Process for the preparation of an osseointegrative topography on a body made of titanium or a titanium alloy

Abstract

The present invention relates to a process for the preparation of an osseointegrative topography on a surface of a body made of titanium or a titanium alloy, the body being an endosseous implant or a part of an endosseous implant system. The process comprises the subsequent steps of a) etching the surface of the body with an etching solution comprising a mineral acid, whereby a microscopic topographical formation is provided, b) placing the body obtained in step a) into a packaging container, and c) treating the body placed inside the packaging container with an aqueous saline maturation solution comprising an oxidative agent, whereby sub-microscopic particulate structures are formed on the microscopic topographical formation, said sub-microscopic particulate structures extending in at least two dimensions to 1 μm at most. The process of the invention is characterized in that the maturation solution used in step c) is a solution of an oxidative agent selected from the group consisting of hydrogen peroxide, sodium nitrate and potassium nitrate as well as mixtures thereof, the concentration of the oxidative agent in the maturation solution being in a range of higher than 0.01 wt.-% and less than 1 wt.-% referred to the total weight of the maturation solution, and that the treatment of step c) is carried out at a temperature of above 40°C.

Description

[0001] Process for the preparation of an osseointegrative topography on a body made of titanium or a titanium alloy

[0002] The present invention relates to a process for the preparation of an osseointegrative topography on a body made of titanium or a titanium alloy, and to a body obtainable by this process , the body being an endosseous implant or a part of an endosseous implant system .

[0003] Endosseous implants , such as dental implants , are well known in the art . They generally consist of a material which is biocompatible , and which additionally has favourable mechanical properties . Currently used dental implants are often made of titanium or a titanium alloy, which apart from being biocompatible exhibit outstanding mechanical strength .

[0004] The acceptance of the human body towards an implant is determined by the implant surface . When detected as a foreign obj ect and re ected by the immune system, the implant may cause inflammation, which not only causes pain to the patient but often also leads to the necessity of a second surgery to remove or replace the implant .

[0005] In order to avoid rej ection of the implant by the human body, the implant surface must be engineered in a manner that cells attach to it and that natural body tissue , speci fically bone tissue or soft tissue , start growing around the implant .

[0006] In the case of a dental implant , for example , it is required that a direct structural and functional connection between living j awbone and the implant surface is achieved shortly after implantation . This is re ferred to in the art as

[0007] A24 067WO / 01 . 10 . 2025 "osseointegration" : a good osteointegration means that the implant safely ossi fies within a short healing time so that a permanent bond between implant and bone is obtained .

[0008] Besides the importance of the osseointegrative properties of the surface , there is increasing evidence that also a good interaction between the dental implant and the surrounding supracrestal connective tissue ( in the following referred to as the " soft tissue" ) is crucial for a success ful implantation . This is supported by the view that the soft tissue plays a fundamental role in establishing an ef fective seal between the oral environment and the endosseous part of a dental implant and, thus , also a barrier for bacteria to adhere on the soft tissue contact surface and the bone tissue contact surface of the implant .

[0009] The attachment of cells of the surrounding soft or bone tissue is governed by proteins which adhere , i . e . , adsorb, to the surface once the implant gets in contact with blood . It is assumed that the proteins adsorbed on the implant surface influence the behaviour, e . g. the di f ferentiation, of the cells of the respective tissue .

[0010] In order to achieve a fast and strong interaction between the dental implant and the respective tissue , adherence of these proteins on the surface is thus of paramount importance .

[0011] One important factor that influences protein adherence is the hydrophilicity of the surface .

[0012] In addition, the presence of speci fic nanostructures has been found to play an important role in the adherence of proteins .

[0013] In this regard, R .A. Gittens et al . (Biomaterials 32 ( 2011 )

[0014] A24 067WO / 01 . 10 . 2025 3395 - 3403 ) report on studies focussing on the hierarchical combination of both micro- and nanoscale roughness to promote osseointegration on clinically-relevant surfaces .

[0015] A speci fic process for providing structures for an improved protein adherence on the surface of a body, and particularly an implant , is described in WO 2013 / 056844 . The process comprises the step of storing an acid-etched basic body in an aqueous solution, by which nanostructures are formed on its surface . According to WO 2013 / 056844 , the process requires two weeks of storing until the nanostructures are completely developed .

[0016] In aiming at a topography exhibiting an improved adherence of proteins , WO 2016 / 189099 suggests a process involving a step, in which an acid-etched surface is treated with an aqueous solution comprising an oxidative agent for forming titanate- comprising sub-microscopic structures on the surface . In particular, WO 2016 / 189099 suggests a solution comprising a hydroxide of an alkali metal or of an alkaline earth metal for this treatment .

[0017] Despite WO 2016 / 189099 reporting on the formation of nanostructures favouring the speci fic adherence of proteins mediating blood coagulation and cell attachment in vi tro, there is an ongoing need for a surface resulting in an improved osseointegration in vi vo .

[0018] In this regard, a process would be desirable allowing improved osseointegrative properties to be provided to the surface within a relatively short time , in particular well before two weeks of storage , which is the preferred storing time taught in WO 2013 / 056844 .

[0019] A24 067WO / 01 . 10 . 2025 The obj ect to be solved by the present invention is therefore to provide a process , which allows a surface to be obtained exhibiting improved osseointegrative properties in vi vo and which allow this surface to be obtained within a relatively short period of treatment , and speci fically a treatment period shorter than two weeks .

[0020] The obj ect of the present invention is solved by the process according to claim 1 . Preferred embodiments of the invention are defined in the dependent claims .

[0021] According to claim 1 , the process of the present invention is directed to the preparation of an osseointegrative topography on a surface of a body in the form of an endosseous implant or a part of an endosseous implant system, in particular to a dental implant or a dental implant abutment . The body is made of titanium or a titanium alloy, i . e . the most common material used for dental implants or dental implant abutments .

[0022] The process comprises the subsequent steps of a ) etching the surface of the body with an etching solution comprising a mineral acid, whereby a microscopic topographical formation is provided, b ) placing the body obtained in step a ) into a packaging container, and c ) treating the body placed inside the packaging container with an aqueous saline maturation solution comprising an oxidative agent , whereby sub-microscopic particulate structures are formed on the microscopic topographical formation, said sub-microscopic

[0023] A24 067WO / 01 . 10 . 2025 structures extending in at least two dimensions to 1 gm at most .

[0024] According to the invention claimed, the maturation solution used in step c ) is a solution of an oxidative agent selected from the group consisting of hydrogen peroxide , sodium nitrate and potassium nitrate as well as mixtures thereof , the concentration of the oxidative agent in the maturation solution being in a range of higher than 0 . 001 mol / dm3and less than 0 . 1 mol / dm3. In addition, the treatment of step c ) is according to the invention carried out at a temperature of above 40 ° C .

[0025] It has surprisingly been found that by the process of the present invention, a surface is obtained, which in vi vo exhibits improved osseointegrative properties . In particular, biomechanical pull-out force experiments in a rabbit model have revealed comparable osseointegration as for SLActive® implants , and improved osseointegration as compared to the one of a surface subj ected to a short-time treatment using an aqueous solution falling outside the scope of the claim .

[0026] Notably, SLActive® implants require a long storage period of more than 14 days for growth of nanostructures comparable to the ones obtained by the present invention . This period can be shortened substantially when treating the body according to the present invention .

[0027] Hence , the process of the present invention allows a surface of highly osseointegrative properties to be provided in a much shorter period than it is the case for SLA® and SLActive® implants , which ultimately leads to a substantial decrease in the production time of the implant and thus in the prevention of delays in the delivery timeline .

[0028] A24 067WO / 01 . 10 . 2025 The term "sub-microscopic particulate structures" as used in the context of the present invention is to be interpreted broadly and relates to any particulate structure, more particularly crystalline structure, which extends in at least two dimensions to 1 pm at most. The term is equivalent to the term "sub-micron structures". Although the structures are typically crystalline, this has not necessarily to be the case. Hence, structures, which are partially crystalline, but not solely crystalline, are also encompassed by the term "sub- microscopic particulate structures".

[0029] Without wanting to be bound by the theory, the effect of improved cell attachment can be explained by the following mechanism:

[0030] When a body is implanted into tissue, particularly into bone tissue, it is first contacted by water molecules from the surrounding blood. In a next step, ions and proteins will accumulate and adhere on the implant's surface, but without actually penetrating the material. This "protein adherence" or "protein adsorption" is assumed to be decisive for later cell responses .

[0031] By the specific topography obtainable by the present invention featuring the sub-microscopic particulate structures referred to above, protein retention structures are provided on the body's surface, i.e. structures which allow an improved adherence of specific proteins governing the interaction between the implant and the surrounding tissue.

[0032] Given the formation of sub-microscopic particulate structures in step c) , the process of the present invention is in any respect different from the technology described in "Alkali

[0033] A24067WO / 01.10.2025 Treatment of Microrough Titanium Surfaces Af fects Macrophage / Monocyte Adhesion, Platelet Activation and Architecture of Blood Clot Formation" by V . Milleret et al . , European Cells and Materials Vol . 21 2011 , pp 430-444 , describing the treatment of a titanium surface in a manner that the surface topography is not af fected .

[0034] In view of the particulate nature of the sub-microscopic structure obtained, the present invention is also in contrast to methods involving nanopitting, as e . g . described in US 2011 / 233169 .

[0035] The present invention is also in clear contrast to any process devoid of step a ) , i . e . any process in which no etching is performed, as it is the case for the process described in WO 2009 / 024778 . Notwithstanding the mechanism described above , according to which proteins accumulating and adhering on the surface put the surface in an improved condition for later cell response , topographical features as received by etching the surface in step a ) of the present invention have nevertheless been found to form an essential basis for achieving good osteointegration .

[0036] By using an aqueous solution containing the oxidative agent at a relatively low concentration, the present invention is in further contrast to what is taught in WO 2016 / 189099 discussed above , and in KR 2003- 0038631 disclosing a surface treatment using a H2O2 solution in a concentration of 15% to 30% . In particular in light of these documents , the finding that a very beneficial surface treatment can be achieved by using a maturation solution containing the oxidative agent at a relatively low concentration, has been most surprising . The

[0037] A24 067WO / 01 . 10 . 2025 concentration of oxidative agent being low brings the additional advantage that the implant can, after the treatment for forming the sub-microscopic structure , remain in the maturation solution for further storing . This is di f ferent to the situation when an aqueous solution of a relatively high concentration of H2O2 is used, requiring the practitioner to rinse the implant thoroughly prior to implantation for removing H2O2 and preventing it from exerting a disinfecting ef fect .

[0038] Thus , the present invention allows to circumvent the additional step of removing the implant from the maturation solution and placing it into an additional container filled with a di f ferent solution for final storage . This also contributes to a fast and simple workflow in the production process of the implant without compromising its osseointegrative properties .

[0039] As mentioned above , sub-microscopic particulate structures obtained in step c ) are formed on the microscopic topographical formation obtained in step a ) . Thus , a formation of di f ferent topographical scale is formed in step c ) than in step a ) , leading to a hierarchical topography of the body .

[0040] Typically, a layer comprising or essentially consisting of the sub-microscopic particulate structures is formed in step c ) . Speci fically, the layer has a thickness of more than 10 nm, which is apparent from the fact that no metallic titanium signal is detected by X-ray photoelectron spectroscopy (XPS ) . The layer is thus thicker than an oxide layer spontaneously formed on titanium surfaces in the presence of air .

[0041] Unlike step c ) , which is an additive process step, step a ) is a subtractive process step . The process of the present invention, thus , includes the removal of material from the

[0042] A24 067WO / 01 . 10 . 2025 body in step a) , combined with the addition of material in step c) .

[0043] As will be further discussed in detail below, subtractive process step a) preferably corresponds to the acid etching according to the well-known SLA® treatment. Specifically, step a) , thus, relates to a pre-treatment comprising a mechanical subtractive treatment, more particularly a sand-blasting treatment, prior to the etching.

[0044] According to a preferred embodiment of the present invention, the microscopic topographical formation is defined by at least one of the following surface parameters: i) Sabeing the arithmetic mean deviation of the surface in three dimensions and being in the range from 0.1 pm to 2.0 pm, preferably being in a range from 0.4 pm to 1.8 pm, more preferably from 0.8 pm to 1.5 pm, and most preferably from 1.0 pm to 1.2 pm; ii) St being the maximum peak to valley height of the profile in three dimensions and being in the range from 4.0 pm to 12.0 pm, preferably being in a range from 6.0 pm to 10.0 pm, and most preferably from 7.0 pm to 9.0 pm; and / or iii) Sat being the skewness of the profile in three dimensions and being in the range from -0.6 to 1.0, preferably from -0.4 to 0.6, more preferably from -0.3 to 0.5.

[0045] The surface parameters are known to the skilled person and are analogue parameters for three dimensions to the parameters Ra, Rt and RSk, respectively, defined in EN ISO 4287, specifically

[0046] A24067WO / 01.10.2025 ISO 4287:1997, for two dimensions. More specifically, the above values relate to the values as e.g. obtainable by the WinSAM software (SAM (Surface Analysis Method) for Windows) known to the skilled person.

[0047] The above values for Sa, St and Sst relate in particular to a bone contacting surface of the body, i.e. a surface area located such on the body, specifically the implant, to come into contact with bone tissue after implantation. For a soft tissue contacting surface of the body, the preferred values are smaller. Specifically, Sais preferably in the range from 0.05 pm to 0.5 pm, more preferably from 0.05 pm to 0.3 pm for a soft tissue contacting surface.

[0048] As mentioned, the microscopic topographical formation defined above is typically obtained by step a) further comprising a sand-blasting treatment prior to the etching, said sandblasting treatment providing a macroscopic topographical formation .

[0049] Regarding the microscopic topographical formation, the surface parameters are preferably in the range of "SLA®" or "SLActive®" surfaces, given the above-mentioned preferred embodiment in which the etching according to a) is performed according to the SLA® or SLActive® protocol.

[0050] Both the "SLA®" and "SLActive®" treatment are well-known in the respective field and relate to a breakthrough technology in view of the preparation of osteophilic implants. Specifically, "SLA®" involves sandblasting the implant's surface followed by treating it with an etching solution comprising a first mineral acid, whereas "SLActive®" further comprises conditioning the "SLA" surface either in nitrogen or

[0051] A24067WO / 01.10.2025 in an isotonic saline solution, thereby maintaining the high hydrophilicity of the "SLA®" surface which would otherwise be lost during storage due to interaction with the atmosphere .

[0052] According to a preferred embodiment of the present invention, the first etching solution, thus , comprises or essentially consists of a mixture of HC1 and H2SO4 . More particularly, a mixture of HC1 and H2SO4 at a temperature higher than 80 ° C is used for step a ) . Alternatively, any other solution of at least one mineral acid can be used for process step a ) , in particular a solution comprising at least one mineral acid selected from the group consisting of HC1 , H2SO4 , H3PO4 and mixtures thereof .

[0053] For the sand-blasting step , corundum having a particle si ze from 250-500 pm can for example be used as blasting material . According to this embodiment , the sand-blasting step of the SLA® technology is thus applied to the process of the present invention .

[0054] According to a speci fically preferred embodiment , the present invention, hence , involves the same steps as according to the SLA® protocol , but further comprising step c ) after the SLA® etching step .

[0055] Preferably, the process is carried out in a manner that by the sub-microscopic topographical formation formed in step c ) , at least one surface parameter defining the microscopic topographical formation formed in step a ) and being selected from the group consisting of Sa, St and Sst is changed by 50 % at most , preferably by 30 % at most , more preferably by 20 % at most and most preferably is kept essentially unchanged .

[0056] A24 067WO / 01 . 10 . 2025 Thus, the well-established macroscopic and microscopic topographical formation according to the SLA® technology is not altered or only altered to a negligible degree by process step c) . This will be further illustrated by the attached figures showing an almost identical picture at a magnification focussing on the macroscopic and microscopic topographical formation of the surface but showing a completely different picture of the surface at a sub-microscopic level, i.e. at a magnification focussing on the sub-microscopic topographical formation .

[0057] Depending on the specific material of the body and on the process parameters, different sub-microscopic particulate structures can be obtained. Specifically, the sub-microscopic particulate structures extend to a length of more than 50 nm, preferably more than 100 nm, more preferably more than 150 nm.

[0058] As mentioned previously, the sub-microscopic particulate structures are typically crystalline.

[0059] According to a specific embodiment, at least some of the sub- microscopic particulate structures are formed of a plurality of nanosheets (also referred to as "nanolamellae") . The term "nanosheet" or "nanolamella" as used in the context of the present invention denotes a quasi-two-dimensional , planar structure bounded by two parallel major surfaces distanced by a thickness ("t") of the structure. In addition to the thickness, the nanosheet has two in-plane dimensions, i.e. length ("L") and height ("H") , defined along two mutually orthogonal directions within the plane and both perpendicular to the direction of thickness. Typically, L > W, and both L

[0060] A24067WO / 01.10.2025 and W are much larger than t . Speci fically, the nanosheets have a thickness of from 2 to 5 nm .

[0061] At least a portion of the nanosheets may be curved, meaning that their maj or surfaces exhibit an out-of-plane curvature .

[0062] In particular, the nanosheets are arranged in a leaf-like formation, as will be illustrated by way of the figures discussed in the context of the speci fic working examples . In the context of the present invention, a " leaf-like formation" denotes an assembly of discrete nanosheets whose maj or surfaces are , for the most part , mutually separated by gaps , rather than lying broadly face-to- face . The nanosheets may, for example , be arranged in a splayed or imbricated configuration . Partial edge overlap can occur, but the predominant area of each maj or surface remains separated from that of neighboring nanosheets .

[0063] More particularly, the length L and / or the height H of the nanosheets extending in direction perpendicular to the direction of thickness is in a range from 50 to 1000 nm, preferably from 50 to 600 nm, more preferably from 75 to 500 nm and most preferably from 100 to 500 nm .

[0064] The speci fic shape of the sub-microscopic particulate structures is of particular interest in view of protein adsorption, since the leaf-like formation of the nanosheets can further contribute to the retention or "entrapment" of proteins ( in the gap or space between the sheets ) , ultimately allowing for a strong and speci fic adsorption of the proteins of interest .

[0065] A24 067WO / 01 . 10 . 2025 It has surprisingly been found that the sub-microscopic particulate structures are stable in storage media or in air . It has also been found, that on a surface which is hydrophilic ( or superhydrophilic ) the presence of the sub-microscopic particulate structures formed according to the present invention ef fect the hydrophilicity or superhydrophilicity to be maintained even after prolonged storage in air, which would otherwise lead to the surface becoming hydrophobic .

[0066] Depending on the speci fic shape to be achieved, the process parameters are to be chosen respectively .

[0067] According to a speci fically preferred embodiment , the treatment under step c ) is carried out at a temperature of at least 50 ° C, preferably between 50 ° C to 60 ° C, and most preferably at about 55 ° C . This ensures further acceleration of the formation of the sub-microscopic particulate structures and ultimately of the production process of the implant being very short .

[0068] It is preferred that the maturation solution further comprises NaCl in addition to the oxidative agent , preferably at a concentration of about 0 . 9 wt . -% based on the total weight of the maturation solution . As discussed above , the present invention allows the implant , after the treatment for forming the sub-microscopic structures , to remain in the maturation solution for further storing . Hence , the maturation solution takes the further function of the storing solution, and in view of this further function the presence of NaCl at physiological concentration is particularly preferred .

[0069] It is further preferred that the concentration of the oxidative agent in the maturation solution is less than 0 . 08 mol / dm3,

[0070] A24 067WO / 01 . 10 . 2025 preferably less than 0.06 mol / dm3, and most preferably is from 0.02 mol / dm3to 0.05 mol / dm3.

[0071] According to a further preferred embodiment, the treatment in step b) is carried out for a duration in the range of from 0.5 hour to 48 hours, preferably from 1 hour to 36 hours, more preferably from 3 to 24 hours. The duration is thus much longer than what is taught in the above-mentioned article of Milleret et al., according to which the treatment was carried out for 30 seconds only.

[0072] As mentioned, the process of the present includes after the etching according to step a) the further step b) of placing the body into a packaging container before subjecting it to the treatment of step c) . Hence, the body is placed into its final packaging before the sub-microscopic particulate structures defined in c) are fully formed. There is according to the invention hence no necessity for a final packaging step, and it is therefore not required to remove the body from the maturation solution and clean it after step c) , which contributes to a fast and simple workflow in the production process .

[0073] According to a further improved workflow, it is preferred that after step b) the packaging container with the body placed inside is subject to a gamma sterilization treatment. Thus, sterilization is carried out on the body in the situation of its final packaging and any sterilization step that would requiring opening of the packaging and re-packaging of the body can be omitted.

[0074] In a further preferred embodiment, the body is made of a titanium-zirconium alloy, since for this material a

[0075] A24067WO / 01.10.2025 particularly beneficial surface topography can be achieved by the process of the present invention . More preferably, the body is made of a bimetallic titanium- zirconium alloy comprising 13 wt . % to 17 wt . % zirconium, in particular as described in EP-A- 0 988 067 . A particularly preferred titaniumzirconium alloy is available under the tradename Roxolid® ( Institut Straumann AG, Switzerland) , the properties of which being well-known to the person skilled in the art . Alternatively, the body is made of titanium, for which also a surface topography of high relevance can be achieved by the process of the present invention . Depending on the aim to be achieved, the body can also be made of titanium, since it has been found that also for a titanium implant , a topography for improved protein adherence can be achieved by the process of the present invention . Speci fically, the morphology of the sub-microscopic structures obtained can be governed by the choice of the body' s material .

[0076] As pointed out above , the process of the present invention is in particular directed to a dental implant or a dental implant abutment , in order to provide it with a surface that allows for a strong interaction with the surrounding tissue . According to a preferred embodiment , the body is a dental implant or a dental implant abutment and the topography is provided on at least a portion of the surface of the body, which in use is intended to be in contact with bone tissue or so ft tissue , respectively .

[0077] As mentioned above , it is pre ferred that the maturation solution is an aqueous solution of hydrogen peroxide . In this regard, it is further preferred that hydrogen peroxide in the

[0078] A24 067WO / 01 . 10 . 2025 maturation solution is in a concentration of less than 0.1 M, referred to the total weight of the maturation solution.

[0079] Apart from the process described above, the present invention also relates to a body obtainable by the process.

[0080] Specifically, the invention relates to a body in the form of an endosseous implant or a part of an endosseous implant system, the surface of the body being defined by a microscopic topographical formation and sub-microscopic particulate structures formed on the microscopic topographical formation, wherein the microscopic topographical formation is defined by at least one of the following surface parameters: i) Sabeing the arithmetic mean deviation of the surface in three dimensions and being in the range from 0.1 pm to 2.0 pm, preferably being in a range from 0.4 pm to 1.8 pm, more preferably from 0.8 pm to 1.5 pm, and most preferably from 1.0 pm to 1.2 pm; ii) St being the maximum peak to valley height of the profile in three dimensions and being in the range from 4.0 pm to 12.0 pm, preferably being in a range from 6.0 pm to 10.0 pm, and most preferably from 7.0 pm to 9.0 pm; and / or iii) Sat being the skewness of the profile in three dimensions and being in the range from -0.6 to 1.0, preferably from -0.4 to 0.6, more preferably from -0.3 to 0.5.

[0081] The sub-microscopic particulate structures are thereby formed of a plurality of nanosheets, which have a thickness of from 2 to 5 nm.

[0082] A24067WO / 01.10.2025 As noted above , the surface parameters Sa, St and Sst are analogue parameters for three dimensions to the parameters Ra, Rt and Rst, respectively, defined in EN ISO 4287 for two dimensions . Speci fically, the above values relate to the values as e . g . obtainable by the WinSAM software ( SAM ( Surface Analysis Method) for Windows ) known to the skilled person, as mentioned above in the context of the process of the present invention .

[0083] According to a particularly preferred embodiment , the nanosheets are arranged in a leaf-like formation, as also mentioned in the context of the of the process discussed above .

[0084] It is understood that all other features which are described above as preferred features of the process likewise are preferred features of the body of the present invention and vi ce versa .

[0085] In a particularly preferred embodiment of the body, the average length and / or the height of the nanosheets extending in direction perpendicular to the direction of thickness is in a range from 10 to 500 nm, more preferably from 20 to 200 nm and most preferably from 50 to 100 nm . Speci fically, the sub- microscopic particulate structures have a flower-like habitus , the flower head ( or blossom head) of which having on average a dimension in the range of 100 nm to 600 nm, preferably 200 nm to 300 nm .

[0086] The body of the present invention is an endosseous implant or a part of an endosseous implant system, as mentioned above , and preferably is a dental implant or dental implant abutment or a part of a dental implant or dental implant abutment . It is understood that when the body is used as a part of a dental

[0087] A24 067WO / 01 . 10 . 2025 implant or dental implant abutment, at least a portion of the remaining part can be made of a material other than titanium or titanium alloy, respectively.

[0088] If the body is used as a dental implant abutment, the values for Sa, St and Sst are preferably lower than the ones mentioned above, which in particular relate to a bone contacting surface of the body. Specifically, Sais in the case of the body being a dental implant abutment preferably in the range from 0.05 pm to 0.5 pm, and more preferably from 0.05 pm to 0.3 pm. This allows a particularly strong interaction of the dental implant abutment and the surrounding soft tissue to be obtained.

[0089] EXAMPLES

[0090] 1. Materials and Methods

[0091] Material

[0092] Discs were prepared from a bimetallic TiZr alloy rod (Roxolid (RXD) ; 13 - 17 wt . % Zr) . Specifically, discs of 5 mm in diameter and 1 mm in thickness (5 mm x 1 mm) were prepared for the in vitro evaluation tests, and 6.25 mm x 2 mm discs were prepared for the in vivo tests discussed below.

[0093] "SLA" treatment

[0094] First, the samples have been treated according to the protocol for preparing "SLA®" samples. Specifically, the samples have been sand-blasted using corundum with large grits (particle size 250-500 pm) , followed by etching the sand-blasted surface in a boiling mixture of HC1 and H2SO4.

[0095] A24067WO / 01.10.2025 After "SLA" treatment , a first set has been rinsed and after drying been stored in air ; these comparative samples are hereinafter referred to as "SLA" ( or "RXD SLA" ) .

[0096] Samples "SLActive" The samples achieved by the SLA® treatment have been directly immersed, placed into a packaging container and stored in 0 . 9% NaCl solution, according to the SLActive® protocol .

[0097] For comparative reasons , a second portion of samples have been kept without further treatment . The comparative samples are hereinafter referred to as "SLActive" ( or "RXD SLActive" ) .

[0098] Samples "SLActive H2O2"

[0099] A third portion of the samples have after SLA® treatment been directly immersed, placed into a packaging container and treated in an aqueous maturation solution containing predefined amounts of H2O2 and 0 . 9% NaCl (pH 4 . 6 ) at 55 ° C for 1 day . The amount of H2O2 of the respective samples "SLActive H2O2" and the treatment period are indicated in Table 1 .

[0100] Table 1

[0101] A24 067WO / 01 . 10 . 2025

[0102] In the course of these experiments, it was found that with increasing treatment periods, the pH decreased only slightly (down to pH 3.8 after 1 week of storage) .

[0103] The samples were then y (gamma) -sterilized and subject to in vitro evaluation tests described below. In addition, the in vivo osseointegration of the samples was assessed in biomechanical pull-out force studies in rabbits described in further detail below.

[0104] 2. In vitro measurements

[0105] Contact angle measurements

[0106] Contact angle measurements were performed to determine the degree of hydrophilicity or hydrophobicity.

[0107] The contact angles were determined using a sessile drop test with ultrapure water (EasyDrop DSA20E, Kriiss GmbH) . A droplet size of 0.1 pl (microliter) was used and the samples were blown dry in a stream of Ar prior to the contact angle measurements. Contact angles were calculated by fitting a circular segment function to the contour of the droplet on the surface.

[0108] The surfaces of all SLActive H2O2 samples assessed were superhydrophilic exhibiting contact angles of 0°.

[0109] Further experiments have shown that superhydrophilicity was maintained even after storing the SLActive H2O2 sample for 1 month in air.

[0110] A24067WO / 01.10.2025 SEM ( Scanning electron microscopy) and EDX (Energy Dispersive X-Ray Spectroscopy)

[0111] The visual appearance and morphology of the nanostructures were evaluated with scanning electron microscopy ( SEM) .

[0112] SEM measurements were performed on three discs for each type of surface . The measurements were performed on a scanning electron microscope of the type Zeiss Supra 55 . The overview SEM images were acquired with an acceleration voltage of 20 kV using the Everhart-Thornley detector and the high-resolution images with an acceleration voltage of 5 kV using the in-lens detector .

[0113] The SEM images of the SLActive H2O2 samples are given in the attached figures , whereby

[0114] Fig . 1 relates to a SEM image of the surface of sample SLActive H2O2- 1 , the scale corresponding to 200 nanometre being given in the bottom left corner of the image ;

[0115] Fig . 2 relates to a SEM image of the surface of sample SLActive H2O2- 1 shown in Fig . 1 in a higher magni fication, the scale corresponding to 100 nanometre being given in the bottom left corner of the image ;

[0116] Fig . 3 relates to a SEM image of the surface of sample SLActive H2O2-2 in the same magni f ication as in Fig . 2 , the scale corresponding to 100 nanometre being given in the bottom left corner of the image ;

[0117] Fig . 4 relates to a SEM image of the surface of sample

[0118] A24 067WO / 01 . 10 . 2025 SLActive H2O2-3 in the same magni f ication as in Fig . 2 to 3 , the scale corresponding to 100 nanometre being given in the bottom left corner of the image ; and

[0119] Fig . 5 relates to a SEM image of the surface of sample SLActive H2O2-4 in the same magni f ication as in Fig . 2 to 4 , the scale corresponding to 100 nanometre being given in the bottom left corner of the image .

[0120] Roughness parameter determination

[0121] Roughness images were acquired using a confocal microscope (psurf explorer, NanoFocus AG, Oberhausen, Germany) equipped with a 20x lens . Three measurements were performed on each sample disc and three discs were measured for each type of surface . The roughness parameters were calculated using the WinSAM software mentioned above . The whole roughness image with a si ze of 798 pm (micrometre ) x 798 pm (micrometre ) was used for the calculation of the 3D roughness parameters .

[0122] The values of the microscopic topographical formation ( roughness ) were determined using a moving average Gaussian filter with a cut-of f wavelength of 30 pm (x = 31 pm, y = 30 pm, 20 x 19 image points ) . Then, the roughness parameters were calculated by means of a KFL analysis with limits from the amplitude density .

[0123] Speci fically, Sa( the arithmetic mean deviation of the surface in three dimension) , St ( the maximum peak to valley height of the profile in three dimensions ) and Sst ( the skewness ) were determined in analogy to EN ISO 4287 relating to the respective parameters Ra, Rt and Rst in two dimensions . For the parameters

[0124] A24 067WO / 01 . 10 . 2025 in three dimensions , it is further referred to ISO 25178 , in which the symbol Szis used for the maximum peak to valley height of the profile ( instead of the symbol St used in the context of the present invention) .

[0125] Determination of the microroughness values of the SLActive H2O2 samples have revealed that at least the values of Saand St of the SLActive H2O2 samples lie within the same range typically observed for SLA® / SLActive® implants . Speci fically, the Sa, St and Sst values of SLActive H2O2 deviate from the respective values of the SLActive samples by less than 25% .

[0126] As can be seen from Fig . 1 as confirmed by roughness parameter determination, the SLActive H2O2 samples exhibit a very similar macroscopic and microscopic topographical formation as compared to the respective formation obtained by the SLA® treatment , namely by sandblasting and etching the samples in a boiling mixture of HC1 and H2SO4 .

[0127] However, there are distinct di f ferences in the appearance of a sub-microscopic topographical formation . The sub-microscopic ( or nanoscopic ) topographical formation also di f fers between the di f ferent SLActive H2O2 samples . Although all SLActive H2O2 samples show flower-like sub-microscopic structures containing nanosheets arranged in a leaf-like formation, there is a less dense stacking of the nanosheets in samples SLActive H2O2- 1 and SLActive H2O2-2 as compared to SLActive H2O2-3 and SLActive H2O2-4 . Without wanting to be bound by the theory, it is assumed that the " looser" stacking or imbrication of the nanosheets has a beneficial influence in terms of interaction with the surrounding tissue allowing a better adherence of proteins governing osseointegration . In particular, it is

[0128] A24 067WO / 01 . 10 . 2025 assumed that the looser stacking favours the retention or "entrapment" of proteins in the space between the sheets , ultimately allowing for a strong and speci fic adsorption of the proteins of interest .

[0129] 3. In vivo test regarding osseointegration

[0130] To assess the osseointegrative properties of the samples in vi vo, biomechanical pull-out force tests have been carried out in Swedish loop rabbits of both genders and two di f ferent strains ( 18 animals in total ) . Speci fically, the protocol was as follows :

[0131] Pre-surgical phase

[0132] Before surgery, the animals were anaestheti zed and the operation sites were depilated and washed with soft soap and ethanol . Animals were placed on their back on the operation table and covered with a sterile cover .

[0133] Medical oxygen was provided to ensure suf ficient blood oxygen saturation during the whole period of surgery .

[0134] Surgical phase

[0135] An incision was made on the proximal-anterior part of tibiae , penetrating all soft tissue layers . The periosteum was elevated and retained by a sel f-retaining retractor . Four guide holes were made with a 1 . 0 mm diameter twist drill (Medartis , Switzerland) using a drill guide to ensure standardi zed and correct positioning . Using a custom made 7 . 05 mm diameter bur mounted in a slow-speed dental implant drill with copious physiological saline solution irrigation, a platform was made for the disc implants , which have been prepared as explained

[0136] A24 067WO / 01 . 10 . 2025 above in chapter 1. Polytetrafluoroethylene (PTFE) caps were placed to inhibit bone growth towards the vertical parts of the implant as well as bone overgrowth. The implants were stabilized with a pre-shaped 0.25 mm titanium band and retained in the cortical bone with two 1.2 x 3 mm titanium screws (Medartis, Switzerland) . This ensured a stable initial fixation of the implants during the healing period. The soft tissue was repositioned and sutured with resorbable suture

[0137] (Vicryl 4-0, FS2, Ethicon, US) .

[0138] Post-surgical phase

[0139] After surgery the rabbits were brought back into their cages and analgesia (Temgesic, Schering-Plough AB, Stockholm, Sweden, 0.3 mg / ml) was provided for 3 days. The rabbits were kept in the animal facility without transportation during the healing phase. 4 weeks after implantation the rabbits were sacrificed by an overdose of pentobarbital ( Pentobarbitalnatrium, Apoteket AB; Stockholm, Sweden, 60 mg / ml) . The legs were cut at ~5 cm below the knee joint and were wrapped in wet tissues (saline 0.9 % solution) to avoid drying .

[0140] Biomechanical pull-out force

[0141] Prior to pull-out measurements an incision was made through the soft tissue on the tibial bone. The titanium plate covering the implants was exposed and removed. A hole was made in the centre of the PTFE cap with a hollow needle, and pressurized air was applied to remove the caps and expose the reverse part of the implant. The use of this technique introduced only marginal loads to the implants. The tibial bone was fixated in a specially designed device during the pull-out test

[0142] A24067WO / 01.10.2025 procedure. The set-up was then adjusted in line and perpendicular with the load-cell using a level tube, such that the applied force is acting at the centre of the disc, perpendicular to its surface. The test was performed with a Zwick Roell Z 2.5 testing machine (Ulm, Germany) fitted with a calibrated load-cell of 250 N. Cross-head speed range was set to 1.0 mm / min. The load was applied until loosening of the implant and recorded on a load versus time plot.

[0143] Results

[0144] The results of the tests are represented in

[0145] Fig. 6 showing the maximum pull-out forces determined for sample SLActive H2O2-1 ("SLActive 0.5% peroxide") and comparative sample SLActive H2O2-3 ("SLActive 5% peroxide") in further comparison to samples "SLA", "SLActive" and "SLActive HF" as well as sample "Machined 5% peroxide".

[0146] Specifically, Fig. 6 shows for sample SLActive H2O2-1 comparable osseointegration as for comparative samples SLA and SLActive, on which nanostructures have been grown over a long storage period of more than two weeks. In addition, Fig. 6 shows higher maximum pull-out force values (indicative of improved osseointegration) as compared to the sample SLActive H2O2-3 subjected to a short-time treatment using an aqueous solution falling outside the scope of the claim. These values were also much higher than the values determined for comparative sample "Machined 5% peroxide" (i.e. not subject to SLA treatment) which were close to 0 N.

[0147] A24067WO / 01.10.2025

Claims

28Claims1 . Process for the preparation of an osseointegrative topography on a surface of a body made of titanium or a titanium alloy, the body being an endosseous implant or a part of an endosseous implant system, the process comprising the subsequent steps of a ) etching the surface of the body with an etching solution comprising a mineral acid, whereby a microscopic topographical formation is provided, b ) placing the body obtained in step a ) into a packaging container, and c ) treating the body placed inside the packaging container with an aqueous saline maturation solution comprising an oxidative agent , whereby sub-microscopic particulate structures are formed on the microscopic topographical formation, said sub-microscopic particulate structures extending in at least two dimensions to 1 pm at most , characteri zed in that the maturation solution used in step c ) is a solution of an oxidative agent selected from the group consisting of hydrogen peroxide , sodium nitrate and potassium nitrate as well as mixtures thereof , the concentration of the oxidative agent in the maturation solution being in a range of higher than 0 . 001 mol / dm3and less than 0 . 1 mol / dm3, and that the treatment of step c ) is carried out at a temperature of above 40 ° C .A24 067WO / 01 . 10 . 20252. Process according to claim 1, wherein the microscopic topographical formation is defined by at least one of the following surface parameters Sa, St and SSk being analogue parameters for three dimensions to the parameters Ra, Rt and RSk, respectively, defined in EN ISO 4287 for two dimensions : i) Sabeing the arithmetic mean deviation of the surface in three dimensions and being in the range from 0.1 gm to 2.0 gm, preferably being in a range from 0.4 gm to 1.8 gm, more preferably from 0.8 pm to 1.5 pm, and most preferably from 1.0 gm to 1.2 gm; ii) St being the maximum peak to valley height of the profile in three dimensions and being in the range from 4.0 gm to 12.0 gm, preferably being in a range from 6.0 gm to 10.0 gm, and most preferably from 7.0 gm to 9.0 gm; and / or iii) Sat being the skewness of the profile in three dimensions and being in the range from -0.6 to 1.0, preferably from -0.4 to 0.6, more preferably from -0.3 to 0.5.

3. Process according to claim 2, wherein by the sub- microscopic particulate structures formed in step c) , at least one surface parameter defining the microscopic topographical formation provided in step a) and being selected from the group consisting of Sa, St and Sst is changed by 50 % at most, preferably by 30 % at most, more preferably by 20 % at most and most preferably is kept essentially unchanged.A24067WO / 01.10.20254. Process according to any of the preceding claims, wherein the treatment under step c) is carried out at a temperature of at least 50°C, preferably between 50°C to 60°C, and most preferably at about 55°C.

5. Process according to any of the preceding claims, wherein the maturation solution further comprises NaCl in addition to the oxidative agent, preferably at a concentration of about 0.9 wt.-% based on the total weight of the maturation solution.

6. Process according to any of the preceding claims, wherein the concentration of the oxidative agent in the maturation solution is less than 0.08 mol / dm3, preferably less than 0.06 mol / dm3, and most preferably is from 0.02 mol / dm3to 0.05 mo 1 / dm3.

7. Process according to any of the preceding claims, wherein the treatment in step b) is carried out for a duration in the range of from 0.5 hour to 48 hours, preferably from 1 hour to 36 hours, more preferably from 3 to 24 hours.

8. Process according to any of the preceding claims, wherein after step b) the packaging container with the body placed inside it is subject to a gamma sterilization treatment.

9. Process according to any of the preceding claims, wherein the topography is provided on at least a surface portion of the body, which in use is intended to be in contact with hard tissue or soft tissue, respectively.

10. Process according to any of the preceding claims, wherein the maturation solution is an aqueous solution of hydrogenA24067WO / 01.10.2025peroxide in a concentration of less than 0.1 M, referred to the total weight of the maturation solution.

11. Body obtainable by the process according to any of the preceding claims, the body being an endosseous implant or a part of an endosseous implant system and the surface of the body being defined by a microscopic topographical formation and sub-microscopic particulate structures formed on the microscopic topographical formation, wherein the microscopic topographical formation is defined by at least one of the following surface parameters Sa, St and Sst being analogue parameters for three dimensions to the parameters Ra, Rt and Rst, respectively, defined in EN ISO 4287 for two dimensions: i) Sabeing the arithmetic mean deviation of the surface in three dimensions and being in the range from 0.1 pm to 2.0 pm, preferably being in a range from 0.4 pm to 1.8 pm, more preferably from 0.8 pm to 1.5 pm, and most preferably from 1.0 pm to 1.2 pm; ii) St being the maximum peak to valley height of the profile in three dimensions and being in the range from 4.0 pm to 12.0 pm, preferably being in a range from 6.0 pm to 10.0 pm, and most preferably from 7.0 pm to 9.0 pm; and / or iii) Sst being the skewness of the profile in three dimensions and being in the range from -0.6 to 1.0, preferably from -0.4 to 0.6, more preferably from -0.3 to 0.5,A24067WO / 01.10.202532 and wherein the sub-microscopic particulate structures are formed of a plurality of nanosheets , which have a thickness of from 2 to 5 nm .12 . Body according to claim 11 , wherein the nanosheets are arranged in a leaf-like formation .13 . Body according to claim 11 to 12 , wherein the average length and / or the height of the nanosheets extending in direction perpendicular to the direction of thickness is in a range from 10 to 500 nm, more preferably from 20 to 200 nm and most preferably from 50 to 100 nm .A24 067WO / 01 . 10 . 2025

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