US2327548A - Jacket crown - Google Patents

Description

Aug.2 4,1943.` A. J. #EAM/IM 2,327,548

JACKET CROWN Filed sept. 5, 1941 VA A . Patented Aeg. 24, 1943 i. UNlTEo i STATES PATENT; o.-FEIC;E;-;

JACKET cnowN n Abram J, Pearlman, chicago, in.

Application september 5, 1941, serial n1409313 f s-claims. (o1. :az- 12) The present invention relatesto dental vprocesses and' particularly to the` crowning of teeth. The main object of the` invention is. to, provide anew andimprovedjacket crown that may be made in stock sizes, shapes, colors, etc. with the proper. surface linesi and' facets to". adequately match natural teeth and applied by the dentist without using auxiliary metal linings and the like.

It is also an object of. the present invention to improve the'process ofv applying. jacket crowns to. teeth.` This invention enables al dentist to produce an inexpensive and natural reproduction o a normal tooth to replace a badly broken down and decayed tooth, in a simple manner, by selecting a suitable ready made stock 1crown which can be. easily adapted to the remaining tooth stump. n

Other detailed objects and advantages offthe invention will appear from the-following description and the drawing disclosing the preferred form of the invention. It should be4 `understood howeverthat' the description and' drawing, are illustrative only and are not intended toA limit the invention except insofarasit is limitedfby the appended claims.

In the k'drawing--` Fig. l is a labialV view of a tooth illustrating generally the. preparation of` a Atooth to be crowned;

Fig.' 2V is a view of the widest part of the stumppreparation;`

` Fig. 3 is ra view illustrating the measurement of a stock jacket crownv to determineitsfadaptability to the prepared toot-h stump; n

Fig. ll isa fsectional View ofllthe crown Figs. 5 and, 6 l are i sectional views illustrating the iitting of' the selected 'crown upon the tooth stump.

In order that the nature of my invention may be more clearly understood I will'describe one method of preparing and crowning `a tooth in connection with the accompanying drawing. The tooth to be crowned, illustrated in Fig. 1, consists of a root portion I0 and an exposed portion Il (shown only in dotted lines in Fig. l). The enillustrating the'measuement element;

amel is rst removed down substantially to the originalI surface at the gingival section. Theresulting appearance ofthe prepared toothissub.- stantially as shown inFig. l'of the drawing. f

The next step in the preparation ofthe tooth for crowning consists in measuring-the.` circumference and shape of the prepared tooth stump l2. As illustrated i-n Fig. 2, a wireloop, I-3 is ap-` plied tothe stump. l2, `the loop being fixed in a dentimeter or ordinary loroach holder lll.` The wire loop, t3 is, tightened until the wire engages loosely with the. root surfaces. of the tooth. The wire loop is then carefully adjusted.' so thatitis even with or slightly under ,the/gum margin at the widest section o the tooth,` and is then twisted tight about ther-Widest section. The `wire is then carefully removed so asv to retain the circumferentialshape'lof theftooth stump at its wid# est cross section. n

aving. made the measurement the dentisty is now ready to Aprepare and attach a crown. The present` invention is particularly advantageous in; enahlingjthedentist to4 provide a` proper jacket crown for application to a tooth prepared Iin the foregoing manner. Heretofore it has generally been the practiceior the dentist totake impressions and thennmakea crown or have someone make a crownto iii-, a particular stump. Where .this has not been theI practice stock crowns are used butsuchstock crowns are of porcelain combined with someY other material such as gold or a gold alloy sleeve.A Heretofore, so far as` I am aware, it has notbeen possible to directly lt a stock` crown .upon ait'ooth stump without the necessity of using eithermametal lining andre- 'in'forcement for the porcelain.

In accordance with my preferred practice;I make theY crownsfrom` a. material having a cer]- tain amount of elasticity,f with the necessary VBrinell hardness and tensile strength. I have found that the acrylic resins are particularly satisfactory for my purpose although other resins or vacrylic resins in combination with other substances having the desired characteristics may also be used. For example, Polystyrene and methacrylate resin are satisfactory. Their Brinn ell hardness and tensile strength, when properly prepared, compare favorably with the better gold alloys. .A plastic of one Iof these materials may be given a Brinell hardness of 40 to 60 with a tensile strength of 15,000 to 30,000 pounds. These materials are easy to nish and polish, are nonconductors of electricity, and have low thermal conductivity.

The crown itself is preferably molded in quantities of stock shapes, sizes and colors to t the width and length (preferably a slightly larger all over dimension, selected so as to establish proper 1 contact with the adjacent teeth). is placed on the base of the selected crown so that the anatomical form as indicated by the wire loop will remain within the limit of the surface I at the open end of the crown l5 (see Figs. 3 and 4). loop should .be Placed as close as possibleto the externallabial or buccal border of the ystock crown and in this position :the loop is outlined on the surface. IS by 'etching on the plastic or byrneans of articulating paper or pastel The dentist then proceeds to ream out the chamber I'l of the crown to, the outline of the loop.y Care must be exercised not to extend beyond the border of the outline. The crown material is readily worked down so that it can be seated on the tooth stump with considerable accuracy and brought intov proper relation with the adjacent teeth. 'Ihe dentist of course may use articulatingpaste to indicate the high spots which should be eliminated in fitting the crown onto the too-th stump. This fitting is illustrated best in Fig. 5 where it will be noted that the inner surface I9 of the crown l5 has been worked down so as to fit the crown snugly upon the tooth'stump 12. The external wall I8 of the crown is then reduced around the gingival portion so that no overhang remains below the gum line. That is, the tapering is lcarried right out to a junction with theftooth surface at the gingival section (see Fig. 6).

'Proper contacts are established with the adjacent teeth andthe top [of the crown is ground in to fit the opposing teeth as to bite and established height; The crown is then polished by slight bufling with a soft wheel andis cemented directly to the tooth stump with a suitable cementing substance. l

From the foregoing description it is believed to be clear that I have provided an improvement in the crowning of teeth and in jacket crowns whereby a tooth stump may be crowned with a single material jacket crown that affords anhigh degree of protection. The crown is particularly The wire loop The labial or buccal part of the good because of its 10W heat conductivity, its nonconductivity of electrical currents, and the absence of any metallic linings or other fastening means of metal. be tapered to a thin nishing edge at the gingival section of the tooth permits the retention of a. heavy base for the tooth stump and eliminates the necessity of providing a shoulder on the tooth stump.

claim as new and desire to secure by Letters Patent is:

1. The method of crowninga tapered stump having its greatest cross sectional area at the gingival section meeting the original tooth surface without a shoulder which comprises, providing a tooth simulating jacket crown with a tapered chamber in one end and a relatively wide flat surface around said chamber, marking the contour of the base of the tapered stump on said surface and fastening the crown to said stump so as to cover the entire exposed area of the tooth stump by reaming out the chamber within the crownto the marked contour and cementing the jacket crown directly to the stump.

2. The method of crowning a tapered stump having its greatest cross sectional area atthe gingivalsection meeting the` original tooth surface without a shoulder which comprises, providingl a tooth simulating jacket crown witha tapered chamber in one end and a relatively wide flat surface around said chamber, markingfthe contour of the base ofthe tapered stump on said surface and fastening the crown to said stump so as to cover the entire exposed area of the tooth stump by reaming out the chamber within theY crown to the marked contour and cementing the jacket crown directly `to the stump, and cutting down the outer surface ofthe crown to meet the original too-th surface at the gingival section. l

3. A jacket crown for vdirect and permanent application to a tapered tooth stump. said crown having a recess extending into lit from one end, the crown having its outer surface formed to vsimulate a natural tooth, saidcrown'being comlposed of high tensile strength resin materialv of low heat'conductivity, substantially 4a non-conductor of electricity and non-frangible, said crown I having a thick wall terminating in a flat surface about the open end of .they recess sufcient to encompass, between the recess and the outer pe# riphery, normal variations in size and shape of tooth stumps.' whereby fthe crown recess may be enlarged to fit a stumpA and the peripherymay'be cut down to a smooth meeting with the original tooth surface at the gingivalsection. ,v A

l ABRAM J. .PEARLMANl The fact that the crown may` Having thus ydescribedEmy-invention, what I

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