KR100860265B1 - Dental fixtures - Google Patents

Abstract

The present invention relates to a dental fixture, and more particularly, in the dental fixture is inserted into the bone tissue consisting of cortical bone and spongy bone as the rotation around the central axis to form an artificial tooth, a plurality of the outer peripheral surface implanted in the cortical bone A first portion in which a first screw thread is formed; And a second portion implanted in the cavernous bone and having a plurality of second screw threads formed on an outer circumferential surface thereof, wherein a vertical distance between a vertex of the first screw thread and a central axis is smaller than a vertical distance between a vertex and a central axis of the second screw thread. As a fixation fixture, it not only reduces the pressure on the cortical bone, but also has the effect of preventing bone resorption and promoting bone fusion between the fixture and bone tissue.

Description

Dental fixtures {Dental fixture}

The present invention relates to a dental fixture, and more particularly to a dental fixture for relieving the pressure applied to the cortical bone to prevent bone resorption and promote bone fusion.

Screw-type fixtures used in dentistry are inserted into bone tissue to form an artificial tooth root. When the fixture is inserted into bone tissue and fuses with surrounding bone tissue, the abutment is combined thereon, and an artificial tooth prosthesis is made therein. Will be. The fixture is made of titanium to improve the compatibility with the surrounding bone tissue, and a thread is formed on the outer circumferential surface of the fixture body from the top to the bottom, it is used as a fixing member for fixing the prosthesis of the orthopedic as well as dental. Meanwhile, the bone tissue into which the fixture is inserted is composed of cortical bone and spongy bone. The spongy bone is a relatively soft bone tissue of the bone, and the cortical bone is harder than the spongy bone and generally forms a relatively thin film surrounding the spongy bone. When the fixture is inserted into the bone tissue and placed, the length of the portion in contact with the cancellous bone is longer than the length of the portion in contact with the cortical bone.

Bone absorption is one of the biggest problems when using common screw-type fixtures. Bone resorption refers to the phenomenon of degeneration as the amount of bone tissue around the fixture is reduced. Such bone resorption may weaken the fixation force of the fixture, thereby inhibiting the stability of the prosthesis and causing breakage of the prosthesis.

In particular, bone resorption may deposit inflammation-causing calculus in the gum tissue surrounding the fixture when the fixture is used for dental use, or may grow down the gum tissue along the exposed end of the fixture. Therefore, bone resorption is not preferable because it not only inhibits the stability of the prosthesis, but also does not look good.

The biological cause of bone resorption has not yet been elucidated. However, the stress acting on the adjacent bone tissue of the fixture is unevenly distributed, and both the condensation pole and the low pole due to the stress concentration are recognized to promote bone resorption.

In addition, according to the shape of the thread forming the outer circumference of the fixture, when placing a lot of pressure on the cortical bone and the cancellous bone when implanted, it is recognized that the problem of bone absorption due to excessive compression.

In particular, in general fixtures, the threads provided on the outer circumferential surface are arranged in the same size at equal intervals from the upper end to the lower end. However, such a general fixture is not preferable because it does not properly consider the characteristics of the hard cortical bone and the soft sponges, the problem of the above-mentioned bone absorption occurs seriously. In order to solve the problem of bone absorption, Korean Patent Laid-Open Publication No. 2001-0071941 (hereinafter referred to as "prior art 1") divides a screw thread into a first axial portion 110 and a second axial portion 120 , So that the axial spacing la between the peaks of adjacent peaks in the first axial direction portion 110 is less than the axial spacing lb between the vertices of adjacent peaks in the second axial direction portion. One insert 100 is disclosed. The reason why the intervals between the vertices of the first axial portion 110 and the second axial portion 120 are different from each other is that in the second axial portion 120, large threads are relatively soft sponges (not shown). This insertion serves as a foundation fixation, the first axial portion 110 is inserted into the hard cortical bone small thread to prevent stress concentration and evenly distribute the load to the adjacent bone tissue to prevent bone absorption.

On the other hand, the Republic of Korea Patent Publication No. 2006-0061415 (hereinafter referred to as "prior art 2") is provided with a tubular portion 110 in contact with the cortical bone, the body portion 120 in contact with the cancellous bone, the height is in the body portion Disclosed is a technique in which different first uneven portions 121 and second uneven portions 122 are alternately formed to evenly distribute the load applied by the fixture 100 in bone tissue, particularly in the sponge bone. have.

On the other hand, in order to insert the above-described fixture into the bone tissue, a drill hole of an appropriate size is first formed in the bone tissue using a drill, and then a screw groove is made in the inner circumferential surface of the recess, while inserting the fixture in the hole. The outer diameter of the recess is not formed to correspond to the valley of the thread formed on the outer circumferential surface of the fixture to be inserted, but to correspond to the intermediate point between the vertex and the valley in consideration of insertion convenience (see line ld of FIG. 1). After insertion, a void is created between the thread of the fixture and the bone tissue (because the outer diameter of the hole is not formed in the bone tissue so that it corresponds to the bone). This void is filled by the bone tissue over time, and the fixture and bone tissue become loose. Are fused to each other.

Such a fixture according to the prior art 1 and the prior art 2 has the following problems.

First, both the prior art 1 and the prior art 2 divide the fixture into an upper end and a lower end, a small thread is arranged on the upper side, and a large thread is arranged on the lower side. However, when a small thread is inserted into the bone tissue after the large thread is inserted when the fixture is inserted into the bone tissue, the rotation torque suddenly becomes excessively large. That is, the lower end of the fixture first forms a large screw groove on the inner circumferential surface of the buried hole, and then, as the upper end of the fixture is inserted, a new small thread is formed around the preformed large screw groove, in which the rotational torque suddenly increases. The increase in the rotational torque is applied to a considerable degree of pressure on the bone tissue not only inhibits the bone fusion, there is a problem that promotes bone absorption.

In addition, the buried hole in the prior art has an outer diameter corresponding to the midpoint between the top of the thread and the bottom of the valley as described above, as shown in Figure 1, the distance from the bottom of the valley to the outer diameter of the buried hole ( e) is large, so there is a lot of free space. Accordingly, it takes a long time for the bone tissue to grow to the bottom of the bone, causing bone fusion to be delayed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a dental fixture that is inserted and implanted while minimizing the pressure on the cortical bone.

Dental fixture of the present invention for achieving the above object is inserted in the bone tissue consisting of cortical bone and spongy bone as the rotation around the central axis to form an artificial tooth, implanted in the cortical bone and a plurality on the outer peripheral surface A first portion of the first screw thread is formed; And a second portion implanted in the cancellous bone and having a plurality of second screw threads formed on an outer circumferential surface thereof, wherein a vertical distance between a vertex of the first screw thread and a central axis is smaller than a vertical distance between a vertex and a central axis of the second screw thread. It is characteristic.

In the dental fixture, the vertices of each thread of the first portion are preferably spaced apart from the central axis by the same distance.

In the dental fixture, the vertices of each thread of the second part are preferably spaced apart from the central axis by the same distance.

In the dental fixture, the vertical distance between the vertex of the thread of the second part and the valley adjacent to the vertex is preferably greater than the vertical distance between the vertex of the thread of the first part and the bone adjacent to the vertex.

In the dental fixture, the vertical distance between the vertex and the central axis of the second screw thread is preferably larger by 0.02 to 0.3 mm than the vertical distance between the vertex and the central axis of the first screw thread.

In the dental fixture, in the plurality of threads of the first portion, the axial distance between the vertices of the threads adjacent to each other is preferably 0.1 to 0.5 mm.

The dental fixture of the present invention having the above-described configuration, by reducing the outer diameter of the screw implanted in the cortical bone smaller than the outer diameter of the screw implanted in the spongy bone, less pressure on the bone tissue of the cortical bone, less pressure, and prevents bone absorption In addition, it has the effect of promoting bone fusion between fixture and bone tissue while suppressing bone resorption.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a cross-sectional view of a dental fixture according to a preferred embodiment of the present invention, Figure 4 is a graph comparing the mounting torque of the fixture according to the prior art of Figure 1 and the present invention according to FIG.

The dental fixture 10 according to the present embodiment is inserted into a bone tissue (not shown) including a cortical bone (not shown) and a cancellous bone (not shown) to form an artificial tooth root. The fixture 10 has a cylindrical shape as a whole, and threads are formed on the outer circumferential surface thereof. When the dental fixture 10 is rotated along its central axis, the dental fixture 10 is inserted into the cortical bone and the cancellous bone while being formed while forming a screw groove (not shown) on the inner circumferential surface of the buried hole provided in the bone tissue by a drill (not shown). In this case, the material used as the fixture 10 is generally used as a dental fixture is preferably made of titanium, in addition, if there is no rejection to the human body it is also possible to use other kinds of metal material. The fixture 10 of this embodiment includes a first portion 20 and a second portion 30. The first part 20 refers to a part where most of the first part 20 is placed in the cortical bone when the fixture 10 is inserted (however, a lower part of the first part 20 may be placed in the cancellous bone). The upper side of 10) is formed. The first portion 20 is provided with a plurality of first screw threads 21 formed with a vertex 21a and a valley 21b.

The insertion depth at which the first portion 20 is inserted when the central axis C of the first screw thread 21 is rotated once is referred to as “L1”. The vertical distance between any one vertex 21a of the first screw thread 21 and the valley 21b adjacent to the vertex 21a is referred to as the first height h1. In addition, the vertical distance between the central axis C of the first screw thread 21 and the vertex 21a is R1, and the outer diameter of the first screw thread 21 is D1. The vertices 21a of the first screw thread 21 are spaced apart by the same distance from the central axis C, and the straight lines connecting the vertices 21a are preferably parallel to the central axis C.

In addition, the axial distance l ₁ between the vertices 21a of the first screw threads 21 adjacent to each other in the first portion 20 is preferably 0.1 to 0.5 mm, more preferably 0.4 mm. It is good. When the axial distance l ₁ is smaller than 0.1 mm, the first screw thread 21 is increased in the first portion 20 and the implantation torque is excessively increased, thereby exerting excessive pressure on the cortical bone. In addition, when the axial distance is larger than 0.5 mm, the number of the first screw threads 21 is small, and there is a concern that the apex 21 a of the first screw threads 21 exerts excessive stress on the cortical bone. The thread 21 must be properly provided so that excessive stress is not concentrated in any part of the cortical bone and the stress is properly distributed throughout the cortical bone.)

The second portion 30 is implanted in the cancellous bone and a plurality of second screw thread 31 is formed on the outer circumferential surface. This second portion 30 forms the lower side of the fixture 10. (However, some of them may be placed in the cancellous bone.) The depth of implantation of the second portion 30 when one turn is turned about the central axis C of the second portion 30 is the lead distance. L2 ". The vertical distance between any one vertex 31a of the second screw thread 31 and the valley 31b adjacent to the vertex 31 is called the second height h2.

. In addition, the vertical distance between the center axis C of the 2nd screw thread 31 from the vertex 31a is called R2, and the outer diameter of the 2nd screw thread 31 is called D2. The vertices 31a of the second screw thread 31 are spaced apart by the same distance from the central axis C, and the straight lines connecting the vertices 31a are preferably parallel to the central axis C.

Meanwhile, the vertical distance (radius R1) between the vertex of the first screw thread 21 of the first part 20 and the central axis C is the vertex and the center of the second screw thread 31 of the second part 30. It is preferred to be smaller than the vertical distance (radius R2) between the axes C (R1 < R2). As such, the reason for making the vertical distance R1 of the first portion 20 smaller than the second portion 30 is that the first portion 20 is inserted after the second portion 30 of the fixture 10 is inserted. This is to minimize the increase in the mounting torque due to the increase in the number of threads when inserted. If the vertical distance between the second part and the first part is the same as in the prior art, excessive stress will be concentrated in the cortical bone due to the rapid increase of the insertion torque. (This has been proved in an experiment to be described later.) In this embodiment, the vertical distance of the first portion 20 is smaller than that of the second portion 30, so that when the first portion 20 is inserted after the second portion 30 is inserted, The increase can be prevented.

On the other hand, the vertical distance (R1) of the first portion 20 is preferably smaller by 0.02 ~ 0.3mm than the vertical distance (R2) of the second portion 30, and more preferably smaller by 0.05 ~ 0.15mm It is good, and most preferably, as small as 0.1mm. If the difference between the two is smaller than 0.02, there is little difference between the first portion 20 and the second portion 30, and there is a fear that the reduction of the insertion torque to be achieved is hardly achieved. In addition, when the difference between the two is increased by 0.3 mm, the distance h1 between the apex of the first screw thread 21 protruding from the outer circumferential surface in the first portion 20 and the valley is small, so that the function as a screw is lost. There is a concern that the supporting force for supporting the bone tissue is weakened, and since the empty space between the surface of the first portion 20 and the bone tissue is large after implantation, the amount of bone tissue that needs to grow to the surface of the first portion 30 later increases. It may take a long time to recover after the procedure.

Further, the first height h1, which is the vertical distance between the apex 21a of the first screw thread 21 of the first part 20 and the apex 21b adjacent to the apex 21a, is the second part 30. The second height h2, which is the vertical distance between the apex 31a of the second screw thread 31 and the apex 31a and the adjacent valley 31b, is preferable. This absorbs a large amount of bone tissue between the second screw thread 31 in the second portion 30 to be inserted first, thereby strengthening the initial supporting force, and the second portion 30 in the first portion 20 inserted later. Instead of absorbing a small amount of bone tissue, the stress is evenly distributed to the cortical bone to prevent stress concentration.

The lead distance L1 of the first portion 20 is equal to the lead distance L2 of the second portion 30, so that the same rotation is performed even if the first portion 20 is inserted after the second portion 30 is inserted. It is preferable to be inserted into the bone tissue by the same distance with respect to the number (L1 = L2).

In addition, reference numeral 40 denotes a third part, and the third part 40 is a part forming the lower end of the fixture 10, and has a plurality of third thread threads 41 having an outer circumferential surface of a substantially conical shape. The grooves 42 are preferably formed in the vertical direction along the vertical direction.

The dental fixture 10 according to this embodiment is placed in the bone tissue of the human body as follows.

First, using a drill, a drilled hole having the drill line of FIG. 3 having an outer diameter Dd1 is formed in the alveolar bone to be implanted. Subsequently, a predetermined tool is used to be inserted into the implantation hole of bone tissue while rotating about the central axis C of the dental fixture 10. At this time, the dental fixture 10 forms a plum hole of an appropriate size by inserting the third portion 40 which performs the self-tapping function first, and then the second portion 30 having a large thread is inserted into the recess. While being inserted, a screw groove having a predetermined size is formed on the inner circumferential surface of the recess. After the second portion 30 is inserted, the first portion 20 is continuously inserted and inserted into the buried hole while additionally creating a new small screw groove in the screw groove formed by the second screw thread 31. When the insertion is completed, there is a suitable void space between the surface of the first portion 20 or the second portion 30 and the inner peripheral surface of the buried hole, which is the tissue of the sponges and cortical bone grow over time The fixture 10 and the bone tissue placed while being filled are fused to each other.

At this time, the dental fixture 10 according to the present embodiment is applied to the cortical bone because there is no sudden increase in the insertion torque in the process of inserting the first portion 20 having a different screw shape after the second portion 30 is inserted. Less pressure That is, since the outer diameter of the first screw thread 21 of the first portion 20 is smaller than the outer diameter of the second screw thread 31 of the second portion 30, the amount of pressure applied to the bone is minimized to promote bone fusion. Has

On the other hand, the applicant has carried out the following experiment to prove that the technique according to this embodiment is less pressure on the cortical bone compared to the prior art.

<Comparison Experiment of Rotational Torque When Planting>

This comparison experiment is when inserting the fixture 10 according to the present embodiment and the fixture 100 according to the prior art shown in Figure 1 in an environment similar to the bone tissue of the human body, by measuring and comparing the rotation torque, respectively, the overall placement torque It was carried out to observe the changing behavior of the.

For the experiment, an implantation target (not shown) in which the fixture 10 is placed, and fixtures 10 and 100 to be implanted in the implantation target are prepared. In addition, a drill (not shown) for forming a buried hole in the implantation object, a rotary tool for rotating the fixtures 10 and 100, and a torque measuring device (not shown) for measuring the torque are also prepared at the same time.

The implantation target consists of an upper portion (thickness: 3mm, bone density: 50 g / cm ² ) corresponding to the cortical bone, and a lower portion (thickness: 27mm, bone density: 30g / cm ² ) disposed below the upper portion. It is similar to the environment of the bone tissue of the actual human body.

In addition, the fixtures 10 and 100 prepared two types. The first type is a fixture 10 having the same shape as the fixture of this embodiment, and the second type is a fixture 100 having the same shape as the fixture shown in the prior art shown in FIG.

The specification of the fixture 10 according to the present embodiment is as follows.

-Axial length from top to bottom (Lt1): 11.5mm

-Outer diameter D1 of the first portion 20: 3.8 mm

-Lead L1 of the first screw thread 21 in the first part 20: 0.8 mm

-First height h1 of the first screw thread 21: 0.2 mm

-Outer diameter D2 of the second portion 30: 4.0 mm

-Lead L2 of the second threaded thread 31 in the second part 30: 0.8 mm

-Second height (h2) of the second screw thread (31): 0.35

In addition, the specification of the fixture 10 according to the prior art shown in FIG.

Axial length (Lt) from top to bottom: 11.5mm

Outer diameter (D): 4mm

Lead L of thread 111 of first portion 110: 0.8 mm

-Height (h) of thread 111 of the first portion 110: 0.2mm

Using these conditions, the experiment was performed as follows.

First, a buried hole is formed to have a diameter (Dd, Dd1) of 3.6mm in the implantation target corresponding to the bone tissue. Subsequently, while inserting the fixture 10 according to the present embodiment and the fixture 10 according to the related art shown in FIG. 1, respectively, are inserted into different buried holes, the rotational torque according to the implantation depth is measured. The experimental results are as shown in FIG.

Referring to FIG. 4, after the second part 120 is inserted, the fixture 100 according to the related art sharply increases the rotation torque at the 8.5 mm point at which the first part 110 starts. (A sharp rise from 26Nm to 40Nm.)

On the contrary, after the second portion 30 is inserted, the fixture 10 according to the present embodiment rises slowly at the 8.5 mm point at which the first portion 20 starts, and thereafter, the sudden increase in rotational torque is performed. Rotational torque is increased slowly without (the gentle rise of mounting torque from 26Nm to 27.5Nm).

As such, in the present embodiment, unlike the prior art, there is no sudden increase in the insertion torque between the transition portion to the second portion 30 and the first portion 20, and thereafter, the rotation torque gradually increases to the cortical bone as a whole. There is no sudden increase in torque, which results in significantly less pressure on the cortical bone during placement. Accordingly, it can be inserted into the bone tissue without damage and can be inserted without damaging the bone tissue, especially the cortical bone, there is an advantage that can promote bone fusion.

On the other hand, the present embodiment has the following effects in addition to the above-described effects.

First, the diameter of the buried hole is formed to correspond to the mid-point of the top of the screw thread and the valley as described above. Therefore, in the prior art shown in Fig. 1, that is, a hole is drilled so that the outer diameter Dd of the buried hole is located approximately at an intermediate point between the valley bottom and the vertex of the thread. Therefore, the distance to e) becomes e.) Therefore, when the fixture 10 is inserted into the bone tissue, the bone tissue is not filled from the bottom of the bone to the implantation line ld, as described above. However, when the void becomes large, there is a problem that it takes a long time for the bone tissue to grow.

On the contrary, in the present embodiment, since the small thread is provided in the first portion 20, a buried hole having the outer diameter Dd1 at the midpoint between the peak of the small thread and the valley is formed in the bone tissue. Accordingly, as compared with the prior art, the distance f between the bottom of the valley and the outer diameter line ld1 of the buried hole is shorter than in the prior art. (F <e)

That is, in this embodiment, since the outer diameter line ld1 of the buried hole is located close to the valley of the thread, the portion where the bone tissue is not occupied between the thread and the valley is minimized. Accordingly, not only the bone tissue is quickly fused with the fixture 10, but also has the advantage of being surely combined with the fixture 10.

In addition, after being inserted and implanted, the partial stress concentration may be dispersed in the first portion 20 to prevent sudden absorption, as well as to improve bone fusion.

In addition, while having the above-mentioned advantages and has a sufficient contact area with the bone tissue has an advantage of excellent binding force to the bone tissue.

In addition, by dispersing the stress concentration on the cortical bone to the spongy bone to distribute the stress evenly throughout the fixture 10 has the effect of preventing bone absorption of the cortical bone and promote bone fusion.

Such, the fixture 10 according to the present embodiment may be modified as follows to achieve the object of the present invention.

First, in the above-described embodiment, the vertices 21a of the first screw thread 21 are spaced apart from the central axis C by the same distance, or the vertices 31a of the second screw thread 31 are the central axis C. Although spaced apart from each other by the same distance, it is also possible to change or change the distance between the vertices (21a, 31a) and the central axis (C) toward the upper or lower side in the axial direction. That is, even within the same first portion 20 or the second portion 30, it is also possible that threads having different distances between the central axis C and the vertices 21a and 31a are arranged together.

In addition, in the above-described embodiment, the distance between the vertices C and the vertices of all the first screw threads 21 of the first portion 20 is lower than that of all the second screw threads 31 of the second portion 30. Although it has been described that the size is small, it is also possible that a part of the first screw thread 21 of the first part 20 is larger than a part of the thread of the second part 30.

In addition, in the above-described embodiment, the first screw thread 21 has been described as being a single thread, but of course, it is also possible to use a two-thread thread or more than a multi-thread thread.

In addition, in the above-described embodiment, the vertical distance between the apex 21a of the first screw thread 21 of the first portion 20 and the apex 21a and the adjacent valley 21b is determined by the second portion 30. Although it was demonstrated that it is smaller than the vertical distance between the vertex 31a of the two-threaded thread 31, and the vertex 31a and the adjacent trough 31b, it is also possible that the mutual vertical distance is the same. For example, if the outer diameter of the first portion 20 is smaller than the outer diameter of the second portion 30, the distance between the vertex and the valley may be the same.

Although the present invention has been described in detail with reference to Examples and Modifications, the present invention is not necessarily limited to these Examples and Modifications, and may be variously modified and implemented within the scope without departing from the spirit of the present invention. .

1 is a schematic diagram of a fixture according to the prior art

2 is a cross-sectional view of another fixture according to the prior art.

3 is a schematic diagram of a fixture according to an embodiment of the present invention;

4 is a graph showing the results of a comparative experiment between the fixture of FIG. 1 and the fixture of FIG.
5 is a schematic diagram of a fixture according to another embodiment of the present invention.

<Detailed Description of Drawings>

10 ... fixture 20 ... part 1

21 ... 1st thread 30 ... 2nd part

31.2nd thread

Claims (7)

In the dental fixture (10) is rotated about the central axis (C) is inserted into the bone tissue consisting of cortical bone and spongy bone to form an artificial tooth root, The first screw thread 21 is formed on the outer circumferential surface of the cortical bone, and the vertical distance between the vertex 21a of the first screw thread 21 and the vertex 21b adjacent to the vertex 21b is the first height. a first portion 20 that is (h ₁ ); And The second screw thread 31 is formed on the outer circumference and implanted in the cancellous bone, and the vertical distance between the vertex 31a of the second screw thread 31 and the vertex 31b adjacent to the vertex 31b is the first distance. Have a second portion 30 that is a second height h ₂ greater than the height h ₁ , The vertical distance R ₁ between the vertex 21 a of the first screw thread 21 and the central axis C is the vertical distance between the vertex 31 a and the center axis C of the second screw thread 31. R ₂ ) is a dental fixture, characterized in that as small as 0.02 ~ 0.25mm. The method of claim 1, Dental fixtures, characterized in that the vertices (21a) of each of the first screw thread (21) of the first portion (20) are spaced apart from the central axis (C) by the same distance. The method of claim 1, Dental vertex, characterized in that the vertices (31a) of each of the second screw thread (31) of the second portion (30) are spaced apart from the central axis (C) by the same distance. delete delete The method of claim 1, In the plurality of first threaded threads (21) of the first portion (20), the axial distance between the vertices (21a) of the adjacent threads (21) is 0.1 to 0.5 mm. The method of claim 1, In the first portion 20, the vertical distance R ₁ between the vertex 21a of the first screw thread 21 and the central axis C is the first portion 20 from the upper end of the first portion 20. Dental fixtures, characterized in that the reduction to the bottom.

Images