Dental implant

Abstract

The invention relates to a dental implant comprising an implant surface having at least partially a contact angle of less than 20°, which is at least partially covered by a protective layer comprising a keratin hydrolysate.

Description

[0001] This invention relates to dental implants that are at least partially covered by a protective layer.

[0002] Dental implants are used to replace single teeth or to anchor more complex structures, often replacing several or even all teeth. An implant has two basic components: an anchoring component and an abutment component. The anchoring component is embedded in the bone, where it osseointegrates with the bone tissue to provide a strong anchor for the prosthesis. The abutment extends into the oral cavity and provides support for the prosthesis. The desired prosthetic element (such as a bridge or crown) is secured to the abutment to accommodate at least a portion of the abutment within the prosthesis and to provide core support for it. The prosthetic element can be glued, cemented, screwed, or directly veneered to the abutment.

[0003] Implants, such as dental implants, are well known in the field. They are typically composed of biocompatible materials that also possess advantageous mechanical properties.

[0004] In addition, good osseointegration is required for dental implants. The term "osseointegration" refers to the direct structural and functional connection between the living bone and the surface of the load-bearing implant. Good osseointegration means that after the implant achieves initial stability by screwing it into the bone, it safely ossifies within a short healing time, thus achieving a permanent bond between the implant and the bone.

[0005] In the early stages of modern implantology, a minimum rough surface was the gold standard. Later, in several experimental studies using various animal models, an increase in moderately rough surfaces led to faster and stronger osseointegration.

[0006] A breakthrough technique in the development of highly osseointegrated dental implants is the so-called “SLA” method disclosed in EP 0388576, which involves sandblasting the surface of the implant and then acid etching it to achieve the optimal morphology for bone cell attachment.

[0007] Based on "SLA" technology, a so-called "SLActive" surface was developed and disclosed in WO 00 / 44305, which further includes conditioning the "SLA" surface in nitrogen or in an isotonic salt solution, thereby maintaining the high hydrophilicity of the "SLA" surface, which would otherwise be lost due to reaction with the atmosphere. The packaging process is time-consuming and expensive, which is a drawback of this procedure.

[0008] US 2014 / 172028 discloses a surface treatment method for intraosseous implantable medical devices, which involves covering the surface of the medical implant with sugar or sugar alcohol.

[0009] WO 2018 / 189185 discloses a dental implant made of ceramic material. The implant surface has at least a portion having a contact angle of less than 20°, and the implant surface is at least partially covered by a protective layer. The protective layer comprises a water-soluble dextran with a molecular weight greater than 15,000 Da.

[0010] WO 2008 / 098976 discloses a method for producing an implant with a hydrophilic surface by covering the surface of the implant with a salt-containing layer.

[0011] US 2009 / 0132048 discloses a dental implant having at least a portion of a protective layer composed of salts that dissolves upon contact with body fluids and / or bone. However, salt-containing protective layers, particularly those composed of NaCl, exhibit reduced long-term stability.

[0012] WO 03 / 030957 discloses an implant having a roughened hydroxylated and hydrophilic surface, treated with high-energy ultraviolet radiation in the hydroxylated state. One drawback of this solution is the additional treatment steps that should be performed specifically by a surgeon.

[0013] Campbell et al. disclosed the effect of keratin hydrogels on bone integration.

[0014] The purpose of this invention is to provide a protective layer for dental implants that prevents the surface from becoming hydrophobic. Furthermore, the protective layer needs to be biocompatible, and the product should not suffer from hydrothermal aging while being hydrophilic.

[0015] This problem is solved by the dental implant of the present invention.

[0016] A dental implant has been discovered that provides excellent osseointegration, comprising an implant surface having at least a portion of a contact angle of less than 20°, the implant surface being at least partially covered by a protective layer comprising keratin hydrolysates. The protective layer preferably has a water content of less than 10% by weight. Interestingly, the protective layer no longer needs to be removed by a dentist before implantation. Furthermore, the protective layer ensures hydrophilicity until implant-bone contact is established. Due to its composition, the protective layer according to the invention is biocompatible and has good accessibility.

[0017] The protective layer according to the invention prevents contaminant deposition on the implant surface, which at least partially has a contact angle of less than 20°. Furthermore, the contact angle on the protective layer surface is less than 20°, meaning that even the protective layer itself has excellent wettability, which allows for accelerated osseointegration even without removing the protective layer. In particular, it can be shown that the protective layer according to the invention can withstand harsh conditions such as high humidity, low temperature, or low pressure. The protective layer of the dental implant according to the invention maintains surface hydrophilicity during storage in air.

[0018] The standard parameter for determining surface hydrophilicity is the measurement of the water contact angle (DIN 55660-2). The contact angle quantifies the water wettability of the implant, and thus the degree of contact with the hydrophilic environment. As used in the context of this invention, the term "contact angle" refers to the angle of contact between water and a surface, i.e., the angle formed at the interface where water meets the surface. Therefore, the term "water" used in the context of contact angle measurement refers to pure water, especially ultrapure water. Specifically, the contact angle measurement is performed by the seated drop method (e.g., using a device of the EasyDrop DSA20E type, Kruss GmbH), using a droplet size of 0.1 μL for a 5 mm diameter hydrophilic disc and 0.3 μL for a 5 mm diameter hydrophobic disc, meaning that the keratin-coated disc is measured using a 0.1 μL microdrop. The contact angle is calculated by fitting a circular arc function to the profile of the microdroplet placed on the surface. As used in the context of this invention, the term "hydrophilic" or "hydrophilic" means that the water contact angle of the hydrophilic surface area directly on the dental implant is less than 20°, more preferably less than 10°.

[0019] Such hydrophilic surfaces with a contact angle of less than 20° can be obtained, for example, through so-called SLA technology or through other etching processes.

[0020] The term "keratin hydrolysate" refers to the hydrolysate obtained from keratin, in which the peptide chain is broken down into smaller peptides with lower molecular weights, i.e., less than 20,000 g / mol. The molecular weight of the keratin hydrolysate can be determined, for example, by SDS-PAGE or by measuring absorbance at 280 nm. Keratin hydrolysates can be prepared, for example, by acid or alkaline hydrolysis or by enzymatic digestion. Commonly used keratin sources can be derived from several sources, such as human hair fibers, wool, animal hair, feathers, and horn.

[0021] Since keratin hydrolysates exist as colloids in solution, they can interact with blood and thereby promote protein absorption and the formation of a blood component layer on the implant surface.

[0022] Preferably, the keratin hydrolysate has an average molecular weight of less than 20,000 Da, more preferably less than 10,000 Da, and most preferably less than 5,000 Da. It must be assumed that such keratin hydrolysate produces a very dense, well-structured protective layer.

[0023] The molecular weight of keratin hydrolyzates can be determined, for example, by SDS-PAGE on tricine polyacrylamide gel in a minicell Novex Model-3540 (USA) using a constant voltage of 125 V and a current intensity of 80 mA at the beginning and 40 mA at the end (Krejci et al., preparation and characterization of keratin hydrolyzates, Mathematical Methods and Techniques in Engineering and Environmental Science, ISBN: 978-1-61804-046-6).

[0024] Preferably, the protective layer has a thickness of 30 to 200 nm, most preferably 30 to 90 nm. Interestingly, such a thin layer can protect the hydrophilicity of the dental implant while maintaining the roughness of the implant surface and thus providing better adhesion. Therefore, dental implants covered with the protective layer according to the invention exhibit substantially the same surface roughness as dental implants without the protective layer.

[0025] In fact, the density of the protective layer according to the invention is significant. The density of the protective layer composed solely of keratin hydrolysates and the protective layer containing keratin hydrolysates and salts are both about 5% higher than the corresponding protective layer containing glucose and salts.

[0026] In one embodiment of the invention, the protective layer further comprises a salt, preferably a divalent salt, and most preferably MgCl2.

[0027] In a further embodiment of the invention, the protective layer is substantially free of any salt. Such a layer exhibits excellent uniformity and is virtually crack-free. Furthermore, the microroughness of the protective layer of the present invention is comparable to that of an uncoated dental implant. In fact, it is even difficult to distinguish between samples with and without the protective layer using scanning electron microscopy (SEM).

[0028] Furthermore, it is shown that the protective layer according to the invention avoids hydrothermal aging and maintains the hydrophilicity of the implant surface over time, preferably for at least one year, especially for Y-TZP ceramic materials.

[0029] Preferably, the dental implant containing the protective layer according to the invention is sterilized with ethylene oxide gas. This technique can be applied to already packaged dental implants. Ethylene oxide gas permeates the packaging and reaches the dental product to be sterilized. It can be shown that sterilization with ethylene oxide gas does not negatively affect the stability of the protective layer. The hydrophilicity of the surface remains stable, which is particularly relevant when the dental implant is stored for relatively long periods. In particular, when subjected to climatic stress exceeding 8 weeks, the protective layer according to the invention exhibits significantly better hydrophilicity compared to protective layers containing, for example, agarose. Even after ethylene oxide (EO) sterilization, the implant surface coated with the protective layer according to the invention remains highly attractive to blood. Unprotected implants do not exhibit the same affinity for blood, consistent with their hydrophobic properties.

[0030] Preferably, the protective layer does not contain hydroxyapatite, because the density of a protective layer without hydroxyapatite is higher than that of a protective layer containing a combination of keratin hydrolysates and hydroxyapatite.

[0031] Preferably, the dental implant is made of ceramic, and more preferably of yttrium-stabilized zirconia ceramic. One of the main advantages of zirconia implants is their natural white color, making them difficult to distinguish from natural teeth. Furthermore, zirconia implants induce higher fibrinogen uptake and a lower risk of bone loss. The protective coating on ceramic dental implants exhibits similar characteristics to uncoated implants, except for a slight reduction in image sharpness, i.e., smoother edges in the morphology.

[0032] Alternatively, the dental implant may be made of metal, preferably titanium or a titanium alloy. A preferred titanium alloy is a binary titanium-zirconium alloy, and most preferably a binary titanium-zirconium alloy containing 13 to 17% by weight, more preferably 13 to 15% by weight of zirconium. This material has been shown to exhibit excellent properties in terms of mechanical stability and biofunctionality; particularly preferred binary titanium-zirconium alloys containing zirconium within the aforementioned range may be available under the trade name... Obtained from (Institut Straumann AG, Switzerland). It has been shown that the protective layer according to the invention can also maintain the hydrophilicity of such implants until contact between the implant and bone is established.

[0033] Dental implants according to the invention can be constructed from one or more components, in which case they consist at least of an anchoring component (usually referred to separately as the implant) and an abutment (sometimes referred to as a spacer or post element). The anchoring component is typically either fully embedded in the bone, that is, up to the height of the alveolar ridge (so-called bone-level implant), or protrudes a few millimeters from the alveolar ridge into the soft tissue (so-called soft tissue-level implant). The abutment is attached directly or indirectly to the anchoring component after the anchoring component has been fused (osseointegrated) into the bone or immediately after the anchoring component has been embedded. It can also be attached to the anchoring component before embedding.

[0034] Preferably, this anchoring component of a multi-part dental implant is typically cylindrical or conical, having a apex together with the body portion and a coronal end together with the neck portion to receive the abutment in the case of a multi-part implant, as well as a transition portion axially arranged between the body portion and the neck portion. On the abutment, a crown, bridge, or other superstructure can be fixed, for example by screwing, cementing, or gluing. The body portion is intended to be directly against bone in the implanted state, and the neck portion is intended to be directly against soft tissue, while the transition portion can be directly against either bone or soft tissue, depending on the patient. Preferably, the total length of the anchoring component is 4 to 19 mm axially. The body portion with the apex is preferably 50% to 90% of the total axial length of the implant. The coronal end of the neck portion, which is primarily intended to contact soft tissue, preferably covers 10% to 40% of the total axial length of the implant. The transition portion preferably covers 0% to 40% of the total axial length of the implant. The neck preferably has a length of 1 to 4 mm, most preferably 1.8 to 2.8 mm, the transition portion preferably has a length of 0 to 2 mm, most preferably 1 to 2 mm, and the main body preferably has a length of 4 to 18 mm.

[0035] The main body typically includes threaded portions, which can be self-tapping or non-self-tapping.

[0036] Similar to multi-component implant systems, the anchoring component of such monoparticle implants is typically cylindrical or conical, with a apex that aligns with the body and a coronal end that aligns with the neck, which enters the abutment. The anchoring component usually has a threaded portion, which can be self-tapping or non-self-tapping. A transition portion is axially positioned between the body and the neck. On the abutment portion, a crown, bridge, or another superstructure can be secured, for example, by screwing, cementing, or gluing. The body is designed to abut directly against bone in the implanted state, and the neck is designed to abut directly against soft tissue, while the transition portion can abut directly against bone or soft tissue, depending on the patient.

[0037] According to the invention, the protective layer at least partially, preferably completely, covers the hydrophilic surface of the dental implant, and is preferably a continuous, crack-free layer. In particular, if not only the main body, but also the transition portion or the transition portion and neck are covered by the protective layer, then the protective layer is preferably a continuous layer.

[0038] To achieve excellent osseointegration, the body portion is typically provided with a surface roughness. In the context of this invention, the term "surface roughness" represents "arithmetic mean height" (Sa). Specifically, the surface roughness Sa (arithmetic mean deviation of the surface in three dimensions) is determined similarly to ENISO 4287, which relates to the corresponding parameter Ra in two dimensions. For the parameter in three dimensions, further reference is made to ISO 25178 (Sa is defined as Sq). Preferably, the surface roughness (Sa) is 2 to 10 μm, more preferably 2 to 5 μm. Surprisingly, the surface roughness can be maintained by the protective layer according to the invention because this layer is extremely thin.

[0039] Preferably, the protective layer has a water content of less than 1% by weight. The absence of water is required to achieve a stable protective layer.

[0040] According to a further embodiment, the main body has a machined but hydrophilic surface. Therefore, the dental implant is acid-etched, but no roughening steps such as sandblasting are used.

[0041] Preferably, the dental implant coated with a protective layer is prepared by a method comprising at least the following steps:

[0042] a) Provide a dental implant surface with a contact angle of less than 20°;

[0043] b) Cover at least partially the surface of the dental implant with a contact angle of less than 20° with a solution or suspension containing keratin hydrolysate;

[0044] c) Dry the dental implant to obtain a protective layer.

[0045] To provide a dental implant surface with a contact angle of less than 20°, it is preferable to etch the dental implant with an inorganic acid or a blend of inorganic acids. More preferably, one or more inorganic acids are selected from hydrofluoric acid, hydrochloric acid, sulfuric acid, or mixtures thereof. Prior to this, the implant may be at least partially mechanically roughened and / or roughened by using plasma technology and / or by laser structuring or by other methods known to a technician.

[0046] The preferred surface morphology of the implant according to the invention can be obtained, for example, by applying the methods described in EP 1 982 670 or EP 1 982 671 before coating the roughened and etched surface. The disclosures of EP 1 982 670 and EP 1 982 671 are incorporated herein by reference.

[0047] Preferably, the surface of the dental implant is at least partially covered by immersing it in an aqueous solution or suspension containing keratin hydrolysates. However, other methods of applying an aqueous solution to the surface to be protected are also feasible. The immersion process ensures a constant thickness of the protective coating.

[0048] Preferably, the drying in step c), i.e., the removal of water, is performed by microwave treatment or by drying with clean air (without special drying, but by storing in a clean environment at room temperature), in a convection oven, a vacuum oven, or in an airflow, wherein the airflow preferably has a temperature of 20°C to 80°C, most preferably 30°C to 40°C. Preferably, the dental implant according to the invention is dried in a convection oven at 20 to 80°C, preferably 70°C, for 10 to 120 minutes, preferably 15 to 90 minutes, most preferably 20 to 60 minutes, to ensure that the protective layer is completely dry. The above drying method does not cause the coating material to splash onto the sample and avoids hydrothermal aging.

[0049] Preferably, the hydrolyzed keratin is dissolved in an aqueous solution or aqueous suspension at a concentration of 0.1 to 10% by weight / volume (w / v), more preferably 1 to 5% by weight / volume (w / v).

[0050] Attached Figure

[0051] The invention is further illustrated by the following figures and embodiments:

[0052] Figure 1 The first embodiment of the present invention is involved;

[0053] Figure 2 The second embodiment of the present invention is involved;

[0054] Figure 3 The third embodiment of the present invention is involved;

[0055] Figure 4 The fourth embodiment of the present invention is involved;

[0056] Figure 5 The fifth embodiment of the present invention;

[0057] Figures 6a to 6c This relates to the static contact angle of different protective layers with different synthesis parameters for the coating process. Figure 6a This shows the SCA (static contact angle) after changing the coating time. Figure 6b Showing the SCA after changing the coating volume. Figure 6c The SCA is shown to have a machined surface rather than an SLA surface.

[0058] Figure 7aThis shows the surface micro-roughness measured on the disk as a function of keratin concentration. Figure 7b Displaying the microroughness measurement of a dental implant coated with ZLA.

[0059] Figure 8a The static contact angles of the keratin protective layer are shown at low and high concentrations. Figure 8b The static contact angles are shown for low-concentration protective layers with and without water washing pretreatment.

[0060] Figure 9 Displays the static contact angle affected by EO sterilization or climatic stress cycles.

[0061] Figure 10 The static contact angle of the protective layer is shown at low concentrations and different storage times.

[0062] Figure 11a and 11b Displays a 3D surface representation of the ZLA dental implant roughness measurement from the vertex region.

[0063] Figure 1 This illustrates the anchoring component 1 of a two-part implant system. Such an anchoring component 1 is made of ceramic material, preferably yttrium-stabilized zirconia. The anchoring component 1 is cylindrical, having a top end 25 together with the body portion 20 and a coronal end 35 together with the neck portion 30 intended to receive the abutment, and a transition portion 40 axially A-oriented between the body portion 20 and the neck portion 30. The neck portion 30 includes an unthreaded portion 31 that tapers outwardly in the coronal direction and terminates at a shoulder portion 32 having an inwardly tapering surface. The body portion 20 is intended to directly abut against bone tissue in the implanted state, while the neck portion 30 is intended to directly abut against soft tissue in the implanted state. The transition portion can directly abut against both soft and bone tissue, depending on the depth of implant insertion or tissue response. The surface of the body portion 20 has a contact angle of less than 20°, and is preferably completely covered by the protective layer 10.

[0064] Figure 2 This illustrates another embodiment of the invention. (Compared to...) Figure 1 Compared to the previous implementation, not only the main body 20 of the anchoring component, but also the transition portion 40 is at least partially, preferably completely, coated with the protective layer 10. Preferably, in the apical direction, at least 25%, most preferably at least 50%, of the circumferential surface area of ​​the transition portion is covered by the protective layer 10. Preferably, at least a portion, preferably the entire surface of the transition portion, also has a contact angle of less than 20° before it is covered by the protective coating 10. However, it is also possible that only the surface of the main body of the dental implant has a contact angle of less than 20°, but the protective layer covers both the main body and the transition portion. This ensures that the hydrophilic surfaces at the edges are also fully protected by the protective layer.

[0065] Figure 3 This illustrates another embodiment of the invention. (Compared to...) Figure 1 Compared to the previous implementation, not only the main body 20, but also the transition portion 40 and the neck 30 (excluding the shoulder 32) are completely coated with the protective layer 10. At least a portion of the transition portion, preferably the entire surface, and at least a portion of the neck also have a contact angle of less than 20° before being covered by the protective layer 10. It can be shown that the hydrophilic surface not only ensures good osseointegration but also positively influences adhesion to soft tissue. However, it is also possible for only the surface of the main body of the dental implant and optionally a portion of the transition portion to have a contact angle of less than 20°, but for the protective layer to cover both the main body and the transition portion.

[0066] Figure 4 This illustrates the anchoring component 101 of a so-called bone-level implant. Such bone-level implants are typically fully embedded in the bone, that is, up to the height of the alveolar ridge. The anchoring component 101 is made of a ceramic material, preferably yttrium-stabilized zirconia. The anchoring component 101 is cylindrical, having a apex 125 together with the body portion 120 and a coronal end 135 designed to receive the abutment. Figure 1 Compared to the dental implants shown, the anchoring component of the bone-level implant has no neck. The body portion 120 is designed to rest directly against the bone tissue in the implanted state. The surface of the body portion 120 has a contact angle of less than 20° and is completely covered by the protective layer 110.

[0067] Figure 5 This illustrates a single-type dental implant 200. The single-type dental implant 200 is made of ceramic material, preferably yttrium-stabilized zirconia. It includes an anchoring member 205 having a threaded section 210. The anchoring member 205 transitions at its upper end 215 via a slightly outwardly widened tapered neck 220 into a mounting member 225 integral with it and extending within the extension of the longitudinal axis 230 of the threaded section. The anchoring member 205 is cylindrical, having a top end 235 together with the body portion 240 and a crown end 245 together with the neck 220, and a transition portion 250 axially A-arranged between the body portion 240 and the neck 220.

[0068] Mounting component 220 has a truncated conical or conical shape and may have at least one flattening 230 on one side thereof.

[0069] On the side opposite to the at least one flat portion 260, a groove 265 may be present in the outer surface, extending upward from the coronal anterior surface of the mounting member 225 and terminating in a tapered section, thus forming a transition to the tapered section of the anchoring member 205. The flat portion 260, in conjunction with the groove 265 on the opposite side, serves to provide a forward tightening tool with a mating insert seat. Alternatively, the mounting member may provide other means for receiving the tightening tool. The body portion 240 is intended to directly abut against bone tissue in the implanted state, and the neck portion 220 is intended to directly abut against soft tissue, while the transition portion 250 may directly abut against bone tissue or soft tissue, depending on the patient. The surface of the body portion 240 has a contact angle of less than 20°, and is at least partially, preferably completely, covered by the protective layer 270. Optionally, not only the body portion 240 but also the transition portion 250 of the anchoring member is hydrophilic. Preferably, the transition portion 250 has a contact angle of less than 45°, more preferably less than 20°, and is covered by the protective layer 270. Preferably, at least 25%, most preferably at least 50%, of the circumferential surface area of ​​the tip of the transition portion is covered by the protective layer 250. This allows for greater flexibility during implantation and ensures that the entire surface intended for contact with bone tissue is hydrophilic. Example

[0070] Material

[0071] In the context of this invention, the term ZLA represents yttrium-stabilized zirconia, specifically 3Y-TZP according to DIN ISO 12677, having a surface that has been sandblasted (corundum 0.1-0.4 mm, 6 bar) and acid-etched (e.g., HF). The keratin hydrolysate used is a product with a molecular weight of 2000 g / mol. Keratin LM, BASF (CAS-Nr. 69430-36-0). Ker:MgCl2 represents a 9:1 ratio. The Keratin LM:MgCl2 ratio results in a keratin solution with a concentration of 1 mg / ml and a MgCl2 solution with a concentration of 0.05 M.

[0072] In the context of this invention, "low concentration" means about 1 mg / mL (i.e., for example 1 mg / mL). KeratinLM is obtained by adding 870 μl of water to every 100 ml of Nutrilan Keratin at a concentration of 115 mg / ml. The expression "high concentration" means approximately 30 mg / mL.

[0073] O2 plasma cleaning (hydrophilic treatment, HPL treatment)

[0074] The samples used for the coating experiment were cleaned and stored as follows:

[0075] Open the gas cylinder and connect the O2 plasma cleaner and valve to the plasma. Press the pump button and wait until the pressure drops below 8*10. -2 Connect the gas flow to millibars. Increase the gas flow rate (up to 4-5 x 10⁻⁶). -1 (mbar) and wait 5 minutes. Reduce the gas flow rate to 1*10 -1 Press the Generation button and set the parameters to 4 minutes (or two cycles of 2 minutes) and 35W. Adjust the flow rate to 0 and shut off the gas. Stop the pump and open the chamber (ventilation button). Remove the sample holder from the inside. Place the sample to be cleaned. Start the cleaning procedure. Measure the contact angle of 3 samples to ensure the process is successful (the contact angle must be 0 degrees).

[0076] Coating process - disc

[0077] The sample was immersed in the impregnation solution in a coating beaker for 3 minutes under acoustic treatment, then placed on a Teflon mesh and oscillated at 150 rpm for 3 minutes to obtain a more uniform coating and then dried. Drying was carried out with circulating air at 55°C for 15 minutes to dry the coating on the sample.

[0078] Storage: If EO sterilization is not performed, store the sample in a 24-well plate under laminar flow.

[0079] Coating procedure - implant

[0080] The procedure is the same as for the trays, with the following exceptions: no implant support is used. They are individually immersed in the coating solution and removed with ceramic forceps. Furthermore, the implants are not placed in a Teflon mesh for drying, but rather directly in their primary implant packaging.

[0081] static contact angle

[0082] The experimental procedure was performed according to DIN 55660-2:2011-12. Typically, the static contact angle was determined using ultrapure water in a seat drop test (EasyDrop DSA20E, Kruss GmbH). Water droplets of 0.1 μL size for a 5 mm diameter hydrophilic disc and 0.3 μL size for a 5 mm diameter hydrophobic disc were dispensed using an automated unit. The contact angle was calculated by fitting an arc function to the profile of the droplets placed on the surface. The contact angle was determined under two different conditions: (a) without washing off the protective layer, and (b) after rinsing the sample with UPw for 15 seconds and then drying it in an Ar stream to remove the coating.

[0083] like Figures 6a to 6c As shown, the protective layer according to the invention can be made in a reproducible manner. The coating duration is shown to be 30 seconds vs. 180 seconds. Figure 6aThe volume of the coating solution (2 ml vs 12.5 ml) and the volume of the coating solution. Figure 6b There was no significant effect on the static contact angle (SCA). Furthermore, it was shown that other surfaces (such as machined rather than SLA) exhibited improved wettability and therefore higher hydrophilicity compared to uncoated machined surfaces. Figure 6c ).

[0084] In addition, Figure 8a The study showed that increasing the concentration of keratin hydrolysates (KerL 1 mg / mL vs. KerH 30 mg / mL) did not alter hydrophilicity (no EO sterilization, n=1 measurement, t=1 week, protective layer not washed). For example... Figure 8b As shown, other protective layers (such as glucose) at low concentrations (1 mg / mL) cannot provide the required contact angle below 25°.

[0085] Among the low-concentration protective layers studied, only the disc coated with a low concentration of keratin hydrolysate met the standard of a contact angle below 25° without requiring additional washing steps by clinicians to ensure sufficient hydrophilicity of the surface during implantation. Figure 9 Static contact angles of low-concentration (1 mg / mL) protective layers and low-concentration and high-concentration (1 mg / mL vs. 10 mg / mL) keratin layers; EO sterilization; n = 2 samples; t = 4 weeks). Lower contact angles were also observed when using higher concentrations of sugar-containing protective layers, such as 30 mg / mL fructose, although the longer storage time involved suggests possible degradation of the sugar-containing layer. Figure 10 Static contact angle of the protective layer during 4-week and 52-week storage periods; EO sterilization; n = 3 samples; PL not removed).

[0086] Dynamic contact angle

[0087] According to the Wilhelmy plate method using a tensiometer (Lauda TE 3, Lauda Dr.R.Wobser GmbH&Co.KG), the surface tension can be calculated from the necessary force required for a particular solid when it is immersed in and subsequently removed from the liquid.

[0088] Dynamic contact angles measured on coated ZLA implants showed that the coating with keratin hydrolysates resulted in a superhydrophilic implant surface, significantly superior to their counterparts.

[0089] Thickness estimated using a microbalance

[0090] The effective micro-roughness values ​​were calculated using 3D roughness values ​​measured with a low-pass Gaussian filter at a cutoff frequency of 30 μm, according to a procedure defined by Straumann Research. Values ​​from the uncoated sample were used in all calculations, as this is the surface suitable for coating.

[0091]

[0092] Sample preparation before weight measurement

[0093] The sample must be dried before weight measurement (in an oven at 55°C for 15 minutes; then at 110°C for 40 minutes).

[0094] The weight difference of the disc before and after coating yielded the following thickness estimates:

[0095] protective layer Estimate thickness (nm) <![CDATA[Density (mg / mm 3 )]]> FruMgH 1349.54 1.03 KerMgL 66.40 1.06 GluMgH 615.54 1.01 DexMgH 618.50 1.1

[0096] Surface micro-roughness

[0097] Because the samples exhibit specific micro-surface roughness after sandblasting and acid etching, this specific roughness parameter will vary depending on the coating. These parameters are defined by ISO 25178:

[0098] Ssk(AU): Skewness represents the symmetry of the surface height relative to the mean plane. If this parameter is greater than 0, the peaks predominate over the valleys, while if this parameter is less than 0, the valleys predominate.

[0099] Sa(μm) and Sz(μm): Arithmetic mean height and maximum height represent measures of surface texture, containing information about peaks and valleys, as well as information about the spacing between these surface features.

[0100] Sdr(μm): Developed interfacial area ratio represents the percentage of additional surface area that must be added relative to a completely flat surface without texture.

[0101] Before analyzing the samples, they should be briefly rinsed under argon to remove dust from the environment.

[0102] Parameters used: (Objective lens: 20x / 0.45-Mplan FL N°; Horizontal step size: 0.22μm; Illuminance: 70%; Exposure time / algorithm / quality: 28.5ms / fast / maximum; Gain: 1.5dB).

[0103] Figure 7 shows the surface roughness Sa relative to the keratin layer and its concentration. Higher keratin concentrations result in a lower Sa, indicating a smoother surface. Furthermore, Figure 7bThis study demonstrates the effects of keratin and fructose on the surface roughness of implant materials. In the absence of any coating, Sa is primarily 0.4 to 0.6 μm. The introduction of keratin results in the maintenance of surface micro-roughness, while the introduction of a fructose layer leads to typically out-of-range SLA micro-roughness.

[0104] The micro-roughness measurements of the coated implant, especially the Sa value, were compared between the apex (the tip of the implant) and the sixth thread starting from the apex. Figure 7b In the qualitative inspection, the uncoated surface ( Figure 11a ) and surfaces coated with a protective layer ( Figure 11b The differences between them show that they all have many peaks and valleys of different heights.

[0105] Climate stress cycling applied to Y-TZP materials during packaging

[0106] Table 1. Climatic conditions to be applied (with tolerance limits)

[0107]

[0108] To check whether the protective layer would be damaged under critical conditions during its storage, the cycles in Table 1 were applied after EO sterilization, and the contact angle of the samples was measured and compared with the contact angle of samples that had not undergone the stress cycle.

[0109] like Figure 9 As shown, overall, no effects caused by climate stress (the trend of increasing contact angle, i.e., more hydrophobic) can be detected.

[0110] Kinetic aging test

[0111] Aging parameters were established based on ASTM F 1980-16 - Accelerated aging of sterile barrier systems formedical devices.

[0112] At 2θ = 30°, the higher intensity of the tetragonal phase was measured to a depth of approximately 9.4 μm. The maximum penetration depth in the sample was approximately 20 μm, depending on the specific sample and whether the sample was coated. Measurements were performed from 10 to 40 incident ray radii.

[0113] sterility test

[0114] To test whether the coating provided antimicrobial activity, each sample was incubated in lysogeny broth containing *E. coli*. *E. coli* was pre-cultured one day prior to the onset of infection. At infection, the bacteria were cultured in a lysate of fresh medium to reach 1*10-1. 6 The concentration of bacteria per mL was determined (to test bacterial count, the optical density (OD) was measured at 600 nm and adjusted to 0.001). A control group was added, in which no sample was added. The bacterial count of the control group was measured after 1 day and compared with the relevant sample.

[0115] The bioload assay consisted of incubating samples in LB medium for 7 days. Afterward, the OD value of the medium was recorded to quantify bacterial growth. If bacteria were observed, platening was performed for CFU assay.

[0116] Each protective layer was analyzed using three different replicas.

[0117] Sterility test in BBF SteriXpert

[0118] All samples were EO sterilized prior to analysis. PLs were not removed; instead, the samples were incubated in a medium to test sterilization on the surface of the trays and in the dissolved components of the protective layer.

[0119] The Caso broth was incubated aerobically at 30°C for 14 days. Different culture media were used for each sample. Subsequently, visual analysis was performed according to ISO 11737-2 to check for bacterial growth in the Caso. The microorganisms analyzed are as follows:

[0120] • Aerobic spore-forming bacteria

[0121] ·staphylococcus

[0122] Micrococcus

[0123] Mold

[0124] ·yeast

[0125] In this case, a copy is used for each PL.

[0126] Blood wettability of implants

[0127] As a proof-of-concept, the implant was immersed in blood. Fresh blood was obtained, and the implant was immersed in the blood at a rate of 0.166 mm / s for 10 seconds. After holding the implant in the blood (to a depth of 1.66 mm) for 6 minutes, the uncoated implant was not wetted by the blood medium. The keratin layer rapidly absorbed the blood, resulting in rapid red staining with a spiral pattern from the apex upwards (reaching maximum blood absorption after 1 minute).

[0128] Figure 11a and 11b The blood wettability of the implant is shown after 6 minutes in the DCA instrument (from initial contact to a depth of 1.66 mm from the apex). (a) Uncoated (b) KerL.

Claims

1. A dental implant comprising an implant surface having at least a portion of a contact angle of less than 20°, said implant surface being at least partially covered by a protective layer comprising keratin hydrolysate, said protective layer having a water content of less than 10% by weight.

2. The dental implant according to claim 1, wherein the keratin hydrolysate has an average molecular weight of less than 20,000 Da.

3. The dental implant according to claim 2, wherein the keratin hydrolysate has an average molecular weight of less than 10,000 Da.

4. The dental implant of claim 3, wherein the keratin hydrolysate has an average molecular weight of less than 5,000 Da.

5. The dental implant according to claim 1, characterized in that, The protective layer containing keratin hydrolysates has a thickness of 30 to 200 nm.

6. The dental implant according to claim 3, characterized in that, The protective layer containing keratin hydrolysates has a thickness of 30 to 90 nm.

7. The dental implant according to any one of the preceding claims, characterized in that, The protective layer contains no salt.

8. The dental implant according to any one of claims 1 to 6, characterized in that, The protective layer also contains salt.

9. The dental implant according to claim 8, characterized in that, The protective layer also contains divalent salts.

10. The dental implant according to claim 9, characterized in that, The protective layer also contains MgCl2.

11. The dental implant according to any one of claims 1 to 6, characterized in that, The dental implant is made of ceramic.

12. The dental implant according to claim 11, characterized in that, The dental implant is made of yttrium oxide-stabilized zirconia ceramic.

13. The dental implant according to claim 1, characterized in that, The surface has a surface roughness Sa of 2 to 10 μm.

14. The dental implant according to claim 13, characterized in that, The surface has a surface roughness Sa of 2 to 5 μm.

15. The dental implant according to any one of claims 1 to 6, characterized in that, The implant has a mechanically processed surface.

16. The dental implant according to any one of claims 1 to 6, wherein the protective layer has a water content of less than 1% by weight.

17. A method for preparing a dental implant according to any one of the preceding claims, comprising at least the following steps: a) Provide a surface for the dental implant that has at least a partial contact angle of less than 20°. b) Cover the surface of the dental implant at least partially with a solution or suspension containing keratin hydrolysates, and c) Dry the dental implant to obtain a protective layer.

18. The method according to claim 17, characterized in that, In step b), the surface is covered by immersing the dental implant in an aqueous solution or suspension.

19. The method according to any one of claims 17 to 18, characterized in that, In step c), water is removed by microwave treatment, by airflow, or by drying in a convection oven or vacuum oven.

20. The method according to any one of claims 17 to 18, characterized in that, The aqueous solution or suspension contains 0.1% to 10% by weight / volume of hydrolyzed keratin.

21. The method according to claim 20, characterized in that, The aqueous solution or suspension contains 1 to 5% by weight / volume concentration of hydrolyzed keratin.

22. The method according to any one of claims 17 to 18, characterized in that, The dental implant covered by the protective layer is sterilized with ethylene oxide in a further step.

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