US1955709A - Method of and means for producing dental plates - Google Patents

Description

April 17 1934. J KlNSLEY 1,955,709

METHOD OF AND MEANS FOR PRODUCING DENTAL PLATES Filed May 6, 1929 fig; 3

Patented Apr. 17, 1934 sarseir series @F AND MEANS FGR PRODUCING DENTAL LLATES Jason D. Kinsley, Cedar Rapids, Iowa Application May 6, 1929, Serial No. 360,961

20 Claims.

This invention relates to the making of rigid or substantially rigid counterparts of more or less {solid objects, more especially the making of counterparts for use in that branch of surgery known as 'prosthodontia or plate-work. Among the objects of this invention are to provide a process which will reduce the errors of operation which are'b'ommonly introduced during the process of m a'king dentures; to provide improved apparatus fer the purpose indicated; to provide improved means and methods of forming substantially rigid counterparts of rigid or semi-rigid physical surfaces; and such further objects, advantages and capabilities as will hereafter appear and as are inherent in the structure and method disclosed herein. My invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying drawing, and, while I have shown therein what is now considered the preferred embodiment of this invention, from its physical aspect l desire this disclosure to be understood as illustrative only and not to be interpreted in a limiting sense. As this invention applies to prosthodontia its principal object is to provide a process and means whereby an individual impression tray may be :quickly, cheaply and easily constructed. It has as a further object the provision of a process which facilitates the construction of better bite plates, or trial plates, for use in denture construction without the necessity of making a transfer of the same to or from a model of the gum- "ridge. As this method applies to plate work, I term it the non-transfer method. Among the advantages of this method are better fitting dentures, fewer failures, greater accuracy in construe tionjelimination of a bulky stock of dental trays and apparatus required in all other methods of denture construction, less time consumed by the dentist, fewer appointments with the patient, and a. more perfect guidance for all subsequent mechanical procedure.

In order that there may be a more complete and better understanding of the following specification and claims it is deemed advisable to define certain terms used herein in simple and comprehensive language. These terms are as follows: Denture patte1'n.A test plate having for its base and supporting structure a bite unit, the concavity of which contains the impression of the gum-ridge and the convexity supports the bite rim material so formed as to reproduce the general contourof the lost teeth and their supporting tissues and the crest of which registers the correct occlusal surface.

Fig. 5 shows the same as above with the pro= tective covering removed and the margins of the tray trimmed to the desired limitations in preparation for the act of turning back the margin to form a smooth edge.-

Fig( 6 shows the samev with anchorage upon the convex contour, or ridge, and made rigid by a process of infiltration with a quick setting fluid.

Fig. '7 shows upper and lower bite units in relative position as when in the mouth but before the bite-rims have been formed on the anchorages.

Fig. 8 shows an upper bite unit with abrasive rims formed upon its ridge and covering its anchorages, now'in preparation to receive plastic material within its concavity and ready for the taking of an impression of the patients gumridge.

Fig. 9 shows a pair of completed denture patterns with the occlusal planes ground or molded to perfection by the movement of the jaws in the act of chewing, and with retaining grooves formed across the junction of the two bite rims on the buccal surfaces.

Fig. 10 shows a pair of completed upper and lower denture patternsthe same being held in correct relationship to each other, as when in the mouth, by a simple coupling means comprising a key-plate filled with hard wax which has been heated to plasticity and pressed against the buccal surfaces of the pattern so as to fill the grooves while the patterns are held in centric relation by the patient closing the jaws and holding them in normal position.

Fig. 11 shows'the inner side of the wax registry of the key-plate. Fig. 12 represents a fragment of a suitable anchor strip.

In order to find out more fully the differences between the old method and the new and the advantages of the latter, it is necessary to state herein some of the shortcomings of the prior practice with regard to the making of dentures.

In the first place, the commercial tray, such as is most commonly used in practice, does not fit the gum ridge, in the vast percentage of cases, closely or uniformly enough to effect an even and perfect distribution of plastic material about the gum-ridge. In a large majority of cases, it is merely an approximation but, since a fair approximation can be secured by the use of a large number of dental impression trays, the method has been followed by the profession as offering the best expedient available. In contrast to this, the special tray of my invention is made to fit the individual case perfectly and, consequently, enables the operator to secure a perfect impression in all cases, and such special tray is made practical and useful in distinction from all other special types of individual trays by reason of the herein disclosed rapid, inexpensive and accurate process for the construction of the same.

The bite unit serves a twofold purpose; First, holding within its concavity, any of the common- 1y used impression materials such as plaster of paris, modeling compound and the like; second, providing upon its convex contour, improved means of anchorage for and reinforcement of any of the commonly used bite rim materials such as bees-wax or an abrasive. Combining in one unit the perfected impression of a patients gumridge, on one contour of a bite unit, and the bite rim, upon the opposite contour-of the same, provides simple, easy and accurate means by which perfect fitting dentures (dental plates) may be constructed and delivered to the patient, with but one sitting being required for all preliminaries to the laboratory or mechanical procedure. In this way,-the unavoidable hazards encountered bymaking numerous transfers, as is common to all other methods of plate work, are obviated. As indicated above, the present method is termed a non transfer method while all other methods are referred to as transfer methods. In any course of procedurefor plate work, a perfect impression of the gum-ridge is essential to a perfect fit of a denture. Such an impression cannot be secured without the aid of 'a suitable impression tray which must serve as an exact means of equally distributing plastic impression material, the-same recording in minutest detail the contour and periphery of the surfaces against which the finished denture is to rest. Such a tray is easily provided for any case by following the herein described process, and may or may not be provided with anchorages for bite material. As a simple impression taking device, it has the above described requirements and is applicable to any transfer method, and at the same time may easily be'converted into a bite unit, by constructing anchorages upon its convexity.

The transfer method is based upon the hypothesis that accurate reproductions of surface 'contours, and the relative anatomical positions and relations of models for a given case, in plate work, can be accomplished by means of wax transfers from model to mouth and from mouth back to model without danger of error or misplacement. The procedure of the transfer method is to first construct the biteplates of hard wax or like material upon castsor models of a patients mouth and then remove and transfer said bite-plate from said model'to said mouth for the purpose of determining the correct bite, after which another transfer is made carrying the wax bite plate back again from the mouth to the model and fixing said models and bite plates in their supposedly correct original relationship. This procedure proves exceedingly hazardous to plate work as most models of human mouths have undercuts in them to a greater or less degree. It is obvious that making a hard Wax bite plate, as above described, which is constructed by heating rigid wax to plasticity and then pressing it to close conformity to the surface contour of the plaster model having undercuts, and allowing said wax to cool to rigidity, constructs a plate of wax upon said model which cannot be removed therefrom without distortion and injury to said wax plate, said model or both, a consequence which inevitably results in corresponding degrees of imperfection in the finished dentures. Such procedure is quite often responsible for ill-fitting dental plates.

Under the transfer methods six distinct steps in procedure are followed as described below:

1. An impression of the gum-ridge is taken by the dentist in some form of tray selected for impression taking only, and then plaster of paris or the like is poured into said impression and a model formed which is then separated from said impression. When dentures are to be made for "i both upper and lower jaws, the same procedure is followed in both cases.

2. Abite plate is then formed upon each mode as above described.

3. A medium soft wax bite rim is then formed by softening such wax with heat and pressing it upon the convex contour of the bite plate described in step 2.

4. This step comprises the removal of the wax bite plate from the model upon which it has been formed. If the bite plate is made of medium soft or yielding Wax it is sure to be bent out of shape (distorted). If it is made of hard, rigid wax it'is likely to mar the model or break the wax, under thestress of forcibly separating the two. the separation has been accomplished, the bite plate is transferred to the patients mouth;

5. The fifth step involves the manipulation in the patients mouth, the most common practice being to first warm the'crests of the two bite rims so as to soften them somewhat'and then, having placed the plates in the patients mouth, have the patient compress the said bite rims by bring.- ing the jaws to their normal centric relationship when closed. Another practice, in the construction of both upper and lower dentures, is to furrow out the center of said wax bite rims from end to end, along their crest, and fill-said furrow with an-abrasive material such as described above, the object in this case being to provide meansby which the patient can grind or'mill in his own bite to correct occlusion. This is a very excellent object, but there is very inadequate provision'for accomplishing same, as the softening wax rim, while at the temperature of the mouth, yields under the stress of the jaws in the act of chewing or milling, and obviously, this causes breaking and crumbling of theabrasive and, in case this does not occur, the softened wax smears overthe abrasive and interferes with the milling procedure. In either of the'above practices the bite plate is likelyto be distorted by the removal and transfer from its respective model to the mouth and consequently there results inaccuracy in either the bite taking or grinding process within the mouth. After the grinding-in or bite taking operation, the bite rims are attached together in the patients mouth'in their supposedly correct relation.

6. This step is to transfer the bite rims, attached After together as indicated in step 5, back to their original positions, each upon its respective model. This step is exceedingly hazardous and doubtful and in altogether too large a percentage of cases the plates are never replaced with technical exactness due to the distortion of the wax plates or the models or both. This leaves the dentist in .the position of having to guess at their proper relationship, fix them in the position which he guesses to be correct and take his chances on the final outcome. The misplacement of either upper or lower or both models within their respective bite plates, to the slightest degree, in this step, is sure to result in an equivalent degree of inac curacy in the final relationship of the dentures in the patients mouth. Therefore, the hypoth esis referred to above proves to be unsound.

An injury to a plaster model by reason of forcible removal of a rigid wax bite plate therefrom is certain to be registered in the tissue contacting surface of the finished denture and to cause no little distress to the patient and consequent annoyance to the dentist, who is usually at a loss to know just where to relieve the trouble, and often causes an added injury to the plate in the attempt to remedy the difficulty.

It will readily be seen that the non-transfer method obviates every one of the causes for inaccuracy, miss-fit, distress and annoyance as described above in steps 4, 5, and 6, as these steps are entirely eliminated from the procedure followed in the non-transfer technic, a fact which is made possible by the invention of the bite unit, with the accompanying process for making the same.

7 In the following description of the various steps in the non-transfer method, it is understood that the operations for either upper or lower cases are practically the same, and that, unless a contrary interpretation of the language is necessary, reference to either upper or lower is intended in a comprehensive sense and is meant to include both.

Reference will now be made in greater detail to the annexed drawing wherein the lower tray matrix is indicated by the numeral and the upper tray matrix by the numeral 6. These matrices are formed of a porous, pliable material capable of being manually moulded by pressure to conform approximately to the gum ridge and of remaining in the moulded form after being removed from the mouth. This material should be capable of being rendered rigid or substantially rigid by infiltration in the application of a coating of quick setting fluid after it has been removed from the mouth. After the matrix has been manually moulded by pressure to conform approximately to the gum ridge so that it takes the proper conformation, it may be rendered substantially rigid so as to keep this shape while under the stresses to which it is later subjected. In practice, the preferred material is a light, rather close-meshed brass wire-cloth, which, when annealed, may be pressed by the fingers close to the patients gum, and conformed thereto. It sometimes happens that there is an excess of material at the point indicated by the line 8 in Figs. 2 and 3 and this excess may be removed by cutting away a portion of the screen. Removing this excess of material will make it possible to fit the matrix more closely to the gum ridges and do away with some buckling which might otherwise be present.

As a protection against any scratching of the tissues of the mouth by the sharp edges of the woven metal matrix, a soft, pliable covering 9 is supplied which envelops the matrix, as illustrated in Fig. 3. An excellent material for this purpose is chamois skin, but a thinner material is preferred which will permit the matrix to be fitted more closely to the gum-ridge. In Fig.- 12 there is shown a metallic strip 10 having tangs 10a extending therefrom. In Fig. 6 such a strip is shown secured to a special tray to form a bite unit. The ends of strip 10 are indicated at 1012 in Fig. 6 as being bent down over the edge of the tray to hold the same assembled with the tray. Also some of the tangs are indicated at 100 as being bent around the edge of the tray for this purpose. The remaining tangs 10a serve as anchorages for the bite rims 11 and lie, the finished occlusal surface of which is denoted by numeral 111). A key-plate 12 (Figs. 10 and 11) having hard wax adhering thereto is used to tie two denture patterns together as indicated in Fig. 10. the patterns having grooves 13 carved therein across the plane of the meeting surfaces to assure perfect matching of the patterns in case it should be necessary later to match them. These grooves also assist in holding the patterns together by reason of providing points of attachment for the wax. Their use will be referred to more fully hereinafter. If desired the patterns may be further secured together by a few drops of sealing wax as indicated at 14.

In practicing this method, the dentist, at the first sitting of the patient, selects the proper size of tray-matrix, enveloped by a protecting shield 9, as heretofore indicated, and places this in the patients mouth, pressing the same, with his fingers, against the palate and into close conforinity with the gum-ridge, the margins of the matrix being then folded up around the gumridge to a preliminary tray-like form, as shown in Fig. 4. After this the operator, with apencil or the like, outlines the margins in conformity with the periphery of his case. The formed matrix is then removed from the mouth and trimmed to the periphery, a slight margin being left to be turned over so as to form a smooth edge around the matrix. The covering is then removed and the edge of the matrix is rolled back to the line of the periphery, providing ample clearance for all muscle attachments. After this op eration the matrix may be replaced upon the gum, for final perfection of form, if the operator desires. He then removes the formed, perfected matrix from the mouth and dips it in a bath of soldering flux, then into a bath of molten solder or babbit metal, or the like. The tray-matrix is then removed from the molten metal and allowed to cool so that the metal hardens. For this purpose of stiffening the tray, various fluid ma terials, which harden quickly may be utilized but, in practice, the most suitable material I have found is solder or babbit metal which, upon'being cooled, leaves a substantially rigid impression tray which may or may not be provided with anchorages upon its convex contour as the operator desires and as shown in Fig. 6. I

By this process the tray matrix becomes a special tray adaptable to all methods of plate work now in practice. As a further means of obviating the transfers herein referred to (see transfer method above), the dentist now forms anchorages upon the convex surface of the special tray. This may be done by the addition of a strip of metal having tangs thereon, as shown in Fig. 12. The strips 10, with their tangs 10a, serve as reinforcements for the bite rim' material and the perfected tray. The bite-rim material may be either wax, abrasive, or any other suitable matechanical constructions.

rial. The dentist has now constructed a bite unit (see Fig. 6) and proceeds to procure a fect impression'of the gum ridge within the concavity of said bite unit and a perfected bite rim upon the convexity thereof. 'It matters little which is done first.

We will assume first that the structure of Fig. 6 has been made and that'it is'desired to take an impression of the gum ridge corresponding thereto. In doing this the concavity ofthe bite unit is charged with impression material, prefeilabl y modeling compound and then the same is inserted in the mouth and pressed over and about the gum ridge in even and uniform distribution, and in close conformation therewith. When the impression has been taken, the bite unit is removed from the mouth and a bite rim constructed thereon, forming the structure illustrated in Fig. 8, or, as above stated, said bite rim may be constructed before the taking of said impression. This bite rim may be made from wax, abrasive, or the like. It will of course be understood that this will be for both upper and lower gum ridges. The impression material isaccurately formed within the concavity of the bite unit and is rigidly held thereby, being substantially a part thereof. Afterthis, the bite unit is removed from the'mouth and has upon its ridge and over and about the upstanding anchorages 10a a bit rim 11 or 11a, preferably of abrasive material which is' held rigid by the anchorages referred to above. This having been done for both upper and lower gum ridges, the two units corresponding to Fig. 8 are placed in the patients mouth as indicated in Fig. 9 and the exteriors thereof are formed, the two units having the same general form and positional relationship as that of the natural teeth and their supporting tissues. The patient is then instruct-- ed to perform the act of chewing upon the crest of the abrasive rims and this grinds and perfects the occlusal surface. 11b. Retaining grooves 13 are then carved across the junction of the two bite-rims as indicated in Fig. 9 and the rims are attached together by means of a keyplate 12 filled with hard wax heated to plasticity and pressed over the junction of the rims, the same entering the grooves 13 so that perfect registry can always thereafter be secured. The patient is now dismissed and will not need to call again until the dentures are finished, since the dentist now possesses perfect denture patterns for his patients artificial teeth. These serve as an infallible guide for all subsequent me- The bite, contour, occlusal surface, all registrations and markings he may desire, and the perfected impressions for his case are supplied by the denture patterns. As the models have not yet been poured, it is obvious that no transfers as described for all other methods are herein employed. -The next step after completing the denture patterns is to pour the models in the impressions thus taken within the bite units, and with the bite units held in relation by the key plate 12; and in conjunction with an "articulator.

The sequence of operations thus described at length does not in practice consume a great amountof time. Without subjecting thepatient to a very long wait it is possible to dismiss the patient after the first appointment and at the next call deliver to him an accurately fitting and completed pair of dental plates.

Having thus described my invention, I claim.

1. The described method of producing'a dental impression tray or form, which consists in pressing a sheet of thin, pliable material about the gum, withdrawing it and rendering it rigid by applying to it a liquid which becomes hard on solidifying.

2. The described method of producing a dental impression tray or form, which consists in pressing a sheet of thin, pliable material about the gum, withdrawing it and rendering it rigid by a bath in molten metal.

3. The described method of producing a dental impression tray or form, which consists in pressing a sheet of thin, pliable material about the gum overan interposed sheet of soft and limp material, withdrawing the adherent sheets, separating them, and rendering the formed sheet rigid by the application of a solidifying liquid.

4. The described method of producing a dental impression tray, which consists in molding by pressure about the gum a sheet of thin, pliable material, applying to the form so made a hardsetting liquid to fix its shape, applying to the stiff form an anchorage for plastic material, and firmly connecting the form and anchorage.

' 5. An improved method of producing a piece of dental apparatus, which consists in forming by pressure about the gum a sheet of thin, pliable material, fixing its 'form by the application of a hard-setting liquid, attaching to the ridge an upstanding anchorage for plastic material, and forming on the bite unit thus formed and over the anchorages a bite-rim of plastic material impregnated with an abrasive.

6. An improved method of producing dental bite-units. which consists in forming by pressure about the gum a sheet of thin, pliable material,

fixing its form by the application of a hard-setting liquid, attaching to the ridge an upstanding anchorage for plastic material, forming on the bite unit and over the anchorage a bite-rim of plastic material impregnated with an abrasive, and charging the matrix with an impression compound.

7. A special tray formed of light and pliable woven wire molded to form about the patients gum, and said wire being embedded in rigid metal whereby the wire is fixed in form. 8. A bite unit formed of light and pliable woven wire molded to form about the patients gums, said wire being embedded in rigid metal whereby the wire is fixed in form, and provided along its ridge with anchoring projections to retain a bite-rim of plastic material.

9. The described method of determining the bite in the forming and fitting of dental plates, which consists in pressing a tray matrix to conformation with the gum ridge, rendering the same rigid by the application of a solidifying liquid, building a bite rim on each ridge of hardening plastic material impregnated with m abrasive, perfecting an impression of each respective gum-ridge, and with both denture patterns in the mouth, finally grinding the rims to the biteline by the natural and varied movements of the patients jaws.

10. The method of producing a removable and replaceable solid counterpart of a solid or semisolid material surface contour by forming a matrix of pliable porous material about it and infiltrating smd matrix material with a quicksetting liquid which, on solidification, renders the matrix material solid and rigid like.

11; The method of producing a special tray which consists in pressing a matrix of pliable porous sheet material about the gum, withdrawing the same, and rendering it hard and firm by infiltration with fluent metal which quickly solidifies at normal temperature.

12. The method of producing a dental tray which comprises covering a matrix of thin pliable porous material with a sheet of tough flexible material and, while thus covered, pressing it to form about the gum, removing it therefrom, withdrawing said covering, and rendering said matrix solid. and firm by application of a fluid material which solidifies.

13. The method of procuring the bite which consists in shaping a matrix of pliable porous material to fit the gum-ridge, rendering said matrix hard by applying thereto a solidifying fluid material, providing anchorages on the convex surface of the shaped matrix, charging the concavity thereof with impression material, taking an impression of the gum ridge therein, forming a bite-rim upon and about the anchorages thereof, and finishing the bite-rim.

14. The method of making denture patterns which comprises fashioning sheets of pliable porous metallic material into close conformity with the gum-ridges of a patients mouth, infiltrating the so shaped material with fluid metal which becomes hard at normal temperature, removing the same and permitting hardening to take place, providing the convex surface of the shaped material with anchorages, forming over and about said anchorages an abrasive bite-rim for each pattern, lining the concavity of each with impression material, placing the patterns one at a time in the patients mouth each upon its corresponding gum-ridge, manipulating each pattern separately so as toeffect an equal dis tribution and adaptation of said material to and about said gum-ridge, and causing the crests of the bite-plates to be ground within the patients mouth, each against the other until the correct occlusal surface is formed upon each of the said crests.

15. As an article of manufacture, a piece of porous, felt or fabric-like material, capable of being made rigid upon infiltration with a rapidlysolidifying fluent material, and being of a form suitable to be applied to a human tissue and,

when so applied, to be shaped thereto, said material having a tough flexible substance enclosing the edges thereof for the protection of the bodily tissues when applied thereto, said substance being easily removed from said material after the latter has been molded to desired form.

16. An article as defined in claim 15 which is cut to a form approximating the periphery of a gum-ridge and has an area suificient to permit modeling same to flt and completely cover the gum-ridge.

17. As an article of manufacture, a piece of porous material capable of being made rigid upon infiltration with a rapidly solidifying fluent material, the same being of a form and physical character suitable to be applied to a human tissue and, when so applied, to be shaped thereto and, when so shaped, to retain its form when being handled, said porous material having a covering normally preventing access of air thereto, said covering material being readily removable for use of the porous material.

18. The method of producing a bite-unit which consists in forming about the gum-ridge a matrix of pliable, porous material, fixing its form by the application of a hard setting fluid material, providing its ridge with an upstanding anchorage for bite-rim material, and forming upon and about said anchorage any desired form of bite-rim.

19. A method of quickly producing a special dental impression tray which comprises forming a sheet of porous pliable metallic fabric to fit a dental tissue surface of which an impression is desired, and infiltrating the formed fabric with fluent metal which will cohere therewith and become solid.

20. A method of quickly producing a special dental impression tray which comprises forming a sheet of porous pliable metallic fabric to fit a dental tissue surface of which an impression is desired, treating it with a soldering flux, infiltrating said fabric with a fluent metal, and removing the fabric into such conditions as will cause the fluent metal to quickly become solid and coherent with said fabric.

JASON D. KINSLEY.

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