JPH0734809B2 - Dental casting ring lining material - Google Patents

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 Prior Art Strip-shaped ring liners used in dental casting contain the shrinkage that occurs when the molten metal is cast in order to accurately fit the cast restoration to the parenchymal defect in the oral cavity and when it is cooled to room temperature. For the purpose of compensation, the dental casting material is used as a cushioning material while being lined inside the dental casting ring without suppressing the setting expansion and heat expansion. The ring lining material used for such a purpose is called a cushioning material for casting or a relining material for casting in dentistry.

Conventionally, asbestos paper containing asbestos as a main component has been used as a ring lining material, and recently, ceramic paper containing a part of ceramic fibers as a main component has come to be used.

[0004]

[Problems to be Solved by the Invention] In recent years, asbestos is carcinogenic, so the use of asbestos in building materials is prohibited in the United States, and it is regulated in Japan. Has become. In dentistry, there is an increasing demand for materials that replace asbestos.

On the other hand, as a substitute for the ring lining material containing asbestos as a main component, a ceramic fiber ring lining material containing alumina silicate fiber as a main component is commercially available. This ceramic fiber-based ring lining material contains ceramic fibers as a main component and a synthetic resin such as acrylic resin or natural pulp as a binder.

[0006] Such a ceramic fiber ring lining material has a cushioning property sufficient for use in dentistry, and does not suppress the expansion of the casting material at the time of setting or heating, but The heated ring lining material in the work ring collapses into a cotton shape, and despite the casting ring, it shows the state of ringless casting. That is, cracks easily occur in the mold, causing casting defects. This casting defect also adversely affects the compatibility with the defective abutment portion.

That is, in order to restore a tooth (cavity) affected by caries or a tooth that has fallen off in dentistry, an alloy is cast to form an inlay, a crown or the like. A precision casting method called a lost wax method is used for casting. 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 heating. It is necessary to expand to compensate for When casting the molten alloy, the mold must be 1.5 to 2.3% larger than the size of the wax pattern, which causes the mold material to congeal and thermally expand. The mold material is formed by burying a pattern made of wax in a casting ring, condensing the mold material, and then heating and dewaxing in an electric furnace to form a mold.

Therefore, a ring lining material for absorbing the expansion of the mold material is provided on the inner peripheral surface of the casting ring. This ring lining material is lined inside the casting ring in a strip shape. Therefore, it is required to fit a casting ring, absorb expansion of the mold material at the time of setting and heating, and maintain the heated ring lining material in a sheet shape and not collapse into a cotton shape. Further, the ring lining material needs water repellency so as not to absorb water in order to eliminate the variation in expansion due to water absorption expansion of the casting material.

However, although the above-mentioned ceramic fiber as a main component and synthetic resin or natural pulp as a binder does not suppress expansion of the mold material,
Fitting to the inner peripheral surface of the casting ring, the heated ring lining material collapses into a cotton shape and cracks easily occur in the mold,
There is a problem that a casting defect occurs, or the water content of the casting material is absorbed by the ring lining material, and the expansion of the casting material varies.

[0011]

The present invention does not contain asbestos at all, does not absorb the moisture of the casting material, and a strip sheet fits on the inner peripheral surface of the casting ring to cause expansion and heating at the time of setting of the casting material. Absorbs expansion at the time, the heated ring lining material does not collapse into cotton like a sheet and does not easily crack in the mold so that casting defects such as casting burrs do not occur in the cast body In addition, as a result of diligent examination of a ring lining material that also has good compatibility with the defect abutment part of the cast restoration, 400 to 400% of conventional ceramic fibers and inorganic powders with heat resistance of 1000 ° C or more have been used. Softening and sintering at 700 ℃, adding glass component that becomes a matrix of ceramic fibers and inorganic powder, and the organic binder is thermally decomposed Adhesive strength at room temperature with an inorganic binder that exhibits adhesive strength at a temperature of 200 ℃ or more Similar to that of asbestos paper, it also has an appropriate buffering effect by using an organic binder that exerts the above effect, does not suppress expansion during mold setting and heating, and has a suitable strength to form casting burrs. The present invention has been completed by finding a ring lining material that does not generate.

That is, according to the present invention, a ring lining material made into a sheet by adding an inorganic binder and a synthetic resin emulsion to an inorganic powder such as alumina silicate ceramic fiber and glass fiber having a heat resistance of 1000 ° C. or more and alumina powder is used. It contained no asbestos, did not cause casting defects such as casting burrs in the cast body, and had good compatibility with the abutment portion.

With the ring lining material according to the invention,
The reason why a cast restoration with good compatibility without the occurrence of casting burrs can be obtained is that when the mold material condenses at room temperature, the ceramic fiber, glass fiber, and inorganic powder provide adequate cushioning properties and the organic binder provides adequate cushioning properties. It has sufficient tensile strength to prevent condensation expansion.

Further, when the pattern of wax or resin buried in the mold is incinerated from the solidified mold, an inorganic binder which does not suppress the thermal expansion of the mold and has an adhesive effect at 200 ° C. or higher. The effect of does not cause cracks in the mold.

The glass fiber of the present invention is softened at 700 ° C. or lower, and the thermal transformation temperature of quartz or cristobalite aggregate contained in the mold material, that is, quartz 573 ° C. and cristobalite 200 to 30.
Although it shows a large expansion at 0 ° C, it shows a role of giving an appropriate buffering action and strength to the large expansion due to the thermal transformation of aggregate. For example, soda glass, phosphate glass, borate glass or the like is used.

Further, since the thermal transformation temperature of quartz and custobalite contained in the mold material is 573 ° C. for quartz and cristobalite shows a large expansion at about 200 to 300 ° C.
When the temperature is lower than ℃, the organic binder has the effect, and when the temperature is higher than 200 ℃, the inorganic binder has the effect.

A suitable blending amount of the acrylic resin or vinyl acetate resin-based organic binder is 5 to 15 parts by weight in order to obtain appropriate strength without suppressing expansion from room temperature to 200 ° C. Further, in order to obtain a proper strength without suppressing expansion at 200 ° C. or higher, an appropriate blending amount of the alumina sol or silica sol-based inorganic binder is 1 to less than 10 parts by weight. When the amount of the organic binder is less than 5 parts by weight and the amount of the inorganic binder is less than 1 part by weight, insufficient strength causes casting defects such as casting burrs and adversely affects compatibility. If the organic binder is 20 parts by weight or more and the inorganic binder is 18 parts by weight or more, the strength is too large, the cushioning property is lost, the expansion of the mold is suppressed, and the compatibility with the abutment part of the cast body becomes poor. The reason for adding the inorganic powder typified by alumina powder is to give the feel of asbestos paper, and 10 to 40 parts by weight is suitable.

As the inorganic fibers having a heat resistance of 1000 ° C. or higher according to the present invention, in addition to ceramic fibers having a weight ratio of Al ₂ O ₃ / SiO ₂ of 0.4 to 0.6, alumina fibers and zirconia fibers are usually used. , Shirasu fiber, potassium titanate fiber can be used, and the suitable compounding amount is 30 to 60 parts by weight. Further, a suitable blending amount of glass fiber is 10 to 50 parts by weight. Further, the mixing of the conventionally used natural pulp also improves the workability of papermaking.

Furthermore, in order to control the water absorption of the ring lining material, the modified silicone resin is added to a part of the organic binder to improve the reproducibility of the expansion of the cast body, and the compatibility with the abutment is favorable. Got

Further, there are the beater size method and the impregnation method as the method of attaching the binder, both of which have the same effect as the ring lining material, but the former is more preferable in terms of the workability of mounting on the casting ring. Was excellent. That is, when the binder was adhered by the beater size method, resin migration did not occur and the ring-lined paper was finished flexibly, so there was no breakage when mounting on the ring, and smooth mounting was possible.

[0021]

The present invention will be described in detail with reference to the following examples. Examples 1 to 35 35 parts by weight of ceramic fiber (Nippon Steel Chemical SC-1260R),
Disintegrate 25 parts by weight of aluminum powder, 25 parts by weight of glass fiber, and 15 parts by weight of kraft pulp (NBXP) in water. 2.5 parts by weight of silica sol (solid content), acrylic resin (Toa Gosei P
DLA-160WR) 5 to 15 parts by weight (solid content), 1 part by weight of modified silicone emulsion (active ingredient), polymer coagulant, papermaking by the usual method, drying and 0.7 mm sheet Obtained. (Made by GC, product name New Casting Liner)

Examples 4 to 6 50 parts by weight of ceramic fiber, 25 parts by weight of alumina powder, and 25 parts by weight of glass fiber are disintegrated in water. Add 1 to 10 parts by weight of alumina sol (solid content), 10 parts by weight of vinyl acetate resin, 1 part by weight of modified silicone emulsion (active ingredient), and further add a polymer flocculant. Got a sheet of. (Made by GC, product name New Casting Liner)

The tensile strength of the ring lining material was measured by cutting a 0.7 mm thick sheet into a length of 50 mm and a width of 25 mm, heating at room temperature and 700 ° C., then cooling to room temperature and using a tensile tester. In the cast burr generation test, a ready-made crown type wax pattern was planted in a truncated cone, a casting ring lined with a ring lining material was fixed to the truncated cone, the pattern was embedded in the mold material, and then heated and burned at 700 ° C. A dental gold-silver-palladium alloy (trade name: Castwell MC12: manufactured by Jitsu Dental Industry Co., Ltd.) was cast, cooled to room temperature, taken out of the mold, and visually checked for burrs. The mold material is 70% by weight of Chris barite powder with an average particle size of 10 μm and α hemihydrate gypsum 30 with an average particle size of 15 μm.
A mixture was prepared by mixing the weight% at a water mixing ratio of 0.33 and used.

The compatibility is A. D. A wax pattern is prepared by a method of dental technique using the full crown type and MOD inlay type in A standard No. 2, cast in the same manner as in the casting burr generation test, and the cast body is taken out of the mold and then returned to the original shape. Good and poor compatibility was observed depending on the degree of the gap with the prototype.

[0025]

[Table 1]

[0026]

As is apparent from Table 1, the ring lining material using both the inorganic binder and the organic binder does not contain asbestos, but has appropriate flexibility, cushioning action and strength at room temperature and at the time of heating. In addition, a casting defect such as a casting burr does not occur in the cast body, and the compatibility of the cast restoration with the defective abutment portion is also good. It was found that the performance required for the ring lining material for automobiles has been improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sei Miyashita 630 Tarui-cho, Fuwa-gun, Gifu Prefecture, Japan Inorganic Stock Company Tarui factory

Claims (3)

[Claims] 1. A dentistry characterized by comprising inorganic fiber, glass fiber, and inorganic powder having heat resistance of 1000 ° C. or more as main components, binding them with an inorganic binder and an organic binder, and molding into a sheet. Ring lining material for casting. 2. The inorganic binder is alumina sol and / or
Alternatively, the ring lining material for dental casting according to claim 1, wherein the silica sol and the organic binder are composed of a synthetic resin emulsion and a modified silicone resin emulsion. 3. A mixture of inorganic fiber, glass fiber and inorganic powder having heat resistance of 1000 ° C. or higher as main components, disintegrated and mixed in water, mixed with an inorganic binder and an organic binder to obtain a predetermined thickness. 1. A method for producing a ring lining material for dental casting, comprising forming into a sheet by papermaking, dehydration, drying.