JPH0999053A - Surface reforming method for implant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the joinability of a metallic implant material to the gingival epithelium and the adaptability thereof to the muscular tissues by subjecting a core material surface to surface polishing, then to a water heat treatment with an aq. soln. contg. phosphate ions and calcium ions. SOLUTION: This surface reforming method for the implant is executed by subjecting the core material surface to surface polishing, then to the water heat treatment with the aq. soln. contg. the phosphate ions and the calcium ions. As a result, microprojections are removed and microdeposits are washed, by which the phagocytosis by inflammatory cells, macrophage and foreign matter giant cells is suppressed. The information of the stable oxidized films on the surface is accelerated and the elution of metal ions is suppressed by keeping the implant immersed for a long period of time in water under heating. Further, the phosphate ions and the calcium ions are added into the water, by which these ions are taken into the passive films at the time of forming these films on the metallic surfaces by the water heat treatment or the formation of the layer ample in the calcium phosphate on the surface is accelerated and the bio-compatibility is enhanced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for modifying the surface of an implant.

[0002]

2. Description of the Related Art Currently, many metal implants such as artificial joints and artificial tooth roots are clinically used in the fields of medicine and dentistry. However, due to the elution of metal ions, sufficient compatibility with living tissues is obtained. The current situation is not. Even in 316L stainless steel, which is a corrosion resistant material, the elution of a trace amount of Ni has been confirmed. Since pure titanium forms a stable oxide film on the surface and works as a passive film with high corrosion resistance, it is considered that there is almost no ion elution and the tissue reaction is good. However, there are still many unclear points regarding the reaction at the interface with cells, such as the case where the titanium plate was phagocytosed or pitted by cells in cell culture.Therefore, it is necessary to further enhance affinity at the cell level for titanium. Is believed to be. So far
Various surface modifications have been attempted for the purpose of enhancing the tissue compatibility of biomedical metal materials. In addition, a method of thickening the oxide film by heating or performing anodic oxidation has been attempted in order to prevent the elution of ions from the material, but the oxide film tends to thicken, causing material deterioration such as peeling and crystallization of the base material. I am worried about being connected. In addition, there are attempts to increase the strength and tissue affinity of titanium-based materials by performing nitriding treatment, but although the strength is increased, the tissue reaction of nitride is considered to be rather inferior to that of oxides. On the other hand, it has been clarified that hydroxyapatite ceramics have an affinity for soft tissues and mucous membranes such as skin tissues and gingival epithelium tissues, and percutaneous terminals, artificial tooth roots, artificial blood vessels, artificial trachea, etc. have been put into practical use. Or is being done. However, the strength of hydroxyapatite is not sufficient, and its application to the site where mechanical stress is applied is limited. Therefore, various studies have been conducted on compounding with metal materials, but most of them have been aimed at application to bone tissue, and did not consider affinity for soft tissue. Particularly, since the artificial tooth root is partially exposed in the oral cavity, in order to prevent bacterial infection from the oral cavity, it is essential that the affinity and epithelial adhesion with the gingival epithelial tissue are extremely good, In reality, few materials satisfy this condition or effective manufacturing methods.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an effective and simple surface modification method for increasing the bondability of a metallic implant material with gingival epithelium and compatibility with soft tissues such as muscle tissue. is there.

[0004]

In view of the above, as a result of intensive studies, the inventors devised the most effective and simple method for achieving the affinity for soft tissues and the infection resistance, and arrived at the present invention. That is, it is a method of chemically obtaining good surface properties by performing so-called hydrothermal treatment, which is performed by mirror-polishing and then immersing in water and performing heat treatment under high temperature and high pressure. As a result, (1) removal of fine protrusions and washing of minute deposits have the effect of suppressing phagocytosis by inflammatory cells, macrophages, and foreign body giant cells. (2) Elution of trace elution ions By cleaning the surface, it has the effect of suppressing the reaction to cells,
(3) Immersion in water for a long time under heating promotes the formation of a stable oxide film on the surface, suppresses the elution of metal ions, and has an affinity for cells and tissues due to hydrogen bonding reaction in vivo. (4) has the effect of partially converting the oxide in the film into hydroxide in a hydrothermal environment, and has the effect of increasing the affinity for cells and tissues. (5) Furthermore, in water By adding phosphate ions and calcium ions, these ions are incorporated into the film during the formation of a passive film on the metal surface by hydrothermal treatment, or by promoting the formation of a calcium phosphate-rich layer on the surface, It is very effective and highly effective in increasing the biocompatibility of metal materials for living organisms with respect to cells and soft tissues and obtaining infection resistance. A stool surface modification method.

The composition of the implant surface modification method of the present invention, the mode of use, etc. will be described in detail below.

The hydrothermal treatment in the present invention means a heat treatment under a high pressure in an aqueous atmosphere, and the temperature is 90 ° C. or higher, preferably 110 to 130 ° C., 0.1 to 0.2 MP.
It is treated for 1 to 200 hours while being immersed in water under the pressure of a. The effect of the present invention is further amplified by subjecting the surface of the metal material to mirror-polishing using mechanical polishing such as polishing paper or buff, chemical polishing, electrolytic polishing, etc., and then performing hydrothermal treatment. The phosphate ion coexisting in water is represented by PO ₄ , and in addition to calcium phosphate compounds such as hydroxyapatite, tricalcium phosphate, tetracalcium phosphate, and calcium hydrogenphosphate, sodium dihydrogenphosphate and dihydrogenphosphate are included. Examples thereof include sodium, dipotassium hydrogen phosphate, ammonium phosphate and the like. Calcium ions, in addition to the calcium phosphate compound,
Examples thereof include calcium carbonate, calcium chloride, calcium nitrate, calcium hydroxide and the like. Further, considering the corrosion resistance and chemical stability of the metal, Mg, Sr, Fe,
It also includes those to which various ions such as Cr, Ti, Zr, Co, Mo, Al, Si, V and F are added.

[0007]

The present invention will be described below in detail with reference to examples. (Example 1) Pure titanium was buffed and then chemically polished to obtain a mirror surface. This was thoroughly ultrasonically washed in acetone and dried, then immersed in a tricalcium phosphate suspension in a Teflon container, and each container was placed in an autoclave. After reacting at 110 ° C. for 40 hours and then taken out and subjected to elemental analysis using an Auger electron surface analyzer, the presence of phosphorus and calcium was found on the surface of the oxide film.

Example 2 A pure titanium implant having a diameter of 4 mm and a length of 20 mm and having a screw shape of 10 mm from one end was prepared. After buffing the non-screwed portion, chemical polishing was further performed to obtain a mirror surface. This was thoroughly ultrasonically washed in acetone and dried, then immersed in a suspension of amorphous calcium phosphate in a Teflon container, and each container was placed in an autoclave. 4 at 120 ° C
After reacting for 0 hour, it was taken out, only the screw part was embedded in the canine bone of the dog, and the gingival epithelium was sutured. The bondability with the gingiva was extremely good. Even after 6 months, redness, bleeding, pain, swelling, and gingival recession were observed. No obvious infection or inflammation such as pockets, bone resorption, etc. was observed. On the other hand, the untreated control had bleeding after 3 months and pockets were observed.

(Example 3) Regarding the titanium plate obtained by the treatment of (1), the titanium plate just polished (untreated) and the control (excluding the plate), under the conditions described in (2) and thereafter. The state of cell adhesion was measured by. (1) About 300 ml of deionized water and α
-I added about 2g of TCP. A JIS II type titanium plate (12.5 x 12.5 mm), which was mirror-polished on one side, was left still in this closed container with the polishing surface facing upward. At this time, it was placed so that α-TCP did not ride on the titanium surface. Hydrothermal conversion treatment was carried out by placing this sample bottle in a thermostatic chamber controlled at 120 ° C for 20 hours. After a predetermined time, the sample was taken out and the surface was wiped off and dried in the atmosphere. Then, the sample was enclosed in a sterilized pack, sterilized in an autoclave at 120 ° C. for about 30 minutes, and then dried. (2) Cell: NB1RGB cell (human neonatal skin fibroblast, RIKEN cell bank) Medium: RITC80-7 (Kyokuto Pharmaceutical Co., Ltd.) + 10% FCS (IRVINE S
CIENTIFIC) Culture area 3.8 cm ² 12 well Micro Plate, or 2.0 cm ²
Use 24 well Micro Plate. The above sample (titanium plate (12.5 × 12.5 mm)) was placed on a Micro Plate with the polished surface facing upward, and 2 × 10 ⁵ NB1 RGB cells were cultured (37 ° C., 5% CO ₂ (incubator)). The amount of genomic DNA of the cells adhered to the sample plate 3 and 6 hours after the start of culture was determined by DNA fragmentat
Ion ELISA Kit (Boehringer-Mannheim) absorption wavelength 45
Measured using 0 nm. In addition, the number of cells was determined from a calibration curve obtained from the number of cells and the amount of DNA. The results are shown in Table 1.

[Table 1] FIG. 1 shows the absorbance, and FIG. 2 shows the comparison of the number of cells adhered to one surface of the sample titanium plate. 3 after starting the test
It is a result about time and 6 hours. In the figure, Ti Plate is an untreated titanium plate, Coated Ti plate is
The values are shown for cells adhered to the titanium plate treated with (1). Furthermore, the cell adhesion surface was photographed with a scanning electron microscope. The results are shown in FIGS. 3 and 4. Figure 3 shows a culture area of 2 cm ² and a 24-well Micro Plate with 5 x
Place a 5 mm titanium plate and culture 1 × 10 ⁵ cells.
The photograph after time is shown. Figure 4 also shows 24 well Micro Pl
The same titanium plate was placed on the ate to culture 1 × 10 ⁴ cells, and the photograph after 2 days is shown. In each figure, (a) is an untreated titanium plate, and (b) is the plate surface that has been subjected to the treatment of (1) above. From the above results, it was confirmed that the cell adhesiveness was increased by polishing the titanium plate and then hydrothermally treating it in a phosphate ion and calcium ion atmosphere.

[0010]

As described above in detail, the present invention has an effect that an implant made of a metallic material for living body can be improved in biocompatibility with cells and soft tissues by a simple method to obtain infection resistance. .

[Brief description of drawings]

[Figure 1]

FIG. 2 is a diagram for explaining the present invention.

FIG. 3

FIG. 4 is a photograph diagram for explaining the present invention.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 9, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is an absorbance-time graph chart for explaining the present invention.

FIG. 2 is a cell number-time graph for explaining the present invention.

FIG. 3 is a SEM photograph of a cell adhesion surface of an object which has not been treated according to the present invention.

FIG. 4 is a SEM photograph of a cell adhesion surface of an object subjected to the treatment of the present invention.

Claims (1)

[Claims] 1. A method for modifying the surface of an implant, which comprises performing mirror-polishing on the surface of a core material and then performing hydrothermal treatment with an aqueous solution containing phosphate ions and calcium ions.