WO2017009500A1

WO2017009500A1 - Dental abutment for retaining removable dental prostheses on implants and abutment and retention element assembly

Info

Publication number: WO2017009500A1
Application number: PCT/ES2016/070426
Authority: WO
Inventors: Jordi TERRATS BES; Ramon TERRATS BES
Original assignee: Terrats Medical, S.L.
Priority date: 2015-07-15
Filing date: 2016-06-07
Publication date: 2017-01-19
Also published as: ES2597153B1; ES2597153R1; ES2597153A2

Abstract

The dental abutment for retaining removable dental prostheses on implants comprises a body whose first end is provided with connection means for connecting to an implant and whose second end is configured for the coupling thereof to a removable dental prosthesis by way of an interlocking piece housed in a cavity of the prosthesis. The abutment, at least at the second end of the body which can contact the interlocking piece, is covered externally with a zirconium nitride coating, the surface roughness of the second end on which the coating is applied being lower than or equal to Ra 0.3 µm.

Description

D E S C R I P C I Ó N

Dental attachment for the retention of removable dentures on implants and attachment assembly and retention element

Technical sector of the invention

The present invention relates to a dental attachment for the retention of removable dentures on implants. This type of attachment is also called a retention pillar. The attachment is one of those comprising a body whose first end is provided with connection means for connection to an implant. The second end of the body is configured for coupling to a removable dental prosthesis through an interlocking piece, which in turn is intended to be housed in a cavity arranged in the prosthesis. The interlocking part is provided with a retention element that in an operative retention position of the prosthesis remains in contact with the second end of the attachment body.

The invention also relates to an assembly formed by the attachment object of the invention and by at least one retaining element.

Background of the invention

It is widely known that to replace missing teeth or complete dentures, the use of dental implants, which mostly consist of a metal part, usually made of titanium due to its osseointegration capacity, anchored to the jaw bone is used or maxilla of the patient. Dental implants, whether complete or partial, are held on implants and by various techniques.

One of the usual techniques is the so-called "removable prosthesis" solution, which means that the patient himself, without the intervention of any professional, is able to remove and replace his dental prosthesis. Over time, the technique has evolved in terms of the method for the achievement of that result.

At the beginning, and still today in some cases, a type of implants known as ball implants was used, designed for cases in which only the option that the prosthesis was removable was contemplated. Subsequently, the design options of the attachments were expanded, being able to be screwed onto conventional implants, and therefore became removable with respect to the implants. Another application of the removable prosthesis attachments or abutments occurs when a fixed screwed prosthesis must be replaced or repaired. Then, and provisionally, the patient can use a removable prosthesis, for which, in the clinic the usual one is disassembled and two or more pillars are mounted to provisionally anchor the removable prosthesis while the definitive prosthesis is repaired, modified or replaced.

However, today it has practically ended up imposing a certain geometry that several manufacturers share. Thus, this type of attachment is commonly provided with a thread that is screwed by the first end of the attachment to the osteointegrated implant in the jaw or jaw of the patient.

At the opposite end, the body of the attachment, more or less long, has a slight circular protrusion at the apical end, intended to be inserted into an interlocking piece provided with a "female" type socket. Thus, the retention is effected by exerting a pressure of the prosthesis on the blocking abutments or attachments. The prosthesis itself is equipped with cavities, where the interlocking pieces are housed which in turn are configured internally with a "female" socket to fit the pillars in question. These interlocking pieces commonly consist of two parts, a metal in the shape of a bowl, and the other of a plastic material, called a retention element, which is the one that elastically deforms and holds the second end of the attachment or retention pillar captive. The plastic material of the retention element used is usually nylon. It has been found that after several operations of placing and removing the removable prosthesis from the abutment, as well as by the use of the prosthesis by the person wearing it (for example during chewing), the retention element suffers considerable deterioration which forces having to frequently replace a retention element with a new one.

Thus, the need to minimize wear of the retaining elements during their coupling to the attachments or abutments described above is revealed.

Explanation of the invention.

In order to provide a solution to the problems raised, a dental attachment for the retention of removable dentures on implants, also known as a retention abutment, is disclosed. The dental attachment comprises a body whose first end is provided with connection means for connection to an implant, and whose second end is configured for coupling to a removable dental prosthesis through an interlocking piece. In turn, the interlocking piece is intended to be housed in a cavity of the prosthesis and is provided with a retaining element that, in an operative retention position of the prosthesis with respect to the attachment, remains in contact with the second end of the body of the attachment.

In essence, the dental attachment is characterized in that the second end of the body that is capable of contacting the retaining element of the interlocking piece is covered externally by a coating of zirconium nitride, ZrN, the average surface roughness value being of the second end on which the coating less than or equal to Ra 0.3 μι ι is applied.

It should be mentioned that the zirconium nitride coating is biocompatible, that is, it can be in contact with body tissues without presenting allergic, immune reactions, etc. to be biologically inert.

In this way, the technical coating of zirconium nitride is specifically applied at least on the visible part of the attachments or abutments intended for the retention of removable dentures on dental implants. This type of attachment is commonly provided, at the first end of its body, with connection means consisting of an externally threaded portion, as a threaded rod, which is screwed to the osteointegrated implant in the jaw or maxillary bone of the patient, and at the second apical end of a curved convex surface protrusion that protrudes laterally from the rest of the body, which is generally cylindrical. This protrusion located at the second apical end is intended to be coupled to the interlocking part when it is held by the retaining element provided in said part. It is precisely on this protuberance where the zirconium nitride coating is applied, although also preferably the coating extends to the cylindrical part of the body of the attachment.

According to other features of the invention, the zirconium nitride coating has a nanodure of 2800 ± 300 HV and a friction coefficient of approximately 0.5 f on dry steel. In addition, the zirconium nitride coating is monolayer and preferably has a thickness between 2.0 μηι and 3.0 μηι.

It is known that the retention elements that are part of the interlocking parts that are fixed to the prostheses are made of plastic, usually of nylon, so they tend to degrade quickly if we take into account that in each operation, to allow entry from the second end of the attachment in the interlocking pieces, the retaining elements must be elastically deformed, then recover their initial shape and dimensions. Usually the retention elements are in the form of a closed ring, so the material must be relatively soft to be able to deform, and this lack of consistency makes these nylon retention elements prone to permanent deformations caused by unfortunate coupling maneuvers. The zirconium nitride coating provided at least at the second end of the attachment, provides the best functional conditions due to its excellent coefficient of friction and low roughness in the contact area between the attachment and the retention element, which is what has of supporting the relative movements and efforts during the normal operation of the prosthesis by the person and during the coupling and uncoupling of the attachment-implant assembly with respect to said removable prosthesis anchored to the jaw. The fact that the zirconium nitride coating is applied on the second end of the attachment and that it is already a highly polished surface, with a surface roughness less than or equal to Ra 0.3 μηι, combined with the surface hardness and The low coefficient of friction of the coating itself, allows to prolong the life of the plastic retention elements.

In addition to the mechanical advantages set out above, the area of the zirconium nitride-coated attachment acquires a very aesthetic yellow color, due to its better visual result through the opalescence of the ceramic elements that constitute the prostheses that constitute they are placed on the attachments, and on the material of the artificial gum

According to another feature of the invention, the zirconium nitride coating has a temperature resistance between 580 and 600 ° C. Preferably, the zirconium nitride coating is applied on the surface of the second end of the body of the attachment by physical vapor deposition.

According to another characteristic of the attachment object of the invention, and as previously introduced, the connection means provided by the first end of the attachment for connection to an implant are configured as an externally threaded portion or stem according to the thread thread that It has an internally threaded hole provided in the implant head. According to another characteristic of the attachment object of the invention, the material of the body of the attachment is metallic, preferably titanium.

Preferably, the body of the attachment is formed by a body of revolution comprising at least one intermediate section of cylindrical outer surface between the first end and the second end.

According to another characteristic of the attachment object of the invention, the second end of the body comprises an apical protuberance of curved-convex lateral surface protruding laterally from the intermediate section of cylindrical external surface. Preferably, the apical protuberance of the second end of the attachment body is configured as a curved-convex surface or as a flat surface joined to the rest of the attachment body by curved-convex edges, protruding laterally from the rest of the attachment body, that is, protruding laterally with respect to the cylindrical surface that forms the section of body that follows the apical protuberance.

According to another characteristic of the attachment object of the invention, the zirconium nitride coating partially or totally covers the surface of the body of the attachment, that is, in addition to covering the apical protrusion of the second end, that is, the area that contacts the retaining element of the interlocking part in the operative retention position of the prosthesis by the attachment, the zirconium nitride coating can be extended to the rest of the body of the attachment also covering the cylindrical outer surface of the intermediate section.

According to another embodiment of the attachment of the invention, referred to herein as a second embodiment, the cylindrical outer surface of the intermediate section of the attachment is covered by the zirconium nitride coating described above but also, on this first coating the intermediate section comprises a second coating for Biomedical applications, rich in ΤΊΟ2 porous, comprising pores with a diameter and / or a depth of less than 50 nm. Referring to the second coating being rich in ΤΊΟ2, it should be understood that an essential part of the second coating is ΤΊΟ2, generally more than 50% by weight of the composition of the second coating. Preferably, more than 70% by weight of the composition of the second coating is ΤΊΟ2, and even more preferably it represents more than 90% by weight.

The material of the second coating had previously demonstrated its ability as a coating to improve adhesion between an implanted biomaterial and the surrounding soft tissue when the coated material belonged to the group consisting of titanium, nitinol, ceramic and polymeric material and any combination thereof. However, tests carried out by the inventors have shown that their capacity is maintained when applied on the zirconium nitride layer of the first coating. In this way, not only the mechanical performance of the attachment is improved, causing soft tissue adhesion, such as the gum and mucosa, to the intermediate section of the cylindrical external surface of the attachment or prosthetic abutment. From the clinical point of view, it is accepted by independent notified bodies that allows faster healing of surgery, reduces inflammation, reduces bone loss and achieves soft tissue adhesion, and is also expected to impact favorably in reducing cases of perimplantitis.

According to another characteristic of the second embodiment, an essential part of the pores of the second coating is constituted by pores having a diameter of 2 to 50 nm and a depth of at least 1 nm.

According to another characteristic of the second embodiment, the second coating is obtainable by a process comprising the following steps:

a) prepare a sun of ΤΊΟ2, S1O2 or TIO2-S1O2;

b) aging said sun;

c) contacting the surface of the intermediate section coated with the first zirconium nitride coating with said sun having said sun prepared in stage a) and aged in stage b) in which said contacting is optionally carried out by immersing said surface in said sun; d) removing said surface from said sun at a predetermined speed to obtain a second coated surface if said contacting of step c) has been carried out by immersing said surface in said sun;

e) optionally heat treating the second coated surface for a predetermined time;

f) optionally clean the second coated surface;

g) optionally drying the second coated surface; Y

h) repeat at least steps c) and d), but optionally also some of steps a) to g), a number of times to obtain the desired number of second coating layers if more than one second coating layer is desired on the intermediate section of the attachment. According to another characteristic of the second embodiment, step a) of preparing the sun comprises the following steps:

(i) dissolve tetraisopropyl orthotitanate Ti ((CH3) 2CHO) 4 and / or tetraethyl orthosilicate in ethanol,

(ii) dissolve the ethylene glycol monoethyl ether (C2H50CH2CH20H), deionized water and hydrochloric acid or nitric acid in ethanol, and

(iii) mix the solutions obtained in step (i) and (ii) and optionally stir said mixture effectively.

According to another characteristic of the second embodiment, the sun is at a cooled temperature of -10 to + 20 ° C, preferably -5 to + 5 ° C, even more preferably -2 to + 2 ° C during step c).

According to another characteristic of the second embodiment, the sun prepared in stage a) is aged in stage b) for 1 min to 10 days, preferably for 1 to 48 hours.

According to another characteristic of the second embodiment, the surface of the intermediate section coated with the first zirconium nitride coating is brought into contact with the sun by immersing it in the sun in step c) and is removed from the sun in step d) at a speed of 0.01 mm / s to 10 mm / s, preferably at a speed of 0.1 mm / s to 1.0 mm / s.

According to another feature of the second embodiment, the surface is heat treated in step e) at a temperature of 200 to 600 ° C, preferably at a temperature of 375 to 425 ° C, and more preferably about 400 ° C. The zirconium nitride coating has a temperature resistance between 580 and 630 ° C so it is compatible with the heat treatment of step e).

According to another feature of the second embodiment, the heat treatment in step e) is carried out for 0.1 s to 10 days, preferably 1 s to 10 h, even more preferably 1 min to 1 h. According to another characteristic of the second embodiment, the second surface coated with the second coating or the layers of the second coating are ultrasonically cleaned in step f).

The second coating obtainable by the process described above generates on the surface of the first ZrN coating microcavities of nanometric dimensions, similar in size to the molecules that constitute the soft tissues, by which said tissues are induced to adhere to the coated surfaces by the second coating. When applying the second coating on the first ZrN coating, the soft tissues surrounding the intermediate section of the cylindrical outer surface of the attachment adhere to the second coating, reducing or minimizing the spaces between the attachment and the living tissue, avoiding or reducing the Possible foci of bacterial infection and retraction of the tissues themselves.

Alternatively to the indicated procedure, the second coating of the second embodiment of the attachment object of the invention is obtainable by a process comprising the following steps: a) prepare a simulated body fluid;

b) adding a source of Si and / or a source of solvent Ti to the simulated body fluid prepared in step a);

c) contacting the surface of the intermediate section coated with the first zirconium nitride coating with the mixture obtained in step b) in which said contacting is optionally carried out by immersing said surface in said mixture; Y

d) letting the solvent and / or Ti solvent based material form a coating as it is adsorbed and / or reprecipitated on the surface of said material.

According to this alternative procedure, the source of Si is bioactive glass or S1O2 derived from sol-gel. According to another characteristic of the alternative procedure, the simulated body fluid of step a) is a solution that mimics the body fluid or a buffered solution at the pH of the body fluid, with a pH of 7.2-7.4.

According to another feature of the alternative procedure, the simulated body fluid is SBF comprising 1.0-1.5 mM Mg ²⁺ , 1.6-2.5 mM Ca ²⁺ , 103-147.8 mM Cr and 4.2-27 mM of HCCV.

According to another aspect of the invention, the invention also relates to an assembly of an attachment as described above, according to any of its embodiments, and of at least one retention element made of polyether ether ketone, material also known as PEEK, configured to be placed in an interlocking piece whereby the attachment is coupled to a removable dental prosthesis. PEEK material is a sanitary fit and its mechanical behavior is much better in relation to the currently known nylon retaining elements.

According to a preferred embodiment of the assembly, at least one retaining element is shaped as an annular side wall cover adapted to embrace and cover at least the second end of the addition.

Also preferably, the annular side wall comprises at least two radial grooves or cuts that start from the lower edge of the side wall.

Brief description of the drawings

The attached drawings illustrate, by way of non-limiting example, three embodiments of the attachment object of the invention. In these drawings:

Fig. 1 is a view of a first embodiment of the attachment object of the invention partially sectioned by its axis of revolution;

Fig. 2 is a view of the attachment of Fig. 1, without sectioning, in the operative retention position with respect to the prosthesis in which the attachment is anchored through the retaining element of the interlocking part, showing the prosthesis, the interlocking part and the retaining element sectioned by a vertical plane comprising the axis of revolution of the attachment;

Fig. 3 is a view similar to that of Fig. 2 but with all the elements sectioned and in which the implant to which the attachment is connected is also shown;

Fig. 4 is a view of a second embodiment of the attachment object of the invention, in which the zirconium nitride coating not only covers the second end of the attachment but also the intermediate section of cylindrical outer surface;

Fig. 5 is a view of a third embodiment of the attachment object of the invention which, unlike the first embodiment, comprises a second coating on the zirconium nitride coating of the intermediate section of cylindrical surface;

Fig. 6 is a bottom view of a preferred embodiment of the retention element provided with four radial grooves or cuts;

Fig. 7 is a sectional view of the retaining element of Fig. 6 according to section A-A;

Fig. 8 is an image by AFM (atomic force microscope) of the surface of the zirconium nitride coating; Y Fig. 9 is an AFM image of the surface of the second coating.

Detailed description of the drawings

In Fig. 1 a dental attachment 1 is shown for the retention of the removable dental prosthesis 3 on implants 4. The attachment 1, also called the retention abutment, comprises a body whose first end is provided with connection means 1 1 , in an externally threaded stem, for connection to the threaded thread having an internally threaded hole provided in the implant head 4 osteointegrated in the jaw or maxillary bone of the patient or inserted in the gum 8 as shown in Fig. 3 As can be seen, the second end 12 of the attachment 1 is configured for coupling to the prosthesis 3 through an interlocking piece 5, in turn intended to be housed in a cavity arranged in the prosthesis 3. The interlocking part 5 it is formed by an inverted bowl-shaped metal piece 51 which in turn is provided inside with a retaining element 6. On the other hand, the second end 12 d the attachment 1 comprises in its apical zone a curved-convex outer surface protrusion that protrudes laterally from the rest of the body, which is generally cylindrical in shape (see intermediate section 14). This protuberance is intended to be coupled to the interlocking part 5 as it is held by the retaining element 6 provided in said part. This apical protuberance of the attachment 1 pressures into the interior space that forms the retention element 6. The side wall 61 of the retention element 6 will be elastically deformed to allow the attachment 1 to be retained inside, that is, the wall lateral 61 will move widening the interior space so that the second end 12 occupies said space and subsequently the lateral wall 61 will attempt to return to its initial shape and size by being in contact with the lateral surface of the apical protuberance in the operative retention position of the prosthesis 3 with respect to the attachment 1. The operative position is as shown in Figs. 2 and 3 As seen in Fig. 1, the second end 12 of the body of the attachment 1, that is, the area of the latter that contacts the retention element 6 in the operative retention position, is externally covered by a nitride coating 2 of zirconium, ZrN, the average surface roughness of the second end 12 being on which the coating less than or equal to Ra 0.3 μηι is applied. The surface morphology of this zirconium nitride 2 coating is shown in Fig. 8.

ZrN coating 2 is biocompatible, has a nanodure around 2800 HV and a friction coefficient of approximately 0.5 f calculated with respect to dry steel. In addition, the ZrN coating 2 is monolayer and preferably has a thickness between 2 μηι and 3 μηι. Due to its high hardness and low coefficient of friction, the ZrN coating 2 prevents premature deterioration of the retention elements 6, mostly made of plastic and specifically of nylon. The coating 2 of ZrN preserves in some way the degree of polishing that the attachment 1 has on the surface of its second end 12 on which it is applied, which continues to have a surface roughness of less than or equal to Ra 0.3 μηι on the surface. outer surface that forms the lining 2 of the attachment 1 of Fig. 1.

In addition to prolonging the life of the retention elements 6, the zone of the ZrN coated attachment 1 acquires a very aesthetic yellow color due to its better visual result through the opalescence of the ceramic elements.

The attachments 1 shown in Figs. 1, 3 and 4, are formed by a body of revolution comprising an intermediate section 14 of cylindrical outer surface that joins the second end 12 with the first end. In particular, in Fig. 4 it can be seen that the ZrN coating 2 covers not only the apical curved-convex protuberance of the second end 12 but also said intermediate section 14 cylindrical.

It should be mentioned that any of the attachments 1 shown are can be made available to the user together with a retention element 6 made of polyether ether ketone, that is, PEEK. PEEK material is a sanitary fit and its mechanical behavior is much better in relation to the currently known nylon retaining elements. With respect to said retaining element 6 in PEEK, its design may be identical or similar in shape to that shown in Fig. 1, that is, formed by an upper cover topped by an annular side wall 61 perimetrically continuous at its lower edge 63. However, advantageously, the annular side wall 61 of the retention element 6 comprises at least two radial grooves or cuts 62 that start from the lower edge 63 of the side wall 61, as for example can be seen in the retention element 6 of the Figs. 6 and 7 provided with four radial cuts 62 that start from the lower edge 63 and reach the part that constitutes the upper cover of the retention element 6. The resulting segments between two consecutive radial grooves or cuts 62 act as elastic springs in the maneuvers of placement / removal of the prosthesis 3.

With respect to Fig. 5, another embodiment of the attachment 1 is shown in which on the ZrN coating 2 covering the intermediate section 14 of cylindrical outer surface a second coating 7 is arranged for biomedical applications rich in ΤΊΟ2 and / or S1O2, and porous comprising pores with a diameter and / or a depth less than 50 nm. In addition, an essential part of the pores of the second coating 7 is constituted by pores having a diameter of 2 to 50 nm and a depth of at least 1 nm. The porous morphology of the second coating 7 can be seen in Fig. 9.

The second coating 7 is obtainable for example in the following manner (Peltola, Timo: Nanoscale Dimensions and in Vitro Calcium Phosphate Formation; Studies on Sol-gel-derived Materials and Bioactive Glass. Thesis, University of Turku, Turku, Finland, 2000) : Commercially pure Ti (quality 2) (cp) is used as the substrate material. Ti is milled with silicon carbide paper. Tetraisopropyl orthotitanate Ti ((CH3) 2CHO) 4 or tetraethyl orthosilicate sold in absolute ethanol (solution I) is dissolved. The ether ethylene glycol monoethyl (C2H5OCH2CH2OH), deionized water and smoking hydrochloric acid (HCI, 37%) or nitric acid is dissolved in ethanol (solution II). Solutions I and II mix and stir effectively. The sun prepared and ready for use is kept at 0 ° C in order to slow down the condensation reaction. The sun is maintained at 0 ° C during the wet coating process.

After 1 hour or 24 hours of aging, the second coating 7 is prepared by immersing at least the intermediate section 14 of the zirconium nitride coated attachment 1 in the sun and then removed at a speed of 0.30 mm / s. The intermediate section 14 of the resulting attachment 1 is heat treated (20-500 ° C) for 10 min. After heat treatment, the second coating 7 is ultrasonically cleaned in acetone for 5 min and in ethanol for another 5 min, and finally dried at room temperature. This immersion, heating and washing cycle is repeated as many times as necessary, depending on the number of coating layers 7 desired. Said sol may optionally contain one or more active or inactive agents such as drugs, mineralizing or antimicrobial agents (for example bioactive glass, sol-gel-derived ceramics, growth factors, preservatives, dyes, fluidity enhancers, binders or builders. the suspension that will be provided in the final coating The concentration of active agents in the sun of ΤΊΟ2 and S1O2 remains homogeneous during the immersion process.The second coating 7 is also biomimetically obtainable using an external source of Si and / or Ti for example as follows (Jokinen, Mika: Bioceramics by Sol-gel Method, Processing and Properties of Monoliths, Films and Fibers. Thesis, Abo Akademi University Torku, Finland, 1999): Si sources are in soluble S1O2-based materials under simulated body fluid conditions, such as bioactive glasses or S1O2 derived from sol-gel, intermediate section 14 of the Zirconium nitride coated attachment 1, which acts as a substrate, is placed in a solution containing the source of Si, where the solvent-based material S1O2 forms a coating as it is absorbed and / or reprecipitated on the substrate surface . The solution It is preferably a solution that simulates body fluid, such as SBF or buffered pH solutions (pH 7, 2-7, 4) of body fluid. Alternatively, the second coatings 7 can be produced accurately using the laser technique.

The CO2 laser operates in the infrared part of the spectrum at 10.6 μηι. The radiation is absorbed by solids derived titanium dioxide or silica gels. The substrate (the zirconium nitride coated attachment 1) is heated only locally and the second coating 7 can be selectively processed, allowing different areas of the same coating to have different properties. It is possible to control the degree of densification of the sol-gel derived coatings by selecting suitable treatment parameters such as laser power, laser beam transition speed and the focused laser beam spot size.

Using a computer-controlled movement stage during the treatment it is possible to produce second coatings 7 modeled on the attachments 1, to cover only certain areas thereof, such as only the intermediate section 14. A 1 mm sheet is often used. Ti thickness cp (quality 2) as substrate material. Ti substrate plates are submerged in the sun. Each layer is first heat treated in an oven, and then treated locally with CO2 laser (two 3 mm bands). The power ranges that can be used are 12-20 W. The distance between two adjacent laser scan lines can be maintained at 100 μηι. The movement speed can be 2.5 mm / s.

Alternatively, S1O2 ceramics can be mixed in polymeric materials that form Si-rich surfaces in aqueous media in the materials of the compound that work in a manner comparable to the coatings described above.

The second preferred coatings 7 of T1O2 and S1O2 were selected based on: (a) sol-gel coatings can be prepared in thin layers which makes it possible to coat small devices or parts thereof, such as for example the cylindrical outer surface of the intermediate section 14 of the attachment 1; (b) bioactive components, for example drugs, growth factors, can be added in the second coatings 7; (c) the second coatings 7 can be applied to porous surfaces and structures.

Claims

1. - Dental attachment (1) for the retention of removable dental prostheses (3) on implants (4), comprising a body whose first end is provided with connection means (1 1) for connection to an implant (4) ) and whose second end (12) is configured for coupling to a removable dental prosthesis (3) through an interlocking piece (5) intended to be housed in a cavity of the prosthesis (3), the part of which is provided with a retention element (6) that in an operative position of retention of the prosthesis (3) with respect to the attachment (1), remains in contact with the second end (12) of the body of the attachment (1), characterized in that the second end (12) of the body that is capable of contacting the retaining element (6) of the interlocking part (5), is externally covered by a coating (2) of zirconium nitride, the value of the average surface roughness of the second end (12) on which it is The coating less than or equal to Ra 0.3 μηι has been applied.

2. - Dental attachment (1) according to claim 1, wherein the coating (2) of zirconium nitride has a nanodure around 2800 ± 300 HV.

3. - Dental attachment (1) according to any one of the preceding claims, wherein the coating (2) of zirconium nitride has a friction coefficient of approximately 0.5 f with respect to dry steel.

4. - Dental attachment (1) according to any one of the preceding claims, wherein the zirconium nitride coating (2) is a monolayer coating.

5. Dental attachment (1) according to any one of the preceding claims, wherein the coating (2) of zirconium nitride has a thickness between 2.0 μηι and 3.0 μηι.

6. Dental attachment (1) according to any one of the claims above, in which the coating (2) of zirconium nitride has a temperature resistance between 580 and 600 ° C.

7. - Dental attachment (1) according to any one of the preceding claims, wherein the coating (2) of zirconium nitride is applied on the surface of the second end (12) of the body of the attachment by physical vapor deposition.

8. - Dental attachment (1) according to any one of the preceding claims, wherein the coating (2) of zirconium nitride is biocompatible.

9. - Dental attachment (1) according to any one of the preceding claims, wherein the connection means for connection (1 1) to an implant (4) are configured as an externally threaded rod according to the threaded thread an internally threaded hole provided in the implant head (4).

10. - Dental attachment (1) according to any one of the preceding claims, wherein the material of the body of the attachment is metallic, preferably titanium.

1 1. - Dental attachment (1) according to any one of the preceding claims, wherein the body of the attachment, with the exception of the connection means (1 1), is formed by a body of revolution comprising at least one section intermediate (14) cylindrical outer surface between the first end and the second end (12).

12. - Dental attachment (1) according to claim 11, wherein the second end (12) of the body is formed by an apical protuberance of curved-convex lateral surface protruding laterally from the intermediate section (14) of cylindrical external surface .

13. Dental attachment (1) according to claim 11 or 12, wherein the coating (2) of zirconium nitride also covers the external surface cylindrical of the intermediate section (14).

14. - Dental attachment (1) according to claim 13, wherein on the coating (2) of zirconium nitride of the intermediate section (14), the attachment (1) comprises a second coating (7) for biomedical applications rich in T1O2 and / or S1O2, and porous comprising pores with a diameter and / or a depth less than 50 nm.

15. - Dental attachment (1) according to claim 14, wherein an essential part of the pores of the second coating is constituted by pores having a diameter of 2 to 50 nm and a depth of at least 1 nm.

16. - Attachment (1) according to claim 14 or 15, wherein the second coating (7) is obtainable by a process comprising the following steps:

a) prepare a sun of ΤΊΟ2, S1O2 or TIO2-S1O2;

b) aging said sun;

c) contacting at least the surface coated with the first zirconium nitride coating (2) of the intermediate section (14) of the attachment (1) with said sun having said sun been prepared in step a) and aged in the stage b) wherein said contacting is optionally carried out by immersing said surface in said sun;

d) removing said surface from said sun at a predetermined speed to obtain on the intermediate section (14) a second coated surface if said contacting of step c) has been carried out by immersing said surface in said sun;

e) optionally heat treating the second coated surface for a predetermined time;

f) optionally clean the second coated surface;

g) optionally drying the second coated surface; Y

h) repeat at least steps c) and d), but optionally also some of steps a) to g), a number of times to obtain the desired number of layers of second coating (7) if more than one layer of second coating (7) on the intermediate section (14).

17. Dental attachment (1) according to claim 16, wherein the sun preparation stage a) comprises the following steps:

(ii) dissolve the ethylene glycol monoethyl ether (C2H50CH2CH20H), deionized water and hydrochloric acid or nitric acid in ethanol,

18. Dental attachment (1) according to claim 16 or 17, wherein the sun is at a cooled temperature of -10 to + 20 ° C, preferably -5 to + 5 ° C, even more preferably -2 to + 2 ° C during stage c).

19. - Dental attachment (1) according to any one of claims 16 to 18, wherein the sun prepared in stage a) is aged in stage b) for 1 min. at 10 days, preferably for 1 to 48 hours.

20. - Dental attachment (1) according to any one of claims 16 to 19, wherein the surface coated with the first zirconium nitride coating (2) of the intermediate section (14) of the attachment (1) is contacted with the sun submerging it in the sun in stage c) and it is removed from the sun in stage d) at a speed of 0.01 mm / s to 10 mm / s, preferably at a speed of 0.1 mm / s to 1, 0 mm / s

21. Dental attachment (1) according to any one of the claims

16 to 20, wherein the second coated surface is heat treated in step e) at a temperature of 200 to 600 ° C, preferably at a temperature of 375 to 425 ° C, and more preferably at a temperature of approximately 400 ° C.

22. Dental attachment (1) according to any one of claims 16 to 21, wherein the heat treatment in step e) is carried out for 0.1 to 10 days, preferably 1 to 10 h, even more preferably 1 min to 1 h.

23. - Dental attachment (1) according to any one of claims 16 to 22, wherein the second surface coated with the second coating (7) or the layers of the second coating (7) are ultrasonically cleaned in step f).

24. - Dental attachment (1) according to any one of claims 14 or 15, wherein the second coating (7) is obtainable by a method comprising the following steps:

a) prepare a simulated body fluid;

c) contacting the surface coated with the first zirconium nitride coating (2) of the intermediate section (14), with the mixture obtained in step b) in which said contacting is optionally carried out by submerging said surface in said mixture; Y

25. Dental attachment (1) according to claim 24, wherein the source of Si is bioactive glass or S1O2 derived from sol-gel.

26. - Dental attachment (1) according to claim 24 or 25, wherein the simulated body fluid of step a) is a solution that mimics the body fluid or a buffered solution at the pH of the body fluid, with a pH of 7, 2-7.4.

27. - Dental attachment (1) according to claim 24, wherein the simulated body fluid is SBF comprising 1.0-1.5 mM Mg ²⁺ , 1, 6-2.5 mM Ca ²⁺ , 103-147.8 mM Cr and 4.2-27 mM HCCV.

28. - Assembly of an attachment (1) and at least one retaining element (6), characterized in that the attachment (1) is that defined in any one of the preceding claims and because the at least one retention element (6 ) is made of polyether ether ketone, configured to be placed in an interlocking piece (5) whereby the attachment (1) is coupled to a removable dental prosthesis (3).

29. - Assembly according to claim 28, wherein the at least one retaining element (6) is shaped as a side wall cover

(61) annular adapted to embrace and cover at least the second end (12) of the attachment (1).

30. - Assembly according to claim 29, wherein the annular side wall (61) of the retaining element (6) comprises at least two radial grooves or cuts (62) that start from the lower edge (63) of the side wall ( 61).