JPH06121801A - Ring lining material for dental casting - Google Patents

Abstract

PURPOSE:To provide a ring lining material for dental casting which enables the performing of a wet type casting equivalent to that using an asbestos ribbon without containing asbestos. CONSTITUTION:In a ring lining material for dental cast molded in a sheet being bonded with a synthetic resin emulsion using a ceramic fiber, a glass fiber and an organic powder as main component, a permeation processing is applied with a nonionic surfactant (with H. L. B. value of 9-13).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dental casting ring lining material which is used by lining it inside a casting ring in dental casting.

[0002]

2. Description of the Related Art A ring lining material used for dental casting is used as a cushioning material on the inside of the dental casting ring as a cushioning material in order to compensate for shrinkage caused when the molten metal cast in the dental casting ring is cooled to room temperature. It is used as a lining. Conventionally, asbestos ribbons obtained by cutting asbestos-based asbestos paper into strips have been used as ring lining materials of this type.Recently, ceramic paper mainly composed of some ceramic fibers such as silica / alumina fibers has been used. Came to be used.

[0003]

When a tooth (cavity) affected by caries or a tooth that has fallen off is to be restored by dentistry, an alloy is cast to produce an inlay, a crown or the like. In this casting, a precision casting method called the lost wax method is used. This is because if the precision is poor, the cast inlay or crown cannot be reliably attached to the patient's teeth.

However, even in the lost wax method, the dental alloy shrinks by about 1.5 to 2.3% before it is cooled to room temperature after being solidified in the mold, so that the mold material shrinks during casting and during casting. It is necessary to inflate enough to compensate for When casting the molten alloy, it is necessary for the mold to be about 1.5 to 2.3% larger than the size of the wax pattern, so that the mold material is set to expand and heat. The mold material is formed by burying a pattern formed of wax in a casting ring to solidify the mold material and then heat-dewaxing in an electric furnace to form the mold.

Therefore, a ring lining material for absorbing expansion of the casting material is provided on the inner peripheral surface of the casting ring. This ring lining material is stripped and lined on the inner peripheral surface of the casting ring. Therefore, the ring lining material is required to fit the casting ring, absorb expansion of the casting material during condensation and expansion during heating, and maintain a sheet shape even during heating and not collapse into a cotton shape. Asbestos ribbon has been conventionally used as a material satisfying such requirements.

In the actual dental casting work, water absorption of the ring lining material becomes an important characteristic. That is, in the work of burying the wax pattern in the mold material, the mold material powder and water are mixed at a predetermined weight ratio immediately before the work,
The mud-shaped mold material thus obtained is poured into a mold ring containing a lining material. After that, the mold material is dried and solidified by standing at room temperature. When the water content in the mold material is absorbed by the lining material during the period from pouring to the mold ring until it is dried and solidified, the mixing ratio changes and therefore the casting characteristics and casting workability have the effects as listed below. Exert. (1) The water absorption of the lining material changes the water mixing ratio of the casting material, which changes the expansion coefficient during drying and solidification. (2) The water absorption of the lining material causes a partial change in the water mixing ratio of the casting material, causing cracks during drying and solidification. (3) If the water absorption rate of the lining material is high, the above (1),
In addition to the problem described in (2), casting workability also deteriorates. That is, water is absorbed immediately after pouring the mold material, and when the mold material expands, the lining material is compressed and the contained water is discharged, forming a film of water on the upper surface of the mold material, so-called "water floating" occurs. To do. As a result, the drying and solidifying time becomes long and the working time becomes long. (4) Although the lining material absorbs water, when the water absorption speed is slow, it gradually absorbs water while the mold material dries and solidifies, so that a dent occurs in the central part of the upper surface of the mold material, causing so-called "dents". , The mold material layer on the upper part of the wax pattern becomes thin and causes damage.

Asbestos ribbons that have been conventionally used as lining materials also have water absorption, but have a density of 0.8 g /
Since it is relatively high at about cm ³ , its water absorption is not strong. As a numerical value showing water absorption, for example, if 0.5 cc of water is dropped on asbestos ribbon, it will take about 15-40 before it penetrates.
Takes seconds. Since the asbestos ribbon has such a water absorbing property, it is made to contain water before pouring the mold material so as not to absorb too much water of the mold material in the dental casting work. In addition, when water is included too much, “water floating” occurs, so the water content is adjusted to an appropriate level.
The actual work involves immersing the asbestos ribbon in water for 1-2 seconds. In this way, if the casting mud is poured after preliminarily containing water, the dent is less likely to occur, and a good drying and solidifying work without floating of water can be performed. Conventionally, such a method has been widely adopted and is called a “wet method”. Many dental technicians have adopted a wet method that uses asbestos ribbons, and in order to make fine adjustments to the mold dimensions according to the patient's tooth mold, experience can be used to adjust the amount of water to be pre-hydrated, I have adjusted the mixing ratio of the mold material.

On the other hand, contrary to the wet method, by eliminating the water absorption of the ring lining material and making it water repellent, water is prevented from entering and exiting and accurate casting is performed without changing the water mixing ratio of the casting material. There is also the idea of doing so, and such a method is called the “dry method”. In this case, vaseline has been applied to the asbestos ribbon, or waterproof treatment has been performed with silicone spray or the like. However, such a work of imparting water repellency is complicated, and when an asbestos ribbon is used, it has been almost always performed by a wet method.

As described above, asbestos ribbons have been widely used in dental casting, but asbestos is carcinogenic in recent years, its use is prohibited in the United States for building materials. It has become a social problem such as regulation. Also in dentistry, there is an increasing demand for materials that replace asbestos. Under these circumstances, ring linein materials containing asbestos-free ceramic fibers such as alumina / silica fibers have also come to be marketed.

These ceramic fiber-based lining materials contain ceramic fibers as a main component and synthetic resin such as acrylic resin or natural pulp as a binder. The density of ceramic paper is generally 0.4 g / cm ³ or less and has better cushioning properties than asbestos ribbons, and even if it is thinner than conventional asbestos ribbons, it does not suppress expansion when the mold material is condensed or expanded when heated. Moreover, there are advantages such as sufficient heat resistance. However, when the binder is heated and the binder disappears, the lining material in the casting ring collapses like a cotton, and although it does not suppress the expansion of the mold material, it does not have a buffering force and easily cracks in the mold, causing casting defects. There are drawbacks. In order to improve such defects, in addition to the organic binder, an appropriate amount of an inorganic binder such as glass fiber, silica sol, or alumina sol is blended so as to maintain a proper strength even after the organic binder disappears and to prevent casting defects. It has also come to be done.

Focusing on the water absorption, the inorganic fibers themselves such as ceramic fibers and glass fibers are hydrophilic, and when the binder used is a hydrophilic material such as natural pulp, a hydrophilic (water absorbing) lining material. When a water repellent material such as synthetic resin is used, the degree of water repellency of the lining material also becomes stronger depending on the amount. As mentioned above, the density of ceramic paper is 0.4 g / cm ³ or less and 1 of asbestos ribbon.
/ 2 or less, the water absorbency is extremely large when the water repellent material is not used, and when water drops are dropped, the water absorbs instantly. When immersed in water, absorb more than 300 parts by weight of the original weight almost instantly. Therefore, when the casting material is poured into the ring by the wet method in the same manner as the asbestos ribbon, water floating occurs. When a synthetic resin is used as the organic binder, the greater the amount of synthetic resin added, the stronger the water repellency. Since 5 parts by weight or more is usually added to obtain the required working strength, the ring lining material made of synthetic resin hardly absorbs water and is used as a dry lining material. Also,
Some dry lining materials are treated with a silicone-based or fluorine-based water repellent to ensure water repellency.

As described above, the conventional ceramic lining material is excellent in heat resistance and cushioning property, but does not have the proper water absorption property of the asbestos ribbon. That is, it has either an extremely high water absorption rate or, on the contrary, hardly absorbs water, and there has been no ceramic ring lining material that can be used in the same operation as the wet method using asbestos ribbon which has been widely used in the past. . Many dental technicians have skills gained from experience in wet casting using asbestos ribbons, not including asbestos,
Further, there has been a demand for a ceramic-based ring lining material which has an appropriate water absorption property and can be used by a wet method operation similar to that of an asbestos ribbon.

[0013]

DISCLOSURE OF THE INVENTION The ring lining material for dental casting of the present invention contains no asbestos at all, and in order to obtain appropriate water absorption and castability similar to those of an asbestos ribbon, a ceramic is used. Dental casting ring lining material composed mainly of fiber, glass fiber and inorganic powder, which was bound with synthetic resin emulsion and formed into a sheet, was permeated with a nonionic surfactant. Characterize. The nonionic surfactant of H. L. B. A value of 9 to 13, preferably 11 to 12, is suitable.

In the dental casting, when the wax pattern is heated and dewaxed, it is heated at 700 to 800 ° C. in an electric furnace, and therefore ceramic fibers having a heat resistant temperature of 1000 ° C. or higher are used as a heat resistant aggregate. In addition, glass fiber and inorganic powder are added so that the synthetic resin does not collapse into a cotton shape after the synthetic resin disappears during heating. The fiber diameter of the ceramic fiber is relatively large, about 3 μm, the shape retention force due to the entanglement of the fiber is weak, and when the binding force due to the organic binder is lost, the ceramic fiber alone collapses into a cotton shape. When the inorganic powder is held here, the fiber matrix is reinforced and the collapse can be prevented. When glass fiber is further added, the glass fiber softens and sinters at 400 to 700 ° C., so that it further exerts a reinforcing effect at high temperatures. For example, soda glass, phosphate glass, borate glass, or the like is used. The intention of blending inorganic powders, typified by alumina powders, is to make the texture of the sheet dense and smooth in addition to the filling and reinforcing effect of the fiber matrix, and to reduce the porosity by improving the density and control the water absorption described later. To make it easier.

Al ₂ O ₃ which is usually used as the ceramic fiber having a heat resistance of 1000 ° C. or more according to the present invention.
In addition to ceramic fibers having a weight ratio of / Si ₂ O of 0.4 to 0.6, alumina fibers, zirconia fibers, shirasu fibers, and potassium titanate fibers can be used.
30 to 60 parts by weight. Also, the appropriate amount of glass fiber is
10 to 50 parts by weight.

In order to obtain working strength, a synthetic resin emulsion having an excellent adhesive force is suitable as the organic binder.
Acrylic resin and vinyl acetate resin are suitable as the synthetic resin emulsion, and the compounding amount thereof is suitably 5 to 20 parts by weight. If the amount is less than 5 parts by weight, the working strength is low and problems such as cutting when slitting into strips occur. In addition, if it is 20 parts by weight or more, the strength is too strong and it does not fit flexibly on the inner peripheral surface of the casting ring.In addition, when the casting material is dried and solidified at room temperature, it has no cushioning property and suppresses expansion of the casting material, Poor compatibility with the supporting part. Incidentally, a synthetic resin may be used as an organic material in combination with a conventionally used natural pulp to give a soft texture.

The sheet formed by blending the materials as described above contains 5 to 20 parts by weight of the synthetic resin, and therefore hardly absorbs water. Therefore, in the present invention, a penetrating agent is attached to give a suitable penetrability in order to obtain a lining material that has an appropriate water absorption equivalent to that of an asbestos ribbon and can be used in a wet method. When imparting permeability to a water repellent material, an ionic surfactant typified by alkylbenzene sulfonate having a high permeability is generally used. However,
With such an ionic surfactant with strong penetrating power, the water absorption of the sheet after the permeation treatment changes greatly with a slight difference in the amount of adhesion, and it is difficult to obtain an appropriate water absorption like asbestos ribbon. Is.

On the other hand, when a nonionic surfactant having a weak penetrating power is used, the change in the water absorption of the sheet due to the difference in the adhered amount is small, and the desired proper permeability can be easily obtained by the operation of the adhered amount. To be The nonionic surfactant H.I.
L. B. A value of 9 to 13 is suitable. H. L. B. Value is 8
The following is not suitable because it is not completely dissolved in water. H.
L. When the B value is 14 or more, the permeability becomes too strong, and it becomes difficult to control the water absorption of the sheet after the permeation treatment. As the nonionic surfactant, for example, polyoxyalkyl phenyl ether, polyoxyethylene alkyl ether,
Polyoxyethylene fatty acid ester can be used, and the amount of adhesion is suitably 0.3 to 5 parts by weight.

[0019]

[Function] A sheet is prepared under the conditions described above,
H. L. B. The water absorbency of a sheet that has been subjected to a permeation treatment with a nonionic surfactant with a value of 9 to 13 takes 10 to 40 seconds until it permeates when 0.5 cc of water is dropped, which is almost the same as that of an asbestos ribbon. Therefore, even if the mold material is put in by the same wet method operation as in the case of using asbestos ribbon, the same drying and solidification as in the case of using asbestos ribbon can be performed. That is, "water floating" does not occur and "dents" are small. As for the casting characteristics, when the mixture is dried and solidified, the change of the water content of the casting material is small, and the deformation such as dents is small, so that the casting mold can be manufactured accurately. In addition, when the wax pattern is heated and incinerated in an electric furnace, it does not suppress the heat expansion of the mold material and does not collapse into a cotton shape even after the organic binder disappears. Compatibility of the restoration with the defective abutment is also good.

[0020]

EXAMPLES Next, examples of the present invention will be described together with comparative examples. Example 1 30 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 20 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
30 parts by weight of alumina powder, bleached kraft pulp (NBKP) 20
Disaggregate parts by weight in water. To this, 7 parts by weight of acrylic resin (Toagosei PDLA-160W) and a polymer coagulant were further added, paper was made by a usual method, and dried to prepare a sheet having a thickness of 0.7 mm. Next, H. L. B. A 0.5% aqueous solution of a nonionic surfactant (Daiichi Kogyo Seiyaku EP-120A) having a value of 12 was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain H.264. L.
B. A sheet (Sample A) having 3.0 parts by weight of the solid content of the nonionic surfactant having a value of 12 was obtained.

Example 2 50 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 25 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
25 parts by weight of the alumina powder of is disintegrated in water. To this, 15 parts by weight of vinyl acetate resin (Kanebo NSC iodozole) and a polymer flocculant were added, paper was made by the usual method, and dried to a thickness of 0.7.
mm sheets were made. Next, H. L. B. A 1.0% aqueous solution of a nonionic surfactant (Daiichi Kogyo EP-110) having a value of 11 was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain H.264. L. B. A sheet (Sample B) to which 5.0 parts by weight of the solid content of the nonionic surfactant having a value of 11 was attached was obtained.

Comparative Example 1 30 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 20 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
30 parts by weight of alumina powder, bleached kraft pulp (NBKP) 20
Disaggregate parts by weight in water. To this, 7 parts by weight of acrylic resin (Toagosei PDLA-160W) and a polymer coagulant were further added, paper was made by a usual method, and dried to prepare a sheet having a thickness of 0.7 mm. Next, H. L. B. A 0.5% aqueous solution of a nonionic surfactant (Daiichi Kogyo Seiyaku ET-147) having a value of 14 was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain H.264.
L. B. A sheet (Sample C) having 2.0 parts by weight of the solid content of the nonionic surfactant having a value of 14 was obtained.

Comparative Example 2 30 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 20 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
30 parts by weight of alumina powder, bleached kraft pulp (NBKP) 20
Disaggregate parts by weight in water. To this, 7 parts by weight of acrylic resin (Toagosei PDLA-160W) and a polymer coagulant were further added, paper was made by a usual method, and dried to prepare a sheet having a thickness of 0.7 mm. Next, H. L. B. A 0.7% aqueous solution of a nonionic surfactant (Daiichi Kogyo Seiyaku ET-147) having a value of 14 was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain H.264. L.
B. A sheet (Sample D) having 4.0 parts by weight of the solid content of the nonionic surfactant having a value of 14 was obtained.

Comparative Example 3 50 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 25 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
25 parts by weight of the alumina powder of is disintegrated in water. To this, 15 parts by weight of vinyl acetate resin (Kanebo NSC iodozole) and a polymer flocculant were added, paper was made by the usual method, and dried to a thickness of 0.7.
mm sheets were made. Next, a 0.1% aqueous solution of an alkylbenzene sulfonate-based surfactant (Daiichi Kogyo Seiyaku Neocor), which is an ionic surfactant, was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain an ionic surfactant. A sheet (Sample E) having a solid content of 1.5 parts by weight attached was obtained.

Comparative Example 4 50 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 25 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
25 parts by weight of the alumina powder of is disintegrated in water. To this, 15 parts by weight of vinyl acetate resin (Kanebo NSC iodozole) and a polymer flocculant were added, paper was made by the usual method, and dried to a thickness of 0.7.
mm sheets were made. Next, a 0.2% aqueous solution of an alkylbenzene sulfonate-based surfactant (Daiichi Kogyo Seiyaku Neocor), which is an ionic surfactant, was prepared, and the obtained sheet was subjected to dipping treatment and further dried to obtain an ionic surfactant. A sheet (Sample F) having a solid content of 3.0 parts by weight attached was obtained.

Comparative Example 5 30 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260), 20 parts by weight of C glass fiber having a fiber diameter of 4 μm, average particle diameter of 1.5 μm
30 parts by weight of alumina powder, bleached kraft pulp (NBKP) 20
Disaggregate parts by weight in water. To this, 3 parts by weight of fine cellulose fibers (Daicel Chemical MFC) and a polymer flocculant were added, paper was made by a usual method, and dried to obtain a 0.7 mm-thick sheet (Sample G).

Comparative Example 6 H. L. B. An attempt was made to prepare a 0.7% aqueous solution of a nonionic surfactant (Daiichi Kogyo Seiyaku EA-70) having a value of 8, but it was not dissolved in water and the aqueous permeation treatment was impossible.

Next, each of the obtained sheet samples was used as a ring lining material and cast by a usual wet casting method, and the degree of "water floating" and "dent" at the time of drying and solidifying the casting material and the degree of casting after casting. Observe the occurrence of casting burrs in the cast,
Furthermore, the suitability of the cast body was evaluated as good or bad. The water absorption of the sheet was also measured, and the results are shown in Table 1. Asbestos ribbon that has been conventionally used as Comparative Example 7 (Sample H) (manufactured by ORIVEST CORPORATION, thickness 0.8 mm, density 0.
Similar tests were conducted for 76 g / cm ³ ) and the results are shown in Table 1. The test method is shown below. (1) The sample is cut into a width of 32 mm and a length of 89 mm, and the height is 35 m
It is lined inside a casting ring with an inner diameter of 29 mm and immersed in water for 1 second together with the casting ring, and shaken 3 to 4 times to remove excess water. (2) A casting ring backed with a sample is fixed to a truncated cone in which an existing crown type wax pattern is erected. (3) Further, the mold material powder and a specified amount of water are mixed, and the mold material kneaded into a cream is poured into the ring to embed the wax pattern. As the mold material, a wet gypsum-based mold material having a water mixing ratio of 0.38 was used. (4) Time required from the injection of the mold material into the ring to the drying (time until the water on the upper surface of the mold material disappears)
To measure. Also, at this time, observe for the presence of "water floating",
"Dent amount" is measured by a depth meter. (5) After being sufficiently dried and singulated, it is heated and incinerated at 700 ° C. to cast a dental gold-silver-palladium alloy, cooled to room temperature, taken out from the mold, and visually observed for cast burrs. (6) Regarding compatibility, see A. D. A full-crown type and MOD inlay type in A standard No. 2 are cast in the same manner as above, the cast body is taken out of the mold, and then returned to the prototype and the compatibility is good or bad depending on the degree of the gap with the prototype. Evaluate. (7) Regarding the water absorption of the sheet, 0.5 cc of water was dropped on the horizontally placed sheet sample, and the time until the water absorption was measured.

[0029]

[Table 1]

As is clear from Table 1, in the case of the examples of the present invention, even if casting is performed by the same operation as in the wet casting method using asbestos ribbon, "water floating" and "dents" are generated when the casting material is dried and solidified. It was confirmed that there was no problem, no casting burrs were generated in the cast body after casting, and the suitability of the cast body was good.
On the other hand, it is difficult to obtain an appropriate water absorption similar to that of the asbestos ribbon in the case of the one that has been subjected to the permeation treatment with the strongly ionic surfactant. In addition, a material made of only a hydrophilic material without using a synthetic resin has too strong water absorption and causes "water floating".

[0031]

EFFECTS OF THE INVENTION The ring lining material for dental casting according to the present invention is capable of wet casting equivalent to asbestos ribbon, although it does not contain asbestos. That is, since it has been permeated with a nonionic surfactant, it has an appropriate degree of water absorption equivalent to that of asbestos ribbons, and the same operation as that of asbestos ribbons for the work of drying and solidifying the mold material in wet casting. You can In addition, since it has an appropriate cushioning force against expansion of the mold material at room temperature or heating, casting defects such as casting burrs do not occur in the mold body, and the compatibility of the cast restoration with the defective abutment part is also good. is there. As described above, since the wet casting work equivalent to that conventionally performed can be performed, the casting technique in the wet method using the asbestos ribbon, which many dental technicians have experience, can be applied as it is.

Claims (2)

[Claims] 1. A ring lining material for dental casting, comprising ceramic fibers, glass fibers, and inorganic powder as main components, which is bound with a synthetic resin emulsion and formed into a sheet shape, which is impregnated with a nonionic surfactant. A ring lining material for dental casting, which has been subjected to. 2. The surfactant is H.264. L. B. Value is 9 ~
The ring lining material for dental casting according to claim 1, which is 13 nonionic surfactants.