Artificial dental root

Abstract

To provide an artificial dental root that is optimal to accelerate the reproduction of paradentium in consideration of the flow of liquid.SOLUTION: An artificial dental root (10) is in the form a circular cylinder with a crown (20) on one end and a root apex (39) on the opposite end. Provided between the crown and the root apex are two or more vertically arranged spheres (31, 32), and a boundary (38) between the spheres is formed of a smooth curved surface concave toward an axis (P) side. As a result of this, repetitive flow of blood in a bone marrow occurs easily, which accelerates formation of a periodontal membrane and reproduces and restores paradentium.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an artificial tooth root that promotes the regeneration of periodontal tissues.

Background Art

[0002] As a technique for restoring missing teeth, dental implants are known. In an implant, a titanium artificial tooth root having a thread groove at the lower part is implanted into the jawbone, and a rigid fixation between the bone and the artificial tooth root is formed as known as osseointegration. However, the implant technique has the following problems.

[0003] First, due to the occlusal movement of the teeth, there is a risk that the bone at the joint with the implant will collapse over time. The reason is that since the implant is directly screwed (fixed) to the bone, the phenomenon of the screw loosening occurs due to the occlusal movement. That is, there is no screw that does not loosen under the action of mechanical energy.

[0004] Also, there is a problem that a periodontal ligament is not formed between the bone and the implant.

[0005] In the case of natural teeth, a periodontal ligament is provided between the bone and the tooth. The periodontal ligament is a fenestrated blood vessel, and due to the presence of the fenestrations, a self-cleaning action that flushes away invaders such as caries bacteria and periodontal bacteria and a phagocytic action of leukocytes are exerted. On the other hand, in the case of an implant, since a periodontal ligament is not formed, the above-described action of the immune system cannot be expected. For this reason, inflammation around the implant has become a problem in recent years. In addition, since the periodontal ligament has arteriovenous vessels, it has a function as a nervous system that senses tooth sensation. In the case of an implant, since a periodontal ligament is not formed, it is also a problem that it is difficult to feel tooth sensation.

[0006] On the other hand, an artificial tooth root disclosed in Patent Document 1 has been proposed. The artificial tooth root of Patent Document 1 is shown in FIG. 12. (A) in FIG. 12 is the artificial tooth root 1A for maxillary anterior teeth, (B) is the artificial tooth root 1B for mandibular anterior teeth or canines, (C) is the artificial tooth root 1C for maxillary and mandibular premolars, (D) is the artificial tooth root 1D for maxillary molars, and (E) is the artificial tooth root 1E for mandibular molars. The artificial tooth roots 1A to 1E are columnar, having a crown portion 2 at one end and a root tip 5 at the opposite end, and the bulging portion 4 and the recessed portion 3 are alternately formed on the side surface along the axial direction so as not to form a helix. The artificial tooth roots 1A to 1E are implanted in a non-fixed manner by being inserted into holes drilled in the jawbone. Since they are non-fixed, blood flows between the bone and the artificial tooth roots during chewing around the artificial tooth roots 1A to 1E, thus inducing leukocyte hematopoiesis. For this reason, the artificial tooth roots 1A to 1E have been proposed as tooth root membrane-inducing artificial tooth roots. When the tooth root membrane is induced, the above immune system is realized, so it can be said that the tooth root membrane-inducing artificial tooth root of Patent Document 1 is an epoch-making treatment method that overcomes the problems of implant technology.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, the shape of Patent Document 1 is designed such that the formation range of the recessed portion 3 with respect to the bulging portion 4 is small, and a groove formed by the recessed portion 3 is formed between the bulging portions 4. This is because it is expected that the recessed portion 3 functions like a thread groove, and the inserted artificial tooth roots 1A to 1E are designed to be difficult to come out of the bone. Also, the artificial tooth root 1D for maxillary molars and the artificial tooth root 1E for mandibular molars in Patent Document 1 are formed in a shape where the root tip 5 is bifurcated or trifurcated. This is because it is in accordance with the shape of natural teeth and is also designed in expectation of the effect of preventing the tooth from coming out of the bone.

[0009] The leukopoietic action related to the formation of the periodontal ligament is induced by the flow of blood between the bone and the artificial tooth root. The grooves formed by the concave portions 3 and the branches of the root apex 5 are shaped to retain the blood flow around the artificial tooth root, and it can be understood that a more optimal shape is required when emphasizing the formation of the periodontal ligament.

[0010] The present invention has been made in view of such circumstances, and aims to provide an artificial tooth root that is optimal for promoting the regeneration of periodontal tissues, including the formation of the periodontal ligament, by focusing on the flow of the liquid (bone marrow blood).

Means for Solving the Problems

[0011] In order to solve the above problems, the artificial tooth root according to the first aspect of the present invention is cylindrical, having a crown portion at one end and a root apex at the opposite end, and between the crown portion and the root apex, it is provided with two or more longitudinally arranged spheres, and the boundary portion of the spheres is formed in a smooth curved surface shape that is concave toward the axial center side.

[0012] In the artificial tooth root according to the second aspect, in the first aspect, it is also preferable that the base portion of the crown portion has a hemispherical shape, and the boundary portion between the base portion and the spheres is also formed in a smooth curved surface shape that is concave toward the axial center side.

[0013] In the artificial tooth root according to the third aspect, in the first or second aspect, it is also preferable that the root apex is formed by the spheres regardless of the tooth row.

[0014] In the artificial tooth root according to the fourth aspect, in any of the first to third aspects, it is also preferable that the boundary portion has a curved surface shape of the spherical surface of a virtual sphere that contacts the adjacent spheres and has substantially the same diameter as any of the spheres.

[0015] In the artificial tooth root according to the fifth aspect, in any of the first to fourth aspects, it is also preferable that the maximum outer diameter of the crown portion is made the same as the diameter of the sphere adjacent to the crown portion, and the diameter of the sphere is formed to be slightly smaller as it moves away from the crown portion.

[0016] In the dental implant according to the sixth aspect, in any one of the first to fourth aspects, it is also preferable that the maximum outer diameter of the tooth crown portion and the diameter of the sphere are all formed to be the same.

[0017] In the dental implant according to the seventh aspect, in any one of the second to sixth aspects, it is also preferable that the sphere and the hemisphere are arranged such that the vertices in the arrangement direction are in contact.

[0018] In the dental implant according to the eighth aspect, in any one of the second to sixth aspects, it is also preferable that the sphere and the hemisphere are arranged such that the vertices in the arrangement direction are separated by a distance equal to or less than the radius of any one of the spheres.

[0019] In the dental implant according to the ninth aspect, in any one of the first to eighth aspects, it is also preferable that the dental implant is made of zirconia.

Advantages of the Invention

[0020] According to the dental implant of the present invention, it has an optimal shape for promoting the regeneration of periodontal tissue, is effective in preventing infectious diseases, and can provide a tooth sensation. Consequently, it is possible to provide a new treatment that is also beneficial for extending human healthy life expectancy and preventing dementia.

Brief Description of the Drawings

[0021]

Figure 1

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MODE FOR CARRYING OUT THE INVENTION

[0022] Next, preferred embodiments of the present invention will be described with reference to the drawings.

[0023] FIG. 1 is a schematic view of the lower jaw showing the state where the dental implant 10 according to the first embodiment of the present invention is implanted, and is a view showing the state immediately after the surgery. Reference numeral 6 is the cortical bone of the jawbone, reference numeral 7 is the alveolar bone proper, and the vicinity of reference numeral 8 is the bone marrow. As shown in FIG. 1, the dental implant 10 according to this embodiment forms a cylindrical implantation socket 9 in the jawbone with a drill or the like, and is implanted in the implantation socket 9 in a non-fixed manner. Specifically, the diameter D10 of the dental implant 10 (see FIG. 2 described later) is designed to be slightly larger than the diameter D9 of the implantation socket 9, and the dental implant 10 is inserted by pushing it into the implantation socket 9 by utilizing the elastic deformation of the bone. Several months after this surgery, a provisional crown is attached to the crown portion 20 of the dental implant 10.

[0024] After the operation, a dental ligament begins to form around the artificial tooth root 10. As shown in FIG. 10 described later, the state of periodontal tissue regeneration can be clearly confirmed about five months after the operation. The mechanism by which the periodontal tissue is regenerated by the artificial tooth root 10 of this embodiment is as follows.

[0025] When the skeletal organs of mammals receive various external forces, when the directions of the external forces are different, or when the types of the external forces are significantly different, the joints of mammals serve as cushions, that is, bearing parts formed between the skeletons. Regardless of whether they are fibrous joints, cartilaginous joints, synovial joints, etc., the bones at the joint parts in mammals perform leukocyte hematopoiesis. Here, the part between the bone and the tooth corresponds to the joint of mammals. That is, an amplitude motion stimulus due to chewing is applied between the bone and the tooth, and by receiving an appropriate mechanical stimulus with repetition, leukocyte hematopoiesis is performed from stem cells in the bone marrow cavity.

[0026] As a basic principle, life phenomena are electrical phenomena in water-soluble colloidal organisms. When physiological saline is passed through apatite, a flow potential of 10 to 15 microamperes flows. The mechanical stimulus is converted into the hydrodynamics of the body fluid in the living body and then into a flow current, which triggers the genes of mesenchymal cells and forms BMP (Bone Morphogenic Protein). The induced BMP further triggers the genes of the cells, thereby causing hematopoiesis and osteogenesis to occur conjugately.

[0027] In the artificial tooth root 10, a flow current is generated in the blood in contact with the artificial tooth root 10 by the energy of the repetitive and flowing motion of about 0.2 millimeters due to chewing. When there is an increase in the flow current (from 1.5 microamperes to 10 microamperes) accompanying the increase in blood pressure by chewing, the genes of undifferentiated mesenchymal cells in the bone marrow are triggered, and bone marrow hematopoietic cells, osteoblasts, cementoblasts, and fibroblasts are formed, and leukocyte hematopoiesis is induced in the bone marrow cavity.

[0028] That is, focusing on the mechanism of leukopoietic action, it can be understood that the more blood repeatedly and fluidly flows around the artificial tooth root 10 due to occlusion, the more electrical stimulation is generated in the bone marrow, promoting cell changes in undifferentiated mesenchymal cells in the jawbone, accelerating the formation of the periodontal ligament, and regenerating and recovering the periodontal tissue.

[0029] Then, the conditions for the shape of the artificial tooth root suitable for the regeneration of the periodontal tissue can be seen. A structure with flexibility suitable for repetitive vibratory motion by chewing (occlusion) is required, and a shape that can effectively convert the principal stress of the mechanical energy applied from the crown part is needed. That is, the force applied by chewing (occlusion) is translated into hydrodynamics, and repetitive and fluid stress is applied to the entire tooth root part of the artificial tooth root, and a three-dimensional fluid potential orthogonal to the outside of the tooth root part is generated. Thus, it is considered that the artificial tooth root receives mechanical stimulation by the occlusal movement and promotes the regeneration of the periodontal tissue including the periodontal ligament through the fluid potential and gene induction.

[0030] Based on the above considerations, the artificial tooth root 10 was created.

[0031] (First Embodiment) FIG. 2 is a diagram for explaining the shape of the artificial tooth root 10 according to the first embodiment, and is (a) a front view, (b) a left side view, (c) a right side view, (d) a rear view, (e) a plan view, and (f) a bottom view. As shown in (a), the artificial tooth root 10 is composed of a tooth root part 30 inserted into the implantation socket 9 of the jawbone and a crown part 20 covering the provisional crown, and is formed in a columnar shape with an axis P as a whole. The upper part 22 of the crown part 20 is columnar or a conical shape with a narrowing upward, and the top surface 21 of the crown part 20 is formed as a horizontal plane. The shape of the cross section of the upper part 22 including the top surface 21 is a perfect circle (see (e-1)). The cross section of the upper part 22 may be elliptical (see (e-2)), but the base part 23 of the crown part 20 connected to the tooth root part 30 is substantially hemispherical.

[0032] The tooth root part 30 has spheres 31 and 32 arranged vertically on the axis P. The number of spheres is two or more, and the number of spheres may be increased according to the state of the patient's bone. The sphere 31 is adjacent to the root part 23 of the crown part 20 above and adjacent to the sphere 32 below. Hereinafter, for convenience of explanation, the sphere 31 is referred to as the first sphere 31 and the sphere 32 is referred to as the second sphere 32.

[0033] (b) As shown by the dashed line, the first sphere 31 and the second sphere 32 are adjacent to each other on the axis P such that the vertices (the lower vertex V35 of the first sphere 31 and the upper vertex V36 of the second sphere 32) are in contact, and the boundary part 38 between the first sphere 31 and the second sphere 32 is formed as a smooth curved surface that is recessed toward the axis P side. More specifically, the boundary part 38 between the first sphere 31 and the second sphere 32 is formed to have the curved surface shape of the spherical surface of a virtual sphere S1 that contacts the adjacent first sphere 31 and second sphere 32 and has a diameter approximately the same as the diameter D32 of the second sphere 32 (see (c)).

[0034] Similarly, the hemisphere of the root part 23 of the crown part 20 and the first sphere 31 are adjacent to each other on the axis P such that the vertices (the vertex V24 of the root part 23 and the upper vertex V34 of the first sphere 31) are in contact, and the boundary part 38' between the hemisphere of the root part 23 and the first sphere 31 is formed to have the curved surface shape of the spherical surface of a virtual sphere S2 that contacts the adjacent hemisphere of the root part 23 and the first sphere 31 and has a diameter approximately the same as the diameter D32 of the second sphere 32.

[0035] Note that the sizes of the virtual spheres S1 and S2 that form the shapes of the boundary parts 38 and 38' are not limited to the diameter D32 of the second sphere 32, and may be the spherical surface shape of a virtual sphere having a size approximately the same as any one of the spheres (the first sphere 31 or the second sphere 32 in this embodiment). The same shall apply in the description of other embodiments hereinafter.

[0036] The root tip 39 of the artificial tooth root 10 is formed by the second sphere 32. That is, the root tip 39 of the artificial tooth root 10 has the spherical surface shape of the second sphere 32, and the root tip 39 does not have a branched shape.

[0037] As shown in (c), the maximum outer diameter D20 of the crown portion 20 is made substantially the same as the diameter D31 of the first sphere 31 adjacent to the crown portion 20. The diameter D32 of the second sphere 32 is formed to be slightly smaller than the diameter D31 of the first sphere 31, preferably formed to be 80% - 95%, more preferably 85% - 93%.

[0038] As shown in (d), the major axis L10 is defined as the distance from the top surface 21 of the crown portion 20 to the root apex 39 of the root portion 30. The diameter D10 of the artificial tooth root 10 is the diameter D31 of the first sphere 31. The determination diagnosis of the size of the artificial tooth root 10, that is, the major axis L10 and the diameter D10, is performed by measurement using a CT image and is designed to be made to order according to the state of the patient's bone.

[0039] The artificial tooth root 10 having the above shape is formed as a molded product of zirconia using a 3D printer or the like. As a comparative example, although apatite has good biocompatibility, since it is a main component constituting teeth and bones, there is a risk of dental caries. Titanium also has good biocompatibility, but there is a problem of metal allergy in some people, and because of its metallic color, there may be an aesthetic problem. In contrast, zirconia has good biocompatibility, little concern about allergic reactions, and good aesthetics because it is white. Zirconia is a heat-resistant material, has a stable tetragonal crystal structure by high-temperature treatment, and its resistance to acids and alkalis has also been evaluated. Also, Y-TZP (yttria-stabilized tetragonal zirconia) has a resistance exceeding 900 MPa. From these points, zirconia has superior properties compared to ceramic materials and dental metal alloys. Zirconia is chemically stable, and its high biocompatibility with cells and tissues has been demonstrated in in vitro and in vivo tests, and no side effects such as inflammation, deformation, and immune reactions have been reported. Also, in zirconia culture, good colony formation, differentiation, and proliferation of osteoblasts and fibroblasts have been confirmed. It has also been found that surface treatment inside the bone where zirconia is implanted into the bone expands the contact area with the bone, increases the impregnation of liquid, and improves the bonding with cells.

[0040] Here, FIG. 3 is a principal stress line analysis diagram by the finite element method, and FIG. 4 is a von Mises stress distribution analysis diagram. From FIG. 3, it can be seen that when stress is applied to the top surface 21 of the artificial tooth root 10, three orthogonal principal stresses are generated in a uniform and repetitive direction on the outer surface of the artificial tooth root 10. Also, in FIG. 4, the darker the color, the higher the stress value, and it can be seen that when stress is applied to the top surface 21 of the artificial tooth root 10, a uniform and appropriate mechanical stimulus is applied to the outer periphery of the artificial tooth root 10. Since the shape of the artificial tooth root 10 is a continuous spherical shape formed by large vertically-connected spheres with unevenness, repetitive fluid (bone marrow blood) flow occurs due to the vibrational movement during chewing (occlusion). This fluid flow is transmitted in a path approximated to the principal stress lines and becomes a flow current. The flow potential in this flow current triggers the genes of undifferentiated mesenchymal cells in the bone marrow, and periodontal tissues such as cementum (fibrous bone), periodontal fiber tissue, periodontal microvascular group, and alveolar bone proper including the periodontal ligament are formed. That is, due to the shape of the artificial tooth root 10, orthogonal principal stresses are applied in a repetitive direction to the entire area around the artificial tooth root 10, and a uniform mechanical stimulus is applied, so it can be understood that hematopoiesis and osteogenesis are promoted.

[0041] (Second Embodiment) FIG. 5 is a view for explaining the shape of the artificial tooth root 10-2 according to the second embodiment of the present invention, which is (a) a front view, (b) a left side view, (c) a right side view, (d) a rear view, (e) a plan view, and (f) a bottom view. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The artificial tooth root 10-2 of this embodiment is designed for patients with a small jaw and has a thinner shape than that of the first embodiment. The artificial tooth root 10-2 is composed of a crown portion 20 and a root portion 30, and is formed in a columnar shape having an axis P as a whole. The root portion 30 includes spheres 31 and 32 arranged vertically on the axis P. As shown in (c), in this embodiment, the diameter D31 of the first sphere 31 and the diameter D32 of the second sphere 32 are substantially the same. As shown by the broken lines in (b), the boundary portions 38 and 38' are formed to have the curved surface shape of the spherical surfaces of the virtual spheres S1 and S2, and the root tip 39 has the spherical shape of the second sphere 32. As shown in (d), the diameter D10 of the artificial tooth root 10-2 is the diameter D31 of the first sphere 31. The determination diagnosis of the size of the artificial tooth root 10-2, that is, the major axis L10 and the diameter D10, is performed by measurement based on a CT image, and it is designed to be made to order according to the state of the patient's bone. The artificial tooth root 10-2 is also formed as a zirconia molded product.

[0042] (Third Embodiment) FIG. 6 is a diagram for explaining the shape of the artificial tooth root 10-3 according to the third embodiment of the present invention, which is (a) a front view, (b) a left side view, (c) a right side view, (d) a rear view, (e) a plan view, and (f) a bottom view. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The artificial tooth root 10-3 of this embodiment is designed for a patient with a large jaw, and is designed in a shape in which the major axis L10 of the first embodiment is extended (the number of spheres is increased). The artificial tooth root 10-3 also includes a crown portion 20 and a root portion 30, and is formed in a columnar shape having an axis P as a whole. The root portion 30 includes first sphere 31, second sphere 32, and third sphere 33 arranged vertically on the axis P. The diameter D33 of the third sphere 33 is formed to be slightly smaller than the diameter D32 of the second sphere. As shown by the broken lines in (b), the boundary portions 38, 38' are formed in a spherical surface shape of the spherical surfaces of the virtual spheres S1, S2, and the second sphere 32 and the third sphere 33 are adjacent to each other such that the vertices (the lower vertex V40 of the second sphere 32 and the upper vertex V41 of the third sphere 33) are in contact with each other on the axis P. The boundary portion 38'' between the second sphere 32 and the third sphere 33 is formed in a spherical surface shape of the spherical surface of a virtual sphere S3 that contacts the second sphere 32 and the third sphere 33 and has a diameter approximately the same as the diameter D33 of the third sphere 33. The root tip 39 of the artificial tooth root 10-3 has a spherical surface shape of the third sphere 33, and the diameter D10 of the artificial tooth root 10-3 is the diameter D31 of the first sphere 31. The determination diagnosis of the size of the artificial tooth root 10-3, that is, the major axis L10 and the diameter D10, is performed by measurement using a CT image, and it is designed to be made to order according to the state of the patient's bone. The artificial tooth root 10-3 is also formed as a molded product of zirconia.

[0043] (Fourth Embodiment) FIG. 7 is a diagram for explaining the shape of the artificial tooth root 10-4 according to the fourth embodiment of the present invention, and is (a) a front view, (b) a left side view, (c) a right side view, (d) a rear view, (e) a plan view, and (f) a bottom view. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The fourth embodiment is another idea of extending the major axis L10 of the first embodiment. In the first embodiment, the apex of the sphere was in contact at the boundary portions 38, 38'. However, in the artificial tooth root 10-4 of this embodiment, the shape allows the separation of the apexes at the boundary portions 38, 38'. As shown in (b), in the artificial tooth root 10-4, the lower apex V35 of the first sphere 31 and the upper apex V36 of the second sphere 32 are arranged on the axis P with a distance d therebetween. The boundary portion 38 between the first sphere 31 and the second sphere 32 is formed in the curved surface shape of the spherical surface of the virtual sphere S1. The separation distance d is at most equal to the radius d31 of the first sphere 31. The artificial tooth root 10-4 is also formed as a molded product of zirconia.

[0044] On the other hand, FIG. 8 is a diagram showing a comparative example with the artificial tooth root 10-4. The artificial tooth root 100 of the comparative example has a shape formed with the distance d exceeding the radius d31 of the first sphere 31. In the artificial tooth root 100 of the comparative example, it becomes impossible to connect the boundary portion 38 with the spherical surface of a virtual sphere having the same size as the first sphere 31 or the second sphere 32, and the boundary portion 38 becomes linear. The boundary portion 38 generates a different flow from the spherical unevenness formed by the spheres 31, 32 and the boundary portion 38', and as a result, an appropriate mechanical stimulus is not generated in the vicinity of the boundary portion 38, and blood stasis occurs in the vicinity of the root tip 39. Therefore, when adopting the shape of the artificial tooth root 10-4, it is preferable to set the separation distance d of the spheres to be equal to or less than the radius d31 of the first sphere 31.

[0045] (Case) Figures 9 to 11 show actual cases of defect repair. Figure 9 is an X-ray photograph on the day after surgery, Figure 10 is an X-ray photograph 5 months after the surgery, and Figure 11 is an X-ray photograph 12 months after the surgery. For the patient, local anesthesia was used in combination with intravenous sedation, and an implantation socket 9 was formed using drills with diameters of 3.5 mm and 3.8 mm. An artificial tooth root 10-2 shown in the second embodiment, designed with a diameter D10 = 4.1 mm and a major axis L10 = 11.0 mm, was implanted. In Figure 9 immediately after the surgery, no alveolar hard line is confirmed around the artificial tooth root 10-2, but in Figure 10 5 months after the surgery, a clear alveolar hard line-like white line can be confirmed. In Figure 11 12 months after the surgery, the alveolar hard line-like white line is clearer, and it can be confirmed that the periodontal pocket is also normal. Even in the examination at one and a half years after the surgery, the alveolar hard line-like white line and the periodontal tissue were as good as in Figure 11, and it was reported that the patient had no occlusal pain and felt sufficient tooth sensation.

[0046] (Function and Effect) As described above, according to the artificial tooth roots 10 and the like shown in the first to fourth embodiments, since they have a shape that forms a continuous and uneven spherical shape by means of the vertically connected spheres, repeated flow of liquid (bone marrow blood) is likely to occur, and the formation of cementum (fibrous bone), periodontal fiber tissue, periodontal microvascular group, alveolar bone proper, etc., including the periodontal ligament, is promoted. Hematopoiesis and osteogenesis are conjugated, and the formation of the periodontal ligament is promoted, so that the immune system associated with the periodontal ligament (self-cleaning action by fenestrated blood vessels, capture and phagocytosis of white blood cells) can act quickly. By regenerating and restoring periodontal tissue similar to that of natural teeth, the patient can receive sensory input during chewing and various oral reflexes associated with the stimuli applied to the teeth can be induced, so it is considered that the patient's postoperative discomfort can be alleviated. Furthermore, since the treatment can make the patient feel tooth sensation through the regeneration of periodontal tissue including the periodontal ligament, it can be provided as a treatment beneficial for extending human healthy life and preventing dementia.

[0047] In addition, for the artificial dental roots 10 shown in the embodiments, regardless of the dental arch, the root apex 39 is formed in a spherical shape of a sphere. That is, the root apex 39 is formed in a spherical shape at any location of the maxillary anterior teeth, mandibular anterior teeth, canine artificial dental roots, maxillary and mandibular premolars, maxillary molars, and mandibular molars in the dental arch. This is because importance is attached to the repetitive flow of fluid (bone marrow blood). Also, from the perspective of molding the artificial dental root 10, there is no trouble in changing the design of the shape of the root apex 39 to match the shape of the natural tooth. If the state of the patient's bone is measured by a CT image and a suitable diameter D10 and major axis L10 are determined, there is an advantage that it can be easily designed.

[0048] As described above, the preferred embodiments and modification examples of the present invention have been described. However, it is possible to modify and combine these based on the knowledge of those skilled in the art, and such forms are also included in the scope of the present invention.

Explanation of Reference Numerals

[0049] 10... artificial dental root, 20... tooth crown part, 21... top surface of tooth crown part, 22... upper part of tooth crown part, 23... root part of tooth crown part, 30... tooth root part, 31... first sphere, 32... second sphere, 33... third sphere, 38, 38', 38''... boundary part, 39... root apex, V24, V34, V35, V36, V40, V41... apex, P... axis

Claims

1. A columnar shape having a crown portion at one end and a root tip at the opposite end, wherein between the crown portion and the root tip, there are provided two or more vertically aligned spheres, and the boundary portions of the spheres are formed into a smooth curved surface shape that is concave toward the axial center side. An artificial tooth root characterized by the above.

2. The artificial tooth root according to Claim 1, characterized in that the base portion of the crown portion has a hemispherical shape, and the boundary portion between the base portion and the spheres is also formed into a smooth curved surface shape that is concave toward the axial center side.

3. The artificial tooth root according to Claim 1, characterized in that the root tip is formed of the spheres regardless of the dentition.

4. The artificial tooth root according to Claim 1, characterized in that the boundary portion is in contact with the adjacent spheres and has a curved surface shape of a spherical surface of a virtual sphere having substantially the same diameter as any one of the spheres.

5. The maximum outer diameter of the crown portion is made the same as the diameter of the sphere adjacent to the crown portion, and the artificial tooth root according to Claim 1, characterized in that the diameter of the spheres is formed to gradually decrease as the distance from the crown portion increases.

6. The artificial tooth root according to Claim 1, characterized in that the maximum outer diameter of the crown portion and the diameters of the spheres are all made the same.

7. The artificial tooth root according to Claim 2, characterized in that the spheres and the hemisphere are arranged such that the vertices in the arrangement direction are in contact.

8. The artificial tooth root according to Claim 2, characterized in that the spheres and the hemisphere are arranged such that the vertices in the arrangement direction are separated by a distance equal to or less than the radius of any one of the spheres.

9. The artificial tooth root according to Claim 1, characterized in that the artificial tooth root is made of zirconia.

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