JPH1087419A - Gypsum composition for dentistry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dental gypsum composition capable of improving the water resistance of the cured product, thereby enabling the composition to produce gypsum models excellent in storage stability without causing the surface erosion of the models, the changes of fine shapes, the roughness generation of the surfaces, etc., on various kinds of washing treatments on dental technical operations. SOLUTION: This gypsum composition for dentistry comprises 100 pts.wt. of a dental gypsum composition comprising semi-hydrated gypsum, a curing retarder and, if necessary, a curing accelerator and a curing expansion-inhibiting agent, 0.01-0.5 pt.wt. of ethylene tetrefluoride resin, and further 0.001-0.05 pt.wt. of one or more kinds of anionic surfactants selected from alkylbenzene sulfonates and alkyl sulfates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a material for a dental model,
The present invention relates to a powdery dental gypsum composition used for denture implanting materials and the like, and more particularly, to a dental gypsum capable of improving the water resistance of a cured product by water repellency of a mixed ethylene tetrafluoride resin. It relates to a composition.

[0002]

2. Description of the Related Art Conventionally, in the dental field, inlays, crowns, bridges, partial dentures,
BACKGROUND ART When preparing various dental restorations such as a complete denture, a dental gypsum composition is widely used as an important material as a mold material. For example, a plaster model material for producing a working model or a jaw model used for producing a wax pattern or a wax denture, etc., and a wax denture is buried in a dental flask when producing a resin denture base. It is used as a material for implanting dentures.

[0003] These dental gypsum compositions usually contain α-hemihydrate gypsum (hard gypsum) and / or β-hemihydrate gypsum (burning gypsum), which is a hemihydrate gypsum, and a curing retarder. And the like, and provided in the form of a powder. At the time of use, a dentist or a technician collects a predetermined amount of the powder of the dental gypsum composition and water for kneading into a small rubber ball (rubber ball), kneads it with a gypsum plaster, and mixes it with gypsum. When used as a model after making a slurry, it is poured into a negative mold that has taken an impression of the oral cavity and hardened to produce a working model or jaw model that reproduces the state of the oral cavity, and used for embedding dentures In this case, it is used for the purpose of injecting into a dental flask to bury a wax denture. Working models and jaw models are the basis for making dental restorations, and of course have high dimensional accuracy and smooth surfaces, especially when making metal restorations. There is also a demand for strength and hardness that can withstand use under severe conditions in which a prototype wax pattern is directly produced on a working model or a jaw model using a chisel.

The curing mechanism of a dental gypsum composition is, as shown below, a curing by changing hemihydrate gypsum into dihydrate gypsum by reacting with water and crystallization. CaSO ₄ 1 / 2H ₂ O + 3 / 2H ₂ O → CaSO ₄ 2H ₂ O Since this curing mechanism is cured by water, the cured product is weak to moisture and, as a result, lacks water resistance. This is an important issue. In the actual technical operation, erase the marked part with colored pencils for designing dental restorations on working models and jaw models, remove wax debris attached at the time of creating wax pattern patterns, remove stains on the model surface, When cleaning the buried surface after flowing wax,
Washing with running water or hot water or washing by spraying high-pressure steam from a steam cleaner is frequently performed, but the surface is eroded due to the weakness of the cured body to moisture and insufficient water resistance. The shape of the working model or jaw model changes,
The edges are rounded and the surface of the hardened body is roughened, causing dimensional changes in the most important and basic working models and jaw models, resulting in inaccurate dental restorations. Causing the phenomenon.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and improves the water resistance of a cured body of a dental gypsum composition, so that it can be washed with running water or hot water at the time of a technical operation. Prevents erosion of the model surface due to lack of water resistance, changes in detail shape, surface roughness, etc. due to lack of water resistance even when washing with high-pressure steam in a steam washer, and dimensional changes to working models and jaw models It is an object of the present invention to develop a dental gypsum composition capable of obtaining a dental restoration having excellent precision without causing a dental restoration.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a predetermined amount of a tetrafluoroethylene resin has been mixed in advance in a dental gypsum composition powder. It was found that the water repellent property of the tetrafluoroethylene resin extremely effectively acts on the improvement of the water resistance of the cured product of the dental gypsum composition cured by the reaction between hemihydrate gypsum and water, and the present invention Was completed. Further, one or two selected from the group consisting of alkylbenzene sulfonates and alkyl sulfates are added to the dental gypsum composition.
It has also been found that mixing more than one type of anionic surfactant improves kneading operability.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dental gypsum composition according to the present invention comprises a mixture of hemihydrate gypsum and a setting retarder.
With respect to 0 parts by weight, the first invention in which 0.01 to 0.5 parts by weight of the tetrafluoroethylene resin was mixed, and 100 parts by weight of a mixture composed of hemihydrate gypsum and a setting retarder, 0.01 to 0.5 parts by weight of the tetrafluoroethylene resin, 0.5 parts by weight and one or two selected from the group consisting of alkylbenzene sulfonates and alkyl sulfates
A second invention in which 0.001 to 0.05 parts by weight of at least one kind of anionic surfactant is mixed, and a mixture 10 composed of hemihydrate gypsum, a curing retarder, a curing accelerator and / or a curing expansion inhibitor.
A third invention in which 0.01 to 0.5 part by weight of a tetrafluoroethylene resin is mixed with respect to 0 part by weight, and a mixture comprising hemihydrate gypsum, a curing retarder, a curing accelerator and / or a curing expansion inhibitor.
For 100 parts by weight, 0.01 to 0.5 parts by weight of a tetrafluoroethylene resin, and 0.001 to 0.05 parts by weight of one or more anionic surfactants selected from the group consisting of alkylbenzene sulfonates and alkyl sulfates And the fourth aspect of the present invention.

When ethylene tetrafluoride is polymerized in an aqueous solution, a fine particulate ethylene tetrafluoride resin having an average particle size of about 0.05 to 5 μm is obtained. The molecular chains of this fine resin have low intermolecular cohesive force, and become fine spider web fibers when subjected to slight compressive / shear stress. When such a spider web-like fiber tetrafluoroethylene resin is dispersed in a dental gypsum composition and kneaded with water, the spider web fiber becomes a spider web fiber. Exists in such a form as to penetrate into the needle-like crystals of gypsum dihydrate in the cured body of the dental gypsum composition, preventing water from entering the gaps between the acicular crystals, and as a result, the cured body Can be improved in water resistance.

Specifically, during the production of a dental gypsum composition, a powdery ethylene tetrafluoride resin is added into a mill during the grinding process of hemihydrate gypsum, and the shear and compression stress of the mill is reduced to tetrafluoride. It also applies to ethylene resin. In the tetrafluoroethylene resin, the C--C bond of the main chain of the molecular chain is strong, whereas the intermolecular attraction to other molecular chains is extremely small. The ethylene fluoride molecules are finely fiberized into spider web fibers. These fibers are present in such a state that they are entangled with the fine particles in the gypsum composition, and are uniformly distributed to capture the fine particles. This phenomenon was also confirmed by scanning electron microscope observations, which showed a phenomenon in which the particles of the gypsum composition agglomerated in appearance, but this was caused by the usual operation of granulating particles. Unlike the fine agglomeration of the above, since the powder is lightly agglomerated in a state where fine particles are captured in a network of fine fibers, a phenomenon that affects the characteristics of the dental gypsum composition does not occur. When the dental gypsum composition is kneaded with water, the fibrous tetrafluoroethylene resin dispersed in the powder of the dental gypsum composition becomes a needle-like crystallization in the cured product. It exists so as to fill the gaps between the gypsums and prevents the intrusion of water between the crystal grains, thereby improving the water resistance of the gypsum cured product. However, if the mixing amount of the tetrafluoroethylene resin was less than 0.01 part by weight, the improvement of the water resistance was insufficient, so the lower limit of the mixing amount of the tetrafluoroethylene resin was set to 0.01 part by weight.

On the other hand, the reason why the upper limit of the mixing amount of the tetrafluoroethylene resin is set to 0.5 part by weight is as follows. As described above, when tetrafluoroethylene resin is subjected to shearing and compressive stress, it is finely fiberized into spider web-like fibers and uniformly entangled with fine particles in the dental gypsum composition. It is possible to exist in a distributed manner. However, when the mixing amount of the tetrafluoroethylene resin is excessive, it acts not only on capturing fine particles but also on larger particles, causing a phenomenon in which powder agglomerates into granules. The step of discharging the dental gypsum composition powder from the mill is performed by opening the mill lid and receiving the powder falling from the discharge port with a hopper while rotating the mill. When the ethylene resin is agglomerated in a granular form, the amount of powder discharged from the outlet of the mill decreases, and as a result, the discharge time increases as much as possible. The powder remaining in the mill continues to be pulverized by the rotation when discharging from the mill, but the efficiency of mill pulverization is determined by the amount of the powder and the relative ratio of the mill balls, and the ratio of the mill balls is large. Indeed, the milling efficiency increases exponentially, so the discharge time from the mill is prolonged, so that the powder finally discharged from the mill is excessively pulverized compared to the powder discharged first and has no properties at all. As a result, the characteristics vary greatly, and it becomes impossible to supply a stable product. For these reasons, the upper limit of the mixing amount of the ethylene tetrafluoride resin is limited to 0.5 part by weight in view of the limit of the discharge time from the mill.

[0011] The tetrafluoroethylene resin has a very strong water repellency, and when a dental gypsum composition containing the same is kneaded with water, the operational sensation in terms of kneadability referred to as "adhesion with water". Adversely affect Specifically, the wettability between the powder and water deteriorates, the powder and water cannot be mixed in a short time, and the powder floats on the water, making it difficult to perform the kneading operation. This property depends on the performance of the dental gypsum composition itself.
It does not directly affect the properties, but causes problems in operability during use, including kneadability. In order to solve this problem, it is possible to improve the wettability between the powder and water by mixing an anionic surfactant to improve the kneadability.

As the alkylbenzene sulfonate as an anionic surfactant, sodium dodecylbenzenesulfonate or the like is used, and as the alkyl sulfate, sodium lauryl sulfate, potassium lauryl sulfate, sodium myristyl sulfate, sodium cetyl sulfate, stearyl sulfate. Sodium or the like is used.

The mixing amount of the anionic surfactant is 0.001.
If the amount is not less than part by weight, the improvement of “compatibility with water” has been confirmed, so the lower limit of the mixing amount is specified as 0.001 part by weight. On the other hand, when the mixing amount is increased, “fitness with water” during kneading is improved, but it has been confirmed that the “storage stability”, “curing time” and “compression strength” are adversely affected. The upper limit of the mixing amount of the anionic surfactant was specified as 0.05 part by weight.

The hemihydrate gypsum used in the dental gypsum composition according to the present invention is α-hemihydrate gypsum, β-hemihydrate gypsum,
There are combinations of α-hemihydrate gypsum and β-hemihydrate gypsum. The compressive strength of the cured product is significantly affected by the water mixture ratio, and the lower the water mixture ratio, the higher the compressive strength is obtained. Therefore, when high strength is required, such as when used as a model material, the ratio of α-hemihydrate gypsum alone or in combination with α-hemihydrate gypsum and β-hemihydrate gypsum When a material with a low water-mixing ratio is often used, and moderate strength and easy crushing are required, such as when used as a denture burying material in the case of denture base preparation, β-hemihydrate gypsum A single mixture or a combination of α-hemihydrate gypsum and β-hemihydrate gypsum having a high water-mixing ratio with a large proportion of β-hemihydrate gypsum is used.

The operability and physical properties of dental gypsum compositions are set according to the purpose of use such as a model material and a material for embedding dentures. However, since hemihydrate gypsum itself hardens rapidly, it is usually used. A set retarder has been added. As the setting retarder, salts such as citrate, borate, carboxylate and acetate, and known setting retarders comprising water-soluble polymers such as starch, gum arabic, carboxymethylcellulose and gelatin are used. It is possible and usually contained in 0.00001 to 0.2 parts by weight based on 100 parts by weight of the dental gypsum composition.

When a fine adjustment of the curing time is required, a curing accelerator may be used.
As the hardening accelerator, a known hardening accelerator such as an inorganic acid such as NaCl or K ₂ SO ₄ or a fine powder of dihydrate gypsum is used, and usually contained in a dental gypsum composition in an amount of 0.001 to 2% by weight. You. When the setting expansion value needs to be adjusted, a known setting expansion inhibitor composed of a soluble potassium salt such as potassium sulfate, potassium chloride, potassium tartrate or the like is used as the setting expansion inhibitor, and usually, dental gypsum is used. 0.01 to 1 part by weight is contained in 100 parts by weight of the composition. In addition, a known coloring agent or a lightening material may be contained as necessary.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples of the dental gypsum composition according to the present invention.

Examples 1 to 9 and Comparative Examples 1 to 5 The compositions and properties of the examples are summarized in Tables 1 and 2. Tables 3 and 4 show the composition and properties of each comparative example.

<< Preparation of Samples >> In each of the examples and comparative examples, using a blending ratio shown in the table, using a test blending ball mill having a content of 100 liters, the total weight of the dental gypsum composition was crushed by a scale of 50 kg.・ Samples were prepared by mixing.
First, α-hemihydrate gypsum alone, β-hemihydrate gypsum alone, or a mixture of α-hemihydrate gypsum and β-hemihydrate gypsum shown in Tables 1 and 3, and a mixture of hemihydrate gypsum and ethylene tetrafluoride resin were used. The powder was put into a mill and ground until the hemihydrate gypsum showed a predetermined particle size distribution. After pulverization, properties such as curing time and consistency indicating the fluidity of the gypsum sludge are measured, and a curing retarder and, if necessary, a curing accelerator and a curing expansion inhibitor are added according to the results. The surfactant was mixed. After mixing, the mixture was discharged from the mill and stored in a hopper. The powder of the ethylene tetrafluoride resin was subjected to shearing and compressive stress in the pulverization and mixing steps, turned into fine fibers, and was uniformly dispersed in the powder of the dental gypsum composition. From the dental gypsum composition stored in the hopper, 1 kg was randomly sampled 5 times for each property test, and a sample of 5 kg in total was collected and used as a sample.

<< Characteristics test method >>
Physical properties were measured by the methods specified in S T6605 “Dental gypsum” and JIS T6604 “Dental plaster”.

A method for evaluating the water resistance of a cured product of a dental gypsum composition has not been established in JIS standards or the like.
Not specifically defined. However, when the cured body is immersed in running water, erosion is observed in a portion below the running water surface, and the erosion near the running water surface is most eroded. Therefore, the water resistance can be evaluated based on the degree of the erosion. Therefore, this time, evaluation was made by the following method. Using a rubber mold, the dental gypsum compositions of Examples and Comparative Examples are kneaded with a predetermined amount of mixed water to prepare a cured product of a square of 15 × 15 × 100 mm. After storing in a thermostat at 37 ° C. for 24 hours, the cured product is allowed to cool to room temperature, and the lengths of the four sides at the center of the test sample are measured with a projector. The cured product is placed upright on a tray (25 × 35 × 6 cm) having a volume of about 5.2 liters and placed at random positions. Each embodiment,
Five cured bodies are arranged for each comparative example. The tray is tilted by about 3 °, water (flow rate: 1 liter / min) is flowed into the tray, and the lower half of the cured body is kept immersed in running water. After one hour, the cured body is taken out. Store in a thermostat at 37 ° C for 24 hours and dry. After cooling to room temperature, the length of each side of the cured body is measured again with a projector, the difference from the length of each side before the test is calculated, and the water resistance is evaluated based on the degree of erosion by running water.

The method of the forced deterioration test for evaluating the storage stability is as follows: 1 kg of the dental gypsum composition of each of the Examples and Comparative Examples is collected in a polyethylene bag having a thickness of 0.1 mm, and after sealing, at 37 ° C.
After storing in a thermo-hygrostat at 100% humidity for 60 days, the curing time is measured, and the storage stability is evaluated based on the difference from the curing time before the forced deterioration test.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

The effect of improving the water resistance by mixing the tetrafluoroethylene resin can be confirmed by comparing the composition and characteristic values in Tables 1 to 4. As is clear from the table, in each example, 0.01 to 0.5 parts by weight of the tetrafluoroethylene resin is mixed, and the tetrafluoroethylene resin is present in the gaps between the needle-like crystals of the cured body of the dental gypsum composition. Thus, the infiltration of moisture is prevented to improve the water resistance. In Example 3, in which the mixing amount of the tetrafluoroethylene resin was large and the anionic surfactant was not mixed, the evaluation of “compatibility with water” which is an index of kneadability was evaluated as “difficult”. However, clinical use was possible.

On the other hand, in Comparative Examples 1, 4, and 5 in which the tetrafluoroethylene resin was not mixed, and in Comparative Example 2 in which the mixing amount was less than the lower limit of the present invention, erosion of the cured product due to low water resistance and running water was observed. Largely, as a result, the working model, jaw model, and buried surface of the dental prosthesis, which are the basics for producing a dental restoration in clinical practice, are likely to be deformed during cleaning, resulting in a dental restoration with poor dimensional accuracy. . When Examples 1 and 2 and Comparative Examples 1 and 2 are compared, the main components are the same, and the only difference is the amount of the mixed tetrafluoroethylene resin. From this comparison, it was confirmed that the mixing of the tetrafluoroethylene resin with the dental gypsum composition significantly improved the water resistance of the cured product, and the lower limit of the mixing amount was confirmed to be 0.01 part by weight. Was.

In Comparative Example 3 in which the mixing amount of the tetrafluoroethylene resin exceeds the upper limit of the present invention and a large amount of the anionic surfactant is mixed, 0.8 part by weight of the tetrafluoroethylene resin is mixed. "Familiarity with water" which is also an index of reconciliation
Is evaluated as “normal” and has the same kneading operability as the current gypsum composition product, but the dental plaster composition is milled due to excessive mixing of the ethylene tetrafluoride resin. In the process of discharging from the mill, the phenomenon of agglomeration of the powders occurs and the amount discharged from the outlet of the mill decreases, and the rotation of the mill for discharging causes the powder remaining in the mill to pulverize and excessive grinding In addition, a vicious cycle occurs in which coagulation progresses and the discharge from the mill is delayed, and the difference between the powder characteristics, especially the curing expansion value and curing time, becomes large between the initial stage and the final stage of the discharge. The actual operation became impossible due to the long time. As a result of examining the range in which the difference in curing expansion and curing time between the initial stage of discharge and the end of discharge in the mill discharge has no problem in clinical application,
It has been found that the upper limit of the mixing amount of the tetrafluoroethylene resin is suitably 0.5 part by weight.

Further, in Examples 1 to 3 in Table 1, the mixing amount of the ethylene tetrafluoride resin, which is a substance having strong water repellency, was 0.1%.
When the amount is as low as 01 parts by weight (Example 1), even if an anionic surfactant is not blended, the property of "fitting with water", which is an index of kneading ability, is "normal" and the dental gypsum composition of the current product is used. It has almost the same kneadability as the product, but when the mixing amount of the tetrafluoroethylene resin becomes 0.1 part by weight (Example 2), the property of "migration with water" which is an index of kneadability is It is evaluated as "somewhat difficult". Further, when the mixing amount of the tetrafluoroethylene resin is increased to reach the upper limit of 0.5 parts by weight (Example 3) of the present invention, the evaluation of "adhesion with water" as an index of kneading becomes "difficult". . In the evaluation of “fitness with water”, which is an index of this relevance, the evaluations of “normal”, “somewhat difficult” and “difficult” are:
It is compared with the dental gypsum composition of the current product,
"Normal" is equivalent to the current product, "Slightly difficult" is slightly inferior to the current product, and "Difficult" is considerably inferior to the current product, Clinical use was to the extent possible.

As described above, the kneadability is reduced by mixing a tetrafluoroethylene resin with the dental gypsum composition, but Examples 4, 5, 7, and 9 improve this property. For this reason, an anionic surfactant was mixed, and it was confirmed that the kneadability was improved thereby. Specifically, in the comparison between Example 2 and Example 4, the difference in blending is the mixing amount of the tetrafluoroethylene resin and the presence or absence of the mixing of the anionic surfactant. In Example 2, the mixing amount of the tetrafluoroethylene resin was 0.1 part by weight, and there was no mixing of the anionic surfactant, and the “compatibility with water” was “slightly difficult”. On the other hand, in Example 4, the “fitness with water” is “normal” even though 0.2 parts by weight of the ethylene tetrafluoride resin is mixed more than in Example 2. This is clearly the mixing effect of the anionic surfactant. Similarly, in the comparison between Example 3 and Example 5, the mixing effect of the anionic surfactant becomes clear. The difference between Example 3 and Example 5 was only the presence or absence of the mixing of the anionic surfactant, and the “compatibility with water” of Example 3 which was not mixed was “difficult” but was mixed. In Example 5, which was "normal", the improvement of kneadability was confirmed.

In Example 4, the mixing amount of the anionic surfactant was very small and 0.001 part by weight. However, since the effect of improving the kneading operability was confirmed from the comparison with Example 2, the anionic surfactant was used. It was confirmed that the lower limit of the mixing amount of the agent was appropriately 0.001 part by weight. A large amount of an anionic surfactant is most notably caused by a delay in the curing time after the forced storage (a decrease in storage stability). From the test results of the conventional product, it has been verified that there is no problem in clinical use if the delay of the curing time after forced storage is up to 6:00 seconds. Although the mixing amount of the anionic surfactant of Example 5 is 0.05 part by weight, which is the upper limit of the present invention, the delay of the curing time after forced storage is 3:00 seconds, which is not a problem in practical use. Even when the amount of other anionic surfactant mixed is large (Example 7), the delay of the curing time is 3 minutes.
It was within 00 seconds. However, in Comparative Example 3, since the amount of the anionic surfactant was 0.1 part by weight, which was more than the upper limit of the present invention, the delay time of the curing time after forced storage was extremely large as 18:00 seconds, and the storage stability was poor and the dimensions were poor. It is difficult to produce a dental restoration with excellent accuracy. The mixing of an excessive amount of an anionic surfactant in this way results in a large delay in the curing time after forcible storage of the dental gypsum composition, and is not practical. From the above results, it was confirmed that the upper limit of the mixing amount of the anionic surfactant was appropriately 0.05 part by weight.

[0033]

As described in detail above, the dental gypsum composition according to the present invention is obtained by forming the tetrafluoroethylene resin into fine spider web-like fibers and uniformly dispersing it in the dental gypsum composition powder. When dispersed in water, there is a fiberized ethylene tetrafluoride resin that fills the gaps between the needle-like gypsum crystals in the process of curing the dental gypsum composition when mixed with water. As a result, the effect of preventing moisture from entering the gaps between the crystals and improving the water resistance of the dental gypsum cured product can be obtained. As an attendant effect, the mixing of the tetrafluoroethylene resin and the fiberization in the pulverizing step prevent the fine powder from scattering due to the fine particle capturing effect, and the scattering of the dental gypsum composition powder during the kneading operation with water. Is also obtained. In addition, with respect to the deterioration of kneading operability due to the addition of a highly water-repellent tetrafluoroethylene resin, one or more shades selected from the group consisting of alkylbenzene sulfonates and alkyl sulfates are used. The problem can be solved by adding an ionic surfactant. The value of the dental gypsum composition according to the present invention having such various effects which contributes to the dental field is extremely large.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 27:18

Claims (4)

[Claims] 1. A dental gypsum composition characterized in that 0.01 to 0.5 part by weight of an ethylene tetrafluoride resin is mixed with 100 parts by weight of a mixture comprising hemihydrate gypsum and a setting retarder. 2. 100 parts by weight of a mixture consisting of hemihydrate gypsum and a setting retarder, 0.01 to 0.5 parts by weight of an ethylene tetrafluoride resin, and an alkylbenzene sulfonate or an alkyl sulfate selected from the group consisting of: A dental gypsum composition characterized by being mixed with 0.001 to 0.05 parts by weight of one or more anionic surfactants. 3. A method comprising mixing 0.01 to 0.5 parts by weight of an ethylene tetrafluoride resin with respect to 100 parts by weight of a mixture comprising hemihydrate gypsum, a curing retarder, a curing accelerator and / or a curing expansion inhibitor. A dental gypsum composition characterized by the following: 4. 100 parts by weight of a mixture comprising hemihydrate gypsum, a curing retarder, a curing accelerator and / or a curing expansion inhibitor, 0.01 to 0.5 part by weight of an ethylene tetrafluoride resin, an alkylbenzene sulfonate, A dental gypsum composition characterized by being mixed with 0.001 to 0.05 parts by weight of one or more anionic surfactants selected from the group consisting of alkyl sulfates.