JP3471866B2 - Manufacturing method of artificial root - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an artificial dental root, which is a composite of ceramic materials and metals, which are dental materials usable in the living oral cavity, with an organic adhesive.

[0002]

2. Description of the Related Art Conventionally, when a tooth lost due to various reasons is restored by an artificial tooth, an artificial tooth root is embedded under the alveolar periosteum to thereby rebuild the superstructure. There is. Various types of artificial tooth roots have been proposed and actually used up to the present day, but among them, a bioactive ceramic material that contacts bones and a metal core body that internally maintains and compensates for strength are used. Using
Composite artificial tooth roots are promising. The composite of these different materials includes a method of directly forming a ceramics layer on the metal core body by thermal spraying or a method of composite with an adhesive. In the latter case, the organic compound-based 2,2-bis [4- (3
Methacryloxy-2-hydroxypropyl) phenyl] propane (hereinafter abbreviated as bis-GMA) adhesives have been used. However, this bis-GMA
The system adhesive cannot exhibit a sufficient adhesive effect because a peeling layer is generated at the adhesive interface due to shrinkage during polymerization. For this reason, the breaking strength becomes low, and there is a drawback that it cannot be put to practical use.

As described above, in the artificial tooth root prepared by using the bis-GMA type adhesive, the first factor for lowering the fracture strength is that when the adhesive is polymerized / cured, the adhesive interface of the adhesive interface is caused by polymerization shrinkage. It was found that peeling occurred and voids were generated accordingly. Therefore, in order to prevent this decrease in strength, development of means for compensating for the peeled portion and the void is required.

[0004]

OBJECT OF THE INVENTION The present invention compensates for polymerization shrinkage of adhesives,
It is an object of the present invention to provide a method for producing an artificial tooth root capable of preventing a decrease in strength.

[0005]

SUMMARY OF THE INVENTION The present invention has achieved the above object by using a specific adhesive and additionally injecting a compensation liquid for compensating for voids. That is, the method for producing an artificial tooth root according to the present invention is a method for producing an artificial tooth root, which comprises inserting an adhesive into the concave portion of the artificial tooth root body made of a ceramics sintered body, and then inserting and joining the metal core body, It is characterized in that a compensating solution containing a polymerizable unsaturated compound and a polymerization initiator is injected into the voids generated by the polymerization shrinkage of the adhesive.

In the present invention, the main body of the artificial tooth root is made of a ceramic sintered body. As the ceramics, calcium phosphate ceramics, alumina ceramics, zirconia ceramics and the like can be used. However, in consideration of biocompatibility, new osteoinductivity, etc., it is preferable that at least a portion that comes into contact with a biological tissue has a layer of calcium phosphate ceramics, particularly hydroxyapatite and / or α-tricalcium phosphate.

It is also preferable that the entire main body of the artificial tooth root is composed of a hydroxyapatite sintered body. This hydroxyapatite sintered body does not need to be pure, but preferably contains 50% by weight or more of hydroxyapatite. If it is less than 50% by weight, the bone-like adhesion with the jawbone may become insufficient after being embedded in the jawbone. Further, hydroxyapatite has fine particles or whiskers of tricalcium phosphate, alumina, silica and zirconia.
It may be an artificial tooth root body obtained by adding and mixing at least one kind and sintering. It is expected that the strength will be improved by incorporating the above-mentioned ceramics in the form of fine particles or whiskers. In addition, those obtained by adding tricalcium phosphate to hydroxyapatite and sintering and those provided with a tricalcium phosphate layer on the surface of a hydroxyapatite sintered body are newly formed when the artificial tooth root is embedded in the jawbone. It is particularly preferable because it effectively acts on the formation of bone.

The adhesive used in the present invention is not particularly limited, and examples thereof include methacrylate adhesives and acrylic adhesives. Among these, methyl methacrylate is contained as a main component, and polymethyl methacrylate and 4- (2-methacryloyloxyethyl) trimellitic anhydride (hereinafter abbreviated as 4-META) are contained as accessory components.
This substance has an action of improving the adhesive strength with metals and ceramics) and a methacrylate-based adhesive containing a polymerization initiator is advantageous in that it exhibits excellent adhesion between the metal and the ceramic material in vivo. Is particularly suitable. Sufficient adhesiveness and strength can be achieved by using the adhesive as described above, but an adhesive obtained by adding a ceramic powder of the same kind as the ceramic constituting the artificial tooth root body to the adhesive as the filler is used. Is also preferable. When the ceramic powder is added as a filler, the ceramic powder is 50
It is preferably included in the adhesive in an amount of ˜75% by weight.
If the compounding ratio of the ceramic powder is less than 50% by weight, the effect of improving the strength of the adhesive becomes small, and if it exceeds 75% by weight, the adhesive strength is lowered and the viscosity of the adhesive is increased, so that it cannot be put to practical use.

In the present invention, the metal core is not particularly limited, and a core made of a metal or alloy such as titanium, cobalt-chromium alloy, stainless steel or the like can be used.

In the method of the present invention, the adhesive as described above is put in the recess of the artificial tooth root body as described above, and the metal core is inserted to advance the polymerization of the adhesive. At this time, voids are generated due to polymerization shrinkage of the adhesive. Therefore, a compensation liquid containing a polymerizable unsaturated compound and a polymerization initiator is injected into this void.

The polymerizable unsaturated compound is not particularly limited, and vinyl ester such as vinyl acetate, acrylic ester such as methyl acrylate, methacrylic acid ester such as methyl methacrylate, acrylamide, N-methyl acrylamide and the like. Examples thereof include acrylamide derivatives, methacrylamide, methacrylamide derivatives such as N-methylmethacrylamide, vinyl ethers such as methyl vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, and vinyl halides such as vinyl chloride. One or more of these can be used, but it is preferable to use the same unsaturated compound as the monomer contained as the main component in the adhesive used.

As the polymerization initiator, hydrogen peroxide,
Cumene hydroperoxide, t-butyl hydroperoxide, persulfates (K, Na or ammonium salts), t-butyl peracetate, t-butyl perbenzoate, benzoyl peroxide, dibutyl peroxide, t-butyl peroxy. (2-ethylhexanoate), 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4)
-Dimethylvaleronitrile), 2,2'-azobis-
2,4-dimethylvaleronitrile and the like can be mentioned.

The compensating liquid preferably has a low viscosity so that it can easily penetrate into minute voids in the adhesive layer, and it is necessary that the compensating liquid cures later than the adhesive. Therefore, the compensating liquid preferably does not contain a polymer, and the concentration of the polymerization initiator is preferably lower than that of the adhesive. Further, the polymerization is preferably carried out at a relatively low polymerization temperature for a long time, preferably at 50 ° C. for 10 hours or more in order to effectively inject the compensation liquid.

In order to effectively inject the compensating liquid, it is preferable to initiate the polymerization so that at least a portion where the adhesive contacts the outside is present in the compensating liquid. For example, in FIG.
As shown in FIG. 4, the compensating liquid 2 is put in the container 1, the artificial dental root is inverted and inserted therein, and the adhesive 4 is held so that the portion 4 in contact with the outside exists in the compensating liquid 2. It is preferred to initiate polymerization of the adhesive. In FIG. 1, 5 is an artificial tooth root main body and 6 is a metal core. By using the adhesive and the compensating liquid as described above, the bonded artificial tooth root is cured earlier in the adhesive layer when the polymerization starts, and simultaneously contracts. The negative pressure due to this contraction serves as a driving force, and the compensating liquid is sucked up from the outside into the generated voids to be replenished. Then, by raising the polymerization temperature, the compensating liquid portion can be completely polymerized and cured. For complete polymerization, the polymerization temperature must be 80 ° C or higher, preferably 90 ° C or higher.

Further, in order to completely inject the compensating liquid, it is preferable to apply pressure during the polymerization. The pressurizing method is not particularly limited and various methods can be adopted, including a method of increasing the internal pressure in the polymerization container and a method of utilizing centrifugal force. This pressure is preferably 1 atm or more under atmospheric pressure, and more preferably 1.5 atm or more. Further, the polymerization atmosphere is preferably an inert atmosphere such as a nitrogen gas atmosphere in order to effectively use the polymerization initiator.

[0016]

EXAMPLES Next, the present invention will be described more specifically based on examples, but the present invention is not limited thereto. In the examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 A methyl methacrylate adhesive having the following composition was prepared. Methyl methacrylate monomer 50 parts Polymethyl methacrylate 25 parts Benzoyl peroxide 0.25 part 4-META 1.5 parts Hydroxyapatite powder 125 parts The hydroxyapatite powder used is after granulating a slurry synthesized by a known method. It was obtained by heat treatment at 1050 ° C. for 4 hours and crushing in a mortar.

Next, a compensating solution was prepared with the following weight composition. Methyl methacrylate monomer 50 parts 4-META 1.5 parts Benzoyl peroxide 0.15 parts

A cylindrical body (having a bottom surface) which serves as an artificial tooth root body
Was made of a hydroxyapatite sintered body, and the core was made of metallic titanium. The above-mentioned methyl methacrylate-based adhesive was filled into the inside of the cylinder, and then the metal titanium core was press-fitted, and then the excess adhesive was removed. As shown in FIG. 1, the composite artificial tooth root is inserted into a container containing a compensating liquid, and in this state, put into a pressure cooker to carry out pressure polymerization under a nitrogen atmosphere of 2 atm to polymerize the adhesive. Polymerization was performed while compensating for voids caused by shrinkage with a compensating liquid. Polymerization
It starts when the temperature is maintained at 50 ° C for 13 hours, then the temperature is raised stepwise, and finally after maintaining at 95 ° C for 1 hour,
Polymerization was terminated by slow cooling. Then, the excess solidification compensation liquid outside the tooth root was removed. The longitudinal compressive strength and the transverse compressive strength of the obtained artificial tooth root sample were measured by the following methods, and the results are shown in Table 1. The longitudinal compressive strength is indicated by the load when the artificial tooth root is erected in a vertical direction with a load applied from above and below, and the lateral compressive strength is the vertical direction when the artificial root is laid sideways. The load at break is shown.

Example 2 Although the same adhesive composition, compensating solution composition and temperature conditions as in Example 1 were used, an adhesive operation was carried out at normal pressure, and the longitudinal compressive strength and transverse compressive strength were measured. The results are shown in Table 1.

Example 3 A methyl methacrylate adhesive having the following composition was prepared. Methyl methacrylate monomer 50 parts Polymethyl methacrylate 50 parts Benzoyl peroxide 0.25 part 4-META 1.5 parts Using the methyl methacrylate adhesive and the compensating liquid having the same composition as in Example 1, Example 1 was used. An artificial tooth root was manufactured in the same manner as above, and the longitudinal compressive strength and the transverse compressive strength thereof were measured.
The results are shown in Table 1.

Comparative Example 1 A bis-GMA adhesive having the following composition was prepared. bis-GMA 60 parts Triethylene glycol dimethacrylate 40 parts 4-META 3 parts Benzoyl peroxide 1 part Hydroxyapatite powder 200 parts The same cylinder and core as used in Example 1 were used, and the above was used inside the cylinder. After filling the bis-GMA-based adhesive and then press-fitting the metallic titanium core, the excess adhesive was removed, the temperature was maintained at 50 ° C for 10 hours at normal pressure, and then the temperature was raised stepwise. Finally, polymerization was carried out by maintaining the temperature at 110 ° C. for 1 hour. The longitudinal compressive strength and the transverse compressive strength of the obtained artificial tooth root sample were measured, and the results are shown in Table 1.

[0023]

[Table 1]

From these results, it is understood that according to the present invention, both the longitudinal compressive strength and the transverse compressive strength are remarkably improved as compared with the conventional product, and the effect is further improved by the pressure polymerization.

[0025]

According to the method of the present invention, an artificial tooth root having high strength can be obtained without generating voids due to polymerization shrinkage.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a suitable polymerization step in the method of the present invention.

[Explanation of symbols]

1 container 2 compensation liquid 3 adhesive 4 The part where the adhesive contacts the outside world 5 Artificial tooth root body 6 metal core

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-348748 (JP, A) JP-A-3-292947 (JP, A) JP-A-63-160666 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) A61C 8/00 A61K 6/04 A61K 6/08

Claims (6)

(57) [Claims] 1. A method for producing an artificial tooth root, which comprises placing an adhesive agent in a concave portion of an artificial tooth root body made of a ceramics sintered body, and then inserting and joining a metal core body, which is caused by polymerization shrinkage of the adhesive agent. A method for producing an artificial dental root, which comprises injecting a compensating liquid containing a polymerizable unsaturated compound and a polymerization initiator into the voids. 2. The method for producing an artificial tooth root according to claim 1, wherein the adhesive agent is an adhesive agent to which the same kind of ceramic powder as that constituting the artificial tooth root body is added as a filler. 3. The method for producing an artificial dental root according to claim 1, wherein the polymerizable unsaturated compound is the same as the monomer component in the adhesive used. 4. The method for producing an artificial dental root according to claim 1, wherein the adhesive is a methacrylate adhesive and the unsaturated compound in the compensation liquid is a methacrylic acid ester. 5. The method for producing an artificial tooth root according to claim 1, wherein the polymerization is carried out under pressure in an inert atmosphere. 6. The method for producing an artificial dental root according to claim 1, wherein the ceramic sintered body has a hydroxyapatite and / or tricalcium phosphate layer on at least the outer surface thereof.