JPS62164453A - Method for forming denture bed - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a denture base by compression molding of a thermoplastic resin.

<Prior Art> The present inventors have previously developed a method for manufacturing a denture base by compression molding a thermoplastic resin, and have filed a patent application (Japanese Patent Laid-Open No. 58-14F39).

The method is to place a thermoplastic resin material on top of the plaster mold in the lower flask and heat it to soften it, then place the plaster mold in the upper flask containing the artificial tooth on top of it and perform compression molding to create the denture base. This is the way to do it.

However, in some cases, the filling property of the resin may not be sufficient, or sink marks, voids, etc. may occur.

<Problems to be Solved by the Invention> The purpose of the present invention is to provide a method that improves the above drawbacks and provides stable and good results, that is, a good @fungal bed with good filling properties and no sink marks or voids. Our goal is to provide the following.

<Means for Solving the Problem> The present inventors placed a thermoplastic resin material on the plaster mold in the lower flask and softened it by heating, and then placed a plaster mold in the upper flask containing the artificial tooth. In a method of fabricating a denture base by compression molding, the inventors have found that the above problems can be solved by setting the molding speed in the compression molding to a speed range of 0.5 ms per second to 50 mm per second. .

In the present invention, there are no particular limitations on the method of providing a desired denture base-shaped cavity inside the upper and lower flasks. For example, a so-called lost wax method can be applied in which a wax denture made of paraffin is embedded in plaster in upper and lower flasks, heated and softened, and then the paraffin is removed according to a legal method.

The thermoplastic resin used for denture bases in the present invention does not undergo thermal deterioration through the molding method, has an appropriate viscosity, has good formability, and has a color similar to that of the gums. The resin is required to be blue in color, have appropriate rigidity and moisture resistance, and be tough enough not to cause stress cracks during use. Therefore, polystyrene, polymethyl methacrylate, polymethyl pentene-1, transparent nylon, polycarbonate, polyarylate, polyester carbonate, polyethylene terephthalate, transparent ABS, polysulfone resin, etc. are used.
In particular, polysulfone-based resins such as polysulfone and polyethersulfone are preferred because they have excellent moisture resistance, rigidity, stress cracking resistance, and the like.

The polysulfone resin used as a preferred embodiment in the present invention is defined as a polyarylene polyether polysulfone in which arylene units are located in a disordered or ordered manner with ether and sulfone bonds. For example, UCC's polysulfone Udel■ having a structure can be mentioned.

In the present invention, there are no restrictions on the method of heating and softening the thermoplastic resin, but the thermoplastic resin can be softened in the form of powder, granules,
Make it into a plate shape and place it on the plaster model inside the lower flask.
A preferred method is to soften the resin at a temperature of 200 to 400°C using a tail air oven, hot air circulation dryer, infrared heater oven, or the like, depending on the type of resin. A plate-shaped resin molded product is preferably used because it is difficult for air to be trapped between the molded products due to softening.

In the present invention, there are no particular limitations on the compression molding method. For example, a method can be applied in which the upper flask or the lower flask is actuated by hydraulic drive to pressurize and bring the upper and lower flasks into close contact.

It is also possible to apply a method in which the upper or lower flask is brought into pressure contact by driving by an electric motor, driving by pneumatic pressure, or the like.

In the present invention, the molding speed in compression molding refers to the time after the top of the thermoplastic resin heated and softened on the plaster in the lower flask comes into contact with the plaster in the upper flask or the artificial tooth part during the operation process of the upper or lower flask. , means the molding speed in the process until the pressure welding is completed.

The distance from contact to pressure contact varies depending on the size of the denture base to be molded, but is usually in the range of 3 to 20 stages.

The molding speed used is 0.5 to 50 m++++ per second, and preferably 1 to 20 m per second in view of the viscosity increase due to cooling of the softened resin and the escape of the resin onto the flask dividing surface.

If the speed is less than 0.5 m/s, the resin that has been heated and softened will solidify as time passes until molding, and sufficient flow of the resin will not be obtained, resulting in poor filling performance. In this case, a good denture base cannot be stably obtained due to the occurrence of sink marks and voids due to the escape of the heated and softened resin to the flask dividing surface.

Note that the molding speed can be controlled in multiple stages. The movement speed of the upper or lower flask during the operation process up to contact is not particularly limited, but usually
It is preferable to carry out the process quickly in order to prevent an increase in viscosity due to cooling of the resin.

<Effects of the present invention> The present invention has the following effects.

■ It prevents the resin from escaping onto the flask dividing surface, and since sufficient pressure is applied, a good denture base with no sink marks or voids can be stably obtained.

■ Since the resin has sufficient fluidity, there is no problem with filling thin parts due to cooling of the softened resin, and a good denture base can be obtained.

■ Since thermoplastic resin is used, there is no problem with residual monomers, which is a problem with conventional acrylic heating polymerization methods.

<Examples> The present invention will be specifically described below with reference to Examples, but these are merely illustrative of preferred embodiments and are not limited to the scope of the Examples.

Example 1 The wax was heated to soften the wax and form a plaster mold.

Next, a gingiva-colored U of polyether sulfone (ICI% Victrex 4100G) was applied.
Shaped molded product (U-shaped with a size equivalent to the alveolar ridge)
was placed on the plaster mold in the lower flask and heated to 850°C.
The molded article was softened by blowing hot air.

The speed at which the plaster in the upper flask and the resin on the plaster in the lower flask come into contact is 100 m+n per second, as shown in
Compression molding was then carried out at a molding speed of 5 g per second during a stroke of about 10 mm until the flask was pressed, and after the completion of the pressing, the mixture was allowed to cool naturally.

After cooling, the upper and lower flasks were separated and the denture base was taken out.

Comparative Example 1 A denture base was produced in the same manner as in Example 1, except that the molding speed was 100 mm/sec.

Comparative Example 2 A denture base was produced in the same manner as in Example 1 except that the molding speed was 0.2 m/sec.

The results are shown in Table 1. In Comparative Examples 1 and 2, sink marks, voids,
In contrast, poor filling and thickening of the ridge portion were observed, whereas in Example 1, a good denture base was obtained.

Table 1 Comparison of molding results

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which the upper and lower flasks are attached to a compression molding apparatus. FIG. 2 is a diagram showing a state in which the gypsum in the upper flask and the resin on the gypsum in the lower flask are in contact. ■・・・Top flask■・・・Artificial tooth■・・・Gypsum mold■・・・Thermoplastic resin■・・・Gypsum model■・・・... Gypsum type ■ ... Lower flask

Claims (1)

[Claims] In a method of fabricating a denture base by placing a thermoplastic resin material on a plaster mold in a lower flask, heating and softening it, and then placing a plaster mold in an upper flask containing an artificial tooth thereon, by compression molding. A denture base manufacturing method, characterized in that the compression molding is performed at a molding speed in the range of 0.5 mm per second to 50 mm per second.