JPH06125921A - Orthodontic wire - Google Patents

Abstract

PURPOSE:To provide an orthodontic wire the final product of which is readily available with a very high superelastic function, made from a shape memory material that can be used over a long period of time in very strong acid and alkali extreme environments. CONSTITUTION:An orthodontic wire 12 is made from a shape memory material obtained by quench hardening of a molten alloy which exhibits a shape memory phenomenon, and since such a shape memory material has a very high superelastic function and is remarkably excellent in corrosion resistance, the orthodontic wire 12 is allowed to exhibit exceptionally excellent functions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an orthodontic wire used for attaching to an orthodontic column and correcting it, and more particularly to an orthodontic wire using a shape memory material.

[0002] Conventionally, when performing orthodontic treatment such as malocclusion, a method of using the elastic force of a metal wire to correct it has been adopted. Conventionally, stainless steel or CoCr alloy wire has been used as a straightening metal wire, but these materials have the drawback of high elastic modulus and low elastic elongation. Therefore, a large correction force can be obtained with a slight deformation, but on the other hand, since plastic deformation is likely to occur, it is necessary to first transform into an arched shape in order to give an appropriate correction force, and skill is required for mounting.

Therefore, by utilizing the superelasticity function of the shape memory alloy for this straightening wire, plastic deformation does not occur even if a strain of up to 10% is applied, and the elastic modulus is a nonlinear characteristic due to stress-induced martensitic transformation. Therefore, even if the strain increases, the rate of increase in the correction force is small. Therefore, even if a large deformation is applied at the time of wearing, it can be worn while maintaining an appropriate correction force, and not only the wearing operation is simple but also the therapeutic effect is great and the discomfort of the patient can be reduced.

When a shape memory alloy is used as an orthodontic wire as described above, the conventional problems when using a general material can be solved. Therefore, an orthodontic wire made of a shape memory alloy has recently been used. It is performed to correct the dentition.

[0005]

Conventionally, a shape memory alloy forming an orthodontic wire is generally obtained by a melting / hot working process to obtain a product material having a final shape.

According to this melting / hot working process, an ingot produced by high-frequency vacuum melting, plasma melting or the like is processed into a required shape by hot working means such as pressing, rolling or forging. It was a thing.

However, when a shape memory alloy such as a Ti-Ni-Cu system is obtained by this melting / hot working process, it is difficult to form a wire because the Ti-Ni alloy is difficult to work. Especially, when Cu is 10 at% or more, it becomes brittle and extremely difficult to work, so that it is difficult to obtain a final product.

Furthermore, since the crystal structure is coarse and the matrix has a low dislocation density, the yield stress is low, so the superelastic function is not sufficient, and the corrosion resistance is essentially T.
The i-Ni system is good, but due to the coarse crystal grains of the processing material and the non-uniformity of the surface, problems remain for long-term use in extremely strong acidic / alkaline extreme environments, and its application as an orthodontic wire. Was one of the obstacles.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and the final product can be easily obtained, has an extremely high superelastic function, and has extremely strong acidity.
An object of the present invention is to provide an orthodontic wire made of a shape memory material that can be used for a long period of time in an alkaline extreme environment.

[0010]

In order to develop a new material capable of achieving the above object, the inventors of the present invention directly inject a molten alloy system showing a shape memory phenomenon from a nozzle to a Cu cooling roll. , A rapid quench solidification process (Melt-spinnin) to obtain the final sheet (about 20-300 microns thick)
g Technique) was adopted. as a result,
Due to the rapid cooling effect by the rotary rapid solidification method, a homogeneous and extremely fine anisotropic (columnar crystal of several microns or less) structure can be obtained, and the lower structure has a high dislocation density. The present invention has been completed based on the finding that superelasticity and corrosion resistance can be improved because plastic strain hardly occurs and energy loss other than phase transformation does not occur.

The orthodontic wire according to the present invention for this purpose is made of a shape memory material obtained by rapidly solidifying an alloy-based molten metal showing a shape memory phenomenon.

Examples of alloys exhibiting the shape memory phenomenon here are shown in Tables 1 and 2.

[0013]

[Table 1]

[0014]

[Table 2]

Upon rapid solidification of the alloy-based molten metal exhibiting the shape memory phenomenon, the cooling rate is 10 ² to 10 ⁶ ° C / sec.
Is desirable. If the cooling rate is not appropriate, fatigue resistance and corrosion resistance will decrease.

Ti-N is used as the shape memory material.
A Ti-Ni-based shape memory alloy obtained by quenching and solidifying a molten i-based alloy is suitable, and Ti (50 ± y, y ≦ ± 2 at%)-Ni is suitable as the shape-memory material.
A Ti-Ni-Cu-based shape memory alloy obtained by rapidly solidifying a (50-y-x) -Cu (xat%)-based alloy melt is particularly suitable. As a result, a homogeneous and extremely fine anisotropic (columnar crystal of several microns or less) structure can be obtained. Furthermore, since the lower structure has a high dislocation density, plastic strain due to yielding is unlikely to occur, and there is no energy loss other than phase transformation, so an extremely high superelastic function is provided and corrosion resistance can be improved.

The orthodontic wire of the present invention is Ti
(50 ± y, y ≦ ± 2 at%)-Ni (50-y-x)
-Cu (xat%)-based alloy molten metal is rapidly solidified, and Cu content x is Ti-N with 0 <x≤20at%
It is preferable to use an i-Cu-based shape memory alloy. In this area, material embrittlement (grain boundary embrittlement, etc.) occurs in a normal melting / hot working process, making large rolling difficult.

Further, the orthodontic wire of the present invention has a T
i (50 ± y, y ≦ ± 2 at%)-Ni (50-y-
x) -Cu (xat%)-based alloy melt is rapidly solidified and the Cu content x is preferably set to 11.0 to 16.0 at%, most preferably 12.0 to 14.
It is good to set it to 0 at%.

Examples of the rapid solidification method used in the present invention include, for example, a gun method in which a molten metal is directly sprayed onto a Cu cooling plate or the like to be rapidly cooled to produce a small test piece, a rotary roll (single or twin roll) method for producing a continuous thin plate, There are a spinning submerged spinning method suitable for producing fine wires, a spray method for producing a quenched powder, and the like.

Among the above quenching methods, when the rapid solidification is performed by the rotating roll method (single roll), the cooling rate is preferably 1 to 50 m / sec. Cooling rate is 1
If it is less than m / sec, the quenched metal structure (particularly the crystal grain size) becomes coarse and random orientation occurs, and the superelastic function, fatigue deterioration resistance, and corrosion resistance deteriorate. On the contrary, when the cooling rate exceeds 50 m / sec, the metal structure becomes amorphous and the superelastic function does not appear, which is not preferable.

[0021]

In general, when the molten metal is rapidly solidified by the molten metal quench solidification method, the metal structure is finely crystallized from the dendrite phase as the cooling speed (roll rotation speed in the rotating roll method) is increased as shown in FIG. Then, the equiaxed columnar crystals are transformed into amorphous at a super-quenching rate (1 × 10 ⁶ ° C / sec or more). For example Ti-Ni-C
The quenching rate of u melt is 40m / sec (1 × 10 ⁶ ℃ / s
ec), the metal structure becomes fine columnar crystals (crystal grain size is 2 to 3 μm) in which crystal axes are aligned in the plate thickness direction. Even if X-ray crystal structure analysis is performed on this point, it is confirmed that the crystal directions are aligned. Therefore, the Ti-Ni-Cu-based shape memory alloy cooled at this quenching rate has such a metal structure, and thus has the following function.

Since the crystal orientations are aligned due to the formation of columnar crystals, the Ti-Ni-Cu-based shape memory alloy undergoes uniform transformation as a whole at the same time and has a fine crystal structure, so that the material yield stress is high. The load stress stability is improved.

Further, as a result of the fine crystals having a high yield stress and a uniform crystal orientation, plastic strain / transition is less likely to be introduced and functional fatigue deterioration (memory blur) is less likely to occur during repeated use.

Ti (50 ± y, y applied to the present invention
≦ ± 2 at%)-Ni (50-y-x) -Cu (xat
%) Type shape memory alloy, if the addition amount x of Cu is set to about 15 at%, in the vicinity thereof, a route from cubic crystal to orthorhombic crystal to monoclinic crystal is followed.

As described above, the shape memory material applied to the present invention has an extremely high superelastic function and extremely excellent corrosion resistance. Therefore, when it is used as an orthodontic wire, it has an unprecedented excellent function. Exert.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the orthodontic wire according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an orthodontic wire according to an embodiment of the present invention, in which an orthodontic wire 12 of the present invention is used with respect to an dentition 11.
Is installed.

Conventionally, stainless steel and Co-Cr alloy have been used as orthodontic wires, but these are highly rigid and have an elastic strain limit which is the same as that of general metal materials and is within 1% at most. For this reason, it is difficult to install in the oral cavity and requires skill, and the wire must be exchanged many times to adjust the correction force during treatment, and the patient feels discomfort and wears the wire. There was a defect such as a feeling of strangeness at the time. Therefore, as this straightening wire, the rapidly solidified shape memory alloy discovered by the present inventors, particularly the T
If the orthodontic wire 12 of the embodiment of the present invention utilizing the great superelasticity of the iNi-based material is used, it has high strength and is supple, so that the mounting operation is easy and the wire replacement is small, so that the Discomfort is reduced and the therapeutic effect is great.

An example of the rapidly solidified shape memory alloy applied to the above examples is shown below. In the following example, a case where a rotating roll method is used as a rapid solidification method for a shape memory alloy melt will be described.

Using the rotary rapid solidification equipment shown in FIG.
Molten Ti-Ni-Cu alloy having the composition shown in Table 3 obtained by arc-melting a TiNiCu ingot material in an atmosphere 1
Is sprayed directly from a quartz nozzle 2 around which a coil 1 for sample induction heating is wound in a high-purity Ar atmosphere onto a rotating copper roll 3 to rapidly cool and solidify in a molten metal contact portion 4 to form a rapidly solidified ribbon 5. Obtained. At that time, the cooling rate is 1 × 10 ⁴ to
Roll speed is set to 1 to 10 ⁶ ℃ / sec
m / sec, rotating copper roll for cooling (diameter = 200m
m) The rotation speed was 2000 to 4000 rpm. The Ti-Ni-Cu-based shape memory alloy wire as the orthodontic wire thus obtained was evaluated for corrosion resistance.

[0031]

[Table 3] (Alloy chemical composition)

The results of evaluation of corrosion resistance are shown in FIG. FIG. 3 shows the rapidly solidified Ti as the orthodontic wire of this embodiment.
-Ni-Cu system shape memory alloy, hydrochloric acid (1N / HC
It is a measurement of the curve of the division in 1). As shown in the figure, even if the lowest point of each bending curve, that is, the so-called natural electrode potential level is compared, the corrosion resistance can be greatly improved by 100 times to 10,000 times compared with the conventional melt processed material. I understand.

The above rapidly solidified shape memory alloy is effectively applied as an interdental brush and a denture base reinforcing composite material (composite).

Interdental brush Food residues (= plaque) are accumulated between the teeth, which cause caries, gingivitis, and alveolar pyorrhea. As an instrument for removing the plaque, an "interdental brush" shown in FIG. 5 is used, but a stainless thin wire has been conventionally used for the wire 13 portion. However, since the tooth root portion and the flesh portion of the gap between the teeth have large irregularities, it is difficult to contact the wire along the curve of the gingiva with a stainless wire having a small elastic strain, and plaque cannot be removed. On the other hand, when the rapidly solidified TiNi alloy of the present invention is used for the portion of the fine wire (wire) 13, due to its large superelasticity, it can be adhered to the gingiva and the curved surface portion of the tooth and the plaque can be removed well.

In order to stably support the denture base 14 for denture base reinforcement and to disperse the concentrated force from the teeth during chewing, the clasp (= removable prosthesis) as shown in FIG. (Resin) 16 for denture base having 15) disposed at both ends is used, but the strength is high in order to reduce discomfort and discomfort of the denture patient and to make smooth oral chewing and vocal movement. Flexible denture base materials are required. Therefore, the rapidly solidified shape memory alloy, especially its TiNi-based fibers and thin plates, are arranged inside the resin in a mesh shape to bring out the composite strengthening and elastic deformability of the large alloy, and it is supple and can sufficiently follow the muscle movement in the oral cavity. Thus, a denture base reinforced composite material that can reduce discomfort to the patient can be obtained.

The shape memory alloy can also be used for the clasps at both ends of the denture base for gripping healthy teeth.

[0037]

As described above, according to the orthodontic wire of the present invention, the following effects can be obtained.

An orthodontic wire is, for example, Ti-Ni-
Rapid solidification Ti obtained by rapid solidification of Cu-based alloy melt
Since the orthodontic wire of the present invention is made of a -Ni-Cu type shape memory alloy, the functional deterioration (memory blur) due to repeated use is significantly reduced (about 1/10) and the superelasticity is extremely high. The excellent effect of having a function is exhibited.

Further, according to the orthodontic wire of the present invention, the corrosion resistance in an oxidizing atmosphere (1N-HCl) hydrochloric acid is greatly improved (100 to 10,000 times), and therefore, the carcinogenic substance in vivo is prevented. There is an excellent advantage that the occurrence and the like are prevented.

[0040]

[Brief description of drawings]

FIG. 1 is a view showing an orthodontic wire according to an embodiment of the present invention.

FIG. 2 is a schematic view of a rapid solidification apparatus used to obtain the orthodontic wire of the present invention.

FIG. 3 is a Ti—Ni—Cu-based shape memory alloy hydrochloric acid (1 N / N applied to the orthodontic wire according to the embodiment of the present invention).
FIG. 3 shows a polarization curve in HCl).

FIG. 4 is a T applied to the orthodontic wire of the present invention.
It is a figure which shows the change of the metal structure with the cooling rate of i-Ni-Cu type shape memory alloy.

FIG. 5 is a diagram showing a state in which the orthodontic wire according to the embodiment of the present invention is applied to a wire of an “interdental brush”.

FIG. 6 is a view showing a state in which the orthodontic wire according to the embodiment of the present invention is applied to the resin for denture base.

[Explanation of symbols]

 1 Sample induction heating coil 2 Quartz nozzle 3 Rotating Cu roll 4 Molten metal contact part 5 Rapid solidification ribbon

 ─────────────────────────────────────────────────── ─── Continuation of front page (71) Applicant 391063662 Yoshikatsu Tanahashi 10-26 Yagiyama Kasumi-cho, Taishiro-ku, Sendai-shi, Miyagi Prefecture (72) Inventor Yasufumi Furuya 14-1-33 Sanjo-cho, Aoba-ku, Sendai City, Miyagi Prefecture ( 72) Inventor Ken Masumoto 3-8-22, Uesugi, Aoba-ku, Sendai-shi, Miyagi Prefecture 72-72 (72) Hidemi Ito 11-17-2, Kasumome, Wakabayashi-ku, Sendai City, Miyagi Prefecture (72) Inventor Yoshikatsu Tanahashi Sendai-shi, Miyagi Prefecture 10-26 Kasumi-cho, Yagiyama, Taishiro-ku

Claims (6)

[Claims] 1. An orthodontic wire used for mounting on an orthodontic column and straightening it, characterized by using a shape memory material obtained by rapid solidification of an alloy-based molten metal exhibiting a shape memory phenomenon. Row straightening wire. 2. A cooling rate of 10 ² to 10 ⁶ ° C./se for rapid solidification of an alloy-based molten metal exhibiting a shape memory phenomenon.
The orthodontic wire according to claim 1, wherein the wire is c. 3. An orthodontic wire used for orthodontics attached to a dentition, which is obtained by rapidly solidifying molten Ti—Ni alloy as a shape memory material.
The orthodontic wire according to claim 1, wherein an i-Ni-based shape memory alloy is used. 4. An orthodontic wire used for attaching to an orthodontics and correcting the same, comprising Ti (50 ±
y, y ≦ ± 2 at%)-Ni (50-y-x) -Cu
Ti obtained by rapidly solidifying molten alloy of (xat%) type
An orthodontic wire characterized by using a Ni-Cu type shape memory alloy. 5. The orthodontic wire according to claim 4, wherein the Cu content x is 0 <x ≦ 20 at%. 6. The Cu content x is 11.0 to 16.0a.
The orthodontic wire according to claim 5, which is t%.