JPS61141660A - Hot press sintered apatite composite ceramics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to caapatite composite ceramics that are particularly useful as artificial tooth roots and artificial bone materials.

(Background of the Invention) In recent years, research has been actively conducted on implants that include artificial tooth roots and artificial bones. In particular, research is being actively conducted on materials that have excellent affinity and compatibility with bone (hereinafter referred to as biocompatibility), high mechanical strength, and, therefore, provide implants that can be used for a long period of time. One of the representative materials is sintered apatite. Synthetic hydroxyapatite, which is the raw material for sintered apatite, has excellent biocompatibility because it is almost the same as the main constituent of bone minerals. However, when used as an implant material,
As high as possible temperature e.g. 14 to obtain high mechanical strength
It is known that it is necessary to sinter at 00°C, which reduces biocompatibility. It is said that the cause of this may be hydroxyapatite due to removal of hydroxyl groups during sintering, and that oxidized apatite is desirably sintered at 00 to 900°C.

Therefore, if the mechanical strength could be improved by means other than the sintering temperature, it would be necessary to sinter at a high temperature that would reduce biocompatibility, so for the purpose of improving the mechanical strength and sinterability, Synthetic hydroxyapatite powder KCaO1MgO,
It has been proposed to mix additives such as At, O, and other reinforcing materials (Japanese Patent Publication No. 40776/1983).
s lines 37-43).

However, because these additives and reinforcing materials themselves do not have biocompatibility, mixing them with synthetic hydroxyapatite powder will naturally reduce the biocompatibility of the entire furnace body. It's not a fundamental solution.

Therefore, until now, there has been no sintered apatite that has both high biocompatibility and mechanical strength.

The present inventors first discovered that by adding a specific amount of bioactive glass powder to synthetic hydroxyapatite powder and sintering it, this glass acts as a binder and exhibits a sufficiently high mechanical extortion rate even when sintered at a relatively low temperature. Because it is sintered at a low temperature, the structural change to oxidized apatite is suppressed, so there is no decrease in biocompatibility, and because the binder is bioactive glass, which is stronger than just glass, the overall sintered body is It was discovered that the bioadhesion was significantly reduced, and the five-component hydroxyapatite powder Q and the bioactive glass powder (6) were mixed in a weight ratio of A/B = 60/40 to 30/70. A patent application was filed for Apatite Composite Ceramic 2JK, which is characterized by sintering.
No. 9-42474).

(Objective of the Invention) An object of the present invention is to provide an apatite composite ceramic having further improved mechanical strength by improving the invention of the prior application.

(Summary of the invention) The present inventors accidentally discovered that applying pressure during sintering further improves mechanical strength by an average of 30 to 40 factors, and has no significant effect on biocompatibility. Therefore, the present invention provides synthetic hydroxyapatite powder and bioactive glass powder (B) in a weight ratio of 1: A/B.
To provide an apatite composite ceramic, which is characterized in that it is mixed at a ratio of =60/40 to 30/70 and sintered under pressure.

The synthetic hydroxyapatite used in the present invention is natural hydroxyapatite Ca1° (PO,)
, (OH)Y are the same as or similar to them, and are known per se. For example, when Ca ions and phosphate ions are reacted in an aqueous solution, the atomic ratio of Ca/P is 1.5 to 1. ．．
A calcium phosphate precipitate of No. 67 was obtained, and this precipitate was filtered and dried to form a powder, and then calcined at 800°C (cal.
ain・). The powder thus obtained (2
), a suitable particle size is 200 to 500 mesh jL.

On the other hand, bioactive glasses are also known per se as being biocompatible and chemically bonding to bone. - For example, the composition of bioactive glass is as follows (Japanese Patent Application Laid-Open No. 54-17).

Sin, 40-62% by weight Na, 0 10-32% Ca0 10-32% P, 0. 3-9 weight% CaF2 0-18% by weight B20 30-7.5% by weight Since the bioactive glass powder (2) is used as a binder for the powder, it is preferable to use one that melts at a relatively low temperature, particularly 1100°C or lower. The reason for this is that if such a low-melting glass is used, the temperature during sintering can be lowered accordingly, and the risk of structural change from hydroxyapatite to oxidized apatite can be avoided. Examples of such bioactive glasses with low melting properties include those having the following composition.

Sin, 35-60 molti B, 03
5-15 molt NazO 10-30 molt (:, @Q 5-40 molt Tie,
0-10 molti p, o,
o~15 mole, OO~20 mole Lt, OO~10 mole poly Mg0 0~5 mole AtO+ZrO, +Nb, O, O~8-1-le%! 3 LjL*Os + Ta*Os + Y2O5O~8
Powder (G) can be obtained by crushing bioactive glass such as mo/l/%F, O~15 mole or more by a conventional method, but the particle size of powder (B) is generally -20
A value of 0 to 500 mesh 2 is appropriate.

Next, the weight ratio of powder powder and powder ■ is Al6 = 60/4.
Mix in a ratio of 0 to 30/70. The reason why the proportion of Al6 was determined to be within the above range is that, as a result of experiments, it could not be said that the mechanical strength was superior to that of the sintered body of powder (A) alone or powder 03) alone outside this range. .

To sinter the powder (2)/@ mixture, follow the usual method.
After cold-pressing using a mold at a pressure of, for example, 1 to 2 t/-, it may be baked under pressure at a temperature of generally 700 to 1200°C, preferably 750 to 950°C, for generally 10 minutes to 3 hours. The appropriate degree of pressurization is generally 50 to 200 KP/-.

Sintering under pressure is generally called hot press sintering, but preliminary sintering under normal pressure may be performed prior to hot pressing. The contents of the preliminary φ knot are generally 700 to 1200
Calcining at a temperature of preferably 700 to 900°C for 2 to 5 hours is generally sufficient.

Whether hot press sintering or pre-sintering, the firing temperature is 110℃.
If the temperature is raised to 0°C, especially 1200°C, a considerable amount of oxidized xiapatite changes to oxidized xiapatite, so it is dangerous to do so properly.

In the case of hot press sintering, a press mold with high heat resistance, such as a graphite mold, is used. The mold is preferably coated with a mold release agent such as BN powder in advance to prevent the sintered body from being baked.

In hot press sintering, the molten glass powder (2) flows into the fine pores and crevices of the sintered body and fills those spaces, which is thought to improve the mechanical strength of the sintered body. However, changes in biocompatibility are at risk.

The thus obtained sintered body of the present invention, that is, the Anokutite Punposite Ceraelectric Soil, can be used as an -IT implant if the shape and dimensions match, or if it does not match, it can be processed into an implant by appropriately cutting or grinding. In addition, the sintered body of the present invention can be used as a material for screws or screws for temporarily fixing an implant, especially a subperiosteal dental implant, to the dental bone, as well as for a completely different chemical reaction. It can be used as a catalyst, substrate material, etc.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example) (1) Preparation of synthetic hydroxyapatite powder ■0.5
10 tons of a 0.3 mol/L phosphoric acid aqueous solution was added to the mol/l Ca(OH)* suspension ioz, and the mixture was reacted for 1 hour with stirring at a temperature of 20°C. After the reaction, stirring was stopped and the mixture was aged at the same temperature for 48 hours.

After aging, the reaction product was washed with water and passed through the mouth. The hydrated product was instantly dried using a spray drying method and granulated into approximately 100 mesh pieces. When the obtained powder was evaluated by powder X1 diffraction method and chemical analysis method, the ratio of calcium to phosphorus (Ca
/P) is approximately 1.617) with a value of t, no 1 Hydroxia/
It was a microcrystalline calcium phosphate with a structure similar to that of crystalline tite. The calcium phosphate was ground and passed through a 200 Messier sieve to remove coarse particles.

(2) Preparation of bioactive glass powder (B) consisting of 810, 46.1 mol, Nax 024.4 mol, Ca0 13.5 mol, CaFl 13.4 mol% and P, 0.2.6 mol. Powder raw materials are heated and melted in a platinum crucible, clarified, and slowly cooled to produce bioactive glass (
(melting point approximately 1050°C).

This glass was crushed in a conventional manner) and passed through a 500 mesh a sieve to remove coarse particles.

(6) Preparation of sintered body After mixing the powder mixture (1) in the proportions listed in Table 1 below,
A 200f mixture was separated, 200 cc of ethanol was added thereto, and the mixture was mixed for 2 hours using a pot mill.

The mixture was filtered and residual ethanol was evaporated in a dryer at 110°C.

The obtained powder mixture was filled into a metal press mold, and 1.5
Cold pressing was carried out at a pressure of t/cj.

The press molded product was heated at a speed of 200°C/hour in the atmosphere.
The temperature was raised to 00℃, baked at 900℃ for 2 hours, and then heated to 50℃.
The presintered body was cooled at a rate of 0° C./hour and placed in a graphite press mold together with BN powder.

Next, the press mold was heated at 200'C/in a N2 gas atmosphere.
The mixture was heated to 900°C at a rate of 1 hour. At 900℃, 120KP/c was passed through the punch rod to the sample in the mold.
The temperature was maintained at 900° C. for 2 hours while applying a pressure of 110°C. Thereafter, the apatite composite ceramic of the present invention was obtained by cooling to normal m at a rate of 500° C./hour while lowering the pressure at a rate of 60 KP/d-hour.

(Measurement of Mechanical Strength) The four-point bending strength of the prepared sintered body was measured according to JIS: R1601, and the results are shown in Table 1 below.

(Measurement of bone affinity) The prepared sintered body was ground to make a truncated conical prosthesis with a diameter of 2 on the bottom, 5 on the length, and a taper of 1/20, and the piece was implanted in the femur of a rabbit. I planted it. After 8 weeks, the rabbits were sacrificed and the bonding strength between the prosthetic material and the femur was measured by a push out test using a compressive strength tester.9. The results are shown in Table 1 as a measure of biocompatibility.

As a comparative example, powder ① alone was pre-sintered at 1400°C, and the bending strength was as high as 15 Kp/-.
The binding strength in the sh out test was as low as 1.6 P/-, indicating poor biocompatibility.

(Effects of the Invention) As described above, the apatite composite ceramic of the present invention has higher mechanical strength and high bone affinity.

Therefore, in order to maintain the implant with a low bonding force, we created a protrusion to fix the implant with the bone bone by mechanical engagement as in the past. There is no need to use a thick implant.

Therefore, the number of cases to which artificial tooth roots can be applied increases, and the preparation of artificial tooth roots and tooth root implantation surgery become easier.

Not only does this material have the above advantages, but by appropriately changing the composition of the glass powder (B) to be mixed, the expansion coefficient of the sintered body as a whole and the softening temperature of the glass phase can be adjusted appropriately. It is also possible to join the sintered body to the metal core body with an appropriate force by adjusting the force. By doing so, it is possible to further improve the mechanical strength, and the range to which the implant can be applied is expanded.

Claims (1)

[Claims] The weight ratio of synthetic hydroxyapatite powder (A) and bioactive glass powder (B) is A/B = 60/40 to 30/
An apatite composite ceramic characterized by being mixed at a ratio of 70% and sintered under pressure.