JPH10205A - Manufacture of dental mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a precisely shaped dental mold corresponding to a wax pattern almost free from influence of the hardening expansion of an investment material. SOLUTION: A powdery phosphate based investment material 50g is ground for one minutes at room temperature with a special liquid 5cc and water 5cc, and filled in a casting ring in which a wax pattern supported on a truncated conetable is arranged inside. Then, after being left for three minutes at room temperature and hardened initially, the casting ring is thrown in a heating container and heated at 110 deg.C for five minutes. The casting ring taken out of the heating container is heated for twenty minuets by a ring furnace heated at 750 deg.C, with the truncated conetable detached from the investment material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a dental mold used for producing dental castings such as metal floors, inlays, crowns, bridges and the like.

[0002]

2. Description of the Related Art Dental castings such as metal floors, inlays, crowns and bridges are usually manufactured by a lost wax precision casting method using a dental mold.

[0003] When manufacturing a dental mold used in the lost wax precision casting method, first, a duplicate model of a patient's jaw is manufactured, and a wax pattern of a required casting is placed on the duplicate model. To be manufactured. The manufactured wax pattern is placed in a casting ring which is a cylindrical container while being supported on a truncated cone, and the casting ring is filled with a flowable investment material (mold material). You. The investment material is filled into the casting ring until the wax pattern is buried in the investment material together with the truncated cone. The investment material is usually brought into a predetermined fluid state by kneading a phosphate-based or gypsum-based powdery composition with a dedicated liquid or water.

The investment material filled in the casting ring is hardened at room temperature. When the investment material is in a hardened state, the casting ring is put into a heating furnace such as an electric furnace (ring furnace) and is fired by being heated at a predetermined high temperature for a predetermined time. This allows
The wax pattern buried in the investment material is burned, and the investment material is baked to be in a hardened state. As a result, a dental mold in which a cavity having a predetermined shape corresponding to the shape of the wax pattern is formed in the heated investment material.

When a dental casting is manufactured using the dental mold manufactured as described above, the cavity is filled with a molten metal. When the filled molten metal hardens, the mold constituted by the investment material is broken, and the hardened molten metal dental casting is removed.

[0006]

When the investment material filled in the casting ring is fired by heating with a heating furnace,
In order to obtain faithful reproducibility for wax patterns,
Fluctuations in the expansion rate of the investment material must be controlled, and for this purpose the heating temperature and heating time must be strictly controlled.

For example, when a phosphoric acid-based investment material composed of monoammonium phosphate and magnesia clinker is used, the powdery investment material is kneaded with a colloidal silica liquid to obtain a predetermined fluidity. Once filled in the casting ring, the investment material is cured at room temperature for about 60 minutes and is allowed to cure and expand. And
After the investment material hardens and expands, the casting ring is put into a heating furnace and gradually heated to 800 ° C. over a period of about 180 minutes, so that the investment material is fired. Therefore, it takes about 240 minutes from filling of the investment material into the casting ring to completion of the mold.

When a gypsum-based investment material is used, although the time from filling of the investment material to the production of a mold is slightly reduced, the investment material is the same as the phosphate-based investment material. Is cured at room temperature and expanded, and then fired. From the filling of the investment material to the end of firing, 1
It takes about 80 minutes.

In addition, in the case of a phosphate-based or gypsum-based investment material, even if the heating temperature and the heating time are strictly controlled when firing the investment material, the volume change of the investment material is strictly controlled. Burr on the casting surface of the resulting mold
There is a problem that surface roughness, deformation, and the like occur, and reproducibility is not constant.

[0010] Further, in the case of both phosphate-based and gypsum-based investment materials, after they are filled in the casting ring, they are hardened and expanded at room temperature for about 30 minutes. Due to the wax pattern buried in the material, the curing and expansion of the investment material is suppressed, and the casting surface of the investment material may be roughened or may be hardened in a state deformed with respect to the wax pattern.

In a phosphoric acid-based investment material, a powdery investment material composition is usually kneaded with a liquid dedicated to colloidal silica and water in order to obtain a predetermined fluidity. If ammonium monophosphate and magnesia clinker do not sufficiently react with water, there is a problem that the casting surface of the manufactured mold becomes rough.

In addition, in the case of a gypsum-based investment material, when about 30 minutes have passed after filling in the casting ring, the coefficient of hardening expansion has changed greatly, and the timing (time) of charging the material into the heating furnace has been reduced. If it is deviated, there is a problem that the amount of expansion of the investment material at the start of heating is not constant, and cracks and deformation may occur during firing.

Japanese Patent Publication No. 8-2771 discloses a rapid heating type investment material composition to which tridymite is added. This investment material composition is filled into a casting ring in a kneaded state, and after being cured at room temperature for about 30 minutes for curing and expansion, gypsum (cristobalite)
At a heating temperature of about 700 ° C. for a system investment, and at a heating temperature of about 800 ° C. for a phosphoric acid investment,
It is designed to be fired in a heating time of about a minute.

As described above, the investment material can be rapidly heated by using the composition of tridymite having a relatively small coefficient of thermal expansion and not changing the coefficient of thermal expansion abruptly. Rapidly heating to high temperature, 3
The investment material can be fired in a short heating time of about 0 minutes. Therefore, the time from the filling of the investment material to the completion of the firing of the investment material is about 60 minutes, and the manufacturing time of the dental mold is reduced to about 1/3 as compared with the conventional investment material. .

However, even with such a rapid-heating investment material, the investment material must be hardened at room temperature for about 30 minutes in order to harden and expand the investment material after filling the investment material. Therefore, although the firing time can be reduced to about 30 minutes, it takes as long as 60 minutes from filling of the investment material to completion of firing. For this reason, there is a demand for an operator such as a dental technician who manufactures a dental mold to further reduce the working time for manufacturing the mold.

The investment material filled in the casting ring is hardened and expanded at room temperature for about 30 minutes as in the case of the conventional investment material. It is not possible to prevent roughening of the casting surface of the investment material, deformation of the investment material, and the like that occur when the material is hardened and expanded.

The present invention is intended to solve such a problem, and an object of the present invention is to provide a dental pattern in a short time of about 30 minutes after filling an investment material into a container and completing the embedding of a wax pattern. It is to provide a method by which a mold can be manufactured. Another object of the present invention is to produce a dental mold in which the roughening of the casting surface, which is considered to be caused by hardening expansion, and the occurrence of deformation can be suppressed, and the dental mold to be manufactured has excellent dimensional accuracy and reproducibility. It is to provide a method.

[0018]

According to the method for manufacturing a dental mold of the present invention, a wax pattern molded into a predetermined shape is arranged in a container, and the wax pattern is buried in the container so that the wax pattern is buried. And a thermal expansion step of heating so that the investment material filled in the container thermally expands,
A firing step of heating the investment material so as to fire.

The thermal expansion step may be carried out immediately after the investment material is filled in the container, or after a lapse of about 2 to 4 minutes after the investment material is filled in the container. You may make it.

The heating temperature in the thermal expansion step is usually about 70 to 200 ° C., and the heating time is 5 minutes or more. The heating temperature in the firing step is usually 700 ° C. or higher, and the heating time is 15 minutes or longer.

[0021]

Embodiments of the present invention will be described below in detail.

In the method of manufacturing a dental mold of the present invention, a wax pattern of a cast manufactured based on a replica model of a patient's jaw is used in the same manner as a normal lost wax precision casting method.

In the method for manufacturing a dental mold of the present invention, first, the wax pattern is placed together with the truncated cone in the casting ring while the wax pattern is supported on the truncated cone. On the other hand, the powdered investment material composition is kneaded with water or a mixed solution of a dedicated liquid and water to make it suitable fluidity. The investment material composition may be either a phosphate type or a gypsum type, and may be any of a rapid heating type and a conventional type other than the rapid heating type.

When the investment material is made to have a predetermined fluidity, the investment material is filled into a casting ring in which a wax pattern supported by a truncated cone is disposed. The investment material is filled into the casting ring such that the wax pattern supported on the truncated cone is completely buried in the investment material.

When the investment material is filled into the casting ring and the wax pattern is buried, the investment material is heated together with the filling ring at a temperature of 70 to 200 ° C. for 5 minutes or more so that the investment material thermally expands. Is done. When the investment material is heated to such a temperature, the wax pattern embedded in the investment material is in a softened state, and the investment material is in a thermally expanded state.

The heating of the investment material may be carried out immediately after filling, before the investment material filled in the filling ring starts to harden and expand, but it takes about 2 to 4 minutes for the investment material to initially harden. The heating may be performed after elapse of.

When the investment material is heated immediately after the investment material is filled in the casting ring, the investment material is heated until the investment material thermally expands.
It is considered that the investment material is initially cured and the shape corresponding to the wax pattern is maintained. After a lapse of about 2 to 4 minutes from the filling of the investment material, the investment material is in an initial hardened state and maintains a shape corresponding to the wax pattern. In any case, the investment material is heated in a state where the expansion corresponding to the wax pattern is maintained and the curing expansion has not started, and at the time when the investment material starts the thermal expansion, the wax pattern is It becomes a softened state. Therefore, when the investment material starts to thermally expand, it is uniformly thermally expanded throughout without being restricted by the wax pattern embedded in the investment material. Since the investment material has been cured at the same time as the thermal expansion, it is considered that the investment has been cured and expanded, and the cured expansion is considered to be absorbed by the thermal expansion.

The heating temperature of the investment material is set such that the wax pattern is softened when the investment material thermally expands.
Set appropriately. Also, the heating time of the investment material is appropriately set according to the composition of the investment material so that the investment material thermally expands.

The investment material can be heated by a dedicated heater capable of setting the temperature and time and holding the casting ring inside, or by setting the casting ring at a predetermined heating temperature. It is heated using a general-purpose heater that can be held at a temperature of about 0.1 mm.

In the case of a phosphate-based investment material, the heating at this time promotes the reaction between ammonium monophosphate and magnesia clinker and water.

As described above, when the investment material is uniformly thermally expanded by being heated at a temperature of about 70 to 200 ° C. for 5 minutes or more, the truncated cone is removed from the casting ring, and the investment material is fired. Is done. In this case, the investment material is fired, since the investment material is already in a thermally expanded state, it is sufficient to rapidly heat the investment material to a predetermined firing temperature, similarly to the rapid heating type investment material. There is no need to strictly control the heating temperature and the heating time unlike the investment material that is not a rapid type. Then, during this firing, the wax pattern buried in the investment material is incinerated.

The firing temperature of the investment material is slightly higher than the incineration temperature of the wax pattern, and is usually about 850 ° C. for a phosphate investment material and about 750 ° C. for a gypsum (cristobarite) investment material. You. In any of the investment materials, the shortest heating time is about 15 minutes, and is appropriately set to 15 minutes or more in relation to the heating temperature. For firing the investment material, a heating furnace such as an ordinary electric furnace (ring furnace) which has been conventionally used for firing the investment material is used.

When the investment material is fired, the wax pattern buried in the investment material is incinerated and the investment material is in a hardened state. As a result, a dental mold in which a cavity having a shape corresponding to the wax pattern is formed. Therefore, the dental mold is manufactured in a short time within 30 minutes from filling of the investment material into the casting ring to completion of firing.

In the obtained dental mold, a molten metal is injected into a cavity inside thereof, and after the injected molten metal is hardened, the mold constituted by the investment material is destroyed, whereby a metal floor is formed. And a dental casting such as a crown.

The resulting cast dental product has almost no surface roughness and is excellent in compatibility with both gypsum-based and phosphate-based investment materials.

[0036]

【Example】

(Example 1) 50 g of a conventional phosphate-based investment material (trade name "Univest Silky", manufactured by Shofu Co., Ltd.) which is not a powdery high-speed heating type was prepared using 5 cc of a dedicated liquid and 5 cc of water (water temperature 2
3 ° C.) at room temperature of 24 ° C. for 1 minute as usual. On the other hand, a wax pattern of a predetermined shape obtained from a replica model of a patient's jaw was prepared, and placed in a casting ring with the wax pattern supported on a truncated cone. Then, the casting ring was filled with the kneaded investment material. Then, in a room at room temperature 24 ° C.
By leaving it to stand for 3 minutes, it was initially cured at room temperature.

After 3 minutes, the casting ring in which the investment material was initially hardened was put into a heater heated to 110 ° C., and heated at 110 ° C. for 5 minutes. Thereafter, the casting ring is taken out of the heater, the truncated cone is removed from the investment material, and the ring is put into a ring furnace (electric furnace) heated to 750 ° C., and heated at 750 ° C. for 20 minutes. Fired. 2
At the end of the 0 minute heating, the casting ring was removed from the ring furnace. As a result, a dental mold having a cavity having a predetermined shape corresponding to the wax pattern was obtained. In this example, the time required from the filling of the investment material to the completion of the firing was within 28 minutes and 30 minutes.

A 12% gold-palladium alloy in a molten state was injected into the cavity of the obtained dental mold and hardened. When the gold-palladium alloy was in a hardened state, the mold constituted by the hardened investment material was taken out of the casting ring, and the mold was broken to take out the gold-palladium alloy crown.

The obtained crown was in a good condition without surface roughness on the casting surface. When the obtained crown was mounted on the abutment, the inner surface was well fitted and the margin was good.

Comparative Example 1 For comparison, an investment material kneaded with the same materials and conditions as in Example 1 was filled into a casting ring in which a wax pattern supported by a truncated cone was disposed. Then, it was left to cure in a room (room temperature 24 ° C.) for 1 hour. After that, the casting ring filled with the investment material is charged into the ring furnace at room temperature, and the temperature is raised stepwise at a rate of 50 ° C. per minute, and the temperature is raised to about 300 ° C. The temperature was maintained and heated for 30 minutes. 30 for 30 minutes
When the heating at 0 ° C. is completed, heating is performed while increasing the temperature stepwise at a rate of 50 ° C. per minute.
Heat was maintained at that temperature for 0 minutes. As a result, a crown which was a dental mold was obtained. In this comparative example, the time from the filling of the investment material to the end of the heating (incineration) required 120 minutes or more.

When a crown of 12% gold-palladium alloy was cast using the dental mold thus obtained, the cast surface was extremely rough. Further, when the cast crown was mounted on the abutment tooth, the inner surface was tight, and the margin was increased due to the deformation, and the fitting was not good.

Example 2 50 g of a conventional powdery cristobalite investment material (trade name "PDR cristobalite investment material", manufactured by P.D.R. Co., Ltd.) which is not a high-speed heating type was charged with 17.5 cc of water (Water temperature 23 ° C.) and 0.025% dilute sulfuric acid as a hardening accelerator at 25 ° C.
In the room for 15 seconds. On the other hand, a casting ring in which a wax pattern supported by a truncated cone was disposed was prepared, and the kneaded investment material was filled in the casting ring. Immediately after the investment material is filled in the casting ring, the casting ring is charged into a heater heated to 110 ° C.
Heated at a temperature of ° C for 5 minutes. Thereafter, the casting ring was taken out of the heater, the truncated cone was removed from the investment material, and the cast ring was put into a ring furnace heated to 750 ° C., and heated at that temperature for 20 minutes to be fired. When the heating for 20 minutes was completed, the casting ring was removed from the ring furnace. As a result, a dental mold having a cavity having a predetermined shape corresponding to the wax pattern was obtained. In this example, the time from the filling of the investment material to the completion of the firing was within 25 minutes and 30 minutes.

A 12% gold-palladium alloy in a molten state was injected into the cavity of the obtained dental mold, cured, and the mold was taken out by breaking. As a result, a crown as a dental casting was obtained.

The obtained crown was in a good condition without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

(Comparative Example 2) For the purpose of comparison, the investment material used in Example 2 was filled in a casting ring in the same manner as in Example 2 and left indoors (room temperature 25 ° C) for 1 hour. Allowed to cure. After that, the casting ring filled with the investment material is put into the ring furnace at room temperature, and heated while the temperature is gradually increased at a rate of 50 ° C. per minute,
When the temperature reached about 300 ° C., the temperature was maintained and heated for 30 minutes. When heating at 300 ° C. for 30 minutes was completed, heating was performed while gradually increasing the temperature at a rate of 50 ° C. per minute. When the temperature reached 750 ° C., the temperature was maintained for 30 minutes and heated. Therefore, in this comparative example, from the filling of the investment material to the completion of firing, 1
It took more than 20 minutes.

When a crown of 12% gold-palladium alloy was cast using the dental mold thus obtained, the surface roughness of the cast surface was good. However, when the cast crown was mounted on the abutment teeth, the inner surface was tight, and the deformation tended to increase the margin.

(Example 3) 100 g of a conventional powdery phosphate-based investment material (trade name "Cerabest G", manufactured by GC Corporation) which is not a high-speed heating type was prepared using 12 cc of a dedicated liquid and 12 cc of water. After kneading, the wax pattern was filled into a casting ring housed therein. Immediately after the filling of the investing agent was completed, it was charged into a heater heated to 100 ° C. and heated for 5 minutes. Thereafter, the casting ring was taken out of the heater, the truncated cone was removed from the investment material, and then put into a ring furnace heated to 850 ° C., and baked by heating for 15 minutes. In this example, the time from the filling of the investment material to the completion of the firing was within 20 minutes and 30 minutes.

Into the cavity of the obtained dental mold, a gold alloy for baking white porcelain (trade name “Harabond II”, sold by Panaherus Dental Co., Ltd.) is injected in a molten state and hardened, and the dental casting is performed. The crown was obtained as a product.

The obtained crown was in a good condition without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

Example 4 In Example 3, the heating temperature of the investment material filled in the casting ring was 125 ° C. Otherwise, a dental mold was manufactured under the same conditions as in Example 3, and a crown was manufactured using the same mold as in Example 3. The obtained crown was in a good state without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

Example 5 In Example 3, the heating temperature of the investment material filled in the casting ring was 160 ° C. Otherwise, a dental mold was manufactured under the same conditions as in Example 3, and a crown was manufactured using the same mold as in Example 3. The obtained crown was in a good state without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

(Example 6) In Example 3, the heating temperature of the investment material filled in the casting ring was set to 180 ° C. Otherwise, a dental mold was manufactured under the same conditions as in Example 3, and a crown was manufactured using the same mold as in Example 3. The obtained crown was in a good state without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

(Example 7) In Example 3, the investment temperature of the investment material filled in the casting ring was set to 125 ° C.
After heating for 5 minutes, at a temperature of 850 ° C. for 20 minutes
Bake by heating for minutes. Otherwise, a dental mold was manufactured under the same conditions as in Example 3, and a crown was manufactured using the same mold as in Example 3. The obtained crown was in a good state without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

(Example 8) In Example 7, the heating temperature for firing the investment material filled in the casting ring was set to 80.
At 0 ° C., the heating time was 25 minutes. Otherwise, Example 7
A dental mold was manufactured under the same conditions as in the above, and a crown was manufactured using the same mold as in Example 7. The obtained crown was in a good state without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

Example 9 100 g of a powdery phosphate-based investment material of rapid heating type (trade name "Cerabest Quick", manufactured by GC Co., Ltd.) was added to 11 cc of a dedicated liquid and
The mixture was kneaded with cc of water and filled into a casting ring containing a wax pattern. Immediately after the filling of the investing agent was completed, it was charged into a heater heated to 110 ° C. and heated for 7 minutes. Thereafter, the casting ring was taken out of the heater, the truncated cone was removed from the investment material, and the cast ring was put into a ring furnace heated to 750 ° C., and heated for 20 minutes to be fired. In this example, the time from the filling of the investment material to the completion of the firing was within 27 minutes and 30 minutes.

A 12% palladium alloy was poured into the cavity of the obtained dental mold in a molten state and hardened to obtain a crown as a dental casting.

The obtained crown was in a good condition without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

Example 10 A conventional powdery phosphate-based investment material that is not a rapid heating type (trade name "Lapis Mold-
G ", 100 g of Towa Giken Co., Ltd.) was kneaded with 8 cc of a dedicated liquid and 15 cc of water, and filled in a casting ring containing a wax pattern therein. After 3 minutes had passed since the filling of the investing agent was completed, it was charged into a heater heated to 110 ° C. and heated for 5 minutes. Thereafter, the casting ring was taken out of the heater, the truncated cone was removed from the investment material, and the cast ring was put into a ring furnace heated to 850 ° C., and heated for 20 minutes to be fired. In this example, the time from the filling of the investment material to the completion of the firing was within 25 minutes and 30 minutes.

In the cavity of the obtained dental mold, a gold alloy (trade name “UNOREX”, sold by Harmans Co., Ltd.)
Was injected in a molten state and hardened to obtain a crown as a dental casting.

The obtained crown was in a good condition without surface roughness on the casting surface. When the crown was mounted on the abutment, both the inner surface and the margin were good, and a good fit was obtained.

[0061]

As described above, the method for manufacturing a dental mold according to the present invention is such that after the investment material is filled in the container in which the wax pattern is arranged, the investment material is once heated so as to thermally expand, and thereafter, is heated. Since the investment material is configured to be fired, the time required for hardening and expanding the investment material filled in the container is not required, and the casting surface is roughened and deformed due to the expansion. Are also prevented. Furthermore, since the investment material to be fired has already been heated and expanded, it is not necessary to strictly control the heating temperature and the heating time for firing, and it is possible to heat the material rapidly. As a result, a dental casting can be obtained in a short time of 30 minutes or less. Therefore, the dental mold manufactured by the manufacturing method of the present invention can manufacture a dental casting having excellent adaptability with almost no casting surface roughness.

Claims (5)

[Claims] 1. A step of placing a wax pattern molded into a predetermined shape in a container and filling an investment material in the container so that the wax pattern is buried, wherein the investment material filled in the container is A method for producing a dental mold, comprising: a thermal expansion step of heating so as to thermally expand; and a firing step of heating so that the thermally expanded investment material is fired. 2. The method for producing a dental mold according to claim 1, wherein the thermal expansion step is performed immediately after the investment material is filled in the container. 3. After the investment material is filled in the container,
The method for producing a dental mold according to claim 1, wherein the thermal expansion step is performed after about 4 minutes have elapsed. 4. The heating temperature in the thermal expansion step is 70.
The method for producing a dental mold according to claim 1, wherein the heating temperature is about 200 ° C. and the heating time is 5 minutes or more. 5. The heating temperature in the firing step is 700.
The method for producing a dental mold according to claim 1, wherein the heating temperature is not less than 15 ° C and the heating time is not less than 15 minutes.