BR112014023878B1 - dental implant having a surface layer comprising an antimicrobial metal and method for its production - Google Patents

Abstract

abstract "medical device having a surface comprising an antimicrobial metal" a medical device intended for contact with a living tissue comprises a substrate having a surface, which surface comprises a layer comprising one or more compounds of at least one non-transition metal toxic, such as a gallium or bismuth compound. a layer comprising a compound of at least one non-toxic post-transition metal has been shown to inhibit film formation on the surface of the medical device, which can reduce the risk of infection, for example, around the dental implant. a method for producing the medical device comprises: a) providing a substrate having a surface; and applying a compound of at least one post-transition metal to such a surface to form a layer, for example, using a thin film deposition technique.

Description

“DENTAL IMPLANT HAVING A SURFACE LAYER UNDERSTANDING AN ANTIMICROBIAL METAL AND METHOD FOR ITS PRODUCTION”

FIELD OF THE INVENTION [001] The present invention relates to a medical device having a surface layer comprising an antimicrobial metal, and methods of producing such a device.

BACKGROUND [002] For any type of medical device that intends to contact living tissue, compatibility is a crucial issue. The risk of a foreign body reaction, clot formation, among other things, must be addressed and minimized in order to avoid adverse effects, local as well as systemic, which can, on the other hand, compromise the patient's health and / or lead to device failure. This is particularly the case for permanent implants.

[003] The healing or regeneration of tissue around an implant is generally vital in order to ensure the implant and its long-term functionality. This is especially important for load bearing implants such as dental or orthopedic implants.

[004] Dental implant systems are widely used to replace damaged or lost natural teeth. In such implant systems, a dental fixation (screw), usually made of titanium or a titanium alloy, is placed on the patient's jaw bone in order to replace the root of the natural tooth. A pivot structure is then attached to the fixation in order to build a core for the part of the prosthetic tooth extending from the bone tissue, through the soft gingival tissue and into the patient's mouth. In such a pivot, the prosthesis or crown can finally be seated.

[005] For dental fixations, a strong fixation between the bone tissue and the

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2/40 implant is required. For implants that intend to contact the soft tissue, such as pivots that are to be partially located in the soft gingival tissue, compatibility with the soft tissue is also vital to the full functionality of the implant. Typically, after implantation of a dental implant system, a pivot is partially or completely surrounded by gum tissue. It is desirable that the gum tissue should heal quickly and firmly around the implant, for both medical and aesthetic reasons. A tight fit between the oral mucosa and the dental implant serves as a barrier against the oral microbial environment and is crucial to the success of the implant. This is especially important for patients with poor oral hygiene and / or inadequate bone or mucosa quality. Weak scarring or weak attachment between the soft tissue and the implant increases the risk of infection and peri-implantitis, which can ultimately lead to bone resorption and implant failure.

[006] There are several strategies to increase the chances of a successful implantation of a medical device, for example, increasing the rate of formation of a new tissue and / or, in cases where the implant-tissue connection is desired, increasing the rate of tissue attachment to the implant surface, or reducing the risk of infection. The increase in the formation of new tissue can be achieved, for example, by various modifications on the surface and / or by the deposition of bioactive agents on the surface.

[007] The risk of infection in connection with dental implants is now faced mainly by preventive measures, such as maintaining good oral hygiene. Once a biofilm is formed on the surface of a dental implant, it is difficult to remove by applying antibacterial agents. In the case of infection in the bone or soft tissue around the dental implant (peri-implantitis), a mechanical debridement is the basic element, sometimes in combination with antibiotics, antiseptics, and either a laser or ultrasonic treatment.

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3/40

SUMMARY OF THE INVENTION [008] It is an objective of the present invention to overcome this problem, and to provide a medical device, such as an implant, having a surface that reduces the risk of infection after contact of the medical device with a living tissue.

[009] According to a first aspect of the invention, this and other objectives are achieved by a medical device intended to contact living tissue, comprising a substrate having a surface layer comprising one or more non-transition metal compounds toxic.

[010] The layer comprising one or more of a non-toxic post-transition metal, for example, gallium, may have an atomic concentration (% at) of post-transition metal, for example, gallium and / or bismuth, of at least 5% at. In the embodiments of the invention, the concentration of gallium in such a layer is at least 10% at, for example, at least 15% at, for example, at least 20% at. However, in other embodiments of the invention, the post-transition metal content can be less than 5%, for example, at least 0.05% at. The layer can have a gallium content of up to 50% at.

[011] In the embodiments of the invention, the compound of a non-toxic postransition metal makes up most of the layer.

[012] A medical device surface having a layer incorporating a non-toxic post-transition metal such as gallium or bismuth has been shown to be effective against various bacterial strains, and has been shown to inhibit biofilm formation in vitro. The medical device according to the invention can also be effective against other microbes, such as fungi.

[013] In the embodiments of the invention, such living tissue is a soft tissue. Alternatively, such living tissue can be cartilage or bone tissue.

[014] In the embodiments of the invention, such one or more compounds of a non-toxic post-transition metal also comprises an additional metal, for example,

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4/40 a biocompatible metal such as titanium. Titanium is known to be well tolerated by living tissue, and has been used as an implant material for many years. Including a biocompatible metal, for example, titanium, in the gallium-containing layer, a surface is obtained which is more similar to the surfaces of established implants and which is even more possible to be well tolerated by living tissue.

[015] In the embodiments of the invention, the surface layer can be a metallic layer. The compound comprising a non-toxic post-transition metal can be a metallic compound.

[016] In the embodiments of the invention, the non-toxic post-transition metal is selected from bismuth and gallium. Therefore, the non-toxic post-transition metal compound (s) can be selected from bismuth compound (s) and gallium compounds.

[017] A gallium compound can be selected from a group consisting of gallium titanium oxide, gallium nitride, gallium titanium nitride, gallium carbide, gallium selenide, and gallium sulfide, gallium chloride, gallium fluoride, gallium iodide, gallium oxalate, gallium phosphate, gallium maltolate, gallium acetate, and gallium lactate. A bismuth compound can be selected from a group consisting of titanium-bismuth, titanium-bismuth oxide, bismutotitanium nitride, bismuth nitride, bismuth carbide, bismuth selenide, and bismuth sulfide, bismuth chloride, fluoride of bismuth, bismuth iodide, bismuth oxalate, bismuth phosphate, bismuth maltolate, bismuth acetate, and bismuth lactate. These non-toxic post-transition metal compounds are generally well tolerated by living tissue in a mammal, and can be deposited on a surface using a thin film deposition technique.

[018] In the embodiments, the compound of a non-toxic post-transition metal is a nitride of at least one non-toxic post-transition metal, such as a gallium nitride or a bismuth nitride, also optionally comprising

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5/40 titanium. Nitrides containing non-toxic post-transition metal such as gallium or bismuth are particularly useful in the present invention, in particular for dental implant applications, because such compounds can provide an aesthetically desirable surface layer, in particular in relation to color. Such nitrides can be deposited using thin film deposition techniques. Nitride from a non-toxic post-transition metal can be selected from a group consisting of gallium-titanium nitride, gallium nitride, bismuth-titanium nitride, bismuth nitride, and gallium-bismuth-titanium nitride.

[019] In the embodiments of the invention, the layer comprising a non-toxic post-transition metal compound may further comprise a non-toxic post-transition metal salt, for example, a gallium salt or a bismuth salt. The salt can be deposited on the surface layer comprising the compound of a non-toxic post-transition metal. For example, a gallium salt or a bismuth salt can be deposited on the first layer comprising a first gallium or bismuth compound. A salt deposit can increase the release of post-transition antimicrobial metal from the surface shortly after contact with living tissue, thus temporarily increasing an antibacterial or antimicrobial effect of the layer.

[020] Generally, the layer comprising the compound of a post-transition metal can have a thickness in the range of from 10 nm to 1.5 pm. A layer of at least 10 nm may be sufficient to provide a desirable antibacterial effect, while layers of thickness up to 1 pm may be desirable for aesthetic reasons, having a compatible color for, for example, dental implants.

[021] Typically, in the embodiments of the invention, the layer comprising the compound of a non-toxic post-transition metal can be a homogeneous layer. The layer can also be a non-porous layer. A layer

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Non-porous 6/40 is typically less susceptible to bacterial growth and biofilm formation compared to a porous layer.

[022] The substrate on which the layer comprising at least one gallium compound is provided can comprise a metallic material, typically a metal or a biocompatible alloy such as a titanium or titanium alloy. Alternatively, the substrate can comprise a ceramic material. In other embodiments, the substrate may comprise a polymeric material, or a composite material.

[023] The medical device of the invention is typically an implant intended for long-term contact with, or implantation into, living tissue. In one embodiment, the medical device is an implant intended for implantation at least partially in the soft tissue. In still other embodiments of the invention, the medical device may be intended for short or prolonged contact with living tissue, typically soft tissue.

[024] For example, the medical device may be a dental implant, in particular a dental pivot. In another embodiment, the medical device may be a hearing device anchored to the bone. In another embodiment, the medical device may be an orthopedic implant. In another embodiment, the medical device may be a stent. In another embodiment, the medical device may be a shunt. As another example, the medical device may be a catheter adapted for insertion into a body cavity such as a blood vessel, digestive tract or urinary system.

[025] In another aspect, the invention provides a method of producing a medical device as described here, comprising

a) providing a substrate having a surface; and

b) applying a non-toxic post-transition metal compound to such a surface to form a layer.

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7/40 [026] Typically, the compound of a non-toxic post-transition metal is a non-toxic post-transition metal nitride, such as a gallium and / or bismuth nitride.

[027] In some embodiments, step b) involves applying simultaneously or sequentially a non-toxic post-transition metal and an additional metal or metal compound to such a surface. The additional metal or metal compound may comprise titanium. Applying the post-transition metal, and also optionally an additional metal or metal compound, can be achieved using a thin film deposition technique.

[028] A medical device as described above can be used to prevent biofilm formation and / or bacterial infection from surrounding tissue, in particular soft tissue. In particular, the medical device of the invention can be used for the prevention of bacterial infection of gingival tissue and / or peri-implantitis.

[029] It is noted that the invention refers to all possible combinations of aspects recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS [030] Figure 1 is a side view of a medical device according to an embodiment of the invention, in which the medical device is a dental pivot.

[031] Figure 2 illustrates, in cross section, a part of a medical device according to the modalities of the invention, showing a substrate material and a layer comprising a gallium compound.

DETAILED DESCRIPTION OF THE INVENTION [032] The present inventor has discovered that a medical device having a surface layer comprising a post-transition metal compound, in particular a non-toxic antimicrobial post-transition metal, such as gallium and / or bismuth , provides several beneficial effects in terms of reduced risk of

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8/40 infection, improved tissue healing and / or aesthetic performance. The inventor has demonstrated that the titanium body having a surface coating incorporating gallium (Ga) can prevent the growth of bacteria on and around the surface and thus can be useful in preventing harmful infection around, for example, a pin implanted in the gum. It has also been shown that the titanium body having a surface coating incorporating bismuth (Bi) can prevent the growth of bacteria on and around the surface and thus can be useful in preventing harmful infection around, for example, the dental pin implanted in the gum.

[033] According to the present invention, a tissue contact surface of a medical device surface comprises a post-transition metal compound. Typically, the post-transition metal is non-toxic to mammalian cells at concentrations that have a lethal effect on bacterial cells.

[034] The term “post-transition metal” generally refers to metal elements found in groups 13-16 and periods 3-6 of the periodic table. Usually, aluminum, gallium, indium, thallium, tin, lead, bismuth and polonium are considered to be post-transition metals. In contrast, transition metals are formed from group 3-12 elements. Germanium and antimony are not considered post-transition metals, but metalloid elements.

[035] Group 16 of the periodic table contains only one postransition metal: polonium, which is toxic. Therefore, in the present invention, post-transition metals of groups 13-15 and periods 3-6 are preferred.

[036] In the embodiments of the invention, the post-transition metal used is non-toxic.

[037] As used here, “non-toxic” means that the substance (for example, a compound or element) in question does not harm mammalian cells in

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9/40 concentrations that have a lethal effect on bacterial cells.

[038] Examples of post-transition metals that are toxic include thallium (Tl), lead (Pb) and polonium (Po). Other post-transition metals (eg, indium (In) and tin (Sn)) can be considered non-toxic in the form of pure metal, but they can be toxic in other forms or when they form a compound with other elements.

[039] The non-toxic post-transition metal used in the present invention is typically non-toxic when present in its primary form, as metal ions, and / or as one of the exemplary compounds given here.

[040] In addition, the post-transition metal used in the present invention typically has an antimicrobial or antibacterial effect. Post-transition metals that are considered to have some antimicrobial or antibacterial effect (including any oligodynamic effect) include at least gallium, tin, lead and bismuth.

[041] In view of the above, the invention can employ at least one non-toxic antimicrobial post-transition metal, which is preferably selected from gallium and bismuth.

[042] For example, a gallium compound can be applied to a medical device as a surface layer. Alternatively, the gallium compound can be incorporated into at least part of a body forming a medical device, so that at least one surface of the device comprises the gallium compound.

[043] As another example, a compound and bismuth can be applied to a medical device as a surface layer. Alternatively, a bismuth compound can be incorporated into at least one part of the body forming a medical device, so that at least one surface of the device comprises the bismuth compound.

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10/40 [044] Gallium has been used in medicine at least since the 1940s, primarily as a radioactive agent for medical imaging. The antibacterial properties of gallium have been investigated in several studies. In Kaneko et al. (2007) it was established that gallium nitrate (Ga (NO3) 3) inhibits the growth of Pseudomonas aeruginosa in batch cultures. Olakanmi et al (2010) found that Ga (NO3) 3 inhibited the growth of Francisella novicida. Gallium works by disrupting iron metabolism. It can be assumed that gallium is also effective against other microbes, for example, fungi such as yeasts or molds.

[045] Bismuth is known to have antibacterial activity. Bismuth compounds were previously used to treat syphilis, and bismuth subsalicylate and bismuth subcitrate are currently used to treat peptic ulcers caused by Helicobacter pyroli. The mechanism of action of this substance is still not well understood. Bibrocathol is a compound containing organic bismuth used to treat eye infections, and bismuth subsalicylate and bismuth subcarbonate are used as ingredients in anti-diarrhea drugs.

[046] A directive 2007/47 / ec defines a medical device as: any instrument, device, device, software, material or other article, whether used alone or in combination, including the software intended by its manufacturer to be used specifically for the diagnosis and / or therapeutic purpose and necessary for its own application, intended by the manufacturer as being for human beings ”. In the context of the present invention, only medical devices intended for contact with living tissue are considered, that is, any instrument, apparatus, device, material or other article of a physical character that is intended to be applied to, inserted into, implanted in or otherwise brought into contact with the body, a body part or an organ. Furthermore, such a body, body part or organ may be that of a human individual

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11/40 or animal, typically a mammal. Preferably, however, the medical device is intended for human individuals. The medical devices included within the definition above are, for example, implants, catheters, shunts, tubes, stents, intrauterine devices and prostheses.

[047] In particular, the medical device may be a medical device intended for implantation into living tissue or for insertion into an individual's body or part of the body, including the insertion of the body cavity.

[048] The present medical device can be intended for short-term, prolonged or long-term contact with living tissue. By "short term" means a duration of less than 24 hours, according to the definitions found in ISO 10993-1 for biological evaluations of medical devices. In addition, "extended", according to the same standard, refers to a duration of 24 hours up to 30 days. Therefore, by the same pattern, “long term” means a duration of more than 30 days. Thus, in some embodiments, the medical device of the invention may be a permanent implant, intended to remain for months, years or even throughout an individual's life.

[049] As used here the term "implant" includes within its scope any device of which at least a part is intended to be implanted in the body of a vertebrate animal, in particular a mammal, such as a human. Implants can be used to replace anatomy and / or restore any body function. Generally, an implant is made up of one or more implant parts. For example, a dental implant usually comprises a dental fixation coupled to secondary implant parts, such as a pivot and / or a restorative tooth. However, any device, such as a dental fixation, intended for implantation can alone be referred to as an implant even if the other parts are to be connected there.

[050] By "biocompatibility" means a material that, after contact with

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12/40 the living tissue as such does not cause an adverse biological response (eg, inflammation or other immune reactions) of such tissue.

[051] By "soft tissue" means any type of tissue, in particular the types of mammalian tissue, other than bone or cartilage. Examples of soft tissue for which the medical device is compatible include, but are not limited to, connective tissue, fibrous tissue, epithelial tissue, vascular tissue, muscle tissue, mucosa, gum and skin.

[052] As used here, the term "post-transition metal compound" refers to a chemical entity comprising at least one post-transition metal and at least one additional element. Non-limiting examples of such compounds include oxides comprising post-transition metals, nitrides comprising post-transition metals, alloys of at least one post-transition metal, and salts comprising post-transition metals. The compound can comprise two or more post-transition metals. The term "composed of a post-transition metal" is also intended to refer to compounds incorporating one or more other metals, in particular biocompatible metals such as titanium, in addition to one or more post-transition metals. Therefore, as used herein, the term "gallium compound" refers to a chemical entity comprising gallium and at least one additional element. Non-limiting examples of gallium compounds include gallium oxide, gallium nitride, and gallium salts. Gallium and at least one additional element can be joined by a covalent bond or an ionic bond. The term "gallium compound" is also intended to include compounds incorporating metals other than gallium, in particular titanium. Thus, gallium-titanium oxides, gallium-titanium nitrides, etc. are included within the definition of “gallium compound”.

[053] By analogy, the term "bismuth compound" refers to a chemical entity comprising bismuth and at least one additional element. The examples

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Non-limiting 13/40 bismuth compounds include bismuth oxide, bismuth nitride, and bismuth salts. Bismuth and at least one additional element can be joined by a covalent bond or an ionic bond. The term "bismuth compound" is also intended to include compounds incorporating metals other than bismuth, in particular titanium. Thus, bismuth-titanium oxides, bismuth-titanium nitrides, etc. are included within the definition of “bismuth compound”.

[054] As used herein, the "metallic compound" refers to a compound that comprises at least one metal and that has one or more properties that are associated with metals, such as a glossy metallic color. A metallic compound can be formed by one metal and one non-metal, or two or more metals. Therefore, a metallic compound does not need to comprise non-metallic elements, but it can be formed of metallic elements only. In the context of the present invention, at least the following compounds are considered metallic compounds: gallium nitride, gallium-titanium nitride, gallium-titanium, gallium-bismuth-titanium, gallium-bismuth-titanium nitride, bismuth nitride, nitride nitride bismuth-titanium and bismuth-titanium.

[055] As used here, a "homogeneous layer" refers to a layer having a chemical composition that is uniform in all directions (three dimensions).

[056] Figures 1 and 2 illustrate an embodiment according to the present invention in which a medical device is a dental pivot. A dental pivot (100) comprises a body of substrate material (102) coated with a layer (101) comprising a gallium compound. The layer (101) forms the surface of the pivot that must face and contact the gingival tissue after implantation.

[057] The medical device of the invention can be made of any suitable biocompatible material, for example, the materials used for the devices

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14/40 implantable. Typically the medical device comprises a substrate having a surface comprising a post-transition metal compound, such as a gallium compound or a bismuth compound. The substrate can, for example, be made of a biocompatible metal or metal alloy, including one or more materials selected from a group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, cobalt and iridium, and alloys of the same. Alternatively, the substrate of the medical device can be made of biocompatible ceramics, such as zirconia, titania, metal ceramics with shape memory and combinations thereof. In the modalities where the medical device is used as or forms part of a dental pivot, the substrate is preferably made of a metallic material.

[058] In contact with oxygen, the metals of titanium, zirconium, hafnium, tantalum, niobium and their alloys react instantly to form an inert oxide. In this way, the article surfaces of these materials are virtually always coated with a thin layer of oxide. The natural oxide layer of a titanium substrate consists mainly of titanium (IV) dioxide (TiO2) with smaller amounts of TÍ2O3, TiO and TÍ3O4.

[059] Thus, the modalities where the medical device comprises one or more of titanium, zirconium, hafnium, tantalum, niobium or an alloy of any of them, the medical device typically has a natural metal oxide surface layer. Such a layer of natural metal oxide may in part be coated with a thin film comprising the gallium compound. Alternatively, a natural metal oxide layer can be modified or replaced with a modified surface layer incorporating a post-transition metal, such as gallium or bismuth, for example, a titanium-gallium oxide layer or one of titanium-bismuth oxide.

[060] In other embodiments of the present invention, the medical device, in

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15/40 particularly the substrate, can be made of a biocompatible polymer typically selected from a group consisting of polyether ether ketone (PEEK), poly methyl methacrylate (PMMA), poly lactic acid (PLLA) and poly glycolic acid (PGA ) and any combinations and copolymers thereof.

[061] In the embodiments of the invention, the medical device is intended for short-term, prolonged or long-term contact with living tissue. For example, the medical device of the invention may be an implant typically intended to temporarily or permanently replace or restore a body function or structure.

[062] Typically, at least part of the surface of the medical device is intended for contact with the soft tissue, and at least part of this contact surface of the soft tissue has a layer comprising a post-transition metal compound, for example. example a gallium compound or a bismuth compound. For example, the medical device may be an implant intended to contact soft tissue first or exclusively, for example, a dental pivot. Alternatively, the medical device may be an implant to be inserted partially into the bone and partially into the soft tissue. Examples of such implants include one-piece dental implants and bone-anchored hearing devices (also referred to as bone-anchored hearing aids). Where only part of the implant is intended for contact with the soft tissue, it is preferred that the layer comprising the post-transition metal compound, for example, a gallium or bismuth compound, is provided at least on a part of a surface of soft tissue counting.

[063] The medical device may also be compatible for contact with cartilage.

[064] In other modalities, the medical device may be intended for contact with bone tissue, for example, the maxillary bone, the femur or the skull of

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16/40 a mammal, in particular a human. Examples of such medical devices include dental fixatives and orthopedic implants.

[065] In the embodiments of the invention, the post transition metal compound can be a gallium compound and / or a bismuth compound. Compatible compounds include in particular compounds that can be applied to a surface using a thin film deposition technique.

[066] Examples of compatible gallium compounds include gallium oxide, gallium nitride, gallium carbide, gallium selenide, gallium sulfide, and other gallium salts that can be deposited using a thin film deposition, for example, gallium chloride, gallium fluoride, gallium iodide, gallium oxalate, gallium phosphate, gallium maltolate, gallium acetate and gallium lactate.

[067] In the embodiments of the invention, the gallium compound comprises at least one gallium oxide (Ga2O3). Gallium oxide can be present in an amorphous or crystalline form. Crystalline forms of gallium oxide include a-Ga2O3,

3-Ga2O3, y-Ga2O3, ô-Ga2O3, and s-Ga2O3.

[068] Examples of compatible bismuth compounds include bismuth oxide, bismuth nitride, bismuth carbide, bismuth selenide, bismuth sulfide, and other bismuth salts that can be deposited using a thin film deposition, for example, bismuth chloride, bismuth fluoride, bismuth iodide, bismuth oxalate, bismuth phosphate, bismuth maltolate, bismuth acetate and bismuth lactate.

[069] The compound of a post-transition metal can optionally include at least one other metal, such as titanium. Therefore, in embodiments of the invention, a gallium compound can be selected from a group consisting of gallium oxide, gallium-titanium oxide, gallium nitride, galliotitanium nitride, gallium-titanium, gallium-bismuth-titanium, and gallium-bismuth-titanium nitride. Similarly, a bismuth compound can be selected from a group

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17/40 consisting of bismuth oxide, bismuth-titanium oxide, bismuth nitride, bismuth-titanium nitride, bismuth-titanium, bismuth-gallium-titanium, and bismuth-galliotitanium nitride.

[070] Not wishing to be limited by any particular theory, it is believed that after contact with living tissue and / or body fluids, a layer of, for example, gallium oxide or gallium nitride (optionally comprising an additional metal such as titanium) exhibits a slow sustained release of gallium ions. Such a release can be slower and more sustained compared to the release of gallium ions from the precipitated gallium salt, and can thus provide a greater long-term effect in relation to biofilm formation. In addition, a deposited surface layer using a thin film deposition method as used in the embodiments of the invention adheres firmly to the adjacent substrate and thus avoids problems related to exfoliation and flaking of the surface layer. Exfoliation and peeling can cause an adverse inflammatory response to the surrounding tissue, and in addition can weaken the biofilm prevention effect of the surface layer.

[071] Depending on the intended use of the medical device, different release properties may be desired. For example, a higher release rate of antimicrobial post-transition metal may be more favorable for short-term use, that is, for a medical device intended for short-term contact with living tissue, compared to an intended device for prolonged or long-term contact. The rate of release can be affected by several factors, for example, the crystallinity of the compound.

[072] Optionally, in the embodiments of the invention the medical device may additionally comprise a post-transition metal salt, for example, a gallium salt selected from a group consisting of gallium acetate, gallium carbonate, chloride gallium, gallium citrate, gallium fluoride, shape

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18/40 gallium, gallium iodide, gallium lactate, gallium maltolate, gallium nitrate, gallium oxalate, gallium phosphate, and gallium sulfate. Alternatively, the salt may be a bismuth salt formed from any of these counterions. Such a salt can be provided as a deposit, for example, precipitated on the layer comprising the compound of a post-transition metal.

[073] As mentioned above, the post-transition metal compound, for example, a gallium compound or a bismuth compound, is typically contained in an applied surface layer. In the embodiments of the invention, the compound, optionally including another metal such as titanium, can make up most of such a layer. The atomic concentration (% at) of the elements together forming the compound of a post-transition metal constitutes at least 50% at least of the layer, preferably at least 70% at and most preferably at least 80% at the layer elements.

[074] The atomic concentration of the post transition metal, for example gallium, in the layer can be in the range of about 5% to up to 50% at, for example at least 10% to, at least 15% at, at least 20% up to at least 35% up to or at least 30% up to, and up to, for example, 50% up to, such as up to 45% up to, or up to 40% up to. However, in the embodiments of the invention, the atomic content of the post transition metal can be less than 5% at. For example, the atomic content of the post-transition metal can be in the range of about 0.01 to about 20% at, for example from about 0.05 to about 15% at, such as about 0.1 at about 15% at. For example, in embodiments where the post-transition metal compound comprises gallium, the gallium content in the layer can be at least 0.05% at or at least 0.1% at, for example at least 0.3% at or at least 0.5% at. In embodiments where the post-transition metal compound comprises bismuth, the bismuth content in the layer can be, for example, at least 0.1% to at least 0.2% to, for example at least 1% to or at least 1.5% at.

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19/40 [075] When the gallium compound is substantially a pure gallium oxide (Ga2O3), the maximum gallium content in the layer is 40% at, and the maximum oxygen content in the layer is 60% at. However, impurities and contamination, for example, carbon, can be present in up to 20% at. If the gallium compound is a gallium-titanium oxide, part of the gallium is replaced with titanium and then the total gallium and titanium content would be 40% at.

[076] When the gallium compound is substantially a pure gallium nitride (GaN), the maximum gallium content in the layer is 50% at, and the maximum nitrogen content is 50% at. Contaminations can be present as described above. If part of the gallium is replaced by another metal, such as titanium, the total gallium content and such another metal may still be 50% at, or it may be higher, for example, up to 75%, if the nitrogen content is low . As an example, the layer may contain 50% at nitrogen, 25% at titanium and 25% at gallium.

[077] The atomic concentration can be measured, for example, at a depth of 40 nm or less, and preferably not more than the thickness of the layer. Atomic concentration can be measured using X-ray photoelectron spectroscopy (XPS).

[078] As mentioned above, after contact with living tissue, some post-transition metals, such as gallium or bismuth, may be released from the surface of the medical device over time. Therefore, after implantation, the post-transition metal content and possibly also the other materials present on the surface of the medical device may change over time.

[079] In some embodiments, the layer may in addition to the post-transition metal compound include one or more other elements or compounds (a dopant), for example, in a content of 10% at or less, as will be described in further details below. The layer comprising the gallium compound or another compound of a post-transition metal may also contain impurities or

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Contamination, for example carbon, typically in an amount of 20% up to or less, and preferably 15% up to or less, or 10% up to or less. Such contamination can originate from packaging. It can be noted that wet packaging, in which the surface can be protected by water, ethanol or the like, reduces the amount of carbon contamination, compared to dry packaging where the surface is exposed to air that normally contains volatile hydrocarbons. Contamination can also be present on the substrate surface before the layer comprising the gallium compound is applied. The level of contamination, typically represented by the atomic concentration of carbon, can be reduced by cleaning the surface before applying the post-transition metal compound and / or avoiding further contamination of the surface before measuring the atomic concentration of the elements on the surface.

[080] Table 1 summarizes the possible atomic concentration ranges for the layer comprising bismuth nitride, bismuth titanium nitride, gallium oxide, gallium titanium oxide, gallium titanium oxide, gallium nitride or galliotitanium nitride , respectively.

TABLE 1. Exemplary atomic concentrations and various elements of a gallium compound.

Atomic concentration (% at) Bismuth Nitride / Bismuth Titanium Nitride Gallium oxide / Galiotitanium oxide Gallium nitride / Galliotitanium nitride Ga - 5-40% at 0.1-50% at; For example 550% at Bi 0.1-50% at - - You 0-at; For example, 25-75% at 0-35% at 0-75% at; For example, 045% at; for example, 1060% at O - 7.5-60% at - N 5-50% at; For example, 20-50% at - 5-50% at; For example, 20-50% at

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21/40 [081] In the embodiments of the invention, the compound of a post-transition metal can primarily comprise a post-transition metal and an additional metal, such as titanium. For example, the surface layer can comprise titanium-gallium or titanium-bismuth as the compound of a post-transition metal. In such embodiments, the post-transition metal content can be in the range of about 0.01 to 20% to, for example, about 0.05 to 15% to, such as about 0.1 to 15% % at, as described above. In addition, the titanium content can be in the range of about 10 to 99.9% at, for example, 10 to 60% at, or 10 to 30% at. The layer may additionally contain nitrogen in a content of about 0 to 15% at. For example, the nitrogen content of the layer can typically be in the range of about 0 to 5% at. In addition, depending on the handling (eg cleaning steps) and / or the analytical technique used to determine the chemical composition of the surface, the layer may additionally have a relatively high but superficial oxygen content, for example, about 0 to up to about 60% at.

[082] In some embodiments, the surface layer consists essentially of one or more of the post-transition metal compounds mentioned above. According to the above, “essentially consists of” here means that the layer contains little or no other material (dopants, contaminants, etc.) except one or more compounds of a post-transition metal, only, for example, up to 10% to, preferably up to 5% to, more preferably up to 2% to and even more preferably up to 1% to other material.

[083] In general, the layer comprising a post-transition metal compound, for example, a gallium compound or a bismuth compound, is free of carrier material such as polymers, solvents, etc.

[084] The layer comprising a post-transition metal compound such as a gallium compound or a bismuth compound may have a thickness

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22/40 in the range from 1 nm to 1.5 pm, for example, 0.1 to 1 pm, in particular from about 0.3 to 1 pm. A layer having a thickness of at least 1 nm can provide a sufficient antimicrobial effect. Increasing the thickness of the layer can provide a whiter color, which may be desirable for dental applications. However, also a layer having a thickness of about 10 nm can be more aesthetically advantageous than the commercially present dental pivots. For example, a 40 nm gallium oxide layer has a dark bronze color that could be less visible through the patient's gums than today's metallic gray titanium pivots.

[085] Where primarily an antimicrobial effect is requested, the layer containing the post-transition metal compound can optionally have a thickness of about 10 to 100 nm, or optionally up to 300 nm. On the other hand, where the aesthetic appearance of, for example, a dental pivot is of high importance, a layer thickness in the range of about 0.5 to 1.5 pm, for example, about 0.7 to 1 , 5 pm or about 0.7 to 1 pm may be preferred. However, even the thinner layers can provide an appearance of acceptable color and which can be at least more advantageous than the dental pivots of the prior art.

[086] The layer can be a dense layer, that is, a non-porous layer.

[087] In the embodiments of the invention, the surface of the medical device may comprise a single layer. Alternatively, in other embodiments, the medical device may comprise multiple layers, at least one comprising a post-transition metal compound such as a gallium compound or a bismuth compound.

[088] In the embodiments of the invention, a non-toxic post-transition metal salt, optionally forming another layer, can be provided in

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23/40 at least part of the thin film deposited layer comprising the aforementioned non-toxic post-transition metal compound. For example, a solution of at least one gallium salt can be applied to a layer deposited with a thin film of a post-transition metal compound, and allowed to evaporate. Such modalities can provide a high initial gallium release after contact with living tissue, which can be advantageous in many cases, for short-term, prolonged as well as long-term tissue contact.

[089] In the embodiments of the invention, a surface layer of a medical device can contain at least one additional element or compound, for example, a bioactive element or compound that can further enhance tissue healing or function. Such elements or compounds can be included as a dopant in the layer comprising the compound of a post-transition metal, typically in a content of 10% at or less. Alternatively such elements or compounds can be applied as a separate layer, for example, to the layer comprising the compound of a post-transition metal.

[090] In the embodiments of the invention, the substrate may have a rough surface on which a layer comprising the post-transition metal compound is arranged. Since the layer comprising the composite of a post-transition metal can be thin, for example 100 nm or less, it can have good coverage of the conformal step, meaning that the layer follows the roughness of the underlying surface and preserves it substantially without making it smooth. However, in embodiments where the layer comprising a post-transition metal compound is relatively thick, it can reduce the surface roughness of the underlying substrate.

[091] The roughness of the substrate surface, and therefore optionally also the surface of the medical device formed by the layer comprising the gallium compound of a post-transition metal, can have a

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24/40 surface roughness with an average of Ra of at least 0.05 μm, typically at least 0.1 μm, for example, at least 0.2 μm. Since surfaces having an average surface roughness of (Ra) of at least 0.2 μm are believed to be more susceptible to biofilm formation, a layer comprising a post-transition metal compound, for example, a gallium compound or bismuth compounds as described here can be particularly advantageous for medical devices having a surface roughness of at least 0.2 pm, and can be highly useful for preventing biofilm formation in medical devices still having a roughness of larger surface. As an example, a dental pivot comprising a titanium substrate can have a surface roughness of about 0.2-0.3 pm. A surface layer of, for example, a gallium compound having a thickness of about 40 nm can substantially preserve this surface roughness (which may be desirable, for example, in order to facilitate a firm anchorage of the implant in the surrounding tissue) , but it can prevent the formation of biofilm on the implant surface and thus reduce the risk of infection and peri-implantitis.

[092] The layer comprising a post-transition metal compound can be formed by applying the post-transition metal compound to the surface of a medical device to form a surface layer. The post-transition metal compound can be applied using known deposition techniques, especially thin film deposition techniques. Compatible techniques may include physical deposition, chemical deposition and physical-chemical deposition. An example of such techniques is atomic layer deposition (ALD) which can be used to provide, for example, a layer of gallium oxide on the surface of the substrate (Nieminen et al, 1996; Shan et al, 2005). Other techniques that can be used for deposition of deposited chemical vapor (Pecharroman et al, 2003; Kim et al, 2010), spray pyrolysis deposition (Kim & Kim, 1987; Hao et al,

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2004), arc discharge deposition (Heikman et al, 2006), electron beam deposition (Al-Kuhaili et al, 2003), pulsed laser deposition (Orita et al, 2002), thermal evaporation deposition (Karaagac & Parlak, 2011), sputter deposition (Kim & Holloway, 2004) and molecular beam deposition (Passlack et al, 1995). The techniques of physical deposition, chemical deposition, and physical-chemical deposition can also be used to incorporate additional elements into the layer of post-transition metal compounds, for example, as dopants, in order to increase healing or tissue regeneration. contacting the medical device.

[093] ALD and other thin film deposition techniques are associated with several advantages for the deposition of a post-transition metal compound, such as controlled layer thickness, controlled composition, high purity, conformal step coverage, good uniformity (resulting in a homogeneous layer), and good adhesion. In particular, PVD can provide dense layers with excellent adhesion to the underlying substrate.

EXAMPLES

EXAMPLE 1A. PRODUCTION OF SPECIMENS COATED WITH GALLIUM OXIDE [094] Coins of a commercially pure titanium (cp) (grade 4) were manufactured and cleaned prior to the deposition of a 40 nm thick layer of amorphous Ga2O3 using an atomic layer deposition (Picosun, Finland) with precursors of GaCl3 and H2O, respectively. The specimens were then packed in plastic containers, and sterilized with electron beam irradiation.

EXAMPLE 1B. CHARACTERIZATION OF THE SURFACE OF SPECIMENS COATED WITH GALLIUM OXIDE [095] For all surface characterization experiments, eight

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26/40 specimens each of a commercially pure titanium (cp), Ga2Ü3 coated cp titanium produced as described above, and commercially available TiN coated c titanium, were prepared as described in example 1 (clean, coated using ALD in the case of specimens coated with Ga2Ü3, packaged and sterilized). Specimens coated with TiN were included for comparison since a TiN coating is known to provide a very weak antibacterial effect.

[096] The surface morphology and surface roughness were found to be unchanged by the ALD coating, but there was a slight increase in hydrophobic properties.

a) Surface Chemistry [097] Surface morphology and surface chemistry were analyzed with an ambient scanning electron microscope (XL30 ESEM, Philips, Netherlands) / energy dispersive spectroscope (Genesis System, EDAX Inc., USA) at an acceleration voltage to 10-30 kV. The elements detected on the surface of the specimens coated with Ga2O3 were oxygen (O), gallium (Ga), and titanium (Ti). Ga concentrations ranged from 4 to 9% atomic (% at), as measured with the acceleration voltages at 30 kV and 10 kV, respectively. The analytical depth with this technique is estimated to be approximately 1 μm, that is, much deeper than the thickness of the layer. No difference in terms of surface morphology can be detected between the controls of commercially pure titanium and titanium coated with Ga2O3.

[098] Additionally, surface chemistry was analyzed with an X-ray photoelectronic spectrometer (XPS, Physical Electronics, USA), which is a more sensitive surface technique than the energy dispersive spectrometer. As an AlKa monochrome X-ray source was used, the beam was focused at 100 μm. The detected elements were oxygen (O), gallium (Ga), and carbon (C). At

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27/40 gallium concentrations varied between 34 and 37% at. Oxygen concentrations varied between 47 and 50% at. The analytical depth with this technique is estimated to be approximately 5-10 nm. The results are summarized in table 2.

TABLE 2. Atomic concentration of elements detected using Xps

Element % at detected using XPS (depth 5-10 nm) Ga 34-37% at O 47-50% at Ç 13-18% at

b) Surface Morphology [099] The surface roughness was measured with a surface prophylometry (Hommel T1000 wave, Hommelwerke GmbH, Germany). A vertical measurement in the 320 pm range, and a 4.8 mm length assessment were used. Two specimens of each type were included in the analysis, and three measurements per specimen were performed. The surface roughness Ra was calculated after using a filtering process, with a cut-off point of 0.800 mm. The results are shown in table 3.

TABLE 3. Surface roughness (Ra) ± standard deviations (SD)

Tested specimens Ra (pm) Titanium coated with TiN 0.28 ± 0.01 Titanium coated with Ga2O3 0.31 ± 0.04 Uncoated titanium 0.34 ± 0.03

c) Wettability [0100] In order to investigate wettability, the contact angle was measured using a contact angle measurement system (Drop Shape Analysis System DSA 100, Kruss GmbH, Germany). The measurements were performed with deionized water. The results indicate that all specimens were hydrophobic (> 90 °), see table 4.

TABLE 4. Contact angle (°) ± standard deviations (SD)

Tested specimens Contact angle (°) Titanium coated with TiN 95.0 ± 1.4 Titanium coated with Ga2O3 97.7 ± 2.2 Uncoated titanium 92.0 ± 2.8

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EXAMPLE 1C. ANTIMICROBIAL EFFECT OF SURFACES COATED WITH GALLIUM OXIDE [0101] It has been found that a titanium body having a surface comprising gallium (Ga) in the form of gallium oxide can prevent the growth of Pseudomonas aeruginosa and Staphylococcus aureus on and around a surface and thus can be useful in preventing harmful infections around, for example, a dental pivot implanted in the gums.

a) Inhibition of Bacterial Growth in the Exhausted Plate [0102] In a first experiment, commercially pure titanium coins (0 6.25 mm) with or without a titanium oxide coating were placed on agar plates containing homogeneously distributed colonies. Pseudomonas aeruginosa. After incubation for 24 hours at 37 ° C there was a colony-free zone widely visible surrounding the gallium oxide coins, in contrast to the titanium coins that were surrounded by bacterial colonies.

b) Inhibiting the Growth of Bacteria Using a Contact Film Method [0103] In a second experiment, a contact film method (Yasuyuki et al, 2010) was used. Depleted plates of Pseudomonas aeruginosa (PA01) or methylicin resistant Staphylococcus aureus (MRSA) were made and 1 colony was inoculated into 5 ml of triptych soy broth (TSB) in culture tubes and grown under stirring conditions for 18 hours. Cell density was measured on a spectrophotometer at OD 600 nm and counted using a cell counting chamber. The cell culture was adjusted with sterile TSB to 1-5 x 10 ⁶ cells / ml. Specimens of commercially pure titanium (cp) coins (0 6.25 mm), cp titanium coins with a gallium oxide coating, or cp titanium coins with a commercially available titanium nitride (TiN) coating

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29/40 were prepared aseptically and placed inside the respective wells of a 12-well plate. A thin transparent plastic film was perforated, and sterilized using 70% ethanol and UV irradiation on each side. A 15pl drop of bacteria in TSB was applied to each specimen. A plastic film per specimen was placed over the bacteria in the specimens so that the bacterial solution was spread evenly over the specimen's surface, ensuring good contact. After incubation for 24 hours at 30 ± 1 ° C, the film of each specimen was removed aseptically and washed by pipetting 1 ml PBS on the surface in a 2 ml Eppendorf tube separated by specimen. The specimens were transferred to the same Eppendorf tubes used when the film was washed. The first surface of each specimen was washed by pipetting the same PBS with which the film was previously washed. Then, the specimens were sonicated and for 1 minute and vigorously vortexed for 1 minute in the same tube used before when the film was washed. Serial dilutions and plate counting were performed. The plates were incubated for 24 hours and the numbers of colonies counted and recorded. The antibacterial activity of titanium coated with gallium oxide was determined to be 92% reduction against PA01 and 71% reduction against MRSA, compared to titanium, see tables 5 and 6.

TABLE 5. Count of viable (cfu / ml) ± standard deviations (SD) after 24 hours of incubation of test specimens against Pseudomonas aeruginosa (PA01) _________________________ _::

Tested specimens PA01 (cfu / ml ± SD) 24h Titanium coated with TiN 1.6E + 08 ± 1.2E + 08 Titanium coated with Ga2O3 7.4E + 07 ± 2.8E + 06 Uncoated titanium 1.0E + 09 ± 6.0E + 08

TABLE 6. Viability count (cfu / ml) ± standard deviations (SD) after 24 hours against methylicin-resistant Staphylococcus aureus (MRSA) .___________

Tested specimens MRSA (cfu / ml ± SD) 24h Titanium coated with 5.0E + 08 ± 6.0E + 07

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TiN Titanium coated with Ga2O3 2.2E + 08 ± 3.7E + 07 Uncoated titanium 7.6E + 08 ± 6.8E + 07

c) In situ effect on a biofilm [0104] In a third experiment, the antibacterial activity of titanium discs, with or without a gallium oxide coating, was evaluated in situ using a Live / Dead® BacLight ™ strain (Life Technologies Ltd, UK). The depletion plates of Pseudomonas aeruginosa (PA01) were made and 1 colony was inoculated to 5 ml of TSB in culture tubes and cultured under shaking conditions for 18 hours. Cell density was measured on a spectrophotometer at OD 600 nm and adjusted with sterile TSB to 1x10 ⁶ cells / ml. 400 μl of bacteria were aliquoted in 8 compartmentalized chambers. The biofilm was allowed to form for 24 hours at 35 ± 2 ° C. Specimens of commercially pure titanium (cp) coins (0 6.25 mm), titanium coins with a gallium oxide coating, or cp titanium coins with a titanium nitride (TiN) coating were prepared aseptically and applied to the biofilm. Antibacterial activity was analyzed in situ using Live / Dead® staining.

[0105] In situ analyzes indicated that both coatings of titanium nitride and gallium oxide have an antibiofilm activity compared to an uncoated titanium in terms of viability. In a 24-hour analysis, it was seen that the typical biofilm mushroom structure had disappeared for titanium nitride and gallium oxide. It was also found that more dead cells were seen in gallium oxide than in titanium nitride.

EXAMPLE 2A. PRODUCTION OF METAL OR NITRIDE COATED SPECIMENS [0106] Commercially pure titanium (cp) coins (grade 4) were manufactured and cleaned before depositing a 0.5-1 pm thick layer of both titanium-bismuth (TiBi) , titanium nitride with bismuth (TiNBi), titanium gallium (TiGa)

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31/40 regarding titanium nitride with gallium (TiNGa) using a physical vapor deposition (PVD). TiBi and TiGa targets were used for TiBi / TiNBi and TiGa / TiNGa, respectively. The specimens were then packed in plastic containers, sterilized with electron beam irradiation.

EXAMPLE 2B. CHARACTERIZATION OF THE SURFACE OF METAL OR NITRET COATED SPECIMENS [0107] For these surface characterization experiments, specimens of commercially pure titanium (cp), titanium coated with TiBi, titanium coated with TiNBi, titanium coated with TiGa and titanium coated with TiNGa produced as described in example 2A were used.

[0108] It was found that the surface morphology and surface roughness was unchanged by the PVD coating, and that both uncoated titanium and coated specimens had hydrophilic properties.

[0109] The nitride specimens (TiNGa, TiNBi) had a golden color, similar to the TiN surfaces in commercially available dental implants. The BiN or GaN surface layer is expected to have a golden appearance as well. In contrast, TiBi and TiGa specimens were metallic gray in color, similar to uncoated titanium specimens.

a) Surface morphology and surface chemistry [0110] The surface morphology and surface chemistry were analyzed with an ambient scanning electron microscope (XL30 ESEM, Philips, Netherlands) / energy dispersive spectroscope (Genesis System, EDAX Inc ., USA) at an acceleration voltage at 10 kV. The concentrations of bismuth (Bi) and gallium (Ga) in the coated specimens (TiBi, TiNBi, TiGa, TiNGa) were found to be up to 12.6% at for Bi and 1.1% at for Ga, measured with acceleration voltages at 10 kV. Other elements detected on the surfaces were titanium (Ti), nitrogen (N), oxygen (O), and carbon (C). The analytical depth with this technique is estimated

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32/40 as approximately 1 pm, that is, possibly deeper than the thickness of the layer. No difference in terms of surface morphology can be detected between the controls for commercially pure titanium and coated titanium (TiBi, TiNBi, TiGa, TiNGa).

[0111] Additionally, surface chemistry was analyzed with an X-ray photoelectronic spectroscope (XPS, Physical Electronics, USA), which is a more sensitive surface technique than the energy dispersive spectroscope. As the monochromatic X-ray source AlKa was used, the beam was focused at 100 pm. the detected elements were titanium (Ti), nitrogen (N), carbon (C), and oxygen (O), as well as bismuth (Bi) (for TiBi and TiNBi specimens) and gallium (Ga) (for TiGa and TiNGa). The concentrations of Bi and Ga were detected to be up to 3.3% at and 0.4% at, respectively. The analytical depth with this technique is estimated to be approximately 5-10 nm. The results are summarized in table 7.

TABLE 7Summary of surface chemical analyzes of titanium and coated surfaces controls (TiBi, TiNBi, TiGa, TiNGa). The values (% at) describe the elementary concentration ranges (n = 6). * The titanium signal (TiL) and the nitrogen signal (NK) are located nearby, which contributes to the variation in nitrogen concentration (N)

Surface analytical technique Detected elements Su coating surface Ti (uncoated) TiBi TiNBi TiGa TiNGa EDX You 83.4-84.6 72.4-93.1 58.4-73.2 98.9-99.5 58.9-59.2 N * 0-11.8 0-10.1 26.1-41.3 0-12.3 40.9-41.1 Bi - 5.9-12.6 0.2-0.7 - - Ga - - - 0.5-1.1 - XPS You 21.0-25.9 16.1-24.1 27.8-28.5 15.4-24.6 18.2-28.9 N 0.7-2.0 0-1.8 26.0-27.0 1.9-2.7 24.6-28.6 Bi - 1.9-3.3 0.2 - - Ga - - - 0.3-0.4 0.1-0.3 Ç 18.8-27.7 15.8-33.1 16.0-17.8 18.6-45.9 18.2-28.9 O 49.2-55.5 46.5-56.8 27.7-29.2 36.2-54.8 21.5-24.2

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b) Surface roughness [0112] The surface roughness of the specimens produced according to example 2A was measured with a surface profilometer (Hommel T1000 wave, Hommelwerke GmbH, Germany). A vertical measurement in the 320 pm range and a 4.8 mm length assessment were used. Three specimens of each type were included in the analysis, and three measurements per specimen were performed. The surface roughness in terms of values of the arithmetic mean of the vertical deviations of the roughness profile from the main line (Ra) was calculated after using a filtering process, with a cut-off point of 0.800 mm. The results are shown in table 8.

TABLE 8. Surface roughness (Ra) ± standard deviations (SD), n = 9.

Tested specimen Ra (pm) Uncoated titanium 0.23 (0.04) Titanium coated with TiBi 0.24 (0.05) Titanium coated with TiNBi 0.22 (0.03) Titanium coated with TiGa 0.23 (0.05) Titanium coated with TiNGa 0.23 (0.02)

c) Wettability [0113] In order to investigate the wettability of specimens produced according to example 2A, the contact angle was measured using a contact angle measurement system (Drop Shape Analysis System DSA 100, Kruss GmbH, Germany) . The measurements were performed with deionized water. The results showed that all specimens were hydrophilic (<90 °), although variations between specimens have been observed, see table 9.

TABLE 9. Contact angle (°) ± standard deviations (SD)

Tested specimen Contact angle (°) Uncoated titanium 63 (5) Titanium coated with TiBi 50 (6) Titanium coated with TiNBi 66 (5) Titanium coated with TiGa 41 (1) Titanium coated with TiNGa 59 (2)

EXAMPLE 2C. Gallium and bismuth release from surface coatings

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34/40 [0114] The release of gallium (Ga) or bismuth (Bi) from all surface coatings (TiBi, TiNBi, TiGa, TiNGa) was confirmed in the experiments. At a pH of 7.4 low amounts of Ga and Bi, respectively, were released, but at pH 5.0 the release of Bi increased significantly.

[0115] For all release experiments, specimens of commercially pure titanium (cp), titanium coated with TiBi, titanium coated with TiNBi, titanium coated with TiGa and titanium coated with TiNGa produced as described in example 2A were used. The release experiments were carried out by immersing the specimens in either a phosphate buffer (pH 7.4) or an acetate buffer (pH 5.0). The pH of 7.4 was intended to similar to a physiological neutral condition (pH 7.4). The acid pH (5.0) was intended similar to a condition that can occur locally in the tissue in the case of inflammation and / or infection. Glass bottles containing 10 ml of buffer were used with one specimen per bottle. The bottles were placed on a shaker at 37 ° C during the experiment. After 1, 4, 7, and 24 days, liquid samples were taken and the concentrations of Bi and Ga were analyzed using an inductively coupled plasma sector mass spectrometer (ICP-SFMS). The results are shown in table 10.

TABLE 10. Release of bismuth (Bi) or gallium (Ga) into an acetate buffer (pH 5.5) or phosphate buffer (pH 7.4). Figures mean values (n = 2), standard deviations within parentheses

Time (days) Release c and Bi (pg / l) Ga release (pg / l) Ti coated with Ti coated with TiNBi Ti coated with TiGa Coated Ti You Bi with T fiNGa pH 5.0 pH 7.4 pH 5.0 pH 7.4 pH 5.0 pH 7.4 pH 5.0 pH 7.4 1 2840 (240) 16.2 (0.1) 1150 (28) 3.6 (0.2) o o -> íO • s— · ' 1.3 (0.1) 8.4 (1.4) 11.9 (1.2) 4 3225 (21) 25.6 (7.9) 1660 (806) 3.9 (1.2) o o '-J. Aj •s-·' 1.3 (0.2) 12.7 (0.4) 12.4 (1.7) 7 2700 (141) 22.9 (1.6) 1470 (438) 2.6 (0.3) o o '-J. Aj •s-·' 1.6 (0.1) 13.3 (2.1) 12.4 (0.4) 24 - 10.3 - 8.3 - 2.1 14.7

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(0.1) (2.0) (0.3) (0.9)

EXAMPLE 2D. ANTIMICROBIAL EFFECT OF METAL OR NITRET COATED SPECIMENS [0116] A titanium body having a surface comprising gallium (Ga) or bismuth (Bi) in the form of TiGa, TiNGa, TiBi or TiNBi has been found to prevent the growth of Pseudomonas aeruginosa and Staphylococcus aureus on a surface and thus can be useful in preventing harmful infection around, for example, the dental pivot implanted in the gums.

a) Antimicrobial effect of bismuth (Bi) and gallium (Ga) against different species of bacteria [0117] The depletion and characterization plates by gram stain were made. MRSA and PA01 were grown on tryptic soy agar (TSA) plates and S. sanguinis on horse blood plates for up to 24 hours while P. gingivalis was grown between 4 and 5 days on restricted anaerobic agar (FAA) plates . A five-fold dilution in at least five stages of gallium nitrate (Ga (NO3) 3) or bismuth chloride (BiCb) was made. The bismuth salt had to be suspended in DMSO in order to allow the salt to dissolve in a culture medium.

[0118] Equal amounts of bacterial solution and antimicrobial salt (in five-fold dilution) were mixed and incubated at 35 ± 2 ° C: MRSA, PA01, and S. sanguinis for 24 hours and P. gingivalis for 4 or 5 days. After incubation, the concentration where no visual growth could be detected was documented. The results are summarized in table 11.

TABLE 11. Minimum inhibitory concentration values in pg / ml.

* The MIC values were different in the three different runs, so the MIC values from all runs are included.

MRSA PA01 S. sanguinis P. gingivalis Ga (NO3) 3 (Mg / ml) 1000 200 1000 40 BiCl3 (pg / ml) 20 * 900 * 20 * 900 * 40 1000

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40 * 200 *

[0119] MIC values indicate that both Ga and Bi have an antibacterial effect against several species of bacteria, although the effect varies for different species. The variation in MIC values for BiCl3 against MRSA and PA01 was probably caused by the inadequate dissolution of BiCl3 (high values indicating that the salt was not completely dissolved and was therefore unavailable for inhibition).

b) Inhibition of bacterial growth using a film contact method [0120] In another experiment, a film contact method (Yasuyuki et al, 2010) was used. The depletion plates of Pseudomonas aeruginosa (PA01) were made and 1 colony was inoculated to 5 ml of triptych soy broth (TSB) in culture tubes and grown under stirring conditions for 18 hours. Cell density was measured on a spectrophotometer at OD 600 nm and counted using a cell counting chamber. The cell culture was adjusted with sterile TSB to 1-5 X 10 ⁶ cells / ml. Specimens of commercially pure titanium (cp) coins (0 6.25 mm) and cp titanium coins with TiBi, TiNBi, TiGa or TiNGa coating were prepared aseptically and placed in the respective wells of a 12-well plate. A thin transparent plastic film was perforated, and sterilized using 70% ethanol and UV irradiation on each side. A 15 μl drop of bacteria in TSB was applied to each specimen. A thin plastic film per specimen was placed over the bacteria in the specimens so that the bacterial solution was spread evenly over the specimen's surface, ensuring good contact. After incubation for 24 hours at 30 ± 1 ° C, the film of each specimen was removed aseptically and washed by pipetting 1 ml PBS on the surface in a 2 ml eppendorf tube separated by specimen. The specimens were transferred to the same eppendorf tubes used when the films were washed. First, the surface of each specimen was washed by pipetting the same PBS with which the film

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37/40 was previously washed. Then, the specimens were sonicated and for 1 minute and vortexed vigorously for 1 minute in the same tubes used before when the film was washed. Serial dilutions and plate counting were performed. The plates were incubated for 24 hours and the numbers of colonies counted and recorded. The antibacterial activity of titanium specimens coated with TiBi, TiNBi, TiGa, or TiNGa was determined to be> 99.5% reduction against PA01 compared to titanium, see table 12.

TABLE 12. Antibacterial activity was calculated as a percentage reduction (compared to uncoated titanium) after 24 hours of incubation of the specimens tested against Pseudomonas aeruginosa (PA01).

Tested specimens Reduction of PA01 (%) Titanium coated with TiBi 99,804 Titanium coated with TiNBi 99.998 Titanium coated with TiGa 99,551 Titanium coated with TiNGa 99,524

EXAMPLE 2E. CITOTOXITY OF SPECIMENS COATED WITH

METAL OR NITRET [0121] All surface coatings (TiBi, TiNBi, TiGa, TiNGa) have been discovered to increase the mitochondrial activity of fibroblasts, that is, the viability of the cell, compared to uncoated titanium surfaces, using a cytotoxicity.

[0122] Cytotoxicity was assessed with a (3- (4,5-dimethylthiazol-2-yl) -5 (3-carboxymethoxyphenyl) -2- (4-sulfophenyl) -2H-tetrazolium (MTS) assay using human fibroblasts ( MRC-5). An MTS assay measures mitochondrial activity in cells and correlates with cell viability / number. For cytotoxicity experiments, specimens of commercially pure titanium (cp), titanium coated with TiBi, titanium coated with TiNBi , TiGa-coated titanium and TiNGa-coated titanium produced as described in example 2A as used.

[0123] The cells were subcultured according to the guidelines of the

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American Type Culture Collection. They had reached approximately 80% confluence when used in the experiment. Six coins of each specimen were placed aseptically on a 24-well plate, 1 coin per well. 100 pl of MRC-5 cells at 1x10 ⁵ cells / ml were added to each disc and controls. The plates were then incubated for one hour to allow attachment of the cell before 1 ml of complete cell culture medium was added to each well. The plates were then incubated for 24 hours before analysis. For the MTS assay, 4 coins of each specimen were transferred from the 24-well plates to the 48-well plates. 500 µl of MTS assay reagent was added to each well and incubated for 4 hours. The absorbance was then read at 490 nm. The absorbance values for each specimen were normalized for the control of uncoated titanium in the percentage configured to 100% (Table 13).

[0124] The remaining 2 coins from each specimen were used for DAPI staining and fluorescence microscopy to verify the result of the MTS assay. DAPI is a fluorescent dye that binds to the cell nucleus and can thus be used to visualize cells in metals.

TABLE 13. Mitochondrial activity (ie, viability) measured with an MTS assay for human fibroblasts cultured in coated and uncoated titanium specimens. Mean values, standard deviations within parentheses

Tested specimens Percentage of mitochondrial activity compared to uncoated titanium (Uncoated Ti = 100%) Titanium coated with TiBi 932 (118) Titanium coated with TiNBi 204 (21) Titanium coated with TiGa 136 (9) TiNGa coated titanium 179 (14)

[0125] In conclusion, it has been experimentally demonstrated that the surface layer comprising a post-transition metal compound, here a gallium, bismuth, or both compound, can be applied to a biocompatible metal (titanium) substrate to provide antimicrobial effect against various

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39/40 species of bacteria. It has also been shown that there is a release of post-transition metal from the surface layer under physiologically neutral conditions. Furthermore, in acidic conditions, which can occur very locally in the tissue in the case of inflammation / infection, the release of the post-transition metal can even be significantly increased. Finally, the tested surface layers are non-toxic to human fibroblast cells and can actually increase the mitochondrial activity of the fibroblast.

[0126] One skilled in the art realizes that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0127] Additionally, variations to the disclosed modalities can be understood and performed by a technician in the subject of the claimed invention, from a study of the drawings, the disclosure, and the attached claims. In the claims, the word "comprising" does not exclude other elements or steps and the indefinite article "one" or "one" does not exclude a plurality. The mere fact that certain measures are recited in claims dependent on different mutuality does not indicate that the combination of these measures cannot be used to advantage.

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Claims (25)

1. Dental implant intended for contact with a living tissue CHARACTERIZED by the fact that it comprises a substrate having a surface layer comprising one or more compounds of a non-toxic post-transition metal and titanium. 2. Dental implant, according to claim 1, CHARACTERIZED by the fact that said living tissue is a soft tissue. 3. Dental implant, according to claim 1 or 2, CHARACTERIZED by the fact that said surface layer is a metallic layer and said compound of a non-toxic post-transition metal is a metallic compound. 4. Dental implant, according to any of claims 1 to 3, CHARACTERIZED by the fact that said non-toxic post-transition metal is selected from bismuth and gallium. 5. Dental implant according to any one of claims 1 to 4, CHARACTERIZED by the fact that said compound of a non-toxic post-transition metal is selected from the group consisting of gallium-titanium, gallium-titanium oxide and gallium nitride -titanium. 6. Dental implant according to any one of claims 1 to 5, CHARACTERIZED by the fact that said compound of a non-toxic post-transition metal is selected from the group consisting of bismuth-titanium, bismuth-titanium oxide and nitride of bismuth-titanium. 7. Dental implant, according to claim 1, CHARACTERIZED by the fact that said non-toxic post-transition metal compound comprises gallium and bismuth and titanium. 8. Dental implant according to any of claims 1 to 7, CHARACTERIZED by the fact that said post-transition metal compound does not Petition 870190071982, of 07/28/2019, p. 59/63 2/3 toxic to be a nitride. 9. Dental implant, according to claim 8, CHARACTERIZED by the fact that said nitride is selected from the group consisting of gallium-titanium nitride, gallium nitride, bismuth-titanium nitride, bismuth nitride and gallium-nitride bismuth-titanium. 10. Dental implant according to any one of claims 1 to 9, CHARACTERIZED by the fact that said compound of a non-toxic post-transition metal constitutes the major part of said layer. 11. Dental implant, according to any one of claims 1 to 10, CHARACTERIZED by the fact that it still comprises a non-toxic postransition metal salt deposited on said surface layer. 12. Dental implant according to any one of claims 1 to 11, CHARACTERIZED by the fact that said surface layer has a thickness in the range of 10 nm to 1.5 pm. 13. Dental implant, according to any one of claims 1 to 12, CHARACTERIZED by the fact that said layer is a homogeneous layer. 14. Dental implant according to any one of claims 1 to 13, CHARACTERIZED by the fact that said layer is a non-porous layer. 15. Dental implant according to any one of claims 1 to 14, CHARACTERIZED by the fact that said substrate comprises a metallic material, preferably titanium or titanium alloy. 16. Dental implant according to any one of claims 1 to 14, CHARACTERIZED by the fact that said substrate comprises a ceramic material. 17. Dental implant according to any one of claims 1 to 14, CHARACTERIZED by the fact that said substrate comprises a polymeric material. 18. Dental implant according to any one of claims 1 to 14, CHARACTERIZED by the fact that said substrate comprises a composite material. Petition 870190071982, of 07/28/2019, p. 60/63 3/3 19. Dental implant, according to any one of claims 1 to 18, CHARACTERIZED by the fact that it is an implant intended for contact with a living tissue for a duration of more than 30 days. 20. Dental implant according to any one of claims 1 to 18, CHARACTERIZED by the fact that it is intended for contact with a living tissue for a duration of more than 24 hours up to 30 days. 21. Dental implant according to any one of claims 1 to 18, CHARACTERIZED by the fact that it is intended for contact with living tissue for a duration of less than 24 hours. 22. Dental implant, according to claim 21, CHARACTERIZED by the fact that said dental implant is a dental pivot. 23. Method for producing a dental implant, as defined in any of claims 1 to 22, CHARACTERIZED by the fact that it comprises: a) providing a substrate having a surface; and b) applying a compound of a non-toxic post-transition metal and an additional metal or metal compound comprising titanium on said surface to form a layer. 24. Method, according to claim 23, CHARACTERIZED in that said compound of a non-toxic post-transition metal is a nitride of a non-toxic post-transition metal, preferably a gallium and / or bismuth nitride. 25. Method, according to claim 23 or 24, characterized by the fact that step b) is performed using a thin film deposition technique.