JPS60227750A - Fabrication of denture bed - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a denture base by injection molding or extrusion molding of a thermoplastic resin.

Conventionally, the method of manufacturing denture bases by compression molding has been to mold a mixture of acrylic monomer and polymer, then
Methods of polymerizing at room temperature or by heating are known, but in recent years denture bases using thermoplastic resins with excellent heat resistance and strength have been developed and are attracting attention.

Injection molding method (Japanese Patent Publication No. 57-2028) and extrusion molding method are already known as methods for manufacturing denture bases using thermoplastic resin.

In both cases, melted and softened thermal 0T plastic resin is injected or extruded into a flask containing artificial teeth and shaped.
This method is to take it out after cooling and assimilation.

As a result of research, the present inventors found that in the injection molding method and extrusion molding method described above, when no treatment is applied to the artificial tooth built in the flask, as in the injection molding or extrusion molding that is usually performed, It has been found that this method has the drawback that the fusion between the artificial tooth and the resin forming the denture base is not sufficient, and the artificial tooth easily detaches from the denture base.

The object of the present invention is to provide a method that improves the above-mentioned drawbacks and provides good results, ie, a denture base in which the artificial tooth is firmly implanted and has good filling properties.

In a method of manufacturing a denture base by injecting or extruding a thermoplastic resin into a flask containing an artificial tooth, and taking it out after cooling and solidifying, the root of the artificial tooth is preheated to 80 to 800 ° C. It's about doing.

The thermoplastic resin used as the denture base in the present invention does not undergo thermal deterioration through the molding method, has an appropriate viscosity, has good infill formability, and has a color similar to tooth β. It is required that the resin be colorable, have appropriate rigidity and moisture resistance, and be tough enough not to cause stress cracks during use.

Therefore, polystyrene, polymethyl methacrylate, polymethyl pentene-1, transparent nylon, polycarbonate, polyarylate, polyester carbonate,
Polyethylene terephthalate, transparent ABS, polysulfone resins, etc. are used, but polysulfone resins such as polysulfone and polyethersulfone are particularly moisture resistant.
It has excellent rigidity, stress cracking resistance, etc.
preferable. The polysulfone resin used as a preferred embodiment of 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, a UCC-made policer with the structure, 7 Ude 1”
ICI made port +) x -7t, S/l/ * 7V
ictrex".

The artificial teeth used in the present invention include resin teeth made of acrylic resin, porcelain teeth, polycarbonate teeth, polyarylate teeth, polysulfone teeth, etc., which are commonly used as artificial teeth in the past.

As a material for artificial teeth, it is a resin that can be colored to resemble natural teeth, has appropriate rigidity, wear resistance, and moisture resistance, and is tough enough to prevent stress cracks during use. This is required.

Therefore, in addition to the above-mentioned artificial teeth, artificial teeth made of polystyrene, polymethylpentene-1, polyamide, polyester carbonate, polyethylene terephthalate, transparent ABS, polyether sulfone, etc., and compositions containing these resins and appropriate reinforcing agents are used. Artificial teeth are available. When a human tooth made of a material having the same or similar structure or properties as the thermoplastic resin for denture bases is used, the adhesion between the artificial teeth and the denture base is better, and is therefore preferable.

The method of incorporating the artificial tooth into the flask is not particularly limited.

A commonly used method is to place a wax denture base model with artificial teeth in it in a flask, and then pour gypsum or silicone into it and harden it. After the plaster or the like hardens, a method is applied in which the wax is heated and softened by a proper method and then flowed out.

Any method can be used to preheat the root of the artificial tooth built into the flask, such as heating only a predetermined part of the artificial tooth locally with hot air or infrared rays, or heating with a burner. be. If only the part that will be implanted into the denture base, that is, the root of the artificial tooth, is heated to a state close to softening, and the tip of the artificial tooth is injection molded or extruded without changing its shape, it will be more similar to the artificial tooth. A method that locally heats only the root of the artificial tooth is a method that allows for a comfortable denture (a combination of an artificial tooth and a denture base) with good adhesion of the denture base and no change in the shape of the artificial tooth. Applicable.

A preheating temperature of 80-3000 is required for the root of the artificial tooth. If the temperature is less than 80°C, the preheating effect will be poor and the adhesion between the artificial tooth and the denture base will be insufficient. Moreover, if the temperature exceeds 800°C, the strength of the artificial tooth will be significantly reduced due to softening deformation, thermal deterioration, residual strain due to heat, etc., which is not preferable. Further, a temperature of 100 to 270°C is preferable because there is no change in the shape or strength of the artificial tooth and higher adhesion with the denture base is obtained.

Hereinafter, the present invention will be specifically explained with reference to examples, but these are merely illustrative of preferred embodiments and are not limited to the scope of the examples.

Example 1 According to the artificial tooth fracture test method described in Japanese Industrial Standard JIST-6511, as shown in Figure 1, polyether sulfone (planted in a paraffin wax model at an angle of 45° with the paraffin wax model made by ICI) After embedding plaster in a flask, a bruise was formed and a plaster mold was formed.

The flask and plaster mold were divided into two parts, one with the artificial tooth built in and one without, and after preheating the root of the artificial tooth made of polyethersulfone in the flask by blowing hot air at 220°C for 2 minutes, Combined with the divided flasks, the cylinder temperature is 360℃ and the injection pressure is 1500Kf/d.
, injection speed 250 s+aA/) (molding machine: Sumitomo-Nestal P40/25), a molten resin of polyethersulfone colored like gums was injected into the flask.

After cooling, the flask was divided and molded articles for artificial tooth fracture testing were taken out.

As shown in FIG. 1, the resin bed part 2 is fixed with a holder 8, and the other artificial gear end part 1' is fixed with a predetermined metal fitting 4 at a load speed of 12.
A fracture test was conducted at Kgf/min.

The fracture strength was 27 Kgf, which was a sufficiently high value to cause no practical problems.

Comparative Example 1 An artificial tooth made of polyethersulfone was molded under the same conditions as Example 1 without preheating,
An artificial tooth fracture test was conducted.

The fracture strength was only 6 KffL, which was a low value that would pose a practical problem.

Comparative Example 2 Everything was the same as Example 1 except that the artificial tooth made of polyether sulfone was preheated by blowing hot air at 880°C for 2 minutes.
When molding was performed under the same conditions as above, the artificial tooth was greatly deformed and a good molded product could not be obtained.

Example 2 Heating a flask in which a wax model of a denture base in which an artificial tooth formed from polysulfone (UCCIjlUdegOP1700) was implanted was embedded.
The flask and plaster mold were divided into two parts, one containing the artificial tooth and the other without, and the root of the artificial tooth formed from polysulfone inside the flask. After preheating by blowing hot air at 190℃ for 2 minutes, the divided flasks were put together and the cylinder temperature was 840℃, the injection pressure was 1800Kg/d, and the injection speed was 200/sec (molding machine: Sumitomo Nestal P40/ 2
5) Under the conditions described above, a molten polysulfone resin colored to resemble gums was injected into the flask.

After cooling, the flask was divided and the denture base was removed.

A denture base was obtained in which the artificial tooth was firmly planted without easily coming off even when the artificial tooth was strongly pressed.

Comparative Example 8 An artificial tooth made of polysulfone was molded under the same conditions as in Example 2 without preheating, and a denture base was molded, but the artificial tooth was removed from the a-tooth base by just being lightly pressed.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of the artificial tooth fracture test. l......Artificial tooth ll...Incisal end part 1 of artificial tooth//......Incisal end part 2 of artificial tooth...・
...Resin floor part 3 ...... Holder 4 ...... Artificial tooth tension fitting Fig. 1

Claims (1)

[Claims] In a method of producing a denture base by injecting or extruding a melted and softened thermoplastic resin into a flask containing an artificial tooth, and taking it out after cooling and solidifying, the root of the artificial tooth is A method characterized by preheating to 800°C.