WO2009072764A1

WO2009072764A1 - Dental implant

Info

Publication number: WO2009072764A1
Application number: PCT/KR2008/006827
Authority: WO
Inventors: Ji Hoon Yoon; Hyeon Cheol Jeong; Ju Suk Kim; Tae Gwan Eom
Original assignee: Osstem Implant Co Ltd
Current assignee: Osstem Implant Co Ltd
Priority date: 2007-12-06
Filing date: 2008-11-19
Publication date: 2009-06-11
Anticipated expiration: 2010-06-06
Also published as: KR100860356B1

Abstract

The present invention relates to a dental implant having a plurality of axis portions thereby in use being capable of preventing an abrupt increase in an amount of bone compression through the plurality of axis portions, dispersing stress according to a gradual increase in placement torque, and simultaneously obtaining a proper initial fixing force, and more particularly, to a dental implant having first through third axis portions formed on the exterior circumferential surface thereof, capable of adjusting a bone contacting area, dispersing stress, gradually increasing an area used to compress bone between the first through third axis portions, and preventing an amount of bone compression from being abruptly increased, thereby facilitating placement of the dental implant and increasing an initial fixing force.

Description

DENTAL IMPLANT

Technical Field

[1] The present invention relates to a dental implant having a plurality of axis portions capable of preventing an abrupt increase in an amount of bone compression through the plurality of axis portions, dispersing stress according to a gradual increase in placement torque, and simultaneously obtaining a proper initial fixing force, and more particularly, to a dental implant in the shape of a projection portion having first through third axis portions formed on the exterior circumferential surface thereof, capable of adjusting a bone contacting area, dispersing stress, gradually increasing an area used to compress bone between the first through third axis portions, and preventing an amount of bone compression from being abruptly increased, thereby facilitating placement of the dental implant and increasing an initial fixing force. Background Art

[2] Dental implants are used as alternatives to treat lost human body parts, and in particular refer to the planting of an artificial tooth through a dental service. A dental root made of titanium having no rejection to human body is planted in an area of a lost tooth, an artificial tooth is fixed thereon, and dental functions are restored so as to replace the lost tooth. Although a tooth or bone around a dental prosthesis or a denture is likely to become damaged through the passage of time, a dental implant prevents surrounding tooth tissue from being damaged. Dental implants have the same function and shape as natural teeth and do not cause decay and are semi-permanent. Dental implants use a screw type fixture having a screw thread on the exterior circumferential surface of its main body, which is used as a fixing member for fixing a dental or orthopedic prosthesis to a bone. Owing to improvements in medical technology and surgical performance, dental implanting surgery has become more common on account of its increasing success, and surgery convenience has become an important factor.

[3] Conventional dental implants have screw threads on the exterior cylindrical axis and a connecting portion on the exterior or interior cylindrical axis to a dental prosthesis. The conventional screw threads provide convenience in placing a dental implant, and maintain an alveolar bone by properly dispersing stress to the alveolar bone after Os- seointegration. The conventional screw threads are classified into two types: (i) a screw thread having an upper portion and a lower portion of the same size as shown in FIG. 1, and (ii) a screw thread having an upper portion and a lower portion larger than the upper portion as shown in FIG. 2.

[4] A dental implant having the conventional screw thread shown in FIG. 1 provides convenience of placement; however it is difficult to maintain an alveolar bone due to a bad stress dispersion effect after Osseointegration. A dental implant having the conventional screw thread shown in FIG. 2 has a good stress dispersion effect; however it is not tightly placed on the upper portion of the screw thread due to an abrupt increase in the amount of compressing the alveolar bone (an amount of bone compression) during a process of placing the dental implant from the lower portion to the upper potion. In more detail, one of the biggest problems that occurs when conventional dental implants are used is the abrupt increase in the amount of bone compression. The amount of bone compression is an amount of bone that is compressed by an tapered portion of a dental implant when the dental implant is placed on an alveolar bone. An abrupt change in shape of the tapered portion increases the amount of bone compression, which reduces an initial fixing force of an upper portion of a screw thread and thus hinders Osseointegration.

[5] The dental implant having the conventional screw thread shown in FIG. 1 has an initially increasing torque due to repeated rotations and then the torque gradually reduces, and thus initial fixing force is low. The dental implant having the conventional screw thread shown in FIG. 2 is not properly fixed due to an abrupt increase in torque when the screw thread of the upper portion is placed. Disclosure of Invention Technical Problem

[6] The present invention provides a dental implant having a projection portion on a cylindrical exterior circumferential surface, providing convenience of placement of the dental implant, having an appropriate initial fixing force so as to prevent a failure in bone adhesion due to a minute motion, and having a sufficient stress dispersion capability after Osseointegration.

[7] The present invention also provides a dental implant having a plurality of axis portions, dispersing collected stress of an upper portion to a lower portion, facilitating Osseointegration, and increasing initial fixing force, since a conventional dental implant having the same size of screw threads does not properly disperse stress after a bone adhesion and thus fixing force is reduced, which prevents Osseointegration.

[8] The present invention also provides a dental implant capable of increasing convenience of placement and initial fixing force, since torque of a conventional dental implant having a uniform projection portion initially increases repeated rotation and then gradually decreases, and thus initial fixing force is low, and a conventional dental implant having a small screw thread of an upper portion and a great screw thread of a lower portion is not properly placed due to an abrupt increase in torque when the screw thread of the upper portion is placed.

[9] The present invention also provides a dental implant capable of preventing an abrupt increase in torque due to a gradual increase in a cross-section area per rotation from a first axis portion to a third axis portion, which gradually increases the torque, and allows the obtaining of a proper initial fixing force.

[10] The present invention also provides a dental implant capable of properly dispersing a mesh force to an alveolar bone by small screw threads of second and third axis portions in order to maintain homeostasis when a force is properly applied to a human bone. Technical Solution

[11] According to an aspect of the present invention, there is provided a dental implant comprising three or more axis portions having a roughed cross-section on a cylindrical exterior circumferential surface and disposed in a vertical arrangement,

[12] wherein a plurality of projection portions and a plurality of groove portions are formed on the exterior circumferential surface of each of the three or more axis portions, and the numbers of the plurality of projection portions and the plurality of groove portions within the same axial distance sequentially increase from a lower axis portion to an upper axis portion. Advantageous Effects

[13] The present invention provides a dental implant having a projection portion on the cylindrical exterior circumferential surface, providing convenience of placement of the dental implant, having an appropriate initial fixing force so as to prevent a failure in a bone adhesion due to a minute motion, and having a sufficient stress dispersion capability after the Osseointegration.

[14] The present invention also provides a dental implant having a plurality of axis portions, dispersing collected stress of an upper portion to a lower portion, facilitating Osseointegration, and increasing initial fixing force, since a conventional dental implant having the same size of screw threads does not properly disperse stress after a bone adhesion and thus fixing force is reduced, which prevents Osseointegration.

[15] The present invention also provides a dental implant capable of increasing convenience of placement and initial fixing force, since torque of a conventional dental implant having a uniform projection portion is initially increased by repeated rotation and then gradually reduces, and thus initial fixing force is low, and a conventional dental implant having an upper portion with a small screw thread and a lower portion with a large screw thread is not properly placed due to an abrupt increase in torque when the screw thread of the upper portion is placed.

[16] The present invention also provides a dental implant capable of preventing an abrupt increase in torque due to a gradual increase in a cross-section area per rotation from a first axis portion to a third axis portion, which gradually increases the torque, and allows the obtaining of a proper initial fixing force. [17] The present invention also provides a dental implant capable of properly dispersing a mesh force to an alveolar bone by small screw threads of second and third axis portions in order to maintain homeostasis when a force is properly applied to a human bone.

Description of Drawings [18] FIG. 1 is an elevational diagram illustrating a conventional dental implant having the same screw threads formed on upper and lower portions thereof; [19] FIG. 2 is an elevational diagram illustrating a conventional dental implant having different screw threads formed on upper and lower portions thereof; [20] FIG. 3 is an elevational diagram illustrating a dental implant having a plurality of axis portions according to an embodiment of the present invention; [21] FIG. 4A is a detailed diagram illustrating a plurality of projection portions of a first axis portion according to an embodiment of the present invention; [22] FIG. 4B is a detailed diagram illustrating a plurality of projection portions of a second axis portion according to an embodiment of the present invention; [23] FIG. 4C is a detailed diagram illustrating a plurality of projection portions of a third axis portion according to an embodiment of the present invention; [24] FIG. 5 is an elevational diagram illustrating a dental implant comprising a plurality of groove portions having different diameters according to an embodiment of the present invention; [25] FIG. 6 is an elevational diagram illustrating a dental implant according to another embodiment of the present invention; [26] FIG. 7 is a diagram illustrating a dental implant placed in an alveolar bone according to an embodiment of the present invention; [27] FIG. 8 is a diagram illustrating an amount of bone compression when a dental implant is placed in an alveolar bone according to an embodiment of the present invention; and [28] FIG. 9 is an elevational diagram illustrating a dental implant according to another embodiment of the present invention.

Best Mode [29] Hereinafter, the present invention will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. [30] FIG. 3 is an elevational diagram illustrating a dental implant 10 having a plurality of axis portions according to an embodiment of the present invention. FIG. 4A is a detailed diagram illustrating a plurality of projection portions of a first axis portion 100 according to an embodiment of the present invention. FIG. 4B is a detailed diagram il- lustrating a plurality of projection portions of a second axis portion 200 according to an embodiment of the present invention. FIG. 4C is a detailed diagram illustrating a plurality of projection portions of a third axis portion 300 according to an embodiment of the present invention. FIG. 5 is an elevational diagram illustrating a dental implant comprising a plurality of groove portions having different diameters according to an embodiment of the present invention. FIG. 6 is an elevational diagram illustrating a dental implant according to another embodiment of the present invention. FIG. 7 is a diagram illustrating a dental implant placed in an alveolar bone according to an embodiment of the present invention. FIG. 8 is a diagram illustrating an amount of bone compression when a dental implant is placed on an alveolar bone according to an embodiment of the present invention.

[31] Referring to FIGS. 3 through 5, the dental implant 10 comprises three or more projection portions which each spiral around a cylindrical exterior circumferential surface. The different projection portions have different cross-sections of bone compression per rotation. The first axis portion 100, the second axis portion 200, and the third axis portion 300 are sequentially disposed from a lower portion to an upper portion of the dental implant 10 in correspondence with the different cross-sections of the projection portions. An uppermost portion 19 is disposed on the upper side of the third axis portion 300. In use, the dental implant 10 having the plurality of axis portions exerts no abrupt increase in torque since the cross-sections of the first axis portion 100, the second axis portion 200, and the third axis portion 300 gradually increase, and obtains a proper initial fixing force due to a gradual increase in bone compression. The second axis portion 200 and the third axis portion 300 have a low concentration of projection portions, which increase a bone contact area, thereby facilitating stress dispersion after bone adhesion.

[32] The first axis portion 100 is a lowest portion of the dental implant 10 where the alveolar bone is first placed as shown in FIG. 3. The thickness of the first axis portion 100 reduces in a downward direction. The first axis portion 100 comprises a cutting edge 11, a plurality of first projection portions 110, and a plurality of first groove portions 130.

[33] The cutting edge 11 is formed by cutting a lower portion of the first axis portion 100 in an axial direction when the dental implant 10 is placed in the alveolar bone that is perforated by drilling. The cutting edge 11 performs a self-tapping function to form a female screw thread on the alveolar bone. In more detail, referring to FIG. 6, if the dental implant 10 is buried in a groove A that is formed in a bone tissue on which the dental implant 10 is placed and has a smaller diameter than the dental implant 10, the cutting edge 11 forms the female screw thread on the interior circumferential surface of the groove A by which placement is guided. [34] The first projection portions 110, which are formed on a tapered area of the exterior circumferential surface of the first axis portion 100, increase a contact area so as to enhance a firm coupling force to the alveolar bone, and realize a stable dental implant so as to support shear stress. In this regard, the first projection portions 110 are continuously formed along the exterior circumferential surface of the first axis portion 100 as shown in FIG. 3, which forms screw threads so as to rotatably place the dental implant 10 like a screw type fixture. However, the first projection portions 110 formed in screw threads shown in FIG. 3 are a preferred embodiment and, the present invention is not limited thereto. Any changes in form may be made if the first projection portions 100 increase the contact surface with the alveolar bone, support the shear stress, and implement a firm coupling force.

[35] The first groove portions 130 are formed on the tapered area of the exterior circumferential surface of the first axis portion 100 between the first projection portions 110. The dental implant 10 is firmly adhered to an alveolar bone of the first groove portions 130 because of the structure of the first groove portions 130, which increases the contact area, thereby increasing a coupling force between the dental implant 10 and the alveolar bone. Like the first projection portions 110, the first groove portions 130 may be formed as screw grooves on the exterior circumferential surface of the first axis portion 100. However, since this is just a preferred embodiment, any changes in the first groove portions 130 may be made therein without departing from the spirit and scope of the present invention.

[36] The second axis portion 200 is a specific exterior circumferential surface of the dental implant 10 including the tapered portion formed continuously from the upper portion of the first axis portion 100, which increase a bone contact area, thereby increasing bone adhesion and dispersing stress in the same manner as the first axis portion 100. The second axis portion 200 comprises a plurality of second projection portions 210 and a plurality of groove portions 230.

[37] The second projection portions 210 are formed on an tapered portion of the exterior circumferential surface of the second axis portion 200, which increases bone adhesion, thereby facilitating stress dispersion in the same manner as the first projection portions 110 of the first axis portion 100. Also, the second projection portions 210 are formed as screw threads continuing on from the exterior circumferential surface of the second axis portion 200, thereby increasing convenience of placement, like the first projection portions 110 of the first axis portion 100. The second projection portions 210 may comprise a plurality of second small projection portions 211 on the floor thereof. The second small projection portions 211 may be used to disperse collected stress in the second axis portion 200 by allowing a double screw thread structure to be used.

[38] The groove portions 230 are formed in the tapered area of the exterior circum- ferential surface of the second axis portion 200, which correspond to the first groove portions 130 of the first axis portion 100. Therefore, the groove portions 230 increase the bone contact area, thereby dispersing stress. If the groove portions 230 are in the form of screw grooves, a screw type placement is possible, thereby increasing convenience of placement. The second groove portions 230 comprise a plurality of second small groove portions 231 for preventing stress from being collected and dispersing stress to another axis portion.

[39] Referring to FIGS. 3, 4A, and 4B, a distance between the second groove portions 230 of the second axis portion 200 including the second projection portions 210 and the second groove portions 230 may be the same as a distance wl between the first groove portions 130 of the first axis portion 100 including the first projection portions 110 and the first groove portions 130. Therefore, when the same distance is maintained between screw grooves, continuity of screws and constant lead are maintained, which does not damage another alveolar bone and facilitates convenience of placement of the dental implant 10. A distance between the second small groove portions 231 is smaller than the distance wl between the first groove portions 130, which reduces an abrupt increase in an amount of bone compression, thereby easily obtaining initial fixing force and realizing convenience of placement of the dental implant 10. A distance w3 between the third groove portions 330 of the third axis portion 300 shown in FIG. 4C may be the same as the distance wl between the first groove portions 130 and the distance w2 between the second groove portions 230. Thus, the first through third axis portions 100, 200, and 300 maintain the same distances wl, w2, and w3, so that the same pitch and lead can be maintained, thereby reducing damage of bone when the dental implant 10 is placed.

[40] Diameters of the second groove portions 230 of the second axis portion 200 may be the same as those of the first groove portions 330 of the first axis portions 100 or may gradually increase.

[41] The third axis portion 300 is an upper portion of the entire main body that is continuously formed from the upper portion of the second axis portion 200. When the dental implant 10 is completely placed in the alveolar bone, the third axis portion 300 may be disposed on a cortical bone. The third axis portion 300 comprises the third projection portions 310 and the third groove portions 330. Although diameters of the third groove portions 330 of the third axis portion 300 may be the same as those of some of the second groove portions 230 of the second axis portions 100, the diameters of the third groove portions 330 of the third axis portion 300 may not be the same as those of the other second groove portions 230 of the second axis portions 100. Thus, stress may be uniformly dispersed on the first through third axis portions 100, 200, and 300, thereby providing convenience of placement as a screw type dental implant. In this case, referring to FIG. 8, a plurality of projection portions and groove portions formed on an axis portion of an upper side of the dental implant may be smaller than those formed on an axis portion of a lower side thereof, in order to gradually increase the amount of bone compression when in use, thereby gradually increasing a meshing force and providing a firm coupling force between the dental implant 10 and bone.

[42] The third projection portions 310 are formed on a tapered area of the exterior circumferential surface of the third axis portion 300 so as to correspond to the first projection portions 110 and the second projection portion 210, thereby increasing an area contacting the alveolar bone, and increasing coupling fixing force. The third projection portions 310 may be formed in screw threads on the exterior circumferential surface of the third axis portion 300 like the first and second projection portions 110 and 210, which facilitates convenience of placement of the dental implant 10, and reduces damage of bone, thereby obtaining a firm coupling force of the dental implant 10. The third projection portions 310 may comprise third small projection portions 311. The number of the third small projection portions 311 formed on the upper portion of the third projection portions 310 is required to be greater than that of the second small projection portions 211 formed on the upper portion of the second projection portions 210, which prevents the amount of bone compression from being abruptly increased, so that when the dental implant 10 is placed using a female screw thread of the alveolar bone compressed by the first projection portions 110, the alveolar bone is further compressed by the second projections portions 210 and the second small projection portions 211, and is further compressed by the third projection portions 310 and the third small projection portions 311, thereby gradually increasing the amount of bone compression and facilitating stability of placement.

[43] The third groove portions 330 are formed in the tapered portion of the exterior circumferential surface of the third axis portion 300 and correspond to the third projection portions 310. The third projection portions 330 form screw grooves when the third projection portions 310 are formed in screw threads or the third small projection portions 311 are formed in screw threads. In this regard, the third groove portions 330 may be disposed between the third small projection portions 311, and may have diameters greater than those of the first and second groove portions 130 and 230, in order to gradually increase the amount of bone compression.

[44] Hereinafter, a description of a structure involving the first through third projection portions 110, 210, and 310 having screw thread and screw groove profiles will now be described. This structure provides convenience of placement and reduces damage of bone due to the placement. A 'lead' means a travel distance of a screw in an axial direction during a rotation. A single screw generally has the same lead and pitch, whereas a multi-screw thread or a complicated screw thread does not have the same lead and pitch. Thus, with regard to a screw tooth profile, it is not easy to obtain a lead by measuring a distance between pitches or peaks. Therefore, each screw tooth profile determines the lead. Referring to FIGS. 4A, 4B, and 8, the first and third projection portions 110, 210, and 310 and the first through third groove portions 130, 230, and 330 form screw thread and screw groove profiles that are formed in a continuous fashion on the exterior circumferential surfaces of the first through third axis portions 100, 200, and 300. The first through third axis portions 100, 200, and 300 have the distances wl, w2, and w3, respectively, between the first through third groove portions 130, 230, and 330 that are screw grooves, as shown in FIGS. 4A and 4B, so that the amount of bone compression gradually increases as shown in FIG. 8. When the distances wl, w2, and w3 are the same, leads are the same. Therefore, a lead of the screw tooth profile of the dental implant 10 is determined according to the distances wl, w2, and w3, respectively, between the first through third groove portions 130, 230, and 330 shown in FIGS. 4A, 4B, and 8. If the distances wl, w2, and w3 between grooves are the same, the screw tooth profile has the same lead, which facilitates placing the dental implant 10. Since a next screw thread passes through a screw thread that is the same projection portion, damage of the alveolar bone is minimized, thereby finally preventing dissociations between bones, facilitating Osseointegration, and implementing a firm bone fixing force.

[45] Referring to FIG. 5, the diameters of the first through third axis portions 100, 200, and 300 may increase toward the third axis portion 300. When the diameters of the first through third axis portions 100, 200, and 300 are Dl, D2, and D3, respectively, the diameters of first through third groove portions 130, 230, and 330 may gradually increase upward so as to satisfy that D3>D2>D1, thereby increasing a mesh force due to a 'wedge effect' on account of the increase in the diameters.

[46] Referring to FIG. 6, a groove 400 may be formed in the bottom of the third axis portion 300 as a portion connecting the second axis portion 200 and the third axis portion 300. Since the groove 400 performs the self-tapping function that is the same as the cutting edge 11, the groove 400 forms a female screw on the alveolar bone and guides placement of the dental implant. The groove 400 may be formed over below part of the third axis portion 300 and the upper part of the second axis portion 200. The groove 400 is used to prevent an abrupt increase in placement torque caused by different screw threads formed on the first through third axis portions 100, 200, and 300.

[47] A detailed description of how to use and operate the dental implant 10 having the plurality of axis portions will now be given with reference to FIGS. 7 and 8.

[48] The projection portions are formed on the cylindrical exterior circumferential surface of the dental implant 10 according to the principle of screws. The dental implant 10 is placed on an area of a tooth that is to be restored by drilling the area by using a drill and being rotated by using a dental surgical tool. A curvature portion is formed on the cylindrical exterior circumferential surface of the dental implant 10. A connection portion connecting an abutment is formed on the exterior surface or interior surface of the dental implant 10 or the abutment is integrally formed on the dental implant 10. The dental implant 10 has three or more cross-sections of the curvature portion. The number of curvature portions of the second axis portion 200 is one or more than that of curvature portions of the first axis portion 100. The number of curvature portions of the third axis portion 300 is one or more than that of the curvature portions of the second axis portion 200. The boundaries of the first through third axis portions 100, 200, and 300 are formed in combination of a truncated conical end portions or cylindrical end portions. The curvature portions of the first through third axis portions 100, 200, and 300 may have a variety of combinations of uniform or random depths. The first through third axis portions 100, 200, and 300 may have one curvature portion, two curvature portions, and three curvature portions, respectively, and may be adjacent to each other. The depth of the curvature portions of the second and third axis portions 200 and 300 is smaller than that of the first axis portion 100. The first through third axis portions 100, 200, and 300 have at least one curvature portion shape having the same pitch during one rotation.

[49] With regard to the operation of the dental implant 10 having the plurality of axis portions, referring to FIG. 7, the dental implant 10 is screwed in an alveolar bone 3 perforated by drilling. A diameter A of a groove formed in the alveolar bone 3 may be slightly smaller than that of the dental implant 10 so as to form female screws on the alveolar bone 3.

[50] When the dental implant 10 is placed on the alveolar bone 3 while rotating around a placement axis X, female screws are sequentially formed on the alveolar bone 3 shown in FIG. 8. The dental implant 10 is self- tapped by the groove 400 according to the first projection portion 110 of the first axis portion 100 and a large female screw thread is first formed on the alveolar bone 3 as shown in FIG. 8A.

[51] Referring to FIG. 8B, the second axis portion 200 follows the first axis portion 100, so that an amount Sl of bone compression increases for the different projection portions since a full diameter of the first axis portion 100 is smaller than that of the second axis portion 200.

[52] Referring to FIG. 8C, since the third axis portion 300 follows the second axis portion

200, the third projection portions 310 of the third axis portion 300 are smaller than the second projection portions 210 of the second axis portion 200, and a full diameter of the third axis portion 300 is greater than that of the second axis portion 200, so that the amount of bone compression is increased by S2. The dental implant 10 is completely placed on the alveolar bone 3 so that the amount of bone compression gradually increases.

[53] If the dental implant 10 comprises an upper portion and a lower portion, the amount of bone compression abruptly increases, which applies pressure to the alveolar bone 3, reduces a mesh force, and causes dissociation between bones. Therefore, according to the present invention, the amount of bone compression of the dental implant 10 gradually increases from the first axis portion 100 to the third axis portion 300, which does not abruptly increase torque, and obtains a proper initial fixing force by the gradual bone compression. The small projection portions of the second and third axis portions 200 and 300 disperse stress after adhesion of bone.

[54] Meanwhile, the same effect may be obtained from a dental implant having a curved cross-section on a cylindrical exterior circumferential surface and three or more axis portions formed vertically, projection portions and groove portions formed on the exterior circumferential surface of the axis portions having cross-sections which gradually reduce from the axis portion in the bottom to the axis portion in the top. When the plurality of axis portions are first through third axis portions, groove portions having different diameters may be alternately disposed in the second axis portion, and the numbers of the projection portions and the groove portions may increase in an upward direction. The groove portions having different diameters may be formed on the first or third axis portion.

[55] FIG. 9 is an elevational diagram illustrating a dental implant according to another embodiment of the present invention. Referring to FIG. 9, the third axis portion 300 may comprise an upper portion 300' and a lower portion 300". Diameters of projection portions of the upper portion 300' are maintained constant in an axial direction, whereas diameters of projection portions of the lower portion 300" gradually increase upward in the axial direction. In more detail, a straight line connecting the diameters of adjacent ones of projection portions of the lower portion 300" is inclined at an angle of θ with regard to an axis parallel to a rotation axis, θ may be from about 0.5 ° to about 1 °. In this case, when the dental implant is placed from the second axis portion 200 to the third axis portion 300, an amount of bone compression gradually increases, thereby satisfying the characteristics of placement as a whole.

[56] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

[1] A dental implant comprising three or more axis portions having a roughed cross- section on a cylindrical exterior circumferential surface and disposed in a vertical arrangement, wherein a plurality of projection portions and a plurality of groove portions are formed on the exterior circumferential surface of each of the three or more axis portions, and the numbers of the plurality of projection portions and the plurality of groove portions within the same axial distance increase from a lower axis portion to an upper axis portion.

[2] The dental implant of claim 1, wherein the three or more axis portions comprise first, second, and third axis portions sequentially from the bottom, wherein the numbers of the plurality of projection portions and the plurality of groove portions of the second axis portion within the same axial distance are one or more than those of the first axis portion, and wherein the numbers of the plurality of projection portions and the plurality of groove portions of the third axis portion within the same axial distance are one or more than those of the second axis portion.

[3] The dental implant of claim 2, wherein diameters of the plurality of projection portions of each of the first, second, and third axis portions are maintained constant or gradually increase upward

[4] The dental implant of claim 2, wherein diameters of the plurality of groove portions of each of the first, second, and third axis portions gradually increase upward.

[5] The dental implant of claims 2, wherein, when a lead is taken to mean an axial travel distance during one rotation, the numbers of the plurality of projection portions of the first, second, and third axis portions per lead are one, two, and three, respectively.

[6] The dental implant of claim 2, wherein the first, second, and third axis portions are adjacent to each other and are formed in a continuous fashion.

[7] The dental implant of claim 2, wherein the diameters of the plurality of groove portions of the second and third axis portions are greater than those of the first axis portion.

[8] The dental implant of claim 2, wherein the third axis portion comprises a top portion and a bottom portion, wherein diameters of the plurality of adjacent projection portions of the top portion are the same as each other, and wherein diameters of the plurality of projection portions of the bottom portion increase upward.

[9] The dental implant of any one of claims 1 through 8, wherein the plurality of projection portions and the plurality of groove portions have screw thread and screw groove profiles.

[10] The dental implant of claim 9, wherein the first, second, and third axis portions have the same lead so as to facilitate placement of the dental implant, reduce damage of bone, and maintain a firm fixing force.

[11] The dental implant of any one of claims 2 through 8, wherein each of the first, second, and third axis portions further comprises a groove used to form a female screw on analveolar bone by self-tapping.

[12] The dental implant of claim 11, wherein the groove is disposed in the bottom of each of the first, second, and third axis portions.

[13] The dental implant of claim 9, wherein each of the first, second, and third axis portions further comprises a groove used to form a female screw on analveolar bone by self-tapping.

[14] The dental implant of claim 13, wherein the groove is disposed in the bottom of each of the first, second, and third axis portions.

[15] The dental implant of any one of claims 2 through 8, wherein an area in which the plurality of projection portions and the plurality of groove portions are not included is formed in the top of the third axis portion.

[16] A dental implant comprising three or more axis portions having a roughed cross- section on a cylindrical exterior circumferential surface and disposed in a vertical arrangement, wherein a plurality of projection portions and a plurality of groove portions are formed on the exterior circumferential surface of each of the three or more axis portions, and cross-sections of the plurality of projection portions reduce from a lower axis portion to an upper axis portion.

[17] The dental implant of claim 16, wherein the plurality of groove portions having different diameters are alternately disposed on at least one of the three or more axis portions.

[18] The dental implant of claim 16 or 17, wherein the three or more axis portions comprise first, second, and third axis portions sequentially from the bottom, wherein the numbers of the plurality of projection portions and the plurality of groove portions of the second axis portion within the same axial distance are one or more than those of the first axis portion, and wherein the numbers of the plurality of projection portions and the plurality of groove portions of the third axis portion within the same axial distance are one or more than those of the second axis portion.

[19] The dental implant of claim 18, wherein the plurality of groove portions having different diameters are alternately disposed on the second axis portion.

[20] The dental implant of claim 18, wherein diameters of some of the plurality of projection portions of the third axis portion increase upward.