casting stone or dental stone, or may be of other resilient or non-resilient materials such as metal, urethane, monothane, teflon and the like, and may be conventionally known to persons who use such materials for purpose of investment casting where moulds are made in accordance with the lost wax process. These methods and materials are well known to persons skilled in the art. Further, it will be understood that the pliable or soft formable portions of the denture module may include all pliable materials, either plastic, metal, wax, clay compounds, rubber compounds with or without reinforcing devices or elements which may be comparable or equivalent in use. 
     The U-shaped assembly of teeth referred to herein include any tooth structure maintained in position by the use of plastic, metal, wax, clay, gypsum or other such elements; or by pre-setting such U-shaped assembly of teeth in a form wherein a formable and/or an impressionable material shall be combined to register the intimate impression of an individual patient&#39;s mouth for use in conjunction with any of the methods, or techniques disclosed herein. 
     Further, it should be appreciated that any materials referred to herein shall be construed to include both chemically activated resins and heat curing resins. 
     The method as described herein may be construed to relate to the hard liner 90 and the deflectable layer 82 in that any dental device of such character utilizing any formable or impressionable material is removed by any means from any U-shaped assembly of prosthetic teeth, (with or without plastic, metal, or wax reinforcing devices or materials) or form wherein a U-shaped assembly of prosthetic teeth is held and whereupon a permanent or temporary gum fitting structure is affixed to said U-shaped assembly for purposes of registering a relationship of the intimate contours of the human mouth of an individual to said U-shaped assembly when used in conjunction with any of the methods cited herein. The method as described herein may be also construed to include the use of matrix devices designated to register the relationship of the gum supporting areas of the oral cavity to a U-shaped assembly of teeth. 
     As shown in FIG. 5 of the drawings, a denture module similar to that shown in FIG. 1 comprises the same basic elements disclosed in FIG. 1. In addition, a layer of rubber cement designated 120. This layer of rubber cement 120 is disposed between the soft deflectable layer 86 and the hard base 78. This rubber cement 120 provides for the removal of the deflectably formable layer 86 and the hard liner 90 from the hard base 78, as hereinbefore described in connection with FIG. 3 of the drawings. The rubber cement forms a convenient cleavage so as to permit the deflectably formable layer 86 and hard liner 90 to be quickly removed from the hard base 78; preliminary to the final casting operation, as shown and described in connection with FIG. 4 of the drawings. 
     A further modification shown in FIG. 6 of the drawings comprises a hard base 78 with a recess 122 therein and the soft liner 86 is moulded such that a projection thereof is disposed in said recess 122; the projection being designated 124 which serves to connect the soft deflectable layer 86 with the hard base 78 and to thereby provide for a simple means by which the soft layer 86 may be stripped from the hard base simply by pulling the projection 24 out of the socket 122. It will be understood that several of these sockets 122 may be disposed about the generally U-shaped hard base so as to provide acurate holding of the soft deflectably formable layer 86 relative to the hard base 78 until such time that it is removed therefrom as hereinbefore described in connection with FIG. 3 of the drawings and preliminary to the final casting operation as hereinbefore described in connection with FIG. 4 of the drawings. 
     In the modification as shown in FIG. 8 of the drawings, screws 126 are provided with counter sunk heads 128 which are counter sunk in the upper portion 130 of the soft deflectably formable layer 86. These screws 126 are threaded into threaded holes 132 in the hard base 78. Thus, these screws removeably connect the deflectably formable layer 86 relative to the hard base 76 and when it is desired to strip the layer 86 from the hard base 76 as described in connection with FIG. 3 of the drawings, the screws 128 are removed by a conventional screwdriver and then the soft deflectably formable layer may be readily stripped away from the hard base 76. 
     Several of these screws 126 may be used to connect the layer 86 with the hard base 76 and the screws are disposed in spaced relation around the hard base structure and these screws have an advantage in that they do not require any cement or other material to be placed between the layer 86 and the hard base 76 and thereby afford a removeable connection means which is clean and does not require any cleaning of the hard base 76 in the mould as shown in FIG. 3 preliminary to the casting of the final denture, as described in connection with FIG. 4 of the drawings. 
     In accordance with the foregoing, it will be appreciated that the removable connection of the deflectalby formable layer 86 from the hard base 76 preliminary to the final casting operation shown in FIG. 4 may be varied in accordance with the disclosures of FIGS. 5 to 8 in accordance with various equivalents thereof. 
     As shown in FIG. 12 of the drawings, a generally U-shaped assembly of teeth designated 140 is similar to the assembly of teeth shown in the Huey U.S. Pat. No. 3,727,309 in which a generally U-shaped metal member 142 interconnects the teeth to hold them in generally U-shaped assembly. 
     It will be understood that the assembly of teeth 140 may be moulded in a single integral assembly, as disclosed in the Hazar U.S. Pat. No. 3,839,796, and in either instance the generally U-shaped assembly of teeth 140 is not provided with a hard base such as the base 76, hereinbefore described. 
     Removeably moulded onto the assembly of teeth 140 is a soft deflectably formable layer 144, as shown in FIGS. 9 and 12. Thus, the deflectably formable layer 144 is the equivilent of the layer 86, hereinbefore described, but is removeably connected directly to the assembly of teeth 140; as for example protruding nibs 146 represent one method of removeably securing the soft deflectably formable layer 144 to the assembly of teeth 140 so that the layer 144 may be stripped from the assembly of teeth to provide the facility as shown in FIG. 10 of the drawings and generally described in the hereinbefore disclosed subject matter related to FIG. 3 of the drawings. It will be understood that the soft deflectably formable layer 144 may be secured to the assembly of teeth 140 in such a manner that it may be readily removed to attain the disposition of the assembly of teeth 140 as shown in FIG. 10, so that the final impression shaped denture material may be moulded thereon as shown in FIG. 11 of the drawings and generally in conformance with the method described in connection with FIG. 4 of the drawings. 
     In the method of the invention, as shown in FIGS. 9 to 12 of the drawings, the denture module, including the assembly of teeth 140 and the soft deflectably formable layer 144, may be initially fitted to the patient&#39;s mouth in the same manner as described in connection with FIG. 1 of the drawings and in the Hazar U.S. Pat. No. 3,839,796 so that the soft deflectably formable layer 144 may be initially fitted to the patient&#39;s mouth and then a hard liner 146 may subsequently be impression formed in the patient&#39;s mouth in a manner similar to that described in FIG. 1 of the drawings, and involving the hard liner 90. Thus, the liner 146 is equivilent to the hard liner 90 shown in FIGS. 1 and 2 of the drawings. Corresponding with the moulding operation described in connection with FIG. 3, the moulding operation described in FIG. 10 involves the stripping away of the soft deflectably formable layer 144 from the assembly of teeth 140 and from the projections 146 so that the final casting 148 of the denture may be made in the mould as shown in FIG. 11, such that the casting 148 may bond to the assembly of teeth 140; the assembly of teeth 140 preferably being an acrylic material and the final casting 148 being made of an acrylic material and such as to conform to the impression fitted dental module shown in FIG. 9 of the drawings and also as previously described in FIG. 1 of the drawings. It will be appreciated by those skilled in the art that the tear away of the soft deflectably formable layer 144 from its removeable connection with the assembly of teeth 140 provides a very clean method by which the assembly of teeth 140 may be left clean and free to attain a bonded relationship with the final casting 148 which is produced in relation to the moulds as previously disclosed in FIGS. 2, 3 and 4 of the drawings and as shown correspondingly in FIGS. 9, 10 and 11 of the drawings. 
     It will be appreciated that all diagrams and illustrations portray the proximal denture plate, and that all methods disclosed and cited herein should be construed to include also the mandibular denture plate, in all respects. 
     It will be obvious to those skilled in the art that various modifications of the invention may be resorted to without departing from the spirit of the invention.