Method and Apparatus to Produce Artificial Dentures

The production of artificial dentures is an art which has existed for at least several hundred years and over that period has constantly been improved to achieve the ultimate goal of maximum comfort to persons wearing such dentures and close simulation to natural dentitions. One of the principal difficulties involved in the preparation of artificial dentures comprises the arranging of artificial teeth and connecting the same to denture base material to produce finished dentures. The majority of dentures made at the present time include the connection of sets of individual artificial teeth to the denture base material and this is accomplished, in the main, by dental laboratories, but is by no means restricted to the same in that some dentists prefer to fabricate the dentures for their patients.

In general, the preparation of full dentures commences with taking impressions of both upper and lower edentulous arches, and establishing their relative position to one another both at rest and in function. These methods are described in texts and other publications, and result generally in the preparation of a "bite record" used by the dental laboratory from which a try-in is fashioned.

The impressions are taken by procedures well known to the art using alginate impression material or the like, and models of the patient's jaws and gums, known as casts are formed from setable materials such as certain gypsum material, commonly referred to as "dental stone". A baseplate is next formed upon the cast using a thermoplastic material in sheet form, by softening and adapting it over the cast. Upper and lower baseplates prepared in this manner are then used by the dentist to establish a bite record. The baseplates are introduced into the mouth of the patient, separated by soft wax which is deformed by the action of the patient's jaws as they are guided into their proper position by the dentist. The soft wax is modeled in a relatively rough labial contour of the teeth as they will be positioned in the finished denture, and the relationship between the jaws is transferred to a dental articulator which serves to hold the casts in the same relative position, as described in greater detail hereinafter. Also, certain measurements made with appropriate instruments determine the preferred vertical relation between the central, forward portions of a patient's gums on the respective jaws, known professionally as the "incisive papilla".

Individual posterior and anterior artificial teeth then are imbedded in wax material, known as "set-up wax", applied to the baseplates to conform to surfaces determined by the "bite record". Then additional wax is applied between the gingival surfaces of the artificial teeth and the baseplates in a manner to resemble natural gum contours. The foregoing operations are performed while the casts are mounted in the upper and lower bows or members of an articulator which permits relative movement between the upper and lower sets of artificial teeth formed on the casts by the foregoing procedures and thereby enables a dental technician or dentist to provide desirable occlusion and function between the artificial teeth on the respective casts. Mounting such teeth on the cast or model by the foregoing procedure requires extensive skill and is relatively time-consuming. The elimination of such substantial consumption of time is an essential objective of the present invention.

After the above procedures have been completed, the baseplates and the contoured wax material and artificial teeth mounted thereon then are removed from the casts respectively and may be tried in the mouth of the patient if desired. With the upper and lower casts attached thereto, they are then invested in suitable molding compounds, generally of a gypsum nature. The baseplate and set-up wax are removed from the hardened investment by heating and softening methods to provide a cavity into which permanent denture base material is injected or molded for connection to the ridgelap and gingival surfaces of the artificial teeth by the well-known "lost wax" process.

The foregoing procedure is generally exemplary of the methods used at present to fabricate artificial dentures. Various modified steps of the procedure occur at present, but in general, it will be seen that one of the principal difficulties arising from the procedure comprises the mounting of individual artificial teeth upon the wax substrate to which they are attached and also to provide proper occlusion between the opposed masticating surfaces of the teeth in the upper and lower dentures.

One of the improvements offered by the present invention in at least one principal aspect comprises the use of full arch upper and lower sets of artificial teeth which are integrally connected together in said sets and opposite sides of each arch formation are braced to stabilize the shape. The teeth provided in said full arch sets have certain characteristics which resemble natural teeth, while at the same time, facilitating the molding of such teeth in molds which preferably are relatively simple. In this regard, it is to be noted that the use of full arch sets of artificial teeth to form dentures is not new from a basic standpoint. Previous attempts to simplify the formation of artificial dentures have included the use of such full arch sets of artificial teeth and typical examples of the same are found in such prior U.S. Patents as U.S. Pat. No. 1,814,717 to Maizner dated July 14, 1931; U.S. Pat. No. 2,539,882 to Zilinski, dated Jan. 30, 1951; U.S. Pat. No. 2,768,440 to Elliott, dated Oct. 30, 1956; and U.S. Pat. No. 4,099,329 to Hawthorne, dated July 11, 1978.

In addition to the use of full arch sets of artificial teeth in the making of dentures as noted above, various procedures for the forming of dentures with the aid o articulators in order to attempt to minimize the amount of time consumed have been the subject matter of other prior U.S. Patents including U.S. Pat. No. 1,814,717 to Maizner, dated July 14, 1931; U.S. Pat. No. 2,171,759 to Meyer, dated Sept. 5, 1939; and U.S. Pat. No. 4,189,837 to Stele, dated Feb. 26, 1980, as well as prior British patent No. 295,768 to Perks, dated Aug. 23, 1928 and prior German patent No. 508,921 to Kantorowicz, dated Oct. 2, 1930.

Further to facilitate the formation of artificial teeth with an enamel simulating layer, prior U.S. Pat. No. 1,547,643 to Clapp, dated July 28, 1925, illustrates a form of mold and technique to accomplish this, while prior U.S. Pat. No. 1,907,923 to Willis, dated May 9, 1933, is one example of a measuring device used incidental to determining desirable bite level between artificial dentures and thereby facilitate the comfort of using the same.

The characteristics and advantages of the present invention over the techniques and apparatus presently in use, as enumerated above, are set forth below in detail.

It is among the objects of the present invention to improve and simplify the technique of forming artificial dentures primarily by using full arch sets of artificial teeth and employing a process by which said teeth ultimately are fabricated as finished dentures by the employment of procedural steps and apparatus submitted to be improvements over the procedures and apparatus presently in use, both as enumerated above and as practiced presently by dentists and dental technicians in dental laboratories.

In regard to the full arch unitary sets of artificial teeth comprising an important and advantageous feature of the present invention but which, per se, are the subject of a separate related application, the teeth in the anterior portion of the sets in particular are provided with interproximal spaces adjacent the gingival portions of the teeth for purposes of permitting denture base material to be positioned between the gingival areas and thus, resemble natural gums, and in regard to both the anterior and posterior teeth, the labial and buccal surfaces thereof have been formed to resemble the corresponding surfaces of natural teeth insofar as possible, but said surfaces have been shaped in a manner to readily permit the removal of the molded full arch sets of teeth from rigid molds without interference and with minimum requirements for finishing.

Ancillary to the foregoing object relative to the full arch sets of artificial teeth, the same are provided with stabilizing strut means extending between and connected to opposite sides of the U-shaped configuration of said full arch sets, the strut means comprising fingers extending radially from a central member and the ends of the fingers which are connected to certain of the posterior teeth are of minimal cross-sectional area to facilitate separating the same from the full arch sets of teeth prior to the same being used in the process steps according to the invention and set forth in detail hereinafter.

Another important object and innovation afforded by the present invention comprises the provision of an articulator of a simplified nature and comprising essentially a lower bow or member comprising a base, support members extending upward respectively from the opposite sides of said base adjacent the rear end thereof which comprises a back frame, an upper bow or member pivotally connected at the rearward ends thereof to the upper ends of said support members, and a planar mounting table adapted to be detachably connected at the rearward end thereof to said support members intermediately between said base and upper bow. Said mounting table controls the height of the cast at the posterior end and also positions it horizontally so that the bite plane is parallel within the patient's mouth in relation to the eyes. The mounting table has a mounting bar extending perpendicularly from one surface of the table, intermediately between opposite ends thereof and parallel to the rearward end of said table for purposes of having the hamular notches in the upper cast of a patient's jaw placed upon said bar to accurately position said cast with respect to the mounting table incident to subsequent operations being performed with respect to said table.

A further object of the present invention concerning the articulator is to render the mounting table reversible selectively to dispose the surface with the mounting bar or the opposite planar smooth surface thereon uppermost incident to subsequent operation of the process of the invention and, incident to the reversibility of the mounting table, a supporting pin is reversibly connectable to the outermost end portion of the table so as normally to extend downwardly for engagement with the base, regardless of which surface of the table is uppermost.

Still another object of the invention ancillary to the foregoing is to provide quickly connectable and disconnectable interfitting lugs and recesses on the rear end of the mounting table and intermediate portions of the support members.

Ancillary to the immediate foregoing object, it is a further object to provide a transverse support bar extending between the support members intermediately of the upper and lower ends thereof for purposes of supporting the rear end of the mounting table, while the aforementioned reversible pin supports the forward end of the table with respect to the base.

A still further object of the present invention is to provide pivotal connections for the rear end of the upper bow to the support members which comprise threaded members and details capable of selectively screwing the threaded members into the innermost position in which the upper bow is capable only of pivotal movement about a horizontal axis, while when the threaded members are backed off a predetermined amount, the pivot means comprise recesses of limited depth and length within a horizontal plane to permit at least limited milling movement between the sets of full arch artificial teeth when respectively supported by the upper bow and the base comprising the lower bow. Such movement is possible in posterior, anterior, and opposite lateral directions relative to centric position.

Having in mind the foregoing objectives pertaining to the full arch sets of upper and lower artificial teeth and the articulator referred to immediately above, it is a further very important object of the invention to provide a method of forming a set of upper and lower artificial dentures, each provided with full arch unitary sets of artificial teeth, comprising basically the steps of using models of a patient's upper and lower jaws and a jaw relation bite record to relate upper and lower casts or models of said jaws therefrom, removably connecting said casts respectively to the upper and lower bows of said articulator while respectively positioned in registry by said bite record, removing the bite record and respectively positioning full arch sets of artificial teeth relative to said models by operatively locating said aforementioned mounting table in said articulator intermediately of the upper and lower bows and placing said full arch set of upper teeth upon said table while said upper cast is supported by the upper bow of the articulator, attaching said upper set of teeth to said upper cast by removable, gum-simulating material, followed by removing the mounting table from the articulator and remounting said lower cast upon the lower bow or base, and then placing a lower full arch set of teeth in normal occlusion with the upper set of teeth and attaching said full arch set of lower teeth to the lower cast by removable gum-simulating material, followed by shaping said removable material on both of said casts to resemble natural gums and remove said sets of teeth and gum-simulating material with the cast thereon from the articulator and processing the same by conventional methods to form a complete set of upper and lower artificial dentures.

Still another object of the foregoing method is to use wax-like material as said removable gum-simulating material, which wax-like material is capable of being removed by the application of heat.

A still further object of the method incident to positioning the upper cast on the mounting table is to place the hamular notches in the upper cast on the aforementioned mounting bar of the mounting table, followed by leveling the upper cast relative to the table by using a stepped, wedge block between the table and the forward curved portion of said upper cast, known as incisive papilla, in accordance with measurements between the upper lip and forward portion of the upper jaw as furnished by a dentist.

One further object of the aforementioned method is to include the additional step of reversing the mounting table in the articulator to present the smooth side uppermost and the mounting bar in depending manner to present a smooth upper surface upon which the full arch set of upper artificial teeth is placed for attachment to the upper cast by removable gum-simulating material.

Still another alternate object of the invention is to employ light-curable moldable denture base and baseplate material, in lieu of wax-like removable material of the type referred to hereinabove, to which the full arch sets of artificial teeth are attached and said material then is shaped to resemble natural gums, after which the material and attached teeth are exposed to light for a sufficient period of time to cure the same into rigid condition to comprise a finished denture requiring no further processing except possible limited trimming and/or polishing.

Another object of the present invention is to provide methods for the formulation of dentures, including partial dentures, having a plurality of artificial teeth. Such dentures are formed by using negative impressions of at least a portion of the jaw of a patient having at least one edentulous portion to make a model of the jaw portion therefrom. An actinic, preferably visible light curable, moldable denture base material is then applied to the model and caused to conform to the edentulous portion of that model. A rigid framework is preferably provided and, in the case of partial dentures, the framework is adapted for affixation to at least one natural tooth structure of the patient's jaw. The framework is then preferably embedded in the denture base material and the denture base material exposed to visible light for a time sufficient to cause hardening thereof into a denture base structure.

Following preparation of the denture base structure which may have a framework embedded therein, a plurality of artificial teeth are movably affixed to the denture base. This is accomplished through the intermediation of an additional quantity of actinic, preferably visible light curable, moldable material, either to the denture base, to the teeth, or to both, followed by the effectuation of contact between the teeth and the denture base. In accordance with the preferred embodiment of the instant invention, the teeth are then irreversibly affixed to the denture base through a "tacking" process.

In accordance with the tacking process, actinic light, preferably visible light, is directed onto minor proportions of the light curable material holding the teeth to the denture base for a period of time sufficient to cure those minor proportions. The application of light is insufficient to cause substantial curing of a major proportion of the entirety of the curable material. In this way, the teeth are rigidly held to the denture base with a small amount of cured polymerizable material. For this tacking process, it is not necessary that the minor proportions be completely cured or hardened. It is only necessary that they be hardened sufficiently as to firmly and irreversibly hold each tooth in place.

It is preferred to align or orient the teeth among themselves and with respect to the denture base prior to the tacking operation. It is preferred to tack individual teeth seriatim to maximize fit and aesthetic appeal. Following tacking and the attainment of a satisfactory orientation of teeth and the denture base, the actinic light curable material is substantially fully hardened by irradiation with actinic, preferably visible, light.

In accordance with another preferred embodiment, additional portions of actinic, preferably visible, light curable, moldable, denture base material are added subsequent to the irreversible affixation of the teeth by tacking. The same is then molded into a replica of gingival tissue to provide improved aesthetic appearance of the denture.

In accordance with a further preferred embodiment, a composition capable of excluding a substantial proportion of oxygen from the surface of the denture base composition is applied subsequent to the irreversible affixation of teeth to the denture base. Upon subsequent substantially complete hardening of the denture base material, the presence of the oxygen barrier layer composition, as described herein, facilitates the improved surface curing thereof.

Details of the foregoing objects and of the invention, as well as other objects thereof, are set forth in the following specification and illustrated in the accompanying drawings comprising a part thereof.

FIG. 1 is a top plan view of an exemplary full arch unitary set of upper artificial teeth, embodying the principles of the present invention.

FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1 and showing the cross-section of a central tooth of the set of full arch teeth, shown in FIG. 1, the labial face of the tooth sloping in at the gingival and out at the incisal, to facilitate removing the teeth from a mold.

FIG. 2a is a view corresponding to FIG. 2, but showing the cross-sectional shape of a normal central artificial tooth in which the labial face of the tooth is in at the incisal, which would impair the removal of the tooth from the type of mold preferred to manufacture the teeth of the present invention.

FIG. 2 is a vertical sectional view of a canine tooth of the set shown in FIG. 1, as seen on the line 3--3 thereof, and illustrating as in regard to FIG. 2, the manner in which the canine tooth slopes inwardly at the gingival and outwardly at the incisal to facilitate the removal of the same from the mold.

FIG. 3a is a view similar to FIG. 3, but shows a sectional view of a more or less conventional canine artificial tooth in which the labial surface extends inwardly at the incisal, as well as at the gingival.

FIG. 4 is a sectional view of a posterior tooth formed in accordance with the invention, as seen on the line 4--4 of FIG. 1, and illustrating labial surfaces which slope inwardly from the gingival toward the occlusal.

FIG. 4a illustrates a similar cross-sectional shape of a conventional posterior artificial tooth in which the labial surface thereof is substantially perpendicular to the occlusal plane illustrated by the bottom horizontal phantom line.

FIG. 5 is a plan view of the occlusal surface of the exemplary full arch set of artificial teeth shown in FIG. 1.

FIG. 6 is a front elevation of the full arch set of artificial upper teeth shown in FIG. 1.

FIG. 7 is a side elevation of an exemplary full arch set of upper and lower artificial teeth, including employed in details the present invention and shown in occlusion with respect to each other, said view showing in particular the sloping labial surfaces of the central teeth of the respective sets thereof, which correspond generally to FIG. 2.

FIG. 8 is a front elevation of an exemplary full arch set of lower artificial teeth and illustrating as in FIG. 6 the indented interproximal surfaces adjacent the gingival ends of the teeth.

FIG. 9 is a vertical sectional view of an exemplary set of upper and lower dies in which full arch sets of upper and lower artificial teeth are capable of being molded to have the general characteristics especially shown in FIGS. 6-8.

FIG. 10 is a top plan view of an articulator of a simplified type embodying the principles of the present invention.

FIG. 11 is a side elevation of the articulator shown in FIG. 10, as viewed from the right-hand side thereof, shown in said figure, FIG. 11 also including fragmentarily in phantom, an elevated position of the upper bow of the articulator.

FIG. 12 is a fragmentary vertically sectioned detail of the pivotal support for the upper bow, as seen on the line 12--12 of FIG. 10.

FIG. 13 is another horizontal sectional view, showing a detail of said pivotal means for the upper bow, as seen on the line 13--13 of FIG. 11.

FIG. 14 is a fragmentary vertical sectional view showing details for the support means of the mounting table, shown on the line 14--14 of FIG. 11.

FIG. 15 is a fragmentary horizontal sectional view of the support means shown in 14, but as seen on the line 15--15 of FIG. 11.

FIGS. 16, 17, and 18 respectively show top, side, and bottom views of the support table shown in FIG. 11.

FIG. 19 is a side elevation of a measuring instrument useful in conjunction with the present invention, as shown in the fragmentary portion of a human mouth, illustrated in phantom.

FIG. 20 is a front elevation of the instrument shown in FIG. 19.

FIG. 21 is a transverse sectional view of the instrument shown in FIG. 20, as seen on the line 21--21 thereof.

FIG. 22 is a composite side elevational view of a pair of stepped wedge-like support members used in conjunction with levelling an upper cast with respect to the support table and being disposed between said table and the forward portion of the upper cast selectively in spacings of one millimeter.

FIG. 23 is a top plan view of one of the wedge-like members shown in FIG. 22.

FIGS. 24 and 25 respectively are respective views of different types of alternate support means used in articulators not illustrated in the foregoing views, in lieu of the supporting table actually shown in said views.

FIG. 26 is a side elevation of an exemplary upper gum or jaw of a patient and comprises a dental cast thereof.

FIG. 27 is a perspective view of an exemplary lower cast simulating the lower jaw of a patient.

FIG. 28 is a side view of the upper and lower casts of FIGS. 26 and 27, being joined in operative relationship by means of a jaw-relation bite record, the elements shown respectively in FIGS. 26-28 normally being supplied by a dentist for purposes of utilizing the present invention.

FIG. 29 is a view similar to FIG. 19 and showing the instrument of FIGS. 19 and 20 respectively engaging the lower end of the upper lip and the forward portion of the upper jaw or gum of a patient to provide a required measurement incident to the use of the wedge member shown in FIGS. 22 and 23.

FIGS. 30-41 successively illustrate various steps of the method comprising one of the essential features of the present invention, said steps being described in detail hereinafter in the specification.

FIG. 42 is a perspective view of an exemplary set of artificial upper and lower dentures in which full arch sets of the teeth of the present invention are included.

FIG. 43 depicts tacking of teeth to form a partial denture.

The present invention includes a number of related facets all leading to the common goal of producing satisfactory, reasonably life-like artificial dentures which include full arch unitary upper and lower sets of artificial teeth, thereby resulting primarily in a substantial saving in time to produce the so-called dental "set-ups" which, as such, are then processed by conventional methods into finished dentures. In the foregoing, reference has been made to the great skill and amount of time required to place individual artificial teeth on baseplates and wax set-ups to which aesthetic wax configurations resembling natural gums are included in the "set-ups", and it is in this area of the production of artificial dentures that the present invention provides very substantial advantages.

As is evident from the prior art referred to hereinabove, the use of full arch sets of artificial teeth is not new per se. Attempts have been made by others to commercialize full arch sets of molded artificial teeth, but for the most part, these have been unsuccessful. Possibly a major reason such prior commercial attempts have not been successful has been due to an inability to produce such teeth economically, while retaining acceptable aesthetics with practical adaptability to dental laboratory utilization. The present invention has overcome this difficulty in what is submitted to be a practical and aesthetically acceptable product.

Although the full arch sets of artificial teeth employed in the present invention comprises the subject of another related application, reference to details of such teeth is appropriate herein. One of the advantageous features of the sets of teeth has been the repositioning of many of the teeth from the angles normally chosen for a tooth arrangement for artificial dentures so that the teeth can be mass-produced in rigid molds. This has involved reshaping the teeth to maintain a pleasing aesthetic appearance, as well as realigning them. The anterior teeth, including the central and lateral incisors, for example, have the facial or labial surfaces thereof slanting outward at the incisal edges so the same can be withdrawn from a rigid mold without leaving a parting line on such labial surfaces. The posterior teeth have their facial or buccal surfaces slanting inward toward the occlusal surfaces so they may be withdrawn from another area of the mold without leaving a parting line. The canines are treated in an unusual way by slanting their facial or labial surfaces outwardly at the incisal edges in line with the other anterior teeth, as will now be described in detail relative to the drawings.

Referring to FIG. 1, an exemplary full arch set of artificial teeth is illustrated in top plan view and shows the ridgelap depressions 12 of the four posterior teeth 14 at opposite sides of the set 10, and include first and second molars and first and second bicuspids, together with the six anterior teeth at the intermediate portion of the arch configuration and comprising a pair of central teeth 16, a pair of lateral teeth 18, and a pair of canines 20, all arranged to be molded integrally in rigid molds, such as illustrated in exemplary manner in FIG. 9, and comprising a rigid upper mold 22 and a matching lower mold 24, details of which are described to a greater extent below.

To maintain the arched configuration of the exemplary set of upper teeth 10, stabilizing strut means are attached to the inner surfaces especially of the posterior teeth and comprise a central member 26 from which radial fingers 28 extend somewhat in octopus manner. It will be noted the fingers 28 taper outwardly from the central member 26, the smaller ends of the fingers being connected to the posterior teeth in a manner that may be readily severed therefrom after the stabilizing function of the strut means has ceased, such as when the full arch configuration of teeth has been attached to baseplates or other means described hereinafter in detail.

To provide illustrations of the manner in which the present invention has effected repositioning of many of the teeth from angles normally chosen for a tooth arrangement for an artificial denture, attention is directed to FIG. 2, which is a cross-section taken on the line 2--2 of FIG. 1 and illustrates a vertical section of a central tooth 16, having a ridgelap depression 12 and the facial or labial surface 30 sloping or slanting outward at the incisal edge 32 from the gingival end 34 to facilitate withdrawing the molded teeth from a rigid mold, such as illustrated in exemplary manner in FIG. 9 with respect to the lower mold 24 wherein the molding recess 36 forms the gingival end 34 of the central teeth 16, for example, and in which the surface 38, comprising a series of adjacent molding cavities, forms the labial faces 30 of the central teeth. Preferably, the molding cavities 40 and 41 respectively in the lower and upper molds have parting lines at the incisal ends of the anterior teeth and occlusal surfaces of the posterior teeth.

An exemplary illustration of a substantially conventional artificial central tooth 16' is shown in FIG. 2a and, as shown in FIG. 2, the labial surface 30' thereof is illustrated with reference to ordinate phantom lines at right angles to each other, the vertical line being the reference line with respect to the slanting or sloping of the labial surfaces of the teeth. In FIG. 2a, it will be seen that the labial surface 30' of a central tooth slopes inwardly at both the gingival and incisal ends and would present difficulties in utilizing a single pair of rigid molds in which the parting line is at the incisal ends of the teeth, whereby the exemplary tooth shown in FIG. 2a could not be withdrawn from molds of the type employed to form the exemplary central tooth 16 shown in FIG. 2.

With reference to FIGS. 3 and 3a, it will be seen that in FIG. 3, taken on the line 3--3 of FIG. 1, a canine or so-called "eye tooth" 20 is shown, in which the facial or labial surface 42 slopes outwardly at the incisal end 44 and inwardly at the gingival 46, thus facilitating the molding thereof by rigid molds, as described above with respect to the central tooth 16, shown in FIG. 2. In contrast, the conventional canine tooth 20', shown in FIG. 3a, has an outward or labial surface of curved configuration extending inwardly both at the incisal 44 and gingival 46 and would similarly present difficulties in the type of rigid molds employed in the invention as described above with respect to FIG. 2a.

Turning now to the posterior teeth 14, referring to FIG. 4, which is taken on the line 4--4 of FIG. 1, it will be seen that the outer or buccal surface 48 slopes outwardly at the gingival 50 of posterior tooth 14 and inwardly at the occlusal end 52 to facilitate the removal from the molds 22 and 24, and especially the mold 22 and in which the mold section 54 forms the occlusal surface 52 of the posterior teeth 14. The above-described slope of the buccal surface 48 in FIG. 4 is illustrated with reference to an exemplary phantom ordinate line to illustrate the sloping arrangement. In contrast, referring to FIG. 4a in which a conventional similar posterior tooth 14' is shown, it will be seen that the conventional buccal surface 48' slopes inwardly somewhat at the gingival end 50 and substantially inward at the outer portion of the occlusal surface 52, which arrangement would present difficulties in utilizing molds of the type shown in FIG. 9.

FIG. 5 is an exemplary bottom plan view of a full arch set of upper artificial teeth to illustrate the occlusal and incisal ends of the posterior and anterior teeth, said view being the opposite of that shown in FIG. 1. Referring to FIG. 6, which is a front elevation of the exemplary full arch set of upper artificial teeth, shown in FIGS. 1 and 5, it will be seen in this view that the slope of the buccal surfaces of the posterior teeth 14 is well illustrated and it is to be understood that the shape, and especially the outer labial surfaces of the lateral teeth is substantially similar to that of the canine or cuspid teeth 20. Another important feature of the full arch set of artificial which adapts its use with the invention is also illustrated in FIG. 6 in which it will be seen that pronounced interproximal triangular spaces 56 are illustrated for purposes of effecting desirable aesthetic contours to cause these artificial teeth to closely resemble similar surfaces of natural teeth, at least portions of said interproximal spaces 56, as well as the gingival end portion of the anterior teeth being partially covered by portions of the denture base material in the finished dentures in a manner to resemble natural gums and teeth.

Referring to FIG. 7, it will be seen that there is illustrated therein a full arch set of upper artificial teeth 10 and a full arch set of lower artificial teeth 58, both shown in side elevation and disposed in operative relationship with respect to each other along an occlusal plane 60, shown in phantom. Preferably, the incisal edges of the anterior teeth which are shown at the left-hand end of FIG. 7, and the occlusal surfaces of the posterior teeth shown in the right-hand portion of FIG. 7, commonly abut the occlusal plane 60 and, while the teeth of both types are shaped to closely resemble the outer labial surfaces of the anterior teeth and the outer buccal surfaces of the posterior teeth, the occlusal surfaces of the posterior teeth, in particular, preferably are of the so-called flat plane type in which the occlusal surfaces of opposite teeth are in continuous or nearly continuous contact.

Referring to FIG. 8, in which a front elevation of the full set of artificial lower teeth 58 is illustrated, it will be seen that the corresponding central teeth 62, lateral teeth 64, and canine or cuspid teeth 66 are respectively somewhat narrower than the corresponding teeth of the upper set 10, as shown, for example, in FIG. 6, thereby harmonizing with this characteristic of natural teeth. The groups of four posterior teeth 68, however, as seen from FIG. 7, are not narrower than the corresponding teeth of the upper set 10. In particular, however, it will be seen that interproximal spaces 56 are provided in the lower set of teeth 58 for the same purposes as described above with respect to the corresponding interproximal surfaces of the upper set of teeth 10.

For purposes of simplifying the molding of full arch sets of artificial teeth, it is preferred, in accordance with the invention, that a relatively simple set of cooperating upper and lower molds 22 and 24 be employed. However, it is readily possible to use so-called 3-part molds, embodying principles of the type shown in the prior U.S. Pat. No. 1,547,643 to Clapp, dated July 28, 1925, and in which there is shown a so-called shader mold which is used for purposes of including on the labial or front surfaces of the anterior teeth, a thin layer of more transparent plastic material than that with which the main body of each tooth is formed for purposes of simulating more closely natural teeth which have an outer layer of more transparent plastic which simulates the enamel portion of the tooth, and to this end, the exemplary molds shown in FIG. 9 may be supplemented by a suitable third, shader mold.

For purposes of fabricating the above-described full arch sets of artificial teeth into finished dentures, a special and very simplified type of articulator has been developed, details of which are shown in FIGS. 10-13. Referring especially to FIGS. 10 and 11, the articulator comprises a lower bow or base member 70, which may be disposed upon any suitable supporting surface, such as a counter or bench. It is generally triangular in shape, as seen in FIG. 10, and has a central, somewhat triangular opening 72 formed therein and a securing pin 74 removably extends through aligned openings in the portions of the base 70, which are on either side of the central opening 72, this apparatus being used in conjunction with securing the lower cast or model 76 of a patient's mouth to the base, one exemplary illustration of the same being shown in FIGS. 27 and 28.

Extending upwardly from the rear portion of the base 70, at opposite side thereof, is a pair of support members 78, such as shown in FIGS. 11-15. Said support members have rearwardly extending wing-like extensions 80 and bracing fillets 82, shown in FIGS. 10 and 11, connected to a transverse support bar 84, which is integrally connected at its ends to support members 78, as best shown in FIG. 14. The purpose of the bar 84 is set forth below.

Hingedly connected to the upper ends of support members 78 is an upper bow or member 86 which also has a somewhat triangularly shaped opening 88, formed somewhat centrally thereof and another securing pin 90 extends transversely through aligned openings extending transversely through opposite side portions of the upper bow at either side of the opening 88. The arrangement just described is for purposes of securing to the upper bow 86 an upper cast or model 92 of a patient, one particular example of which is shown in FIGS. 26 and 28. In FIG. 11, the upper bow 86 is shown in full lines in its normal operative position, while in phantom, the same is shown in elevated position. A post 94 is mounted for vertical adjustment within an opening in the forward portion of upper bow or member 86 as clearly shown in FIGS. 10 and 11, adjustment being secured by a thumb screw 96, and is operable to maintain the upper bow 86 in normal substantially horizontal position which is parallel to the base 70. An upper extension 98 is connected axially to the post 94 and is for purposes of holding the upper bow in full-extended, pivotal position, such as shown, for example, in FIGS. 30-36. Similarly, the triangular shape of the extensions 80 on the support members 78 has a lower rearward edge surface 100, by which the articulator may be supported when the surfaces 100 on the opposite support members are disposed on a supporting surface, for any desired purpose.

Although the articulator shown in FIGS. 10-13 is of a very simple nature, especially as compared to other more sophisticated articulators which in particular frequently have elaborate adjustable pivot means, the pivot means of the instant articulator permit at least a limited amount of anterior, posterior, and opposite lateral movements of the upper bow or member with respect to the centric position to permit a desirable amount of milling movements between sets of full arch artificial teeth when respectively supported by the upper bow 86 and base 70, as described in detail hereinafter, as well as pivotal movement of the bows about a horizontal axis. Such limited milling movement is permitted by details shown particularly in FIGS. 12 and 13, and in which the upper ends of the support members 78 are each provided with a threaded opening 102 to receive intermediate threaded portions of threaded thumb screws 104, having knurled knobs 106 on the outer ends thereof and the opposite ends of said screws having a smooth, cylindrical pivot extension 108 of less diameter than the threaded portion 104. Opposite sides of the rear end portion of the upper bow 86 have short elongated recesses 110 of limited length and depth within which the pivot extensions 108 are disposed.

The inner ends of the recesses 110 have a central socket 112, also of limited depth, extending axially inwardly a limited amount for purposes of receiving the terminal end of the pivot extensions 108 when the thumb screws 104 are threaded to the full permitted extent inwardly, whereby a solely pivotal movement about a transverse axis is afforded the upper bow without milling movement. However, by backing off the thumb screws 104 sufficiently until the ends of the extensions 108 are disposed only in the short recesses 110, said limited amount of milling movement of the upper bow with respect to the base or lower bow may be effected, as can be visualized from the length of the recess 110, shown in FIGS. 12 and 13. This amount of movement is adequate to effect a highly useful and practical milling movement.

An important attachment for the articulator comprises a mounting table 114 which is planar and preferably triangular in shape as shown in FIGS. 16 and 18. One surface of the mounting table 114 is provided with a mounting bar or rib 116, which is parallel to the rear edge 118 of mounting table 114 and is disposed a limited distance therefrom for purposes of having the hamular notches 120 of the upper cast 92, see FIG. 26, positioned thereon to facilitate the alignment and height of said cast with the mounting table 114. This situation has need for a measurement which facilitates the full positioning of the upper cast or model on said table employs wedge blocks 122, see FIG. 22. Said blocks have stepped faces arranged predetermined distances apart in elevation, in even or odd increments of two millimeters apart, and in view of there being a pair of such wedges respectively with the stepped surfaces, one has surfaces offset one millimeter with respect to steps on the other, and thereby selectively provide, for example, one millimeter adjustments in the stepped surfaces while using one or the other of the wedge blocks 122, such use being illustrated and described hereinafter relative to additional figures.

The aforementioned measurement referred to immediate a perspective view of a first embodiment of the cabinet hinge of the invention with the arm of the hinge represented as lifted away from the mounting plate,

FIG. 2 is a bottom view of the mounting plate, seen in the direction of the arrow 2 in FIG. 1,

FIG. 3 is a plan view of the spring wire catch element used in the hinge according to FIGS. 1 and 2,

FIG. 4 is a perspective view represented in the same manner as in FIG. 1, of a second embodiment of the cabinet hinge according to the invention,

FIG. 5 is a bottom view of the mounting plate, seen in the direction of the arrow 5 in FIG. 4,

FIG. 6 is a top view of the catch element in the form of a leaf spring, which is used in the hinge according to FIGS. 4 and 5, and

FIG. 7 is a side view of the same catch element seen in the direction of the arrow 7 in FIG. 6.

FIG. 1 shows a cabinet hinge, designated as a whole by the number 10, which is in the form of a so-called four-pivot hinge, whose jamb-related part is the arm 12 , which is coupled by a four-pivot mechanism formed by two links--not shown in detail--to a door-related part in the form of a cup 14 which can be set flush in a mortise in the back of a door. The cup 14 is indicated by broken lines in FIG. 1 since the improvements made according to the invention have no connection with it.

The hinge arm 12 in turn can be fastened adjustably on a mounting plate 16, which can be made of sheet metal by a stamping and pressing method. From opposite sides of an elevated bridge 18 on the mounting plate extend low, wing-like projections 20, each provided with a mounting bore 22. Mounting plates having such lateral mounting wings are also called "wing plates." It is not essential to the invention, however, whether the mounting plate is configured as a wing plate in the manner represented or is of the otherwise commonly used oblong configuration.

The arm 12, which is also made from sheet metal by the stamping and pressing method, has a substantially channel-shaped cross section, whose side walls or flanges 24 are joined together along their upper margins by a web 26. In the end portion located on the left in FIG. 1, two bores 28 and 30 are provided in the flanges 24, which serve for the accommodation of pivot pins on which the eyes of the hinge links forming the four-pivot mechanism are journaled.

On the right in FIG. 1, i.e., in the substantially flat depressed end portion 32 between the flanges 24 there is provided an open-ended slot 34 which serves to receive the threaded shaft of a screw 36 with which the arm 12 is fastened at its cabinet-interior end on the mounting plate 16. The depressed end portion 32 is best provided on its underside with transverse serrations, not shown.

At a distance from the depressed end portion 32 there is provided in the center of the web 26 a tap 38 into which a threaded spindle 40 is threaded, on whose interior end between the flanges 24 there is provided a holding head of enlarged diameter (not shown) connected to the threaded spindle by a narrow stem. Thus, an annular constriction is created between the shaft of the threaded spindle 40 and the holding head. Oblong recesses 42 are formed opposite one another in the inner surfaces of the flanges 42 toward the cabinet-interior end of the arm, and each recess has a vertical abutment 44 at its interior end, i.e., the right end in FIG. 1.

The bridge 18 of the mounting plate 16, which is raised above the wing-like projections 20, has in its upper portion a width corresponding approximately to the clear width between the inner faces of the flanges 24 of the arm 12, so that the arm 12 can be slipped onto the mounting plate 16 such that the flanges 14 straddle the bridge 18. In the end area of the mounting plate 16 remote from the hinge links, i.e., on the right in FIG. 1, there is provided a fixing area 46 which has transverse serrations matching the above-mentioned transverse serrations in the end portion of the arm 12. Approximately in the middle of the fixing area 46 there is provided a tap to accommodate the shaft of the screw 36. At its front end, the bridge 18 is provided with a slot 48 open at the hinge link end, whose width is such that the stem between the holding head and the actual threaded portion of the above-mentioned threaded spindle 40 can be fitted into it. The arm 12 is mounted on the mounting plate 16 by pushing it with its slot 34 under the head of the previously loosened screw 36 and at the same time inserting the stem joining the holding head to the threaded shaft of the threaded spindle 40 into the slot 48. It is clear that the arm 12 can be fastened at selectable positions on the mounting plate 16 within the length of the slot 34 and slot 48, the arm being then secured against longitudinal displacement by tightening the screw 36 which clamps the transverse serrations on the underside of the end portion 32 against the transverse serrations in the fixing area 46. It is furthermore apparent that the distance between the front end, i.e., the hinge-joint end, of the arm 12 and the mounting plate surface formed by the base of the wing projections 20 and contacting an associated jamb can be varied by varying the depth to which the threaded spindle 40 is driven into the tap 38. The arm 12 is therefore adjustable in two coordinate directions, namely longitudinally and at right angles thereto, i.e., approximately perpendicularly to the surface of the jamb wall.

As it can be seen from FIG. 2, showing the mounting plate 16 from its underside, a catch element 50, in the form of a steel hairpin spring, also represented separately in FIG. 3, is disposed in the cavity formed in mounting plate 16 by the bridge 18. The legs 52 and 54 of the spring are of unequal length and are joined together integrally by an arcuate section 56, the transitions between the arcuate section 56 and the legs 52 and 54 being bent sharply in the manner seen at 58 in FIG. 3, so that they can snap into associated openings 60 (FIG. 1) in the side walls of the bridge 18 of the mounting plate 16. The longer leg 54 also passes through a slanting slot 62 (FIG. 1) in the end wall 64 at the cabinet-interior end of the bridge, its protruding end forming a handle which can be displaced in the direction of the slanting slot 62. Normally the leg is situated at the upper right end of the slot as seen in FIG. 1, and can be shifted downward and to the left. The catch element 50 is thus rocked downwardly as a whole, the rocking axis being formed by the sharply bent transitions 58 held in the openings 60. In this rocking movement, the shorter leg 52 is also swung downwardly. This leg 52, which reaches outwardly at an angle into an opening 66 in a side wall of the bridge 18 of the mounting plate, and whose free end, pointing backward, protrudes slightly from the side wall, forms with its rearwardly pointing extremity an abutment 68 which, when the arm 12 is pushed onto the mounting plate 16, cooperates with the catch abutment 44 such that, as the arm is pushed on, the end section of the leg 52 is initially forced back into the opening 66 by the side wall 24, until the catch abutment 44 of the recess 42 has been pushed past the catch 68. Then the end section of leg 52 snaps into the recess 42 and the arm 12 is secured against withdrawal from the mounting plate. The position of the abutments 44 on the inside surfaces of the flanges 24 of the arm 12 on the one hand and of the abutment 68 of the catch element 50 on the other is selected such that, when the arm is pushed onto the mounting plate, they come into catching engagement just as the shaft of the screw 36 enters the mouth of the slot 34 and the stem on the threaded spindle 40 enters the mouth of the slot 48.

It is clear that the catching engagement can be released without further backing out of the screw 36, by pressing the protruding end of leg 54 in slot 62 diagonally downward; the rocking movement is thus transmitted to the leg 52 and the abutment 68 formed on the latter is turned downwardly out of engagement with the abutment 42. The leg 54, which is normally already under bias at the upper end of the slot 62 is additionally flexed downward upon the downward pressure on account of the slant of the slot. The leg 54 therefore strives to snap back after release, and it will be guided back along the lower slanting edge of slot 62, upwardly at an angle, to the starting position.

In FIGS. 4 to 7 there is shown a cabinet hinge 10' that is a modification of the one described above, and differs from hinge 10 only with regard to the configuration and arrangement of the catch element in the mounting plate 16. Therefore only these modifications will be described, while otherwise it is sufficient to refer to the above description, inasmuch as equivalent parts of hinges 10 and 10' are given the same reference numbers in the drawing.

The catch element 70 is in the form of the leaf spring shown in FIGS. 6 and 7, and has at its end on the left in the drawing the chamfered end tabs 72 projecting outwardly from the two longitudinal edges; the tabs 72 are snapped into mating slots 74 in the side walls of the bridge 18 of the mounting plate and hold the leaf springs tightly at this end within the bridge 18. The leaf spring is divided by a central slot 76 extending over part of its length into two parallel tongues 78a and 78b, the slot 76 being provided mainly for the purpose of permitting the insertion of the free end of the shaft of the screw 36 and of any other screws driven through the center of the bridge 18. Furthermore, the lateral elasticity of these tongues, which is created by the division of the leaf spring, also enables the tabs 72 to snap into the slots 74. In the rearward end area the two tongues 78a and 78b unite to form an integral section 78 of the leaf spring, which narrows to the end section 80 which passes through an opening 82 in the rear end wall 64 of the bridge and forms the handle of the catch element 70.

In the area of the cutouts 66 provided in this case in the confronting side walls of the bridge 18, the catch element 70 has two tab-like projections 84 which are chamfered at their edges and which pass each through its corresponding cutout 66 into the path of the flanges 24 of the arm 12 as the arm is installed on the bridge 18. By the configuration shown especially in FIG. 7, in which the projections 84 are disposed in an upwardly slanting section of the leaf spring tongues 78a and 78b, the projections 84 also slant upwardly, so that their upper part forms a ramp for the leading end of the arm 12 as it is being installed on the mounting plate, which forces the projections downwardly within the cutouts 66 until the recess 42 passes over the projections, whereupon the latter snap into the recess 42. The edges 86 of the tab-like projections 84 then form with the locking edges 44 of the arm recess 42 effective locking edges of the catch element 70 for securing the arm 12 against withdrawal from the mounting plate 16.

It is easily seen that the engagement of the locking edges 44 and 86, which secures the arm on the mounting plate against accidental withdrawal, can be deliberately released by pressing down the end section of the catch element 70 in the opening 82, thus bringing the tab-like projections 84 below the bottom edges of the flanges 24 of the arm 12.

The fastening of the catch element within the bridge section 18 of the mounting plate 16 can, of course, be performed in some other manner, e.g., by riveting its hinge-link end to the bridge 18. It is furthermore to be noted that the snap locking according to the invention is not limited to the "wing plates" especially described, but can be applied generally in cases in which a hinge arm at least partially straddling the mounting plate is pushed longitudinally onto this mounting plate during assembly. Instead of the mounting plate 16 produced from sheet metal by the stamping and pressing method, the mounting plate, as well as the hinge arm, can also be made of metal, e.g., from zinc alloy (Zamak) by pressure casting.