Implant having a multilayered coating and a process for preparing thereof

Abstract

The present invention relates to an implant having a multilayered coating comprising a porous titanium-based layer on the implant, an optional interface titania layer on and/or in the porous titanium-based layer and a bioactive glass layer on and/or in the porous structure formed by the titanium-based and titania layer(s); as well as to a process for preparing an implant having a multilayered coating.

Claims

1. An implant comprising a substrate and a multilayered coating, the multilayered coating comprising a porous titanium-based layer on the substrate; a bioactive glass layer in or on and in the porous titanium-based layer and a titania layer between the porous titanium-based layer and the bioactive glass layer, wherein the bioactive glass layer is impregnated in the pores of the porous titanium-based layer or deposited on the porous titanium-based layer and impregnated in the pores of the porous titanium-based layer with the titania layer as a separate layer between the bioactive glass layer and the porous titanium-based layer.

2. The implant according to the claim 1, wherein the titania layer has a thickness of at most 5 m.

3. The implant according to the claim 1, wherein the bioactive glass layer has a thickness of at least 1 m.

4. The implant according to the claim 1, wherein the bioactive glass is applied in the form of a powder suspension and the particle size of the bioactive glass powder is below 10 m and that the bioactive glass is at least partially sintered and that the bioactive glass is prepared by melting, sol-gel, preferably particulate sol-gel method.

5. The implant according to the claim 1, wherein the bioactive glass comprises SiO.sub.2 and CaO and, optionally, one or more oxides selected from Na.sub.2O, K.sub.2O, SrO, ZnO, MgO, B.sub.2O.sub.3, P.sub.2O.sub.5, Ag.sub.2O, or a fluorine containing compound.

6. The implant according to the claim 1, wherein the bioactive glass comprises from 30 to 95 mol % SiO.sub.2 and 0.05 to 40 mol % CaO and, optionally, one or more oxides selected from Na.sub.2O, K.sub.2O, SrO, ZnO, MgO, B.sub.2O.sub.3, P.sub.2O.sub.5, Ag.sub.2O, or a fluorine containing compound.

7. The implant according to the claim 6, wherein the bioactive glass comprises one or more of 0 to 30 mol % Na.sub.2O; 0 to 30 mol. % K.sub.2O; 0 to 30 mol % SrO; 0 to 30 mol % ZnO, 0 to 40 mol % MgO; 0 to 40 mol. % B.sub.2O.sub.3; 0 to 40 mol % P.sub.2O.sub.5; 0 to 5 mol % Ag.sub.2O or any two or more of the preceding.

8. The implant according to the claim 1, wherein the implant comprises one of a permanent implant, a load-bearing implant, or a permanent and load-bearing implant.

Description

EXAMPLE 1

(1) Ti6Al4V implant is vacuum plasma sprayed with a 0.5 mm thick layer of porous titanium with a pore size in the range from 20 to 500 m.

(2) A suspension for TiO.sub.2 coating is prepared from 100 milliliters (ml) of distilled water, 1 gram (g) of titanium powder, 0.5 g of CaF.sub.2 and 0.1 g of SiO.sub.2. Sodium hydroxide, tetra methyl-ammonium hydroxide, phosphoric acid and citric acid are used to adjust pH to 10.

(3) The implant coated with a porous titanium layer is placed in a Teflon vessel, 50% filled with titania suspension. The vessel is put in a steel autoclave, tightly sealed, closed and heated to 200 C. for 48 h. After heating, the system is cooled to a room temperature by self cooling of the furnace. After the container has cooled, the implant is taken out and perfectly cleaned by rinsing with water, repeated sonication in distilled water (10 times for 10 minutes {min}) and sonication in ethanol for 1 h. The implant is then dried in a stream of hot air for 3 h at a temperature of 50 C.

(4) For a bioactive glass with a composition 58 mass % SiO.sub.2-30 mass % CaO-8 mass % P.sub.2O.sub.5-4 mass % ZnO mass % two mixtures M1 and M2 are prepared. For the mixture M1 43 ml TEOS and 2 ml TEP are dissolved in 43.5 ml EtOH. The mixture is stirred for an hour in a sealed container to avoid contact with moisture. For the mixture M2 17 g calcium nitrate tetrahydrate is completely dissolved in distilled water, then 1.45 g of zinc acetate is added and dissolved, then 216 ml of EtOH and then another 43 ml of distilled water is added. The pH of the mixture M2 is carefully adjusted to 11 by addition of amonium hydroxide. The mixture is stirred for an hour. The mixture M1 is then added to M2 drop by drop during stirring and the pH is kept constant between 10 and 11.

(5) After stirring, the suspension is dried at 60 C. The obtained powder is calcined at 600 C. for 2 h. An ethanol suspension of bioactive glass powder for infiltration is dispersed with an ultrasonic finger.

(6) Ti6Al4V with a porous Ti layer and coated with titania is placed in a vessel equipped with two valves. One serves for evacuation and the other for adding the suspension. The vessel has to be tightly sealed. The suspension is pumped into the coating pores. After bioactive glass addition negative pressure is held for another 1 to 2 min. Samples are then dried at room temperature.

(7) The coating is then sintered in a vacuum furnace at a sintering temperature of 875 C. for 2 h, and with a heating rate 5 C./min and self cooling of the furnace.

EXAMPLE 2

(8) Ti6Al4V implant is coated by welded titanium spheres.

(9) Suspension for TiO2 coating is prepared from 100 ml of distilled water, 1 g of titanium oxide powder, 0.5 g of CaF.sub.2 and 0.1 g of SiO.sub.2. Ammonia, tetra methyl-ammonium hydroxide, phosphoric acid and citric acid is used to adjust pH to 10.

(10) The implant is placed in a teflon vessel, 50% filled with titania suspension. Vessel is put in a steel autoclave, tightly sealed, closed and heated to 150 C. for 48 hours. After heating, the system is cooled to a room temperature by self cooling of the furnace. After the container has cooled, the implant is taken out and perfectly cleaned by rinsing with water, repeated sonication in distilled water (10 times for 10 min) and sonication in ethanol for 1 h. The implant is then dried in a stream of hot air for 3 hours at temperature 50 C.

(11) Bioactive glass with a composition 53 mass % SiO.sub.2-20 mass % CaO-4 mass % P.sub.2O.sub.5-23 mass % Na.sub.2O (mass %) is prepared using alkoxide precursor for Na.sub.2O. Two mixtures, M1 and M2 are prepared. For the mixture M1 10 ml TEOS and 0.5 ml TEP are dissolved in 13 ml EtOH. Then 2.56 g of sodium ethoxide dissolved in ethanol is added. The mixture is stirred for an hour in a sealed container to avoid contact with moisture. For the mixture M2 4.28 g of calcium nitrate tetrahydrate is completely dissolved in 5 ml of distilled water and then added to 52 ml of ethanol and 10.5 ml of water. The pH of the mixture M2 is carefully adjusted to 11.3 by addition of ammonium hydroxide. Mixture is stirred for an hour. The M1 is then slowly added to the M2 drop by drop during stirring. The pH value of the mixture M2 is in this case kept constant between 10-11 by sodium ethoxide in the mixture M1, therefore the dropping rate of the mixture M1 is regulated according to the pH of M2.

(12) After stirring the suspension is dried at 60 C. The obtained powder is calcined at 600 C. for 2 h. An ethanol suspension of bioactive glass powder for infiltration is dispersed with an ultrasonic finger.

(13) Ti6Al4V with a porous Ti layer and coated with titania is placed in a vessel equipped with two valves. One serves for the evacuation and the other one for adding the suspension. The vessel has to be tightly sealed. Suspension is pumped into the coating pores. After bioactive glass addition negative pressure is held for another 1-2 min. The sample is then dried at 70 C. The coating is sintered in vacuum furnace at a sintering temperature of 810 C. for 2 h and with heating rate 5 C./min and self cooling of the furnace.

EXAMPLE 3

(14) Ti6Al4V implant is coated by a 0.5 mm thick layer of porous titanium by vacuum plasma spray technique.

(15) For a bioactive glass with a composition 70 mass % SiO.sub.2-30 mass % CaO mass %, 5.76 g of calcium nitrate tetrahydrate completely dissolved in 6 g of distilled water was added to 95.64 g of EtOH with 16.36 g of H.sub.2O. The pH of the mixture was adjusted to 11.3. After half hour of stirring, 12.584 g of TEOS was added. The mixture was heated to 40 C. and stirred for an hour. The pH was controlled with NH.sub.4OH not to drop under 10.

(16) After stirring the suspension is dried at 60 C. The obtained powder is calcined at 600 C. for 2 h.

(17) For infiltration ethanol suspension of bioactive glass powder with 0.2 wt % PEI1800 is prepared. Suspension is dispersed with an ultrasonic finger.

(18) Ti6Al4V with a porous Ti layer and coated with titania is placed in a vessel equipped with two valves. One serves for evacuation and the other for adding the suspension.

(19) The vessel has to be tightly sealed. Suspension is pumped into the coating pores. After bioactive glass addition negative pressure is held for another 1-2 min. The sample is then dried and sintered in vacuum furnace at a sintering temperature 850 C. for 2 h, with heating rate 5 C./min and self cooling of the furnace.

(20) The features disclosed in the foregoing description, in the drawing and in the claims may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.