JPH0231973B2 - GISHISHOSEIKEIHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a denture base molding method that uses a thermoplastic resin as a material and has improved moldability when producing a denture base by compression molding. Conventionally, injection molding is known as a method for manufacturing denture bases using thermoplastic resin, but compression molding was unknown. The present inventor developed the above-mentioned compression molding method and filed a patent application (Japanese Unexamined Patent Publication No. 1439-1988). The method is to obtain a denture base by placing thermoplastic resin softened by heating onto a plaster mold in a lower flask, and then compression molding the upper and lower flasks together. The first cross-sectional view of the plaster mold used in this method is
As shown in the figure. In the figure, an upper flask 1 contains a plaster mold 3 in which an artificial tooth 2 is housed. lower flask 4
Contains a plaster model 7. A lower flask 4 contains a gypsum mold 5 in which a gypsum model 7 is embedded. A denture base is formed within a mold cavity 6 formed between the upper and lower plaster molds. Line 8 is the dividing line between the upper and lower plaster molds. As can be seen from Figure 1, the above-mentioned plaster-shaped mold cavity has severe irregularities and is not uniform, and the artificial tooth is built in the upper plaster-shaped part of the convex part of the alveolar ridge of the plaster mold, and this part is the denture. It is the thickest part of the floor. In addition, the maxillary palate has a complex appearance, as it has become thinner due to the need to sense the taste and temperature of food. As a result of research, the present inventor found that when the dividing line of the upper and lower plaster molds, which is conventionally applied in the above molding method, is flush with each flask frame and there is no accumulation of excess wood, a good denture base is stable. I learned that you can't get it by doing it. In other words, if more resin is used than is required to fill a given mold cavity, the resin that protrudes from the mold cavity will spread into the joint between the upper and lower flasks, thereby widening the gap. Forms a thick burr (an extra part that protrudes from a given molded product) on the molded product. This requires a great deal of effort for finishing, such as removing burrs after molding. In addition, depending on the position where the heated and softened resin is placed, the resin may not penetrate into the thickest parts, such as the convex part of the alveolar ridge, and thick burrs may occur, but the resin may not be deposited on the lower part of the artificial tooth. It was found that this resulted in molding defects such as the formation of filled parts. The purpose of the present invention is to achieve good results in the above compression molding method, that is, to ensure that artificial teeth are firmly implanted;
To provide a method for stably obtaining a denture base without sink marks and from which burrs can be easily removed. The present invention is characterized in that a plaster model in which a wax denture is formed is embedded in a lower flask having a step in the center of the upper peripheral surface of the frame, and elasticity is created between the plaster model and the step. After placing the sheet-like material containing the mold, attaching the upper flask, and secondary embedding the plaster model, the wax is softened and simmered, and the sheet-like material is removed.
The object is to obtain a denture base by using the above-mentioned compression molding. Further, one embodiment will be described with reference to illustrative drawings. Fig. 2 is a perspective view of the lower flask used in the present invention, and Fig. 3 shows the elasticity placed between the plaster model embedded in the lower flask and the step provided on the upper peripheral surface of the lower flask frame. 1 shows one shape of a sheet-like article. Further, FIG. 4 shows a sectional view of a state in which a plaster model is buried in the upper and lower flasks and the sheet-like material is located between the upper and lower flasks. In FIG. 2, a step 9 is provided at the center of the upper peripheral surface of the frame of the lower flask 4. As shown in FIG. 4, a plaster model 7 on which a wax denture 10 is formed is first embedded in the lower flask 4 with plaster, and a sheet having elasticity as shown in FIG. 3 is placed between the plaster model 7 and the step 9. After positioning the shaped object 11, the upper flask 1 is attached, and after the plaster model is secondarily embedded, the upper and lower flasks are clamped and fixed. The clamped flask is placed in hot water at 80°C to soften the wax denture 10, and then the flask is divided, the wax is removed, and the sheet material 11 is removed to form a predetermined mold cavity. A denture base is obtained by compression molding a thermoplastic resin using the plaster mold obtained as described above. FIG. 5 shows a state in which the thermoplastic resin softened by heating is placed on the plaster mold and before compression molding is performed by lowering the upper flask. In FIG. 5, a lower flask 4 contains a plaster mold 5 in which a plaster model 7 is embedded. A thermoplastic resin 12 softened by heating is placed on the plaster model 7. A denture base is molded within the mold cavity 6 formed between the upper and lower plaster molds. The upper and lower plaster models are shown in FIG. 6, and after compression molding, the mold cavity is filled with resin, and the excess resin is poured into the cavity from which the sheet-like material 11 in FIG. It shows a state where the water is flowing out onto a step 9 provided in the water. By molding in the above method, sheet-like material 1
The removed cavity 1 functions as a resin reservoir for excess resin, and the step 9 of the lower flask further functions as an outlet for excess resin 13.
Excess resin will not spread at the joint between the upper and lower flasks and will not form thick burrs around the molded product. Furthermore, by making the sheet-like material 11 of an elastic material, the sheet-like material deforms moderately elastically when the upper and lower flasks are put together during the formation of the plaster mold as shown in FIG. Since it is spread during the process and does not create sharp irregularities on the surface of the plaster mold, damage such as chipping of the plaster mold is less likely to occur during compression molding using thermoplastic resin after the sheet material has been removed. In addition, excess resin flows out smoothly, and a cavity that functions well as a resin reservoir is obtained. After molding using the above method, the flask was divided, the plaster mold was removed, and the molded denture base was taken out. There were no sink marks or filling defects, the adhesion between the artificial tooth and the denture base was good, and the mold cavity size was A molded product faithful to the above was obtained. It is necessary that the elastic sheet-like material and the step provided on the lower flask have the above effects, and the thickness of the sheet-like material is preferably 0.5 to 5 mm, and the step is preferably about 1 to 10 mm. The thermoplastic resin used in the present invention does not undergo thermal deterioration through the molding method, has an appropriate viscosity, has good moldability, and can be colored to resemble the color of the gums. It is required that the resin has appropriate rigidity and moisture resistance, and is strong 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-based resins such as Polysulfone resins 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 randomly or orderly 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]. The thermoplastic resin denture base molding method of the present invention uses a lower flask with a step in the center of the upper peripheral surface of the frame.
A plaster model with a wax denture formed thereon is embedded, an elastic sheet is placed between the plaster model and the step, an upper flask is attached, and the plaster model is secondarily embedded. The thermoplastic resin is compression-molded using a plaster mold obtained by softening and flowing the sheet material and removing the sheet-like material, which has the following effects. (1) During compression molding, excess resin spreads into the cavity created by removing the sheet material and the step in the lower flask, and does not widen the gap between the flasks, so thick burrs are not formed. (2) Since the resin is not deposited on the divided surface of the flask, the alveolar ridge is sufficiently filled with resin, and pressure is evenly applied, resulting in good adhesion between the resin and the artificial tooth. Furthermore, a product that is faithful to the dimensions of the mold cavity can be obtained without making the maxillary palate too thick. (3) After the alveolar ridge is sufficiently filled with resin, excess resin is discharged from the cavity created by removing the sheet material and the step in the lower flask, so that excessive pressure is not applied to the molded product. , cracks due to residual stress are less likely to occur. Further, since the removal of the resin protruding from the molded product is limited to only the cavity created by removing the sheet-like material and the part corresponding to the step of the lower flask, post-finishing is easy.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventionally used plaster mold for forming a denture base. Figure 2 is a perspective view of the lower flask used in the present invention, Figure 3 is an elastic sheet placed between the plaster model and the step provided on the upper peripheral surface of the lower flask frame, and Figure 4 is the book. FIG. 5 is a cross-sectional view showing the state in which the plaster model is buried in the upper and lower flasks and the sheet-like material is located between the upper and lower flasks; FIG. 5 is a cross-sectional view showing the state before compression molding of the present invention; , FIG. 6 is a sectional view showing the compression molded state of the present invention. 1... Upper flask, 2... Artificial tooth, 3... Plaster mold, 4... Lower flask, 5... Plaster mold, 6...
... Mold cavity, 7 ... Plaster model, 8 ... Parting line of plaster mold, 9 ... Step on the upper circumferential surface of the lower flask, 10 ...
臘denture, 11... Elastic sheet-like material, 12
...Thermoplastic resin, 13... Surplus resin.

Claims (1)

[Claims] 1. A plaster model in which a wax denture is formed is embedded in a lower flask having a step in the center of the upper peripheral surface of the frame, and an elastic sheet-like material is placed between the plaster model and the step, After attaching the upper flask and secondary embedding of the plaster model, the wax was softened and waxed, and the sheet was removed. Using the plaster mold obtained, the thermoplastic resin was compression molded. A molding method characterized by obtaining a denture base.