JPH07236645A - Artificial root of tooth - Google Patents

Abstract

PURPOSE:To improve a stress dispersing effect to a jaw bone by setting, in a specified range, an angle of the screw head of the screw part of an artificial root of a tooth provided with the screw part implanted in the jaw bone. CONSTITUTION:An artificial root 1 of a tooth is provided with a root part 3 provided with a screw part 2 implanted in a jaw bone, a head part 4 attached with a technical material and a neck part 5 connecting the root part 3 to the head part 4, preferably the root part 3 and the head part 4 are integrally molded as one axis. The root part 3 is provided with a hollow axis body 6 and a spiral- shaped screw part 2 projectingly formed on its perimeter and the screw head angle of the screw part 2 is set in a range from 60 deg. to 70 deg.. The axis body 6 is provided with a central hole 7 and window parts 8 are openingly formed on its right and left sides. And attaching sites of the neck of the neck part 5 with the head part 4 and with the root part 3 are made taper parts 9 which expand gradually toward the head part 4 and the root part 3. Thus, uniform stress dispersion is designed by bufferizing a load like occlusion power or the like appropriately and decreasing the stress concentration of the screw head tip part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial tooth root having a screw portion to be implanted in a jawbone, and more particularly to a technique for dispersing an occlusal force in the jawbone to reduce the burden on the jawbone.

[0002]

2. Description of the Related Art Conventionally, an artificial dental root having a threaded portion to be implanted in a jawbone is widely known as a spiral implant among screw implants, but the present inventor has found that this spiral implant is effective as a seismic resistant structure. I noticed that it is very similar to the "top type foundation" of civil engineering and building engineering, and I have tried to improve the spiral implant focusing on the theory of "top type foundation".

This spiral implant differs from other screw implants in the following points.

[0004] Conventional screw implants are unaware of the "top basic theory" and therefore have not been addressed at all.

That is, whether the screw has a ripple shape or a continuous sine curve, no concern about the "top-type foundation" is recognized.

In other screws, the depths of the ridges and valleys of the screw are shallow and small, and it is only considered that the screw is intended to be fixed vertically.

The surface structure of the implant itself is intended to have a surface area which is several times as large as that of a smooth surface by the plasma coating method or the like. The augmentation method is based on micro-cracking (Micr) when an occlusal force of about 50 [kg] acts on one implant in actual clinical practice.
There is a theory that micro-fractures of the alveolar bone occur and it is not effective, and this appears as an age-related subsidence phenomenon of the implant in the alveolar bone, and as a result, such implant It is believed that the surrounding bone has lost its absorption and has become less durable.

As is well known, the "top type foundation" is a top shape in which a mandrel is inserted through the center of a block body having a triangular cross section, and it is recognized as effective as a foundation material for soft ground. That is, the conical inclined surface of the block body disperses the load over the entire surrounding ground to increase the supporting force on the soft ground.

On the other hand, in the spiral implant, a spiral screw thread is projected around the shaft body, and this screw thread corresponds to the block body of the spinning top, and a compressive load is applied to the bone through the inclined surface of the screw thread. It is dispersed.

As a proposal for improving this type of spiral implant, the present inventor has already proposed the artificial tooth root described in Japanese Utility Model Publication No. 4-31048.

[0011]

However, in the conventional spiral implants described above, the degree of stress dispersion is insufficient, and the alveolar bone and the jaw bone are absorbed to reduce the residual bone mass, and the case where the residual bone mass decreases, We could not cope with patients with low bone mass and soft bones immediately after tooth extraction or no time after tooth extraction, and in elderly patients with osteoporosis.

[0012] However, such a case is also a non-adaptation of removable removable denture which is commonly used today, and a case where functional recovery by a fixed intraosseous implant is desirable for the purpose of effective function recovery. Is. There is a strong need and demand for the application of intraosseous implants only in cases where the alveolar bone is low or immediately after tooth extraction, and the purpose of enabling endosseous implants to be applied to soft residual jawbone with a limited amount and depth. Then, how to expand the range of adaptation remains a major issue.

The inventor of the present invention, based on the proposition that "how to utilize less jaw bones and soft jawbones to better disperse the occlusal force evenly in the jawbone immediately after planting", the hardness of the jawbone of the human body As a result of earnest research on physical properties of raw bone and mechanical interface characteristics between the implant and the raw bone, using a beef rib that is close to Surrounding and supporting the strength of the surrounding jawbone,
It is concluded that the stress is not directly connected to the effective distribution to the bone. ”Rather, it was found that the morphology of the implant, in particular, the angle of the thread of the threaded portion has a significant influence on the stress distribution.

Further, as a result of the occlusal force being applied to the implant, the implant body may break after several years due to metal fatigue with the passage of time, and it is necessary to improve the strength as well as the stress dispersion.

The present invention has been made to solve the above-mentioned problems of the prior art, and the purpose thereof is to:
Paying attention to the point that the thread angle has a significant influence on the stress distribution effect on the jawbone, the spiral with the optimum thread angle
To provide a type of artificial tooth root.

[0016]

In order to achieve the above object, according to the present invention, in an artificial root having a threaded portion to be implanted in the jawbone, the thread angle of the threaded portion is set to 6 degrees.
It is characterized in that it is set in the range of 0 ° to 70 °.

It is effective that the threaded portion is formed around the shaft body having the central hole.

Further, the diameter of the central hole of the threaded portion is set to 1.
By reducing the size from 8 [mm] to 1.6 [mm], strengthening was achieved against breakage of the screw part due to metal fatigue over time.

The threaded portion is characterized in that it is formed around a hollow shaft body having a central hole.

The shaft body is provided with a window portion communicating with the central hole.

The thickness of the neck portion connecting the screw portion to the head is
The diameter is made smaller than the outer diameter of the screw part so that the artificial root does not come into contact with cortical bone or compact bone in the initial stage of implantation, and the load is distributed only to the cancellous bone of the bone marrow where the screw part is embedded. It is characterized by doing.

It is characterized in that the thickness of the neck portion is set within a range of about 2 mm.

It is characterized in that the head has a modified cross-sectional shape that becomes narrower toward the tip so that directionality can be identified and rotational implantation can be performed.

It is characterized in that the head shape is a conical shape having one plane of a D-cut cross section.

It is characterized in that it has a structure in which a groove for a driver is formed at the head stump.

[0026]

The angle of the thread of the conventional artificial tooth root with a screw portion is set to about 77 °, while the inclination angle of the block body in civil engineering and construction is 4 from the theory of "top spinning type foundation".
It has been clarified that it is preferable to set the angle to 5 °, and in order to correspond to the screw thread, it is preferable to set the screw thread angle to about 90 ° in increments of about 45 ° in the vertical direction.

However, when actually tested, it was found that the artificial tooth root had the highest stress dispersion effect in the above-mentioned range of 60 ° to 70 ° instead of any of the above angles.

It is considered that the reason is that the jawbone in which the screw part is implanted has elasticity unlike the ground which is the foundation of construction and elastically deforms by the load. That is, unless the screw part implanted in the jawbone is deformed following the deformation of the jawbone to some extent, the contact portion becomes a partial contact, stress concentration occurs, and the bone tissue is destroyed at the stage of a small load.

That is, when the screw thread angle is large, the screw thread thickness is large, so that the rigidity of the screw thread portion is increased, and the occlusal force is not buffered in the screw thread portion and is applied to the bone tissue, resulting in local stress. It gets expensive.

On the other hand, when the screw thread angle is small, the thickness of the screw thread is small, so that the rigidity of the screw thread portion is small, and even if an occlusal force is applied, the screw thread portion is elastically deformed and the load acting on the bone tissue is reduced. It can be buffered to disperse stress. However, if the thread angle is too small, a cushioning effect is obtained, but the tip of the thread bites into the bone tissue and stress concentration occurs at the tip.

Then, as a result of intensive research, 60 ° to 70 °
By setting in the range of °, the load such as occlusal force could be appropriately buffered, and the stress concentration at the tip of the screw thread could be reduced as much as possible, and a uniform stress distribution effect could be obtained.

Further, by making the shaft of the screw part hollow so as to reduce the rigidity, it is possible to enhance the cushioning effect of the load such as the occlusal force in combination with the setting within the range of 60 ° to 70 °. The burden on the bone tissue can be reduced as much as possible.

In particular, a window opening structure provided with a window portion is effective for this effect.

A titanium-based material, which has good biocompatibility and is hard as a material, is suitable, but the flexibility and Young's modulus of the titanium material and the correlation between the Young's modulus of the cancellous bone are effective for stress distribution of load. This is an important condition for achieving If the titanium material is hard, it is not good, but the crystal structure is important.

The window-opening structure is effective in relation to the Young's modulus of the cancellous bone around the implant (artificial root) by the "soft structure". Other screw-type implants have no window or even have a "flexible structure".

On the other hand, if the shaft of the threaded portion has a hollow structure, the effect of stress dispersion is enhanced, but problems occur in strength and durability.

In this respect, the outer diameter of the thread is φ4.0 [mm]
When the root diameter (shaft diameter) is 2.4 [mm], the stress dispersion effect is maintained by changing the diameter of the central hole from φ1.8 [mm] to φ1.6 [mm]. In addition, we were able to realize an artificial dental root that is superior in strength and durability.

Further, the thickness of the neck portion connecting the screw portion to the head is made smaller than the outer diameter of the screw portion so that the implant (artificial root) body does not come into contact with cortical bone or compact bone at the initial stage of planting. By setting and setting the load on the cancellous bone of the bone marrow in which the screw portion is embedded and applying the load, an appropriate stress is applied to the bone tissue and the functional healing of the bone tissue is promoted.

Common sense In general, in order to maintain and stabilize the artificial tooth root in the early stage of planting, the head of the artificial tooth root is attached to the dense bone in order to apply an external force to the hard and tough cortical bone / compact bone. (Head) Base and neck are closely attached and fixed.

However, in the present invention, as its premise, no fixation is expected at all by maintaining contact with compact bone, and maintenance and fixation at the initial stage of planting are all required for the soft bone marrow / cancellous bone inside. .

Stable healing of the interface between the living body and the implant (artificial root) body is an important issue. However, it is important to maintain and fix the compact bone in general at the implant (artificial root) body of the present day at the initial stage of implantation. What is sought is that stress concentration on the periphery of the neck of the implant (artificial root) has a negative effect on the regeneration and healing of surrounding tissue, resulting in time-dependent bone resorption and accompanying downward proliferation of epithelial soft tissue. Microbial infection of soft tissues has become a major problem in long-term prognosis management.

On the other hand, when all of the maintenance and fixation at the initial stage of planting are required for the soft bone marrow / cancellous bone inside, on the contrary, the proliferation and addition of bone are recognized even in an unclean environment ( Photograph 7 of Case 2 of P.4 and Photograph 1 of Case 5 of P7 in the attached document "Clinical of Shell Chev Implants"
0, P. 8 and P.P. (See comparison of photos 7 and 14 in 9). The present invention has discovered the dimensions of the threads that most effectively distribute stress in such soft bone marrow tissue.

The neck thickness of about 2 mm is a thinness not found in other general artificial tooth roots.
In the prognosis management of the artificial tooth root after surgery, it does not require the nervous cleaning management like other artificial tooth roots. This is the "OGA-BAR" that the present inventor has been advocating for a long time.
It is based on theory.

The "OGA-BAR" theory is "prosthetically, the periodontal tissue has a width of 2.0 [mm] in contact with the adhered gingiva and is within a range of 2.0 [mm]. It can automatically maintain a durable health level. ” This greatly improves the way the temporary crown restoration and the final prosthesis relate to the soft tissue.

In terms of periodontology, when the diameter of the implant (artificial root) body greatly exceeds 2 [mm] to 4 [mm], the natural nature of the epithelium accompanying the metabolism of the epithelium near the adhesive interface with the epithelium It is known that shedding (self-cleaning action) becomes impossible, and as a result, it accumulates as old dirt, which causes the dirt near the interface, causes inflammation and infection, and triggers periodontal disease. Therefore, for the neck thickness of 2 [mm],
It has important significance and value in periodontology.

Due to the same self-cleaning action, the thickness of the head (head) is limited to about 3 [mm]. Further, the thickness of the implant (artificial tooth root) / neck portion (neck portion) is appropriately set to 2 [mm] in consideration of the relationship with the strength of bending stress.

In the present invention, the shape of the head is a conical shape having one plane of the D-cut cross section, so that the front and rear directionality can be easily discriminated.

Although it is also possible to use a hand key or the like to utilize a modified cross section of the artificial tooth root head to apply torque when implanting an artificial tooth root or the like, the hand key is provided on the side surface of the conical head. May bite. Therefore, it is preferable to provide a groove for receiving the bit of the driver in the stump of the head and apply a screwing torque to the head. This eliminates the possibility that the hand key will bite into the side of the head and will not come off.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. In FIG. 1 showing an artificial tooth root according to an embodiment of the present invention, reference numeral 1 denotes the entire artificial tooth root, and a root portion 3 provided with a screw portion 2 to be implanted in a jawbone is roughly attached to a technical product. A head 4 and a neck 5 connecting the root 3 and the head 4 are provided. In this embodiment, the root 3 and the head 4 are integrally formed as one shaft.

The root portion 3 is composed of a hollow shaft body 6 and the above-mentioned spiral screw portions 2 and 2 formed so as to project on the outer periphery of the shaft body 6. The shaft body 6 has a central hole 7, and window portions 8 are formed on the left and right side surfaces.

Further, the base portions of the neck portion 5 and the head portion 4 and the root portion 3 each have a tapered portion 9 which gradually expands toward the head portion 4 and the root portion 3 side. Head 4
The cross-sectional shape of is a D-shape having a flat portion 41 on one side surface,
The front and back can be identified.

By doing so, it becomes possible to accurately position the use of the dowel post for technical use in correspondence with the orientation of the flat portion 41 of the head 4 of the artificial tooth root, and significantly improve the efficiency of the technical work. Useful for that.

Originally, the head shape of the artificial tooth root was generally a parallel two-sided cut cylindrical shape, but a parallel two-sided cut conical shape has already been proposed. 2 (a) and 2 (b) show a parallel two-plane cut cylindrical shape, and FIGS. 2 (c) and 2 (d) show a parallel two-plane cut conical shape.

However, in actual use, the head is used for the purpose of maintaining the crown restoration, but the positional relationship with the occlusal plane in the oral cavity is almost always used in an inclined state. To be Therefore, unless the front and back surfaces are distinguishable, the transfer is performed as shown in FIG. 3 in order to prevent the model from being broken and to manufacture a dental technic model for manufacturing an accurate dental restoration. · Dowel of the same shape corresponding to the implant (artificial root) head using Transfer Coping 71
When devising and using the post (Dowel Post) 72, the conventional parallel biplanar implant (artificial root) head form as shown in FIGS. It was revealed that the front and back and front and back could not be distinguished by the Dowel Post.

Front and back / front and back are front and back of the face. When the implant head (head) is cut in parallel with two sides, it is not an angle at right angles to the plane (occlusal plane) that the teeth and implant (artificial root) occlude when functioning as teeth, but usually at an acute angle. As a result of the mating, when taking an impression, when inserting the dowel post into the coping, the tip of the post is small and it is difficult to identify its front-back direction, so it was accidentally rotated 180 degrees. Since it is not possible to identify whether or not it is correct even after it is inserted, it cannot be determined until the stage where the model is released from the impression surface that the direction of the end of the implant head (head) has rotated 180 degrees from the actual direction. There are drawbacks.

On the other hand, since the D-cut head (head) has one plane, there is no possibility of making an error.

Therefore, in the present invention, the form of the head is taken as a cross section D.
The conical shape provided with one flat surface 4a of the cut makes it easy to determine the front and back directionality. The head part of the dowel post has the same shape as the implant head 4.

It has been found that, when six parallel biplanar parts are planted on one side of the jaw, they are unsuitable and impossible to visually form a parallel relationship without mutual undercut.

FIG. 4 shows a two-plane cut head (head) 4 '.
FIG. 8 is a comparative explanatory diagram in the case of a head (head) 4 having one plane D cut.

As shown in FIG. 4, when the implant (artificial root) is implanted inside the jawbone, a wider contact area with the jawbone is acquired, and the directionality that can cope with the load of the occlusal force is taken into consideration. When implanting multiple plants, each is planted in any direction while considering aesthetics and pairing relationships, but at the end of planting the implant head (head) for the purpose of producing a prosthesis. It is necessary to adjust the bending so that they are parallel to each other.

Undercut means that, when the implant (artificial tooth root) is looked down from above, no shadow is formed below the upper part of the head (head). In other words, if you do not aim for a shape that does not leave shadows such as cones or trapezoids, you will not be able to take accurate impressions, and the prosthesis made on the model you made will be like a skirt that does not fit snugly at the lower neck of the model. It becomes a transparent shape, and this makes it unclean even if cemented and it can be detached over time and a good prognosis course cannot be expected (see Fig. 4 (a)).

It is an important condition that the implant heads (heads) 4 such as elongated bamboo shoots are parallel to each other and are not caught in the front, rear, left and right. For the purpose of finishing the shape in such a state, conventionally, the side surface and shaft wall of the implant head (head) are tapered immediately after planting with a high-speed air turbine (600,000 revolutions per minute) to obtain tungsten carbide steel.・ The implant (artificial root) made of titanium material was cut with a bar to correct the form and polished with alumina oxide points.

As a result of this operation, strong vibration is applied to the implant (artificial root) immediately after being planted, and as a result, the implant (artificial root) loosens due to vibration, which adversely affects surrounding bones, which is one of the causes of failure. At the same time, the surroundings are contaminated by the scattering of cutting dust, and the cutting has a high risk of damaging the tongue and oral soft tissue, and at the same time, it takes time and labor costs to cut and polish,
This leads to a drop in labor productivity and is directly linked to a surge in medical costs for implants (artificial roots).

Therefore, since the D-cut flat surface portion 4a is also tapered with respect to the long axis of the implant (artificial tooth root), the implant head (head portion) 4 has a truncated cone shape, so that the undercut is easily performed. Improved so that no parallelism can be acquired mutually (Fig. 4
(See (b)). As a result, implant head
There is no need to cut and adjust the side surface of the, the shape of the standard production head (head) is maintained, and only the length is adjusted.

The length of the head (head) adjusted by cutting is adjusted by copying the length and the shape of the stump on the dowel post using a plastic coping to adjust the tip of the post. This allows the adjusted posts to be used for individual implants (artificial roots) when taking impressions.
It was completed as an Accupost system that can be easily manufactured by inserting the model material into the impression area of and injecting the model material into it.

Nowadays, by using the implant head (head) cutter that the present inventor has already devised, the implant head (head) can be cut to a desired length in an instant. . As a result, cutting with a turbine was not necessary except for adjusting the stump to be slightly flat, and it was useful for shortening the time and improving the rest and healing effect of the implant (artificial root).

Therefore, since a taper (Taper) is given also to the plane portion with respect to the major axis of the implant (artificial root) to make the implant head (head) into a truncated cone shape, the implant (artificial root) is planted. Then, by adjusting the parallel relationship by visual observation for the purpose of acquiring parallelism between adjacent teeth and implants (artificial roots), it became possible to easily acquire parallelism without undercut.

As a result, it is no longer necessary to adjust and polish the side surface of the head (head) for the purpose of eliminating the undercut of the head (head) as in the conventional case, and the head has a length corresponding to the occlusal height. It only needs to be cut properly, and the cutting time and dangerous labor have been extremely reduced.

At the same time, the form of the standard-produced head (head) was kept as it was, and a way was opened where the dowel post produced under the same standard could be applied to accurate and durable model making.

Since the shape of the implant head (head) has conventionally been two parallel surfaces, the undercut Uc is always used.
(Refer to Fig. 4 (a)) and it was necessary to remove the undercut Uc. Therefore, when cutting the side of the head 4 ', cutting vibration by a tungsten carbide bar by a high-speed air turbine and breaking of the bar Dangers such as breakage and scattering of cut pieces, damage to oral soft tissue, and vacuum suction operation required manpower and time.

In addition, the original head shape was a parallel two-plane cut cylindrical shape, which was previously applied to Japanese Patent Application No. 5-2895.
In No. 9, we tried to improve the conical shape so as to eliminate the labor of tapering the side surface of the head after implanting the artificial root, but as a result of changing from the cylindrical shape to the conical shape, the artificial root Immediately after implanting in the bone hole with a dedicated hand key,
There was a phenomenon that it was difficult for the hand key to come off the head.

FIG. 5 shows an example of the hand key.

A "hand key" 50 called a knurling holds an implant head (head) with a simple cylindrical portion 51 and rotationally implants it in a bone hole tapped to a predetermined depth. As a result, the conventional parallel two-sided cut head (head) shape was fine, but as a result of the head (head) changing to a taper shape, contact between the hand key 50 and the head (head) 4 Results in being confined to the slight contact between the thick part of the base of the head 4 and the entrance of the hand key 50, so a strong force works in a narrow range and the implant (artificial root) body The hand key bites into the hand key, and as a result, the hand key does not come off.

Therefore, as shown in FIGS. 1, 2 (e) and 2 (f), one groove 4c for receiving a minus driver bit is provided in the stump 4b of the head 4. As a result, it has become possible to reliably and sufficiently screw into the bone hole. The example shown is configured to accept the bit of a minus driver, but in some cases a plus driver
It can be a driver. However, since the stump is a D-cut monoplanar shape, a minus driver configuration is preferable.

As a result, as a result of the rotary planting operation, the hand
The artificial tooth root part 4 bites into the key 50 and comes into close contact therewith, and the head part 4
I was able to completely avoid the inconvenience that the hand key 50 could not be removed. Therefore, the hand key 50 has been changed from the conventional cylindrical shape to the shape in which the minus driver bit 52 is housed.

As a result of the taper form, the artificial tooth root head can be rotated by the hand key 50 only at the base portion from the neck portion of the head, and the short size hand key cannot reach the base portion, so that it is constantly long.・ As a result, it was obligatory to use a hand key of a size, and there was a case where there was a problem in operation when there were adjacent teeth or a patient whose opening was not large enough.

Therefore, as described above, as a result of inserting one groove 4c for receiving a minus driver in the stump portion of the head 4, the hand key 50 is long-sized, short-sized as required, as before. Both the size and the ease of use have been resolved.

Groove 4c of implant head (head) 4
Makes a cut in the final step of making an implant (artificial root) at the factory.

The screw portion 2 is a double thread screw in this embodiment,
The lead is small and the pitch is small.

The cross-sectional shape of the screw portion 2 is substantially triangular, and the angle α of the screw thread 10 is set in the range of 60 ° to 70 °. Both sloping surfaces of the screw thread 10 are symmetrical, and in this embodiment, they are formed into an equilateral triangle having a vertical direction of approximately 30 °.

FIGS. 7 to 12 show the stress state applied to the inside of the bone 11 around the screw portion 2 when the thread angle α is 56 °, 60 °, 64 °, 70 °, 75 °, 82 °, respectively. It is a thing. In the figure, E1 indicates the Young's modulus of titanium, which is the material of the artificial tooth root, E2 indicates the Young's modulus of the cancellous bone of the bone marrow, and the screw thread angles are shown as the same angle in each figure for comparing the stress states. Incidentally, the Young's modulus E1 of titanium is 10.19 × 10 3 [kgf / cm 2] on average, and the proportional limit is 9.5.
49 × 10 3 [kgf / cm 2], Young's modulus of cancellous bone is 0.2
27 [kgf / cm2], proportional limit 0.1082 × 10 3 [k
gf / cm2]. In the figure, region I is a region where stress is small and safe, region II is a region where stress is moderate and still safe, region I
In II, the stress is large, and sometimes the load is large. Therefore, it is shown that the larger the area of the region I, the smaller the burden on the jawbone, and conversely, the region III.
The larger the area of the, the greater the burden on the jawbone.

When the screw thread angle α is large, the thickness of the screw thread 10 becomes large, so that the rigidity of the screw thread 10 becomes large, and the occlusal force is not buffered in the portion of the screw thread 10 and is applied to the bone tissue,
The stress becomes high locally.

On the other hand, when the thread angle α is small, the thread 10
Since the thickness of the screw thread 10 becomes small, the rigidity of the screw thread 10 becomes small, and even if an occlusal force is applied, the screw thread 10 is elastically deformed and the load acting on the bone tissue is buffered and the stress can be dispersed. However, if the thread angle α is too small, a cushioning effect can be obtained, but the tip of the thread 10 bites into the bone tissue and stress concentration occurs at the tip.

Referring to the drawings, 60 °, 64 °, 70
At °, the range of I (small stress) is relatively wide (Fig. 8, Fig. 9,
10), 75 ° (see FIG. 11), 82 ° (see FIG. 12)
(See), the range of I is narrowed (especially thread 10
Bottom side).

From this data, it can be seen that the stress dispersion effect is high up to 70 °.

On the other hand, at 56 °, the thread 10 and the thread 10
Although the range of I (small stress) between is large, there is a III (large stress) portion near the tip of the thread 10 (see FIG. 2).

With respect to the data of the portion of 56 ° or less, it is clear from the common physical sense that the stress increases.

From these data, approximately 60 ° to 70 °
By setting the range within a certain range, the load such as the occlusal force can be appropriately buffered, and the stress concentration at the screw thread tip portion can be reduced as much as possible, and a uniform stress distribution effect can be obtained.

Further, a normal intraosseous implant (artificial tooth root) is usually implanted inside the bone marrow, but even if the bone tissue around the titanium spiral implant is the cancellous bone of the bone marrow, Even in the case of compact bone, there was no change in the stress distribution map.

Therefore, since the stress inside the jawbone can be evenly dispersed and reduced, it is possible to deal with the case where the amount of residual bone is small or softened bone.

Further, in the artificial tooth root of the present invention, the shaft body 6 is made hollow so as to have a low rigidity, whereby 60 ° to 70 °
Coupled with the setting in the range of °, it is possible to enhance the buffering effect of the load such as the occlusal force, and to reduce the load on the bone tissue as much as possible.

On the other hand, in order to effectively disperse the external force applied to the artificial tooth root 1 and transmit it as a small stress to the surrounding jaw bone, it is advantageous that the screw portion 2 of the artificial tooth root 1 has a large surface area to bear the vertical load. . Here, the length of the threaded portion 2 is determined by the depth of the jawbone 11 to be implanted, and the length of the threaded portion 2 can be increased as much as the pitch p is shorter than in the conventional case.
The contact area increases by the length of the threaded portion 2, and the magnitude of the dispersed stress itself can be reduced.

In this embodiment, the pitch dimension of the screw portion 2 is changed from the conventional 1.76 [mm] to 1.50 [mm]. As a result, an effective area of 1.76 ÷ 1.50 = 1.173 times was obtained. Also, the conventional thread angle is 77 °
That is a special angle, and it has no special mechanical advantage. On the other hand, in the present invention, the general 60
It was found that the stress dispersion effect was improved by 30% or more by setting the angle to be 0, and it was found that the stress dispersion effect was increased by 50% or more as compared with the conventional product due to the synergistic effect with the change of the pitch dimension.

In addition to this, if it is 60 °, a general ISO standard product can be used as a set of three dedicated bone taps, and it depends on a special 77 ° expensive special product that has been used conventionally. The cost can be reduced significantly.

Also, as is well known, the artificial tooth root planting method includes a one-time method and a two-time method. The one-time method involves implanting and implanting an artificial tooth root in the jaw bone by one operation, raising the head, and performing temporary crown restoration there. In the second method, the gingival soft tissue is incised and peeled off in the first operation, an intraosseous implant (artificial root) is embedded in the bone, and the gingival soft tissue is returned and sutured and rested for 3 to 6 months. After waiting for the bone to heal, the second operation is started to start up the embedded implant (artificial root). That is, the soft tissue covering the upper part of the implant (artificial root) is removed, the screw cover of the intraosseous implant (artificial root) is removed, the head is screwed to the intraosseous implant (artificial root), and the head is fixed. It is a method of starting up in two times by connecting.

It is a common physical knowledge that electromotive force is generated when stress is applied to the collagen that constitutes bone, but the current generated by this electromotive force is piezo (Pies).
o) Called current. Piezoelectric current is used in the field of plastic surgery for facilitating healing by treating a fractured limb and other epiphyses by applying a weak current to the fracture line.

A similar phenomenon occurs in the case of the one-time implant (artificial tooth root), and the implant (artificial tooth root) body is subjected to appropriate function recovery immediately after planting, and stress is applied to the implant (artificial tooth root) to obtain the two-time method It has been empirically found that rather than isolating the implant (artificial root) from external force and blocking the external force transmission to the surrounding bone, applying appropriate stress promotes rapid functional healing of bone tissue. I know. Please refer to P. of the attached document “Shell Shev Implant Clinical”. Photograph 2 of case 2 of P.4, P. Photograph of case 4 of Case 3, P. 5 Photograph 7 of case 5 of P. 7, P. Photo 7 and P.8. It is clear from the comparison of Photo 14 of 9 above. For that purpose, the stress dispersion effect on the bone tissue around the implant (artificial root) body is a particularly important factor. It can be said that it can be compared with "rigid structure" and "soft structure" in architectural engineering.

Stress distribution on bone made of Collagen has important consequences on the consequences of the piezocurrent effect, which promotes healing of bone trauma.

Other implants of today (artificial roots)
The body is in contradiction to the "topological theory" and does not apply the mechanical significance of "rigid structure" and "flexible structure" and the Piezo current effect.

There is no exception for other implants (artificial roots) that have a "rigid structure" and do not know the "top theory", and the cortical bone present in the surface of the jawbone with a thickness of 1 to 2 [mm] in the one-time method. Stress is required to maintain and fix the compact bone at the initial stage of planting. As a result, without exception, bone resorption occurs around the neck of the implant (artificial root), and inflammation of the soft tissue also occurs in that area, which is one of the causes of trouble and failure.

On the other hand, both the spiral implant and the syncrest implant have morphological characteristics based on the "top basic theory", and the neck has a diameter of 2.0 mm, while the bone drill has a compact bone. The hole size in the hole is 2.4
[Mm], the diameter of the tap is 4.0 [mm],
There is a peculiar morphological feature that does not require maintenance or stress burden on the compact bone at all from the initial stage of planting, and requires stress burden and maintenance only on the cancellous bone of bone marrow.

As a result, since it is possible to perform single implantation and immediate temporary crown restoration, it is not necessary to scrape and cover the adjacent teeth on both sides, which is a general common knowledge of implants (artificial roots), and to fix them together. Moreover, as a result of avoiding the sacrifice of both adjacent teeth, safe, quick and inexpensive treatment is possible.

Its characteristics are: a. Large threads, b. Hollow structure, c. The pitch is large, d. Open the window to increase the elasticity of the mountain portion accordingly, e. The crystal grains of titanium material are processed in consideration of elastic modulus. That is, the size of the crystal grains is adjusted so that the elastic modulus of titanium approaches the elastic modulus of cancellous bone.

For the above reasons, this implant (artificial tooth root) has achieved epoch-making clinical results even though it is a one-time method, and has been repeatedly given "origami" by professional academic societies.

As in the present invention, by setting the screw thread angle (approximately 60 ° to 70 °) effective for stress dispersion, the stress dispersion effect is further improved by 50% or more. This is an epoch-making thing when planting artificial tooth roots. Most conventional artificial tooth roots remain rested without any load for 3 to 6 months after the planting, and they can be restored to their function immediately after the planting, because they spend a restless period as the initial healing period. The improvement of the initial stress dispersion effect is an essential condition for expanding the range of indications and achieving safe and reliable healing.

As described above, when the shaft body 6 of the screw portion 2 is hollow, the stress dispersion effect is enhanced, but problems occur in strength and durability.

In this respect, the outer diameter of the screw thread is φ4.0 [mm].
When the root diameter (shaft diameter) is 2.4 [mm] and the hole diameter of the central hole 7 is φ1.6 [mm], the strength and durability are excellent while maintaining the stress dispersion effect. It was possible to provide an artificial tooth root.

This hole diameter is 0.3 [m] when it is changed from 1.8 [mm] in the past to 1.6 [mm].
Only by changing the thickness of m] to 0.4 [mm], the mechanical strength against bending stress could be enhanced by more than 50% at the maximum. In this embodiment, the height H of the thread 10 is 0.8 [mm], the width a of the thread crest is 0.2 [mm],
The width b of the valley is set to 0.5 [mm].

The height H of the screw thread 10 is important for securing a contact area for the stress dispersion. If it is too low, the dispersion effect is reduced, and if it is too high, the outer diameter becomes thick and the artificial tooth root itself becomes thick. In addition, it is unsuitable because it requires an excessive torque to cut the tap, and when it is planted in a thin jawbone, there is a drawback that the indications are limited. Therefore, 0.8 to 2.3 [m
m] is suitable, and since the width b of the valley defines the thickness of the portion to be loaded, if the width b is too small, the strength becomes weak, and if it is too large, the pitch becomes large and the surface area decreases. Therefore, about 0.4 to 0.7 [mm] is preferable.

Further, the thread crest a is a portion which bites into the bone, and when the width a is small, the stress concentration becomes large when the width a becomes small and sharp, so about 0.15 to 0.4 [mm] is preferable.

In FIG. 13, 0 ° and 45 ° with respect to the window 8 direction.
The bending test results of the artificial roots of the conventional example and the present example when loads are applied from three directions of 90 ° and 90 ° are shown.
As is apparent from FIG. 13, it can be seen that the strength is 50% higher than that of the conventional example with respect to the load from the direction of 90 ° with respect to the window direction.

FIG. 14 shows the compression test result. It is shown that the artificial tooth root of the present invention has higher mechanical strength than the conventional example against this compressive load.

Utility model registration first proposed by the present inventor
In the artificial tooth root commercialized in 9624219, as a result of standardizing a certain relationship between the head (head) and the spiral joint, the spiral joint can be confirmed when the direction of the head (head) is seen. If the window of the spiral is always positioned in the direction of the bone marrow when implanted in thin bone, there is no risk of connective tissue invading the hollow part of the spiral and inhibiting regeneration of bone tissue. Since it has been found that regeneration of bone tissue occurs, conventionally, it has been a general rule to apply an artificial tooth root having a diameter of 4 [mm] to a site having a bone width of 6 [mm] or more. It has been confirmed that it is possible to sufficiently cope with a thin site of about [mm], and it has been possible to significantly expand the indications.

Here, a method and concept of implanting an artificial tooth root having a diameter of 4.0 [mm] in the bone width of 3.0 [mm] will be described with reference to FIG. The illustrated example has a width of 3 [mm]
The threaded portion having a diameter of 4 [mm] is applied to the bone. That is, diameter 4.0 [mm], bone width 3.0 [m
m], the hole diameter d of the central hole 7 is 1.6 [mm] and the wall thickness t is 0.4 [mm]. In this case, the window 8,
It is important that 8 goes into the bone.

The right half of the figure is a cross-sectional view of the alveolar bone 11 having a width of 3.0 [mm]. About 1 [mm] of the surface layer is the dense bone 12 and the bone marrow tissue of the soft cancellous bone 13 inside. is there. The left half of the drawing is a cross-sectional view of a spiral, and it is important that the two-walled portions connected in the axial direction are located outside the compact bone 12. That is, if the window portion communicates with the outside, the soft tissue enters and inhibits bone formation.

First, as a procedure for implanting an artificial tooth root, a guide hole is excavated in the central portion with a thin drill having a diameter of 1.2 [mm], and the diameter is gradually increased to 1.5 [mm], 1.8.
Enlarge with a [mm], 2.4 [mm] drill, then tap with a diameter of 3.0 [mm], which is the same as the bone width, and 4.0 [mm], which is thicker than the bone width. It is relatively easy to hold the center line by supporting the hard compact bone in the surface layer, and it is possible to form the tap hole of 4.0 [mm] in the bone width portion of 3.0 [mm]. Since the D-cut flat portion 41 of the head portion 4 of the artificial tooth root 1 and the shaft body 6 that becomes the support of the root portion 3 are on the same axial surface, the direction of the window portion can be clearly determined from the outside, so that the external force is not affected. It can be planted safely, taking into consideration the direction in which it can respond dynamically and effectively.

The material of the artificial tooth root is not limited to titanium, and various materials having a predetermined strength, biocompatibility, etc. can be used.

The shape of the thread is not limited to the triangular thread as shown in the figure, but various shapes such as trapezoidal shape and corrugated shape can be selected.

The screw portion 2 is a double thread screw in this embodiment,
The lead is small and the pitch is small. However, the number of threads of the threaded portion 2 is not limited to two and may be one or three or more.

FIG. 16 shows a single-thread screw type artificial tooth root.

16 (a) to 16 (c) are exactly the same as the two-thread type embodiment described above except that the screw portion 201 is a one-thread screw, and therefore the same reference numerals are used for the same components. Is omitted and its description is omitted.

16 (d) to 16 (f) is a solid sinkrest type, the head 4 and neck 9 are exactly the same, and the neck 9 is made of cortical bone at the initial stage of planting. The external force is supported only by the screw portion 202 embedded in the soft cancellous bone without interfering with the compact bone, and the same components are designated by the same reference numerals. The shape of the sink rest type screw portion 202 is a taper shape that gradually tapers toward the lower end, and the screw thread 210 is formed in a spiral line at a predetermined pitch. The thread diameter of the thread 210 is gradually reduced so as to be tapered.

In the case of this syncrest type, it is preferable to set the thread angle β to about 90 ° to 120 °.

Considering the mechanical dispersion effect, the lead angle of one article is half that of two articles, so the slip on the side surface of the thread corresponding to "top" is reduced, About 20% better than Article 2.

Conventionally, a tap was cut on a bone by hand to form a groove for an artificial tooth root, but this work requires a great deal of attention and force, and it is difficult to prevent the destruction of the bone groove due to hand shake. , Required time and skillful effort. Since it is necessary to rotate the 1-row type twice as much as the 2-row type to form the tap, the 2-row type is generally used because it requires less labor.

However, the present inventor has already experienced that a motor having a strong torque has been developed due to technological innovation in recent years and that the tap can be formed electrically. As a result, there is no need for any troublesome tap formation by hand, and moreover, a sharp bone groove without shaking can be formed within a short time of about one-tenth, and one row rotates twice as much as two rows. It turns out that the need for tapping does not cause any problems with the motor.

Further, the sharpness of the tap is improved so that the tap can be easily formed even on a hard bone, or an implant (artificial root)
There is a limit in the two-row type in order to perform a smooth tap operation when the comrades come close to each other and the taps collide with each other.

That is, conventionally, in the case where the bone has a sufficient depth, the upper 2/3 is soft, and the lower 1/3 is markedly hard. Drilling was possible, but tap formation was not possible at all.

The reason is that when the tap is cut into the hard portion, the tap portion of the upper soft portion is crushed and destroyed.

In the conventional double thread screw, the notch groove 2 of the tap is used.
The structure of 3 is tap 2 as shown in FIGS.
Parallel to the long axis 21 of 0, as a result, the crests 22 of the three crest structure serving as the cutting edge of the tap 20 are arranged in three rows in the long axis direction, and when the tap 20 is rotated to perform cutting, As a result of the blades 22a of the three rows of ridges 22 synchronously biting into the surroundings at the same time, inside the jawbone where the hardness of the bone around the tap 20 differs depending on the direction, within the three rows at a time in the hard direction Since one row tries to bite, an excessively large torque is required temporarily, and in addition, it is extremely difficult to form a smooth tap due to the reaction to swing the shaft in a region where the bone quality has a difference in hardness.

Since the jawbone is narrow and there is not enough space for planting the artificial tooth root, it is necessary for the artificial tooth roots to approach each other and sometimes contact each other. In the tap 20 of the screw, the blade 2 of the tap 20
Since 2a is arranged on the same axial surface, there is a drawback that smooth penetration cutting cannot be performed for the same reason.

With the double thread, the notch groove 23 of the tap 20 is used.
Providing a receding lead angle to the groove makes the angle of the tip of the cutting blade 22a too sharp, resulting in breakage of the cutting edge, which is not expected to be practical.

As a solution to this problem, it was historically common practice to cut the tap with a hand, but even with a single-thread screw, a sharp tap with less than 1/10 the time with an electric motor and without shaking Since it was found that it would break, it was found to be more appropriate to use a single-thread screw.

FIG. 17 shows the case where the artificial tooth root is a single thread screw.
As shown in (a) to (c), it becomes possible to provide the tap 30 with a groove 33 having a large receding lead angle, and as a result, the crest portion 32 serving as the blade 32a of the tap 30 is different from the conventional one. As a result of being arranged in a spiral shape instead of being arranged in parallel to the long axis 31, the cutting edge portions of the taps 30 are continuously in contact with the cutting surface at different time points, and as a result, smoothly ¼ the conventional one without disturbing the axial property. It turns out that the tap can be cut with a small torque. Tap 30 by changing from Article 2 to Article 1
The lead angle is doubled, and even if the tap 30 has the same receding lead angle, the blade tip is twice as thick and tough as the case where the receding lead angle is given to the double thread.

As a result, even when the tap 30 comes into contact with the artificial tooth root that was previously implanted, no runout occurs, and smooth tap formation is possible. As shown in FIG. Enables dense planting. In the figure, A is the soft tissue surface and B is the bone tissue surface.

It is similar to the fact that the two-cylinder engine is easy to knock, but the sixteen-cylinder engine can obtain smooth rotation without knocking.

As a result, the torque of the electric motor can be reduced to 1/4 of that of the conventional one, which also directly affects the structure of the handpiece that transmits the torque, which is directly related to cost reduction and improvement of durability. At the same time, it is directly linked to the safety and ease of surgical operation.

As a result, the operation of the artificial dental root can be performed by the motor incorporated in the conventional dental unit.
That is, an expensive motor that costs 400,000 to 600,000 yen, and sometimes 1.5 million yen is no longer necessary.

The Applicant previously found that the incision, peeling, and suturing of the gingival periosteum peculiar to implant (artificial root) surgery are harmful.
It proves to be useless and unnecessary, and the device for cooling water injection is expensive, and it is difficult and painful for both the patient and the operator to inject water. Since the operator and the patient are forced to maintain a certain posture, free operation is limited, and the operating field is hampered by water injection, making it difficult to clearly see the local area and the depth of the drill details. Since it is extremely difficult to confirm the above, there is a drawback that it is likely to be accompanied by a risk of damaging the inferior alveolar artery or nerve.

Further, since the physiological saline is applied to the mucous membrane of the throat near the patient's soft palate and it is dried by suction, the patient feels salty and painful, coughs, and the unexpected sway causes the drill to break. There is a danger of easily causing saliva contamination of the folding and taps.

These dangers and difficulties have been eliminated as a result of eliminating the need for water injection cooling operation. In addition, an assistant is not necessary in many cases, although it is necessary depending on the site, and it is now possible for an operator to implant alone (artificial root).

Since the osmotic pressure of physiological saline is not equal to the osmotic pressure of tissue, cells on the surface of the tissue are damaged by the injection cooling operation using physiological saline and lose the ability to regenerate and heal, resulting in delayed healing and postoperative surgery. Research reports have published that there is no benefit other than causing pain. In addition, since all of today's water cooling systems do not have a mechanism for exchanging the water transfer tube with a fresh sterilized tube every time, in the clinical field where it is used occasionally, the inside of the tube is contaminated and becomes a source of infection. There is. As an alternative method, a method using a high torque, low speed rotation motor is proposed.

The soaring medical cost is a big problem that cannot be ignored for both patients and operators.

Reducing the price of implant (artificial root) tools is an important condition for promoting the spread and implementation of implants (artificial root).

By adopting the single-thread type as shown in FIG. 16, the shape becomes closer to the "top basic theory", and the lead angle of the screw becomes 1/2, so that the sliding stress is reduced.

FIG. 18 shows a tool set.

In the case of electric drive, as shown in the drawing, the drill 60
If the part can be used, tap 6 of the same length
1 can be used, and the implant holder 62 that can hold the same length as the implant body (artificial root) 63 also uses the motor drive hand piece 64 to smooth the planting operation in 1/10 the time of manual work without shaking. Can be completed in

FIG. 19 shows the shape of the tip of the tap.

As shown in FIG. 19, since the shape of the groove 33 'of the conventional bone tap is the V shape in the related art, the bone cutting piece is clogged, cutting resistance increases and at the same time the bite stops and the operation is stopped. Since it took a lot of time and labor to remove the clogging of the cutting piece after the interruption, the V-shape was improved to the U-shape, and the straight groove 33 'was changed to the spiral groove 33.
As a result, the clogging of the groove was eliminated and continuous tap cutting became possible. As a result, the operation was not interrupted and the speed was improved 10 times or more. At the same time, it was possible to prevent tap contamination.

It has been found that a single-thread screw makes it possible to form the start portion of the tooth tip of the tap 30 with a groove having a lead angle that is moderately sharp and recedes to a moderately sturdy angle. . As a result, it has become possible to effectively cut even hard bone that has not had teeth in the past, as a result of changing the shape of the cutting edge.

As shown in FIG. 19E, the tap groove 33 is formed.
The one with a straight ′ cuts the cutting surface at 90 degrees, while the one with a spiral cuts at an acute angle when the edge of the tip is viewed from the side, as shown in FIG. Cut the surface. In FIG. 6 (f), the angle γ is a rake angle for improving the bite, and the angle δ is a clearance angle for reducing the cutting resistance to prevent heat generation.

As a result, there has been opened up a way to utilize a significantly hard bone tissue which could not be effectively utilized in the past. As a result, it has become possible to further expand the indications.

[0153]

EFFECTS OF THE INVENTION The present invention has the above-described structure and operation. Since the angle of the screw thread of the screw portion is set in the range of 60 ° to 70 °, the occlusal force is most efficiently and evenly applied to the jawbone. It can be dispersed and the burden on the jaw bone can be reduced. Therefore, many areas and patients that have been excluded from the indications for implants (artificial roots) due to the fact that the amount of residual bone is small or the bone quality is soft due to osteoporosis in old people, etc. may be applied with artificial roots. it can.

Further, the failure immediately after planting can be largely solved by the large increase in the stress dispersion effect at the initial stage.

[Brief description of drawings]

FIG. 1 shows an artificial tooth root according to an embodiment of the present invention, in which FIG. 1 (a) is a front view, FIG. 1 (b) is a plan view, and FIG.
(c) is a partially omitted broken perspective view, and (d) is an enlarged view of a screw thread portion.

FIG. 2 is a diagram showing a head shape of an artificial dental root having a parallel-two-plane cut cylindrical shape, a parallel-two-plane cut cone shape, and a one-plane D cut cone shape.

FIG. 3 is a diagram showing a coping and a dowel post.

FIG. 4 is an explanatory diagram for comparing a parallel two-sided cut head (head) with a one-plane tapered cut head (head).

FIG. 5 is a diagram showing a hand key.

FIG. 6 is a diagram showing a configuration example in which a groove for driver engagement is formed in an artificial tooth root head.

FIG. 7 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 56 °.

FIG. 8 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 60 °.

FIG. 9 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 64 °.

FIG. 10 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 70 °.

FIG. 11 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 75 °.

FIG. 12 is a diagram showing a stress state in the vicinity of a thread portion when the thread angle is 82 °.

FIG. 13 (a) is a graph showing bending test results of the present invention and a conventional artificial tooth root, and FIG. 13 (b) is a diagram showing a load acting direction of the bending test.

FIG. 14 is a graph showing compression test results of the present invention and a conventional artificial tooth root.

FIG. 15 is an explanatory diagram for implanting an artificial dental root having a diameter larger than the bone width of the present invention.

16 (a) to 16 (f) are views showing a single-row type artificial tooth root.

FIG. 17 is a diagram showing a configuration example of a tap.

FIG. 18 is a view showing a tool set used for planting an artificial tooth root of the present invention.

FIG. 19 is a diagram showing a shape of a tip of a tap.

FIG. 20 is a diagram showing a state in which artificial tooth roots are densely planted.

[Explanation of symbols]

 1 Artificial tooth root (implant) 2 Screw part 3 Root part 4 Head part (head) 5 Neck part (neck) 6 Shaft body 7 Central hole 8 Window part 10 Screw thread 11 Bone α Screw thread angle

Claims (8)

[Claims] 1. An artificial dental root provided with a screw portion to be implanted in a jaw bone, wherein an angle of a thread of the screw portion is set in a range of about 60 ° to 70 °. 2. The artificial tooth root according to claim 1, wherein the threaded portion is formed around a hollow shaft body having a central hole. 3. The artificial tooth root according to claim 2, wherein the shaft body is provided with a window portion communicating with the central hole. 4. The neck portion connecting the screw portion to the head is made thinner than the outer diameter of the screw portion so that the cortical bone at the initial stage of implantation,
The artificial tooth root according to claim 1, 2, or 3, wherein the artificial tooth root is set to a size that does not come into contact with the compact bone, and the load is dispersed and applied to the cancellous bone of the bone marrow in which the screw portion is embedded. 5. The artificial tooth root according to claim 4, wherein the thickness of the neck portion is set in a range up to about 2 [mm]. 6. The artificial tooth root according to claim 1, 2, 3, 4, or 5, wherein the head has a modified cross-sectional shape that narrows toward the tip so that orientation can be identified and rotational implantation can be performed. 7. The artificial tooth root according to claim 6, wherein the head has a conical shape with one plane having a D-cut cross section. 8. The structure according to claim 6, wherein the stump of the head has a groove for receiving a bit of a driver.
The artificial tooth root described in.