Patent Application
20060222678
1. Field of the invention
The present invention relates to a biocompatible implant coated with a biocompatible fluor-hydroxyapatite and a coating method of the same, and in particular to a method for coating a hydroxyapatite(HA) and a fluor-hydroxyapatite on a biocompatible implant titanium(Ti) metal substrate having an excellent biocompatibility and mechanical property and a biocompatible implant coated based on the above method.
2. Description of Related Art
A human body may corrode a certain metal therein. A biocompatibility implant titanium(Ti) is widely used as a biocompatible material for an implant in a dental field as well as an orthopedic surgery based on its excellent biocompatibility which is nearest an environment of a bone of a human body, an excellent mechanical property, and a no-harm to a human body in a reaction with a biocompatible tissue.
Recently, there are many attempts for physically and chemically improving a surface property of the same for enhancing an osseointegration. Among the above attempts, a process for coating an apatite is generally used. A hydroxyapatite which is used as a coating layer has a very similar crystal and chemical characteristic with respect to a hard tissue such as a bone, tooth, etc. of a human body. Therefore, when it is implanted into a living body, it does not make any trouble with a biocompatible tissue and a harmful reaction and has an excellent compatibility with a surrounding tissue.
The chemical formula of an apatite which is a ceramic coating layer for a biocompatible implant of the present invention may be expressed as follows in the formula (1).
Ca10(PO4)6Z2 (1)
Where Z represents OH, F, Cl or a compound of the same. The apatite consisted of OH and F mainly exists in the nature. OH represents hydroxyapatite, and F represents fluorapatite. There is a difference in a chemical stability.
Generally, it is known that a fluorapatite has a better chemical stability compared to a hydroxyapatite. In addition, the fluorapatite and hydroxyapatite are known to form a solid solution in the whole range based on an inter-substitution of operation groups OH and F for thereby forming a fluor-hydroxyapatite. As the amount of substitution of fluorine is increased, a chemical safety is enhanced.
In particular, in a dental medical field, there are many reports concerning the effect of fluorine ion itself. When it is used as a repairing structure material of teeth, an addition of a fluorine ion is directed to removing tartar and to enhancing a crystalline and plays an important role for forming a bone.
A certain effort is proceeded for substituting a damaged tooth or bone in a human body tissue using a biocompatibility and bioactivation of apatite. However, the apatite is known to have a disadvantage that a mechanical strength and fracture toughness are bad. Therefore, the apatite is not good as a hard tissue material of a human body which requires a high mechanical strength and fracture toughness such as an artificial dental implant or hip joint. The apatite is limitedly used for a portion which does not need a mechanical strength such as a bone in an inner ear.
In order to overcome the above described mechanical problems of the apatite, there are many attempts for coating an apatite on a metal or ceramic which has an excellent mechanical property as a coating layer. However, among the methods which are most widely used, a TPS(Titanium Plasma Spray) method is used. However, since this method is implemented at a very high temperature (6,000˜15,000° C.), the phase of the apatite is easily decomposed, so that it is impossible to obtain a pure and uniform composition. In addition, it is impossible to enhance an adhering strength with a titanium substrate by forming a thin coating layer of 50˜200 μm. Therefore, an exfoliation occurs in an interface with respect to a titanium substrate, and a roughness of surface is high. Therefore, there is a negative effect in a formation in grooves.
In addition, according to a result of the research, it is known that as the roughness of the surface is increased, an osseointegration is increased. Therefore, as a means for increasing a surface roughness, a sandblasting method is used. A blasting method in which a titania is used as a medium is most widely used.
Since a desired roughness is not achieved based on only a blasting method in which a titania is used, a method using Al2O3 is developed. However, the method using alumina has an advantage in increasing the roughness of surface, but it is not obviously known whether the alumina existing in the surface of an implant affects a human biocompatible or not. Therefore, the above method is not actually used for a clinical purpose.
In addition, an acid etching method is used. Since the method does not achieve a desired roughness of a surface based on only an acid etching process, it is preferred that the above method is used together with the blasting method. However, in this case, the process is complicated.
Accordingly, it is an object of the present invention to provide a biocompatible implant coated with a fluor-hydroxyapatite for a biocompatible and a coating method of the same.
It is another object of the present invention to provide a method for coating a hydroxyapatite(HA) and a fluor-hydroxyapatite on a biocompatible implant titanium metal substrate having an excellent biocompatibility and a mechanical property.
In the present invention, an apatite sol is prepared using a sol-gel method for obtaining a good quality coating film according to the present invention.
To achieve the above objects, in a surface processing method of an implant for a biocompatible, there is provided a fluor-hydroxyapatite coating method for a biocompatible implant which includes a step for preparing a hydroxyapatite sol, a step for preparing a fluor-hydroxyapatite sol, a step for coating the hydroxyapatite sol and fluor-hydroxyapatite sol on a titanium implant, and a step for heat-treating a titanium substrate for a biocompatible implant coated with a titania.
The preferred embodiments of a titanium surface processing method for a biocompatible implant according to the present invention will be described with reference to the accompanying drawings.
The examples of the present invention will be described in detail.
The step for fabricating a hydroxyapatite sol includes a step in which Ca(NO3)2.4H2O which is a material of a calcium are dissolved in an ethanol C2H5OH and are agitated for thereby preparing a calcium solution, a step in which P(CH3CH2O)3 which is a material of a phosphorus and a distilled water(H2O) are dissolved in an ethanol C2H5OH and are agitated for thereby preparing a phosphorus solution, a step in which a calcium solution and a phosphorus solution are mixed and agitated, and a step in which the above solution are aged.
The calcium solution and phosphorus solution are characterized in that calcium and phosphorus are mixed at a mol ratio of 1.67. The above mixture is aged at a room temperature for 60 hours through 80 hours and then is aged again at a temperature of 35° C. through 45° C. for 20 hours through 30 hours.
The step for preparing a fluor-hydroxyapatite sol includes a step in which Ca(NO3)2.4H2O which is a material of a calcium are dissolved in an ethanol C2H5OH and are agitated for thereby preparing a calcium solution, a step in which P(CH3CH2O)3 which is a material of a phosphorus and a distilled water(H2O) are dissolved in an ethanol C2H5OH and are agitated for thereby preparing a phosphorus solution, a step in which NH4F is added into the phosphorus solution, a step in which the calcium solution and phosphorus solution are mixed and agitated, and a step in which the above solution is aged.
The step in which NH4F is added is characterized in that the ratio with respect to F− and OH− is 25 mol %, 50 mol % and 75 mol %.
The step for coating an apatite sol on a titanium substrate includes a step in which an apatite sol is applied to a biocompatible implant titanium substrate for thereby wetting the titanium substrate, a step in which a spin coating process is performed using a spin coating unit, a step in which the titanium substrate coated with an apatite sol is dried, and a step in which the titanium substrate is heat-treated.
The spin coating process is performed in such a manner that a spinning operation is performed for 10 seconds through 30 seconds at 2,500 through 3,500 rpm. The above heat treatment is performed for 1 through 2 hours at 400° C. through 600° C.
As described above, in the present invention, it is possible to enhance a biocompatibility by coating an apatite on a biocompatible implant titanium for thereby implementing a good osseointegration.
In addition, since the apatite coating uses a sol gel method, it is possible to simplify a process and to implement a thin and uniform film.
The sol gel apatite coating method is capable of implementing a uniform thin film coating on a surface of a dental root shaped implant of a complicated shape through a spin coating. Therefore, the present invention is well adapted to a coating process of other biocompatible implants having a complicated shape.
In addition, the fluor-hydroxyapatite and hydroxyapatite coating later according to the present invention has a certain difference in the solution speed, so that it is possible to effectively control a biocompatible activation of an implant. It is possible to implement a functional gradient coating in which a biocompatible activation has a uniform difference by fabricating a hydroxyapatite as an outer later and a fluor-hydroxyapatite layer as an inner layer.
It is possible to implement a beneficial biocompatible characteristic that a fluorine ion has in such a manner that a fluorine ion is contained in a biocompatible implant surface.
It is expected that the demand of a biocompatible implant fabricated according to the present invention will be increased, and an enough supply may be implemented based on its mass production characteristic.
As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described examples are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2003-0032134 | May 2003 | KR | national |
| 10-2003-0032165 | May 2003 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR03/01489 | 7/24/2003 | WO | 11/10/2005 |
