US2520265A - Method and means for making artificial dentures - Google Patents

Description

E. E. WARREN Aug. 29, 1950 METHOD AND MEANS FOR MAKING ARTIFICIAL DENTURES Filed Oct. 10, 1947 INVENTOR WARP/37V EDGAR 5 tures.

without provisionof interprox-imal spaces, natur-al interproXimaI-spacesare closed at the occlusal plane bythecontact points of'theteeth, -such spaces, if formed inthe temporary'wax base plate in which the artificial r teeth are arranged and embedded toiorm the set up, would ordii narily constitute undercuts fromwhich it would Patented Aug. 29, 1950 UNITED :STATES PATENT OFFICE -='METHOD AND MEANS; FORTMAIQNG ARTIFICIAL-DENTURES S -Claims. 1

Denture's'a's herein used means'artificial den- Teeth meansartificialteeth. Dentures of 'the t'ypewherein 'the' teethare molded in a body or base of hard'ru'bber or synthetic resin are, so far as I know, always molded Since be extremely difiicult toremove the investment "material without danger of damaging ordislocating or marring parts-ofthe denture becausethe investment material adheres tenaciously to the teeth. There are other reasons orexcuses for -not--forming (e. --g.--carvi-ng) interproximal spaces in the dentures.

plate material -inthe interproximal spaces is For example; the base urged as lendinglateral-strength or-dislocationresistance to the individual-teeth and facilitating. cleaning: of the" dentures by-the user -Actually it is --practically-impossible by the useof carving tools includingthesrnallest dental burrs available to -form--clean-andcompletednterproxi- -mal spacesy-andif it-were possible it Wouldbe prohibitively costly. Gonsequently the patient -or-user is made acutely conscious bytongue-feel ofthe-fact-that the-teeth'are unnatural, and

tends to displacethedenturesby attempting to I force saliva and air-through the imperf'orate wall formed around the plateby the-teeth andintervening plate-material, either by pressure or suction. I Moreoven-the'lack of -interproximal spaces -afiects thespeeclr and: makes the dentures appear --to 'be-artificial- -on casual-observation atclose range,=-whereas theoppositeis desired by theuser.

' I -have discovered -a*-method and-apparatus wherebysmooth and natural interproximal spaces -maybe: provided "onartificial-dentures without departingdisadvantageously from accepted prac- 'tice-or technic used:in-:their formation; without disproportionate cost; and without actual sacrifice of:strength pr' utflity, thus indicating the principal objects of the present invention. Otherwise stated the primary object is to provide a new and efficient method and apparatus for forming interproxim'al spaces on artificial dentures so that all the defining surfacesof the interproximal spaces 'w-il1 be"'natural in form, smooth, clean and polished and will not tend mto collector retain food or stain.

"Briefly; I provide interproximal spaces on the usual wax set-up and fill or approximately fill '2 those' -spaces with strips of readily flexible and elastic barrier material, the physical character- 'isticsof'which are" such that the barrier material willn'ot fuse/weld or adhere strongly to r 5 the base plate'material used to form the'finished '-"denture 'or to the teeth embedded thereby in the --moldingpiooessybut which "can easily besepa rated' cleanly from the molded denture along with the surroundinginvestment "material, *leaving the' smooth clean" and polished surfaces referred tor-aboveand without'r'equiring any subsequent :oper'ationstobe-performed by hand. Typical iorms-"of the-apparatus and the preferred'procedur in practicing the method hereof are illustrated-in the accompanying drawing wherein:

Fig; 1- is a 'perspective viewpf a maxillarywax set-uppn'the usual c'ast model of the oral cavity regibn tobe fitted; the View showing two of the -'elastic barrier strips" hereof in'place'between re- :spectlvamutuaHy adjacent artificial teeth;

"Fig;-2*isa palatal 'viewof the Wax set up and two' barrief strip'sin' place;

-Figsi s and 4am sectional views taken respectively learigthwise'and crosswise of a row'of posterior teeth on the set-up;

""Figs. S'and 7 are-"sideelevations'of preferred forms 'of 'strips designed for use "respectively to torm or d'etermine interproximal spaces for ante- 'rior andposterior'teeth;

FigsZ G and' 8are' transverse sectional views as indicated "oriFi'gs. 5 and 7 respectively; and

Fig. Q 'isa'paIa'tal vi'ew of one half of a typical mbldingflask sl'iowinga; set of maxillary teeth and a fuH CompIInent"of theelastic strips emb'dcfied in investment material contained in the "flask ready for placement of raw' 'pla'stic in the cavity ofth'iho'ld. I

Themethod'hereof will be described in confiection withbnly the p'e'rtinent steps in making a typ1-"-l"dfiture from' modern plastic or synthe'tic resin which} under processing heat and -pressurefwill notweld 'to rubber, thus excluding a rubber. Acryl'ate is an example of synthetio re'sinplast'it'f ri'ow in common use.

' ---to' 4; 'theanterior teeth are'designa ted' nd the p'osterior t'e'e'th P, 'The molded w'ax' body l teriip'o'rarily embedding the root portions of -the teeth as usualo l erlies and is worked to proper 'form on the-usualartificialstone model -'or 'case 2' which, a'fter' 'appropriate treatment (e5 gfdoil overlay,"etc;not'shown) fdrms: part "of' the 'ino'ldfcavity" for the plastic base plate. Afterthe teethhave beenfound to be properly 'ari*an'ge d"-or see in the wax, thewax is'cutor molded to form the desired or appropriate contours. In accordance with the present method, interproximal spaces 3, Fig. 3, are formed on the set-up as with a narrow spatula, either by cutting away or molding of the wax during or afte formation of other gingival margin areas on the wax.

The barrier strips are elastic rubber which may be natural or synthetic. The barrier strips are preferably of two types, indicated 5 and 6, designed respectively for forming the anterior and posterior spaces. The strips, as shown particularly by Figs 4 to 8, are elongated pieces of elastic rubber of cuneiform o wedge-shaped cross section and tapering gradually as at l nearly to a. point to form one extremity. Both ends could be thus pointed. The gradual taper assists in initially inserting the ends of the strips into the interproximal spaces on the wax set-up, some of which spaces are extremely narrow. An additional refinement is to embed protruding filaments 8 of flexible material (e. g. synthetic fibers or silk) into the points 1 to assist in inserting them. The flexibility of the points or inserts is desirable if not necessary because the spaces are frequently curved on short radii in general con-v formance with the interproximal gingival margin.

The strips 5 for the anterior interproximal spaces may be made with a more elongated cross sectional height and less divergence between the sides than the strips 6 for the posterior spaces. Additionally, further in view of the variation in size of the interproximal spaces, the strips are preferably of gradiently increasing dimensions from one end to the other (see Fig. 2), being variably positioned to select the portion of each strip which best fits each space. Arcuate indentations (one or more) may be formed as at ID or [a on the strips generally to fit the anterior gingival margins defining the base portions of the interproximal spaces, and one or more arcuate but wider indentations is or are formed as at H or I la on the strips 6 with the view to fitting as nearly as possible the differin interproximal marginal areas at the respective regions mentioned.

The principal advantages of using elastic strips as barrier material are that, once inserted, the pointed end and the wider shank may be grasped as between the thumbs and index fingers of respective hands or by forceps or tweezers and the strips then stretched to reduce their cross sectional dimensions, thus enabling easy selective placement in the most ideal position without dragging the strips against the teeth and thereby tending to dislocate them from set position in the relatively soft and fragile wax. When the tension is released, assuming proper selective placement, the relaxed strip expands in cross section and very neatly fills the interproximal space.

After the complement of strips -5 and 6 has been placed, it is recommended that the free ends of the strips be severed and removed (e. g. by scissors) as along the lines C and C, Figs. 2 and 4, better to place the investment, to enable inspection of the molded wax; remodeling thereof where necessary and, later in order to facilitate removal of the investment material from around the teeth and molded base plate.

Fig. 9 as indicated above shows the root portions of the teeth protruding from the hardened investment material forming the lingual side of the mold cavity after the wax has been removed. It will be noted that the ends of the strips 5 and 6 are embedded in said material, but that the portions of the strips which lie in the interproximal spaces are exposed. From this point on the usual technique is followed in completing the denture. The raw plastic material is packed and pressed over the artificial teeth and investment When the male part of the flask containing the model is closed under pressure against the invested case. The case is then conventionally cured as in a curing tank. For further discussion of the technique generally in relation to acrylic resin denture materials reference is made to The American Textbook of Prosthetic Dentistry (L. Pierce Anthony D.D.S., editor), 7th edition, pages 470 thru 472. When, after curing of the case, the investment surrounding the normally exposed parts of the teeth is fractured and removed during deflasking, the strips are withdrawn with the fragments; the strips being pulled apart when necessary due to having been bonded in opposing fragments of the investment material. The barrier material leaves all the interproximal-space-defining surfaces smooth, clean and polished, requiring no further operation as with burrs or other tools.

I claim:

1. In the described and indicated process of making artificial dentures by molding plastic base material around the teeth, the method of providing interproximal spaces on such dentures comprising forming the spaces in the wax setup and inserting elastic strips in the spaces, which strips are of a material which will not weld to the plastic base material used.

2. The method according to claim 1 wherein the plastic is a synthetic resin on the order of acrylate, and the strips are rubber.

3. As a barrier for use in forming interproximal spaces on dentures in dental laboratory technique as described, an elongated elastic strip of wedged shaped cross section provided with a sufiiciently narrow flexible approximately pointed end portion for enabling relatively easy insertion into said spaces on a wax setup, the strip for the greater part of its length being stretchable lengthwise so as temporarily to reduce its cross section for easy placement between the teeth on the setup and whereby the strips will more nearly fill said spaces when relaxed after stretching.

4. A barrier strip according to claim 3, having a leader filament embedded in and projecting lengthwise from its narrow end.

5. A barrier strip according to claim 3, having a curved indentation along the base portion of its wedge shape adapted approximately to fit a gingival margin defining an interproximal space.

6. As a means for forming interproximal spaces in dentures and for use in connection with settin up of the teeth in and on a readily sculptured base to be supplanted by permanent denture base material, a barrier strip of flexible elastic hence stretchable material said strip being of elongated form, wedge-shaped in cross-section and tapered longitudinally toward one end for easy insertion between the teeth on such base. EDGAR E. WARREN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,527,028 Daniel Feb. 17, 1925

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