JPH0322781B2 - - 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. <Conventional technology> Conventionally, in order to provide stable and strong support to the alveolar ridge and prevent wobbling during mastication, involuntary tenderness, and falling off, rubber elastic or flexible lining materials have been attached to the denture base body. It is known that it forms on the alveolar ridge contact surface. As the material for such backing material, soft fluororesin is used (Japanese Patent Application Laid-Open No. 1983-1999).
No. 21919), those using collagen (Special Publication No. 1987),
-50498), those using silicone rubber (Japanese Patent Application Laid-Open No. 58-54946), those using natural rubber and isoprene polymer (Japanese Patent Application Laid-open No. 55-26923), styrene,
There is one that uses a butadiene-based thermoplastic elastomer (Utility Model Application Publication No. 101622/1983). <Problems to be Solved by the Invention> When the above-mentioned materials are used as the lining material, the following problems occur. 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 was made in view of these circumstances, and uses a new thermoplastic elastomer as a lining material and synthesizes an adhesive most suitable for this lining material, thereby making it possible to create special machines. The purpose of the present invention is to realize a method for manufacturing a denture base that does not require molding and is easy to mold. <Means for Solving the Problems> The method for manufacturing a denture base according to the present invention includes the following steps. The step of forming a spacer with a shape matching the lining material on the plaster jaw model in the first flask, mounding up wax in the shape of the denture base body on the spacer, and arranging the artificial teeth on the wax; A step of stacking a second flask on the first flask and filling it with fluidized gypsum and solidifying it; a step of dividing the pair of flasks and removing only the wax; a first flask having the spacer or the like; A rice cake-like mixture obtained by kneading PMMA powder into liquid methyl methacrylate (hereinafter referred to as MMA) monomer is placed between the third flask, which has a jaw model that is almost the same as the one above, and has a rubber layer formed thereon, and the second flask.
A step of sandwiching PMMA, heating, pressing and polymerizing; dividing the above pair of flasks and applying a copolymer containing at least polyethylene and MMA or polypropylene and MMA to a predetermined exposed surface of the denture base body formed by polymerizing and curing the above PMMA. applying and drying an adhesive containing a copolymer containing a copolymer; removing the spacer on the jaw model in the first flask; Or, in a softened or melted state, the lining material is made of an olefinic thermoplastic elastomer containing polypropylene or a mixed material of the olefinic thermoplastic elastomer and a thermoplastic elastomer made of a styrene-ethylene-butylene (hereinafter referred to as SEBS) copolymer. Pinch: A process of clamping the flasks together. (B) Complete denture Figure 1 shows an example of the case where it is adopted as a mandibular complete denture 1. In the figure, 2 is the denture base body made of PMMA resin, and 3 is the surface of the denture base body 2 facing the alveolar ridge mucosal surface. 4. Rubber elastic lining material adhered to the entire surface with a thickness of approximately 0.5 mm to 1.5 mm; 4.
4... are artificial teeth fixed to the denture base main body 2. Here, the following materials are used for the lining material 3 and its adhesive. (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 such as 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 scale (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, thermoplastic elastomer made of SEBS copolymer is blended with olefinic thermoplastic elastomer to improve temperature control. Furthermore, this SEBS-based thermoplastic elastomer has better shape retention against temperature changes than the olefin-based thermoplastic elastomer, so by mixing the two, the overall durability is improved. This kind of SEBS-based thermoplastic elastomer is obtained by hydrogenating a styrene-butadiene-based thermoplastic elastomer, and for example, Lavalon (registered trademark) manufactured by Mitsubishi Yuka 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 thermoplastic elastomer reduces the adhesive strength to the denture base body, the mixing ratio actually needs to be about 75% or less. 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. The hardness of the lining material 3 is preferably at least two types, hard and soft, depending on the location where it is used, with a hard one having a hardness of about 70 and a soft one having a hardness of about 50.
It is sufficient to set it to a certain degree. (C) Adhesive The adhesive for bonding the lining material 3 to the denture base main body 2 made of PMMA contains at least a copolymer containing polyethylene and MMA or a copolymer containing polypropylene and MMA. One manufacturing method will be described in detail below. 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 4 hours of polymerization, 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 carried out using a Soxhlet extractor with ethyl acetate. Extract for 8 hours,
PMMA and MMA were dissolved and removed. As a result of analyzing the graft copolymer thus produced using infrared spectroscopy and other analytical methods,
It was confirmed that the desired molecular structure was obtained. The following table shows the degree of polymerization, degree of grafting, and grafting efficiency of three types of polyethylene-MMA graft copolymer products A, B, and C with varying BPO concentrations.

[Table] The unit of BPO concentration is ×10 ^-3 mol/, 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, chloride-based 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. The melting point of copolymer product B was thereby determined to be approximately 118°C. This means that when the adhesive made of copolymer product B is applied to the lining material and the cake-like PMMA is pressed and polymerized and solidified by heating to about 100°C to 130°C, the copolymer product This means that the adhesive is dissolved, and it is presumed that this causes the generation of adhesive function and the improvement of its action. In fact, it was confirmed that when the bonding time is increased, the bonding function occurs even at about 100°C due to a relaxation phenomenon. Polypropylene is used in place 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 made of ortho-xylene. A good adhesive was also obtained when dissolved in a solvent. Furthermore, MMA was graft-polymerized to the above-mentioned TAFMER (registered trademark) A4085 (product number), which is an olefin-based thermoplastic elastomer, as a backbone polymer under the same conditions as the above-mentioned polymerization method (conditions for product B). An adhesive can also be prepared by producing a copolymer of an olefinic thermoplastic elastomer and MMA and dissolving this in a solvent consisting of 1.1.1 trichloroethane. Graft copolymer of polyethylene and MMA,
The graft copolymer of polypropylene and MMA was used as an adhesive material because of its compatibility with polyethylene or polypropylene contained in the olefinic thermoplastic elastomer and
This takes into consideration compatibility with PMMA denture bases. Therefore, the above copolymer is not limited to a copolymer of polyethylene or polypropylene and MMA, but also a copolymer of polyethylene and polypropylene.
It may be a terpolymer of MMA, or a copolymer of polyethylene or polypropylene and another substance such as vinyl acetate may be further copolymerized with MMA. (d) Method for manufacturing a denture base Figure 4 shows a method for manufacturing a denture base using the lining material and adhesive according to the present invention in order of steps, and will be explained below with reference to the figures. (A) A jaw model 5 obtained by taking an impression from a patient is formed using plaster 7 in a first flask 6. A hardening plastic material such as a slow polymerizing dental resin, a photopolymerizing resin material, a thermosetting resin material such as plastic clay is applied to the lining material formation site on the jaw model 5 (the entire surface of the complete denture shown in FIG. 1). A spacer 8 having a thickness of, for example, about 1 mm is formed. Since this spacer 8 corresponds to the part where the posterior lining material is to be formed, it is treated, for example, by making the surface that contacts the thin part of the gum thicker. This spacer 8 is molded while it is in a plastic state and then hardened. (B) Wax 9 is raised in the shape of a denture base on jaw model 5 including spacers 8, and artificial teeth 4 are arranged on this. Such work is usually performed by dentists. (C) Cut off the peripheral portion of the denture base formed with wax 9 over a predetermined width. Since a lining material will ultimately be formed in the cut portions 10, 10, the above-mentioned cutting process is performed while considering the portions that are preferably used as the lining material. (D) The cut portion 10 of the wax 9 is filled with the same material as the spacer 8, such as thermosetting plastic clay. This filling portion is formed to be relatively thick in order to clearly define the boundary line with the denture base body. Subsequently, plasters 11, 11 are poured around the filled portion of the spacer 8 to fix the spacer 8. (E) After applying a separating agent to the surface of the plaster mold of the first flask 6, the second flask 12 is placed on top of this, and the plaster 13 in a fluid state is poured into it. (F) After the plaster 13 has solidified, the first and second flasks 6 and 12 are placed in a stacked state in a container 14 and immersed in hot water at about 100° C. for about 5 minutes. This melts the wax 9 and at the same time hardens the spacer 8. (G) This pair of flasks 6 and 12 are divided,
The wax 9 is removed by washing with hot water. (H) Flexible mold release films 15, 15 such as polyethylene films are placed on the surface of each plaster mold of flasks 6, 12, and this film 15,
The denture base space is filled with a plastic material 16 such as clay for 15 minutes. The plastic material 16 must at least maintain its shape after molding. (I) The flasks 6 and 12 are pressed together, and the plastic material 16 is molded into a shape that matches the denture base body. (J) Separate the flasks 6 and 12, place the molded plastic material 16 thereon, turn the flask 12 upside down, apply two-component silicone rubber to the surface of the plastic material 16, and harden it to a thickness of approximately 1 mm or more. A rubber thickness 17 having a thickness of 2 mm is formed. Subsequently, a third flask 18 is placed on top of the flask 12, and fluidized plaster 19 is poured into the flask 12 to form a jaw model substantially identical to the first flask 6. The rubber layer 17 is used as a mold when molding the posterior denture base body, and if an undercut exists in the denture base body, the elasticity of the rubber layer 17 facilitates its removal. (K) After the plaster 19 has hardened, the flasks 12 and 18 are divided and the plasticizer 16 is applied to the mold release films 15 and 1.
Remove along with 5. (L) The denture base space 20 is filled with a rice cake-like PMMA 21 formed by adding a polymerization initiator to liquid MMA monomer and kneading PMMA powder. (M) The flasks 12 and 18 are clamped together, placed in a container 22, and placed in steam at about 100°C to 130°C to polymerize and harden the cake-like PMMA to form the denture base body 2. (N) Separate the flasks 12 and 18, apply adhesive 23 to the exposed surface of the denture base body 2, and dry. Remove the spacer 8 from the flask 6 in step (I). (O) Place the lining material 3 in the recess of the denture base body 2 at approximately 120°C.
The material is heated and softened at a temperature of . This temperature needs to satisfy both the molding temperature of the lining material 3 and the softening temperature of the adhesive 23. (P) Then, tighten flasks 6 and 12. For filling the lining material 3, a press molding method or an injection molding method can be used. However, the molding temperature of the lining material 3 is
Since it can be formed at a temperature of about 120°C, it can be heated and molded in hot water, steam, or edible oil, thereby eliminating the need for a special press molding machine or injection molding machine. (Q) After cooling the flasks 6 and 12, divide them, break the plaster, and take out the denture 24. Thereafter, the lining material 3 is subjected to processing such as grinding and correction, and the denture base main body 2 is polished to complete the denture 24. Note that in the above steps, if the jaw model 5 does not have an undercut, steps (H) to (J) can be omitted. That is, the spacer 8 is left in the plaster mold of the flask 6 in step (G), and this is used as a mold for the denture base body. In such a case, the first flask 6 is used instead of the third flask 18 in steps (K) to (M). (E) Partial dentures and attachments The manufacturing method described above is also useful in manufacturing partial dentures or dentures with attachments. FIGS. 5A and 5B show a partial denture 25, in which the lining material 3 has protrusions 26, 26 at both ends, and these protrusions 27, 27 are connected to adjacent natural teeth, etc.
It comes into contact with the undercut of the denture and maintains the denture. 28 is the alveolar ridge. FIG. 6 shows an example of the stud attachment 29, in which 30 is a metal stud fixed to a tooth root 31, 3 is a lining material, and the attachment female 32 is a metal stud fixed to a tooth root 31.
It is formed at the same time when molding. 33 is a gingival part. Fig. 7 shows an example adopted in the Darbo attachment 34, and 35 is a metal mail.
It is fixed to the maintenance teeth 27. 3 is a backing material and a female mail 36 that holds the mail 35;
is integrally molded with the lining material 3 at the same time. A metal ring 37 fixed to the artificial tooth 4 extends from the female mail 36, and the mail 35 engages with this metal ring 37. Reference numeral 26 denotes two protrusions formed on the lining material 3, and two protrusions are provided so as to abut the undercuts of the retaining teeth 27 from the left and right sides of the attachment 34. <Effects of the Invention> According to the present invention, the following effects can be obtained. 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. as at least polyethylene and MMA
Copolymer or polypropylene containing
By using an adhesive containing a copolymer containing MMA, the lining material can be firmly adhered to the denture base body made of PMMA. The lining material softens at temperatures above about 70°C, while the adhesive also softens at temperatures above about 100°C.
Molding and adhesion are possible by heating in hot water, steam, or edible oil. 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 diseased case, and the problems of being too hard or too soft, which have been seen in conventional 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. In addition, 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 wettability to saliva, resistance to oral bacteria contamination, erosion, food coloring, 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 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, and on the contrary, it absorbs the impact applied to the denture, reducing the burden on the alveolar ridge. be able to.

[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; FIGS. 4A to Q are cross-sectional views showing the manufacturing method according to the embodiment of the present invention in the order of steps;
FIG. 5A is a top view showing one shape of a partial denture that can be manufactured by the same manufacturing method, and FIG. 5B
5A is a cross-sectional view of FIG. 5A, FIG. 6 is a cross-sectional view showing another shape, and FIG. 7 is a cross-sectional view showing still another shape. 1... Complete denture, 2... Denture base body, 3... Lining material, 4... Artificial tooth.

Claims (1)

[Claims] 1. A spacer having a shape matching the lining material is formed on the plaster jaw model in a first flask, wax is raised on the spacer in the shape of the denture base body, and an artificial A step of arranging the teeth; A step of stacking a second flask on the first flask and filling it with fluidized gypsum and solidifying it; A step of dividing the pair of flasks and removing only the wax; A step of removing the spacer. A mixture obtained by kneading polymethyl methacrylate powder into a liquid methyl methacrylate monomer between the first flask having the same jaw model or a third flask having a rubber layer formed thereon and the second flask. A step of sandwiching the sticky polymethyl methacrylate and polymerizing it by heating and pressing; dividing the pair of flasks and applying at least polyethylene and methyl methacrylate to a predetermined exposed surface of the denture base main body formed by polymerizing and curing the polymethyl methacrylate. or a copolymer containing polypropylene and methyl methacrylate; and drying; removing the spacer on the jaw model in the first flask; The flask is softened or lined with a lining material made of an olefinic thermoplastic elastomer containing at least polyethylene or polypropylene as a hard segment, or a mixed material of the olefinic thermoplastic elastomer and a thermoplastic elastomer consisting of a styrene-ethylene-butylene copolymer. A method for manufacturing a denture base having an elastic lining material, which includes the step of clamping the flasks together in a molten state.