JPH0250740B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a denture base by compression molding of thermoplastic resin. The present inventors previously developed a method for manufacturing a denture base by compression molding a thermoplastic resin and filed a patent application (Japanese Patent Application Laid-Open No. 1439/1983). 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. As a result of research, the present inventors found that in the above compression molding method, like the compression molding that is usually performed,
If no treatment is performed on the artificial teeth built into the upper and lower flasks, the fusion between the artificial teeth and the resin forming the denture base will not be sufficient.
It has been found that artificial teeth have the disadvantage of being easy to detach from the denture base. The object of the present invention is to provide a method that improves the above-mentioned drawbacks and provides good results, ie, a denture base in which the artificial tooth is firmly implanted and has good filling properties. The feature of the present invention is that a thermoplastic resin material is placed on top of the plaster mold in the lower flask, heated and softened, and then the plaster mold in the upper flask containing the artificial tooth is placed on top and compression molded. In the method of manufacturing a denture base, the root of the artificial tooth is preheated to 80 to 300°C and then compression molded. 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. It is required that the resin be colorable, have appropriate rigidity and moisture resistance, and be tough enough not to cause stress cracks during use. Therefore, polystyrene, polymethyl methacrylate, polymethylpentene-1, transparent nylon, polycarbonate, polyarylate, polyester carbonate, polyethylene terephthalate, transparent ABS, polysulfone resins, etc. are used, but in particular polysulfone, polyethersulfone Polysulfone resins such as Polysulfone resins are preferred because they have excellent moisture resistance, rigidity, and stress cracking resistance. 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 polysulfone Udel with the structure

One example is polyether sulfone Victrex manufactured by ICI, which has the structure of [Formula]. Examples of the artificial teeth used in the present invention include resin teeth made of acrylic resin, porcelain teeth, polycarbonate teeth, polyarylate teeth, polysulfone teeth, etc., which are commonly used as artificial teeth in the past. As a material for artificial teeth, it is a resin that can be colored to approximate natural color, has appropriate rigidity, wear resistance, and moisture resistance, and is tough enough to prevent stress cracks during use. something is required. Therefore, in addition to the above-mentioned artificial teeth, artificial teeth made of polystyrene, polymethylpentene-1, polyamide, polyester carbonate, polyethylene terephthalate, transparent ABS, polyether sulfone, etc., and compositions containing these resins and appropriate reinforcing agents can be used. artificial teeth can be used. It is preferable to use an artificial tooth made of a material having the same or similar structure or properties as the thermoplastic resin for denture bases, since the adhesion between the artificial teeth and the denture base is better. The method of incorporating the artificial tooth into the plaster mold in the upper flask is not particularly limited. A commonly used method is to place a wax denture base model with artificial teeth in it in a flask, pour in plaster, and let it harden. After the gypsum hardens, a method is applied in which the wax is heated and softened by passing through a method, and then drained. Any method can be used to preheat the root of the artificial tooth built into the flask, such as heating only a predetermined part of the artificial tooth locally with hot air or infrared rays, or heating with a burner. be. If only the part to be implanted into the denture base, that is, the root of the artificial tooth, is heated to a state close to softening, and the tip of the artificial tooth is compression molded without changing its shape, the relationship between the artificial tooth and the denture base will be better. In order to obtain a good denture (a combination of an artificial tooth and a denture base) with good adhesion and no change in the shape of the artificial tooth, a method that locally heats only the root of the artificial tooth is applied. . The preheating temperature for the root of the artificial tooth is 80 to 300℃.
is necessary. If the temperature is less than 80°C, the preheating effect will be poor and the adhesion between the artificial tooth and the denture base will be inadequate. Also
If the temperature exceeds 300°C, the strength of the artificial tooth will be significantly reduced due to softening and deformation, thermal deterioration, residual strain due to heat, etc., which is not preferable. 100 more
A temperature of ~270°C is preferable because there is no change in the shape or strength of the artificial tooth and higher adhesion with the denture base is obtained. Hereinafter, the present invention will be specifically explained with reference to Examples, but these are illustrative of preferred embodiments and are not limited to the scope of the Examples. Example 1 According to the artificial tooth fracture test method described in the Japanese Industrial Standard JIST-6511, an artificial tooth 1 made of polyether sulfone (Victrex 200P manufactured by ICI) was placed between the incisal end 1' and It was planted on a paraffin wax model so that the line connecting the tooth neck 1" was at a 45° angle with the paraffin wax model, and after being buried in plaster, it was poured with wax to form a plaster mold. The plaster mold was placed on the upper part (artificial The one with built-in teeth) is divided into two parts at the bottom, and placed on top of the plaster mold in the lower flask.
A plate-shaped molded product of polyether sulfone colored to resemble gums was placed and softened by blowing hot air at 380°C for 5 minutes. Next, hot air at 220°C was blown onto the root of the artificial tooth made of polyether sulfone in the upper flask for 2 minutes to preheat it, and the upper and lower flasks were put together and compression molded, followed by natural cooling. After cooling, the upper and lower flasks were divided, and the molded product for the artificial tooth fracture test was taken out. As shown in FIG. 1, the resin bed portion 2 was fixed with a holder 3, and the other artificial tooth end portion 1' was subjected to a fracture test with a predetermined metal fitting 4 at a loading rate of 12 kgf/min. The fracture strength was 28 Kgf, a sufficiently high value that poses no problem in practical use. Comparative Example 1 An artificial tooth made of polyether sulfone was molded under the same conditions as in Example 1 without preheating, and an artificial tooth fracture test was conducted. The fracture strength was only 7 kgf, a low value that would pose a practical problem. Comparative example 2 Artificial teeth formed with polyether sulfone
When molded under the same conditions as Example 1 except for preheating by blowing hot air at 330°C for 2 minutes,
The deformation of the artificial tooth was large and a good molded product could not be obtained. Example 2 A flask in which a wax model of a denture base in which an artificial tooth made of polysulfone (Udel P1700 manufactured by UCC) was implanted was heated to soften and wax the wax, and then the wax was colored to resemble the gums of polysulfone. The U-shaped molded product was placed on a plaster mold in the lower flask, and the molded product was softened by blowing hot air at 350°C. Next, hot air at 190° C. was blown onto the root of the artificial tooth made of polysulfone in the upper flask for 2 minutes to preheat it, and then the upper and lower flasks were put together and compression molded, followed by natural cooling. After cooling, the upper and lower flasks were separated and the denture base was taken out. A denture base was obtained in which the artificial tooth was firmly planted without easily coming off even when the artificial tooth was strongly pressed. Comparative Example 3 An artificial tooth made of polysulfone was molded under the same conditions as in Example 2 without preheating, and a denture base was formed. However, the artificial tooth was removed from the denture base by just being lightly pressed.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of an artificial tooth fracture test. 1...Artificial tooth, 1'...Incisal end of artificial tooth, 1''...
...Cervical part of artificial tooth, 2... Resin base part, 3... Holder, 4... Artificial tooth tensioning fitting.

Claims (1)

[Claims] 1. A method of manufacturing a denture base by placing a thermoplastic resin material on top of the plaster mold in the lower flask and heating it to soften it, then placing the plaster mold in the upper flask containing the artificial tooth on top of it and performing compression molding. A method characterized in that the root of the artificial tooth is preheated to 80 to 300°C and then compression molded.