JPH0236112B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an implant material intended to substitute for or act as a substitute for bones in various parts of the human body, such as artificial bones, artificial joints, or artificial tooth roots.

[Technological background] With the development of bioengineering, artificial materials shaped like joints or tooth roots are inserted (implanted) into the bone tissue of the human body to restore lost biological functions. Implant surgery for this purpose is in the spotlight.

Conventionally known artificial materials used in this implant procedure include metal materials such as cobalt-chromium alloy, titanium, and tantalum, and ceramic materials such as hydroxyapatite, zirconia, alumina, and glassy carbon. However, although metal materials have excellent mechanical strength, they have poor affinity for living organisms, and some of them are harmful due to elution of metal ions. On the other hand, although ceramic materials have excellent affinity for living organisms, they remain unsatisfactory in terms of mechanical properties.

That is, conventional artificial materials each have advantages and disadvantages in terms of toxicity to living organisms, compatibility with bones, durability, etc., and it is difficult to say that they are necessarily satisfactory implant materials. In order to solve these problems, attempts have been made to combine different materials.

For example, as an implant material in which a metal material and other materials are integrated into a composite, JP-A-53-28997 discloses an implant material in which a sprayed layer of ceramic powder and hydroxyapatite powder is formed on the outer periphery of a metal base material. The above-mentioned implant material is expected to take advantage of both the biocompatible properties of hydroxyapatite and the mechanical properties of the metal base material, but due to the difference in thermal expansion between the metal base material and the sprayed layer material, cracks may occur in the sprayed layer material. There is a concern that metal ions may be leached from the cracks.

In addition, in JP-A-57-156757, the outer surface of a metal base material is made of a thermoplastic polymer such as polysulfone, high-density polyethylene, or polymethyl methacrylate, or by adding 20 to 30% of an inorganic material such as calcium phosphate or hydroxyapatite to them. An implant material coated with a composition is disclosed. However, these thermoplastic polymers are insufficient in adhesion to metal substrates, stability in vivo, osteogenicity, mechanical properties, etc., and cannot be said to be practically reliable.

[Object of the Invention] In view of the above-mentioned circumstances, the present invention aims to provide a practically reliable implant material that is excellent in biocompatibility, biostability, mechanical properties, etc.

[Effects of the Invention] The above object is achieved by the composite integrated implant material according to the present invention, which is formed by forming a layer of thermosetting resin on the outer periphery of a metal base material.

The implant material of the present invention is a composite of a thermosetting resin that has excellent properties as described above and a metal base material, making use of the properties of each, and is practically reliable with excellent biocompatibility, biostability, mechanical properties, etc. It is possible. Furthermore, when the implant material of the present invention is used as an artificial tooth root, it does not cause any discomfort to the living body due to the appropriate elastic modulus and hardness of the thermosetting resin.

[Summary of the Invention] Since the thermosetting resin according to the present invention is implanted in a living body for a long time, it is necessary to have good biocompatibility that does not cause deterioration of the resin or collapse of living cells. Examples include polymers such as bisphenol A-diglycidyl methacrylate, 1,3-butanediol dimethacrylate, ethylene glycol dimethacrylate (1G), diethylene glycol dimethacrylate (2G), and triethylene glycol dimethacrylate (3G). In particular, 3G is preferable because it has advantages such as no harm to living organisms and easy bone formation. The thermosetting resins may be used alone or in a mixture.

The metal base material according to the present invention includes all known metals and alloys, including Co-Cr-Ni alloy, Co-
Dense materials such as Cr-Mo alloy, stainless steel 18-8, 316L, titanium, tantalum, etc., which have extremely little harmful effect on living tissues and have sufficient mechanical strength, have been traditionally used as artificial materials. Alternatively, porous materials are preferred.

The metal base material may be provided with independent and/or continuous grooves on its outer periphery for anchoring effect with the resin composition and dispersion of external force after implantation. The shape and size of the metal base material is not particularly limited, and may include pin type, screw type, blade type, anchor type,
It may be of plate type, mesh type, etc., and its cross section may be square, circular, oval, etc.

Methods for obtaining the implant material of the present invention are not particularly limited, but include, for example, molding, sintering, casting or cutting the metal material, optimally polishing,
Furthermore, the core material obtained by surface treatment as necessary is set in a mold, the resin monomer mixed with a curing agent etc. in advance according to a conventional method is poured, and after curing by heating under normal pressure or pressurization, the resin composition is adjusted as necessary. It can be manufactured by cutting and polishing the surface of an object.

In addition, in the conventional heat curing method, internal strain occurs in the resin layer and cracks are likely to occur at the interface with the core material, so it is necessary to carefully select curing conditions such as temperature and time.

The problem with this conventional thermosetting method is that 5 to 95% by weight, preferably 20 to 80% by weight of thermosetting polymer (polymer) in the form of powder or coarse particles is added to the thermosetting resin (monomer) in advance. This can be solved by adding %. The shape of the added polymer is not particularly limited, and the average particle size is usually about 2 to 500 microns, preferably about 10 to 200 microns.

The outer surface of the resin composition may be smooth or may have an uneven shape such as a screw shape.

Although the application site of the implant material of the present invention is not particularly limited, it goes without saying that it can be used endodontically, intraosseously, subperiosteally, intramucosally, etc.

In addition, when the implant material of the present invention is used as an artificial tooth root, a structure made of hydroxyapatite alone may be disposed around the outer periphery of the resin molded product in a portion located near the inner edge epithelium. Furthermore, the shape of the resin molding in the vicinity of the epithelium may be made into a brim shape to improve epithelial adhesion.

The basic manufacturing method of the implant material of the present invention will be described below.

50g of 3G monomer (Acryester 3ED: manufactured by Mitsubishi Rayon Co., Ltd.) and 50g of 3G polymer with an average particle size of 23μ
was placed in a separable flask, and stirred and degassed at room temperature under vacuum.

Next, 0.5% by weight of a curing agent (t-butyl peroctoate) was added to the flask, and the mixture was stirred and mixed for 30 minutes.

Thereafter, the prepared resin solution was poured into a glass tube with an inner diameter of 4 mm to which a titanium rod with a diameter of 3 mm and a length of 100 mm had been fixed in advance, and was cured under the following conditions.

-Curing conditions- 55℃ (5 hours) -65℃ (2 hours) -70℃ (1 hour) -85℃ (1 hour) -100℃ (1 hour) -110℃
(0.5 hours) -120°C (0.5 hours) The implant material of the present invention is processed into any shape as required and put into practical use.

The accompanying drawings show an embodiment of an artificial tooth root made of the implant material of the present invention. FIG. 1 is a longitudinal cross-sectional view thereof, and FIG. 2 is a cross-sectional view showing its internal structure. That is, for example, the core body 3 of the implant material body 1 is made of titanium or cobalt alloy, and the outer surface of the core body 3 is covered with a triethylene glycol dimethacrylate polymerizable resin layer 2. A screw-shaped groove 4 is provided in the holder.

A standard ready-made artificial tooth crown can be freely selected and adhesively fixed to the upper part of the implant material of the present invention.

This product was inserted into the jawbone of an adult dog, and X-ray observation was performed after 12 months had passed. Good bone formation was observed, and no abnormalities such as inflammation were observed.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the implant material of the present invention;
FIG. 2 is a cross-sectional view. DESCRIPTION OF SYMBOLS 1... Implant material main body, 2... Resin composition part, 3... Metal core, 4... Screw-shaped groove.

Claims (1)

[Claims] 1. An implant material formed by forming a thermosetting resin layer, which is a biocompatible polymer, on the outer periphery of a metal base material. 2. The implant material according to claim 1, wherein the thermosetting resin is a triethylene glycol dimethacrylate polymerizable resin.