US 4,468,484 AGrant
Settable Alignate Compositions Containing Polyacrylamide
Issue Date:1984-08-28
•8 Claims
Abstract
An oral, settable, dental composition is prepared by interacting Component A containing an alkali metal alginate in an aqueous paste with Component B containing a divalent metal salt such as calcium sulfate and a reaction rate retarder such as tetrasodium pyrophosphate in a fluid plasticizer paste that is substantially free of unbound water. A non-grainy, smooth texture of the pre-set, blended components is obtained by incorporating into Component A a polymer comprising polyacrylamide.
Metadata
Assignee
- Laclede Professional Products, Inc.
Inventor
- Michael A. Pellico
Application Information
Application Number:US 4902947
Filing Date:1983-05-02
Priority Date:1980-12-29
Art Unit:143
Classifications
IPC:
A61K 608
Field of Search:
5235241064331092838.5 D;35;206;208;209213;214
Patent Drawings
This patent does not have any drawings.
Description
Examples
The following examples further illustrate the invention.
In Example I through Example IV, Components A and B were prepared by blending the dry ingredients with the fluid ingredients in a high-speed, stainless steel blender to form light pastes. The formulations were so designed that 4 volumes of Component A and 1 volume of Component B provided suitable weight ratios for interacting the alkali metal alginate with the divalent metal salt. Components A and B were evaluated for pre-mix shelf life and ease of mixing, and resulting mixtures of Components A and B were evaluated for set time and moisture loss at 72.degree. F. Components A and B were hand-mixed in a plastic mixing bowl. Set time was measured as the length of time to convert the fluid composition to a tack-free gel. Moisture loss was determined by weight difference over a specified period of time.
Example I
Example Ii
Example Iii
Example Iv
Example V
This example illustrates a formulation for Component A which has a very heavy, putty-like consistency.
Example Vi
This example illustrates various ingredients and proportions thereof which can be used in formulating Component B.
Example Vii
The following composition was prepared as a blend in the manner of the prior art.
Promptly following preparation of the composition, a first portion thereof was mixed with a suitable amount of water and evaluated for set time which was 3 minutes. A second portion of the composition was stored for 6 months at 55% humidity and then evaluated for pre-mix shelf life, ease of mixing and set time. The stored composition had aggregated in the container, and when mixed with water was grainy and difficult to mix. The set time for the stored composition was 1.5 minutes. It is theorized that this shelf life deterioration is due to moisture absorption which allows the calcium sulfate to interact with a significant quantity of the tetrapotassium phyrophosphate.
Example Viii
This example shows that if the alkali metal alginate component (Component A) is formulated with a metal oxide and a double metal salt, shelf life stability begins to deteriorate within a relatively short time period.
4 volumes of Component A were mixed with 1 volume of Component B having the formulation set forth in Example I and the system was evaluated for ease of mixing, set time and compressive strength as follows:
Example Ix
This example illustrates a two-component alginate formulation which, when blended, provides a relatively low viscosity, settable composition that is adapted to be applied with a syringe to a dental surface or other body part such as an ear for making an impression for use in constructing an appropriate form.
U.S. Pat. No. 2,756,874 (Erickson et al., 1956) discloses a self-contained, two-component alginate impression system, wherein one component contains potassium alginate and tetrasodium pyrophosphate in an aqueous paste and the other component contains calcium sulfate in an aqueous paste. The patentees point out and emphasize that the reactant (calcium sulfate) and retarder (tetrasodium pyrophosphate) cannot be incorporated in the same aqueous composition. The invention described herein is distinguishable from the disclosure of U.S. Pat. No. 2,756,874 in that the divalent metal salt component contains both reactant (calcium sulfate) and retarder (tetrasodium pyrophosphate) in a non-aqueous fluid plasticizer paste.
Polyacrylamides
Components A and B, when blended, have a tendency to appear grainy and form lumps. In accordance with this invention, it has been found that a non-grainy, smooth texture of the pre-set, blended ingredients can be obtained by incorating into Component A a polymer comprising polyacrylamide. The polyacrylamide is advantageously incorporated into Component A in an amount from about 0.5 to about 6.0 wt. % based on the weight of Component A.
The polyacrylamides which can be used in this invention include those which are available from American Cyanamid Company under the trademark CYANAMER as, for example, CYANAMER P-250 identified as a homopolymer of acrylamide having a molecular weight of approximately five million to six million, CYANAMER A-370 identified as modified polyacrylamide having a molecular weight of approximately 200,000 and a substantial carboxylate content, and CYANAMER P-26 identified as modified polyacrylamide having a molecular weight of approximately 200,000 and a low carboxyl content.
Example X
The following examples show varying concentration levels and molecular weights for the polyacrylamides which can be used in this invention. The CYANAMER trademark used in the example identifies those polyacrylamides which have been hereinabove described.
In view of the foregoing description and examples, it will become apparent to those of ordinary skill in the art that equivalent modifications thereof may be made without departing from the spirit and scope of this invention.
Claims
That which is claimed is:
1. In a two-component system interactable to form an oral, settable, dental composition comprising: (i) Component A containing an alkali metal alginate selected from the group consisting of sodium alginate, potassium alginate and mixtures thereof in an aqueous paste; and (ii) Component b containing a slightly water soluble, divalent metal salt and a reaction rate retarder in a fluid pasticizer paste that is substantially free of unbound water, said Component B being so formulated that a pre-selected quantity thereof contains from about 0.5 to about 1.2 parts by weight of divalent metal salt per 1.0 part by weight of alkali metal alginate in Component A, said reaction rate retarder being present in an amount from about 0.02 to about 0.13 part by weight per 1.0 part by weight of said divalent metal salt, and said fluid pasticizer being present in an amount from about 0.75 to about 2 parts by weight per 1.0 part by weight of said divalent metal salt, wherein: said divalent metal salt is a member selected from the group consisting of calcium sulfate, ferrous sulfate, zinc sulfate, divalent metal salt of fatty acid and mixtures thereof, said reaction rate retarder is a member selected from the group consisting of phosphate, pyrophosphate, citrate and silicate salts of sodium, potassium and mixtures thereof, and said fluid pasticizer is a member selected from the group consisting of glycerol, propylene glycol, polyether glycol, oleyl alcohol, light silicone oil, light mineral oil, vegetable oil and mixtures thereof; the improvement which comprises incorporating polyacrylamide into Component A in an amount from about 0.5 to about 6.0 wt. % based on the weight of Component A to thereby obtain a non-grainy, smoooth texture of the pre-set, blended components.
2. The two-component system of claim 1 wherein the polyacrylamide is a homopolymer of acrylamide and has a molecular weight from about five million to about six million.
3. The two-component system of claim 1 wherein the polyacrylamide is a modified polymer of acrylamide and has a molecular weight of approximately 200,000 and a substantial carboxylate content.
4. The two-component system of claim 1 wherein the polyacrylamide has a molecular weight of approximately 200,000 and a low carboxyl content.
5. In a method for preparing an oral, settable, dental composition which comprises interacting: (i) Component A containing an alkali metal alginate selected from the group consisting of sodium alginate, potassium alginate and mixtures thereof in an aqueous paste; and (ii) Component B containing a slightly water soluble, divalent metal salt and a reaction rate retarder in a fluid plasticizer paste that is substantially free of unbound water, said Component B being so formulated that a pre-selected quantity thereof contains from about 0.5 to about 1.2 parts by weight of divalent metal salt per 1.0 part by weight of alkali metal alginate in Component A, said reaction rate retarder being present in an amount of about 0.02 to about 0.13 part by weight per 1.0 part by weight of said divalent metal salt, and said fluid plasticizer being present in an amount from about 0.75 to about 2 parts by weight per 1.0 part by weight of said divalent metal salt, wherein: said divalent metal salt is a member selected from the group consisting of calcium sulfate, ferrous sulfate, zinc sulfate, divalent metal salt of fatty acid and mixtures thereof, said reaction rate retarder is a member selected from the group consisting of phosphate, pyrophosphate, citrate and silicate salts of sodium, potassium and mixtures thereof, and said fluid plasticizer is a member selected from the group consting of glycerol, propylene glycol, polyether glycol, oleyl alcohol, light silicone oil, light mineral oil, vegetable oil and mixtures thereof; the improvement which comprises incorporating polyacrylamide into Component A in an amount from about 0.5 to about 6.0 wt. % based on the weight of Component A to thereby obtain a non-grainy, smooth texture of the pre-set, blended components.
6. The method of claim 5 wherein the polyacrylamide is a homopolymer of acrylamide and has a molecular weight from about five million to about six million.
7. The method of claim 5 wherein the polyacrylamide is a modified polymer of acrylamide and has a molecular weight of approximately 200,000 and a substantial carboxylate content.
8. The method of claim 5 wherein the polyacrylamide has a molecular weight of approximately 200,000 and a low carboxyl content.