JP2014156437A - Dental alginate impression material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dental alginate impression material which has a long hardening time (i.e., a sufficient operation allowance), and expresses good distortion properties (i.e., high strength of a cured impression material).SOLUTION: Disclosed is a dental alginate impression material characterized by containing (A) calcium sulfate, (B) metal salts whose solubility to water of 20°C is 0.1-1.5 g/L and whose ionization tendency is smaller than that of calcium, such as magnesium phosphate or magnesium pyrophosphate, and (C) monovalent alginate salts.

Description

  The present invention relates to a dental alginate impression material, and more particularly, to a dental impression material in which an alginate and calcium sulfate are reacted to form a gel.

  When a cast crown restoration process or a defect prosthesis process is required to restore a tooth or the like, first, a mold such as an abutment tooth is taken. Next, a model made of gypsum or the like is produced using the obtained mold. And a prosthesis is produced based on the model, and the produced prosthesis is attached to an abutment tooth or the like. The mold such as the abutment tooth is referred to as an impression, and a curable material for obtaining the impression is referred to as an impression material. As this impression material, an alginate impression material, an agar impression material, a silicone rubber impression material, a polysulfide rubber impression material, a polyether rubber impression material, or the like is used. Among them, the alginate impression material is most widely used because it is inexpensive and easy to handle.

  The following procedure is used to obtain an impression using an alginate impression material. First, an impression tray simulating a dentition is provided with kneaded components constituting the alginate impression material. Next, a tray with impression material is pressed against the teeth so as to wrap the teeth in the oral cavity. Then, after the alginate impression material is cured, the alginate impression material and the tray are integrally removed from the teeth and removed from the oral cavity.

  In use, the alginate impression material is used by kneading an alginate monovalent salt such as sodium alginate, a gelling reagent such as calcium sulfate, and a main component such as water. When these components are kneaded, calcium ions released from calcium sulfate, which is a gelling reaction agent, react with alginate and cure (gelation) proceeds.

  In the state before use, the alginate impression material is a powder type in which the solid content excluding water is powdered, or a paste mainly composed of alginate and water (base paste) in order to ensure storage stability. ) And a paste (curing agent paste) mainly composed of a gelling reagent. In use, in the powder type, powder and water are kneaded, and in the paste type, two types of paste are kneaded.

  Here, in the case of a powder type alginate impression material, a skill of manual operation is further required for the kneading operation. If the surgeon is immature, not only will air bubbles that cause a drop in impression accuracy be included in the impression material paste, but it will be easy to miss the timing of taking the impression described above, and it will be difficult to obtain an accurate impression. It is. In contrast, paste-type alginate impression materials can be easily automated and labor-saving by using a dedicated kneading device for kneading the base paste and curing agent paste. It is easy to obtain a highly accurate impression without any difference. For this reason, in recent years, paste-type alginate impression materials are becoming popular in the form of replacing powder-type alginate impression materials.

  The most important physical property required for impression materials is impression accuracy. In order to obtain an impression with high impression accuracy in clinical practice, it is important to press the kneaded impression material on the teeth in a timely manner. If this timing is missed for some reason during the procedure and the impression material is hardened to some extent, it will be hardened with distortion inside the impression material, making it difficult to obtain a highly accurate impression. Become. Therefore, it is necessary to increase the initial gelation speed of the impression material, that is, to make the operation margin time as long as possible so as not to fail to obtain the impression. In general, as an impression material having a good operation allowance time from this point of view, it is preferable that the viscosity is kept at a low level of 1000 dPaS (decipascal second) for at least about 2 minutes from the start of kneading.

  Another requirement for obtaining an impression with high impression accuracy is the distortion physical properties (elastic strain, permanent strain) and cured body strength of the impression cured body. The impression material precisely transfers the tooth by being in close contact with the tooth. Therefore, when removed from the tooth, the impression material must be removed with a considerable force, and the impression hardened body is deformed not a little. Here, when the elastic strain and permanent strain of the impression material are large, the impression material is deformed at the time of removal despite being pressed at the best timing, and as a result, a highly accurate impression cannot be obtained. Furthermore, in a case having a large undercut, since a greater force is applied to the cured body, the cured body must have a strength sufficient to withstand this. However, the conventional alginate impression material is not satisfactory one step from the viewpoint of such a cured body strength. This is because, in the cured alginate impression material, after the operation allowance time has elapsed, in a state where the viscosity of the kneaded product has increased, its curability is drastically decreased and the curing reaction does not proceed sufficiently. Conceivable.

  Here, as a technique for adjusting the initial gelation time of the alginate impression material, by blending a curing retarder composed of an alkali metal salt of phosphoric acid such as sodium pyrophosphate or trisodium phosphate, It has already been reported that the gelation reaction rate can be greatly delayed (Patent Documents 1, 2, and 3).

  In addition, as a technique for increasing the strain physical properties of the cured body and the strength of the cured body, the strain physical properties and the cured body can be obtained by blending a filler such as diatomaceous earth, a curing aid such as magnesium oxide, zinc oxide, and potassium fluoride titanium. It has been known for a long time that the strength can be improved, and is well known to those skilled in the art (Patent Documents 1, 2, 3, and 4).

Japanese Patent No. 2793744 Japanese Patent No. 4210360 Japanese Patent No. 4159839 JP 2002-161014 A

  Conventionally known curing retarders composed of alkali metal salts of phosphoric acid such as sodium pyrophosphate and trisodium phosphate have a high solubility in water, so that a large amount of phosphorus is immediately added when kneading each component of the impression material. Acid ions are liberated, and calcium ions liberated from calcium sulfate are captured and insolubilized. Therefore, an alginate impression material containing such a curing retarder can slow down the gelation reaction rate at the beginning of kneading, and is effective in securing an operation surplus time. However, the blending effect of the alkali metal phosphate is used up at the beginning of kneading of the alginate impression material. Moreover, since sodium ion is a monovalent metal ion, even if the free sodium ion forms a salt with alginic acid, it has no action to improve the mechanical strength of the cured product.

  On the other hand, magnesium oxide, zinc oxide, potassium titanium fluoride, etc., formulated to improve the strength of the cured product, although the mechanical strength of the cured product is improved, conversely, the curing activity becomes too high and the operation margin time is increased. It will be lost. In addition, it is possible to improve the strength of the cured body by blending a filler such as diatomaceous earth, but in an impression material having a sufficiently long curing time, the blending amount must be increased in order to increase the strength. In such a case, the curability of the alginate was adversely affected, and conversely, the permanent set was lowered.

  From the above, it has been a major challenge to develop an alginate impression material that can increase the reactivity at the end of the curing period, obtain a cured product with high mechanical strength, and can sufficiently secure an operation surplus time.

  The present inventors have intensively studied to overcome the above problems. As a result, it has been found that the above problem can be solved by blending a dental salt alginate impression material containing calcium sulfate and an alginate with a metal salt having a solubility in water within a specific range.

That is, the present invention provides (A) calcium sulfate,
(B) a metal salt having a solubility in water at 20 ° C. of 0.1 to 1.5 g / L, an ionization tendency smaller than calcium, and (C) alginate monovalent salt,
It is a dental alginate impression material characterized by including.

  The alginate impression material of the present invention has a highly advanced curing reaction and has good distortion physical properties, that is, high strength of the cured impression material. Therefore, an impression with high accuracy can be obtained in the oral cavity. Furthermore, because of its low solubility in water, it has little effect on the active curing reaction at the beginning of kneading, and even when a curing retarder is blended, the good curing delay time secured by this is maintained well. it can.

  The greatest feature of the present invention is that a dental salt of an alginate impression material is blended with a metal salt having a low solubility in water within a specific range and an ionization tendency smaller than calcium. That is, when alginate and calcium sulfate, which is a gelling reagent, are kneaded in the presence of water, calcium ions are gradually released from the calcium sulfate immediately after kneading, and react with the alginate to cure. . However, when this curing reaction proceeds to some extent and the kneaded product becomes highly viscous, the liberation of calcium ions from the calcium sulfate is rapidly reduced, and the curability is lowered accordingly. As a result, the cured product thus obtained has not yet completed the curing reaction, and the gel strength at the stage of removing the impression material from the oral cavity cannot be sufficiently secured.

  In contrast, when the dental alginate impression material is mixed with a metal salt having a solubility in water at 20 ° C. of 0.1 to 1.5 g / L and an ionization tendency smaller than calcium, the operation period of the impression material After the elapse of time, it is possible to suppress a decrease in reactivity of the alginate at the end of the curing period. The reason is not clear, but the present inventors presume as follows. That is, the metal salt having a moderately low solubility in water suppresses the initial dissolution of the impression material, and gradually dissociates until the end of the curing period to release metal ions. Then, the metal ions dissociated at the end of the curing period promote the ionization of calcium from calcium sulfate because of its small ionization tendency, and the supply amount of calcium ions into the kneaded material at the end of the curing period It is presumed that the increase is related.

  In addition, the solubility of the metal salt in water is moderately small, and the state in which the initial dissolution of the impression material is kept low, the influence on the active reactivity is slight at the beginning of the kneading, Even when a curing retarder is blended, a good operation margin time ensured by this can be maintained well.

  Hereinafter, the components of the alginate impression material of the present invention will be described in detail.

  As (A) calcium sulfate used in the present invention, known ones used for conventional impression materials can be used without any limitation. Specific examples of those particularly preferably used include calcium sulfate dihydrate, calcium sulfate hemihydrate, calcium sulfate anhydrous, and the like. These calcium sulfates can be used alone or in combination.

  From the viewpoint of adjusting the curing time when kneading each component, it is preferable to use a combination of calcium sulfate dihydrate and calcium sulfate anhydrous. The blending ratio may be appropriately determined so as to achieve a desired curing time. (A) The total amount of calcium sulfate is 100, and dihydrate gypsum is preferably used in the range of 10% to 90%.

  Although it does not specifically limit as a compounding quantity of calcium sulfate, In the kneaded material of an impression material, the inside of the range of 10 mass parts-2000 mass parts is preferable with respect to 100 mass parts of (C) alginate monovalent salt, 100 mass parts- A range of 1000 parts by mass is more preferable.

  In the present invention, (B) the metal salt has a solubility in water at 20 ° C. of 0.1 to 1.5 g / L so as to dissolve and release metal ions even at the end of the curing period of the alginate impression material. Is used. Here, when the solubility in water is greater than 1.5 g / L, most of the impression material is dissolved at the initial stage of kneading of the impression material, and the action of liberating metal ions at the end of the curing period becomes insufficient. On the other hand, when the solubility in water is less than 0.1 g / L, the solubility is too low, and the release action of metal ions at the end of the curing period is not sufficient. In the present invention, the particularly preferable solubility of the (B) metal salt in water at 20 ° C. is 0.2 to 1.3 g / L.

  In the present invention, the metal salt (B) is also required to be made of a metal having an ionization tendency smaller than calcium. Thereby, the ionization of calcium from calcium sulfate is promoted by the metal ions released at the end of the curing period, and the curability of the impression material is enhanced. Examples of such a metal with a low ionization tendency include magnesium, aluminum, zinc, manganese and the like, and magnesium and aluminum are particularly preferable. Although the ionization tendency of sodium is smaller than that of calcium, in general, the metal salt has high solubility in water and does not satisfy the above-mentioned requirement for low solubility.

  As the acid that satisfies the requirements for low solubility in water when forming a salt with a metal having a low ionization tendency, phosphoric acid, pyrophosphoric acid, carbonic acid, or oxalic acid is usually applicable. Specifically, a metal salt that satisfies both the low solubility in water and the low ionization tendency (hereinafter also abbreviated as “low water solubility / low ionization tendency metal salt”) can be expressed as zinc carbonate (to water). Solubility 0.1 g / L), manganese oxalate (water solubility 0.2 g / L), gold oxalate (water solubility 1.1 g / L), magnesium phosphate (water solubility 0.4 g) / L), aluminum phosphate (solubility in water 0.1 g / L), magnesium pyrophosphate (solubility in water 0.2 g / L), magnesium oxalate (solubility in water 1.2 g / L), carbonic acid Examples include magnesium (1.5 g / l). Among these, magnesium phosphate or magnesium pyrophosphate is preferable from the viewpoint of a large effect of improving the curing activity at the end of the curing period. These low water solubility / low ionization tendency metal salts can be used alone or in combination of two or more.

  In the present invention, the blending amount of the above-described (B) metal salt having a low water solubility and low ionization tendency is not particularly limited, but in the kneaded material of the impression material, (A) 1 mass per 100 mass parts of calcium sulfate. Part-50 mass parts is preferable, and 5-30 mass parts is more preferable. (B) When the compounding amount of the metal salt is less than 1 part by mass with respect to 100 parts by mass of (A) calcium sulfate, the amount of liberated metal ions at the end of the curing reaction becomes insufficient, and the mechanical strength of the cured product Tend to decrease. Moreover, when the compounding quantity of (B) metal salt exceeds 50 mass parts with respect to 100 mass parts of (A) calcium sulfate, the release amount of metal ions in the initial stage of curing increases excessively, and the impression material There is a tendency that the operation surplus time becomes faster.

  In the present invention, (C) the monovalent salt of alginic acid can be used without particular limitation from known ones used in conventional alginate impression materials. Examples include i) alkali metal alginate such as sodium alginate and potassium alginate, and ii) ammonium alginate such as ammonium alginate and triethanolamine alginate. Among these alginates, it is preferable to use an alkali metal alginate from the viewpoints of availability, ease of handling, physical properties of the cured product, and the like. Moreover, two or more types of alginate can be mixed and used.

  It is preferable that the alginate is usually contained within the range of 2% by weight to 10% by weight in the kneaded product of the impression material. Therefore, in a powder type impression material, water is kneaded with water in such an amount that the alginate is 2 to 10% immediately before use. In the paste type impression material, the amount of alginate contained in the base paste is adjusted so that the content of the alginate is within the above range in the kneaded product. Further, the molecular weight of the alginate is not particularly limited, but in general, the molecular weight is preferably such that the viscosity of the aqueous solution containing 1% by weight of the alginate is in the range of 50 cps to 100 cps.

  In addition to the components described above, various additives can be blended into the alginate impression material as necessary. In order to ensure a good operation margin time, it is preferable to blend a curing retarder. The curing retarder can adjust (delay) the reaction rate between the alginate and the gelling agent. For this reason, the paste type etc. adjusts the curing time according to the work time required from the mixing and kneading of each component constituting the alginate impression material until the impression is taken in the oral cavity, and there is sufficient operating margin. Make it possible. In addition, the low water solubility / low ionization tendency metal salt blended in the present invention is sufficiently ensured by the action of the curing retarder at the beginning of kneading of the impression material because of its low solubility in water. As described above, it does not greatly affect the operation margin time.

  As the curing retarder, a known curing retarder can be used without limitation. Specifically, i) alkali metal phosphates such as trisodium phosphate, tripotassium phosphate, sodium pyrophosphate and sodium tripolyphosphate, ii) alkali metal oxalates such as sodium oxalate and potassium oxalate, iii) Examples include alkali metal carbonates such as sodium carbonate and potassium carbonate. Two or more kinds of curing retarders can be mixed and used.

  Although the compounding quantity of a hardening retarder can be suitably selected according to another compounding component, the hardening time etc. which are requested | required, it exists in the range of 1-30 mass parts with respect to 100 mass parts of (C) alginate monovalent salt. Is preferable, and the inside of the range of 3 to 15 mass parts is more preferable. By setting the blending amount of the curing retarder within the above range, it becomes easy to adjust the curing time in accordance with the working time, and the cured product can have good curability.

  Furthermore, examples of the additive include a filler, an inorganic fluorine compound, a metal oxide, an amino acid compound, an unsaturated carboxylic acid polymer, a fragrance, a coloring agent, an antibacterial agent, a preservative, and a pH adjuster. In the case where the impression material of the invention is a paste type alginate impression material, water, a poorly water-soluble organic solvent, and the like are further included.

  When using a filler, a well-known thing can be utilized without a restriction | limiting. As the filler, viscosity minerals such as diatomaceous earth and talc are preferably used, and metal or semimetal oxides such as silica and alumina can also be used. Although the compounding quantity of a filler is not restrict | limited in particular, The inside of the range of 50-2000 mass parts is preferable with respect to 100 mass parts of (C) alginate monovalent salt, and the inside of the range of 100-1000 mass parts is more preferable. .

  In addition, from the viewpoint of adjusting the strength of the cured impression material, and preventing the rough surface of the gypsum model during impression collection or gypsum model manufacture, inorganic fluorine compounds such as potassium titanium fluoride and potassium silicofluoride, magnesium oxide, and zinc oxide It is preferable to add a curing aid such as a metal oxide such as amino acid or an amino acid compound such as amino acid / formaldehyde condensate. Although these compounding quantities are not specifically limited, The inside of the range of 1-200 mass parts is preferable with respect to 100 mass parts of (A) calcium sulfate, and the inside of the range of 10-100 mass parts is more preferable.

  In addition, when the components constituting the alginate impression material are mixed and kneaded, an unsaturated carboxylic acid polymer is preferably blended in order to easily control the rate of change in viscosity.

  In addition, when using as a paste type impression material, these additives can be suitably added to either one or both of the base paste and the curing agent paste. For example, the curing retarder is preferably added to the curing material paste, and the filler is preferably added to both the base paste and the curing agent paste.

  As described above, the alginate impression material of the present invention can be used in either a powder type or a paste type depending on the packaging state. The powder type alginate impression material is a mixture of the above-mentioned powder components ((A) calcium sulfate, (B) metal salt, (C) alginic acid monovalent salt, curing retarder, filler, etc.), immediately before use. The dentists or dental hygienists use a predetermined amount of the impression material powder and water to make a paste and use it for impression. Here, water may be added to the product package as a separate package from the powder component constituting the alginate impression material, but it is usually preferred that the user of the alginate impression material be appropriately procured. Moreover, you may use the aqueous solution which melt | dissolved the various additives mentioned above instead of water. In this case, an aqueous solution of the additive is added to the product package of the alginate impression material in addition to the powder component.

  The mixing ratio Rn of the impression material powder and water (the amount of powder impression material used / the amount of water used [mass part / mass part]) is not particularly limited, but is usually 0.1 to 1. It is preferable to be within the range.

  On the other hand, the paste-type impression material is a base paste made into a uniform paste using a solution containing water in advance, such as the alginate and filler, and calcium sulfate, a curing retarder, a filler, etc. It consists of a hardener paste that has been made into a paste using a poorly water-soluble organic solvent, and is used for taking an impression after kneading and mixing them together in a specified amount using a kneading mixer etc. just before use. is there.

  When the impression material is a paste type, the mixing ratio Rm of the base paste to the hardener paste (amount of base paste used / amount of hardener paste [parts by mass / mass part]) during the kneading operation is Although it does not restrict | limit in particular, Usually, it is preferable to exist in the range of 1-4.

  It does not specifically limit as a manufacturing method of the alginate impression material of this invention, A well-known manufacturing method can be suitably selected according to the form by which an alginate impression material is provided on the market. For example, when the alginate impression material is a powder type, a uniform and non-uniform powder can be obtained by mixing and stirring the components constituting the powder in an arbitrary order. Moreover, when a powder type alginate impression material also has an additive aqueous solution in addition to the powder, each additive component other than water constituting the additive aqueous solution can be dispersed and dissolved in water in any order.

  Moreover, when the alginate impression material of this invention is a paste type, a base material paste and a hardening material paste can be manufactured using the well-known stirring mixer which can be utilized for paste manufacture. Here, as the stirring mixer, for example, a rotating container type mixing and kneading machine such as a ball mill, a ribbon mixer, a kneader, an internal mixer, a screw mixer, a Henschel mixer, a universal mixer, a Ladige mixer, a butterfly mixer, A fixed container type mixing and kneader having a horizontal axis or a vertical axis such as the above can be used. Furthermore, when manufacturing the base paste and the curing material paste, two or more kinds of the above-described various mixing kneaders can be used in combination.

  When using the alginate impression material of this embodiment, generally, after preparing a kneaded material from at least the alginate impression material of this embodiment, this kneaded material is placed on a dedicated tray. And the impression is extract | collected by press-contacting the kneaded material put on the tray to target objects, such as a tooth | gear. Thereafter, after the kneaded material from which the impression has been collected is cured to become a cured product, a post-process such as making a plaster model based on the cured product is further performed. Here, a well-known tray can be used as the tray without limitation, but a metal tray or a resin tray is generally used. Examples of the metal tray material include stainless steel, tin alloy, aluminum, brass that is plated or resin-coated, and the like. In addition, when the alginate impression material of this embodiment is used, the kneaded material is well held in any metal tray. Examples of the material for the resin tray include polymethacrylate.

The present invention will be described below in more detail with reference to examples. However, the present invention is not limited to the following examples.
<< Abbreviations for raw materials >>
Abbreviations of various raw materials used in the preparation of the alginate impression materials of Examples and Comparative Examples described later, and the solubility in water at 20 ° C. are as follows.
1. Metal salt P3Mg: Trimagnesium phosphate (0.4g / l)
P2Mg: Magnesium pyrophosphate (0.2 g / l)
PAl: Aluminum phosphate (0.1 g / l)
CO3Zn: Zinc carbonate (0.1 g / l)
CO3Mg: Magnesium carbonate (1.5 g / l)
C2O4Mg: Magnesium oxalate (1.2 g / l)
2, Alginate Alg-Na: Sodium alginate 3, Other P3Na: Trisodium phosphate FTiK: Potassium titanium fluoride MgO: Magnesium oxide fluid P: Liquid paraffin Dec13: Decaglyceryl triolate

<< Measurement of solubility >>
Moreover, about the solubility of (B) metal salt, it carried out as follows.
The object was added to 100 ml of distilled water so as to be saturated, and dissolved in a water bath at 20 ° C. by stirring for 24 hours. After the sample was filtered to remove insolubles, a calibration curve was prepared using a standard concentration reagent using ICP emission spectroscopy, and the amount of dissolved metal ions was quantified. Hereinafter, when the solubility of an object is shown, the solubility at 20 ° C. is simply expressed as solubility.

<< Evaluation method >>
An evaluation method of “curing time” and an evaluation method of “elastic strain and permanent strain” for the samples of Examples and Comparative Examples described later are as follows.
Measurement of “curing time”:
An impression material wrought product is placed on an acrylic plate (71 mm × 71 mm) bonded to a flat cylinder (outer diameter 50 mm, inner diameter 45 mm, height 8 mm), the upper surface is scraped off, and a stopwatch is started. An acrylic rod (diameter 6 mm × 100 mm) is inserted into this surface and the operation of pulling up is repeated. The time until the impression material surface roughness (surface roughness due to partial curing) due to the insertion and lifting of the acrylic rod was measured. In addition, the same test was performed 3 times and the average value was made into hardening time. Here, (B) the curing time of 129 seconds in Comparative Example 1, which does not contain a metal salt having a low water solubility and low ionization tendency and has a good curing margin time by mixing an appropriate amount of a curing retarder Those having a curing time of 120 seconds or longer on the basis of the standard can be evaluated as having particularly excellent curing allowance time. Moreover, what is hold | maintained at the length for 105 seconds or more can be evaluated that it has a favorable hardening allowance time.

Measurement of “elastic strain” and “permanent strain”:
A cylindrical mold A having an inner diameter of 31 mm, an outer diameter of 38 mm, and a height of 16 mm is placed on an acrylic plate and filled with an impression material kneaded material. Then, the inner system is 13 mm, the outer diameter is 25 mm, and the height is 20 mm. The cylindrical mold B was inserted, the upper surface was pressed with another acrylic plate, fixed with a small vise, immersed in 37 ° C. water, and the stopwatch was started. After 3 minutes, the sample was taken out of the water, the impression material cured body sample (13 mmφ × 20 mm) was removed from the mold B, and set in a compression tester (“PEACOCK” product name) manufactured by Seiki. The compression test was started by the following procedure after 1 minute from setting in the compression tester. First, a load of 100 gf / cm ² is applied, the stopwatch is started, and the dial gauge when 30 seconds have elapsed is read (A). At 60 seconds, a load is gently applied until 70 seconds so that the total weight becomes 1000 gf / cm ^2, and the dial gauge at 100 seconds is read (B). Further, at 130 seconds, a load of 100 gf / cm ² is applied again, and the dial gauge after 160 seconds is read (C). The elastic strain (εe) and permanent strain (εp) were determined from the following equations from the A, B, and C values. In addition, the same test was performed 3 times and the average value was made into elastic strain and permanent strain.

Elastic strain (εe) = (A−B) / 20 × 100 (%)
Permanent strain (εp) = (A−C) / 20 × 100 (%)

Here, those having an elastic strain value of 14% or less can be evaluated as having particularly excellent elastic strain, and those having an elastic strain value of 15% or less can be evaluated as having good elastic strain. Similarly, a permanent strain value of 4% or less can be evaluated as having a particularly excellent permanent strain, and a permanent strain value of 5% or less can be evaluated as having a good permanent strain.

Example 1
(A) 72 g of anhydrous gypsum and 28 g of dihydrate gypsum as calcium sulfate, (B) 5 g of P3Mg as a metal salt, 34 g of liquid paraffin and 12 g of decagrin as a solvent, and MgO and FTiK as curing aids 13 g of each, 3 g of P3Mg as a curing retarder and 70 g of diatomaceous earth as a filler were weighed for 1 hour using a small kneader (Aiko mixer manufactured by Aiko Sangyo Co., Ltd.) to prepare a curing material paste. (C) 29 g of Alg-Na as the alginate, 510 g of distilled water as the water, and 11 g of diatomaceous earth as the filler were weighed and stirred for 1 hour using a small kneader to prepare a base paste. The obtained hardening material paste and base material paste were kneaded by an alginate impression material automatic kneader (“AP mixer II” manufactured by Tokuyama Dental Co., Ltd.) so that the mixing ratio Rm of the base material paste to the hardening material paste was 2. The obtained kneaded product was used for measurement of curing time, and measurement of elastic strain and permanent strain.

Examples 2-10
Except that the composition of the alginate impression material was changed to the contents shown in Table 1, the base paste and the curing agent paste were adjusted in the same manner as in Example 1, and the obtained kneaded product was used to measure the curing time. In addition, elastic strain and permanent strain were measured.

Comparative Examples 1-10
Except for changing the composition of the alginate impression material to the contents shown in Table 2, the base paste and the curing agent paste were adjusted in the same manner as in Example 1, and the obtained kneaded product was used to measure the curing time. In addition, elastic strain and permanent strain were measured.
(Evaluation results)
Tables 1 and 2 show the compositions of the alginate impression materials of Examples 1 to 9 and Comparative Examples 1 to 10. In addition, Table 3 shows the measurement results of the curing time, elastic strain, and permanent strain of the samples of Examples 1 to 10 and Comparative Examples 1 to 10.

  Examples 1 to 10 were adjusted to satisfy all the requirements of the present invention, but in each case, they had a sufficiently long curing time, good elastic strain and permanent strain. It was.

  On the other hand, Comparative Example 1 is a case where the (B) metal salt of low water solubility / low ionization tendency of the present invention was not blended, but when adjusted to have a sufficiently long curing time, Both permanent set increases and the cured product becomes soft.

  Comparative Example 2 was an attempt to improve elastic strain and permanent strain by further increasing the amount of curing aid in the composition of Comparative Example 1 in which (B) a metal salt having a low water solubility and low ionization tendency was not blended. However, the curing time is shortened by increasing the amount of the curing aid.

  Comparative Example 3 is a composition of Comparative Example 2, in which the amount of the curing retarder is further increased and the physical properties are optimized by delaying the curing time. Strain and permanent set become large (hardened body is soft).

  In Comparative Example 4, in order to delay the curing time, (A) dihydrate gypsum which is calcium sulfate was reduced, and the curing time was adjusted to the optimum value by the blending amount of the curing retarder. A balance between elastic strain and permanent strain cannot be achieved.

  Comparative Example 5 to Comparative Example 7 are aluminum acetate (solubility: 3.0 g / L) and aluminum oxalate (solubility: 1.9 g / L) instead of (B) the metal salt having a low water solubility and low ionization tendency of the present invention. This is the case where the solubility exceeds 1.5 g / L, but the metal salt dissolves in water immediately after kneading the curing material paste and the base material paste, which affects the curing time. Further, the curing time and the cured body strength are not compatible in a preferable range.

  In Comparative Examples 8 to 9, when metal silicate (insoluble in water) or aluminum silicate (solubility 0.01 g / L) less than 0.1 g / L is used, metal ions are not supplied. The strength of the cured product cannot be improved.

  Similarly, Comparative Example 10 is a case where the amount of diatomaceous earth is greatly increased, but even in this case, the elastic strain is not improved and the permanent strain is lowered, so that satisfactory strain physical properties cannot be obtained.

Claims (5)

(A) calcium sulfate,
(B) a metal salt having a solubility in water at 20 ° C. of 0.1 to 1.5 g / L, an ionization tendency smaller than calcium, and (C) alginate monovalent salt,
A dental alginate impression material characterized by comprising: (B) A metal salt having a solubility in water at 20 ° C. of 0.1 to 1.5 g / L and an ionization tendency smaller than calcium is phosphate, pyrophosphate, carbonate, or oxalate. The dental alginate impression material according to claim 1. (B) The metal salt having a solubility in water at 20 ° C. of 0.1 to 1.5 g / L and an ionization tendency smaller than calcium is magnesium phosphate or magnesium pyrophosphate. 2. Dental alginate impression material according to 2. (B) The amount of the metal salt whose solubility in water at 20 ° C. is 0.1 to 1.5 g / L and whose ionization tendency is smaller than that of calcium is (A) 1 part by mass per 100 parts by mass of calcium sulfate It is 50 mass parts, The dental alginate impression material as described in any one of Claims 1-3. Furthermore, the dental alginate impression material as described in any one of Claims 1-4 containing (D) hardening retarder.