WO2003055403A1

WO2003055403A1 - Expandable dental implant

Info

Publication number: WO2003055403A1
Application number: PCT/KR2002/002360
Authority: WO
Inventors: Jong-Jin Kwon
Original assignee: Jong-Jin Kwon
Priority date: 2001-12-29
Filing date: 2002-12-14
Publication date: 2003-07-10
Also published as: KR20030059372A; AU2002367158A1

Abstract

An expandable dental implant is primarily and steadily fixed in an alveolar bone just with a simple structure, in which a lower portion of a body of the dental implant having slits is pressed and widened outward by a rotary shaft moving downward through screw fastening with the body, without using a separate intermediate, so that a patient can chew food in a short period of time after dental implantation.

Description

EXPANDABLE DENTAL IMPLANT

Technical Field

The present invention relates to a dental implant, and more particularly, to an expandable dental implant which has a simple structure, thereby reducing a manufacturing cost and rarely has a gap with an alveolar bone after being fixed in the alveolar bone.

Artificial teeth are man-made teeth having almost the same appearance and functions as human natural teeth and are used to replace natural teeth lost due to various causes.

Prosthetic appliances, dentures, and artificial teeth are used as substitutes for natural teeth. When using prosthetic appliances, since other neighboring natural teeth need to be partially ground, the natural teeth are damaged a lot. Moreover, the life span of prosthetic appliances is about 10 years - not long term. When using dentures, natural teeth are damaged during preparation for fabricating dentures. In addition, dentures may come out of a mouth and make users uncomfortably feel a foreign body sensation in their mouths. For these problems, the use rates of prosthetic appliances and dentures haven been decreased. In the meantime, when artificial teeth are fixed to an alveolar bone, other neighboring natural teeth are not damaged. Artificial teeth after being fixed are sufficiently the same as natural teeth in appearance and functions to be difficult to be discriminated from natural teeth. In addition, their life span is semi permanent depending on maintenance. Accordingly, in spite of relatively expensive charges, artificial teeth have been widely used.

When an artificial tooth is fixed to an alveolar bone, a dental implant is used. In other words, the body of a dental implant is fixed in an alveolar bone, and then an artificial tooth is joined with the body of the dental implant so that the artificial tooth is used like a natural tooth. Background Art

A conventional dental implant will be described in detail with reference FIGS. 1 through 4B. The conventional dental implant was developed by Sargon in the United States and is chiefly made of titanium which is strong and harmless to a human body. The dental implant includes a body 1 having a predetermined length. The body 1 is a pipe type having an internal bore. An external screw thread 2 is formed on the exterior surface of the body 1 in order to securely fix the body 1 in an alveolar bone. A protuberance 3 is formed along the internal circumference roughly in the middle of the internal bore of the body 1. An internal screw thread 4 is formed on the interior surface of the body 1 above the protuberance 3 in order to fix an artificial tooth to the body 1. A plurality of slits 5 are formed in the lengthwise direction of the body 1 below the protuberance 3. A slanting side 6 is formed on the interior surface of the body 1 in the portion where the slits 5 are formed so that the internal bore of the body 1 is wider toward the bottom end of the body 1. A moving element 7 is provided within the internal bore of the body 1 below the protuberance 3. The moving element 7 has an appearance tapered upward, and its maximum external diameter is almost the same as the internal diameter "a" of the body 1 at the bottom end of the slanting side 6. A mail screw 8 is inserted into the internal bore of the body 1 from the above. A head 9 is integrated with the top end of the mail screw 8 so that the head 9 is caught on the protuberance 3 and thus prevents the mail screw 8 from slipping down off the body 1. A threaded hole 10 is formed to vertically pierce through the center of the moving element 7 so that the moving element 7 is screw fastened to the mail screw 8 with the rotation of the mail screw 8.

The following description concerns a method of fixing an artificial tooth to an alveolar bone using the above-described dental implant. In order to fix an artificial tooth to an alveolar bone, a gum is cut by a necessary length and opened a little. Next, the alveolar bone is drilled using a medical drill to form a hole, as shown in FIG. 4A.

Next, the dental implant is inserted into the hole formed in the alveolar bone. In this state, the lower portion of the body 1 of the dental implant where the slits 5 are formed is forcedly widened outward so that the body 1 is primarily fixed in the alveolar bone.

As time lapses after the body 1 is fixed in the alveolar bone, osteoblasts adhere to the body 1 , and synostosis occurs, so the hole formed in the alveolar bone is filled up. In a predetermined period of time after the body 1 is primarily fixed in the alveolar bone, a gap between the alveolar bone and the body 1 of the dental implant is filled up so that the body 1 is secondarily and securely fixed in the alveolar bone. After the double fixation of the dental implant is completed, an artificial tooth is joined with the dental implant. Then, the artificial tooth is steady enough not to be moved by a normal force to a natural tooth (for example, a force applied to a tooth when a person chews food). In the meantime, the external screw thread 2 formed on the exterior surface of the body 1 enhances the secondary fixation of the body 1 in the alveolar bone when the gap between the alveolar bone and the body 1 is filled up due to the synostosis.

After the body 1 of the dental implant is secondarily fixed in the alveolar bone, a prosthesis for fixing the artificial tooth is screw fastened to the body 1 through the internal screw thread 4 formed on the interior surface of the body 1 above the protuberance 3. The artificial tooth is fixed on the gum by the support of the prosthesis. If the artificial tooth is fixed to the alveolar bone using the above-described method, as shown in FIG. 4B, the artificial tooth serves to chew food with almost the same appearance as a natural tooth. In the above-described method, the procedure in which the lower portion of the body 1 having the slits 5 is forcedly widened outward in order to primarily fix the body 1 in the alveolar bone will be described in detail with reference to FIGS. 2A and 2B.

FIG. 2A shows a state of the conventional dental implant before the lower portion of the body 1 is widened outward. Referring to FIG. 2A, the mail screw 8 is inserted in to the internal bore of the body 1 from the above and is suspended from the protuberance 3 because the head 9 is caught on the protuberance 3. In the lower portion of the body 1 where the slanting side 6 is formed on the interior surface, the upward tapered moving element 7 is screw coupled with the lower end portion of the mail screw 8.

In the state shown in FIG. 2A, a tool for rotating the mail screw 8 is inserted into the internal bore of the body 1 from the above. When the tool is rotated in one direction (fastening direction) so that the mail screw 8 is rotated in one direction, the mail screw 8 just rotates without moving downward since the head 9 at the top of the mail screw 8 is caught on the protuberance 3 formed on the body 1. During the rotation of the mail screw 8, the moving element 7 screw coupled with the lower end portion of the mail screw 8 through the threaded hole 10 moves upward.

It will be understood that a pit with which the end of the tool mates is formed in the head 9 at the top of the mail screw 8 in order to rotate the mail screw 8 in one direction using the tool.

On the interior surface of the lower portion of the body 1 having the slits 5, the slanting side 6 is formed so that the internal bore of the body 1 is gradually narrowed from the bottom toward the protuberance 3. As described above, the moving element 7 is tapered upward, and its maximum external diameter is the same as or slightly smaller than the internal diameter "a" of the body 1 at the bottom end of the slanting side 6. Accordingly, as the moving element 7 moves upward, the lower portion of the body 1 having the slits 5 is pressed out by the moving element 7 so that the lower portion of the body 1 is widened out, as shown in FIG. 2B. Consequently, the body 1 is primarily fixed in the alveolar bone with a strong contact force.

As described above, in order to primarily fix the body 1 of the conventional dental implant in an alveolar bone by widening outward the portion of the body 1 having the slits 5, the moving element 7 is provided as an intermediate between the mail screw 8 and the interior surface of the body 1. Such structure has the following problems.

Firstly, since the moving element 7 is used as an intermediate in order to wide outward the portion of the body 1 having the slits 5 while moving upward due to the rotation of the mail screw 8, instead of making the mail screw 8 directly press outward the portion of the body 1 having the slits 5, the structure of the conventional dental implant is complex, thereby increasing a manufacturing cost. Consequently, patients are required to pay an expensive medical fee. Secondly, since the entire dimensions (external diameter and height) of the body 1 are restricted, the portion of the body 1 having the slits 5 is relatively thinner than the other portion of the body 1. Accordingly, during the primary fixation of the body 1 and the synostosis, the body 1 cannot steadily serve as a support, and thus even a slight impact may cause the body 1 to be loose. As a result, the success rate of dental implantation is decreased. In addition, even if an artificial tooth is successfully fixed, a patient needs to wait a long period of time until he/she can chew food. In other words, however accurately drilling is performed, there is a gap greater than 200 microns between the surface of the conventional dental implant and an alveolar bone. It takes at least three months for the gap is filled with osteoblasts.

Thirdly, since the portion of the body 1 having the slits 5 is thin and thus has a wide internal bore. Accordingly, after the body 1 is primarily fixed in an alveolar bone, there exists a wide space in the lower portion of the body 1 (see FIG. 2B). As a result, it takes a long period of time until an artificial tooth is completely fixed by filling up the space in the lower portion of the body 1 of the conventional dental implant through synostosis. In some cases, the space within the lower portion of the body 1 is not filled with osteoblasts but with epithelial cells (soft tissue), so a patient needs to be operated on again.

Disclosure of the Invention

The present invention provides an expandable dental implant which is primarily and steadily fixed in an alveolar bone just with a simple structure in which a lower portion of a body having slits is pressed and widened outward by a rotary shaft moving downward through screw fastening with the body, without using a separate intermediate, so that the period of medical care is reduced, and thus a patient can chew food in a short period of time after dental implantation.

The present invention also provides an expandable dental implant which has a small space in a lower portion of a body in a state where the body is primarily fixed in an alveolar bone so that the body is secondarily fixed in the alveolar bone through synostosis between the body and an alveolar bone within a short period of time.

According to an aspect of the present invention, there is provided a dental implant including a body and a rotary shaft. The body is a cylindrical pipe type having an internal bore and a predetermined length. The body includes an internal screw thread, which is formed on the interior surface of an upper portion of the body on the basis of a predetermined portion of the body, and a plurality of slits, which are formed in the lengthwise direction of the body in a lower portion of the body on the basis of the predetermined portion. The rotary shaft is a cylindrical structure having an external diameter a little smaller than the internal diameter of the body. The rotary shaft is vertically inserted in the internal bore of the body and includes a screw thread formed on the exterior surface of a top end portion of the rotary shaft to be engaged with the internal screw thread of the body so that the rotary shaft is fastened to or loosened from the body due to its rotation. A slanting side is formed on the interior surface of the lower portion of the body, in which the slits are formed, such that the internal diameter of the body is gradually decreased toward the bottom thereof. The rotary shaft rotating in a fastening direction moves downward, becomes to be in contact with the slanting side, and presses and widens the lower portion of the body having the slits outward.

An external screw thread is further formed on the exterior surface of the body in order to securely fix the body in an alveolar bone. The body is chiefly made of titanium.

The internal screw thread is formed on the interior surface of the body above the middle portion thereof, and the plurality of slits are formed in a portion of the body below the middle portion thereof in a vertical direction.

Brief Description of the Drawings

FIG. 1 is an exploded perspective view of a conventional dental implant.

FIG. 2A is a vertical cross-section of the conventional dental implant before a lower portion of a body is widened outward.

FIG. 2B is a vertical cross-section of the conventional dental implant in a state where the lower portion of the body is widened outward.

FIG. 3 is an enlarged cross-section of the conventional dental implant shown in FIG. 2B, taken along the line l-l.

FIG. 4A shows a state in which a hole is formed in an alveolar bone in order to implant the body of the conventional dental implant in the alveolar bone.

FIG. 4B shows a state in which the body of the conventional dental implant is inserted and fixed in the hole formed in the alveolar bone. FIG. 5 is an exploded perspective view of a dental implant according to the present invention.

FIG. 6A is a vertical cross-section of the dental implant of the present invention before a lower portion of a body is widened outward. FIG. 6B is a vertical cross-section of the dental implant of the present invention in a state where the lower portion of the body is widened outward.

FIG. 7 is an enlarged cross-section of the dental implant shown in FIG. 6B, taken along the line 11-11. FIG. 8A shows a state in which a hole is formed in an alveolar bone in order to implant the body of the dental implant of the present invention in the alveolar bone.

FIG. 8B shows a state in which the body of the dental implant of the present invention is inserted and fixed in the hole formed in the alveolar bone.

Best mode for carrying out the Invention

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 5 through 8B. Referring to FIGS. 5 through 7, a dental implant according to a preferred embodiment of the present invention is chiefly made of titanium which is strong and harmless to a human body. The dental implant includes a body 11 having a predetermined length. The body 11 is a pipe type having an internal bore. An external screw thread 12 is formed on the exterior surface of the body 11 in order to securely fix the body 11 in an alveolar bone. An internal screw thread 14 is formed on the interior surface of an upper portion of the body 11 on the basis of the middle of the body 11 in order to fix an artificial tooth to the body 11. A plurality of slits 15 are formed in the lengthwise direction of the body 11 in a lower portion of the body 11. A rotary shaft 16 having an external diameter a little smaller than the internal diameter of the body 11 is inserted in the internal bore of the body 11 from the above. A rotary shaft screw thread 17 is formed on the exterior surface of a top end portion of the rotary shaft 16 to be engaged with the internal screw thread 14 of the body 11 so that the rotary shaft 15 is fastened to or loosened from the body 11 due to its rotation. A slanting side 18 is formed on the interior surface of the lower portion of the body 11 , in which the slits 15 are formed, such that the internal diameter of the body 11 is gradually decreased toward the bottom thereof. Accordingly, when the rotary shaft 16 rotates in a fastening direction, the rotary shaft 16 moves downward, becomes to be in contact with the slanting side 18, and presses the lower portion of the body 11 having the slits 15. As a result, the lower portion having the slits 15 is widened outward.

Referring to FIG. 5 through 6B, the external screw thread 12 is formed on the exterior surface of the body 11. However, the present invention is not restricted thereto. It will be easily understood by those skilled in the art that the exterior surface of the body 11 may be simply smooth, or engraved or embossed in various patterns

Referring to FIG. 7, four slits 15 are formed in the body 11. However, the present invention is not restricted thereto. It will be easily understood by those skilled in the art that two through six slits may be formed.

The following description concerns a method of fixing an artificial tooth to an alveolar bone using a dental implant having the above described structure according to the present invention. In order to fix an artificial tooth to an alveolar bone, as described in the background art, a gum is cut by a necessary length and opened a little. Next, the alveolar bone is drilled using a medical drill to form a hole, as shown in FIG. 8A.

Next, the dental implant is inserted into the hole formed in the alveolar bone. In this state, the lower portion of the body 11 of the dental implant where the slits 15 are formed is forcedly widened outward so that the body 11 is primarily fixed in the alveolar bone.

As time lapses after the body 11 is fixed in the alveolar bone, osteoblasts adhere to the body 11 , and synostosis occurs, so the hole formed in the alveolar bone is filled up. In a predetermined period of time after the body 11 is primarily fixed in the alveolar bone, a gap between the alveolar bone and the body 11 of the dental implant is filled up so that the body 11 is secondarily and securely fixed in the alveolar bone. After the double fixation of the dental implant of the present invention is completed, an artificial tooth is joined with the dental implant. Then, the artificial tooth is steady enough not to be moved by a normal force to a natural tooth (for example, a force applied to a tooth when a person chews food).

In the meantime, the external screw thread 12 formed on the exterior surface of the body 11 enhances the secondary fixation of the body 11 in the alveolar bone when the gap between the alveolar bone and the body 11 is filled up due to the synostosis.

After the body 11 of the dental implant is secondarily fixed in the alveolar bone, a prosthesis for fixing the artificial tooth is screw fastened to the body 11 through the internal screw thread 14 formed on the interior surface of the upper portion of the body 11. The artificial tooth is fixed on the gum by the support of the prosthesis. If the artificial tooth is fixed to the alveolar bone using the above-described method, as shown in FIG. 8B, the artificial tooth can serve to chew food with almost the same appearance as a natural tooth within a short period of time.

In the above-described method, the procedure in which the lower portion of the body 11 having the slits 15 is forcedly widened outward in order to primarily fix the body 11 in the alveolar bone will be described in detail with reference to FIGS. 6A and 6B. FIG. 6A shows a state of the dental implant of the present invention before the lower portion of the body 11 is widened outward. Referring to FIG. 6A, the rotary shaft 16 is inserted in to the internal bore of the body 11 from the above. Here, the rotary shaft screw thread 17 is engaged with the internal screw thread 14 so that rotary shaft 16 is screw coupled with the body 11. In the state shown in FIG. 6A, a tool for rotating the rotary shaft 16 is inserted into the internal bore of the body 11 from the above. When the tool is rotated in one direction (fastening direction), the rotary shaft screw thread 17 formed at the top end portion of the rotary shaft 16 is engaged with the internal screw thread 14 formed on the interior surface of the body 11 so that the rotary shaft 16 moves downward. It will be easily understood by those skilled in the art that a pit with which the end of the tool mates is formed in the top surface of the rotary shaft 16 in order to rotate the rotary shaft 16 in the fastening direction using the tool.

On the interior surface of the lower portion of the body 11 having the slits 15, the slanting side 18 is formed so that the internal bore of the body 11 is gradually narrowed toward the bottom. In addition, the external diameter of the rotary shaft 16 is a little smaller than the diameter "a'" of the internal bore of the body 11 except for the portion of the body having the slanting side 18. Accordingly, as the rotary shaft 16 moves downward, the lower portion of the body 11 having the slits 15 is pressed out by the rotary shaft 16 so that the lower portion of the body 11 is widened outward, as shown in FIG. 6B. Consequently, the body 11 is primarily fixed in the alveolar bone with a strong contact force. In this state, synostosis occurs, and thus the gap between the body 11 and the alveolar bone is filled up. As a result, the body 11 is secondarily and steadily fixed in the alveolar bone.

In the state in which the lower portion having the slits 15 in the body 11 is widened outward so that the body 11 is primarily fixed in the alveolar bone, the rotary shaft 16 is positioned in the lower portion of the body 11. Accordingly, even if the lower portion of the body 11 is widened outward, an inner space in the lower portion of the body 11 is roughly filled with the rotary shaft 16.

Industrial Applicability In a dental implant for fixing an artificial tooth according to the present invention, the rotary shaft 16 directly applies an outward pressure to the body 11 in order to widen the lower portion of the body 11 having the slits 15 outward so that the body 11 is primarily fixed in the alveolar bone, without using an intermediate. Accordingly, the present invention provides various advantages as follows.

Firstly, since the rotary shaft 16 moving downward directly presses and widens outward the lower portion of the body 11 having the slits 15, the structure of the dental implant is simplified, thereby reducing a manufacturing cost. Consequently, charges for dental implantation that patients must pay are decreased.

Secondly, since a separate intermediate between the rotary shaft 16 and the body 11 is not used, the lower portion of the body 11 having the slits 15 can be made thick within predetermined ranges of the entire dimensions (external diameter and height) of the body 11 , so the body 11 steadily serves as a support during primary fixation and synostosis for secondary fixation thereafter. Accordingly, the fixing force of the body 11 is sufficiently improved for the body 11 not to be shaken due to normal impacts. As a result, the success rate of dental implantation is increased. In addition, a period of time after the successful fixation of an artificial tooth until a patient can chew food is remarkably reduced.

Thirdly, since the lower portion of the body 11 having the slits 15 is thick, the internal diameter of the lower portion of the body 11 is also small. In addition, the internal space of the lower portion of the body 11 is mostly filled with the rotary shaft 16. Since an internal space rarely exists within the lower portion of the body 11 even immediately after the body 11 is primarily fixed in an alveolar bone, it does not take a long period time for the space between the body 11 and the alveolar bone to be filled up due to synostosis. Accordingly, a period of time necessary for completion of fixation of an artificial tooth is shortened. It rarely happens that the space within the lower portion of the body 11 is not filled with osteoblasts but with epithelial cells (soft tissue), so the probability of requiring reoperation is very low.

Claims

What is claimed is:

1. A dental implant comprising: a body, which is a cylindrical pipe type having an internal bore and a predetermined length, the body comprising an internal screw thread, which is formed on the interior surface of an upper portion of the body on the basis of a predetermined portion of the body, and a plurality of slits, which are formed in the lengthwise direction of the body in a lower portion of the body on the basis of the predetermined portion; and a rotary shaft, which is a cylindrical structure having an external diameter a little smaller than the internal diameter of the body, the rotary shaft being vertically inserted in the internal bore of the body and comprising a screw thread formed on the exterior surface of a top end portion of the rotary shaft to be engaged with the internal screw thread of the body so that the rotary shaft is fastened to or loosened from the body due to its rotation, wherein a slanting side is formed on the interior surface of the lower portion of the body, in which the slits are formed, such that the internal diameter of the body is gradually decreased toward the bottom thereof, and the rotary shaft rotating in a fastening direction moves downward, becomes to be in contact with the slanting side, and presses and widens the lower portion of the body having the slits outward.

2. The dental implant of claim 1 , wherein an external screw thread is further formed on the exterior surface of the body in order to securely fix the body in an alveolar bone.

3. The dental implant of claim 1 , wherein the body is chiefly made of titanium.

4. The dental implant of claim 1 , wherein the internal screw thread is formed on the interior surface of the body above the middle portion thereof, and the plurality of slits are formed in a portion of the body below the middle portion thereof in a vertical direction.