Package of reversible thermoplastic impression composition

Nov. 7, 1939. L. e. HARRISON 2,178,663

PACKAGE OF REVERSIBLE THERMOPLASTIC IMPRESSION COMPOSITION ' Filed July 24, 1936

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Patented Nov. 7, 1939

2,178,663

UNITED STATES PATENT OFFICE

2,178,663

PACKAGE OF REVERSIBLE THERMOPLASTIC IMPRESSION COMPOSITION

Laurence E. Harrison, Altadena, Calif., assignor, by mesne assignments, to Surgident, Ltd., Los Angeles, Calif., a corporation of California

Application July 24, 1936, Serial No. 92,463

Claims. (Cl. 206—46)

This application is a continuation-in-part of my^; application Serial No. 1,744, filed January 14, 1935, and relates to an advantageous package in which a reversible thermoplastic dental impresS sion composition may be packaged and marketed.

The principal object of the invention is to provide a package which may be easily and cheaply prepared and which will preserve the material in an uncontaminated state until used.

Numerous dental impression compositions have been disclosed, which have one characteristic in common, namely, that they are relatively rigid . when at ordinary atmospheric temperatures and are fluent or plastic at an elevated temperature.

I® These impression compositions are employed by the dental practitioner by rendering the same fluent by heating, cooling the fluent material under conditions of agitation or other physical manipulations until a temperature low enough for 20 insertion into the mouth of a patient is obtained, after which the material is placed in a suitable tray or the like and an impression obtained of the desired portion of the patient’s mouth, the impression being cooled in place to a relatively rigid 25 state and subsequently, withdrawn from the mouth and employed in the production of plaster casts or other reproductions. Certain of these compositions comprise a base material of a hydrocolloid nature such as. agar-agar or glue, toan gether with certain modifying agents contributing to the properties of the material both in the fluent and the relatively rigid state, pne type of material is described in the U. S. patent to Poller No. 1,672,776, and other compositions are 35 describedin my issued Patents Nos. 1,897,034, 1,920,857, 2,006,549, 2,020,311, 2,021,058, and 2,021,059.

The non-hydrocolloid materials may be marketed without any particularly elaborate type of ₄0 package, but are preferably preserved against contamination by contact with human hands or other detrimental agencies, so that the material may be introduced into the patient’s mouth in a sterile condition. In such compositions as are of 45 a hydrocolloid nature or contain any significant proportions of hydrocolloid material, it is necessary that the package provide adequate hermetic conditions whereby no significant moisture loss is experienced by the material during storage condi;0 tions. Such hydrocolloid materials have been conventionally enclosed in a tin-foil wrapper or the like, without sealing, and since such a package is of itself not properly resistant to moisture loss, a plurality of such packages are placed in a her55 metically sealed rigid container, such as a friction lid can or the like, and the desired quantity of material removed from such container for use. Materials so packaged are intended to be converted into the desired fluent state for use by insertion in a mechanical device which may be heated exteriorly to raise the material to the desired temperature and in which a kneading or mixing of the material may be obtained to thoroughly homogenize the same.

According to the present invention a substan- 5 tially continuous envelope of flexible material is provided for a body of the impression material, which adequately protects the material from the air as well as from contact by human hands or other agencies, and serves as a suitable container 1® for the impression material during heating and kneading. preparatory for use, and in its preferred embodiment also protects the material against moisture loss during storage.

The accompanying drawing illustrates two em- 15 bodiments of the invention,· and referring thereto:

Fig. 1 is a partly broken-away side view of one embodiment of the invention, which may be formed by a dipping procedure; and 20

Fig. 2 is a partly broken-away view of an alternative embodiment, which may be formed from preformed tubular envelope material.

As a specific example of a reversible hydrocolloid impression material to which the present 25 invention is adapted, I may take from 140 to 200 grams of an oleaginous material such as resin oil to which is added approximately one-half per cent of a suitable emulsifying agent such as triethanolamine, heat the mixture to about 100° C. ₃₀and emulsify the same with approximately 90 grams of water. To the above emulsified mixture I may add from 100 to 200 grams of a balatalike thermoplastic substance such as guttapercha, balata, or a balata-like rubber isomer ₃₅such as described in Industrial and Engineering Chemistry, vol. 19, pages 1325 and 1333, December, 1927, preferably in the form of a 25% solution in benzol or other suitable solvent. This thermoplastic material emulsifies in the above 45 mixture and is homogeneously distributed therethrough under agitation, the material being kept hot to drive off the solvent. Following the emulsification of the above materials I may add approximately 2000 grams of an aqueous solution of 45 a reversible hydrocolloid such as agar-agar, for • example, 150 grams of agar-agar dissolved in 1900 grams of water. The hydrocolloid material is preferably added hot, and upon agitation will emulsify in the above mixture to form a homo- 50 geneous mass. To the above mixture approximately 300 grams of wax may be added, for example, a mixture of waxes containing four parts ceresin and one part candelilla, in melted condition, which , wax also emulsifies in the mixture. .55 Suitable amounts of desirable flavoring, scenting, and/o-' coloring material may be added to the finished mixture and the same may be cooled to a semi-plastic state and extruded through a die to form bodies of the material of cylindrical or other

2,178,663 desired shape and of the proper size, which upon cooling to their relatively rigid or solid state are ready for packaging.

A body of reversible hydrocolloid impression ₅ material, formed into cylindrical or any other suitable shape by molding or otherwise, may according to this invention be dipped in a solution of a suitable cellulose compound adapted to form, upon evaporation of the solvent, a continu₁₀ ous coating of suitable thickness over the surface of the molded body. For this purpose, I may use, for example, a solution of Celluloid or cellulose acetate composition in ethyl acetate, of suitable concentration, and the dipping may 15 be carried out by inserting a wire into the molded body I, as shown in Fig. 1, at some such location as is indicated by the dash line A, dipping the same by means of said wire into said solution; removing the same therefrom, allowing the 20 coating to partially dry and thus forming a tubular container or envelope 2, removing the wire, and then applying a small quantity of the same or equivalent solution to the opening through which the wire was drawn as at 3,' and 25 allowing the entire coating to thoroughly dry.

The dipping procedure may be repeated several times, if necessary, to provide a coating of adequate thickness.

A preferred form of package may be prepared 30 by inserting a suitably formed stick 4 of the impression composition into a tubular container 5 of rubber or comparable material, suitably sealing the ends of the envelope, which may be al' lowed to project beyond the ends of the stick a 35 short distance, by means of a wrap of wire 6 or the like to bring the envelope ends into close compressive engagement so that an effective fluid-tight seal is produced by the envelope material itself. If the ends of the rubber envelope 40 are securely brought into engagement and held in such condition by an adequate wrap of such wire or the like, the package will be effective to prevent any loss of moisture from the contained material.

Either of the above-described forms of package may be prepared for use in the following manner: The sealed package is dropped into a body of water which is brought to a boil, and maintained at that temperature for a suitable 50 period such as from five to ten minutes or more, dependent upon the size of the body, and is then removed and is preferably kneaded between the hands until it has cooled to a temperature adjacent body temperature or at least to a tempera55 ture such that the material may be comfortably inserted within the patient’s mouth. The use of an envelope or package of-flexible material permits adequate kneading of the heated impression material within said envelope, to homog00 enize the impression material and prepare the same for use. The envelope may then be opened by slitting the same at one end or cutting one end of the envelope off with a pair of shears or the like, and the composition may then be ex55 traded, by squeezing the envelope, into the customary type of dental impression tray employed by dental practitioners. This tray is then inserted into the patient’s mouth and the desired impression secured.

γ₀ It will be· apparent that the first described form of package is not entirely adequate of itself to prevent escape of moisture under storage conditions, and it may be necessary to enclose a plurality of such packages in a suitable hermetically sealed can or the like after the manner of the tin-foil wrapped packages above described. This type of package is, however, clearly adapted to the above described method of homogenizing the material in fluent condition for use and extruding the material from the envelope. The rubber envelope type of package immediately above described is adequate to prevent moisture change in the contained material under any con- 10 ditions, and even though a body of material has been placed in the desired fluent condition ready for use by the dental practitioner, if it should develop that the patient does not keep his appointment and the material is not to be used, 15 the package may be returned to storage without change in the physical properties of the contained material. ·

It Will be appreciated that the above specific example of a reversible hydrocolloid dental im- 20 pression material is not the only composition with which the present described package or method of use is applicable, as any of the reversible thermoplastic materials described in the several above-mentioned patents are clearly use- 25 ful therein. Other flexible coating materials than rubber or Celluloid will also occur to one skilled in’the art as being useful in the formation of the package, using either a preformed container or a container formed by a dipping procedure, or any other suitable means for packaging the impression material in the container. It will also be apparent that the rubber package is not necessarily sealed by a wire wrap as specifically above described, inasmuch as cementlike agencies may be employed for that purpose.

I therefore do not consider myself limited to , the specific elements and conceptions herein set forth but rather to the scope of the appended claims/ The term “flexible” as used herein will 40 be understood to designate a material which is sufficiently capable of plastic or resilient deformation at temperatures within the kneading range to. permit the kneading operation to be carried out. Furthermore, it will be appreciated , that the envelope material is preferably nonmetallic in nature, inasmuch as a flexible envelope of pietal would necessarily be relatively thin-walled, and would thus be subject to rapture in the kneading operation.