JPH0219128Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention uses a denture base forming device, particularly when forming a denture base using polymethyl methacrylate (hereinafter referred to as PMMA) resin, to reduce the shrinkage that occurs during polymerization and solidification of PMMA. The present invention relates to a denture base forming device capable of correcting.

<Conventional technology> PMMA has conventionally been used as a denture base material. For molding methods using such materials,
After dissolving PMMA powder in liquid methyl methacrylate (hereinafter referred to as MMA) monomer and making it into a rice cake shape, this is filled into a denture base forming space previously formed using plaster in the hollow space inside the flask, and then placed in boiling water or in a pressure cooker. The rice cake-like PMMA is polymerized and solidified by heating to approximately 100°C to 130°C. However, in such a method, a portion of the liquid MMA monomer evaporates, resulting in a volume change due to PMMA polymerization and hardening, causing shrinkage in the formed denture base, which may not match the jaw model made of plaster. There are many. The shrinkage of the above PMMA is usually about 1.8 ~
It is 2.0%. The above-mentioned incompatibility of the denture base with the alveolar ridge due to contraction has become a problem in recent years, such as causing tenderness during mastication.

The above-mentioned shrinkage correction device when thermoplastic resin is used as the denture base material is, for example, disclosed in U.S. Pat.
145609 and Utility Model Application Publication No. 58-145610, the apparatus disclosed in the above-mentioned publications cannot be applied to the method of filling a plaster mold with rice cake-like PMMA and then polymerizing it by heating. This is because if PMMA for shrinkage correction is heated or exists outside the flask, it will polymerize and harden, making it impossible to correct shrinkage.

<Problems to be solved by the invention> The present invention was created in view of the above-mentioned circumstances, and corrects the shrinkage by separately replenishing the space created by the contraction of the rice cake-like PMMA with rice cake-like PMMA. This provides a denture base with a shape that perfectly matches the jaw model.

<Means for Solving the Problems> The denture base forming device according to the present invention includes first and second flasks forming a hollow space, a hole drilled in the first flask, and a denture base forming device arranged on the hole. an elastic body, a compression means for compressing the elastic body to generate an elastic force therein, and a denture base forming area formed of plaster in the hollow space and a PMMA reservoir continuous thereto;
The PMMA is polymerized and hardened while being filled with rice cake-like PMMA and applying elastic force from the elastic body to the PMMA reservoir through the hole.

<Function> Mochi-like PMMA is formed in the denture base forming area and PMMA reservoir, which are pre-formed with plaster filled in the flask.
After filling, when the compression means is operated to compress the elastic body, the elastic force from the elastic body is applied to the PMMA reservoir and elastically presses the rice cake-shaped PMMA filled therein. In this state, the flask is heated to about 100°C to 130°C in a polymerization atmosphere such as boiling water or a pressure cooker.
When heated at a temperature of , the polymerization and hardening reaction of the rice cake-like PMMA proceeds sequentially starting from the outer edge of the denture base (buccal side).
The sparse areas created by the contraction are replenished by extrusion of cake-like PMMA from the PMMA reservoir. In this way, the final part of the flask and the PMMA
Polymerization progresses in the reservoir and the formation of the denture base is completed.

<Example> In the figure, 1 is a first flask, and 2 is a second flask, each of which is made of metal and has a structure that can be divided into two parts, and these divided parts are fixed with screws or the like. 3 and 4 are the first and second respectively
With gypsum filled in the hollow spaces inside flasks 1 and 2,
The plaster 4 in the second flask 2 forms a jaw model, and the plaster 3 in the first flask 1 forms a denture external shape. 5, 5 is the plaster 3 of the first flask 1
This is an artificial tooth that is implanted inside. A mold release agent 6 is applied between the plasters 3 and 4 of the first and second flasks 1 and 2, and both flasks 1 and 2 are fastened and fixed with screws (not shown) or the like. 7 is plaster 3,
In the denture base forming area formed by 4, the denture base forming area is filled with a rice cake-like PMMA 8 formed by dissolving and kneading powdered PMMA into liquid MMA monomer. 9, 9 is a mochi-shaped area leading to the denture base formation area 7
The PMMA reservoir is also filled with rice cake-like PMMA8. The cake-like PMMA reservoirs 9, 9 are formed at or near the center of the flasks 1, 2 so that polymerization is carried out last. 10 is a heat insulating plate such as a rubber plate embedded in the plaster 4 of the second flask 2;
Although it has the effect of making it difficult for heat to be transferred from the outside to the rice cake-like PMMA reservoirs 9, 9, experiments have confirmed that the intended purpose can be achieved even without this heat insulating plate 10. 11 is a hole made in the first flask 1, and 12 is a mochi-shaped through this hole 11.
It is a Y-shaped molded body made of thermoplastic resin that reaches the PMMA reservoirs 9, 9, and functions as an elastic force transmission means. As the material for the molded body 12, an olefin thermoplastic resin that exhibits plasticity at around 50°C and becomes fluid at about 100°C or higher is suitable. In addition, it is also possible to use clay or the like as the molded body 12. In the illustrated example, the shape is Y-shaped, but the shape is not limited to this, and the shape is not limited to a straight shape or may be formed into any other shape depending on the shape of the denture base. The molded body 12 is positioned and buried in the plaster 3 when the plaster 3 is poured into the first flask 1. Reference numeral 13 denotes a metal cylindrical body, which has a threaded groove 14 formed on its lower inner circumferential surface, and is screwed into a threaded groove similarly formed in the first flask 1. Reference numeral 15 denotes a guide body into which one end of the molded body 12 is inserted into a hole provided at its center, and the lower end is fitted into the hole 11 of the first flask 1 . Reference numeral 16 is a movable body disposed within the cylindrical body 13 so as to be movable up and down, and has a cylindrical pin 17 formed at the lower center of a metal disk.
comes into contact with the end surface of the molded body 12. Reference numeral 18 denotes a rubber ball placed on the upper surface of the moving body 16, which acts as an elastic body. A coiled spring may be used instead of the rubber ball 18. Reference numeral 19 is a metal disc that is placed above the rubber ball 18 and moves up and down within the cylindrical body 13, and 20 is a bolt that presses the disc 19 downward and is screwed to the cylindrical body 13.
The bolt 20 serves as a compression means for the elastic body 18. The illustrated state is the denture base formation area 7 and the mochi-shaped
The PMMA reservoirs 9, 9 are filled with rice cake-like PMMA, and at this time, the upper end position of the molded body 12 is such that there is a certain distance between the disk portion of the movable body 16 and the upper end surface of the guide body 15. Its height is set. In this state, the bolt 20 is rotated as shown by arrow a and screwed downward in the figure. As a result, the disk 19 descends and compresses the rubber ball 18, deforming it into an elliptical shape. This is shown by the broken line in the figure. Since such an operation is performed in an atmosphere at room temperature, the molded body 12 maintains a solid state, and as a result,
The elastic force generated by the rubber balls 18 is not transmitted to the cake-like PMMA reservoirs 9, 9. If, for example, clay is used as the molded body 12, the elastic force from the rubber balls 18 is transmitted to the PMMA reservoir 9 even at room temperature, but there is no problem because the denture base forming area 7 is a closed space. After that, the first and second flasks 1 and 2
is placed in boiling water or a pressure cooker while being fastened and heated at about 100°C to 130°C for about 10 to 20 minutes. As a result, the temperature increases from the outer walls of flasks 1 and 2 toward the inside, and PMMA8
is polymerized and solidified starting from the periphery. At the same time, the temperature of the flasks 1 and 2 and the plasters 3 and 4 increases, causing the molded body 12 to soften and flow, and the elastic force of the rubber balls 18 is applied to the cake-like PMMA 8 in the PMMA reservoirs 9 and 9 through this molded body 12. , joins 8. Therefore, the PMMA8 constituting the denture base shrinks due to polymerization, and in the area where PMMA8 becomes sparse,
PMMA-shaped PMMA is newly replenished from the PMMA reservoirs 9, 9. In this case, the elastic force by the rubber ball 18 is an amount corresponding to the replenishment due to PMMA contraction.
The minimum strength required is enough to push out the PMMA. Inside the plaster 3 and 4, including the PMMA reservoirs 9 and 9.
After all PMMA8 is polymerized and solidified, the first and second
The flasks 1 and 2 are divided, and the denture bases to which the artificial teeth 5 and 5 are fixed are taken out. Thereafter, the PMMA 8 in the PMMA reservoirs 9, 9 is removed by polishing.

<Effects of the invention> This invention polymerizes rice cake-like PMMA in a heated atmosphere.
When curing to form a denture base, a PMMA reservoir is formed, and an elastic force is applied to this from the outside to replenish PMMA into the denture base formation area. Deformation due to shrinkage that occurs during this process is prevented, and a denture base with a shape that perfectly matches the jaw model can be obtained.

[Brief explanation of the drawing]

The figure is a sectional view of one embodiment of the present invention. 1...first flask, 2...second flask,
3, 4... Plaster, 5, 5... Artificial tooth, 7... Denture base formation area, 8... PMMA, 9, 9... PMMA
Reservoir, 10... Heat insulating plate, 11... Hole, 12... Molded body, 13... Cylindrical body, 15... Guide body, 16
...Moving object, 18...Rubber ball, 19...Disc, 2
0...Bolt.

Claims (1)

[Claims for Utility Model Registration] (1) First and second flasks forming a hollow space, a hole bored in the first flask, an elastic body disposed over the hole, and a compressor that compresses the elastic body. , which is equipped with a compression means that generates an elastic force, and fills the denture base forming region formed of plaster in the hollow space and the PMMA reservoir continuous thereto with the mochi-like PMMA, and the elastic body With the elastic force applied to the PMMA reservoir through the hole,
A denture base forming device characterized by polymerizing and curing the above-mentioned PMMA. (2) The denture base forming device according to claim 1, wherein the elastic body is a rubber ball. (3) Practical use characterized in that an elastic force transmission means reaching the PMMA reservoir from the hole is interposed, and the elastic force of the elastic body is applied to the PMMA reservoir through the elastic force transmission means. A denture base forming device according to claim 1 of the patent registration claim. (4) The denture base forming device according to claim 3, wherein the elastic force transmitting means is made of thermoplastic resin.