Partial dentures

Abstract

To provide partial dentures with a shortened clasp length, while securing gripping and maintenance functions.SOLUTION: Partial dentures 10 include an artificial tooth 11 to be installed in a missing part of a molar and a plurality of clasps 12 integrally formed with the artificial tooth 11 and to be hooked to an undercut part 5a in an abutment tooth 5. Each of the plurality of clasps 12 includes a front clasp 12a and a rear clasp 12b. An inner surface 16 in a root side of the front clasp 12a has such a shape that at least a dental root side in the height direction advances rearward along the front surface of the undercut part 5a as it approaches the dental root, and a tip of the front clasp 12a is located on the artificial tooth 11 side with respect to a center location X of the abutment tooth 5 in a tooth row direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a partial denture having a clasp. [Background technology]

[0002] Partial dentures are used as a dental prosthesis to replace partially lost teeth. hook Some partial dentures have clasps as a means of fixing them to the teeth (remaining natural teeth). Because clasps protrude from the artificial teeth, they must be stronger than other parts of the partial denture. hook Elasticity is also required to secure it to the teeth.

[0003] Patent Document 1 describes a clasp for a partial denture. In this clasp, a first clasp arm runs on one side of the abutment tooth, and a second clasp arm runs on the other side of the abutment tooth. When the partial denture is attached, the clasp cusps of the first clasp arm and the second clasp arm contact the abutment tooth so as not to bias the abutment tooth. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-61608 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional clasps are designed so that the tip side of the front clasp and the tip side of the rear clasp come into contact with the undercut part of the clasp and hold the clasp from the front and rear, thereby exerting a gripping function and a retaining function. Here, when the denture is put on and taken off, the front clasp and the rear clasp need to be opened back and forth, but the displacement amount of the base side of the clasp when opened back and forth is smaller than that of the tip side. Therefore, if the base side of the front clasp and the base side of the rear clasp come into contact with the undercut part of the clasp on the tooth root side in the height direction, the front clasp and the rear clasp need to be opened back and forth widely, and there is a risk that the clasp will break on the root side. In conventional clasps, the base side of the clasp is separated from the undercut part of the clasp on the tooth root side in the height direction so that the clasp will not break on the root side when the denture is put on and taken off.

[0006] However, in conventional clasps, in order to achieve the gripping and retaining functions, it is necessary to ensure the length of the tip of the clasp, which results in the clasp itself becoming longer, resulting in a decrease in aesthetics.

[0007] The present invention has been made in consideration of the above circumstances, and aims to realize a partial denture in which the length of clasps is shortened while ensuring the grasping function and the retention function. [Means for solving the problem]

[0008] The inventors of the present application took notice of the emergence of denture materials that are easy to bend, and thought that even if a clasp was designed so that the base side of the clasp came into contact with the undercut portion of the abutment tooth on the tooth root side in the height direction to exert its gripping and retention functions, it would be possible to realize a partial denture in which the clasp would not break at the base side when the partial denture was put on and taken off.

[0009] Based on this idea, the first invention is provided with an artificial tooth to be placed at a missing part of a molar, and a plurality of clasps that are integrally formed with the artificial tooth and hooked onto undercut parts of the clasps, hook An anterior clasp that passes through the front of the teeth; hookThis partial denture has a posterior clasp that passes behind the teeth, and the inner surface at the base of the anterior clasp in a cross-sectional view has a shape that advances rearward as it approaches the root, at least on the root side in the height direction, so as to follow the front surface of the undercut portion, and the tip of the anterior clasp is located on the artificial tooth side rather than the center position of the abutment teeth in the dentition direction.

[0010] The second invention is based on the first invention, and further includes a protruding rest on the base side of the front clasp, the rest being placed on an upper portion above the most prominent portion of the clasp.

[0011] In a third aspect of the present invention, in the second aspect of the present invention, the protruding length of the rest is set so that the tip of the rest does not reach the top surface of the abutment tooth.

[0012] The fourth invention is provided with an artificial tooth to be placed at a missing part of an anterior tooth, and a plurality of clasps integrally formed with the artificial tooth and hooked on undercut parts of the clasps, hook An anterior clasp that passes through the front of the teeth; hook and a posterior clasp that passes behind the teeth, and the inner surface at the base of the anterior clasp in a cross-sectional view has a shape that advances rearward as it approaches the root, at least on the root side in the height direction, so as to follow the front face of the undercut portion, and the tip of the anterior clasp is located on the artificial tooth side further than a position two-thirds of the way from the artificial tooth side of the abutment tooth in the dentition direction. Effect of the Invention

[0013] In the present invention, the inner surface of the base side of the front clasp is, at least on the tooth root side in the height direction, gradually becomes thinner along the surface of the undercut portion of the clasp as it approaches the tooth root. hookThe front clasp has a shape that advances toward the teeth. Therefore, the partial denture can be designed so that the front clasp exerts a gripping function and a retention function at the base side. This allows the length of the clasp to be shortened, so in the present invention, the tip of the front clasp is positioned closer to the artificial tooth than the center position of the abutment teeth in the dentition direction. According to the present invention, a partial denture with a shortened clasp length can be realized while ensuring the gripping function and the retention function. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1(a) is a perspective view of a partial denture according to an embodiment, and FIG. 1(b) is a perspective view of the partial denture attached to a dentition model. [Diagram 2] Figure 2(a) is a front view of a dental model according to an embodiment with a partial denture attached, Figure 2(b) is a front view of the dental model with the partial denture removed, and Figure 2(c) is a top view of the dental model with the partial denture attached. [Diagram 3] 3(a) is a cross-sectional view taken along line AA in FIG. 2(c), and FIG. 3(b) is a cross-sectional view taken along line BB in FIG. 2(c). [Figure 4] FIG. 4 is a top view of the partial denture described in the "Effects of this embodiment" section when it is attached to a dental model. [Diagram 5] Figure 5(a) is a front view of a partial denture according to a first modified embodiment, Figure 5(b) is a view of the partial denture from slightly forward on the upper side, and Figure 5(c) is a view of the partial denture from slightly backward on the upper side. [Figure 6] FIG. 6 is a view of a partial denture according to a first modified embodiment, seen from a side slightly behind. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments and modifications are merely examples of the present invention and are not intended to limit the scope of the present invention, its applications, or its uses.

[0016] In this embodiment, the partial denture 10 is made of a single material such as a resin material. In the following, a partial denture 10 for back teeth will be described as an example.

[0017] [Partial denture configuration] As shown in Fig. 1(a), the partial denture 10 is a type of partial denture without a base (denture base). As shown in Fig. 1(b), the partial denture 10 is a partial denture for back teeth, and has two teeth at a restoration site R where a back tooth is missing. hook It is fitted between teeth (natural teeth) 5. The partial denture 10 comprises an artificial tooth 11 to be placed in the missing portion of a molar, and a plurality of clasps 12a, 12b integrally formed with the artificial tooth 11, which are integrally formed. At least the tip side of an upper outline 31 (described later) of each clasp 12a, 12b is on the surface of the undercut portion 5a, and is hooked onto the undercut portion 5a of the clasp 5. In the partial denture 10 of this embodiment, the artificial tooth portion is made up of one artificial tooth 11, but it may be made up of a plurality of artificial teeth 11 arranged horizontally.

[0018] Here, the "undercut portion 5a" is hook The portion of the tooth 5 below the maximum protuberance 5b and cannot be seen from directly above. hook It is the part of the tooth 5 that bulges outward the most. In Fig. 1(b) and Fig. 2(a)-(b), the maximum protuberance 5b is indicated by a dashed line. The part of the abutment tooth 5 above the maximum protuberance 5b is referred to as the "upper part 5c."

[0019] The clasps 12a and 12b are two hook For each of the teeth 5, hook Two teeth are provided on each side of the tooth 5. hook For tooth 5, hook A front clasp (outer clasp) 12a passing in front of the tooth 5; hook A rear clasp (inner clasp) 12b that passes behind the tooth 5 is provided.

[0020] In this specification, the "front side" refers to the lip side when the partial denture 10 is worn, and the "rear side" refers to the throat side. Furthermore, regardless of whether it is an upper or lower tooth, the top surface 5e side of the abutment 5 and the partial denture 10 may be referred to as the "upper side" and the root side as the "lower side."

[0021] The front clasp 12a protrudes laterally from the front of the artificial tooth 11 when the partial denture 10 is attached to the restoration area R, hook The rear clasp 12b is curved along the front surface of the tooth 5. When the partial denture 10 is attached to the restoration site R, the rear clasp 12b protrudes laterally from the rear of the artificial tooth 11. hook It is curved along the rear surface of tooth 5.

[0022] [Clasp configuration] As shown in Fig. 2(a), the clasps 12a and 12b are provided with a clasp body 21 that exerts a gripping function and a retaining function, and a rest 22 that exerts a supporting function, which are integrally formed. The clasp body 21 is gradually reduced in height from the base to the tip. The gripping function is a function that resists forces acting horizontally on the artificial tooth 11. The retaining function is a function that resists a separation force that tends to lift the partial denture 10. The supporting function is a function that resists an occlusal force that tends to sink the partial denture 10.

[0023] As shown in Fig. 2(a), at the base side of the front clasp 12a, the rest 22 placed on the upper part 5c of the clasp 5 protrudes obliquely toward the top surface 5e of the clasp 5. At the base side of the rear clasp 12b, the rest 22 placed on the upper part 5c of the clasp 5 protrudes obliquely toward the top surface 5e of the clasp 5. The inner surface of each rest 22 in a cross-sectional view gradually becomes narrower as it approaches the top surface 5e, so as to follow the surface of the upper part 5c. hook It has a shape that advances toward the tooth 5 (see FIG. 3(a)). Note that "the base side of the clasps 12a, 12b" refers to the base side of the clasps 12a, 12b from the center in the length direction.

[0024] Specifically, the upper outline 31 constituting the outer periphery of the clasps 12a and 12b has a mountain-shaped portion 31a formed at the base, and the mountain-shaped portion 31a constitutes the outer periphery 22a of the rest 22. The area surrounded by the line b (dotted line in FIG. 2(a)) connecting the two bottoms of the mountain-shaped portion 31a and the outer periphery 22a corresponds to the rest 22. Here, the ratio (h / w) of the height h of the rest 22 (the distance from the line b to the top of the mountain-shaped portion 31a) to the width w of the rest 22 (the length of the line b) can be, for example, 0.15 or more (preferably 0.25 or more). The "upper outline" is a line constituting the outer periphery of the upper side of an object in a front view. The "lower outline" is a line constituting the outer periphery of the lower side of an object in a front view.

[0025] The outer circumference 22a of the rest 22 crosses the maximum protuberance 5b in the section from the bottom of the mountain-shaped portion 31a (bottom of the tip side of the clasps 12a, 12b) to the top. The top of the mountain-shaped portion 31a is in the range of the root side of the clasps 12a, 12b, and is located in the upper part 5c on the clasp 5. The outer circumference 22a passes through the upper part 5c of the clasp 5 in the section from the top of the mountain-shaped portion 31a to the bottom (bottom of the root side of the clasps 12a, 12b). This section passes near the upper outline 6 of the clasp 5. Most of the outer circumference 22a of the rest 22 passes through the upper part 5c of the clasp 5. This allows the rest 22 to perform a support function. The protruding length (height) of the rest 22 is set so that the tip of the rest 22 does not reach the top surface 5e of the clasp 5. 2(c), the tip of the rest 22 does not cover the top surface 5e of the clasp 5. The lower outline 32 of the clasps 12a and 12b passes near the upper end of the gums.

[0026] The cross-sectional shape of the curved inner surfaces 15-17 connecting the inner surface 16 of the front clasp 12a, the side surface 15 of the artificial tooth 11, and the inner surface 17 of the rear clasp 12b is such that the tooth root side in the height direction is aligned along the surface of the undercut portion 5a of the clasp 5 over the entire length, and the closer to the tooth root, the hook The shape gradually advances toward the tooth 5 side (hereinafter, may be referred to as a "lower advance shape"). hookThe surface of the undercut portion 5a of the tooth 5 has a shape that gradually recedes around the entire circumference as it approaches the tooth root (see Fig. 3(a) and Fig. 3(b)). Note that the "tooth root side in the height direction" refers to the side closer to the tooth root than the center of the target surface.

[0027] 3(a), the inner surface 16 of the base side of the anterior clasp 12a in cross section has a shape that gradually advances rearward as it approaches the tooth root, at least on the tooth root side in the height direction, so as to follow the front surface of the undercut portion 5a. The inner surface 16 of the tip side of the anterior clasp 12a in cross section has a shape that gradually advances rearward as it approaches the tooth root, so as to follow the front surface of the undercut portion 5a over the entire height direction.

[0028] In addition, the inner surface 17 of the base side of the posterior clasp 12b in cross section has a shape that gradually advances forward as it approaches the tooth root, at least on the tooth root side in the height direction, so as to follow the rear surface of the undercut portion 5a. The inner surface 17 of the tip side of the posterior clasp 12b in cross section has a shape that gradually advances forward as it approaches the tooth root, so as to follow the rear surface of the undercut portion 5a over the entire height direction.

[0029] As shown in FIG. 3(b), the side surface 15 of the artificial tooth 11 in cross section is gradually narrowed toward the tooth root so that at least the tooth root side in the height direction is aligned with the side surface of the undercut portion 5a. hook It has a shape that advances toward the tooth 5. The tooth root side of the curved inner surfaces 15 to 17 described above is formed in a steep slide shape.

[0030] In this embodiment, the inner surfaces 16, 17 on the tip side of each of the front clasp 12a and the rear clasp 12b contact the undercut portion 5a of the clasp 5 over the height direction to embrace the undercut portion 5a. Also, the inner surfaces 16, 17 on the base side of each of the front clasp 12a and the rear clasp 12b contact the undercut portion 5a of the clasp 5 at least on the root side in the height direction to embrace the undercut portion 5a. Therefore, the front clasp 12a and the rear clasp 12b exert a gripping function and a retaining function both on the tip side and the base side.

[0031] On the other hand, in the partial denture 10, the gaps at the lower ends of the curved inner surfaces 15-17 described above become narrow. Therefore, when attaching and detaching the partial denture 10 in the vertical direction, it is necessary to open the front clasps 12a and the rear clasps 12b widely in the front-rear direction. In this embodiment, the partial denture 10 is made of a resin material (e.g., polyamide resin) that can withstand a large amount of deflection so that the clasps 12a, 12b will not break at their bases even if the front clasps 12a and the rear clasps 12b are opened widely in the front-rear direction.

[0032] In this embodiment, the front clasp 12a and the rear clasp 12b exert a gripping function and a retaining function even at the base side, so that the length of the clasps 12a and 12b can be shortened. The tip of the front clasp 12a is located on the artificial tooth 11 side of the center position X of the clasp 5 in the dentition direction (the direction in which the teeth are arranged). The tip of the rear clasp 12b is also located on the artificial tooth 11 side of the center position X of the clasp 5 in the dentition direction.

[0033] Here, the dentition direction is the direction along an imaginary line D drawn so as to pass through roughly the center in the front-to-back direction at the crests of the teeth 5 and 11 when viewed from above (see FIG. 2(c)). Specifically, the center position X is the center position of the length of the range R of the imaginary line D that passes through the exposed part of the abutment tooth 5 on the gum, and is the position of a line X perpendicular to the imaginary line D.

[0034] In addition, the tips of the clasps 12a and 12b are, in plan view, hook The clasps 12a and 12b are located closer to the artificial tooth 11 than the outwardly bulging portion of the undercut portion 5a of the tooth 5. In a plan view, the clasps 12a and 12b do not have a bending portion where the inner surface starts to bend inward. Note that while conventional clasps extend beyond the center position X and have tips that point obliquely upward along the upper end of the gums, the clasps 12a and 12b of this embodiment have tips that point obliquely downward.

[0035] [Manufacturing method for partial dentures] The manufacturing method of the partial denture 10 includes a step of cutting out the partial denture 10 having a three-dimensional shape corresponding to the processing data from a resin material by cutting with a cutting machine based on processing data that represents the three-dimensional shape of the partial denture 10. The partial denture 10 is manufactured by cutting out the resin material.

[0036] In this manufacturing method, first, a preparation step is performed to prepare processing data representing the three-dimensional shape of the partial denture 10. Specifically, in the preparation step, an intraoral scanner is used to scan (optically photograph) the inside of the patient's mouth, and scan data representing the three-dimensional shape of the restoration area R and its surroundings is obtained. The scan data also includes the three-dimensional shapes of the teeth that will mesh with the partial denture 10. The scan data is input into a CAD / CAM system.

[0037] Next, in the CAD / CAM system, a model of the partial denture 10 is performed based on the scan data, and the above-mentioned processing data is created. In this modeling, the shape of the partial denture 10 is designed so that the tooth root side in the height direction of the curved inner surfaces 15-17 has a downwardly protruding shape over the entire length, and rests 22 are formed on each of the clasps 12a, 12b.

[0038] Next, a cutting step is performed in which a three-dimensional partial denture 10 corresponding to the processing data is cut out of the circular resin disk by cutting using a cutting machine based on the processing data. Then, a polishing step is performed to polish the partial denture 10, and a step is performed to apply a coating to the partial denture 10, after which the partial denture 10 is completed and provided to the dentist.

[0039] [Effects of this embodiment] According to this embodiment, it is possible to realize a partial denture 10 in which the length of the clasps 12a, 12b is shortened while ensuring the grasping function and the retention function.

[0040] Here, the inventor of the present application came up with the idea that by shortening the clasps 12a, 12b, it is possible to reduce the height of the base side of the clasps 12a, 12b, and accordingly, a space is created between the upper outline 31 and the top surface 5e of the clasp 5 at the base side of the clasps 12a, 12b, and this space can be used for the rest 22. In this embodiment, the rest 22 is provided on the clasps 12a, 12b so as not to reach the top surface 5e of the clasp 5. Here, the rest of a conventional partial denture is arranged from the upper end of the side of the artificial tooth to the hook It protrudes towards the tooth. hook In the case of teeth, a recess into which the rest fits is formed by cutting the upper surface. hook The rest protruding toward the tooth 5 side can be omitted. hook It is not necessary to grind the teeth 5, and a partial denture 10 that places a small burden on the patient can be realized.

[0041] In this embodiment, the upper end of the side of the artificial tooth 11 is hook A rest 23 protruding toward the teeth 5 may be provided. In the case of the partial denture 10 for the molars, hook The area of ​​the rest 22 is easily secured for the tooth 5, and the support function is easily obtained. Therefore, as shown in FIG. hook The rest 23 may be provided only on the tooth 5 side.

[0042] [First Modification of the Present Embodiment] This modification is a partial denture (partial denture for front teeth) 10 in which artificial teeth 11 are placed in the areas where front teeth are missing. In the partial denture 10 of this modification, the artificial teeth portion is made up of two artificial teeth 11 as shown in Fig. 5, but it may be made up of one artificial tooth 11 or three or more artificial teeth 11.

[0043] As shown in Fig. 5(a), each clasp 12a, 12b has a clasp body 21 that exerts a gripping function and a retaining function, and a rest 22 that exerts a supporting function, as in the above-mentioned embodiment. At the base side of each clasp 12a, 12b, the rest 22 that is placed on the upper part 5c above the most prominent part of the clasp 5 protrudes obliquely toward the crest 5e of the clasp 5. In the partial denture 10, the upper end 11a of the side of the artificial tooth 11 covers the crest 5e of the clasp 5 from above, as shown in Fig. 5(b).

[0044] In addition, the inner surfaces 16 and 17 of the base sides of the front clasp 12a and the rear clasp 12b in a cross-sectional view are gradually inclined toward the tooth root so as to follow the surface of the undercut portion 5a of the clasp 5 at least on the tooth root side in the height direction, as in the above embodiment. hook It has a shape that advances toward the tooth 5 (see FIG. 6). In this modification, the front clasp 12a and the rear clasp 12b exert a gripping function and a retaining function at both the tip side and the base side, so that the length of the clasps 12a and 12b can be shortened.

[0045] The tip of the front clasp 12a is located closer to the artificial tooth 11 than a position Y that is two-thirds of the way from the artificial tooth 11 side of the abutment 5 in the dentition direction. The dentition direction is a direction along an imaginary line E that is drawn to pass through the tops of the teeth 5, 11 in a top view (see FIG. 5(b)). Specifically, position Y is the position of a line Y that is perpendicular to the imaginary line E at a position two-thirds of the way from the artificial tooth 11 side, in a range R that passes through the exposed part of the gum of the abutment 5. The tip of the front clasp 12a may be located closer to the artificial tooth 11 than the center position of the abutment 5 in the dentition direction.

[0046] [Other embodiments] In the above-described embodiment, the partial denture 10 may be of the type having a base (denture base).

[0047] In the above-described embodiment, the rest 22 may be omitted from one or both of the front clasp 12a and the rear clasp 12b. [Industrial Applicability]

[0048] The present invention is applicable to partial dentures having clasps, etc. [Explanation of symbols]

[0049] 5 hook teeth 5a Undercut section 5b Maximum Toyotaka section 5c Upper 10 Partial dentures 11 Artificial teeth 12a clasp, front clasp 12b clasp, rear clasp 16 Inner surface of front clasp 17 Inner surface of rear clasp 21 Clasp body 22 Rest

Claims

1. An artificial tooth to be placed in the missing molar area; a plurality of clasps integrally formed with the artificial tooth and hooked onto undercut portions of the clasps; The plurality of clasps include an anterior clasp passing through a front side of the hook and a posterior clasp passing through a rear side of the hook, The inner surface of the base side of the front clasp in a cross-sectional view has a shape that at least on the tooth root side in the height direction advances rearward as it approaches the tooth root so as to follow the front surface of the undercut portion, A partial denture, wherein the tip of the front clasp is located closer to the artificial tooth than the center position of the clasp in the dentition direction.

2. 2. The partial denture according to claim 1, wherein a rest is protruding from the base side of the front clasp to be placed on an upper portion of the clasp that is above the maximum protuberance portion of the clasp.

3. 3. The partial denture according to claim 2, wherein the protruding length of said rest is set so that the tip of said rest does not reach the top surface of said abutment teeth.

4. An artificial tooth to be placed in the area of ​​a missing front tooth; a plurality of clasps integrally formed with the artificial tooth and hooked onto undercut portions of the clasps; The plurality of clasps include an anterior clasp passing through a front side of the hook and a posterior clasp passing through a rear side of the hook, The inner surface of the base side of the front clasp in a cross-sectional view has a shape that at least on the tooth root side in the height direction advances rearward as it approaches the tooth root so as to follow the front surface of the undercut portion, A partial denture, wherein the tip of the front clasp is located closer to the artificial tooth than a two-thirds position from the artificial tooth side of the clasp in the dentition direction.

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