JPH07227400A - Preparation of denture base - Google Patents

Abstract

PURPOSE:To provide a method for preparation of a denture base wherein mold release is good and time for polymn. is unnecessary and there exists no problem accompanied with polymn. and an exclusive plaster mold being durable to high temp. is not needed and adhesiveness between the denture base and an artificial tooth is excellent. CONSTITUTION:Polymethyl methacrylate is used as a resin R. After this resin is softened by heating, it is injected into a plaster mold S for a denture base formed in a flask F. The injected resin R is naturally cured to obtain the objective denture base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a denture base or the like, and more particularly, to a denture base or the like for obtaining a denture base or the like by pressing a resin into a plaster mold formed in a flask and curing the resin. It relates to a manufacturing method.

[0002] In this specification, a denture base and the like include not only a denture base but also a crown.

[0003]

2. Description of the Related Art Conventionally, as a method for producing a denture base or the like, as a resin, a polymer such as powdery polymethylmethacrylate (PMMA) and a monomer such as liquid methylmethacrylate (MMA) are mixed to form a dough. It is common practice to use a mold and press it into a gypsum mold formed in a flask for polymerization. To polymerize the resin, heat the flask in a water bath, boil it for about 30 minutes, and then polymerize the resin for 30 to 40 minutes. Put the flask in boiling water at 100 ° C and heat it for 10 to 15 minutes. The heat shock method to polymerize the resin, the microwave method to heat the resin from the inside of the flask to polymerize it by irradiating the microwave of 2450MHz with a microwave oven, the room temperature polymerization to polymerize the resin by leaving the flask at room temperature, etc. Used.

Polycarbonate (P
It is also known to use C), polysulfone (PSF) or polyether sulfone (PES), which is softened by heating and pressed into a plaster mold to be hardened.

[0005]

Among the conventional methods for manufacturing a denture base, etc. described above, a method of press-molding a dough-shaped mixture of a polymer and a monomer into a gypsum mold to polymerize The low viscosity of the resin due to the inclusion of the monomer causes the resin to get into the microscopic voids on the inner surface of the gypsum mold, making it difficult to separate from the mold.Therefore, it is necessary to apply a separating material such as sodium alginate before injecting the resin. In addition, there is a problem that the molded product cannot be separated properly even if the separating material is applied. Furthermore, it takes a long time for the polymerization, and as a problem with the polymerization, the doughing time is as long as 15 minutes to 30 minutes and the reaction is gradually performed.
It is difficult to press the resin into the gypsum mold at a difficult time, the workability is poor, and there are variations, and in microwave polymerization, the polymethylmethacrylate in the part in contact with the reinforcing metal part causes a burning phenomenon due to sparks. was there. Furthermore, if the resin is pressed in when the temperature of the gypsum mold is room temperature or higher, white turbidity or bubbles are generated, so that there is a problem that the temperature of the gypsum mold is limited to the temperature of room temperature or lower.

In the conventional method for producing a denture base, etc., the method using polycarbonate, polysulfone or polyether sulfone has a high melting point because the polycarbonate, polysulfone or polyether sulfone used as a resin has a high melting point. It also becomes expensive, requires a dedicated plaster mold that can withstand high temperatures, is costly,
There was a problem that the work was troublesome. In addition, there is also a problem that when a denture base is formed with these resins, the adhesive force to artificial teeth made using polymethyl methacrylate is weak.

The object of the present invention is that the mold release is good, there is no need for polymerization time, there are no problems associated with polymerization, there is no need for a dedicated gypsum mold that withstands high temperatures, and there is a denture base and a polymethylmethacrylate artificial body. It is an object of the present invention to provide a method for producing a denture base or the like, which has excellent adhesion to teeth.

[0008]

The method for producing a denture base etc. according to the present invention is a method for producing a denture base etc. wherein a resin is pressed into a plaster mold formed in a flask and cured to obtain a denture base etc. The resin is characterized in that polymethyl methacrylate is used as the resin and is softened by heating before press-fitting.

The amount of polymethylmethacrylate ranges from 5 g
100 g, more preferably 10 g to 55 g, the heating temperature before press fitting is 200 ° C. to 370 ° C., more preferably 240 ° C.
C. to 300.degree. C., and the heating time is 3 minutes to 60 minutes, more preferably 3 minutes to 20 minutes.

The pressure applied during press-fitting is 700 to 3000 kg when a hydraulic press unit "Sulfone Jet 3000" manufactured by Hydental Service Co., Ltd. is used.
(35 to 152 kg / cm ² ), more preferably 800
〜1500 kg (40 to 76 kg / cm ² ), the pressure for curing after press fitting is 100 to 1000 kg (5 to 5 kg
1 kg / cm ² ), more preferably 100 to 300 kg
(5 to 15 kg / cm ² ).

[0011]

In the method for producing a denture base or the like according to the present invention, polymethyl methacrylate is used as a resin and is softened by heating before press-fitting. Therefore, the press-fitted polymethyl methacrylate is allowed to stand for a while. If you put
The temperature lowers and it hardens naturally.

Further, since the resin is cooled when it is pressed into the gypsum mold, it is difficult for the resin to enter the fine voids on the inner surface of the gypsum mold.

Also, polymethylmethacrylate has a lower melting point than polycarbonate, polysulfone and polyethersulfone and does not require a dedicated gypsum mold that can withstand high temperatures.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an injection molding apparatus (A) used in a method for manufacturing a denture base etc. according to the present invention. The apparatus (A) has two vertical guide rods (left and right). 1) A table (2) that can be moved up and down along with a hydraulic press unit (3) that moves the rod (3a) up and down by a hydraulic mechanism to move the table (2) up and down, and a guide rod (1). A top support member (6) having a downwardly projecting slide bush (5) which is provided horizontally over each upper end of the and has a through hole (4) and a passage communicating with the through hole (4); A spring accommodating portion (7) provided at the position of the through hole (4) on the upper surface of (6), and a push spring (8) accommodated in the accommodating portion (7),
Piston rod (10) that is inserted into the passage of through hole (4) and slide bush (5) and is urged downward by push spring (8) and has resin pressing piston (9) at the lower end
Mounted on a table (2) and with a resin inlet on the top
A flask (F) having (11), a cylinder (13) having a resin passage (12) communicating with the resin inlet (11) on the bottom wall and located below the piston (9), and a resin passage (12). ), And an aluminum plate (14) arranged inside the cylinder (13) so as to cover the above.

In this embodiment, "Sulfone Jet 3000" manufactured by Hydental Service Co., Ltd. is used as the hydraulic press unit (3).

The table (2) is provided with table through-holes (15) for inserting guide rods on both sides, and has an upward projecting slide bush (16) having a passage communicating with the table through-hole (15). ) Is provided. Guide rod
(1) is the top support member when the table (2) is raised.
A table lift release spring (17) that is compressed between the table (6) and the table slide bush (16) is inserted. A spring retainer plate (18) is provided on the upper end of the piston rod (10). The lower end of the slide bush (5) contacts the upper surface of the piston (9) when the piston rod (10) rises. In this embodiment, the aluminum plate (14) has a thickness of 0.6 mm and is set so as to break at a pressure of about 76 kg / cm ² . Flask (F) consists of left and right flask lids (F1) (F4) and left flask (F) as shown in Figs.
2) and right flask (F3), which are connected and fixed by a plurality of bolts (31) and nuts (32). The method for forming a plaster mold (S) such as a denture base in the flask (F) is
A conventional method that has been conventionally used may be used.

Below, using the above-mentioned injection molding apparatus (A),
A method for producing a denture base supporting the artificial tooth (T) made of PMMA by using polymethylmethacrylate (PMMA in the examples) (R) as the resin (R) will be described.

First, the cylinder (13) is loaded with the plate (14) and placed on the recess (33) in the aluminum block (32) of the resin melting heater (31) shown in FIG. Then, PMMA (R) is put into the cylinder (13) and heated and melted while being pressurized with a pressure rod. The heating temperature at this time is, for example, 280 ° C., and the heating time is about 10 minutes.

Before injecting PMMA (R), the flask (F) was once divided into right and left, and the surface of the gypsum mold (S) was coated with a photocurable resin and then irradiated with ultraviolet rays and visible light. It is preferable to cure the photocurable resin by
This makes it possible to prevent the thermoplastic resin from being deteriorated by the vaporized water in the gypsum when the thermoplastic resin is injected and injected into the gypsum mold (S).

When the melting of PMMA (R) is completed, a small amount (about 5 grams) of unmelted PMMA (R1) is charged into the cylinder (13). As a result, in the cylinder (13), a layer of unmelted PMMA (R1) is formed above the layer of melted PMMA (R), so that the molten PMMA (R) flows backward during pressurization. Can be prevented. Silicone packing (P) is further arranged in the cylinder (13) taken out from the resin melting heater (31), and the state shown in FIG. 2 is obtained.

The cylinder (13) containing the PMMA (R) in a molten state is connected to the resin inlet (11) and the resin passage (1).
2) Place it in the recess (35) of the flask (F) so that
Set these on table (2) (see Figure 3). The temperature of the gypsum mold (S) at this time is not limited to room temperature or lower, and the temperature of the gypsum mold may be about 0 to 130 ° C.

Next, when the table (2) is raised, the resin pressurizing piston (9) is inserted into the cylinder (13) and the PMMA (R) is pressurized by the piston (9). At the same time, the pressing spring (8) is compressed by the spring pressing plate (18). The upper surface of the resin pressurizing piston (9) contacts the lower end of the slide bush (5), and the PMMA
(R) is pressurized by the resin pressurizing piston (9). At this time, the lower end of the slide bush (5) is inserted into the cylinder (13) together with the piston (9), and the push spring is
(8) remains compressed (see Figure 4).

When PMMA (R) was further pressurized by the resin pressurizing piston (9), the plate (14) broke and was compressed at the same time when the pressure of about 76 kg / cm ² was reached. The repulsive force of the push spring (8) pushes down the resin pressurizing piston (9) at high speed, and from the breaking point, the resin passage (12) of the cylinder (13) and the flask (F).
PMMA into the plaster mold (S) through the resin injection port (11) of
(R) is injected at high speed. Plaster mold for flask (F)
When PMMA (R) spreads in (S), the resin pressurizing piston (9) stops descending, but the pressing spring (8) causes about 1
A pressure of about 5 kg / cm ² is maintained (see FIG. 5).

The PMMA (R) in a molten state, which is injected and injected into the plaster mold (S) of the flask (F), is left to stand for a while, the temperature thereof is lowered, and the PMMA (R) is naturally hardened. After curing the PMMA (R), the flask (F) is divided into left and right parts, and the molded product inside is taken out. Since PMMA (R) has good mold release, it can be taken out easily and in a clean state.

Since the molded product obtained by injection injection of PMMA (R) contains some internal stress, as a method for improving the accuracy of the molded product, a flask ( It is desirable to heat F) at 110 to 130 ° C for about 1 hour to release the internal stress.

According to the method for manufacturing a denture base etc. of the present invention,
It is also possible to manufacture a crown by changing the plaster mold (S). 9 and 10 show a plaster mold (S1) used for manufacturing a crown, and the plaster mold (S1) includes a central artificial tooth portion (T1) and a residual tooth by sandwiching the same. And a pair of crown portions (T2) to be covered with the. Flask (F)
Is the same as that of FIGS. 6 and 7. This plaster mold (S
1) is used, PMMA (R) is heated by a melting heater (31) at, for example, 280 ° C. for about 10 minutes, and then a plaster mold (S1)
A dental crown made of PMMA is obtained by injection-injecting it into the interior and naturally curing it.

[0028]

EFFECTS OF THE INVENTION According to the method for manufacturing a denture base etc. of the present invention, the pressure-injected polymethylmethacrylate decreases spontaneously as the temperature lowers if left for a while, so that no polymerization time is required and the polymerization is not required. No problems will occur.

Further, since the resin is cooled when it is pressed into the plaster mold, it is difficult for the resin to enter into the minute voids on the inner surface of the plaster mold, so that the mold is separated easily and the separating material is applied before the resin is injected. It is unnecessary.

Further, since polymethylmethacrylate has a lower melting point than polycarbonate, polysulfone and polyethersulfone and does not require a dedicated gypsum mold that can withstand high temperatures, the cost does not increase and the operation is not troublesome.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an apparatus used in a method for manufacturing a denture base etc. according to the present invention.

FIG. 2 is an enlarged sectional view showing a cylinder of the apparatus.

FIG. 3 is an enlarged sectional view of an essential part showing a state before resin pressurization.

FIG. 4 is an enlarged sectional view of an essential part showing a state when the resin is pressurized.

FIG. 5 is an enlarged sectional view of an essential part showing a state after resin injection.

FIG. 6 is a sectional view of a flask.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a perspective view showing a melting heater.

9 is a sectional view corresponding to FIG. 6, showing another embodiment of a plaster mold used in the method for manufacturing a denture base etc. according to the present invention.

10 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 (A) Injection molding machine (F) Flask (R) Resin (S) (S1) Gypsum mold (31) Melting heater

Claims (1)

[Claims] 1. A method for producing a denture base or the like in which a resin is pressed into a plaster mold formed in a flask and cured to obtain a denture base or the like, wherein polymethylmethacrylate is used as the resin, A method for producing a denture base or the like, which comprises heating and softening.