JP2018161359A - Primer composition for orthodontic bracket adhesion and orthodontic kit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a primer for orthodontic bracket adhesion, the primer that can exhibit high bonding strength during an orthodontic treatment period and can be removed simply and safely when being removed, and provide an orthodontic kit having this.SOLUTION: A primer composition for orthodontic bracket adhesion is provided for making an orthodontic bracket 1 adhere to a tooth surface 5, and comprises a thermally expandable microcapsule 6 and a resin ingredient. The content of the thermal expansion microcapsule exceeds 10 mass% to the gross weight of the primer composition for orthodontic bracket adhesion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a primer composition for orthodontic bracket adhesion and an orthodontic kit.

In orthodontic treatment, an orthodontic bracket (hereinafter sometimes referred to as “bracket”) is adhered to the tooth surface using an adhesive, and the orthodontic bracket is removed from the tooth surface after the treatment is completed. Since the orthodontic treatment period usually requires a period of about 1 year to 2 years or more, a strong adhesive force is required for adhesion of the orthodontic bracket.
On the other hand, when removing from the tooth surface after completion of treatment, it is required to remove easily without causing damage to tooth enamel or tooth pain.

Conventionally, metal brackets have been used, but recently, the use of ceramic brackets is expanding from the viewpoint of aesthetics. Since ceramic materials are harder and more brittle than tooth enamel, the bracket breaks when the bracket is removed by a strong load, and often remains on the tooth surface. The ceramic bracket broken piece remaining on the tooth surface is removed by cutting a hard ceramic piece with a dental cutting machine. However, there is a risk of cutting the tooth together with the ceramic piece, and the removal operation of the remaining ceramic material is extremely difficult. It is. Also, when removing the bracket with a heavy load, it causes strong tooth pain and enamel fracture.
Patent Document 1 describes an orthodontic adhesive in which thermally expandable microcapsules are mixed in an orthodontic adhesive for the purpose of weakening the adhesive strength when the orthodontic bracket is removed from the tooth surface. Yes.

JP 2007-320929 A

Although the method described in Patent Document 1 can be removed with a weak load, the removal method in which the oral cavity is heated at 80 ° C. for 8 seconds may affect the dental pulp and cause pain due to heat. there were.
The present invention has been made in view of the above circumstances, and can exhibit high adhesive strength during the orthodontic treatment period, and can be easily and safely removed when removing the primer for orthodontic bracket bonding, and the primer. It is an object to provide an orthodontic kit having the same.

The present invention includes the following [1] to [4].
[1] An orthodontic bracket adhering primer composition used for adhering an orthodontic bracket to a tooth surface, comprising a thermally expandable microcapsule and a resin component, wherein the content of the thermally expandable microcapsule is The primer composition for straightening bracket adhesion, characterized in that the amount exceeds 10% by mass with respect to the total amount of the primer composition for straightening bracket adhesion.
[2] The primer composition for orthodontic bracket adhesion according to [1], wherein the content of the thermally expanded microcapsule is 12% by mass or more and 28% by mass or less with respect to the total amount of the primer composition for orthodontic bracket adhesion. object.
[3] The primer composition for bonding an orthodontic bracket according to [1] or [2], wherein the expansion start temperature of the thermally expanded microcapsule is 70 ° C. or higher and 100 ° C. or lower.
[4] An orthodontic kit comprising the orthodontic bracket adhering primer composition according to any one of [1] to [3] and an orthodontic adhesive.

  According to the present invention, there is provided an orthodontic bracket adhering primer and an orthodontic kit having the same, which can exhibit high adhesive strength during orthodontic treatment and can be easily and safely removed when removed. Can do.

It is a schematic diagram explaining an example of the usage condition of the primer composition for correction | amendment bracket adhesion of this embodiment. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example.

<Primer composition for orthodontic bracket adhesion>
The present invention is an orthodontic bracket adhering primer composition (hereinafter sometimes referred to as “primer composition”) used for adhering an orthodontic bracket to a tooth surface. The primer composition is a material previously applied to the tooth surface as a base agent of the orthodontic adhesive when the orthodontic bracket is bonded to the tooth surface using the orthodontic adhesive.

  The primer composition of this embodiment contains a thermally expandable microcapsule and a resin component. Hereinafter, each component used for this embodiment is demonstrated.

≪Thermal expansion microcapsule≫
In the present embodiment, the thermally expandable microcapsule used as a material (hereinafter sometimes referred to as “microcapsule”) is preferably a thermally expandable microcapsule having a gas whose volume expands when heated, for example.
When the orthodontic bracket is removed, if the temperature in the pulp cavity is rapidly increased by the heating means, the pulp may be seriously inflamed and may cause pain or burns in the oral cavity.
In this embodiment, from the viewpoint of safely removing the orthodontic bracket body, the expansion start temperature of the microcapsule is preferably 70 ° C. or higher and 100 ° C. or lower, more preferably 75 ° C. or higher and 85 ° C. or lower, and particularly preferably 78 ° C. or higher and 82 ° C. or lower. The temperature is preferably 80 ° C.

Here, the thermally expandable microcapsule is a microcapsule having an average particle size of 10 μm or more and 30 μm or less that expands 4 to 5 times in diameter and 50 to 100 times in volume by heating for a short time at a predetermined temperature or higher. preferable.
As such microcapsules, volatile organic agents (swelling agents) such as isobutane, pentane, petroleum ether, hexane, heptane, low-boiling halogenated hydrocarbons, and methylsilane are used as vinylidene chloride, acrylonitrile, acrylic esters, methacrylic esters. And those encased in a film polymer made of a thermoplastic resin made of a copolymer.

When the microcapsule is heated above the softening point of the membrane polymer, the membrane polymer begins to soften. At the same time, the vapor pressure of the encapsulating expansion agent rises, the membrane expands, and the capsule expands. .
As described above, the thermally expandable capsule is formed by a combination of the core substance (expansion agent) and the membrane polymer. By considering the boiling point of the thermal expansion agent and the softening point of the membrane polymer, the expansion start temperature is set to 70 to It can be set to 100 ° C. Further, since the heat-expandable capsule has a small average particle size of 10 μm to 30 μm, it can be mixed and dispersed even in a thin film primer layer.

  In the present embodiment, thermally expandable microcapsules such as brands F-30 and F-36 of Matsumoto Yushi Seiyaku Co., Ltd. can be suitably used.

≪Resin ingredient≫
The resin component contained in the primer composition of the present embodiment includes methyl methacrylate (MMA), hydroxymethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA), di (methacryloxyethyl) trimethylhexamethylene diurethane (UDMA). ), N, N- (2,2,4-trimethylhexamethylene) bis [2- (aminocarboxy) propane-1,3-diol] (UTMA), 2,2-bis [4- (2-hydroxy-) 3-methacryloxypropoxy) phenyl] propane (Bis-GMA), ethylene glycol dimethacrylate (EDMA), or a combination thereof.
In the present embodiment, TEGDMA or Bis-GMA is preferably included, and TEGDMA and Bis-GMA are more preferably included.

≪Compound ratio≫
In the primer composition of the present embodiment, the content of the thermal expansion microcapsule is an amount exceeding 10% by mass with respect to the total amount of the primer composition, preferably 12% by mass or more, more preferably 15% by mass or more, 18 mass% or more is especially preferable. Moreover, 28 mass% or less is preferable and 25 mass% or less is more preferable.
The upper limit value and the lower limit value of the content can be arbitrarily combined. In the present embodiment, the content is preferably 12% by mass or more and 28% by mass or less.
When the content of the microcapsule is not less than the above lower limit value, the adhesive strength is sufficiently lowered when the correction bracket body is removed, and the removal with a weak force is facilitated.
Adhesive strength suitable for orthodontic clinics can be maintained when the content of the microcapsules is not more than the above upper limit.

≪Optional ingredient≫
In addition to the above essential components, the primer of this embodiment may contain components such as other monomers and solvents as long as the effects of the present invention are not impaired. Moreover, what is necessary is just to add a photoinitiator, when setting it as a photopolymerizable primer composition.

The primer composition of the present embodiment can be produced by mixing the above microcapsules, a resin component, and an optional component.
In the primer composition of this embodiment, the microcapsules reduce the adhesive strength due to the physical action of thermal expansion. For this reason, even if it mixes with the existing primer composition, the primer composition itself and the microcapsule do not cause a chemical reaction, and the effect of the primer composition itself is not affected at all. Therefore, you may manufacture by mixing a microcapsule with the existing primer composition.

  The existing primer composition may be either a photopolymerizable primer composition or a photopolymerizable inner primer composition.

An example of usage of the primer composition of the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the correction bracket main body 1 is provided with a groove 1a for inserting the correction wire 2 on the surface. Furthermore, the wing 1b for hooking a ligation tool on the right and left is formed.
When the orthodontic bracket body 1 is bonded to the tooth surface 5, first, the primer layer 3 is formed by applying the primer composition of the present embodiment to the tooth surface 5. In the present embodiment, the primer layer 3 includes thermally expandable microcapsules 6.
In the state where the orthodontic adhesive is applied to the lower part of the orthodontic bracket body 1 via the coupling agent layer 7 which is an arbitrary layer, the orthodontic adhesive application surface is pressed against the primer layer 3, and the orthodontic bracket body 1 is attached. Adhesive and fixed to the tooth surface 5.

  In this embodiment, when removing the correction bracket main body 1, the bracket main body 1 is heated by a heating means. Thereby, in the vicinity of the adhesion surface 3c between the bracket body 1 and the tooth surface 5, the thermally expandable microcapsule included in the primer layer expands. Due to the expansion of the microcapsules, the adhesive strength is reduced in the vicinity of the adhesive surface 3c, and the bracket body 1 can be removed.

The heating means for removing the correction bracket body 1 is not particularly limited as long as it can expand the microcapsules in the primer composition, and a heater, a CO ₂ laser, or the like can be used. In the present embodiment, it is preferable to use a CO ₂ laser from the viewpoint of safety. When using a CO ₂ laser, the irradiation conditions are, for example, 5 W or more and 7 W or less, and the lower limit is preferably 1 second or more, more preferably 3 seconds or more, and particularly preferably 4 seconds or more. For example, the upper limit is preferably 6 seconds or less, and more preferably 5.5 seconds or less. The upper limit value and the lower limit value of the irradiation time can be arbitrarily combined.
When a CO ₂ laser is used, the above irradiation condition is a range in which there is no possibility that an increase in the temperature in the pulp cavity may affect the pulp.

  In this embodiment, since the microcapsule is contained in the primer composition, the bracket can be removed by irradiation in a short time of 6 seconds or less.

When the primer composition of the present embodiment is used, since the microcapsule expands in the vicinity of the adhesive surface 3c between the bracket body 1 and the tooth surface 5 and the adhesive strength decreases, it can be removed safely and easily under the above irradiation conditions. be able to. According to the present invention, bracket fragments are unlikely to remain on the tooth surface, and the ceramic bracket can also be removed safely and easily.
In the primer composition of this embodiment, the adhesive strength is reduced by the physical action of thermal expansion of the microcapsules. For this reason, even if it mixes with the existing primer composition, primer composition itself and a microcapsule do not raise | generate a chemical reaction, but can maintain the adhesive force of primer composition itself.

  In this embodiment, the material of the orthodontic bracket body 1 is not particularly limited, and a known material such as a metal, a plastic (made of polycarbonate or acrylic), or a ceramic can be used. In this embodiment, among these, it can apply suitably for the correction bracket made from ceramics.

<Orthodontic kit>
The present embodiment is an orthodontic kit having the orthodontic bracket adhering primer composition of the present invention and an orthodontic adhesive. As an arbitrary configuration, a coupling agent may be included.

≪Orthodontic adhesive≫
There are various types of orthodontic adhesives (powder / liquid admixture type and paste type) and polymerization forms (chemical polymerization and photopolymerization). In the present embodiment, the orthodontic adhesive is not particularly limited, and a known material can be used.
Since the primer composition of the present invention does not affect the adhesive strength of the primer composition itself, the combination with the existing orthodontic adhesive is not particularly limited.

≪Coupling agent≫
In the present embodiment, examples of the material used for forming the coupling agent layer 7 which is an arbitrary layer include silane coupling agents such as gammamethacryloxypropyltrimethoxysilane. This coupling agent is strongly chemically bonded to an organic orthodontic adhesive.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to a following example.

The materials used in this example are as follows.
-Orthodontic bracket base Bracket base for 0.018 inch slot zirconia ceramic maxillary central incisors.
Product name: Coby, manufactured by Biodent.
-CO ₂ laser Product name: OPERASER PRO, manufactured by YOSHIDA.
-Orthodontic adhesive Photopolymerization resin adhesive Product name: TransbondXT, manufactured by 3M Unitek.
-Commercially available primer for orthodontic bracket bonding Product name: TransbondXT primer, manufactured by 3M Unitek.
-Thermal expansion microcapsule Product name: Matsumoto Microsphere F-36D, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.

<Examples 1-3, Comparative Examples 1-2>
A thermal expansion microcapsule (described as “microcapsule” in the following examples) was mixed with a commercially available primer for adhering an orthodontic bracket so as to have a blending amount shown in Table 1 below. The primer composition for straightening bracket adhesion of Example 2 was prepared. In Table 1 below, the content of the microcapsule is the content (% by mass) relative to the total amount of the orthodontic bracket-adhering primer composition. The one not containing microcapsules was designated as Comparative Example 1.

<Experimental Example 1: CO temperature measurement of the bracket base by ₂ laser irradiation conditions>
To determine the CO ₂ laser irradiation conditions, being in contact with the thermocouple just below the bracket base, the irradiation output 5W (Yes Air cooling, without the air cooling), 7W (Yes Air cooling, without the air cooling) the CO ₂ laser with The bracket base temperature when irradiated for 3 to 6 seconds was measured.
The results are shown in FIGS. When the bracket base temperature was measured, the laser irradiation conditions exceeding 80 ° C. were irradiation power 7 W, irradiation for 5 seconds, or irradiation for 6 seconds (FIGS. 4 and 5).

<Experimental Example 2: Measurement of Intramedullary Temperature by CO ₂ Laser Irradiation>
The bracket was adhered to the buccal side of a human premolar with a photopolymerization resin adhesive, and the temperature increase in the dental pulp cavity (room temperature 23 ° C.) after laser irradiation was measured.
From the results of Experimental Example 1, when the temperature increase in the pulp cavity was measured at an irradiation output of 7 W for 5 seconds or 6 seconds, it was assumed that there was no possibility of affecting the dental pulp. The conditions were as follows: 7 W (with air cooling) and an average of 5.3 ° C. after 5 seconds of irradiation (FIG. 6). Therefore, the CO ₂ laser irradiation condition in this example was 7 W (with air cooling) for 5 seconds.

<Experimental example 3>
Next, the primer of Comparative Example 1 was irradiated with laser while applying a load of 3 kg or 4 kg, and the dropping time was measured.
When a load was applied to the bracket bonded with the primer of Comparative Example 1 and the laser was irradiated with an irradiation power of 7 W to measure the bracket drop time, it was not dropped even after 20 seconds of irradiation at a load of 3 kg. On the other hand, it dropped out in about 6 seconds when loaded with 4 kg (FIG. 7).
In the case of using a primer to which the present invention is not applied, a strong load was required when removing the bracket.

<Experimental example 4>
Various types of irradiation were performed by attaching a bracket with a primer composition of each of Examples 1 to 3 and Comparative Examples 1 to 2 to a bovine mandibular anterior tooth crown subjected to 37% phosphoric acid etching treatment and a photopolymerization adhesive. Laser irradiation was performed under the conditions, and the shear bond strength after 10 minutes was measured with a dental material universal testing machine.
Dunnett's test was performed for multiple comparison of the shear bond strength 10 minutes after laser irradiation, and the significance level was p <0.05.

  When using the primer compositions of Examples 1 to 3 and Comparative Examples 1 and 2 without laser irradiation and laser irradiation for 5 seconds, the shear bond strength after 10 minutes after irradiation was measured and compared, In Examples 1 to 3, the values significantly decreased to 0.38 times, 0.21 times, and 0.25 times (6.0 MPa, 3.3 MPa, and 3.3 MPa), respectively (FIG. 8).

  On the other hand, Comparative Example 1 in which no microcapsules were added and Comparative Example 2 in which the amount of microcapsules added was outside the scope of the present invention had a slight shear bond strength after 10 minutes had passed after laser irradiation. Declined. However, it is said that enamel may be damaged when removing one having an adhesive strength of 9.7 MPa or more. In Comparative Examples 1 and 2, the adhesion strength was much greater after 10 minutes after laser irradiation.

  Moreover, it is supposed that the adhesive strength suitable for orthodontic clinic is 6 MPa to 8 MPa. Considering this, the primer of Example 2 is considered to be a more preferable formulation. (FIG. 8).

  In Comparative Example 1, when it was irradiated with a laser while applying a 4 kg load, it dropped out in about 6 seconds (FIG. 7). However, when the shear bond strength at the time of non-irradiation and 10 minutes after laser irradiation in Comparative Example 1 was compared, no significant difference was observed (FIG. 8). From this, it was found that the significantly reduced shear bond strength was recovered within 10 minutes after laser irradiation. On the other hand, in Examples 1 to 3, the shear bond strength was significantly reduced even after 10 minutes as compared with the non-irradiated case (FIG. 8).

  Immediately after laser irradiation, the bracket is heated and may cause burns when removed. In order to safely and effectively remove the bracket by laser irradiation, it is preferable that the shear bond strength reduced by laser irradiation is maintained even after cooling the bracket. From the results of the present example, in Comparative Example 1, the shear bond strength is recovered after a lapse of a certain time after laser irradiation. However, when the primer compositions of Examples 1 to 3 are used, after laser irradiation for 5 seconds. Even if the bracket is cooled and removed after a certain time (10 minutes), the shear bond strength reduced to ¼ is maintained, and it can be removed with weak force without causing enamel damage or pain. It was thought to be.

  As shown in the above results, when the primer compositions of Examples 1 to 3 were used, high adhesion strength to the ceramic bracket was able to be exhibited before the removal work, and it was possible to remove it simply and safely when removing it. did it.

1: orthodontic bracket body, 1a: groove, 1b: wing, 2: wire, 3: orthodontic bracket adhesive primer layer, 3c: adhesive surface, 4: orthodontic adhesive layer, 5: tooth surface, 6: thermal expansion Microbubbles, 7: coupling agent layer,

Claims (4)

An orthodontic bracket adhering primer composition used for adhering an orthodontic bracket to a tooth surface,
Including thermally expandable microcapsules and a resin component;
The primer composition for straightening bracket adhesion, wherein the content of the thermal expansion microcapsule is an amount exceeding 10% by mass with respect to the total amount of the primer composition for straightening bracket adhesion.   The primer composition for bonding an orthodontic bracket according to claim 1, wherein the content of the thermally expanded microcapsule is 12% by mass or more and 28% by mass or less based on the total amount of the primer composition for adhering the orthodontic bracket.   The primer composition for bonding an orthodontic bracket according to claim 1 or 2, wherein an expansion start temperature of the thermal expansion microcapsule is 70 ° C or higher and 100 ° C or lower.   The orthodontic kit which has the primer composition for orthodontic bracket adhesion | attachment of any one of Claims 1-3, and an orthodontic adhesive.

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