WO2008016205A1

WO2008016205A1 - Internal fixture for dental rescue implant

Info

Publication number: WO2008016205A1
Application number: PCT/KR2006/005394
Authority: WO
Inventors: Kwang Bum Park; Kyoung Ho Ryoo; Seok Kyu Choi; Hae Yong Lee
Original assignee: Megagen Co., Ltd.
Priority date: 2006-07-29
Filing date: 2006-12-12
Publication date: 2008-02-07
Also published as: KR100743181B1

Abstract

An internal fixture for a dental rescue implant includes a main body portion having the diameter of a cross-section of 6 mm to 8 mm relatively larger than the diameter of a cross-section of 5 mm and less of a body portion of a common implant to be directly transplanted in a damaged alveolar bone without a supplement of a bone replacement material, and an inner connection hole formed in an upper end portion of the body portion to be indented to a pre¬ determined depth from an upper surface of the body portion in which a lower end portion of an abutment is inserted to contact each other, and a screw thread formed on an outer surface of the body portion to transplant the body portion in the alveolar bone. At least one connection re¬ inforcing groove is formed on an inner circumferential wall forming the inner connection hole to be indented to a predetermined depth from a surface of the inner circumferential wall and coupled to a connection reinforcing protrusion provided on an outer surface of any of a handpiece connector and the abutment.

Description

Description INTERNAL FIXTURE FOR DENTAL RESCUE IMPLANT

Technical Field

[1] The present invention relates to an internal fixture for a dental rescue implant, and more particularly, to an internal fixture for a dental rescue implant which can be used for a rescue operation, deliver a relatively large amount of a rotation force, and prevent relative rotation of an abutment. Background Art

[2] The word "Implant" originally signifies a replacement to recover damaged or lost human tissues. For the specific field of a dentistry, the implant signifies transplantation of an artificial tooth. That is, the implant is an operation to recover the function of a tooth by placing a dental root made of titanium that shows no rejection symptoms to a human body to replace a lost dental root, in an alveolar bone where a tooth is removed, and fixing an artificial tooth.

[3] In the case of a general dental prosthesis or denture, surrounding teeth and bones are damaged as time passes. In contrast, the implant does not damage surrounding tooth tissues and causes no decayed tooth while providing the same function and shape as a natural tooth. Thus, the implant can be used semi-permanently.

[4] Also, the implant improves not only the restoration of a single lost tooth but also the function of the artificial teeth of partially toothless or completely toothless patients and enhances the aesthetic feature in the restoration of dental prosthesis. Furthermore, the implant can distribute excessive stress applied to the tissues of the surrounding support bone so as to help the stabilization of a row of teeth.

[5] In general, the implant includes a fixture transplanted as an artificial tooth root, an abutment coupled to the fixture, an abutment screw fixing the abutment to the fixture, and an artificial tooth coupled to the abutment. The abutment screw can be omitted according to the type of fixing the abutment to the fixture. That is, when the abutment is directly coupled to the fixture not using the abutment screw, the abutment screw can be omitted.

[6] The operation of the implant configured as above is not always available for every case. The implant operation is available under a condition that a bone tissue existing in a gum, that is, an alveolar bone, has a width and height appropriate for the implant operation. This is because the alveolar bone is to the implant what soil is to a tree. Thus, when the alveolar bone is severely damaged, the implant operation may not be possible. However, except for the case where the alveolar bone is severely damaged so that the implant operation is not possible, the implant operation can be performed by transplanting for a predetermined period an artificial bone replacement material having ingredients such as calcium and phosphorous similar to those of a real bone in replacement of the alveolar bone.

[7] In relation with the implant operation, when the implant operation has failed or a re- operation is needed when a considerable time passes after the implant operation is successfully performed, another implant operation needs to be performed at the position where the pervious implant operation was performed. In this case, an artificial bone replacement material needs to be transplanted for a predetermined period at the position where the previous implant operation was performed.

[8] When the alveolar bone is not sufficient or the re-operation is needed, it is general to perform an implant operation only when the damaged alveolar bone is replaced with an artificial replacement so that the alveolar bone is in a state suitable for the implant operation. In this case, since the time for recovering the damaged bone tissue is added to the total implant operation time, a rescue operation is difficult and a patient is inconvenienced by the increased operation time.

[9] To remove the inconvenience occurring in the step of recovering the damaged alveolar bone, a large implant having a fixture having a cross-sectional diameter of 6 mm or more is used. When a large implant is used, unless the bone tissue is severely damaged, an implant operation can be immediately performed without transplanting the artificial bone replacement material. The implant having a fixture with a relatively large diameter which reduces the time needed for the recovery of the damaged alveolar bone is referred to as a dental rescue implant.

[10] However, the dental rescue implant has a problem in that a fixture of the dental rescue implant is difficult to be transplanted in an alveolar bone because the diameter of the fixture increases compared to the general implant. This is because, as the diameter of the fixture increases, a resisting force due to the friction in the alveolar bone where the fixture of the dental rescue implant is transplanted increases. Thus, a strong rotational force to overcome the increased resisting force is needed. Also, the fixture of the dental rescue implant must bear a strong stress concentration at a particular portion, that is, a portion coupled to a handpiece connecter that transfers a rotational force.

[11] The implant is divided into an external connection type implant and an internal connection type implant according to the connection type between the fixture and the abutment. In the external connection type implant, a connection protrusion having a hexagonal shape is formed on the upper surface of the fixture and a connection hole for the connection of the connection protrusion of the fixture is formed in the lower surface of the abutment so that the connection protrusion of the fixture is inserted in the connection hole for connection. [12] In the internal connection type implant, an inner connection hole is indented from the upper surface in the upper end portion of a fixture and the lower end portion of an abutment is formed to be inserted in the inner connection hole so that the lower end portion of the abutment is inserted in the inner connection hole of the fixture.

[13] In comparison with the inner connection type implant and the external connection type implant, since the inner connection type implant has a contact area between the fixture and a handpiece connector or a contact area between the fixture and the abutment larger than that of the external connection type implant, the screw connection therebetween is less loosen so that the fixture and the handpiece connector or the fixture and the abutment can be stably coupled to each other.

[14] However, the external connection type implant is also widely adopted for its own merits. That is, when the dental rescue implant is of an external connection type, the connection protrusion having a hexagonal shape formed on the fixture and the connection hole having a hexagonal shape provided in the handpiece connector do not bear a strong rotational force so that the handpiece connector spins unengaged or the connection protrusion of the fixture can be damaged.

[15] Thus, based on the differences between the inner connection type implant and the external connection type implant, a dental rescue implant can be formed of the internal connection type implant. However, since the dental rescue implant needs a quite greater rotational force during transplantation than a common implant, it is not sufficient to simply adopt the internal connection type implant. There is a limit in restricting the damage of the fixture that may be generated in the transfer of the rotational force during the fixture transplantation step. Thus, a dental rescue implant having a structure which can bear a strong rotational force applied to the fixture so that a stable rescue implant operation is possible is needed. Disclosure of Invention Technical Problem

[16] To solve the above and/or other problems, the present invention provides an internal fixture for a dental rescue implant which smoothly transfers a relatively large amount of a rotational force needed for an operation of a dental rescue implant having a relatively large diameter so that a rescue operation can be stably performed, the damage in a portion coupled to a handpiece connector during transplantation can be reduced, and a relative rotation of an abutment can be reduced when the fixture is coupled to the abutment.

Advantageous Effects

[17] According to the present invention, since a relatively large rotational force needed when a dental rescue implant having a relatively large diameter is transplanted can be smoothly transferred, a rescue operation can be stably performed. Also, during the transplantation, a damage in the portion where the fixture is coupled to the handpiece connector can be reduced. Furthermore, when the fixture is coupled to the abutment, the relative rotation of the abutment can be reduced. Brief Description of the Drawings

[18] FIG. 1 illustrates a state in which an internal fixture for a dental rescue implant according to an embodiment of the present invention is transplanted;

[19] FIG. 2 is a front side view of an internal fixture for a dental rescue implant according to an embodiment of the present invention;

[20] FIG. 3 is a cross-sectional view of the internal fixture for a dental rescue implant of

FIG. 2;

[21] FIG. 4 is a plan view of the internal fixture for a dental rescue implant of FIG. 2;

[22] FIG. 5 is an enlarged cross-sectional view of a portion A of the internal fixture for a dental rescue implant of FIG. 2;

[23] FIG. 6 is an enlarged cross-sectional view of a portion B of the internal fixture for a dental rescue implant of FIG. 2;

[24] FIG. 7 is a front side view of a handpiece connector used for transplanting the fixture of FIG. 2;

[25] FIG. 8 is a bottom view of the portion B of the internal fixture for a dental rescue implant of FIG. 2;

[26] FIG. 9 is a front side view of an abutment coupled to the fixture of FIG. 2;

[27] FIG. 10 is a bottom view of the abutment of FIG. 9; and

[28] FIG. 11 is a assembly cross-sectional view for explaining a state in which the fixture of FIG. 2 and the abutment of FIG. 9 are coupled to each other by an abutment screw.

Best Mode for Carrying Out the Invention

[29] According to an aspect of the present invention, an internal fixture for a dental rescue implant comprises a main body portion having the diameter of a cross-section of 6 mm to 8 mm relatively larger than the diameter of a cross-section of 5 mm and less of a body portion of a common implant to be directly transplanted in a damaged alveolar bone without a supplement of a bone replacement material, and an inner connection hole formed in an upper end portion of the body portion to be indented to a predetermined depth from an upper surface of the body portion in which a lower end portion of an abutment is inserted to contact each other, and a screw thread formed on an outer surface of the body portion to transplant the body portion in the alveolar bone, wherein at least one connection reinforcing groove is formed on an inner circumferential wall forming the inner connection hole to be indented to a predetermined depth from a surface of the inner circumferential wall and coupled to a connection reinforcing protrusion provided on an outer surface of any of a handpiece connector and the abutment.

[30] The connection reinforcing groove is provided in a plural number to be separated from one another in a lower end portion of the inner circumferential wall.

[31] The number of the connection reinforcing groove is three and separated from one another at an identical interval in a triangular structure.

[32] A guide path connected to the connection reinforcing groove is formed on the inner circumferential wall to guide the connection reinforcing protrusion toward the connection reinforcing groove when the connection reinforcing protrusion formed on the outer surface of any of the handpiece connector and the abutment is coupled to the connection reinforcing groove.

[33] The cross-section of each connection reinforcing groove is substantially semicircular.

[34] The inner circumferential wall of the body portion is inclined such that the cross- section of the inner connection hole gradually decreases from the upper end portion toward the lower end portion of the body portion.

[35] The outer diameter of a screw thread formed in a predetermined height section in the upper end portion of the body portion is larger than the outer diameter of a screw thread in a lower end portion adjacent to the screw thread in the upper end portion of the body portion.

[36] A bevel portion inclined such that the outer diameter of the body portion decreases toward the upper end of the body portion is formed at an edge portion of the upper end portion of the body portion.

[37] The screw thread includes a narrow width vertical section formed parallel to a lengthwise direction of the body portion and having a relatively narrow width, a lower inclined section extending from a lower end of the narrow width vertical section to be inclined with respect to the outer surface of the body portion, and an upper inclined section extending from an upper end of the narrow width vertical section to be inclined with respect to the outer surface of the body portion and having an inclination degree larger than that of the lower inclined section.

[38] The lower inclined section has an inclination degree of 5°to 20°with respect to a radial direction of the body portion.

[39] The upper inclined section has an inclination degree of 30°to 45°with respect to a radial direction of the body portion.

[40] A pitch of the screw thread is 0.6 to 1.25 pitches.

Mode for the Invention [41] The attached drawings for illustrating preferred embodiments of the present invention are referred to in order to gain a sufficient understanding of the present invention, the merits thereof, and the objectives accomplished by the implementation of the present invention.

[42] Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the invention with reference to the attached drawings. Like reference numerals in the drawings denote like elements.

[43] FIG. 1 illustrates a state in which an internal fixture for a dental rescue implant according to an embodiment of the present invention is transplanted. FIG. 2 is a front side view of an internal fixture for a dental rescue implant according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the internal fixture for a dental rescue implant of FIG. 2. FIG. 4 is a plan view of the internal fixture for a dental rescue implant of FIG. 2. FIG. 5 is an enlarged cross-sectional view of a portion A of the internal fixture for a dental rescue implant of FIG. 2. FIG. 6 is an enlarged cross- sectional view of a portion B of the internal fixture for a dental rescue implant of FIG. 2. FIG. 7 is a front side view of a handpiece connector used for transplanting the fixture of FIG. 2. FIG. 8 is a bottom view of the portion B of the internal fixture for a dental rescue implant of FIG. 2. FIG. 9 is a front side view of an abutment coupled to the fixture of FIG. 2. FIG. 10 is a bottom view of the abutment of FIG. 9. FIG. 11 is a assembly cross-sectional view for explaining a state in which the fixture of FIG. 2 and the abutment of FIG. 9 are coupled to each other by an abutment screw.

[44] A dental rescue implant according to the present embodiment is an internal connection type implant includes a fixture 10 transplanted as an artificial tooth root, an abutment 60 coupled to the fixture 10, an abutment screw 70 fixing the abutment 60 to the fixture 10, and an artificial tooth (not shown) coupled to the abutment 60.

[45] As shown in FIG. 1, a large number of teeth 2 are arranged on a gum 1. Normally, there are twenty-eight teeth which cut food into small pieces as a first digestive unit although the number of the teeth 2 may vary according to persons. When any of the teeth 2 is lost (when a posterior portion is lost or damaged), the lost tooth degrades an aesthetic sense and considerably inconveniences biting of food. Accordingly, the fixture 10 is transplanted as a means for replacing a tooth root 2a of the teeth 2 in the gum 1 of a lost tooth. The fixture 10 is manufactured of titanium that has no rejection to a human body.

[46] As shown in FIGS. 2 through 4, the internal fixture 10 for a dental rescue implant according to the present embodiment includes a body portion 20 and a screw thread 30 formed on the outer surface of the body portion 20. An inner connection hole 40 contacting and coupling to a lower end portion of the abutment 60 is indented from the upper surface of the body portion 20 to a predetermined depth. A screw groove 45 screw coupled to the abutment screw 70 is formed in the lower portion of the body portion 20 adjacent to the inner connection hole 40.

[47] The cross-sectional diameter of the fixture 10 denotes the diameter or outer diameter including the screw thread 30 formed on the outer surface of the body portion 20. The cross-sectional diameter D of the fixture 10 of the present embodiment is 6-8 mm that is relatively greater than the cross-sectional diameter of a common fixture that is 5 mm and less. In the present embodiment, the cross-sectional diameter of the fixture 10 is 7 mm.

[48] When a fixture has a cross-sectional diameter that is greater than the cross-section diameter of a common fixture as in the fixture 10 of the present embodiment, the fixture can be directly transplanted in an alveolar bone by a one-time operation without a supplement of a bone replacement material needed for the insufficient alveolar bone or re-operation. Thus, a rescue operation is achieved.

[49] A bevel portion 21 is formed at an edge portion of the upper end portion of the body portion 20 and inclined such that the outer diameter of the body portion 20 decreases toward the upper end of the body portion 20. The bevel portion 21 is to prevent the interference with the coupling between the fixture 10 and the abutment 60 due to the overgrowth of the alveolar bone. When the osseointegration is complete, the bevel portion 21 prevents the fixture 10 from moving upward so as to double the stability of fixing.

[50] In detail, when the fixture 10 is transplanted, when the fixture 10 is transplanted, the alveolar bone grows and the abutment 60 and the artificial tooth are coupled after a predetermined time for the osseointegration passes. In some cases, during the osseointegration, the alveolar bone overgrows to partially block the opening of the inner connection hole 40 of the fixture 10 so as to interfere with the coupling between the fixture 10 and the abutment 60. However, when the bevel portion 21 is provided as in the present embodiment, a predetermined space is obtained between the alveolar bone and the opening of the inner connection hole 40 from the screw thread 30 in the upper end of the body portion 20. Thus, even when the alveolar bone overgrows, the possibility to interfere with the coupling between the fixture 10 and the abutment 60 is low. When the osseointegration is complete, the alveolar bone grows over the inclined surface of the bevel portion 21 so that the upward movement of the fixture 10 that is transplanted is prevented. Thus, the fixture 10 is stably fixed in the alveolar bone.

[51] A taper portion 23 is formed at an edge portion of the lower end portion of the body portion 20 and inclined such that the outer diameter of the body portion 20 decreases toward the lower end of the body portion 20. The taper portion 23 facilitates the initial entry of the fixture 10 in a hole formed in the alveolar bone using a tool such as a drill so that the transplantation is made easy. [52] A plurality of cutting edge portions 25 are formed in the circumferential direction of the body portion 20 in the lower portion of the body portion 20. The cutting edge portions 25 are formed at identical intervals and have sharp tip ends. In the present embodiment, there are four cutting edge portions 25, but the number of the cutting edge portions 25 can be appropriately changed.

[53] The screw thread 30 is formed on the outer surface of the body portion 20. As shown in FIG. 5, the outer diameter of a screw thread 30a formed in the upper end portion of the body portion 20 is greater than that of a screw thread 30b in the lower end portion adjacent thereto so that a step d is formed. Due to this structure, the initial stability in a compact bone can be improved.

[54] In detail, the fixture 10 that moves downward in the transplantation step is screw coupled to the alveolar bone while forming a female screw thread in the alveolar bone. However, when the outer diameter of the screw thread 30 formed on the body portion 20 is the same as a whole, the female screw thread formed in the upper portion of the alveolar bone can be slightly loosen as the screw thread 30b formed in the lower portion of the body portion 20 of the fixture 10 passes thereon.

[55] Thus, if the female screw thread in the compact bone where the screw thread 30a in the upper end portion of the body portion 20 is located is larger than the screw thread 30a in the upper end portion of the body portion 20 of the fixture 10, an allowance space where the fixture 10 can move slightly before the osseointegration between the fixture 10 and the alveolar bone is performed, so that the initial fixing of the fixture 10 has no accuracy. In the present embodiment, as the diameter of the screw thread 30a in the upper end portion of the body portion 20 is larger than that of the screw thread 30b in the lower portion adjacent thereto, the female screw thread is formed again in the compact bone as the screw thread 30a in the upper end portion of the body portion 20 enters in the compact bone of the alveolar bone. Accordingly, after transplantation is complete, the fixture 10 is closely coupled to the compact bone so that the initial fixing can be improved.

[56] As shown in FIG. 6, the screw thread 30 includes a narrow width vertical section 32 having a relatively narrow width and parallel to the lengthwise direction of the body portion 20, a lower inclined section 34 extending from the lower end of the narrow width vertical section 32 and inclined to the outer surface of the body portion 20, and an upper inclined section 36 extending from the upper end of the narrow width vertical section 32, inclined to the outer surface of the body portion 20, and having a greater inclination degree than that of the lower inclined section 34. Since the width of the narrow width vertical section 32 is small, the edge of the screw thread 30 becomes sharp so that the transplantation is made easy.

[57] The lower inclined section 34 is to compensate for a pressing force according to the lengthwise direction of the body portion 20 and has an inclination degree θ between 5° -20° with respect to the outer surface of the body portion 20. The lower inclined section 34 is a portion using the merit of a rectangular screw. In contrast, the upper inclined section 36 is to secure a combining force for the smooth transplantation of the body portion 20 and simultaneously for the prevention of easy escape and has an inclination degree θ between 30°-45°with respect to the outer surface of the body portion 20. The upper inclined section 36 is a portion using the merit of a V-screw.

[58] In view of the above structure, the screw thread 30 according to the present embodiment takes only the merits of the V-screw and the rectangular screw. Upper and lower rounding portions (not shown) are respectively formed at areas where the upper and lower inclined sections 34 and 36 contact the outer surface of the body portion 20. In the present embodiment, the upper and lower rounding portions have the same radius of curvature, but the right scope of the present invention is not limited thereto.

[59] When the fixture 10 is operated after the screw thread 30 is formed on the outer surface of the body portion 20, stress is hardly generated in a bone and further stress and strain are not locally concentrated at the lower end portion of the screw contacting the alveolar bone and the base portion of the fixture 10. Thus, bone loss due to a long- term bite force is not generated.

[60] Also, in the screw thread 30 of the present embodiment, a relatively large shear force is formed by the structural characteristic. A load applied when the fixture 10 is vertically transplanted increases stress around the fixture 10 as the inclination at which the load is applied increases. In particular, stress may increase in a weak tooth adjustment portion, but a load is applied in the lengthwise direction of the fixture 10 so that stress of a tooth adjustment decreases. In addition, the stress in the area of the abutment 60 decreases so that the danger of breakage is reduced. Since the inclination θ of the upper inclined section 36 in the screw thread 30 is relatively greater than the inclination θ of the lower inclined section 34, the amount of the load that the boundary surface of the alveolar bone supports decreases.

[61] The pitch P of the screw thread 30 may be one of 0.6 through 1.25 pitches. When a

0.8 pitch is adopted as in the present embodiment, the screw thread 30 of the fixture 10 is relatively dense with respect to the dental rescue implant so that the number of contacts with the alveolar bone may increase.

[62] As shown in FIGS. 1, 3, and 4, the inner connection hole 40 in which the lower end portion is inserted is indented in the upper end portion of the body portion 20 to a predetermined depth. Since the dental rescue implant according to the present embodiment is of an internal connection type, a handpiece connector 50 is inserted in the inner connection hole 40 of the fixture 10 and then a rotational force generated by a motorized tool for an implant operation is transferred to the fixture 10 via the handpiece connector 50.

[63] The handpiece connector 50 will be first described prior to a connection reinforcing groove 41 formed in the inner connection hole 40. As shown in FIGS. 7 and 8, the handpiece connector 50 includes a handpiece body portion 51, a handpiece connection portion 53, and a rotational force transfer portion 55 having a connection reinforcing protrusion 57.

[64] The handpiece connection portion 53 formed in the upper portion of the handpiece body portion 51 is capable of coupling to a handpiece (not shown). The rotational force transfer portion 55 is inserted in the inner connection hole 40 of the fixture 10. When the rotational force transfer portion 55 is inserted in the inner connection hole 40 of the fixture 10 and closely contacts an inner circumferential wall, the connection reinforcing protrusion 57 is forcibly coupled to the connection reinforcing groove 41 of the fixture 10 that is described later.

[65] Referring back to FIGS. 1, 3, and 4, the connection reinforcing groove 41 is indented to a predetermined depth from the inner circumferential wall of the inner connection hole 40 of the fixture 10. A guide path 43 (please refer to FIG. 1) is formed above the connection reinforcing groove 41, through which the connection reinforcing protrusion 57 of the handpiece connector 50 is guided toward the connection reinforcing groove 41 when the connection reinforcing protrusion 57 is coupled to the connection reinforcing groove 41. Accordingly, when the handpiece connector 50 is coupled to the inner connection hole 40, the connection reinforcing protrusion 57 formed on the handpiece connector 50 is guided to be forcibly coupled to the connection reinforcing groove 41.

[66] In the present embodiment, there are three connection reinforcing grooves 41 arranged to be separated from one another at the identical interval in a triangular structure. Since the diameter of the fixture 10 is large in the dental rescue implant, a strong rotational force of the handpiece connector 50 is generated transferred and the resistance against the alveolar bone is relatively great. Nevertheless, the forcible coupling between the connection reinforcing groove 41 and the connection reinforcing protrusion 57 produces a greater coupling force. In particular, when the connection reinforcing groove 41 is arranged in the triangular structure, the connection reinforcing groove 41 and the connection reinforcing protrusion 57 can be more stably connected so that a greater rotational force can be transferred to the fixture 10. Also, since the connection reinforcing groove 41 can be formed in the inner circumferential wall in the triangular structure through a cutting process, the process is easier than a case of a hexagonal structure that requires a discharge process due to the difficulty in the cutting process.

[67] Consequently, when the connection reinforcing groove 41 is provided in the inner connection hole 40 of the dental rescue implant and the connection reinforcing protrusion 57 is provided in the handpiece connector 50 so that the connection reinforcing groove 41 and the connection reinforcing protrusion 57 are coupled to each other, the connection therebetween becomes stronger so that the implant operation can be stably performed in spite of the great rotational force needed for the transplantation of the fixture 10 in the alveolar bone. If the connection reinforcing groove 41 is not provided in the fixture 10, the great rotational force occurring during the transplantation of the fixture 10 in the alveolar bone may make the handpiece connector 50 spin unengaged or damage the connection protrusion of the fixture so that the transplantation is not performed smoothly. However, in the present embodiment, such a problem can hardly occur

[68] In addition, in the present embodiment, since the inner circumferential wall of the inner connection hole 40 is tapered such that the cross-section thereof gradually decreases from the upper end to the lower end. Thus, a contact area increases when the inner connection hole 40 is coupled to the handpiece connector 50. The increase in the contact area increases the amount of a transferable rotational force so that the present invention can be applied to a case in which a great rotational force is applied. Also, since the amount of stress applied for each unit area of the contact area decreases with respect to the same rotational force, even when a great rotational force is transferred, the possibility of the damage to the fixture 10 can be reduced.

[69] As shown in FIGS. 9 and 10, a connection reinforcing protrusion 61 coupled to the connection reinforcing groove 41 of the fixture 10 is provided on the outer surface of the abutment 60. Thus, when the abutment 60 is coupled to the fixturelO, the forcible connection between the connection reinforcing groove 41 and the connection reinforcing protrusion 61 restricts the rotation of an upper denture.

[70] In the process of an implant operation using an internal fixture for a dental rescue implant according to an embodiment of the present invention, first, as a preliminary work for a transplantation work of the fixture 10, a hole having a diameter less than the diameter of the fixture 10 is formed using a tool such as a drill at a position on an alveolar bone where the fixture 10 is to be transplanted.

[71] Next, the handpiece connector 50 and the fixture 10 are coupled to each other. That is, the lower end portion of the handpiece connector 50 is coupled to the inner connection hole 40. The connection reinforcing protrusion 57 formed on the handpiece connector 50 is guided along the guide path 43 and thus forcibly connected to the connection reinforcing groove 41.

[72] The rotational force needed for the transplantation of the fixture 10 is generally provided by a motorized tool (not shown) for an implant operation that consists of a handpiece and a driving apparatus including a compact motor. Thus, when the fixture 10 is transplanted in the alveolar bone by operating the motorized tool for an implant operation, since the screw thread 30 is formed on the outer surface of the fixture 10, the fixture 10 is transplanted by moving downward as a rotation force is applied in a state where the lower surface of the fixture 10 contacts the upper surface of the hole in the alveolar bone provided in advance.

[73] Since the diameter of the fixture 10 is generally larger than that of the fixture 10, a large amount of resistance is generated. Thus, when a relatively greater rotational force is applied, since the inner circumferential wall forming the inner connection hole 40 is tapered and the connection reinforcing groove 41 of the inner circumferential wall is coupled to the connection reinforcing protrusion 57 of the handpiece connector 50, a coupling strength increases so that the phenomenon that the handpiece connector 50 spins unengaged or the inner circumferential wall of the fixture 10 is damaged hardly occurs.

[74] Also, since the outer diameter of the screw thread 30a formed in the upper end portion of the body portion 20 is larger than that of the screw thread 30b in the lower end portion thereof that is adjacent to the screw thread 30a, the initial fixing in the alveolar bone after the transplantation can be improved.

[75] After the fixture 10 is transplanted, another operation is performed again after several weeks pass for the initial fixing so that the alveolar bone grows so that the fixture 10 and the alveolar bone are osseointegrated. During the osseointegration, the alveolar bone sometimes over-grows to interfere with the coupling with the abutment 60, but the interference is prevented by the bevel portion 21.

[76] In the implant operation performed after the initial fixing is complete, as shown in

FIG. 11, as the connection reinforcing protrusion 17 formed on the abutment 60 is forcibly coupled to the connection reinforcing groove 41 of the fixture 10 transplanted in the alveolar bone, the abutment 60 is coupled to the fixture 10. The abutment 60 is fixed to the fixture 10 by the abutment screw 70. When the abutment 60 is fixed to the fixture 10, an artificial tooth (not shown) is coupled to the upper portion of the abutment 60 so that the operation of the internal connection type implant 10 is complete.

[77] In the above-described embodiment, although the cross-section of the connection reinforcing groove is described to have a semi-circular shape, a shape such as a crescent moon smaller than a semi-circle can be adopted.

[78] While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Industrial Applicability

[79] According to the present invention, since a relatively large rotational force needed when a dental rescue implant having a relatively large diameter is transplanted can be smoothly transferred, a rescue operation can be stably performed. Also, during the transplantation, a damage in the portion where the fixture is coupled to the handpiece connector can be reduced. Furthermore, when the fixture is coupled to the abutment, the relative rotation of the abutment can be reduced.

Claims

[1] An internal fixture for a dental rescue implant comprising: a main body portion having the diameter of a cross-section of 6 mm to 8 mm relatively larger than the diameter of a cross-section of 5 mm and less of a body portion of a common implant to be directly transplanted in a damaged alveolar bone without a supplement of a bone replacement material, and an inner connection hole formed in an upper end portion of the body portion to be indented to a predetermined depth from an upper surface of the body portion in which a lower end portion of an abutment is inserted to contact each other, and a screw thread formed on an outer surface of the body portion to transplant the body portion in the alveolar bone, wherein at least one connection reinforcing groove is formed on an inner circumferential wall forming the inner connection hole to be indented to a predetermined depth from a surface of the inner circumferential wall and coupled to a connection reinforcing protrusion provided on an outer surface of any of a handpiece connector and the abutment.

[2] The internal fixture for a dental rescue implant of claim 1, wherein the connection reinforcing groove is provided in a plural number to be separated from one another in a lower end portion of the inner circumferential wall.

[3] The internal fixture for a dental rescue implant of claim 2, wherein the number of the connection reinforcing groove is three and separated from one another at an identical interval in a triangular structure.

[4] The internal fixture for a dental rescue implant of claim 2, wherein a guide path connected to the connection reinforcing groove is formed on the inner circumferential wall to guide the connection reinforcing protrusion toward the connection reinforcing groove when the connection reinforcing protrusion formed on the outer surface of any of the handpiece connector and the abutment is coupled to the connection reinforcing groove.

[5] The internal fixture for a dental rescue implant of claim 4, wherein the cross- section of each connection reinforcing groove is substantially semi-circular.

[6] The internal fixture for a dental rescue implant of claim 1, wherein the inner circumferential wall of the body portion is inclined such that the cross-section of the inner connection hole gradually decreases from the upper end portion toward the lower end portion of the body portion.

[7] The internal fixture for a dental rescue implant of claim 1, wherein the outer diameter of a screw thread formed in a predetermined height section in the upper end portion of the body portion is larger than the outer diameter of a screw thread in a lower end portion adjacent to the screw thread in the upper end portion of the body portion. [8] The internal fixture for a dental rescue implant of claim 1, wherein a bevel portion inclined such that the outer diameter of the body portion decreases toward the upper end of the body portion is formed at an edge portion of the upper end portion of the body portion. [9] The internal fixture for a dental rescue implant of claim 1, wherein the screw thread includes: a narrow width vertical section formed parallel to a lengthwise direction of the body portion and having a relatively narrow width; a lower inclined section extending from a lower end of the narrow width vertical section to be inclined with respect to the outer surface of the body portion; and an upper inclined section extending from an upper end of the narrow width vertical section to be inclined with respect to the outer surface of the body portion and having an inclination degree larger than that of the lower inclined sec tion. [10] The internal fixture for a dental rescue implant of claim 9, wherein the lower inclined section has an inclination degree of 5°to 20°with respect to a radial direction of the body portion. [11] The internal fixture for a dental rescue implant of claim 9, wherein the upper inclined section has an inclination degree of 30°to 45°with respect to a radial direction of the body portion. [12] The internal fixture for a dental rescue implant of claim 1, wherein a pitch of the screw thread is 0.6 to 1.25 pitches.