RO127411A2 - Biocompatible thin films with compositional gradient for covering metal dental implants - Google Patents

Abstract

The invention relates to materials made up of biocompatible thin layers with compositional gradient used for coating the metal alloys employed in making dental implants and biomedical devices in stomatology. According to the invention, the materials are made of successive thin layers as follows : the first layer comprises metal Ti with a thickness ranging between 50...200 nm, the second layer comprises stoichiometric nitrides such as TiN or ZrN with a thickness ranging between 0.5...2 μm, the third layer comprises stoichiometric oxynitrides such as TiON or ZrON with compositional gradient and with a thickness ranging between 0.5...2 μm, wherein the ratio O/(O+N) continuously varies between 0...1 starting from the lower nitride layer, and the last layer comprises stoichiometric oxides such as TiOor ZrOwith a thickness ranging between 1...4 μm, the total thickness of the layers varying between 2...8 μm, the critical normal forces in the scratch adhesion testing being higher than 22 N, with microhardness higher than 18 GPa, the amount of ions released in the Carter-Brugirard artificial saliva being lower than 35 μg/cmand with a cellular viability factor higher than 85% upon citotoxicity assay.

Description

The invention relates to materials made of biocompatible thin layers, with a compositional gradient, used to cover the metal alloys from which dental implants and biomedical devices from dentistry are made. The materials according to the invention are made of successive thin layers, thus; the first layer is composed of metallic Ti with a thickness between 50 and 200 nm, the second layer is composed of stoichiometric nitrides of TiN or. ZrN with a thickness between 0.5 and 2 pm, the third layer is composed of stoichiometric oxides of TiON or ZțON, with a compositional gradient and with a thickness between 0.5 and 2 pm, in which the ratio O / (O + N) varies continuously between 0 and 1, starting with the lower nitride layer, and the last layer is formed by stoichiometric oxides of TiO ₂ or ZrO ₂ with the thickness between 1 and 4 pm, the total thickness of the layers varying between 2 and 8 pm, the forces critical normal to the scratch adhesion test being greater than 22 N, with micro-hardnesses greater than 18 GPa, the amount of ions released in Carter-Brugirard artificial saliva being less than 35 pg / cm ² and with a cell viability factor higher 85% high in the cytotoxicity test

Claims: 2

Starting from the date we publish the patent application, the application provides, in a provisional way, to the applicant, the protection conferred according to the provisions of art.32 d-inLegeanri64 / 199 f, except in cases where the patent application has been rejected ^ withdrawn or considered as withdrawn. The extent of the protection conferred by the patent application is determined by the claims contained in the published publication in accordance with article 23 atinflf - (3f

BIOCOMPATIBLE SUBSTITUTE LAYERS WITH COMPOSITIONAL GRADIENT> 9

FOR COVERING OF METAL DENTAL IMPLANTS

DESCRIPTION THE STATE TRADE FOR INVENTIONS IN MARK | Application for invention patents Nr. 1 Date of filing. „..JP.

The invention relates to materials from biocompatible thin layers, in the form of thin layers with a compositional gradient, corrosion resistant, low porosity, adherent to the support they have been deposited, used to cover the metal alloys from which dental implants and biomedical devices are made. from dentistry.

At present, materials from which dental implants are made are known, especially those made of titanium and its alloys, austenitic stainless steel and CoCr alloys, having an average residence in the body of about 10-15 years. The major problems related to the degradation of the medical implants are generated by the occurrence of the phenomena of rejection by the body due to the cytotoxic reactions, but also from fatigue and wear. For increasing the tissue residence time of implants, various technologies have been used to improve the quality of their surfaces, either by thermochemical treatments or by coating them with thin layers with biocompatibility higher than that of the basic metal alloy.

The problem solved by this invention is the creation of protective thin layers, in the form of thin layers materials with biocompatible and bioactive properties, resistant to corrosion and wear, which determines the increase of the life of the dental implants of metallic alloys and the reduction of the toxic ion quantity. release them, without affecting their mechanical properties. The superior properties of the compositional gradient, biocompatible and bioactive materials, which are the subject of the invention, are generated by their resistance to the corrosive action of fluids in human saliva, by the use in the composition of the coating material of elements that do not produce adverse reactions upon their release in the human body. Compared with the layers with homogeneous composition, in the case of layers with a compositional gradient, in which the oxygen concentration increases gradually in layer concomitant with the decrease of the nitrogen, the increase of the adhesion to the substrate and the hardness, as well as the decrease of the mechanical stresses and the porosity, due to the specific composition, rich in nitrogen, of the first layers and the quasi-continuous variation of the crystalline structure, specific to each elemental composition of the compounds in the compositional gradient layer.

In order to increase the resistance to corrosion and to decrease the concentration of metal released from the metal alloys used for dental implants, various methods have been used to improve the quality of the surfaces by thermochemical treatments or page-1 (λ-2 Ο 1 Ο - Ο Ο 9 1 5 - 2 6 -09- 2010 Thin layers, so that the mechanical properties of the base alloy are not affected As the coating materials chosen for the present invention were used nitrates, oxynitrides and titanium and zirconium oxides. refers to biocompatible materials with a compositional gradient, in which the first layer is a layer of metallic Ti, which has the role of increasing the adhesion of the layer to the substrate, the second is a nitride layer of Ti (TiN) or Zr (ZrN), which has the role of increasing the hardness, the third layer consists of an oxinitride layer with a compositional gradient, of Ti (TiON) or Zr (ZrON), in which c the nitrogen concentration decreases progressively with increasing oxygen concentration, and the last layer is an oxide of Ti (T1O2) or Zr (ZrC> 2).

The monolayer material of metallic Ti, according to the invention, from the composition of the compositional gradient layer has a thickness between 50 and 200 nm.

The monolayer materials of Ti or Zr nitrides, according to the invention, from the composition of the compositional gradient layer, are made of thin layers of TiN or ZrN, with total thicknesses between 0.5 and 2 pm. The nitride monolayer materials have a ratio of elemental concentrations of non-metals and metals between 0.85 and 1.2.

The oxinitride materials of Ti or Zr, according to the invention, are made of thin layers of TiON or ZrON, with total thicknesses between 0.5 and 2 pm. The oxinitride layers show a ratio of elemental concentrations of nonmetals and metals between 0.85 and 2.1, and the ratio of elemental concentrations of nonmetals O / (O + N) shows a continuous variation, from the value 0, to the boundary with the layer. of nitride, up to value 1, at the border with the oxide layer.

The monolayer materials of Ti or Zr oxides, according to the invention, are made of thin layers of T1O2 or ZrO ₂ , with total thicknesses ranging from 1 to 4 pm. The thin layers of T1O2 and ZriZ> 2 show a ratio of elemental concentrations of oxygen and metals between 1.75 and 2.1.

Materials with a compositional gradient for covering dental implants and biomedical devices in dentistry from metal alloys, according to the invention, have the following advantages:

- they are adherent to the substrate, the normal forces critical to the scratch test being greater than 22 N;

- have micro-hardnesses with a minimum value of 18 GPa;

- the quantity of ions released in Carter-Brugirard artificial saliva at 37 ° C is less than 35 pg / cm ² , falling (according to ISO 8044) in the "perfectly stable" resistance class;

- has a cell viability factor greater than 85% in the cytotoxicity test.

page - 2 ^ -2010-00915-2 6 -09- 2010

The biocompatible materials with a compositional gradient, according to the invention, are obtained by a method of physical vapor deposition type (magnetron sputtering, cathodic arc, ionic plating, activated evaporation) in a reactive plasma.

The compositional gradient materials are obtained in a reactive plasma containing titanium, zirconium, oxygen and nitrogen atoms and ions, at pressures between 1x10 'and 10' Pa, at temperatures of the metal alloy on which the deposition is made between 80 °. and 350 ° C, which does not cause structural changes, the total deposition time being between 60 and 360 min.

An example of a layer with a compositional gradient is the one consisting of successive layers, starting with a metallic layer of Ti, with a typical thickness of 0.1 µm, followed by the layer of ZrN, with the ratio N / Zr = 1.05 and the thickness of 1.2 µm, followed by a layer of ZrON with the total thickness of 2.5 µm, having the ratio (O + N) / Ti = 1.2, and the ratio O / (O + N) shows a continuous variation from value 0 to value 1, followed by the last layer of ZrO ₂ , with the thickness of

1.5 µm, with the ratio O / Zr = 2. The material with a compositional gradient shows high adhesion to the substrate, the critical normal force on the scratch test is 35 N. The material with a compositional gradient has a micro-hardness of 22 GPa. The amount of ion released in Carter-Brugirard artificial saliva is approximately 20 pg / cm. The material with a compositional gradient has a cell viability factor of 90% in the cytotoxicity test.

Claims (2)

1. The thin layer materials with a compositional gradient characterized by the fact that: they are made of successive thin layers, the first layer consisting of metallic titanium having a thickness between 50 and 200 nm, the second of titanium nitride TiN having a thickness between 0.5 and 2 pm and the ratio between non-metals and metals between 0.85 and 1.2, the third layer being composed of Ti oxinitride (TiON) with a compositional gradient, with the thickness between 0.5 and 2 pm and having the ratio O / (O + N) varying continuously between 0 and 1, and the ratio between non-metals and metals between 0.85 and 2.1, the last layer being made of titanium oxide (T1O2), with the thickness between 1 and 4 pm, having the ratio between non-metals and metals between 1.75 and 2.1, with total thicknesses between 2 and 8 pm, with high adhesion to the substrate, the normal forces critical to the scratch test being greater of 22 N, with micro-hardnesses greater than 18 GPa, the amount of ion released in Carter-Brugirard artificial saliva being less than 36 pg / cm ² , the cell viability factor being greater than 85% in the cytotoxicity test. 2. The thin layer materials with a compositional gradient characterized by the fact that: they are made of successive thin layers, the first layer being made of metallic titanium having a thickness between 50 and 200 nm, the second of ZrN zirconium nitride having a thickness between 0.5 and 2 pm and the ratio between non-metals and metals between 0.85 and 1.2, the third layer being composed of Zr oxinitride (ZrON) with a compositional gradient, with the thickness between 0.5 and 2 pm and having the ratio O / (O + N) continuously varying between 0 and 1, and the ratio between non-metals and metals between 0.85 and 2.1, the last layer being made of zirconium oxide (ZrCh), with the thickness between 1 and 4 pm, having the ratio between non-metals and metals between 1.75 and 2.1, with total thicknesses between 2 and 8 pm, with high adhesion to the substrate, the normal forces critical to the scratch test (scratch test) being more larger than 22 N, with micro-hardnesses greater than 18 GPa, the amount of ion released in Carter-Brugirard artificial saliva being less than 35 µg / cm, the cell viability factor being more than 85% in the cytotoxicity test.