JP4404503B2 - Artificial tooth root - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an artificial tooth root, and more particularly to an artificial tooth root having a function of immediate load or early load.
[0002]
[Prior art]
Conventionally, an artificial tooth root having a self-tapping screw formed on the outer periphery has been used as the artificial tooth root.
[0003]
This artificial tooth root has the merit that the artificial tooth root can be placed under load immediately or early because the screw thread and jawbone are in close contact with each other from the beginning of implantation, and the burden on the patient is small.
[0004]
FIG. 4 shows an example of a conventional artificial tooth root 30 in which a self-tapping screw is formed.
[0005]
The tip side of the artificial tooth root 30 is a dome-shaped portion 32. Thus, by making the tip side into the dome-shaped portion 32, the load can be dispersed, and bone resorption due to stress concentration can be prevented from occurring in this portion.
[0006]
In the screw 31 of the artificial tooth root 30, both the crest diameter and the trough diameter are substantially constant, and the screw 31 is not formed in the dome-shaped portion 32.
[0007]
[Problems to be solved by the invention]
However, in the conventional artificial tooth root 30 provided with the self-tap type screw 31, the screw 31 is not formed in the dome-shaped portion 32, so that sufficient fixing force with the bone cannot be obtained in this portion. It was. Therefore, the initial fixing force is somewhat small, and there is a risk of sinking with a large load.
[0008]
Further, the screw 31 had a substantially constant peak diameter and valley diameter, and the most advanced screw height. Therefore, when the artificial tooth root 30 is screwed into the artificial tooth root insertion hole formed in the jawbone, a considerably large torque is applied when the tip of the screw first starts cutting the jawbone. This was very troublesome for the surgeon.
[0009]
Furthermore, the conventional artificial tooth root 30 does not have means for aligning the insertion direction of the artificial tooth root 30 with the axis of the artificial tooth root insertion hole when the artificial tooth root 30 is screwed into the artificial tooth root insertion hole. Therefore, there has been a problem that a very large torque is applied from the beginning to the end of the work when the screw is inserted at an angle with respect to the insertion hole.
[0010]
In view of such a problem of the prior art, in the present invention, a sufficiently large immediate or early fixing force can be obtained, subsidence due to a load can be prevented, and an artificial tooth root insertion hole formed in the jawbone can be artificially inserted. To provide an artificial tooth root in which when the tooth root is screwed in, the torque when the tip of the screw first starts cutting the jawbone is small, and the insertion direction of the artificial tooth root can be matched with the axis of the artificial tooth root insertion hole With the goal.
[0011]
[Means for Solving the Problems]
To solve the above problems, an earlier end side dome, and the dental implant its rear end is provided intraosseous implantation portion is substantially cylindrical, the outer circumferential surface of the intra-osseous implantation part, self-tapping The screw thread is formed between the outer peripheral surface and the top surface of the screw thread, and the surface on the tip side of the screw thread is continuous with a concave curved surface. The top surface of the screw thread is inclined toward the axial center toward the tip side .
[0012]
According to the artificial tooth root having such a structure, since the screw is also formed in the dome-shaped portion, the fixing force with the bone is improved.
[0013]
Further, since the dome-shaped portion is provided with at least one screw thread whose top is located outside the screw valley behind the dome-shaped portion, the artificial tooth root formed in the jawbone is used as the artificial tooth root. When screwing into the insertion hole, only a small torque is applied because the amount of bone to be shaved when the tip of the screw first starts cutting the jawbone is small.
[0014]
In addition, when the top of the screw thread formed in the dome-shaped portion is not located outward from the screw valley behind the dome-shaped portion, these screw threads are the opening edge of the artificial tooth root insertion hole. Will not engage, and the above-mentioned action will not be achieved.
[0015]
Further, in the artificial tooth root of the present invention, the most advanced screw thread as described above formed in the dome-shaped portion has a taper of 6 ° to 12.5 ° toward the shaft side of the artificial tooth root toward the tip. It has a tapered top surface that is inclined at an angle.
[0016]
This state-of-the-art screw thread serves as means for aligning the insertion direction of the artificial tooth root with the axis of the artificial tooth root insertion hole by the tapered top surface.
[0017]
That is, the state-of-the-art screw thread first comes into contact with the opening edge of the artificial tooth root insertion hole and slightly pushes the opening edge. Here, the opening edge of the bone deforms according to this taper shape, but as a reaction on the bone side to balance the load, even if the direction of the artificial root is inclined, the axis of the artificial tooth root insertion hole is generally The direction of the artificial tooth root is corrected so as to match the direction (self-centering action). Then, the screw cutting gradually begins when the direction of the artificial tooth root is corrected in this way.
[0018]
Here, when the taper angle is less than 6 °, such self-centering action is insufficient. On the other hand, if the angle exceeds 12.5 °, threading starts before self-centering, and there is a possibility that such an effect may not be achieved.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
1 to 3 show an artificial tooth root of the present embodiment. The artificial tooth root 1 has a substantially cylindrical shape, and a self-tapping screw 2 is formed on the outer periphery thereof.
[0022]
As the material of the artificial root 1, a biologically safe metal material such as Ti-6Al-4V alloy or pure titanium is used. The surface is preferably subjected to a treatment for increasing the affinity between the surface and bone, such as anodic oxidation, hydroxyapatite spraying, sandblasting, and titanium spraying.
[0023]
The artificial tooth root 1 is for a one-time method. The portion where the screw 2 is formed and the dome-shaped portion 5 on the distal end side are the bone-embedded portion 3, and the rear end side of the bone-embedded portion 3 is an abutment 4 that contacts the gingiva. Yes. The abutment 4 has a diameter larger than that of the intraosseous portion 3.
[0024]
Further, the screw 2 has substantially constant crest and trough diameters at the central portion 2b and the rear end portion 2c.
[0025]
On the other hand, a screw thread 20 is also formed in the dome-shaped portion 5 at the tip 2 a of the screw 2. Here, the dome-shaped portion 5 means that the top surface of the screw thread 20a or the outer peripheral surface of the artificial tooth root where the screw 2 is not formed is the top surface 23a of a plurality of screw threads indicated by a two-dot chain line m in FIG. A part that is inward of the connecting virtual line.
[0026]
The top of the screw thread 20a of the dome-shaped portion 5 is located outward from the screw valley behind the dome-shaped portion 5.
[0027]
As shown in FIG. 2, the screw thread 20a formed in the dome-shaped portion 5 has a tapered top surface 23a which is inclined at a taper angle β of 6 ° to 12.5 ° toward the shaft toward the tip side.
[0028]
Further, a concave step portion 6 is formed on the tip end side of the tapered top surface 23a of the screw thread 20a.
[0029]
According to the configuration of the screw thread 20a formed in the dome-shaped portion 5 as described above, when the artificial tooth root 1 is screwed into the artificial tooth root insertion hole formed in the jaw bone, the tip of the screw 2 first inserts the jaw bone. Since the cutting depth when starting to cut is small, the work can be started with a small torque.
[0030]
Further, the screw thread 20a of the dome-shaped portion 5 has a taper top surface 23a inclined at a taper angle β of 6 ° to 12.5 ° toward the axial side of the artificial tooth root 1 toward the tip side.
[0031]
The screw thread 20 serves as means for aligning the insertion direction of the artificial tooth root 1 with the axis of the artificial tooth root insertion hole by the tapered top surface 23a having the taper angle β.
[0032]
That is, the state-of-the-art screw thread 20a first comes into contact with the opening edge of the artificial tooth root insertion hole and slightly pushes the opening edge. Here, the opening edge of the bone is deformed corresponding to this taper shape, but as a reaction on the bone side for balancing the load, even if the direction of the artificial tooth root 1 is inclined, the artificial tooth root insertion hole is generally The direction of the artificial tooth root 1 is corrected so as to match the axial direction (self-centering action). Then, the screw cutting gradually starts from the point where the direction of the artificial tooth root 1 is corrected in this way.
[0033]
Here, when the taper angle is less than 6 °, such self-centering action is insufficient. On the other hand, if the angle exceeds 12.5 °, threading starts before self-centering, and there is a possibility that such an effect may not be achieved.
[0034]
2, the screw thread 20a of the dome-shaped portion 5 has a flare angle (end spread angle) α between the screw valley 22 on the rear end side and the concave step portion 6 on the front end side of 3 ° to 10 °. Set to °.
[0035]
If the flare angle α is less than 3 °, the stepped recess 6 is lowered, and there is a possibility that the function of preventing sinking may not be sufficiently achieved. On the other hand, if the flare angle exceeds 10 °, the area of the spherical surface of the dome-shaped portion 5 becomes small, and there is a possibility that the effect of preventing sinking may not be sufficiently achieved.
[0036]
Note that the dome-shaped portion 5 may be provided with a screw thread whose top is not located outside the screw valley behind the dome-shaped portion 5.
[0037]
In that case, the screw thread 20a formed in the dome-shaped portion 5 has a top position outside the screw valley behind the dome-shaped portion, and the tip of the most advanced screw thread 20a is the tip. It is important to form a tapered top surface 23a that is inclined toward the axial side of the artificial tooth root 1 at a taper angle β of 6 ° to 12.5 °.
[0038]
Next, FIG. 3 is an enlarged view showing a vertical sectional shape of the screw 2.
[0039]
As shown in FIG. 3, the screw thread 20 of the screw 2 has an R-curved tip side surface 21 that is continuous with a screw valley 22 and a screw top surface 23.
[0040]
The tip side surface 21 is a surface that receives a load in the bone. However, the tip side surface 21 is an R-curved surface, disperses the stress, and reduces the load applied to the bone by the angular edge of the screw top surface 23. Thereby, the induced bone resorption can be effectively prevented.
[0041]
In addition, this configuration of the screw thread 20 effectively prevents bone resorption, and in particular, increases the support fixing force of the screw thread 20 by cortical bone. Therefore, subsidence of the artificial tooth root 1 is eliminated.
[0042]
In addition, when the subsidence occurs in the artificial tooth root 1, the artificial tooth root 1 gradually starts to shake, causing bone resorption. When bone resorption occurs, a gap is formed between the artificial tooth root 1 and there is a risk of bacterial infection.
[0043]
On the other hand, the artificial tooth root 1 can reinforce the above-mentioned subsidence preventing action because the tip side surface 21 of the screw thread 20 has an R curved surface as described above so that bone resorption is unlikely to occur.
[0044]
As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to these embodiment, It cannot be overemphasized that it can be set as arbitrary forms, unless it deviates from the objective of invention.
[0045]
For example, in the above-described embodiment, the one-time artificial tooth root 1 has been described, but the artificial tooth root of the present invention may be used twice.
[0046]
【The invention's effect】
As described above, according to the artificial tooth root of the present invention, a sufficiently large fixing force can be obtained immediately or early, and sinking due to a load can be prevented. This eliminates the risk of bone resorption or bacterial infection.
[0047]
Moreover, when screwing into the artificial tooth root insertion hole formed in the jawbone, the torque when the tip of the screw first starts cutting the jawbone is small.
[0048]
Further, the insertion direction of the artificial tooth root can be aligned with the axis of the artificial tooth root insertion hole.
[0049]
These facilitate the surgical procedure.
[Brief description of the drawings]
FIG. 1 is a side view of an artificial tooth root of the present invention.
FIGS. 2A and 2B are partial enlarged views of the artificial tooth root of FIG.
FIG. 3 is a partial enlarged cross-sectional view of the artificial tooth root of FIG. 1;
FIG. 4 is a side view of a conventional artificial tooth root.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Artificial root 2 Screw 2a Tip part 2b Center part 2c Rear end part 3 Bone embedded part 4 Abutment 5 Dome-like part 6 Concave step part 20 Screw thread 20a Screw thread 21 Tip side surface 22 Screw valley 23 Screw top surface 23a Taper Top surface α Flare angle β Taper angle

Claims (1)

In an artificial tooth root provided with an intraosseous portion in which the distal end side is dome-shaped and the rear end side is substantially cylindrical,
On the outer peripheral surface of the bone-embedded part, a self-tapping screw thread is formed,
The surface on the tip side of the screw thread between the outer peripheral surface and the top surface of the screw thread is continuous with a concave curved surface,
An artificial tooth root, wherein a top surface of the screw thread located on the most distal side is inclined toward the axial center side in the side view .

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