JPH037376B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a thermoplastic resin denture base in which an internal crown on an abutment tooth is maintained by fitting into a recess in the denture base like a wedge. <Prior Art> Conventionally, as a prosthetic method for cases with remaining teeth, there is known a so-called "telescope" prosthetic method using crowns that fit together with a denture base using metal clasps and attachments. Telescopes have been used in prosthodontics for several decades. The name "telescope" comes from the fact that the cylindrical tubes glide around while fitting into each other to focus the lenses, often representing the attachment and detachment of the telescope crown. The telescoping system allows for a completely rigid connection of abutment and fixed dentures to the retaining teeth, yet can be removed whenever necessary. However, in the case of a telescope called a cylinder telescope, that is, the outer wall of the inner crown on the abutment tooth and the inner wall of the outer crown attached to the abutment tooth are almost parallel on all axis walls. In this case, the inner and outer caps are maintained only by frictional forces. Therefore, it is often experienced that cylinder telescopes do not have sufficient holding force or have a holding force that is unnecessarily strong. If a telescopic denture is too firmly fixed, it cannot be removed without the use of considerable force, which can easily cause acute damage to the periodontal tissues. Additionally, when there is play in the cylinder telescope, the retaining force is not sufficient and the dentures move significantly, sometimes causing the upper dentures to fall, and in the lower jaw to move the tongue and floor of the mouth to raise the dentures. Therefore, various telescopes have been studied and proposed as a method to overcome these drawbacks.
In other words, the inner crown is cone-shaped, which is closed toward the occlusal surface, and the inner and outer crowns contact each other in parallel only in the final process of installation, so-called conus krone, or a mixture of cylinder telescope and conus krone. For example, there are mixed type telescopes, in which the outer wall of the inner crown and the inner wall of the outer crown are formed in an oval shape and fit together, and irregular telescopes, in which the outer wall of the inner crown is irregularly shaped. It is becoming popular in countries such as West Germany. Compared to cylinder telescopes, these improved telescopes are installed and maintained by inserting the inner crown into the outer crown in a wedge-shaped manner, so they have a more appropriate retaining force and are easier to remove. Since they come into contact with each other from the moment they are separated from each other, they have the advantage that they can be easily removed without friction after the impact for removal. In these improved telescopes, the outer crown is formed to be slightly smaller than the inner crown, so when the outer crown is fitted to the inner crown by external force (occlusal force), the outer crown causes elastic deformation. The contractile force of the outer crown acts as pressure on the inner crown shaft wall and is maintained. Therefore, only metals with excellent elasticity and strength were used in conventional improved telescopes.
The reality is that acrylic resin, which is commonly used as a denture base material, cannot be used. For this reason, conventionally, in order to obtain a denture base with the improved telescope, an outer crown corresponding to the inner crown on the abutment tooth was manufactured in advance, and then the outer crown was attached to a separately manufactured metal base. It was necessary to prepare the denture base and then use acrylic resin to form the resin part of the denture base. As described above, it required a large amount of manufacturing cost because it required several steps and required the use of expensive materials. <Problems to be Solved by the Invention> An object of the present invention is to provide an improved telescope with an appropriate retaining force for the inner crown, and to provide a simple method for manufacturing the improved telescope without going through several steps. The purpose of the present invention is to provide a thermoplastic resin denture base that can be manufactured using. <Means for Solving the Present Invention> The present invention is characterized by having a recess into which the internal crown on the abutment tooth is inserted, and the shape of the inner wall of the recess is conus-shaped or oval. The key point is that thermoplastic resin is used as the material for the denture base, which is a mold or a mixture thereof. In the denture base of the present invention, the shape of the inner wall of the recess into which the internal crown on the abutment tooth is fitted is a conus shape, an oval shape, or a mixed shape partially including these shapes. A telescope as shown in FIG. 1 can be exemplified. In either case, the retention force with the inner crown is expressed by the static friction force generated by the contraction force after the denture base recess is elastically deformed when the inner crown is inserted into the denture base recess. Many factors are involved in this maintenance force, such as the functional force (force caused by occlusion) applied to the denture base recess, the elasticity of the denture base material, the surface roughness of the denture base recess, the shape and height of the inner crown, and so on. Therefore, in actual use, in order to obtain an appropriate retaining force, consider the condition of the tooth loss, the characteristics of the thermoplastic material used, the manufacturing method, etc., and select an appropriate telescope from the above-mentioned types. is selected. The conus type has a unique conical shape, so
It is preferable that there is little slippage during attachment/detachment or function, and even if a part of the denture is worn out, when functional force is applied again, a new inner crown is brought into contact with the denture base recess, and a decrease in retention force is less likely to occur. Although the conus angle is not particularly limited, it is generally preferred to be about 6 degrees as an angle that reliably holds the prosthesis and does not interfere with the retained teeth during attachment and detachment. There is no particular limitation on the wall thickness of the denture base recess, but the wall thickness that provides appropriate elasticity and rigidity is 0.3 mm to 8 mm.
Preferably it is 0.5 mm to 2 mm. The thermoplastic resin used in the present invention has good formability that enables the molding of the denture base having the recessed portions, has appropriate elasticity and rigidity, and can be colored to resemble the color of the gums. In addition, the resin is required to have toughness that does not cause stress cracks during use. Therefore, as the thermoplastic resin, polymethylpentene-1, transparent nylon, polycarbonate, aromatic polyester copolymer, polyester carbonate, polyethylene terephthalate, transparent ABS, polysulfone resin, etc. are used. Among these, polysulfone-based resins such as polysulfone and polyethersulfone, and polyester-based resins such as aromatic polyester copolymers and polyester carbonates are preferred because of their excellent elasticity, rigidity, and strength. The polysulfone resin used as a preferred embodiment in the present invention is defined as a polyarylene polyether polysulfone in which arylene units are located in a disordered or ordered manner with ether and sulfone bonds. for example UCC polysulfone Udel with the structure

One example is polyether sulfone Victrex manufactured by ICI, which has the structure of [Formula]. Similarly, the aromatic polyester copolymer used as a preferred embodiment is a mixture of terephthalic acid and isophthalic acid or their functional derivatives (however, the molar ratio of terephthalic acid groups to isophthalic acid groups is 9:1 to 1:9). ) and 2,2-bis(4'-
It is defined as a copolymer obtained from bisphenol (hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A). The aromatic polyester copolymer can be blended with an appropriate amount of polycarbonate, polyester carbonate, or polyethylene terephthalate depending on the purpose. These resins have good compatibility with the aromatic polyester copolymer, and have the properties required for aromatic polyester copolymers for use in denture bases, such as transparency, color tone, strength, rigidity, and
Processing temperature can be lowered without reducing adhesion to acrylic resin artificial teeth, resistance to acrylic monomers, etc. Furthermore, the aromatic polyester copolymer is preferable because it has the advantage of being less yellowish and being able to be colored in a variety of colors required for denture bases. In particular, when the mixture is composed of 30 to 95% by weight of the aromatic polyester copolymer and 70 to 5% by weight of polycarbonate, the transparency, color tone, strength, rigidity,
Adhesiveness to acrylic resin artificial teeth, resistance to acrylic monomers, moldability of denture bases by injection molding, compression molding, etc. are more well-balanced than that of the aromatic polyester copolymer alone, and the surface hardness is also good. It is preferable because it has excellent properties as a denture base, such as high abrasion resistance with a toothbrush, and good finishing workability by machining after molding the denture base. The polyester carbonate used in the present invention is obtained from (A) aromatic dicarboxylic acid and/or its functional derivative, (B) aromatic dihydroxy compound and/or its functional derivative, (C) diaryl carbonate or phosgene. be. Specific examples of component (A) include terephthalic acid, isophthalic acid, methyl terephthalic acid, methyl isophthalic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, naphthalene dicarboxylic acid, or ester-forming derivatives thereof, such as lower alkyl ester, phenyl ester,
Examples include acid halides. Specific examples of component (B) include hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 4,4'-dihydroxydiphenyl, 1,1-bis(4-hydroxyphenyl), phenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)ethane, bis(4-
(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3,5-dibromphenyl)propane, 4,4'-dihydroxydiphenylsulfone, 1,2-bis(4-hydroxyphenyl)ethane Alternatively, examples thereof include ester-forming derivatives thereof. One or more of these may be used. Among these, bisphenol A is particularly preferred. The diaryl carbonate of component (C) includes diphenyl carbonate, dicresyl carbonate,
Examples include di-β-naphthyl carbonate and bis(2-chlorophenyl) carbonate. Among these combinations, terephthalic acid (or terephthalic acid diphenyl ester), bisphenol A and diphenyl carbonate are particularly preferably used. The thermoplastic resin used in the present invention may be colored with antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, dyes, pigments, etc., to the extent that the purpose of the present invention is not impaired. One or more conventional additives can be added, such as additives. There are no particular limitations on the method for obtaining the thermoplastic resin denture base of the present invention. Known methods known as denture base manufacturing methods using thermoplastic resin, such as injection molding using a plaster mold, extrusion molding, compression molding, and transfer molding, are applicable. Among them, Japanese Unexamined Patent Application Publication No. 1439/1983 and Utility Model Application No. 1983-1439
Compression molding methods such as those exemplified in Japanese Patent No. 5415 are preferred. That is, in methods other than compression molding, such as injection molding, higher speed and higher pressure molding is required in order to completely fill the particularly thin recesses in the closed mold with thermoplastic resin. The molded product is more likely to crack because the residual strain in each part of the denture base becomes excessive. On the other hand, in compression molding, the thermoplastic resin is heated and softened on the divided lower flask, and then the upper flask is joined together and pressurized.
The softened resin is also sufficiently filled into the recessed portion without causing excessive residual strain. Hereinafter, the present invention will be specifically explained with reference to Examples, but these are merely exemplifications of preferred embodiments, and the present invention is not limited to the scope of the Examples. Example 1 For a case of 67 missing teeth in the upper jaw, we first followed the standard method and attached a metal conus-shaped internal crown with a conus angle of 5 to 8 degrees to the 45th tooth, took an impression, and made a plaster model. was produced. With wax for wax dentures on the plaster model | 4567
Gingiva was formed to cover the corresponding area, and an acrylic resin artificial tooth (trade name: GC Acrylic Resin Molar) | 4567 was planted in the alveolar ridge area to form a wax denture. After the denture base wax model was embedded in plaster in a flask by a conventional method, the flask was heated to soften and flow the wax. Next, polyether sulfone (ICI, Victrex) for molding the denture base was placed on the divided lower flask.
By positioning a plate-shaped molded product colored like gingiva (4100G) and blowing hot air at 380℃,
After softening the molded product, the upper flask in which the artificial tooth was embedded was bonded together, compressed using a compression molding machine, and then allowed to cool naturally. After cooling, the upper and lower flasks were separated and the denture base was taken out. The partial denture base shown in Fig. 2 (side view) and Fig. 3 (X-X' sectional view) is obtained, and is well maintained on the inner crown on the abutment tooth by the elastic force of the resin. It was also fitted extremely well into the patient's mouth. Both the ease of putting on and taking off and the feeling of wearing were good. Example 2 For a case of tooth loss in the upper jaw 65421｜12456 , a metal conus-shaped internal crown with a conus angle of 5 to 8 degrees was attached to the 73｜37 tooth according to the conventional method, an impression was taken, and plaster was applied. I made a model. Apply wax for dentures 7 to 1 on the plaster model.
｜Cover parts 1 to 7 to form an interdental space, and then plant acrylic artificial teeth (product name: GC Acrylic Resin Anterior Teeth, Molars) 6 to 1 | 1 to 6 in the alveolar ridge to form a wax denture. Ta. After the denture base wax model was embedded in a flask by a conventional method, the flask was heated to soften and flow the wax. Next, on the divided lower flask, a gingiva-colored aromatic polyester copolymer for denture base molding (methylene chloride solution of mixed acid chloride with a ratio of terephthalic acid dichloride/isophthalic acid dichloride of 1:1 and Obtained from an alkaline aqueous solution of phenol A by interfacial polymerization, the logarithmic viscosity in phenol/tetrachloroethane (6:4 weight ratio) is
0.62) and polycarbonate (Mitsubishi Gas Chemical S2000) in a ratio of 7:3. Position 4 pieces,
The molded article was softened by blowing hot air at 340°C. After softening, the upper flask in which the artificial tooth was embedded was bonded together, compressed using a compression molding machine, and then allowed to cool naturally. After cooling, the upper and lower flasks were separated and the denture base was taken out. The entire base shown in Fig. 4 (side view) and Fig. 5 (X-X' sectional view) is obtained, and is well maintained by the elastic force of the resin on the internal crown on the abutment tooth. It fits very well in the mouth. Both the ease of putting on and taking off and the feeling of wearing were good. Comparative Examples 1 and 2 In Examples 1 and 2, heat-polymerized acrylic resin (commercial product), which is commonly used as a material for denture bases, was used instead of the mixture of polyether sulfone, aromatic polyester copolymer, and polycarbonate, respectively. Name: Akron, manufactured by GC Dental Industry)
was polymerized in boiling water for 12 hours to obtain a denture base. When the resulting partial and full floors were fitted onto the internal crowns on the abutment teeth in the same manner as in Examples 1 and 2, the floors broke at the fitting portions in both cases. <Effects of the Invention> The denture base of the present invention is made of thermoplastic resin, and the shape of the inner wall is conus-shaped, oval-shaped, or a mixture partially containing these shapes, corresponding to the inner crown on the abutment tooth. Since it has a concave portion that is a mold, it has the following effects. Since it is made of a thermoplastic resin having appropriate elasticity and rigidity, it is easy to adjust the retaining force on the inner crown, and good attachment/detachability and wearing comfort are obtained. Since it is integrally molded including the recess that fits into the internal crown on the abutment tooth, the process is simple and productivity is high. It can be manufactured at low cost because it does not require the use of an expensive metal outer cap and a metal floor that is soldered to the outer cap, which are used in conventional telescopes. It has functionality, fit, and cleaning properties similar to those of the improved telescope, such as the Konus Krone, and eliminates the excessive burden on remaining teeth and gums seen with clasps. Since it is a one-piece molded product, the entire denture can be designed and manufactured with a strong structure.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of various telescopes. Second
FIG. 4 is a side view showing an embodiment of the present invention. Figures 3 and 5 are X-X in Figures 2 and 4, respectively.
X′ cross-sectional view. 1...Outer crown, 2...Inner crown, 3...Artificial tooth, 4...
... Gingival area, 5... Concavity in the denture base.

Claims (1)

[Scope of Claims] 1. A thermoplastic resin denture having a recess into which an internal crown on an abutment tooth is inserted, and the shape of the inner wall of the recess is a conus shape, an oval shape, or a mixture thereof. floor. 2. The thermoplastic resin denture base according to claim 1, wherein the thermoplastic resin is a polysulfone resin or a polyester resin. 3. The thermoplastic resin denture base according to claim 2, wherein the polyester resin is an aromatic polyester copolymer.