JPH06169932A - Ceramic crown manufacturing method - Google Patents

Abstract

(57) [Summary] [Structure] After taking an impression of an abutment tooth or cavity, a model is prepared from the impression, and then a curable ceramic paste is built up and cured on the model, and then the cured body is removed from the model,
A method for producing a ceramic dental crown, which comprises firing the cured body. [Effect] It is possible to fabricate a ceramic crown or inlay by a simple operation without the need for producing a double impression and a double model as in the conventional case. Moreover, the impression is taken only once, so it has excellent dimensional stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a ceramic crown.

[0002]

2. Description of the Related Art Materials used for the restoration of teeth which have been lost due to caries or the like, that is, the restoration of crowns, are roughly classified into three types called composite resins called inorganic and organic composite materials, metals and ceramics. Above all, ceramics are highly evaluated as restoration materials because of their excellent durability and aesthetics.

As the ceramics for dental crowns, there is used a material called a metal-baked porcelain in which a cast body of a metal, which is advantageous in strength, is used as a base and ceramics are baked on the surface thereof.
There is a material called all-ceramics in which all parts are made of ceramics.

The market for all-ceramics has been expanding in recent years. This is partly due to the fact that the strength, which has been a defect until now, is gradually improving, but the other major reason is the excellent aesthetics of all ceramics.

[0005] Crown ceramics are generally relatively expensive and require a high level of physical properties. Of these, aesthetics are especially important, and great efforts are being made by dental technicians to obtain the same appearance as natural teeth. Comparing this aesthetics with metal-baked porcelain and all-ceramics, the latter is overwhelmingly superior. This is because all-ceramics are generally semi-transparent materials that transmit light as well as natural teeth, whereas metal-baked porcelain does not transmit light because it has a metal layer inside it This is because the transparent feeling of can not be reproduced.

As described above, although it is an all-ceramics for dental crown which basically has excellent properties, on the other hand, the manufacturing process thereof is complicated and a great deal of labor is required for manufacturing. That is, the general manufacturing method of all-ceramics for dental crowns is as follows. First, the impression material is used to obtain an impression of an abutment or a cavity. Next, plaster is poured into the impression to form a tooth profile called a model. Furthermore, the impression of this gypsum model is taken to make a multiple impression. A refractory model material is poured into this complex impression to prepare a complex model (also called a refractory model). After that, a paste prepared by mixing ceramic powder and water is built up on the multiple model to reproduce the crown morphology. After putting the ceramics built on this model into the furnace and firing,
The composite model is removed to obtain a ceramic fired body.

As described above, the operation of taking an impression and the operation of making a model, which should originally be done only once, must be performed twice, respectively.
The production of multiple models makes the work process more complicated. This is because the gypsum model is decomposed by firing and cannot retain its shape, and a refractory model is required. The production of the compound model also complicates the subsequent operation. In other words, the composite model needs to be fired before the paste consisting of the ceramic powder and water is built up on it, and since the composited model that has been fired is porous, it easily absorbs water, which makes the building operation difficult. It is also necessary to immerse the fired composite model in water for a certain period of time. In addition, there is a problem that accuracy is easily deteriorated in terms of dimensions due to taking impressions twice.

[0008]

SUMMARY OF THE INVENTION As described above, there is a demand for a method for producing a ceramic for crowns which takes a double impression and does not require the production of a double model.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to overcome the above technical problems. As a result, they have found that it is possible to manufacture crown ceramics that do not require multiple impressions by using a curable ceramics paste for building up, and have completed the present invention.

That is, according to the present invention, after taking an impression of an abutment tooth or a cavity, a model is prepared from the impression, then a curable ceramic paste is built up on the model, and after curing, the cured body is removed from the model, The present invention relates to a method for producing a ceramic crown, which comprises firing the cured body.

The impression material used for obtaining the impression of the abutment tooth or cavity is not particularly limited, and a known material can be used.
For example, the most common is an agar-alginate combined impression material, but in addition, a condensation-type or addition-type silicone-based impression material, a polyether-based impression material, or the like can also be used.

As a method of obtaining an impression using the impression material, a usual method can be adopted. That is, in the agar-alginate combined impression, after uniformly mixing the alginate impression material and water, the mixture was poured into a tray and separately heated, and the agar having a low viscosity was poured into the details of the target abutment tooth or cavity. The tray is placed in the oral cavity, and after about 3 minutes, the agar and the impression material are cured and then removed. The basic operation is the same in the case of silicone type and polyether type, and an impression material having a desired viscosity is poured into the abutment tooth or cavity and the tray, the tray is mounted in the oral cavity, and taken out after curing.

Known materials can be used for the model used in the present invention. Materials used for this model, that is, model materials, are roughly classified into ceramics, metals, and resins. Among them, ceramics are most commonly used. The types of ceramic-based model materials include gypsum-based, refractory-based, cement-based, etc., but gypsum-based is most often used in terms of overall performance such as accuracy including cost and operability.

A known method is used for using the model material. Taking a gypsum system as an example, a gypsum model can be obtained by uniformly mixing gypsum and water in a powder-liquid ratio specified by the manufacturer, pouring the mixture into an impression, and leaving it for about 1 hour.

The curable ceramics paste used in the present invention means a paste-like material which can be easily cured during a technical operation and becomes a ceramics sintered body by firing the cured body. For example, the paste can be obtained by mixing an ordinary dental porcelain powder with a curable kneading liquid.

The curable kneading liquid usually comprises a monomer having a (meth) acrylic group, an organic solvent and a polymerization initiator.

Specific examples of the monomer having a (meth) acryl group include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate and dipentaerythritol tetra. Examples thereof include (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

As the above organic solvent, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, decalin, benzyloxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol,
Butyl phenyl ether, phenetol, pentyl phenyl ether, methoxytoluene, benzyl ethyl ether, cineol, dimethyl benzoate, diethyl benzoate, ethyl cinnamate, dimethyl phthalate, diethyl phthalate and the like can be specifically mentioned. Those having a low vapor pressure and a low unpleasant odor are preferable.

Curing of the curable ceramics paste of the present invention is achieved by photopolymerization, thermal polymerization, room temperature chemical polymerization by mixing two chemical species, or a combination thereof, each of which uses the following initiators. These initiators are generally present in the curable kneading liquid,
As will be described later, the components may be present separately in the two packaging pastes.

As the photopolymerization initiator, a combination of a photosensitizer and a photopolymerization accelerator is suitable. Examples of such photosensitizers include benzoin, benzoin methyl ether, benzoin ethyl ether, camphorquinone, benzyl, α
Examples include naphthyl, acetonaphthene, 2,4-diethylthioxanthone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Photopolymerization accelerators include N, N-dimethyl-p-toluidine, N, N-diethyl-p-toluidine, p-dimethylaminobenzaldehyde, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid. Amino ester, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, 5-butyl barbituric acid, 1-benzyl-5-phenyl barbituric acid and the like are preferably used.

Benzoyl peroxide, cumyl peroxyneodecanoate, azobisisobutyronitrile and the like are preferably used as the thermal polymerization initiator.

The room-temperature chemical polymerization initiator is composed of a radical generator and an accelerator. By mixing the two at the time of use, curing occurs after a certain period of time. Examples of the radical generator include benzoyl peroxide and lauroyl peroxide, and examples of the accelerator include dimethylaniline and dimethylparatoluidine.

The dental porcelain powder used in the curable ceramics paste of the present invention is not particularly limited, and known powders can be used. A typical composition is SiO ₂ 40-
_{70wt%, Al 2 O 3 10~20wt} %, K 2 O5~1
_{4wt%, Na 2 O1~11wt%,} BaO0~6wt
%, CaO 0 to ₃ wt%, MgO 0 to 1 wt%, B ₂ O ₃
0 to 12 wt% and TiO _{2 0 to} 10 wt%. Those having an average particle diameter of 30 to 60 μm are preferably used.

In order to facilitate the prediction of the color tone after firing, the kneaded product preferably has transparency. For this reason, the difference in the refractive index between the kneaded liquid and the porcelain powder is preferably within 0.04. .

As an example of the packaging form of the curable ceramics paste of the present invention, a powder-liquid type in which the aforementioned porcelain powder and a curable kneading liquid are separately prepared and mixed at the time of use to form a paste, Examples thereof include a one-paste type in which both are mixed in advance to be in a paste state, or a two-paste type in which the mixed paste is divided into two.

In the case of photopolymerization or thermal polymerization, all the components can be packaged in the same package, so that the one-paste type is preferably used. In the case of normal temperature chemical polymerization, a powder-liquid type or a two-paste type is generally used in which a radical generator is added to either one and an accelerator is added to the other.

The method of building the curable ceramic paste is not particularly limited, and a method used for building ordinary dental porcelain or hard dental resin can be used. Specifically, if necessary, the powder and the kneading liquid or two kinds of pastes are kneaded to obtain a uniform paste, and then the paste is built up on a model. At this time, in order to assist the build-up, it is possible to perform an operation called condensate to absorb the liquid while applying vibration to the model. After being built up, it is cured by light irradiation, heating, etc. to maintain its shape.

Since the cured product obtained by the above method is not easily deformed, it can be removed from the model and fired. Therefore, a dental crown can be manufactured without the need for making a double impression and a double model, and the working process is greatly simplified.

When the crown to be manufactured has a large size like a bridge extending over a large number of teeth and the hardened body is easily deformed, a simple model material (Lamina Retouch Best / Matsufu Co., Instant Refractory / Generic Pentron Co., Ltd. Manufactured). Since these simple model materials can be directly baked after fixing the cured body, there is no need for troublesome operations such as making a multiple impression and immersing the multiple models in water.

When the built-up body is removed from the model, it may be difficult to separate it. In such a case, it is preferable to apply a separating material to the model in advance. For example, when the model is gypsum, a commercially available gypsum separating material may be used.

The method for firing the cured product is not particularly limited. As a typical method, the cured product is fired at the entrance of a porcelain firing furnace kept at 600 ° C. for 3 to 10 minutes, and then in the firing furnace for 5 to 20 minutes. Then, by firing according to a firing program specified by the porcelain manufacturer, a desired ceramic crown can be obtained.

In the crown ceramics, a more aesthetic crown can be obtained by forming a natural tooth-like multi-layer structure in the interior, but the method of the present invention facilitates such multi-layer structure. Can be made. That is, the ceramic crown obtained by the above manufacturing method is used as a core, and in order to prevent the core from being deformed by heat, enamel porcelain having a firing temperature lower than that of the core by 200 ° C. or more is formed on the surface and then fired. According to this method, it is possible to obtain a ceramic crown having a multi-layer structure with good compatibility without using an investment material.

[0033]

EFFECTS OF THE INVENTION It is possible to manufacture a ceramic crown or inlay by a simple operation without the need for preparing a double impression and a double model as in the prior art. Moreover, the impression is taken only once, so it has excellent dimensional stability.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Dental agar (Dentroid Brown, manufactured by Dentronics) immersed in boiling water for 10 minutes was kept at a constant temperature of 60 ° C. An alginate impression material (Tokuso New A-1, manufactured by Tokuyama Soda Co., Ltd.) was kneaded with water and poured into a tray. Agar of 60 ° C. was poured onto the central incisors of the upper jaw of a healthy person, and the tray was pressed, and after 3 minutes, the tray was taken out to obtain a full-jaw impression. Dental anhydrite (TOX sauce tone 1, manufactured by Tokuyama Soda Co., Ltd.) was kneaded with water, poured into the above-mentioned full-jaw impression, allowed to stand for 1 hour, and then the plaster model was taken out. The surface of the left central incisor of this model was scraped off to prepare a simulated abutment tooth.

Tetrafunctional acrylic monomer, A-TMMT
(Shin Nakamura Chemical Co., Ltd.) 30 parts by weight, dimethyl phthalate (Wako Pure Chemical Industries, Ltd.) 25 parts by weight, diethylene glycol monomethyl ether 45 parts by weight, 2,4-diethylthioxanthone 0.10 parts by weight, p-dimethylaminobenzoic acid Ethyl 0.5
Parts by weight were mixed in the dark. This mixed solution was mixed with porcelain powder (VMK68, manufactured by Vita) and then built up while condensing on the simulated abutment tooth. Using a dental light irradiator (white light, manufactured by Takara Belmont Co., Ltd.), the built-up body was irradiated with light for 30 seconds to obtain a cured body. After removing this cured product from the plaster model, a simple investment material (instant refractory, made by Generic Pentron Co., Ltd.) was filled inside the cured product, and the porcelain furnace (made by Towa Giken Co., Ltd.) was kept at 600 ° C. After 10 minutes of drying, the product was baked in a furnace for 10 minutes, and then vacuum baked while raising the temperature to 960 ° C at 42 ° C / min.

As a result of mounting the ceramic crown taken out from the furnace on the simulated abutment tooth, the compatibility was equal to that of the all ceramic crown by the conventional method.

Further, after the low melting porcelain (Dussela-LFC, manufactured by Dussella) is built on the surface of the crown, it is 660 ° C.
Then, it was fired to obtain a ceramic crown having a multilayer structure. The color tone, transparency, and compatibility of this crown were the same as those of the conventional all-ceramic crown.

Claims (1)

[Claims] 1. An impression of an abutment tooth or a cavity is taken, a model is produced from the impression, a curable ceramics paste is then built up on the model, and after curing, the cured body is removed from the model, and the cured body is obtained. A method for manufacturing a ceramic dental crown, which comprises firing.