JPH0256101B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for manufacturing a denture base having an elastic lining material, and in particular to a method for manufacturing a denture base having an elastic lining material that has a shape that matches the shape of the alveolar ridge. The present invention relates to a method for manufacturing a denture base to which a dental covering is bonded. <Prior Art> Normally, the alveolar ridge is deformed due to recession of the alveolar bone. Therefore, even if a denture is made to match the shape of the alveolar ridge, it must be remade or the shape modified every few years. On the other hand, conventionally, in order to provide stable and strong support to the alveolar ridge and to prevent wobbling during mastication, unintentional tenderness, and falling off, rubber elastic or flexible lining materials have been used to provide stable and strong support to the alveolar ridge of the denture base body. It is known that it is formed on the contact surface. Materials for such lining materials include those using soft fluorine resin (Japanese Patent Application Laid-open No. 55-21919), collagen (Japanese Patent Publication No. 57-50498), and silicone rubber (Japanese Patent Application Laid-Open No. 57-50498). No. 58-54964), those using natural rubber and isoprene polymer (Japanese Patent Application Laid-Open No. 55-26923),
There is one that uses a styrene-butadiene thermoplastic elastomer (Japanese Patent Application Laid-open No. 101622/1983). <Problems to be solved by the invention> Polymethyl methacrylate (hereinafter referred to as PMMA) resin, which is widely used as the material for the denture base body, has poor adhesion to the lining material, and it is difficult to find a lining that can be bonded to it for a long period of time. Even if the number of covering materials is small and has good adhesive properties, it is necessary to satisfy conditions such as the need to utilize the polymerization effect of PMMA. Therefore, it is extremely difficult to bond a new lining material to a denture that has been made, and it has not been put to practical use yet. Further, when the above-mentioned materials are used as the lining material, there are the following problems. In the case of soft resin, its rubber elasticity is limited, making it unsuitable for maintaining attachments, and when it is deformed by local pressing force, it does not have the same restoring force as rubber. If a thin sheet is pressed against the mucosal surface of the denture base, it is difficult to fill the undercut portion of the retaining tooth, and sufficient retaining force cannot be obtained. Since silicone rubber is a vulcanized rubber, it is difficult to modify it once it has been vulcanized and molded. The present invention solves these problems by using a new thermoplastic elastomer as the lining material and by synthesizing an adhesive that is most suitable for this lining material. , we have realized a method for manufacturing a denture base that allows bonding of the lining material even on a completed denture. <Means for Solving the Problems> The method for manufacturing a denture base having an elastic lining material according to the present invention includes the following steps. A denture base made of PMMA resin, polycarbonate resin, polysulfone resin, or polyethersulfone resin, with artificial teeth arranged on its top. Impression material is piled up on the mucosal contact surface and pressed against the alveolar ridge in the patient's mouth to take an impression. Process: Pour plaster into the recesses of the impression material formed by pressing the alveolar ridge, and after the plaster hardens, fix it in one flask using plaster; Overlap the above flask with another flask and pour the plaster into it. Pouring step: dividing the flask, removing the impression material,
Applying and drying an adhesive containing at least a copolymer containing polyethylene or a copolymer containing polypropylene directly to the alveolar ridge mucosal contact surface of the denture base or on a new surface obtained by thinly removing that surface; The surface of the plaster mold obtained by removing the impression material is coated with an olefinic thermoplastic elastomer containing at least polyethylene or polypropylene as a hard segment, or a thermoplastic elastomer consisting of the olefinic thermoplastic elastomer and a styrene-ethylene-butylene copolymer. A step of heating the lining material made of a mixed material to soften or melt it; a step of stacking and pressing the two flasks together, molding the lining material, and simultaneously adhering the lining material to the denture base; . <Example> (a) Complete denture Figure 1 shows an example of a mandibular complete denture 1 manufactured in an example of the present invention, and 2 in the figure shows PMMA resin,
The denture base body 3 is made of polycarbonate resin, polysulfone resin, or polyethersulfone resin, and 3 is a rubber elastic material bonded to the surface of the denture base body 2 that contacts the alveolar ridge mucosal surface with a thickness of about 0.5 mm to 1.5 mm. A lining material having 4, 4...
is an artificial tooth fixed to the denture base body 2. Here, the following materials are used for the lining material 3 and its adhesive surface. (b) Backing material The 3rd material of the lining material is an olefinic thermoplastic elastomer containing at least polyethylene or polypropylene as a hard segment, or this olefinic thermoplastic elastomer.
A mixed material of thermoplastic elastomer consisting of SEBS copolymer is used. Olefin thermoplastic elastomers consist of hard segments made of polyethylene or polypropylene and soft segments made of homopolymers or copolymers of butene, propylene, butadiene, etc.
It has a softening temperature of 100°C or less and a wide range of hardness from about 20 to 90 on the JIS hardness (hereinafter simply referred to as hardness). As this type of olefin thermoplastic elastomer, Tafmer (registered trademark) manufactured by Mitsui Petrochemicals Co., Ltd. is suitable. This thermoplastic elastomer is an α-olefin thermoplastic elastomer, and there are those that contain either polyethylene or polypropylene alone as a hard segment, and those that contain both polyethylene and polypropylene, and their hardness is as follows:
From about 20 to over 90. By blending these, the hardness can be adjusted within the usable range of about 40 to 80. The above olefin thermoplastic elastomer is
Since it begins to soften at around 70°C, a thermoplastic elastomer made of SEBS copolymer is blended with an olefinic thermoplastic elastomer to improve its temperature characteristics. Furthermore, this SEBS thermoplastic elastomer has better shape retention against temperature changes than the olefin thermoplastic elastomer, so by mixing the two, the overall durability is improved. This kind of SEBS-based thermoplastic elastomer is obtained by hydrogenating an ethylene-butylene-based thermoplastic elastomer, and for example, Lavalon (registered trademark) manufactured by Mitsubishi Oil Chemical Corporation can be used. Second
The diagram shows olefinic thermoplastic elastomer and
The hardness-temperature characteristics are shown when the mixing ratio of SEBS-based thermoplastic elastomer is changed. In the figure, the numerator indicates the proportion of the olefin thermoplastic elastomer, and the denominator indicates the proportion of the SEBS thermoplastic elastomer. As is clear from the figure, when the mixing ratio of SEBS thermoplastic elastomer is increased, approximately
It can be seen that softening from around 70°C is suppressed.
Furthermore, if the SEBS thermoplastic elastomers have different hardnesses, the hardness will change upon mixing, so the hardness can be adjusted by this. However, since an increase in the SEBS-based thermoplastic elastomer lowers the adhesive strength to the denture base body, the mixing ratio actually needs to be about 75%. As mentioned above, the olefin-based thermoplastic elastomer itself begins to soften rapidly at around 70°C, but most of the lining material is between the denture base body and the alveolar ridge mucosal surface and is shielded from the outside. This does not heat up to around 70 degrees Celsius, and there is a possibility that the area around the lining material that is exposed in the oral cavity will reach this temperature instantaneously, but the temperature will rise enough to cause it to soften and deform. is not retained, and for practical purposes, the olefin thermoplastic elastomer alone can be used. It is possible to mold the lining material 3 at a temperature of approximately 70° C. or higher. Therefore, it can be heated in hot water, steam, higher alcohol, or edible oil. In particular, edible oil can be heated up to about 200℃.
When heated to such a temperature, the fluidity of the lining material 3 is further improved. Therefore, it is also possible to put it in a tube or the like to form a lump and heat it. As for the hardness of the lining material 3, it is preferable that there are at least two kinds of hardness depending on the place of use, hardness being about 70 and softness being about 50. (c) Adhesive The adhesive for bonding the lining material 3 to the denture base main body 2 contained at least a copolymer containing polyethylene or a copolymer containing polypropylene, and was produced by the following method. Polyethylene was heated and dissolved in toluene in a polymerization reactor, a predetermined amount of MMA and benzoyl peroxide (hereinafter referred to as BPO) as a radical polymerization initiator were added, and graft polymerization was performed at 70°C under a nitrogen atmosphere. After polymerization for 4 hours, the polymer solution was poured into a large amount of poor solvent (methanol in this example) to precipitate and separate the polymer. Separation of PMMA and MMA monomers was performed using a Soxhlet extractor with ethyl acetate. Extract for 8 hours,
PMMA and MMA were dissolved and removed. The thus-produced graft copolymer was analyzed using infrared spectroscopy and other analytical methods, and it was confirmed that the desired molecular structure was obtained. Here, MMA has a solubility parameter (sp value) similar to that of polycarbonate, polysulfone, and polyethersulfone, so
It is the most suitable material for such copolymers.
Here, the sp values of each material are MMA9.3 to 9.9, polycarbonate 9.8, polysulfone 9.9, and polyethersulfone 9.7 to 9.9. The following table shows the degree of polymerization, degree of grafting, and grafting efficiency of three polyethylene-MMA graft copolymer products A, B, and C with varying BPO concentrations.

[Table] The unit of BPO concentration is ×10mol ^-3 /, and the degree of grafting and grafting efficiency are values calculated using the following formula. Grafting degree % = Grafted monomer amount / Stem polymer amount × 100 Grafting efficiency % = Grafted monomer amount / Polymerized monomer amount × 100 The graft copolymer obtained as described above was added to 1.1.1. trichloroethane. It was dissolved to form a liquid adhesive. 1.1.1. Trichloroethane used as a solvent is suitable as this kind of solvent because it is non-toxic and easily evaporates with a boiling point of 74.1°C. In addition, chlorinated organic solvents such as chloroform, toluene, xylene, ethers, etc. can be used as the solvent. FIG. 3 shows the analysis results of copolymer product B by a differential thermal analyzer. Accordingly, the melting point of copolymer product B was determined to be approximately 118 degrees. This means that when an adhesive made of copolymer product B is applied to the denture base body and a lining material that has been softened or melted by heating to about 120°C is pressed against it, the polymerization product softens or melts. It means to dissolve, thereby generating an adhesive function and improving its effect. In fact, if the bonding time is increased, the bonding function will occur even at about 110°C due to relaxation phenomenon, so the bonding temperature of the lining material can be set to about 100°C or higher. In addition, polypropylene is used instead of polyethylene, and MMA is polymerized thereto under the same conditions as in the polymerization method described above (conditions for product B) to produce a graft copolymer of polypropylene and MMA, which is then combined with ortho-xylene. A good adhesive was also obtained when dissolved in a higher solvent. Furthermore, the above-mentioned TAFMER (registered trademark) A4085, which is an olefinic thermoplastic elastomer,
Using (product number) as a backbone polymer, MMA is graft-polymerized to this under the same conditions as the polymerization method described above (conditions for product B) to produce a copolymer of α-olefin thermoplastic elastomer and MMA. Good adhesive action was also obtained when the adhesive was prepared by dissolving it in ortho-xylene. The graft copolymers of polyethylene and MMA and graft copolymers of polypropylene and MMA were used as adhesive materials because of their compatibility with the polyethylene or polypropylene contained in the olefinic thermoplastic elastomer and their compatibility with the denture base body. This takes into account solubility. Therefore, the above copolymer is not limited to a copolymer of polyethylene or polypropylene and MMA, but may also be a terpolymer of polyethylene, polypropylene and MMA, or a copolymer of polyethylene or polypropylene and other substances such as vinyl acetate. MMA may be further copolymerized with the copolymer. (d) Method of adhering lining material FIG. 4 shows a method of adhering an elastic lining material to a denture base main body according to an embodiment of the present invention in the order of steps, and will be explained below with reference to the figures. (A) After completion of the denture 5, the lining material on the inner surface of the denture base body 2 is to be bonded, or when the inner surface of the denture base body 2 no longer matches the shape of the alveolar ridge due to long-term use, the shape of the denture 5 must be corrected. At the same time, the inner surface of the denture base main body 2 to which the lining material is to be bonded is filled with an impression material 6 made of silicone impression material or alginic acid impression material. (B) The denture 5 treated as described above is placed on the intraoral alveolar ridge 7 of the patient, and an impression is taken of the occlusion (indicated by the arrow in the figure) with the opposing teeth 8. (C) Excess impression material 6 is removed, and plaster 9 is poured onto the inner surface of impression material 6 and solidified. (D) The denture 5 is placed in a flask 10 together with plaster 9 and fixed with plaster 11. (E) After applying a mold release agent to the surface of the plaster 11, the flask 10 is stacked with another flask 12, and the plaster 13 is poured into it to embed the denture 5. (F) After solidification of plaster 13, the above pair of flasks 1
0 and 12 are divided and the impression material 6 is removed. After the inner surface of the denture base body 2 is thinly scraped to expose a new surface, an adhesive 14 is applied to this surface and dried. At the same time, the lining material 3 is placed on the surface of the plaster 9 jaw model in a heated, softened or melted state. (G) Overlap flasks 10 and 12 and press them together. In this state, put it in a heating pot and heat it to about 100℃.
Leave in a steam atmosphere at 130°C for about 10 minutes, then cool. This is to ensure more complete adhesion between the lining material 3 and the denture base main body 2. (H) After cooling the flasks 10 and 12, the plaster is destroyed and the denture 5 is taken out. Thereafter, the lining material 3 is subjected to processing such as grinding correction, and the denture base body 2
is polished, and the denture 5 is completed. In the above embodiment, the case where the lining material 3 was bonded to the denture base body 2 made of PMMA was explained.
In addition to PMMA resin, polycarbonate resin, polysulfone resin, and polyethersulfone resin were used to form two denture base bodies by injection molding, and the lining material 3 was adhered to this using the adhesive 14 described above. In both cases, strong adhesive strength was obtained. <Effects of the Invention> According to the present invention, the following effects can be obtained. Since the lining material is bonded after the denture base body is formed, the lining material can be bonded to the alveolar ridge mucosal contact surface of the old denture by scraping off a thin layer. Further, even in a denture having a lining material, the old lining material can be scraped off and a new lining material can be bonded to the inner surface of the denture base main body. This is because many commercially available products allow the lining material to be bonded only when the denture base polymerizes, and as the dentures age, they no longer fit the alveolar ridge, and the dentures must be replaced every few years. Considering that the present situation is such that it does not occur, the manufacturing method according to the present invention can be said to be extremely useful. That is, according to the present invention, a lining material can be easily bonded to an old denture that does not have a lining material, and even if the shape of the denture base and lining material needs to be modified, the old denture can be easily bonded. It can be used as is. As the lining material, an olefinic thermoplastic elastomer containing at least polyethylene or polypropylene as a hard segment, or a mixed material of this olefinic thermoplastic elastomer and a thermoplastic elastomer consisting of a styrene-ethylene-butylene copolymer is used, and an adhesive is used. By using an adhesive containing at least a copolymer containing polyethylene or a copolymer containing polypropylene, the lining material can be firmly adhered to the denture base main body. The lining material softens at temperatures above about 70°C, and the adhesive also softens at temperatures above about 100°C, so it can be molded and bonded by heating in hot water, steam, or edible oil. becomes. Therefore, a lining material of any shape can be easily produced without using a special machine. Since the hardness of the lining material can be set arbitrarily, it can be set to the optimum hardness suited to the case, and the problems of being too hard or too soft, which have conventionally been seen in commercially available products, are solved. In other words, lining materials having partially different hardnesses can be used depending on the operating characteristics in the oral cavity. At this time, the interface between materials of different hardness is completely integrated and continuous. Further, when replenishing and correcting, if the lining material is softened and the same material is softened and pressure welded to it, the two can be easily welded, so the correction can be carried out arbitrarily. Since a thermoplastic elastomer containing at least polyethylene or polypropylene is used as a hard segment as the lining material, the properties of polyethylene or polypropylene provide suitable leakage to saliva, resistance to oral bacteria contamination, resistance to erosion, food coloring agents, etc. It is possible to take advantage of the difficulty of dyeing due to the dyeing process, and improve the properties as a lining material. The lining material does not permanently change its rubber elasticity and is firmly adhered to the denture base body, so it can maintain a stable attachment function with strong suction force even after long-term use. Since the lining material can be formed into any shape, it can be used not only as a lining material for complete dentures, but also to form attachments such as Dalboa attachments, studs, and attachments integrally and simultaneously. becomes possible. The above-mentioned female mail elastically supports and fixes the mail part using the rubber-like elasticity of the lining material, so there is no risk of its supporting function decreasing.On the contrary, it absorbs the impact applied to the denture, which reduces the burden placed on the alveolar ridge. can be reduced. Furthermore, by bringing the lining material into contact with an intraoral undercut such as a retaining tooth undercut, the retaining force of the denture can be strengthened.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a denture base according to an example of the present invention, FIG. 2 is a hardness-temperature characteristic curve diagram when the mixing ratio of olefin thermoplastic elastomer and SEBS thermoplastic elastomer is changed, and FIG. FIG. 3 is a characteristic diagram showing the measurement results of the copolymer product using a differential thermal analyzer, and FIGS. 4A to 4H are cross-sectional views showing the manufacturing method according to the present invention in the order of steps. 1... Complete denture, 2... Denture base body, 3... Lining material, 4... Artificial tooth, 14... Adhesive.

Claims (1)

[Scope of Claims] 1. Impressions are taken from a denture base body made of polymethyl methacrylate resin, polycarbonate resin, polysulfone resin, or polyethersulfone resin, on which artificial teeth are arranged, and plaster is applied to the inner surface of the impression material of the denture base body. pouring the plaster and fixing it in one flask after it hardens using plaster; stacking the flask on another flask and pouring plaster; dividing the flask and removing the impression material;
Applying and drying an adhesive containing at least a copolymer containing polyethylene or a copolymer containing polypropylene directly to the alveolar ridge mucosal contact surface of the denture base or on a new surface obtained by thinly removing that surface; The surface of the plaster mold obtained by removing the impression material is coated with an olefinic thermoplastic elastomer containing at least polyethylene or polypropylene as a hard segment, or a thermoplastic elastomer consisting of the olefinic thermoplastic elastomer and a styrene-ethylene-butylene copolymer. Step of placing a lining material made of a mixed material in a softened or molten state by heating; The above two flasks are stacked and pressed together, and the lining material is molded and at the same time the lining material is bonded to the denture base. A method for manufacturing a denture base having an elastic lining material, comprising the steps of: