US2186468A - Method of producing tooth forms - Google Patents

Description

Jan. 9, 1940.

I J. R. SCHWARTZ METHOD 0 F PRODUCING TOOTH FORMS V 1 I I I l r Filed May 5, 1938 I Fig. 7 1m 8 Q FIN ISHFD man u FORM ATTORN INVENTO B R. SC'HW TZ Patented Jan; 9, 1940 l UNITED Foams Jacob K. Schwartz, Brooklyn, Y. Application May 5, 1938, Serial No .;20c,1s9*

2 Claimsf 1o]. 1s -.-'55. 1)

My .present invention relates to methods of n and means for, producing; tooth forms, and more particularly to ainovel method of,1and apparatus.

for, producing crown forms.

5 It may. be stated that one ofthe main objects of my presentinvention is to provide a method of producing crown forms of: a wide variety of shapes and sizes; the method essentially com-v prising coating a tooth modelcomposed of a' substance easilyandquickly. soluble in a solvent,

which has no efiect on 'the coating material, a and subjecting the coated model tothe solvent action when the coating is dry. 1

Another important f'object of a my' invention is" 16 to provide a method of producing'dental crown" forms which includes the stepseof forming a, tooth crown model oi a, water-soluble composition'; coating. the model surface-wither waterinsoluble material; hardening-the coat; and fi-' 20 nally placedthe coated model in a waterloath;

therebyflto dissolve completely the model while leaving ari'gid shell whose form is exactly that:

of the model configuration. I 1 v Another object of the invention is to provide ing placed intoa bath, after drying and baking;

' to provide a clean separation oi therigid, formed coat from each model by a rapid dissolving of the model material. f}- l Other objects of my' inventionare toprovide dental model support-'jdviceS constructed posi- 40 tively to retain a largenumber of models during the coating of the lattem the' support devices be ing additionally providedwith speciall ydesigned' baking molds forjuse during the hardening stepl I 1 1 fisiprovidedwith, a. V-shaped circular-groove 4 which-registers with a-male elementz'on the sup- 9 port device to provide 'DOSitiYG IBtBIItiOIl Of the of the present-process.g.;

Still other objects of my invention" are to improve generally the'eiiiciency and speed of production of dental crown forms; andmore-espe cially to provide a method of producing cro-wnl forms which is reliable and economical.

The novel featureswhich I believe to be char acteristic of my invention'are setyforth inpar-i ticularity in the appended claimsptheinvention, itself, however, as to both itsorganizatiori and method of ,operation'will best beunderstood by".-

reference to "the following description taken in st0od"'tha;t in "out this invention a com, 5 ,51

model, -Fig. 8*:is a central, longitudinal sectional view 5.1. of a finished crown" form after removal of the connection with; the drawing in: which I have indicated v.jdiagnammatically several constructionsl'by the aid offwh'ich my. invention may be carried intoi'effect. Q i

In the drawing: 'Figs. land 2 showcentraL-ilongitudinal sec-, tion'al'flviews of alternate types of dental crown models adapted tqp in the-processhaq d to my invention, ,7 v

.Fig; 3 is a plan-view of a portion of amodeI "10 support device 1 adapted for use the type. sho-wninFig; 1

witli' models of 7 f1: isja transverse sectional view of the "support shown in Fig; 3,! and taken 'along,, line' I d.t-4 looking the: direction of the arrows, v "Fig; 5is a transversesectional vie'wo'f a mo di 1 --fied modelzsupportadapted foriuse' with models mg; 6 shoWsxthe support device o'f Fig. 4 fitted inltransverse section, H

' :7 is acentraltlongitudi lal sectional view of a coated model-just-priorto "removaloi the Referring nowto the accompanying drawing, I

'jwhereiri' like reference 'characters-in-th'e 'difiere en't :figures 1 denote similar constructional ele- 30 ments,-there are'shown in Figs. 1, and 2 different types of crown models which can housed-"to "produce crown forms 'thereof. .Thniodel in Fig. 1- comprises two essential sections; the sec tionsrare separated y afinished neck' line {whose function it is toidesignate the base ofgthe'crown formj after, the j coating operation ,isijcompleted.

The section 2 above line I is' thetruemodel, or

' core,= whose contouris to beduplicated in the" forms; :The section sbelow lineI l' is a locking 0 base whose"function'it is to cooperatejwith'a ,Y-model support device to retain the mooeim position during" the coating operation. The-base ;3

model.

'Themodelin Fig 2gmechanic'allyediffersfrom thatin 1 in that the locking base3 is proof any'des'ired shape. Thus, itis to be under- ,with a special bakingmold,. both being shown plete set of crown models may be molded to represent the crown contours of the upper and lower jaws, both anterior and posterior. 'Such complete sets of models may beof the type provided with a locking base of the type shown in Fig. 1, or they may have the type of locking base shown in Fig. 2.

Those skilled in the dental art are fully aware of the manner of molding tooth models such as shown in Figs. 1 and. 2. Each particular type of crown contour will have its set of"dies,,front and rear, to cast a model. When constructing a set of dies to mold the type of model shown gidity or configuration of the coating to be '30 quickly and completely soluble inwater.

in Fig. l, the dies will be constructed to provide the groove 6 in the base 3. Similarly in thecase of Fig. 2, each set of dies willbe constructed to produce a bore 4 in the base 3 of the model.

It will'be obvious that the molding dies can be 1 arranged in a'wide variety of contours and sizes; these will depend upon the requirements of the dental profession.

In molding the models it is desirable to "use for the com osition thereof a material generally soluble in a solvent which will not affect the ri.-

applied on the model. For example, when using a nitrocellulose solution for. coating the model, the latter is preferably composed of a substance Such a substance may be corn starch, potato starch or potato dextrine; or a mixture of plaster and any of the aforementioned substances may be used. Models composed of such materials are quickly soluble in hot water, while theinitrocellulose coat is completely unaffected by the-water- For the purposes of this method, however, the aforementionedmaterials are not the solematerials to be used. In general, as stated above, the material to be used for the model'will depend upon the acfor production of contour-forms, the models are I The latter ,may

'tion of the solvent bath upon the model'coating; the essential requirementbeing that the coating be unaffected while'the model core is bein'g dissolved. Of course, any desiredtype of model solvent other than water may be used.

When a group of models have been "selected mounted in; a support device. comprise, as shown in Figs. 3 and 4, a pair of metallic sections 5 and t which are mirror image duplicates "and; provide front and rear locking sections for the bases of models. -While Fig. 3

shows only a single locking wellv 8, it will be understood that as many similar units as desired" may be employed. Asshown in- Fig. 4, and assumingthe type of locking base shown inFig. .1

is employed, each locking wellcorresponds in contour to a locking base 3. Whena model base 3 is positioned between the sections 5-45, the base fits snugly in its well. Preferably, the neck line i will, be alignment with the top face 6 of. the 'support sections. A shallow basin 1 .is provided in the upper face, ii to collect the small excess ofcoatingsolution which may drip .frorn the model during the coating step, and

' lution of nitrocellulose.

locking well 9 of the type of support device adapted to position the models with looking bases shown in Fig. 2. In this case the support device is in one piece and a bore It is provided longitudinally through the successive wells 9. When the models are in position a rod (not shown) is run through the registered bores and bore Ill and locked in place. In this way the models of Fig. 2 may be locked in position for coating. Of course, any other type of lockingbase may be provided on a tooth model; also, support devices may be provided with any desired locking means adapted to cooperate with such locking bases.

' Assuming, now, that the models of a desired type of tooth contour are locked in position on a support device, the coating of the model sections 2 is begun. Let it be further assumed that the models being coated are those having locking bases of the type shown in Fig. 1, while the contour sections are those of Fig. 2. The actual coating with the nitrocellulosesolution is. preceded by providing. on the exposed surface of each model a glazed surface. This. is done to close the pores of the model-.material, and may be accomplished by. spraying the exposed surfaces with a fine layer of shellac or gelatine. This glazing coat should be of .amaterial which will not adhere. to the nitrocellulose coating,.and

is, furthermore, water-'solubleso that it will subsequently wash out with the modelmaterial.

, After the glazed surfaces are provided on the models, the latter are dipped-into an acetone 50- The consistency of the nitrocellulose solution (which may be of any type readily purchased on the open market) is such as to coat the exposed surface of each model With.a layer of uniform thickness. 'If desired,

the uniform coating canbe provided upon the models by spraying. In'actual usage the coating isextremely thin, and is of th'e order of onefourth of-a millimeterin thickness. The nitrocellulose coats/on-the models are permitted to dry and harden while still in thefsupport device. It will be appreciated that because of the common 'meunting for the plurality of models, it is possi ble to'eliminate the many. manipulations it would require to operate on each model separately. Once locked in, a support device, a great many models are simultaneously. operated upon for the successive steps of the process.

The coatings on the models having driedand hardened, there is, associated with ;the support 'device a special baking mold shown in Fig. 6.

In the latter there is shown only the relation be-.

tween'the specialjmold sections and the support I device sections. The specialmold may comprise complementary metallic sections i2 and When locked together, and as shown in Fig; 6, the sections l?.i3 provide a plurality of mold units;

in each mold unit I4 is disposed a coated model.

Hence, each mold unit it has a configuration exactly corresponding to':-,that er the models to be subjected toheat. The. dotted line 15 shows the space'occupiedby the uncoat'ed model; the space between line H5 and the mold unit surface'is that occupied by the nitrocellulose'co'ating. Any desiredtype of adjustable clamping means can be used to secure the special mold device to the support device. 5+6. 1 When the mold sections l2 iil have been'fittedin position and locked together, the assembly is placed in any desired type of baking oven. The nitrocellulose coats are subjected to dry: heat forfurther hardening.

The sections i2+:l3 .are then-removed, and the contoursections of. the modelsshearedofi at the neck lines 1. During the heat treatment the support device.

becomes highly frangible, and is thereby more readily dissolved.

Fig. 7 shows the sheared, coated model; the

coating [6 is rigid and transparent. It conforms exactly to the contour of the crown form. Since the neck line of each model is positioned in alignment with upper face of the support device, any well known type of slicing mechanism can be used to successively shear through the model bodies along the plane of the upper face of the For example, a power-driven, rotatable, circular knife, of proper dimensions, can be employed for this purpose. the periphery. of the base of the crown form is even, and will have no edge irregularities capable of harming the gum tissue since any excess coating material which may have accumulated on the portion of the model within the basin 1 will necessarily be cut oif from the remainder of the coating when the model is sheared by the knife.

The sheared, coated models are now passed into a bath of water. It is preferred to use water of a temperature suficiently high to dissolve the model body in a rapid manner.- The finished crown form is shown in Fig. 8; the model body has been removed without in any way affecting the configuration or rigidity of the coating I6. The aqueous solvent for the model material has no efiect on the nitrocellulose; however, it does dissolve the glazed surface on the model body. The separated crown forms may now be collected from the bath and dried.

While I have indicated and described a method of, and means for, carrying my invention into efiect, it will be apparent to one skilled in. the art that my invention is by no means limited to the particular apparatus shown and described nor to In this way the sequence of steps outlined; many modifications may be madewithout departing from the scope of my invention as set forth in the following claims. What I claim is: s V 1. In the art of producing dental crown forms, the method which includes molding from watertour section and a locking base, locking the base to a support and exposing only'the contour section, coating the surface of the exposed section with a layer of nitrocellulose which becomes rigid upon drying drying the layer of nitrocellulose, shearing the coated contour section from said base at the support whereby the base of the nitrocellulose layer is formed even and without irregularities, and dissolving the contour section away with water to effect a separation of the rigid nitrocellulose coat.

layers on each surface to become rigid thereby to I provide said forms, shearing the coated contour sections away from the base sections at said support whereby the base of each layer of nitrocellulose is formed even and without irregularities, and

soluble material a tooth model which has a con- 7 subjecting the sheared contour sections to hot JACOB R. SCHWARTZ.

Images