JPH0221054Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> This invention is aimed at reducing the shrinkage that occurs during polymerization and solidification of PMMA when molding a denture base using a denture base molding material, particularly polymethyl methacrylate (hereinafter referred to as PMMA) resin. The present invention relates to a replenishment device for denture base molding material that can correct the denture base molding material.

<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 was filled into a denture base forming space previously formed using plaster in a hollow space inside a pair of flasks, and then heated in boiling water or steam. The rice cake-like PMMA is polymerized and solidified by heating it to about 100°C to 130°C in a pressure cooker.
However, with this method, some of the liquid MMA monomer evaporates, and a volume change occurs 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 PMMA above is usually about 1.8-2.0
%, PMMA weight approximately 0.2 per complete denture
It is about 0.3g. The above-described incompatibility of the denture base with the alveolar ridge due to shrinkage has become a problem in recent years, such as causing poor adhesion of the denture, tooth movement, or 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.
No. 145609 and Utility Model Application Publication No. 58-145610, however, the method of filling a plaster mold with rice cake-like PMMA and then heating and polymerizing it cannot be applied to the apparatus disclosed in the above-mentioned publications. This is because if PMMA for shrinkage correction is heated or exists outside the flask, it will polymerize and solidify, making it impossible to correct for shrinkage.

<Problems to be solved by the invention> The present invention was made in view of the above-mentioned circumstances, and aims to correct the shrinkage by separately replenishing the space created by the contraction of the rice-cake-like PMMA with rice-cake-like PMMA. The present invention also provides a denture base molding material replenishment device that can obtain a denture base having a shape that perfectly matches the alveolar ridge.

<Means for Solving the Problems> The denture base molding material replenishment device according to the present invention includes a cylinder having an opening at one end, a piston that moves within the cylinder, and a piston that is housed in the cylinder and moves within the cylinder. It is made of an elastic body that elastically presses the denture base, and is embedded and fixed in plaster adjacent to the denture base formation space.

〈Action〉 A mochi-like shape is formed in the denture base formation space formed with plaster.
When the PMMA resin is filled with a predetermined pressure, the pressure of the resin presses the piston of the refilling device. This pressing force compresses and deforms the elastic body, and the piston moves slightly inside the cylinder. An extra amount of mochi-like PMMA resin is replenished by the amount of piston movement, and this is replenished when the denture base contracts to compensate for the contraction.

<Example> In FIG. 1, a replenishment device 1 includes a cylinder 2 made of a hard material such as plastic or metal and having an opening at one end, and a cylinder 2 that is housed within the cylinder 2 and slides on the inner surface of the cylinder 2. piston 3
and elastic bodies, such as rubber balls 4, 4, 4, which are housed in the cylinder 2 and elastically press the piston 3.
Consists of. A screw-in type lid member 5 is attached to the other end of the cylinder 2. This is to facilitate removal of plaster or the like when it enters the elastic body space 6 that is substantially sealed by the piston 3. The piston 3 is made of a hard member such as plastic or metal.

FIG. 2 shows the replenishing device 1 embedded in plaster 7, 7, 8 is a cake-shaped PMMA resin filled into the denture base forming space 9, and 10 is an artificial tooth. 11 is
This is a reservoir of rice cake-shaped PMMA resin 8 provided between the denture base forming space 9 and the replenishing device 1. The cake-like PMMA resin 8 is filled into the denture base forming space 9 with considerable pressure. Due to this pressure during filling, the rubber bulb 4,
4 and 4 are deformed into elliptical shapes, and the piston 3 moves slightly toward the inside of the cylinder 2 (to the left in the figure) by this deformation. The mochi-shaped PMMA resin 8 is the piston 3
The rubber balls 4, 4, 4 apply elastic force to this increased amount toward the denture base forming space 9. When the rice cake-like PMMA resin 8 contracts during polymerization and solidification, the rice cake-like PMMA resin 8 pushed out from the reservoir 11 by the piston 3 is replenished into the contracted part.
Deformations due to shrinkage are corrected.

FIG. 3 shows the arrangement of the replenishing device 1 in one flask 12. The illustrated example has a structure in which the cake-shaped PMMA resin 8 is injected into the denture base forming space 9 using an injection molding method. In the figure, numeral 13 denotes a sprue hole closing valve made of an elastic member such as rubber, with which an injection nozzle of an injection molding machine comes into contact. 14 is a sprue hole, 15 is an air vent, 16
is a confirmation member for confirming the completion of filling the denture base forming space 9 with the rice cake-shaped PMMA resin 8, and also functions as a resin discharge prevention valve. Replenishment device 1
are arranged adjacent to areas where contraction of the denture base forming space 9 is likely to occur, for example, both ends on the tongue side, with a reservoir 11 interposed therebetween. Reference numeral 17 designates another flask that is superimposed on the flask 12, and both are clamped together with bolts or the like through screw holes 18, 18, . . . . The other flask 17 is filled with plaster like the first flask 12, and a jaw model taken from the patient is formed using the plaster.

Figures 4 to 6 show the sprue hole closing valve 13.
19 is a notch that passes through the center of the sprue hole closing valve 13 from the surface located outside the flasks 12, 17 to the surface located inside the flasks 12, 17.
The width becomes narrower toward the inside. A circular recess 2 having a diameter approximately equal to the notch 19 is formed on the surface located outside the flasks 12 and 17.
0 is provided, and the nozzle of the injection molding machine comes into contact with this. Reference numeral 21 denotes an intermediate projection formed on the outer periphery of the sprue hole closing valve 13, and a corresponding recess 2 is formed in the flasks 12, 17 as shown in FIG.
2 and 23 are provided, and the intermediate protrusion 21 is engaged with and fixed thereto. 24, 24... are four grooves carved in the circumferential direction on the outer periphery of the sprue hole closing valve 13. Sprue hole closing valve 13 having such a structure
can be made of rubber with a JIS hardness of approximately 40 to 80.

To explain the operation of the sprue hole closing valve 13, the nozzle 25 is pressed against the circular recess 20,
When the rice cake-shaped PMMA resin 8 is injected with a predetermined pressure, the cut 19 is expanded by the injection pressure to create an opening, through which the rice cake-shaped PMMA resin 8 flows into the sprue hole 14. The grooves 24, 24... are crushed by the injection pressure,
It acts to facilitate opening. When the filling of the rice cake-like PMMA resin 8 is completed, the injection press-fitting is stopped. When the nozzle 25 is left in contact with the sprue hole closing valve 13 for a while, the sprue hole closing valve 13 elastically returns and the notch 19 is closed. Thereafter, the nozzle 25 is separated from the sprue hole closing valve 13.

7 and 8 show the structure and usage state of the confirmation member 16. FIG. The confirmation member 16 is the flask 1
2, 17 so as to be movable a certain distance in the left and right directions in the figure, and one end of the air vent 15 is connected to the air vent 15.
The other end faces the outside of the flasks 12,17. Therefore, as shown in FIG. 8, the air vent 15 is shaped like a rice cake.
When filled with PMMA resin 8, the confirmation member 16 is
The pressure pushes the flasks 12, 17 toward the outside, and the ends thereof protrude outside the flasks 12, 17. This protrusion confirms that the filling of the rice cake-shaped PMMA resin 8 has been completed. Therefore, confirmation member 1
The final end of the air vent 15 where the air vent 6 is located needs to be set at the space within the flasks 12 and 17 where the cake-shaped PMMA resin 8 reaches the end. It is preferable that the confirmation member 16 is made of an elastic member such as rubber, elastically abuts against the wall surfaces of the flasks 12 and 17, and is supported to such an extent that it does not move under its own weight or with a slight force.

Next, the operation of the denture base forming device incorporating the replenishing device 1 will be explained.

The nozzle 2 of the injection molding machine is connected to the sprue hole closing valve 13 fixed to a pair of clamped flasks 12 and 17.
5, and the rice cake-shaped PMMA resin 8 is applied from the nozzle 25.
Inject. The mochi-like PMMA resin 8 has a cut 1
9 into the sprue hole 14. The cake-shaped PMMA resin 8 filling the denture base forming space 9 is
Thereafter, the air flows to the air vent 15 and stops by pressing the confirmation member 16. When the injection pressure is further maintained, the piston 3 of the refilling device 1 releases the rice cake-like PMMA resin,
8, the rubber balls 4, 4, 4 deform into an oval shape. Thereafter, the injection pressure is maintained for a while until the sprue hole closing valve 13 closes, and then the nozzle 25 is released. Although it is difficult to confirm whether the rice cake-like PMMA resin 8 has been refilled into the replenishing device 1, it can be determined empirically by adjusting the injection pressure of the nozzle 25. Furthermore, if the movable pressure of the confirmation member 16 is set higher than the resin replenishment pressure to the replenishment device 1, the protrusion of the confirmation member 16 will cause the replenishment device 1 to have a mochi-like shape.
Replenishment of PMMA resin 8 can also be confirmed.
After that, the pair of flasks 12 and 17 are placed in a boiling water or steam pressure cooker while being clamped, and the temperature is approximately
Heated at 100°C to 130°C for about 10 to 20 minutes. As a result, the temperature increases from the outer walls of the flasks 12 and 17 toward the inside, and the rice cake-like PMMA resin 8
is polymerized and solidified from the peripheral portion, that is, from the buccal side of the denture base. When the density of the rice cake-like PMMA resin 8 becomes sparse due to the contraction that occurs at this time, the rice cake-like PMMA resin 8 in the reservoir 11 is pushed out through the piston 3 by the elasticity of the rubber balls 4, 4, 4 in the replenishing device 1. The above sparse areas are replenished. After the PMMA resin in the sprue hole 14, air vent 15, and denture base forming space 9 has all polymerized and solidified, the flasks 12 and 17 are divided, the plaster is destroyed, and the denture base to which the artificial teeth 10, 10... are fixed is taken out. Thereafter, the PMMA resin 8 in the sprue hole 14 and the air vent 15 is removed by polishing.

<Effects of the invention> The denture base forming material replenishment device according to the present invention is arranged through a reservoir adjacent to a denture base forming space formed of plaster, and a mochi-shaped material is placed in the space.
When press-fitting a plastic molding material such as PMMA resin,
Since this replenishment device is filled with molding material at the same time, even if the molding material contracts during polymerization and solidification, new molding material is pushed out from the replenishment device, the shrinkage deformation is corrected, and the molding material perfectly matches the alveolar ridge. It is possible to obtain a shaped denture base.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main parts of the replenishment device according to the present invention, and FIG. 2 is a sectional view showing the usage state of the device.
FIG. 3 is a perspective view showing the surface condition of one flask, FIG. 4 is a perspective view showing the sprue hole closing valve,
FIG. 5 is a sectional view taken along the line AA in FIG. 4, FIG. 6 is a sectional view showing how the sprue hole closing valve is used, and FIGS. 7 and 8 are sectional views showing the confirmation member. 1... Replenishment device, 2... Cylinder, 3... Piston, 4, 4, 4... Rubber bulb, 5... Lid member,
7... Plaster, 8... Mochi-like PMMA resin, 9... Denture base formation space, 10... Artificial tooth, 11... Reservoir,
12, 17... Flask, 13... Sprue hole closing valve, 14... Sprue hole, 15... Air vent, 16... Confirmation member.

Claims (1)

[Scope of utility model registration request] When forming a denture base by filling a denture base forming material in a plastic state into a denture base forming space formed of plaster in a pair of stacked flasks, the plaster is placed adjacent to the denture base forming space. The replenishing device replenishes the molding material into the denture base forming space by being implanted, the replenishing device comprising a cylinder having an opening at one end, a piston that moves within the cylinder, and a replenishing device that is housed in the cylinder and that moves the piston with elasticity. and a pressing elastic body, the elastic body being compressed via the piston by the filling pressure of the molding material when filling the molding material into the denture base forming space. Molding material replenishment device.