JPH11209219A - Alginate impression material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alginate impression material having slight swelling by water absorption and shrinkage, etc., and capable of suppressing weight change of gel substance even when a gel substance after obtaining impression is immersed and stored in water by making the impression material include a specific two kinds of calcium sulfates and disodium hydrogen phosphate. SOLUTION: This alginate impression material comprises 5-30 wt.%, preferably 5-25 wt.%, more preferably 7-23 wt.% gelling agent comprising a mixture of (A) calcium sulfate dihydrate with (B) calcium sulfate hemihydrate and used in (1:19) to (19:1), preferably (1:9) to (9:1), more preferably (1:4) to (9:1) weight ratio of the component A to the component B, (C) 0.01-2.0 wt.%, preferably 0.02-1.8 wt.% more preferably 0.05-1,5 wt.% disodium hydrogen phosphate as a gelation adjusting agent, (D) 3-25 wt.% alginate, (E) filler and (F) as necessary, a strain controlling agent, a compatibility-improving agent, a dust preventing agent, a coloring agent, a flavoring agent, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an alginate impression material (hereinafter sometimes referred to as an "impression material"). More specifically, the present invention relates to an alginate impression material which has a moderate deformation distortion when the impression material is molded, has a small weight change after the molding, and has a high use value.

[0002]

2. Description of the Related Art Alginate impression materials are based on the fact that alginate reacts with a gelling reactant to form a gel-like cured product, and is mainly composed of alginic acid, a gelling hardener, a filler and the like. Composition. Such an alginate impression material is suitably used mainly for molding at the time of restoration and restoration of teeth and other moldings.

[0003] Alginate impression materials are classified into two types, powder type and paste type, according to their product form. The powder type is a powder mixture composed mainly of alginate, a gelling agent, a filler, etc.
A dentist or a dental hygienist kneads a specified amount of impression material powder and water to form a paste, which is used for obtaining an impression. On the other hand, a paste-type impression material is composed of a main agent in which alginate and an inert powder or the like are made into a homogeneous paste in a solution containing water in advance, and a hardener mainly containing a powdery or paste-like gelling reactant. Immediately before use, both are kneaded and mixed by a prescribed amount, and used as a homogeneous paste for impression taking. In any case, the gel-like cured product of the alginate impression material used for impression acquisition contains a large amount of water.

[0004] Since the impression obtained by using the alginate impression material contains a large amount of water, the dimensional change of the gel body with time is unavoidable due to external conditions. In normal air, the impression material gel body is significantly shrunk and deformed due to evaporation of water. Therefore, injection of a model agent immediately after taking an impression is recommended as a method for obtaining a model having good dimensional accuracy. However, in actual dental care sites, this method is often not adhered to due to treatment procedures and the like.

As a measure for keeping the dimensional change relatively small, there is a method in which an impression material gel body is allowed to stand in a desiccator at a relative humidity of 100%. However, storage space and special equipment are required,
Keeping these conditions hygienic at all times is often avoided because of the complicated work. Furthermore,
As a method of suppressing shrinkage deformation in the air, a method of immersing the gel body in water may be used.However, in this method, moisture enters the molecular gap of the impression material gel body, and unreacted ions Swelling, shrinking, and the like, such as moving from the gel body to the immersion water, cause irregular dimensional changes. That is, although this method is a very simple method, there are many problems when trying to obtain a model with stable dimensional accuracy.

On the other hand, for the alginate impression material, a paste-like impression material is pressed against a mold (original) to be obtained, removed from the original after gelation, and a molding agent such as gypsum is injected into the gel-like hardened material and cured. Obtain a model with the same shape as the rear prototype, but the prototype has various shapes and the maximum diameter of the prototype may be larger than the opening for removing the mold, so the impression material gel body is required to be distorted by external force . However, on the other hand, an accurate model cannot be obtained if the mold is deformed due to the weight of the molding agent such as gypsum. Therefore, it is desired that an appropriate amount of distortion is caused by external force.

[0007]

The impression molded as described above is a gel body containing a large amount of water, and when left in a room under normal conditions, large shrinkage deformation is caused by drying.
As a simple storage method for preventing this phenomenon, immersion storage in water is performed, and an object of the present invention is to provide an impression material in which deformation due to water absorption or the like at this time is reduced. Also, the impression material is used for various types of molding, but it is necessary to remove the impression material gel body by partially distorting the impression material gel body depending on the shape of the object to be molded. A model material is prepared by injecting a mold material such as gypsum into the obtained impression material gel body, but it is necessary that the fine portion be a gel body that does not deform due to the weight of the mold material or the like. Therefore, an object of the present invention is to provide an alginate impression material having an elastic strain suitable for such contradictory requirements.

[0008]

Means for Solving the Problems The present inventors have set forth the above-mentioned object of the present invention and, if necessary, water absorption swelling and shrinkage of an impression material gel body caused when the impression material gel body is immersed in water. As a result of diligent studies on providing an alginate impression material in which the impression material gel body is distorted by an appropriate amount due to external force, a combination of calcium sulfate dihydrate and hemihydrate is used as a gelling agent for the impression material. And, by using disodium hydrogen phosphate as a gelling regulator, even if the gel body after taking the impression is immersed and stored in water, water absorption swelling, shrinkage, etc. can be reduced and the weight change of the gel body can be suppressed, In addition, they have found that they have an appropriate elastic strain which is easy to operate at the time of removal from the original mold and at the time of injection of the molding agent, and has no fear of deformation.

That is, the gist of the present invention is that (A) calcium sulfate dihydrate, (B) calcium sulfate hemihydrate and (C)
An alginate impression material comprising disodium hydrogen phosphate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The alginate impression material of the present invention has the same components as a normal alginate impression material and contains an alginate, a gelling agent, a filler, and the like. The first feature is to use calcium sulfate dihydrate and (B) calcium sulfate hemihydrate.

The combined weight ratio of the two is usually 1:19.
To 19: 1. This weight ratio is preferably from 1: 9 to 9: 1, and more preferably from 1: 4 to 9: 1. In this ratio, when the amount of dihydrate is larger than this range, it is difficult to obtain the effect of the present invention of reducing the water absorption,
If the amount of hemihydrate is more than this range, the gelation reaction rate will be slow, and when clinically used as an impression material for molding teeth, etc., the retention time in the oral cavity will be longer, and the burden on the patient will be increased. It grows large and is not suitable for actual use.

The total content of the above gelling reactants is usually 5 to 30% by weight of the impression material, preferably 5 to 25% by weight, more preferably 7 to 23% by weight. If the amount used is less than this range, the impression material surface may appear to be gelled, but the gelation is insufficient, causing a problem in other performances as an impression material such as a decrease in gel strength. On the other hand, if the used amount is larger than the range, the bulk of the impression material powder becomes small, for example, and the actual used amount increases, so that it is not economical. It should be noted that other known gelling reagents can be used in combination within a range that does not impair the present invention.

Further, in the alginate impression material of the present invention,
As a gelling regulator, sodium dihydrogen phosphate is a second feature. The amount of disodium hydrogen phosphate used is
In the impression material, it is usually 0.01 to 2.0% by weight, preferably 0.02 to 1.8% by weight, and more preferably 0.05% by weight.
~ 1.5% by weight. The gelling agent is used to make the impression material into a uniform paste, take an appropriate working time until it is pressed against the original mold, and adjust the degree of cross-linking after pressing to add appropriate softness to the gel body. Have been. Although the gelation of the alginate impression material partially reacts rapidly to form a gel body, the reaction gradually proceeds thereafter, and the degree of crosslinking increases, resulting in a hard gel body. If the amount of disodium hydrogen phosphate used is less than this range, the gel body is too soft, giving the user anxiety of deformation. On the other hand, if it is larger than this range, the gelation time becomes extremely long, and as described above, it is not suitable for practical use. In the range that does not impair the present invention, a known gelling regulator other than disodium hydrogen phosphate, for example, a phosphate, silicate, carbonate, oxalate, or the like of an alkali metal such as sodium or potassium may be used in combination. Is also possible.

The alginate impression material of the present invention conforms to the composition of an ordinary alginate impression material except for the characteristic components of the gelling agent and the gelling agent. For example, alginates include water-soluble salts such as sodium, potassium, ammonium and triethanolamine, and the content is usually preferably 3 to 25% by weight. As the filler, diatomaceous earth, talc, silica, aluminum hydroxide,
Other metal oxides and the like can be mentioned, but diatomaceous earth is preferable, and more specifically, a combination of disc-shaped and rod-shaped diatomaceous earth is used. Furthermore, various additives such as a strain regulator, a compatibility modifier, a dust inhibitor, a coloring agent, a fragrance and the like can be appropriately compounded.

The method for producing the impression material of the present invention is not particularly limited, and may be appropriately selected from known methods. For example, put all the raw materials into the mixer at the same time,
Mixing may be performed, or divisional mixing may be performed according to the purpose. Further, the quantitative composition of the impression material in the present specification indicates a composition in terms of powder excluding the solvent in the case of the paste type.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which do not limit the present invention in any way. Examples 1 and 2, Comparative Examples 1 and 2 A predetermined mixing operation was performed according to the mixing ratio shown in Table 1. The resulting impression material was evaluated the next day under room temperature conditions of 23 ° C. and 50% relative humidity. Gel time and elastic strain are JIS
-6505 (dental alginate impression material).

The weight change of the impression material gel body was such that a cylinder having an inner diameter of 30 mm and a height of 5 mm was filled with an impression material paste so as not to contain air bubbles and the like, and the upper and lower portions were sandwiched between smooth plates to gel the surface smoothly. The gel body weight was accurately weighed. 40.0 after weighing
The gel body was immersed in g of distilled water, taken out after a predetermined time, gently wiped off water adhering to the surface with a filter paper, weighed accurately again, and shown as a weight change ratio with respect to the initial weight.

The compatibility (Ra) with anhydrite is obtained by taking an impression of a smooth polyethylene terephthalate surface with an impression material,
After gently washing with water, the gypsum mud was injected and hardened, and after 30 minutes from the injection, the center line average roughness of the impression material interface of the gypsum which was removed from the mold and left overnight in the room was measured. The measurement was performed with Surfcom 570A, and the measurement length was 2.50 mm.

Table 1 shows the measurement results. In addition, in order to adjust the gel time to an appropriate time as an impression material, sodium pyrophosphate was used in combination as a gel time adjuster, and the composition was appropriately increased / decreased, but no influence was observed on the water absorption. In each of the examples, the rate of change in weight was able to be kept small as compared with the above. In particular, in Example 2, it was less than 1%. Further, the compatibility (Ra) with anhydrite was also good.
This was considered to be because the influence on the hardening of the anhydrite was reduced due to a decrease in the movement of water and unreacted ions between the impression material gel body and the anhydrite. In addition, the elastic strain was on the order of 15%, which was a value that did not apply an excessive force to the prototype at the time of demolding, and had sufficient hardness without the possibility of deformation upon injection of the mold. This means that, for example, in the operation of molding teeth in the oral cavity, the burden on the patient during lapse of time is small, and the operator has a moderate softness, so that the operation is easy, and the mold is used immediately after demolding. Even when a certain gypsum was poured, the hardness was such that a good model could be obtained without deformation of the details due to the weight of the gypsum or the setting expansion.

On the other hand, in Comparative Example 1, a large weight increase of 2% or more was observed even after immersion for 10 minutes. In addition, 60
After 5 minutes, a weight increase of 5% was observed, and it was considered that the impression material gel body was swollen. It was predicted that the model obtained from this impression gel body would be a small model compared to the original dimensions obtained. In Comparative Example 2, since the elastic strain is large and the strain is caused by a relatively small force, the user may be deformed at the time of the demolding operation from the original mold and the subsequent injection of the mold.

[0021]

[Table 1]

[0022]

According to the alginate impression material of the present invention, the weight change of the gel body over time can be suppressed even when the gel body obtained by the impression is immersed in water. Therefore, at the actual medical site, etc., when the model agent cannot be injected immediately due to the work procedure, or when it is desired to inject and use the model agent in an impression obtained by a plurality of patients in terms of work efficiency, It is possible to suppress water absorption swelling and shrinkage even when immersed in water and stored. The method of storage by immersion in water can be used as the simplest method since special equipment and maintenance are not required, and can be prepared immediately when needed, and the working efficiency is improved.

In the alginate impression material of the present invention,
By reducing the movement of water and unreacted ions on the contact surface of the impression material gel body, the influence on the hardening of the anhydrite injected into the obtained impression surface is reduced, and the obtained model surface is also selected and Become. Further, since the elastic strain of the impression material gel body is in an appropriate range, the demolding operation after gelation is easy, and there is no possibility of deformation even when the mold is injected, so that an accurate model can be obtained.

Claims (4)

[Claims] (A) calcium sulfate dihydrate, (B)
An alginate impression material comprising calcium sulfate / hemihydrate and (C) disodium hydrogen phosphate. (A) calcium sulfate dihydrate and (B)
The weight ratio with calcium sulfate / hemihydrate is 1:19 to 1
The alginate impression material of claim 1, wherein the ratio is 9: 1. 3. A calcium sulfate dihydrate and (B)
The total content of calcium sulfate and hemihydrate is 5 to 30% by weight
The alginate impression material according to claim 1 or 2, wherein: 4. The alginate impression material according to claim 1, wherein the content of (C) disodium hydrogen phosphate is 0.01 to 2.0% by weight.