JPS6058658B2 - Denture base manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a denture base.

Conventionally, dental denture bases are made by mixing acrylic resin polymer powder and monomer liquid to form a rice cake, placing the mixture at room temperature into a plaster mold flask for the mouth stowwax method, and placing it in hot water under pressure using a press. It was produced by polymerization.

While this conventional manufacturing method has the advantage of being able to be operated at room temperature while visually confirming it and being inexpensive to manufacture,
Since polymerization shrinkage of approximately 7% occurs during polymerization, deformation is large and accuracy is extremely poor.

Furthermore, since it is necessary to polymerize in hot water for several hours, the operation time is very long and only a small number can be produced in one day.
Another disadvantage was that thermoplastic resins other than acrylic resins could not be used. Furthermore, in this production method using polymerization, the unreacted synthetic resin kneaded material is once injected into a flask and heated, and the chemical reaction is accelerated by the heat. Due to the uniformity, the conduction of heat to the synthetic resin will also become non-uniform, and there is a great possibility that the product will result in a denture base with low-molecular synthetic resin, that is, a product in which unreacted parts remain in place.

Now, there is a method of manufacturing a denture base by extrusion molding of a thermoplastic resin as a method that eliminates the volumetric shrinkage caused by polymerization. This is a process in which polymer pellets are heated and pressed into a plaster mold as a fluid.
This manufacturing method produces only about 0.7% of cooling shrinkage during cooling, so it has the advantage of being highly accurate and short in operation time, allowing for large quantities to be manufactured. Moreover, not only acrylic resin but also all thermoplastic resins can be used. However, since this manufacturing method involves filling a plaster mold with a heated fluid, it is extremely difficult to set the temperature of the resin, mold, etc., and has the disadvantage that it requires an expensive extrusion molding machine or injection molding machine.

Moreover, since the molding process progresses inside the machine, it cannot be visually confirmed and there is a great risk that the resin will not reach every corner. In view of the above circumstances, it is an object of the present invention to provide a method of manufacturing a denture base with high precision using an inexpensive device. In other words, the feature of the present invention is that the thermoplastic resin is heated and softened on the divided lower flask in a constant temperature condition set at a desired temperature of 100°C to 450'C in accordance with the temperature conditions of the thermoplastic resin. The purpose is to compression mold plastic synthetic resin by combining upper and lower flasks.

Further, one embodiment will be described with reference to illustrative drawings.
In a chamber 1 set at a desired temperature of 100° C. to 450° C., a plaster-shaped flask 2 made by the stowage process and a container 4 each containing one bed of thermoplastic synthetic resin 3 are stored.
Next, the flask 2 is divided into upper and lower parts, and the flask 2 is heated with a thermoplastic synthetic resin 3 heated and softened into an almost candy-like shape.
After placing the flask 2 into the compression molding machine 5, align the flask 2 vertically.
Afterwards, it is transferred to a pressure holder 6 and placed in the chamber 1.
It is taken outside and allowed to cool naturally.

Depending on the type of thermoplastic synthetic resin, the temperature of the flask storage chamber is 1000C to 400C, and the temperature of the resin storage chamber is 2004500C.
The temperature of the chamber for compression molding can be freely set between 100°C and 450°C.

Further, the molding operation may be performed manually using heat-resistant gloves or the like, or may be performed automatically using a combination of an appropriate manufacturing machine and a control circuit (not shown).

For example, a lower flask containing a thermoplastic synthetic resin is stored in the resin storage chamber, an upper flask with a built-in artificial tooth is attached to a compression molding machine in the molding chamber, and the lower flask is stored while the resin is heated and softened. In some cases, the flask is taken out of the chamber and placed in a molding machine, and the upper and lower flasks are combined and compression molded. Since the present invention is a manufacturing method as described above, it exhibits the following effects.

Firstly, a highly accurate denture base with no polymerization shrinkage can be obtained by molding thermoplastic synthetic resin that has been softened by heating. This means that it can be manufactured using inexpensive equipment.

Secondly, since it is compression molding, it is possible to visually check the extent to which the resin protrudes from the flask during compression, making it possible to mold the resin in every corner. It is especially important to be able to visually confirm dental denture bases, as there is only one mold that fits the order and failure is not an option.
Thirdly, since thermoplastic synthetic resin that has been softened by heating is put into a flask that has already been heated in a constant temperature state and then compression molded, the operation is simple, and there is no polymerization time, so it can be manufactured quickly.

Fourthly, it is possible to use not only acrylic resin but also many types of thermoplastic resins, which provides excellent effects.

Incidentally, Utility Model Registration Publication No. 3501 of 1932 proposes a molding device for a rubber bed, which was commonly used in dentistry at that time. In this method, the rubber plastic material is set in upper and lower flasks without heating, that is, at room temperature, and heated and molded in this state. However, with such a molding machine, it is difficult to manufacture a denture base made of thermoplastic synthetic resin, which has been used in recent years and requires a predetermined temperature setting, and it is impossible to put it into practice.

In the present invention, the upper and lower flasks and the thermoplastic synthetic resin are set in advance to respective predetermined heating temperatures, and the thermoplastic synthetic resin is heated and softened at a predetermined temperature of 100 to 450°C, which is placed on the divided lower flask at a predetermined temperature. Since the upper and lower flasks are compression molded together, denture bases can be produced with good accuracy in a short time and without failure using a simple machine.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of the present invention. 2... Flask, 3... Thermoplastic synthetic resin, 4... Container.

Claims (1)

[Claims] 1. The upper and lower flasks and the thermoplastic synthetic resin are set in advance to their respective predetermined heating temperatures, and the thermoplastic synthetic resin heated and softened at a predetermined temperature of 100 to 450 ° C. is placed on the divided lower flask at a predetermined temperature. A denture base manufacturing method characterized by compression molding upper and lower flasks together.