US 3861867 A
A tray for oven-firing porcelain dental bridges and like dental appliances comprises a support plate having a plurality of threaded openings transversely therethrough. A plurality of appliance-supporting pegs having threaded bases are mountable in vertically adjustable threaded engagement with selected ones of the openings.
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Description (OCR text may contain errors)
United States Patent [191 [111 3,861,867 ()uhl Jan. 21, 1975  TRAY FOR OVEN-FIRING PORCELAIN 1,963,242 6/1934 Nelson 432/259 DENTAL BRIDGES AND LIKE DENTAL [619L939 APPLIANCES opera r 3,778,224 12/1973 Duffner 432/258  Inventor: Kenneth R. Ouhl, 167 E.. l33rd SL,
Tacoma wash 98445 Primary Examiner-William T. Dixson, Jr.  Filed: Aug. 29, 1973 Attorney, Agent, or Firm-Eugene D. Farley  Appl. No.: 392,616
.  ABSTRACT U-S. a
A tray for oven firing porcelain dental bridges and 206/72, 211/13 214/18 269/53 dental appliances comprises a support plate having a CL pl rality of threaded penings n-ansversely there-  Field of Search 206/72, 63.5; 211/13; through A plurality f appliance supportipg pegs 3, 269/53, 432/258, 259, 253, 261 ing threaded bases are mountable in vertically ad ust-  R f Ct d able threaded engagement with selected ones of the e erences l e openings UNITED STATES PATENTS 1,530,479 3/1925 Carlson 432/259 5 Clam, 2 Drawmg F'gures 5O 4 r 1 ]ll I) 52 50 U I W I TRAY FOR OVEN-FIRING PORCELAIN DENTAL BRIDGES AND LIKE DENTAL APPLIANCES BACKGROUND OF THE INVENTION This invention relates to apparatus for use in the manufacture of prosthetic dental appliances. More particularly, the invention pertains to a tray for supporting porcelain dental bridges and like dental appliances during the oven-firing of the same.
In the manufacture of dental bridges, dental crowns, and like prosthetic dental devices, an impression first is made of the teeth to which the device is to be applied. The impression in turn is employed in the manufacture of caps for the teeth. The caps are made of ceramic gold or other suitable alloy having a melting point high enough to withstand firing in a ceramic oven.
A porcelain-forming paste then is applied to the metal caps and worked into thedesired shape. The resulting composite assembly of paste and underlying metal caps is placed in an oven and fired at a temperature at which the paste is converted into a hard, finished porcelain product which is strongly adherent to the underlying metal base and together therewith forms the prosthetic tooth assembly which is cemented to the residual living tooth structure.
In the execution of this technique, use is made of a tray on which the device to be fired is placed and on which it is supported in appropriate position by means of positioning pegs one end of which engages the tray and the other end of which engages the prosthetic device.
Use of the tray-peg combination is complicated by the fact that the various prosthetic devices vary greatly from each other in the number of teeth which they contain, the size and shape of the teeth, the contour of the teeth, their linear relation to each other as they are supported side by side on the metal underlayment, and in particular their planar relationship to each other. In other words, some of the teeth lie on vertical planes which are different from the vertical planes in which their companion teeth lie.
Nevertheless, it is important for the success of the final operation that during firing the teeth all be uniformly supported, no matter what their spatial relation to each other may be. This is true, since if certain of the teeth are not adequately supported, they will sag during the firing operation and the resulting prosthetic dental appliance will be formed imperfectly.
It accordingly is the general object of the present invention to provide a tray for use in oven-firing dental bridges, crowns, tooth caps, and like dental prosthetic appliances which will support the appliances uniformly and efficiently during the firing operation even though the appliances differ widely from each other in size, shape, number of teeth, and the planar disposition of the teeth.
It is a further object of the present invention to provide a tray for oven-firing porcelain dental prosthetic devices which is quickly and easily assembled, adaptable for use with conventional oven-firing support pegs, readily adaptable to support the diverse configurations which characterize various dental devices, nondeformable when subjected to the intense heat of the firing oven, easily adjustable over a long period of use, and of relatively simple, inexpensive construction.
GENERAL STATEMENT OF THE INVENTION In accordance with the present invention, the foregoing and other objects are achieved by the provision of a tray for oven-firing porcelain dental prosthetic appliances which comprises a support plate having a plurality of threaded openings transversely therethrough. The openings are arranged peripherally in spaced relation to each other.
A plurality of appliance-supporting pegs having threaded bases are mountable in vertically adjustable threaded engagement with selected ones of the openings through the plate. In a preferred and illustrated form of the invention the pegs are in two parts: a threaded base part, and a tooth-engaging peg part. The base part has a vertical socket and the peg part has a lower shaft porition dimensioned for gravity seating in the socket.
Thus, in use, the base of the peg may be threaded into a selected one of the threaded openings through the plate and adjusted to the necessary height. The bases of the companion pegs are similarly engaged with selected openings of the plate. The unfired dental appliance then is mounted on the pegs in a perfectly supported condition, ready for firing.
THE DRAWINGS FIG. 1 is a view in top perspective of the hereindescribed tray for oven-firing porcelain dental prosthetic devices in assembled, use condition, illustrated in its application to the support of a piece of dental bridge work to be oven-fired.
FIG. 2 is an enlarged detail view of a support peg combination employed in the tray assembly of FIG. 1.
DESCRIPTION OF A PREFERRED EMBODIMENT As viewed in FIG. I, the tray assembly for oven-firing porcelain dental prosthetic appliances comprises in combination a support plate, indicated generally at 10, and a peg unit which comprises a base component indicated generally at 12, and a peg component indicated in two different forms at 14 and respectively. The assembly is used to support in oven-firing condition a prosthetic dental appliance comprising the dental bridge indicated generally at 16.
In the above assembly, the support plate comprises a plate 20 fabricated from a suitable alloy resistant to the effects of high temperature. It preferably is contoured in the shape of a truncated triangle. It is supported on legs 21.
A plurality of transversely oriented threaded openings 22 are disposed peripherally in spaced arrangement about the surface of the plate. A central opening 24 is provided for ease of manipulation of the plate with tongs and other tools employed in handling it before and after the firing operation. The central opening preferably is arranged symmetrically with respect to the peripheral contour of the plate.
Pegs 14, 14a are conventional. They may be supplied in a variety of shapes, sizes and arrangements in order to perform indicated functions. Usual forms are the pointed peg indicated at 14, and the extension arm peg indicated at 14a. Additionally, however, pegs may be provided as flat top pegs and inlay pegs, not illustrated, as well as in other contours.
The pegs are employed in various combinations to suit particular requirements. For example where a full mouth restoration is being fired, pointed pegs may be employed to support the tooth components which lie outwardly of the support plate. Obviously, they may be swung at any desired or necessary angle.
Pointed peg 14 includes a spur portion 26, a shaft portion 28 and a medial supporting flange 30.
Extension arm peg 14a comprises a spur portion 32, a laterally extending arm portion 34, and a shaft portion 36.
In both forms of pegs, the spur portions, 26 and 32 respectively, serve the function of entering an opening in the dental appliance for releasably securing and supporting the same during its firing. Lateral arm portion which teeth are composed.
Intermediate teeth 46 comprise an aggregate 52 of ceramic paste of the same nature, formed into the shape of a tooth. They are not individually supported, but are integrated with the ceramic bodies of the adjoining teeth.
ln mounting bridge assembly 16 on the hereindesdribed firing tray, the bridge is arranged in an appropriate working position above the tray. An appropriate number of pointed and extension arm pegs are selected, in the illustration four of the former and one of 34 of the extension arm peg 14a serves the function of locating the spur properly with respect to the appliance. Shaft portions 28, 36, respectively, of both forms of pegs serve to mount the pegs on the support plate.
In one form of the invention, not illustrated, these functions may be accomplished by threading the shaft portion of the peg so that it will engage the threads of a selected one of threaded openings 22 through the support plate. Preferably, however, a peg base 12 is provided as a separate component.
This component comprises an externally threaded sleeve 38 dimensioned for reception in threaded openings 22. The sleeve is formed with a bore or socket 40 dimensioned to receive shaft portions 28, 36 respectively of pegs 14, 14a. Socket 40 is dimensioned for a bearing fit with the shafts. Accordingly arm 34 of extension arm peg l4a may be adjusted angularly to any desired position.
Means also is provided for adjusting the vertical position of peg base 12 to the desired plane. In the illustrated form of the invention, such means comprises one or a plurality of slots 42 arranged radially on either the top or bottom of the peg base and dimensioned to fit the blade of a turning tool such as a screw driver.
The manner of use of the hereindescribed tray assembly as applied to the support of a dental bridge 16 including eight irregularly disposed tooth components is illustrated in FIG. 1.
As seen in that figure, the dental bridge includes a plurality of anchor teeth 44 and a plurality of intermediate supported teeth 46.
Each of anchor teeth 44 comprises a tooth cap 48 made of ceramic gold alloy and having a pocket dimensioned to fit over a live anchor tooth. The alloy cap supports a tooth portion 50 made of ceramic paste which upon firing is converted to a hard porcelain product closely resembling in appearance the substance of the latter. The bases 12 for the pegs are screwed into the selected ones of openings 22 in support plate 20. The bases are adjusted to the elevation required to maintain the bridge uniformly supported when it is superimposed on the tray, with the peg shafts received in sockets 40 of the bases and the peg portions penetrating the openings in the support teeth of the bridge.
The bridge then may be introduced into the firing oven and fired at elevated temperatures without danger of sagging or malformation caused by heat softening of its components.
Having thus described my invention in preferred embodiments, I claim as new and desire to protect by Letters Patent:
1. A tray for oven firing porcelain dental bridges and like dental appliances comprising in combination:
a. a support plate,
b. a plurality of threaded openings transversely through the plate, arranged peripherally in spaced relationto each other and c. a plurality of appliance-supporting pegs having threaded bases mountable in vertically adjustable threaded engagement with selected ones of the openings.
2. The tray of claim 1 wherein the plate in plan has the contour of a truncated triangle.
3. The tray of claim 1 wherein the plate has therethrough a central opening contoured in the shape of a truncated triangle symmetrically arranged in the center of the plate.
4. The tray of claim 1 wherein the peg has a lower shaft portion and an upper spur portion and the peg base has a vertical socket dimensioned for gravity seating of the shaft portion of the peg.
5. The tray' of claim 4 wherein the peg base has on one of its ends at least one radially disposed slot for reception of a turning tool.