US2672687A

US2672687A - Dental prosthesis

Info

Publication number: US2672687A
Application number: US126766A
Authority: US
Inventors: Dahl Gustav Sven Adolf; Almer Sven Bertil
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-11-15
Filing date: 1949-11-12
Publication date: 1954-03-23
Anticipated expiration: 1971-03-23

Description

.Mawh 1954 G. s. A. DAHL ETAL DENTAL paosmzszs Filed NOV. 12, 1949 Wo MV- Lm QM;

44 Cw g mnw Patented Mar. 23, 1954 UN ITE D STATES PATENT OFFICE;

' Gustav -Sventldolf Dahl and Sven BertilAlmr, Stockholm, Sweden Application November-lfl, 1949,1LSerialNo'. 126F66 Claimsmriority, application Sweden November 15, .1948.

(Cli 32 10) 5 Claims.

.The present inventionrelates. to .dental prostheses; and more particularlyflto those which consistofa supporting bodyof metal, generally'gold, and'ajfacing .or. a similar toothimitation of an artificial material, i previously usually porcelain.

butJnoWadays alsoartificial resin, such as acrylic resin,'the metallic'support being intended to form an attachmentwithin or at the sideof the existingteeth and thefacingbeingadapted to give the prosthesis .a naturalappearance, especially.

on the outwards directed or otherwise visible part oftthe prosthesis; "Examples of prostheses of .the presentkind are particularly so-called bridges where the prosthesis is suspended to adjacent.

teeth, and pivot teeth. where the prosthesis is an-. chored in a remaining natural root of a tooth Iii-"hitherto occurring typ esflof prostheses of the present kind the metallicbody'is usually provided with'projections which. accurately fit" in corre sponding recesses provided in the facing; These connectingxmembers. have been so designed that the" facing could be applied "to" the supporting body in auuitedefinitedirection only, which has been considered to be necessary withthe previously available possibilities of. obtaining a firm andrigid connection between'theseparts. For.

thejunction there has been employed; besides the purely'mechanical anchoring "means, a binding agent OfIOI'dll'lBiIYfklIId, e. g. phosphate cement, whetherthe' facing has beenmadeof porcelain or of'artificial resin. Incase of artificial resin prostheses :ithas,.moreover, been usual to producethe prosthesis by "moulding the facing from the artificial resin compound and pressing it directly ,onto the metallic support. and then subjectingit to final treatment, usually an operationof polymerization, at an elevated temperature.

However, it has been :found that, inconnection withdental prostheses consisting ofmetallic body with retentions and facing or similartooth imitation..made of soluble artificiahresin preferably acrylicresin, it is. possible tolbring about. a much easier method ofapplying thefacing and to-ob tain .at thesame time; a. considerably better connectionbetween .the parts, .,:'j.f'. the facing tor. the likel'isrsecuredto the, metallic. body byrmeans. of I a -binding agent; meltedtogether with the facing by;means .of a-solvent or'a plasticizer; such as ethyl acetate or preferably chloroform,-said bindingagent being suitably produced onathebasisof artificiaL-resin preferably; from theisame; artifiw ciahresin,basalsmateriallas the facing; Prefene ably the inside of the facing is so designed that the facing may, notwithstanding. the. retentions. of the metallic body, be applied into its finallposia tion onto the, metallic body from a pluralitymf diiferent directions.

final position has been reached orhasbeennearlyi reached.

The invention will be more.closely.described, in the following with reference to some. realiza=. tions shown in the accompanying drawingmerelyi as illustrative examples and not inla limiting sense, and in addition comparisonsare madeiwithj previously known arrangements intended for the. same purpose.

In the drawing; Figures 1' to 5.show embodi ments according to the-invention, Figures 1. and .4 showing facings disposed on bridges, Figures, 2.

and 5 showing the facings proper, as viewed from the inside, and Figure 3 shows the facinggof Figures 1 and 2 adapted fora pivot tooth.

According to the present invention there is emplayed a binding agent which bindsfirmlyito the facing, preferably one having substantially. the

same elastic propertiesas the facing material,

and, as a result; newpromising possibilities present themselves: A preferred binding agent consists-of a syntheticresin polymer, suitably ,of. acrylic resin, such as polymethyl metha.crylate,.

dissolved by or at leastswelled up withQa solvent amine in. appropriate concentrations;

will. have imperceptibly passed over; intimately and: without any seam, into the material-pr ttie facing, a .especially ifithe facing material' 'and the binding. agent consist of the same kind =of= synthetic resin: Since the: binding lagent thus maybe. said toform an integrating part-of the facing body and is entirely. plastic during the applica tion of .the' facing to the supporting body and thus :canpenetrateinto all retentionsandirregwlaritiesa :thereimtthe facingwwill after the setting v of thezbinding;agent'ibelimmovablyfandIfirml-y ari chored in the supporting body.

The. facing, is. suitably? so; shaped that during the application .it is movable substantially parallel to the main stretch. of. its. contact with the metallic bodyatleast untillits;

Although acrylic acid has been particularly mentioned as a basic substance for a synthetic resin for the present purpose, it will be understood that many other plastics are useful than those derived therefrom. Thus polystyrene and polyvinylplastics, such as polyvinylchlorideacetate may be used. Apart from monomerpolymermixtures and chloroform already mentioned, also acetone, methyl ethyl ketone, ethyl acetate and ethylene dichloride as well as, possibly, toluene, benzene, butyl acetate and amyl acetate may come in consideration. Lower alcohols, such as ethyl, methyl and butyl alcohol, and carbon tetrachloride, may have some value.

Through this new method of applying a facing it is, on the other hand, rendered possible to make the facing with greater freedom so that guide and anchoring members of the known kind may be dispensed with and the facing may in lieu thereof be so shaped that, at least during the very greatest part of'the application to the supporting body, it may be applied from more or less different directions.

The facing H shown in Figures 1 and 2 is, on its front side l2, shaped as a natural tooth and has at one end a root tip I3, which is intended for the cavity after an extracted tooth. On the backside, the facing has at the top a shoulder M which should be shaped in accordance with the natural tooth. Between the root tip it and the shoulder M the facing is provided with a number of grooves or slots and ground-off portions which, in the instance shown, leave two elevations 15. Between these there is a vertical groove l6, and between the elevations and the root tip there is a horizontal groove or slot ll. These grooves or slots are at right angles to each other and are so disposed as to form a T. Laterally of the elevations the facing is provided with recesses l8.

The supporting body, which in Figure 1 consists of a bridge 2|, is provided with projections or lamellae, namely 22 extending into the horizontal groove l1 and 23 extending into the ver tical groove l6. Moreover, the bridge may have lamellae corresponding to the recesses Hi. In certain places or everywhere on its surface, the supporting body has retentions 24 which preferably are wider inwards than at the mouths and may consist of projecting flanges or pricks or the like.

In Figures 4 and another embodiment is i1- lustrated in which the bridge 2| has projecting beams or lamellae 23 provided with trough-holes 40 into which the binding agent can penetrate to form supporting and anchoring beams. The tip I3 is bevelled as indicated at ll for engaging smoothly the upstanding collar 42 of the bridge. The bridge has three parallel lamellae 23 and as shown in Figure 5 the facing has three corresponding grooves or slots It in the cavity 53 over which the root tip l3 and the crown tip it stick out to form seats 44 and 45 for the bridge.

Although the grooves or slots IE5 and I! may widen somewhat inwards, this is not at all necessary but on the contrary disadvantageous, and

it is most often preferable if they taper inwards. However, these grooves should conform rather closely with the corresponding projections or

lamellae

22 and 23, respectively, on the supporting body in order that the requisite quantity of binding agent be small. Nevertheless, it is evident that the grooves or slots may be so shaped as to permit that the facing ll need not be applied in such a definite direction as in the prior art devices, but far more renders possible an extensive freedom in the choice of direction of application. However, the innermost portions of the grooves and the outermost edges of the supporting body should fit accurately in each other so that the final position becomes fixed.

Figure 6 shows how a facing according to Fig ures 1 and 2 may, by merely grinding-off the root tip it, be converted into a facing adapted for a pivot tooth. The facing of Figures 4 and 5 may, of course, be treated analogously. The contour 26 of the root tip and its inner surface 2'! are represented in Figure 3 by means of dot and dash lines. The supporting body 30 is, in the same way as the supporting body 2i, provided with retentions 31 but extends, in contrast to the body 2!, farther downwardly towards the root portion, and also there it may have retentions. In relation to the facing, the body 30 is in other respects shaped substantially identically with the bridge body 2| so that the same facing may fit a bridge as well as a pivot.

The supporting body 30 is secured, in accordance with conventional dental practice, in the tooth root 32 by means of a pivot 33. A mantle 3a is tightly secured on the upper edge of the root in the usual manner.

Through the invention it is also made possible to provide the supporting body with reinforcing beams so that its strength is increased, with a resultant considerable saving of material.

The grooves or slots l6 and I! are preferably at an angle to each other, as shown in Figure 2, but the angle may be of a magnitude other than The grooves may also be disposed in a fishbone like manner or crosswise. Further they may depart from the rectilinear form and be, for instance, circular, semicircular or annular. It is essential, however, that they permit of an application in at least some directions differing more or less from each other. They should also afford supporting surfaces for vertical as well as horizontal pressures.

What is claimed is:

l. A dental prosthesis, comprising, in combination, an elongated tooth member of artificial resin having a front face and a rear face; a cut-out arranged in said rear face of said elongated tooth member and having a top and bottom face being spaced apart from the top and bottom edges, respectively, of said elongated tooth member and a lateral engagement face provided with at least two elongated recesses therein arranged substantially normally to said lateral engagement face of said cut-out and extending parallel to the axis of said elongated tooth member substantially from the top to the bottom face of said cut-out; a supporting metal body including a backing portion fitting into said cut-out of said elongated tooth member and having a top and bottom edge and a frontal engagement face located between said edges and engaging said lateral engagemerit face of said cut-out; at least two projecting lamellae on said frontal engagement face of said backing portion projecting substantially normally to said frontal engagement face, extending substantially from said top edge to bottom edge of said backing portion and being shaped for entering said elongated recesses in said lateral engagement face of said cut-out whereby said backing portion of said supporting body and said lamellae thereon can be brought to engagement with said cut-out and elongatedrecesses, respecmotionithereofbeing.substantiallynormalz to rsaid engagementl-faces of. saidarelong'ated tooth mem ber: and said backing lportiomi andrbinder' means retainingxsaid hackingportioniaandi said ila mellae thereon inlsaid cute.out v.andrelengated recesses, respectivelmfof..saidelongated .itOOth. member;

2. A dental prosthesis, comprising, in combination, an elongated tooth member of artificial resin having a front face and a rear face and having at least two elongated recesses in said rear face arranged substantially normally to said rear face and extending parallel to the axis of said elongated tooth member and spaced from the engaging said rear face of said elongated tooth member; at least two projecting lamellae on said frontal engagement face of said backing portion projecting substantially normally to said frontal engagement face, extending said top edge to said bottom ing portion and being shaped for entering said elongated recesses in said rear face of said elongated tooth member whereby said lamellae on said backing portion of said supporting body can be brought to engagement with said elongated recesses in the rear face of said elongated tooth member only by a motion thereof being substantially normal to said rear face of said facing member; and binder means retaining said lamellae in said elongated recesses so as to firmly attach said elongated tooth member to said backing portion of said supporting body.

3. A dental prosthesis, comprising, in combination, an elongated tooth member having a front face and a rear face; a cut-out arranged in said rear face of said elongated tooth member and having a top and bottom face being spaced apart from the top and bottom edges, respectively, of said elongated tooth member and a lateral engagement face provided with at least two elongated recesses therein arranged substantially normally to said lateral engagement face of said cut-out and extending parallel to the axis of said elongated tooth member substantially from the top to the bottom face of said cut-out; a supporting metal body including a backing portion fitting into said cut-out of said elongated tooth member and having a top and bottom edge and a frontal engagement face located between said edges and engaging said of said cut-out, said lateral engagement face top and bottom faces of said cut-out flaring slightly outward from said lateral engagement face toward said rear face of said elongated tooth member; at least two projecting lamellae on said frontal engagement face of said backing portion projecting substantially normally to said frontal engagement face, extending substantially from said top edge to sa1d bottom edge of said backing portion and being shaped for entering said elongated recesses in said lateral engagement face of said cut-out whereby said backing portion of said supporting body and said lamellae thereon can be brought to engagement with said cut out and elongated recesses, respectively, of said elongated tooth member only by a motion thereof being substantially normal to said engagement faces of said elongated tooth member and said backing portion; and binder means retaining said backing portion and said lamellae thereon in said cut-- having a front face outiand" elongated recesses; elongaterlutootmmcmbem 4.2m dehtahprosthesis;comprising, in combinae: tionsan elongated" toothmembenlof artificial resin r and a rear face'; acut-outi arranged in said :rear face cf said elongated tooth member and havin -a nand bottom face being spaced apart from the top and bottom edges, respeotivelyppf said elo'ngate'd tooth member and a lateral engagement facezproyided-with at least two elongated recesses therein-arranged substan-..-

tially' normally to said lateral LengagementifaCe of said cutout and extending parallel to the axis of said elongated tooth member substantially from the top to the bottom face of said cut-out; a supporting metal body including a backing portion fitting into said cut-out of said elongated tooth member and having a top and bottom edge and a frontal engagement face located between said edges and engaging said lateral engagement face of said cut-out; at least two projecting lamellae on said frontal engagement face of said backing portion projecting substantially normally to said frontal engagement face, extending substantially from said top edge to said bottom edge of said backing portion and being shaped for enterin said elongated recesses in said lateral engagement face of said cut-out whereby said backin portion of said supporting body and said lamellae thereon can be brought to engagement with said cut-out and elongated recesses, respectively, of said elongated tooth member only by a motion thereof being substantially normal to said engagement faces of said elongated tooth member and said backing portion; and a binder consisting of a material containing synthetic resin, said binder filling the portions of said recesses unoccupied by said lamellae and of said cut-out unoccupied by said backing portion whereby said supporting metal body and the lamellae thereon are firmly held in said cut-out and the recesses respectively in said elongated tooth member.

5. A dental prosthesis, comprising, in combina tion, an elongated tooth member of artificial resin having a front face and a rear face and having at least two elongated recesses in said rear face arranged substantially normally to said rear face and extending parallel to the axis of said elongated tooth member and spaced from the top and bottom edges of the same so as to be closed along their tops and bottoms, respectively; a supporting metal body including a backing portion having a top and bottom edge and a frontal engagement face located between said edges and engaging said rear face of said elongated tooth member; at least two projecting lamellae on said frontal engagement face of said backing portion projecting substantially normally to said frontal engagement face, extending substantially from said top edge to said bottom edge of said backing portion and being shaped for entering said elongated recesses in said rear face of said elongated tooth member whereby said lamellae on said backing portion of said supporting body can be brought to engagement with said elongated recesses in the rear face of said elongated tooth member only by a motion thereof being substantially normal to said rear face of said facing member, each of said lamellae being formed with at least one retention hole; and a binder consisting of a material containing a synthetic resin, said binder penetrating into said retention holes of said lamellae, filling the. portions of said recesses unoccupied by said lamellae and of said respectively, ofrsaidu References Cited in the file of this patent UNITED STATES PATENTS Name Date Low June 9, 1885 Number Number 675,881 1,481,209 2,308,195 2,314,503 2,394,659

8 Name Date Cassullo June 11, 1901 Kauffman Jan. 15, 1924 Morris Jan. 12,1943 Kurgas Mar. 23, 1943 Breyer Feb. 12, 1946 Saflir Apr. 16, 1946