JP2014180366A - Screw implant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a product that can be firmly fixed in a bone such as an alveolar bone without loosening, and enables the planting and removal to be performed precisely and easily, in a screw implant that can be used for orthodontics and surgery medical purpose, etc.SOLUTION: An area of a following side flank surface forming a screw thread is widened by one time to two times more than the area of an advancing side flank surface, and a taper angle in a taper shape with a screw front side tapered is 0.5°-5.0°. Also, the widening of the area of the following side flank more than the area of the advancing side flank is set by a flank angle and a screw depth of a thread, in which the advancing side flank angle is 5°-20° and the following side flank angle is 20°-40°, and a height of the screw thread is 10-25% less than the outer diameter of the screw thread in the immediate vicinity of the head.

Description

  The present invention relates to a screw implant that can be used for fixing orthodontic or dental prosthetic implants.

  In recent years, screw implants for orthodontic use and dental prosthesis have been rapidly used. This screw implant is screw-like, embedded in the alveolar bone that supports the tooth from the top of the gum (screwed), and forcibly moving the tooth to a normal position by an orthodontic member such as a wire, It is used as a fixing source of the correction member.

  For example, in Patent Document 1, a head is formed in the upper part, and a fixed part for fixing an elastic member, a tool fixing part for connecting a tool, and a planting part planted in the alveolar bone in the lower part thereof , An implant having a predetermined length of screws, each of which has an upper, lower, and narrow conical shape, and one or two upper layers of the conical screw threads. A screw implant is disclosed in which a surface having a predetermined width is formed at the tip of the above thread, and an acute angle is formed at the bottom of the thread.

  Patent Document 2 discloses an orthodontic implant anchor for fixing a biasing member for correcting the position of a tooth by applying a moving force to the tooth. A first fitting portion, an intermediate portion, a second fitting portion, and a head portion, and the two fitting portions each have an outer diameter at a distal end portion and an outer diameter at a distal end portion. The intermediate portion is a truncated cone shape defined by a distal end side cross section of the first fitting portion and a distal end side cross section of the second fitting portion. An orthodontic implant anchor configured within a space is disclosed.

JP-T-2006-514840 JP2011-135910A

  Screw implants used for orthodontics are used as a fixed source for orthodontic members (wires, etc.) when correcting dentition. It is necessary that the embedded screw implant does not come loose from the alveolar bone and does not come out of the alveolar bone and is firmly fixed. Moreover, since it is necessary to provide in narrow places, such as between teeth, it is necessary to be accurately and easily embedded in a stable posture. Furthermore, it is necessary that the screw implant can be easily removed after orthodontic correction is completed.

  However, the conventional orthodontic screw implant as described in Patent Document 1 has a problem that it breaks or falls during long-term orthodontic treatment such as treatment for 2 years, or due to the effects of repeated vibration. Reported that loosening occurred during treatment and orthodontic appliances could not fix the teeth to be treated firmly, and that the rate was as high as 23.2% of implanted orthodontic screw implants There is also.

  If the screw implant falls off, the dentition cannot be accurately corrected. In addition, when the screw implant breaks, an operation for removing fragments remaining in the alveolar bone is necessary, and since the operation is extremely difficult, the alveolar bone is easily damaged. A problem occurs.

  Therefore, the invention described in Patent Document 2 has been disclosed. However, since the invention described in Patent Document 2 is embedded in a substantially horizontal direction that is substantially perpendicular to the tooth meshing direction, the tooth meshing. When the vibration in the same direction as that of the direction is repeatedly received, there is a concern that the screw part is likely to loosen or come off when it must be attached in the vertical direction because the length of the screw part is short.

  The present invention was devised in view of these problems, and in a screw implant that can be used for orthodontic use etc., it can be firmly fixed over a long period of time without loosening to bones such as alveolar bone. Alternatively, it is an object to provide a screw implant that can be easily removed.

  The screw implant 1 according to claim 1 is a screw-type screw implant 1 used for orthodontic use or dental prosthesis, and advances the area of the follow-up flank surface F1 that forms the thread 2a. The taper angle θ of the taper shape in which the screw tip side is tapered is set to 0.5 ° to 5.0 °.

  The area W of the flank surface of each screw thread 2a is obtained by Equation 1. In Equation 1, d1 is the outer diameter, d2 is the diameter of the bottom of the valley, and h is a value obtained by multiplying the height H of the thread by tan (flank angle (following flank angle α or leading flank angle β)). To do.

  From [Equation 1] and [Equation 2], the area W of the flank surface of the thread 2a is d1 indicating the outer diameter, d2 indicating the diameter of the bottom of the valley, the height H of the thread, the flank flank angle α or It can be seen that it is determined by the advance side flank angle β.

  The taper angle θ refers to an angle formed by the center line (vertical line) L of the screw body 2 and the inclined line S along the outer peripheral surface of the screw body 2.

  The screw implant 1 according to claim 2 is the screw implant 1 according to claim 1, wherein the advance side flank angle β of the screw thread 2a is set to 5 ° to 20 ° and the follower side flank angle α is set to 20 ° to 40 °. The height H of the thread 2a is less than 10 to 25% of the outer diameter of the thread 2a closest to the head 3, and the area of the follower flank surface F1 is made larger than the area of the advance flank surface F2. And

  The screw implant 1 according to claim 1 is configured such that the area of the contact surface with the alveolar bone in the screw advance direction is smaller than the area of the contact surface with the alveolar bone in the screw removal direction (that is, in the screw removal direction). The contact area with the alveolar bone (following flank surface F1) is made larger than the contact area with the alveolar bone (advancing flank surface F2) in the advancing direction of the screw, and a taper is provided with a taper on the screw tip side. From the alveolar bone, even if there is repeated vibration due to jaw movement during long-term orthodontic treatment, even if it receives repeated tensile load by a tooth corrector etc. or a gap between the jaw and screw screw part due to bone resorption occurs Since it is difficult to come off and a gap is hardly formed on the contact surface with the alveolar bone, it has an effect of being difficult to loosen, and can be fixed while being embedded in the alveolar bone for a long period of several years.

  That is, since the screw body 2 of the screw implant 1 is formed in a tapered shape, the flank surface of the screw thread 2a of the screw body 2 embedded in a small hole previously drilled is always over the entire length. This is because it makes strong contact with the alveolar bone. That is, a so-called screw path formed by the tip portion of the screw body 2 is embedded so that the subsequent thread 2a having a larger diameter gradually expands, and a flank surface that is an outer peripheral surface of the thread 2a. This is because the whole of this becomes a state of pressing the alveolar bone.

  Incidentally, when the screw body 2 is formed in a straight shape, the portion excluding the tip portion is embedded without expanding the screw path formed by the tip portion, and thus does not make strong contact with the alveolar bone. Therefore, the assembly force with respect to the alveolar bone becomes weaker than that of the tapered screw implant 1 according to the present invention.

  Moreover, by setting the taper angle θ of the screw body 2 in the range of 0.5 ° to 5.0 °, the screw body 2 can be firmly fixed to the alveolar bone. That is, when the taper angle θ is set to 0.5 ° or less, the difference from the conventional screw implant in which the screw body 2 is straight is small, and conversely, when the taper angle θ is set to 5.0 ° or more, the alveolar bone is not affected. This is because embedding becomes difficult.

  Furthermore, the area of the advance side flank surface F2 forming the thread 2a is made smaller than the area of the follower side flank surface F1. Since the flank surface, which is the outer surface from the top of the thread 2a to the bottom of the valley, is a surface that directly contacts the alveolar bone when embedded, the thread surface 2a and the alveoli have a larger area of the flank surface. The contact resistance with the bone increases, and the pressing force of the flank surface of the thread 2a against the alveolar bone increases.

  Since the screw body 2 of the screw implant 1 according to the present invention is a taper screw with the screw tip side tapered, it is formed when the screw implant 1 is screwed into the alveolar bone with respect to an external force that moves the screw implant 1 in the advance direction. Since the formed hole is smaller as it goes to the advance side, and the screw thread 2a is larger from the screw tip side to the head side, the flank surface F2 on the advance side of the screw thread 2a strongly interferes with the surface of the alveolar bone. Thereby, since the screw implant 1 does not move with respect to the external force which is going to move the screw implant 1 to the advancing direction side, there exists an effect that it is hard to produce looseness.

  However, with respect to the external force that tries to move the screw implant 1 to the head side, the hole formed when screwing into the alveolar bone is larger toward the head side, and the screw thread 2a is from the head side to the screw tip side. Since it is so small, the follower flank surface F1 of the screw thread 2a has a weak interference with the surface of the alveolar bone. As a result, there is a problem that the screw implant 1 is easy to move against an external force that tries to move the screw implant 1 to the head side. Therefore, there is a problem that the screw implant 1 tends to be loosened. However, the follower flank surface F1 that forms the thread 2a. Since the contact resistance between the thread 2a and the alveolar bone is increased and the pressing force of the flank surface of the thread 2a against the alveolar bone is increased, the screw implant 1 is placed on the head side. Since the screw implant 1 does not move with respect to an external force to be moved, there is an effect that the loosening hardly occurs.

  Moreover, by having set it as said structure, embedding or removal of the said screw implant 1 can be performed easily. That is, in the screw implant 1, the outer peripheral surface of the taper body 2 formed in a tapered shape has a little screw path already formed in the alveolar bone from the front end portion toward the rear end portion as described above. This is because it is embedded while being in contact with each other so as to expand.

  Further, when the screw implant 1 is removed, the screw path formed in a tapered shape by the screw body 2 is pulled out while rotating in the opposite direction, so that the portion other than the upper end is brought into contact with the alveolar bone as it is pulled out. The power gradually weakens. Therefore, it can be removed very easily.

  The screw implant 1 according to claim 2 has the same effect as that of the invention according to claim 1, and can make it difficult to remove the screw plant 1 from the alveolar bone.

1 is a schematic front view showing a screw implant according to the present invention. It is an expanded sectional view of the thread part of the screw implant shown in FIG. It is a general | schematic front view which shows the other shape of the head of the screw implant which concerns on this invention. It is explanatory drawing which shows the state which embedded the screw implant of this invention in the alveolar bone.

  As shown in FIG. 1, the screw implant 1 according to the present invention is a screw-type screw implant 1 used for orthodontic use or dental prosthesis, and has an area of a follower flank surface F1 forming a screw thread 2a. The taper angle θ of a taper shape with a taper side tapered to be more than 1 to 2 times wider than the area of the advance side flank surface F2 is set to 0.5 ° to 5.0 °.

  The screw implant 1 includes a screw body 2, a head 3, and a connecting portion 4 provided therebetween, and the material is made of stainless steel, titanium, or the like. The total length for orthodontic and dental prosthesis is generally about 5 to 20 mm. Then, as shown in FIG. 4, in the vicinity of the tooth T, it is embedded in the alveolar bone from above the gum C and becomes a fixing source of the correction member M such as a wire for correcting the dentition.

  As shown in FIG. 1, the head 3 has a planar circular top 3 b formed at the upper end thereof, a planar regular hexagonal operation portion 3 c provided below it, a top 3 b and an operation portion 3 c. There is a form composed of the fastening part 3a formed between the two parts, or a form in which a hole is provided in the fastening part 3a formed in the head part 3 as shown in FIG. Both the planar regular hexagonal form and the form provided with the hole are used when correcting the dentition.

  The continuous portion 4 is formed in a columnar straight shape, the outer diameter thereof is set to the same outer diameter as the top diameter of the thread 2a of the screw body 2, and the length of the continuous portion 4 is the screw implant 1. Is set to such a length that the gingiva is not caught in the screw body 2 of the screw implant 1 when the insertion is completed.

  Next, the screw body 2 will be described. The screw body 2 is a male screw, and is composed of a shaft portion and a screw portion. The shaft of the present invention has a tapered shape. And the taper shape of this invention makes taper angle (theta) of the taper shape which tapered the screw tip side into 0.5 degrees-5.0 degrees.

  The screw main body 2 which is a feature of the shape of the shaft portion of the screw main body 2 can be made difficult to loosen by having a tapered shape. That is, a so-called screw path formed by the tip portion of the screw body 2 is embedded so that the subsequent thread having a larger diameter gradually expands, and the entire flank surface that is the outer peripheral surface of the thread is This is because the alveolar bone is pressed, and the flank surfaces (advance side flank surface F2 and follower side flank surface F1) always come into strong contact with the alveolar bone throughout its entire length.

  In addition, since the screw body 2 is formed in a tapered shape, the contact resistance at the time of embedding can be reduced, and screwing can be performed more easily.

  Furthermore, when the screw body 2 is formed in a tapered shape, the contact resistance between the outer peripheral surface of the screw body 2 and the alveolar bone can be gradually reduced when the screw body 2 is pulled out. Thereby, removal from an alveolar bone can also be performed easily.

  Next, as shown in FIG. 2, the form of the screw portion will be described. The form of the thread portion can be generally defined by the pitch P, the outer diameter, the diameter of the valley, and the angle of the thread 2a. One half of the difference between the outer diameter and the valley diameter is called the thread height H, and the angle of the thread 2a is defined by the sum of the follower flank angle α and the advance flank angle β. The slope contacting the alveolar bone in the screw removal direction is represented as a follower flank surface F1, and the slope contacting the alveolar bone in the screw traveling direction is represented as an advancing flank surface F2.

The area of the flank flank F1 or the lead flank F2 of the flank face of the thread 2a depends on the outer diameter, the bottom diameter of the valley, the height H of the thread, the flank flank angle α or the lead flank angle β. It is determined. Therefore, it is possible to compare the area of the flank flank F1 and the advance flank F2 of the flank according to the size of the elements, and the respective areas can be obtained.

  In the screw implant 1 of the present invention, the area of the follow-up flank surface F1 is set to be more than 1 to 2 times wider than the area of the advance-side flank surface F2, and the advance flank angle of the screw thread is 5 ° to 20 °. The follower flank angle is set to 20 ° to 40 °, and the height of each thread 2a of the taper screw is set to less than 10 to 25% of the outer diameter of the thread 2a closest to the head 3.

  Screw type screw implants used for orthodontic and dental prostheses generally have a contact area on the moving direction side (advance side) of the screw (flank surface area) and a contact area on the removal direction side (following side) ( The area of the follower flank surface F1 of the present invention is set to be more than 1 times the area of the advance side flank surface F2 in consideration of ease of screwing. The area of the follower flank surface F1 is set to be twice or less than the area of the advance flank surface F2.

  If the advance flank angle of the screw thread is less than 5 °, it is difficult to screw in, and if it exceeds 20 °, the screw thread angle becomes too large, so that screwing is difficult.

  When the height of each thread of the taper screw is less than 10% of the outer diameter of the thread closest to the head, the contact area (flank surface area) becomes smaller, so the tightening force, tightening torque or loosening torque When the height of each thread of the taper screw is 25% or more of the outer diameter of the thread closest to the head, the diameter of the shaft portion of the screw body 2, that is, the diameter of the valley becomes too small. This is because the screw body 2 is easily broken.

  As a feature of the form of the screw portion, the contact area with the alveolar bone in the screw removal direction (following flank surface F1) is made larger than the contact area with the alveolar bone in the screw advance direction (advance side flank surface F2). Therefore, repeated vibration due to jaw movement during long-term orthodontic treatment occurs, and even if a repeated tensile load is applied by a tooth correction tool, etc., or a gap between the jaw and screw screw part due to bone resorption occurs, It is hard to come off, and it is hard to loosen because there is no gap on the contact surface with the alveolar bone. Thereby, it can be fixed while being embedded in the alveolar bone for a long period of several years.

  In order to confirm the performance of the screw implant 1 according to the present invention, first, the contact angle between the screw thread on the advancing direction side and the alveolar bone is made with the same taper angle, and the contact between the screw thread on the direction side and the alveolar bone In the case of a form smaller than the area, secondly, the contact area between the screw thread on the advancing direction side and the alveolar bone is made smaller than the contact area between the screw thread on the pulling direction side and the alveolar bone, and the contact area ratio is made the same and tapered. A comparison between the cornered and straight configurations was tested.

  The first test will be described. For the screw implants used for the test, the taper angle is 1 °, the pitch is 0.5, the outer diameter of the screw body closest to the head is 1.4 mm, and the thread height is 0.2 mm. As a different setting, the advance flank angle and the follower flank angle of the screw implant to be compared are both 22.5 °, and the advance flank angle of the screw implant 1 of the present invention is 10 ° and the follower flank angle. Was set to 35 °. In the case where the thread height is the same, if the advance side flank angle is smaller than the follow side flank angle, the contact area between the advancing direction screw thread and the alveolar bone is removed, and the screw thread on the direction side and the alveolar bone It will be smaller than the contact area.

  Then, the screw plant was embedded in the artificial bone, and immediately after the completion of the implantation, the tightening torque in the tightening direction and the loosening torque in the loosening direction were measured. A higher torque for both the tightening torque and the loosening torque indicates that the fixing property to the artificial bone is higher, and it indicates that the tightening torque and the loosening torque are less likely to loosen due to repeated vibration caused by the jaw movement. The results are shown in Table 1.

  From Table 1, even if the taper angle is the same, the direction of the present invention in the form in which the contact area between the screw thread on the advancing direction side and the alveolar bone is smaller than the contact area between the screw thread on the pulling direction side and the alveolar bone is Direction of loosening direction, compared with the comparative product with the same contact area between the screw thread on the side and the alveolar bone, and the contact area between the screw thread on the side and the alveolar bone being the same. It is shown that the loosening torque is about 30% higher on the side. Thereby, it was shown that the screw implant 1 of the present invention is less likely to loosen due to repeated vibration due to jaw movement.

  Next, the simulation result of the second test will be described. For the screw implants to be simulated, the same settings were made, with the pitch being 0.5, the outer diameter of the screw body nearest to the head being 1.4 mm, the thread height being 0.2 mm, and the leading flank angle being 10 The follow-up flank angle is 35 °, the material is stainless steel, and the screw body 2 has a different configuration. The screw implant 2 for comparison has a cylindrical straight shape, and the screw implant 1 of the present invention has a conical taper. Shaped.

  And the tightening force of the advancing direction side with respect to the alveolar bone of a screw thread or the removal direction side was simulated. The higher the tightening force, the more difficult it is to loosen against repeated vibrations. As the screw implant 1 according to the present invention, one having a taper angle θ of 1 ° and 2 ° was used. The results are shown in Table 2.

  From Table 2, the taper shape according to the present invention has a tightening force of about 20% higher at a taper angle of 1 ° and about 60% higher at a taper angle of 2 ° as compared to a straight shape of the screw body 2. It has been shown to be. From this, it was shown that the shape of the screw body 2 is less likely to loosen due to repeated vibration due to jaw movement when the taper shape is a tapered shape.

DESCRIPTION OF SYMBOLS 1 Screw implant 2 Screw body 2a Thread 2b Thread groove 2c Notch part 3 Head 3a Fastening part 3b Top part 3c Operation part 4 Continuous part C Gum H Thread height L Center line M Correction member P Pitch S Inclination line T Teeth F1 Trailing flank surface F2 Leading flank surface R Curvature radius θ Taper angle α Trailing flank angle β Leading flank angle

Claims (2)

It is a screw type screw implant used for orthodontic and dental prosthesis,
The area of the follower flank surface forming the thread is made more than 1 to 2 times wider than the area of the advance flank surface,
The screw implant is characterized in that the taper angle of the taper shape with the screw tip side tapered is 0.5 ° to 5.0 °.   The advance flank angle of the screw thread is 5 ° to 20 °, the follower flank angle is 20 ° to 40 °, and the height of each thread of the taper screw is 10 to the outer diameter of the screw thread closest to the head. 2. The screw implant according to claim 1, wherein the area of the follower flank surface is set to be less than 25% and wider than the area of the advance flank surface.

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