JP4365833B2 - Method for manufacturing dental implant and method for manufacturing dental implant - Google Patents

Description

The present invention relates to a dental implant and a manufacturing method thereof The surface-modified.

  Currently, many metal implants such as artificial joints and artificial tooth roots are used clinically in the medical and dentistry fields, but due to the elution of metal ions, sufficient compatibility with living tissue is not obtained. It is. Even in 316L stainless steel, which is regarded as a corrosion-resistant material, elution of a trace amount of Ni has been confirmed. Pure titanium forms a stable oxide film on the surface and works as a passive film having high corrosion resistance. Therefore, there is almost no elution of ions and the tissue reaction is considered good. However, there are still many unclear points about the reaction at the interface with the cells, such as cases where the titanium plate was phagocytosed or pitted by cells in cell culture, and it is necessary to further increase the affinity at the cell level for titanium. There are thought to be.

Up to now, various surface modifications have been attempted for the purpose of enhancing the tissue compatibility of the biomaterial. In addition, in order to prevent ion elution from the material, an attempt has been made to increase the thickness of the oxide film by heating or anodizing. There is a worry about being connected. Titanium-based materials have been tried to increase strength and tissue affinity by performing nitriding treatment, but although the strength is increased, the structure reaction of nitride is considered to be inferior to that of oxide. On the other hand, it has become clear that ceramics of hydroxyapatite have an affinity for soft tissues and mucous membranes such as skin tissue and gingival epithelial tissue, and percutaneous terminals, artificial tooth roots, artificial blood vessels, artificial trachea, etc. have been put into practical use, Or is being done.
JP-A-4-371146 JP-A-5-57011

  However, hydroxyapatite is not sufficient in strength, and there is a limit to application to a site where mechanical stress is applied. Therefore, various studies have been made on the compounding with metal materials, but most of them were intended for application to bone tissue, and did not consider the affinity to soft tissue. In particular, since the artificial tooth root is partially exposed in the oral cavity, in order to prevent bacterial infection from the oral cavity, it is indispensable that the affinity with the gingival epithelial tissue and the epithelial adhesion are very good. In reality, there are few materials or effective production methods that satisfy this condition.

  An object of the present invention is to provide an effective and simple surface modification method for enhancing the bondability of a metal implant material to a gingival epithelium and the adaptability to soft tissues such as muscle tissue.

In view of the above, as a result of extensive studies, the inventors have found the most effective and simple method for achieving affinity for soft tissue and infection resistance, and have reached the present invention.
That is, the present invention relates to a method for obtaining chemically good surface properties by performing so-called hydrothermal treatment in which mirror polishing is performed, followed by immersion in water and heat treatment under high temperature and high pressure. As a result, (1) by removing minute protrusions and washing minute deposits, the effect of suppressing phagocytosis by inflammatory cells, macrophages and foreign body giant cells is effective. (2) Elution of trace eluting ions By cleaning the surface, there is an effect of suppressing reaction to cells.

(3) By immersing in water for a long time under heating, it 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 by hydrogen bonding in vivo. (4) has the effect of changing part of the oxide in the film to hydroxide in a hydrothermal environment, and has the effect of increasing the affinity for cells and tissues; (5) 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 the formation of a layer rich in calcium phosphate on the surface is promoted. It can be expected to have an effect of increasing affinity, and it is extremely effective in increasing the biocompatibility of biomaterials for cells and soft tissues and obtaining infection resistance. A stool surface modification method.

Hereinafter, the implant surface modification method of the present invention will be described in detail with respect to the composition, use mode, and the like.
The hydrothermal treatment in the present invention means that the heat treatment is performed under high pressure in an aqueous atmosphere, and is immersed in water at a temperature of 90 ° C. or higher, preferably 110 to 130 ° C. and 0.1 to 0.2 MPa. Process for 1 to 200 hours in the state. The effect of the present invention is further amplified by performing a hydrothermal treatment on the surface of the metal material in advance using mirror polishing using a method such as mechanical polishing with abrasive paper or buff, chemical polishing, or electrolytic polishing. The phosphate ion that coexists in water is represented by PO4, and in addition to calcium phosphate compounds such as hydroxyapatite, tricalcium phosphate, tetracalcium phosphate, and calcium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate Examples thereof include dipotassium hydrogen phosphate and ammonium phosphate. Examples of calcium ions include calcium carbonate, calcium chloride, calcium nitrate, and calcium hydroxide in addition to the calcium phosphate compound. In addition, in consideration of metal corrosion resistance, chemical stability, etc., those containing various ions such as Mg, Sr, Fe, Cr, Ti, Zr, Co, Mo, Al, Si, V, and F are also included. To do.

  As described above, the present invention has effects such as improving the biocompatibility to cells and soft tissues and obtaining infection resistance with a simple method for implants made of metal materials for living organisms.

  In the present invention, a hydrothermal treatment portion is formed on a polished surface where at least a contact surface between a living soft tissue and a metal core material has removed fine protrusions on the surface of the core material.

  Hereinafter, the present invention will be described specifically by way of examples. Example 1 Pure titanium was buffed and then chemically polished to give a mirror surface. This was sufficiently ultrasonically washed in acetone and dried, then immersed in a tricalcium phosphate suspension in a Teflon (registered trademark) container, and the entire container was placed in an autoclave. After reacting at 110 ° C. for 40 hours, the sample was taken out and subjected to elemental analysis using an Auger electronic surface analyzer. As a result, the presence of phosphorus and calcium was observed on the oxide film surface.

  A pure titanium implant having a screw shape of 10 mm from one end of a diameter of 4 mm and a length of 20 mm was prepared. After buffing the part without screws, chemical polishing was further performed to obtain a mirror surface. This was thoroughly ultrasonically washed in acetone and dried, and then immersed in an amorphous calcium phosphate suspension placed in a Teflon (registered trademark) container, and the entire container was placed in an autoclave. After reacting at 120 ° C. for 40 hours and taking out, only the screw part was inserted into the canine jawbone and the gingival epithelium was sutured. There was no obvious infection or inflammation such as gingival recession, pockets, and bone resorption. On the other hand, the untreated control was bleeding after 3 months and pockets were observed.

Cell adhesion under the conditions described below (2) and below for titanium plates obtained by treatment (1) below, just polished titanium plates (untreated) and controls (not including plates) The state was measured.
(1) About 300 ml of ion-exchanged water and about 2 g of α-TCP were put into a pressure-resistant bottle that can be sealed. In this sealed container, a JIS II type titanium plate (12.5 × 12.5 mm), which was mirror-polished on one side, was allowed to stand with the polishing surface facing up. At this time, α-TCP was arranged so as not to get on the titanium surface. The sample bottle was placed in a thermostat controlled at 120 ° C. for 20 hours for hydrothermal conversion treatment. After a predetermined time, the sample was taken out and the surface was wiped off and dried in the atmosphere. The sample was enclosed in a sterilization pack, sterilized in an autoclave at 120 ° C. for about 30 minutes, and then dried.
(2) Cells: NB1RGB cell (human newborn skin fibroblasts, RIKEN cell bank) Medium: RITC80-7 (manufactured by Kyokuto Pharmaceutical) + 10% FCS (manufactured by IRVINE SCIENTIFIC) Culture area 3.8 cm ² 12 well Micro Plate, Alternatively, use a 2.0 cm ² 24 well Micro Plate. The above sample (titanium plate (12.5 × 12.5 mm)) was placed on a microplate with the polished surface facing up, and 2 × 10 5 NB1RGB cells were cultured (37 ° C., 5% CO ₂ (incubator)). The genomic DNA amount of the cells adhering to the sample plate was measured 3 and 6 hours after the start of culture using a DNA fragmentation ELISA Kit (manufactured by Boehringer-Mannheim) using an absorption wavelength of 450 nm. 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.

FIG. 1 shows a comparison of absorbance, and FIG. 2 shows a comparison of the number of cells adhered to one surface of a sample titanium plate. All are the results for 3 hours and 6 hours after the start of the test. In the figure, Ti Plate is an untreated titanium plate, and Coated Ti plate is a value for cells adhered to the titanium plate treated in (1). Furthermore, the cell adhesion surface was photographed with a scanning electron microscope. The results are shown in FIGS. 3 and 4 show photographs after 6 hours of culturing 1 × 10 ⁵ cells by placing a 5 × 5 mm titanium plate on a culture area of 2 cm ² and a 24-well microplate. FIG. 5 and FIG. 6 show photographs after 2 days after the same titanium plate was placed on a 24-well microplate and 1 × 10 ⁴ cells were cultured.
In each figure, FIGS. 3 and 5 are untreated titanium plates, and FIGS. 4 and 6 are plate surfaces subjected to the treatment (1). From the above results, it was confirmed that after the titanium plate was polished, cell adhesion was increased by hydrothermal treatment in a phosphate ion and calcium ion atmosphere.

The light absorbency-time graph figure for demonstrating this invention. The cell number-time graph figure for demonstrating this invention. The SEM photograph for demonstrating the comparative example with respect to the Example of this invention. The SEM photograph for demonstrating the Example of this invention. The SEM photograph for demonstrating the comparative example with respect to the Example of this invention. The SEM photograph for demonstrating the Example of this invention.

Claims (10)

A dental implant in which a hydrothermal treatment portion is formed on a polished surface from which at least a contact surface between a living soft tissue and a metal core material has removed fine protrusions on the surface of the core material. A method for producing a dental implant, characterized in that at least a contact surface between a living soft tissue and a metal core material is polished to remove fine protrusions on a metal surface and then subjected to hydrothermal treatment. The dental implant according to claim 1, wherein a polishing surface is formed on the surface of the metal core by two different polishing means. The method for producing a dental implant according to claim 2, wherein the metal core surface is polished twice by different polishing means. The dental implant according to claim 3 , wherein the polishing means is selected from mechanical polishing, chemical polishing, and electrolytic polishing. The method for producing a dental implant according to claim 4, wherein the polishing means is selected from mechanical polishing, chemical polishing, and electrolytic polishing. The dental implant according to claim 1, wherein the metal is a titanium material. The method for manufacturing a dental implant according to claim 2, wherein the metal is a titanium material. The dental implant according to claim 1, wherein the hydrothermal treatment is performed in an aqueous atmosphere containing phosphate ions and calcium ions. The method for producing a dental implant according to claim 2, wherein the hydrothermal treatment is performed in an aqueous atmosphere containing phosphate ions and calcium ions.

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