Transgingival dental implant and prosthetic system using such an implant

Abstract

The present invention relates to a transgingival dental implant (1) extending longitudinally (z) along a first smooth section (11) intended to lie flush in the oral cavity of a patient at a first end, referred to as the cervical end (114), and along a second section (10) provided with a male thread, continuing the first section, said threaded section being intended to be screwed into the bone of the jaw of said patient and defining a second end, referred to as the apical end (108), the implant defining a body of revolution along the longitudinal axis (z) and further comprising an inner connection housing (115) that opens out at the first, cervical end (114) and is intended to receive the means (20) for fastening a screw-retained dental component, characterized in that the implant is coated, on at least the smooth section, with a thin layer of zirconia.

Description

TRANSGINGIVAL DENTAL IMPLANT AND PROSTHETIC SYSTEM IMPLEMENTING SUCH AN IMPLANT

[0001] The present invention relates to a transgingival dental implant, as well as to a prosthetic system implementing such an implant, said prosthetic system comprising the implant, a dental component of the "abutment" type and a dental prosthesis.

[0002] Oral implantology is a surgical technique that aims to treat a dental pathology, edentulism, by replacing one or more teeth in edentulous patients with a dental implant. This technique therefore involves implanting an artificial root made of biocompatible materials into the bone of the maxilla or mandible.

[0003] The etiological causes of this pathology can be diverse. The consequences of edentulism depend on its extent depending on whether one or more teeth are missing, and can be diverse. Thus, it can result in a modification of normal physiology, a risk factor for impaired chewing, a deterioration of oral health, a higher prevalence of obesity, an increased risk of cardiovascular diseases and gastrointestinal disorders, an increased risk of chronic inflammation at the gastric level, pancreatic and gastrointestinal cancers, and ulcers, an increased risk of non-insulin-dependent diabetes, a decrease in health-related quality of life, an association between edentulism and sleep-disordered breathing (such as obstructive sleep apnea). The population affected by edentulism is very large but it particularly affects the elderly.

[0004] Implantology can therefore treat single tooth loss, i.e. the loss of one tooth, multiple tooth loss, the loss of several adjacent or non-adjacent teeth, or total tooth loss, or the loss of the entire set of teeth. The implant thus serves as a support for either a crown, a partial or total bridge, or a total removable prosthesis.

[0005] Implantology is a promising alternative to conventional treatments such as tooth-supported bridges or total or partial removable appliances, which can provide a satisfactory response to the dental pathology of edentulism in the short and medium term. Indeed, dental implants provide better results and offer better long-term durability.

[0006] Thus, for the treated patients, implant reconstructions showed an improvement in masticatory function, speech function but also an improvement in overall quality of life.

[0007] The fundamental characteristics of an implant system, as well as the various surgical procedures used and the characteristics of the materials used in oral implantology, will now be explained.

[0008] Thus, an implant system is a triptych of components, including the implant itself, the prosthetic hardware and finally the ancillaries, surgical instruments, necessary for carrying out an implant restoration.

[0009] There are two surgical approaches.

[0010] The approach using the so-called two-stage technique involves the implant being buried in the bone and covered by the gum while the bone heals. Once this bone healing is complete, during a second stage of surgery, the gum is incised above the implant to expose the latter and a transgingival healing screw is fixed there, thus allowing the gum to heal. In this case, the gum will heal around this healing screw and not around the implant. After the gum has healed, this screw is removed and replaced by a prosthetic element on which the crown will be fixed. In this case, we speak of second-intention healing at the gingival level.

[0011] The approach according to the one-stage technique consists of placing an implant of a different design because the latter will have both an endosseous part and a transgingival part. In this configuration, a first-intention gingival healing is obtained around the transgingival part of the implant. The crimp, called epithelial attachment, is definitively acquired in this technique. This technique, where the implant is immediately in relation with the oral cavity, therefore does not involve a second surgical step.

[0012] Furthermore, dental implants are made from perfectly biocompatible biomaterials. The properties of these biomaterials, combined with a specific surface condition, induce, after insertion of the implant into the jawbone, a natural colonization of newly formed bone on the surface of the implant. This process, called osseointegration and highlighted by Professor Per-Ingvar Brånemark, is defined as the direct structural and functional connection between living bone and the surface of an artificial implant.

[0013] The vast majority of dental implants are manufactured from alloyed titanium such as Ti6Al4V Grade 5 or unalloyed titanium such as T60 Grade 4. New ranges of implants machined from sintered zirconia blank have emerged, so that 80% of implants on the market are made of titanium and 20% of zirconia.

[0014] Historically, the titanium range has been the material of choice for implant restorations. However, in some rare cases, this material can be allergic and therefore less well tolerated by the tissues. Due to its metallic color, it also appears unsightly and therefore offers a degraded aesthetic due to its grayish appearance due to the transparency of the gingival tissues.

[0015] There are also ceramic implants which are mainly made of Alumina (Al2O3) or Zirconia (ZrO2). They are not subject to electrochemical corrosion but have a shock resistance, despite the latest advances, ten times lower than that of titanium alloy. Thus, the use of these materials has less scientific hindsight, particularly in terms of mechanical strength, to compete with titanium implants. Indeed, the Young's modulus (or modulus of elasticity) is twice as high for Y-TZP Zirconia obtained by sintering (200 GPa) as for grade 4 titanium (100 GPa).

[0016] This is why the present invention aims to propose a transgingival dental implant benefiting from specific surface treatments, to improve the biological response of each of the tissues present, faced with the foreign body that the implant represents.

[0017] It is from the understanding of the three strategic zones that are the bone zone, the gingival zone and the prosthetic zone, that the inventors sought to optimize the prosthetic system in terms of surface treatments.

[0018] The invention relates in particular to a transgingival dental implant extending longitudinally along a first smooth section intended to be flush in the oral cavity of a patient at a first end called the cervical end, and along a second section provided with a male thread, extending the first section, said threaded section being intended to be screwed into the jawbone of said patient and defining a second end called the apical end, the implant defining a body of revolution along the longitudinal axis and further comprising an internal housing called the connection housing opening at the first end called the cervical end and intended to receive the fixing means of a transscrewed dental component, the implant being coated, on at least the smooth section, with a thin layer of zirconia.

[0019] Optional, complementary or substitutive features of the invention are set out below.

[0020] The thin layer of zirconia is preferably produced using a chemical vapor deposition (CVD) process.

[0021] Alternatively, the thin layer of zirconia is preferably produced using a thermal spray deposition process.

[0022] According to another advantageous embodiment, the thin layer of zirconia produced by the chemical vapor deposition process or by thermal spraying is a stabilized yttria zirconia doped with alumina.

[0023] Preferably, the thin layer of zirconia produced by the chemical vapor deposition process or by thermal spraying is doped with inorganic antimicrobial agents having high antibacterial activity, excellent biocompatibility and sufficient stability, such as silver, copper, zinc, fluorine, calcium, nitrogen.

[0024] Even more preferably, the thin layer of zirconia produced by the chemical vapor deposition process or by thermal spraying is doped with inorganic antimicrobial agents in metallic, ionic or oxide form, such as silver (Ag, Ag + , Ag2O), copper (Cu, Cu 2+ , CuO), or even zinc (Zn, Zn 2+ , ZnO).

[0025] The thin layer of zirconia preferably has a thickness between 10 and 100 microns.

[0026] The thin layer of zirconia preferably has an arithmetic mean roughness, noted Ra, less than 0.50 microns, preferably less than 0.20 microns, even more preferably less than 0.10 microns.

[0027] The smooth section preferably has a portion adjacent to the threaded section, intended to be buried in the jaw bone of said patient.

[0028] The adjacent portion is preferably cylindrical or truncated cone-shaped, and extends longitudinally over a length of between 1 and 4 mm.

[0029] The second threaded section preferably has a surface condition such that the arithmetic mean roughness, noted Ra, is between 1.2 and 1.8 microns, preferably of the order of 1.5 microns.

[0030] The length of the threaded section is preferably of the order of twice the length of the smooth section.

[0031] The invention also relates to a prosthetic system comprising a transgingival dental implant in accordance with one embodiment of the invention, as well as a screw-retained dental component of the abutment type, and a dental prosthesis.

[0032] Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments which are in no way limiting, and the following appended drawings:

[0033] This figure represents a schematic exploded view of a prosthetic system according to one embodiment of the invention.

[0034] This figure represents a detailed schematic view following a cross-section of an assembled prosthetic system and in accordance with an embodiment of the invention.

[0035] This figure represents a schematic view following a cross-section of a prosthetic system according to an embodiment of the invention, and implanted in the jaw of a patient.

[0036] In relation to figures 1 and 2, the prosthetic system according to the invention comprises a transgingival dental implant 1, as well as a screw-retained dental component 2 of the abutment type, and a dental prosthesis 3.

[0037] The transgingival dental implant extends longitudinally along a z axis and comprises a first smooth section 11 intended to be flush in the oral cavity of a patient at a first end called the cervical end 114 of the implant.

[0038] Smooth means that the first section is completely free of roughness. In other words, it does not have, for example, grooves, ribs, threads, and has low roughness.

[0039] The implant also comprises a second section 10 provided with a male thread, extending the first section, said threaded section being intended to be screwed into the jaw bone of said patient and defining the second end called the apical end 108 of the implant.

[0040] The implant defines a body of revolution along the longitudinal axis z and may further comprise a so-called connection appendage 113 extending the first so-called cervical end 114, as well as an internal so-called connection housing 115 opening at the level of the first so-called cervical end 114.

[0041] The so-called connecting appendage 113 serves to strengthen the connection between the implant and a screw-retained dental component 2, such as an abutment, at the part of the prosthetic system that emerges into the patient's oral cavity. Once the implant is installed in the patient's jaw, the abutment is screwed into the implant and the dental prosthesis 3 is fixed (usually by gluing) to the abutment. This creates the prosthetic system.

[0042] The housing 115 is intended to receive the fixing means 20, such as a screw, of a screw-retained dental component 2, such as an abutment.

[0043] According to the principle of the invention, the implant 1 is coated, on at least the smooth section 11, with a thin layer of zirconia, preferably a thin layer of zirconia stabilized with 8% by mass of yttria (yttria-containing zirconia).

[0044] Advantageously, the arithmetic mean roughness, noted Ra, is less than 0.50 microns, preferably less than 0.20 microns, even more preferably less than 0.10 microns.

[0045] The production of deposits is preferably obtained by dry processing.

[0046] According to a certain embodiment also preferred, the thin layer of zirconia is produced according to a thermal spray deposition process. The term "thermal spray deposition" refers to processes in which solid materials are decomposed into fine particles in a liquid or pasty state in a gas flow to form a coating by stacking on a substrate. The carrier gas is used to accelerate and transport to the substrate fine particles (typically 5 to 100 micrometers) which can be in a liquid, pasty or even solid state. This carrier gas can also be an enthalpy source, allowing these particles to be heated to the melting point. Other processes use an electric arc to melt the material. The particles thus projected onto the substrate are crushed depending on their speed, physical state, temperature or other forming lamellae (or splats in English).

[0047] The accumulation and stacking of the lamellae on the substrate allows the coating to be produced.

[0048] According to another also preferred embodiment, the thin layer of zirconia is produced using a CVD chemical vapor deposition process. Chemical vapor deposition makes it possible to deposit films of solid materials by epitaxy on the surface of a substrate during the vapor phase of a controlled chemical reaction.

[0049] CVD deposition is a fast and versatile method for supporting film growth, allowing the generation of pure coatings with uniform thickness and controlled porosity, even on complex or profiled surfaces. In addition, CVD can be applied selectively to specific areas.

[0050] Advantageously, the thin layer of zirconia is doped with cations, and preferentially doped with metal ions such as silver ions Ag +, copper ions Cu 2+ or zinc ions Zn 2+ The toxic effect of metal ions, or oligodynamic effect, on microorganism cells, even at relatively low concentrations, drastically reduces the presence and adhesion of microorganisms harmful to the longevity of the implant.

[0051] Alternatively or in addition, the thin zirconia layer can be doped with Alumina.

[0052] Likewise, preferably, the thin layer of zirconia has a thickness of between 10 and 100 microns.

[0053] The inventors in fact favor obtaining a sufficiently thick (several tens of microns) and homogeneous layer, particularly on the portion of the smooth section which is exposed in the oral cavity, so that the white precursors can be visible to the naked eye, without any transparency effect. The grayish color of the implant, generally titanium or titanium alloy, is thus masked.

[0054] The inventors also prioritize obtaining a sufficiently thick layer over the entire implant.

[0055] In this case, the entire implant, made of alloyed or unalloyed titanium, is exposed to one or more precursors in liquid or gas phase, which react on the surface of the implant 1 in a reaction chamber to generate the desired doped zirconia deposit.

[0056] The resulting zirconia deposit is solid, non-porous, high-performance, and highly pure. This zirconia deposit also incorporates the encapsulation of metal cations, such as silver ions or copper ions. The toxic effect of metal ions, or oligodynamic effect, on microorganism cells, even at relatively low concentrations, drastically reduces the presence and adhesion of microorganisms that are harmful to the longevity of the implant. The zirconia layer thus reduces the risk of periodontal disease and prevents the onset of peri-implantitis.

[0057] The hard outer shell of zirconia chemically bonded to the implant surface forms a top layer of corrosion protection. This layer prevents air and moisture from coming into contact with the underlying titanium implant. Oxygen (the cathode) and moisture (the electrolyte) are out of the equation, the oxidation reaction cannot occur and therefore, corrosion of the titanium cannot occur.

[0058] The zirconia protection has a high degree of hardness and a very low coefficient of friction. In other words, the zirconia layer allows the implant to insert into the tissues, thus reducing the friction force and therefore the risk of bone heating that can induce bone necrosis.

[0059] Zirconia has a very low thermal conductivity, of the order of 2.5 W m −1 K −18Its addition to the substrate forms an effective thermal barrier that limits thermal exposure of surrounding tissues. This insulating barrier thus helps reduce tissue heating during implant placement.

[0060] Due to its natural color and smooth surface, the zirconia layer gives the implant a shiny appearance and durability. This aspect is even more important in the ZG attachment zone of the gingival tissues. The natural pearly white appearance obtained is quite comparable to the color of a tooth and its root, proving to be an undeniable aesthetic asset for the patient.

[0061] Advantageously, the smooth section 11 has a portion 116 adjacent to the threaded section 10, intended to be buried in the jaw bone of said patient.

[0062] Preferably, the adjacent portion 116 is cylindrical or frustoconical in shape (with a taper oriented towards the apical end), and extends over a length of between 1 and 4 mm.

[0063] This portion 116 promotes the establishment of distant osteogenesis and therefore corticalization. New bone formation, secondary (biological) stability, will occur from the adjacent bone surface, resulting in the formation of woven bone. The newly formed woven bone will then mature and remodel. The organization first becomes lamellar and then Haversian with permanent remodeling. As remodeling and maturation progress, the bone becomes increasingly mechanically resistant.

[0064] Preferably, the second threaded section 10 has a surface condition such that the arithmetic mean roughness, denoted Ra, is between 1.2 and 1.8 microns, preferably of the order of 1.5 microns.

[0065] Such a rough surface condition can be obtained, in particular when the second threaded section 10 is coated with a thin layer of zirconia, by means of subtractive techniques such as sandblasting and acid etching, these techniques being able to be combined.

[0066] This surface condition has the advantage of promoting contact osteogenesis and bone trabeculation which promotes healing of the area where the screwing is carried out.

[0067] In summary and in relation to figures 2 and 3, the implant according to the invention and preferred characteristics, is provided with a smooth section 11 coated with a thin layer of zirconia having a very low roughness over a contact depth ZL in the direction of the apex, first with the gingival tissues ZG then with the bone zone ZO and in particular with the crestal bone Oc.

[0068] The anchoring of the implant is further ensured by means of a threaded section 10 having a preferably higher roughness over a contact depth ZR in the direction of the apex, with the bone zone ZO and in particular with the spongy bone Os.

[0069] The anchoring of the smooth section 11 in the crestal bone Oc by means of the adjacent portion 116 makes it possible to protect the gingival attachment zone GA consisting of the peri-implant connective tissue T covered by the juxta-implant epithelium E. The gingival attachment zone GA located between the marginal gingiva GM and the alveolar mucosa MA is in fact a particularly sensitive zone.

[0070] Preferably, the length ZR of the threaded section 10 is of the order of twice the length ZL of the smooth section 11, the implant being buried over the entire depth corresponding to the gingival zone ZG and the bone zone ZO.

[0071] Concerning the dimensions, the implants can present, in compliance with the ZR / ZL ratio of the order of 2, the following dimensions:ZR length of the threaded sectionZL length of the smooth section6 mm3 mm7.5 mm3.5 mm8.5 mm4.5 mm10 mm5 mm11.5 mm5.5 mm

[0072] The embodiments described below being in no way limiting, it will be possible in particular to consider variants of the invention comprising only a selection of the described characteristics, isolated from the other described characteristics (even if this selection is isolated within a sentence comprising these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0073] Note that the various features, forms, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Claims

Transgingival dental implant (1) extending longitudinally (z) along a first smooth section (11) intended to be flush in the oral cavity of a patient at a first end called cervical (114), and along a second section (10) provided with a male thread, extending the first section, said threaded section being intended to be screwed into the jawbone of said patient and defining a second end called apical (108), the implant defining a body of revolution along the longitudinal axis (z) and further comprising an internal housing called connection (115) opening at the first end called cervical (114) and intended to receive the fixing means (20) of a transscrewed dental component, characterized in that the implant is coated, on at least the smooth section, with a thin layer of zirconia. Transgingival dental implant according to claim 1, characterized in that the thin layer of zirconia is produced using a chemical vapor deposition (CVD) process. Transgingival dental implant according to claim 1, characterized in that the thin layer of zirconia is produced using a thermal spray deposition process. Transgingival dental implant according to claim 2 or 3, characterized in that the thin layer of zirconia produced by a chemical vapor deposition process or by thermal projection is doped, preferably with cations. Transgingival dental implant according to claim 4, characterized in that the thin layer of zirconia produced by a chemical vapor deposition process or by thermal spraying is doped with inorganic antimicrobial agents having high antibacterial activity, excellent biocompatibility and sufficient stability, such as silver, copper, zinc, fluorine, calcium, nitrogen. Transgingival dental implant according to the preceding claim, characterized in that the thin layer of zirconia produced by a chemical vapor deposition process or by thermal spraying is doped with inorganic antimicrobial agents in metallic, ionic or oxide form, such as silver (Ag, Ag + , Ag2O), copper (Cu, Cu 2+ , CuO), or even zinc (Zn, Zn 2+ , ZnO). Transgingival dental implant according to one of the preceding claims, characterized in that the thin layer of zirconia produced by a chemical vapor deposition process or by thermal projection is a stabilized yttria zirconia doped with alumina. Transgingival dental implant according to any one of the preceding claims, characterized in that the thin layer of zirconia has a thickness of between 10 and 100 microns. Transgingival dental implant according to any one of the preceding claims, characterized in that the thin layer of zirconia has an arithmetic mean roughness, noted Ra, of less than 0.50 microns, preferably less than 0.20 microns, even more preferably less than 0.10 microns. Transgingival dental implant according to any one of the preceding claims, characterized in that the smooth section (11) has a portion (116) adjacent to the threaded section (10), intended to be buried in the jawbone of said patient. Transgingival dental implant according to the preceding claim, characterized in that the adjacent portion (116) is cylindrical or frustoconical in shape, and extends longitudinally over a length of between 1 and 4 mm. Transgingival dental implant according to any one of the preceding claims, characterized in that the second threaded section (10) has a surface condition such that the arithmetic mean roughness, noted Ra, is between 1.2 and 1.8 microns, preferably of the order of 1.5 microns. Transgingival dental implant according to any one of the preceding claims, characterized in that the length of the threaded section (10) is of the order of twice the length of the smooth section (11). Prosthetic system comprising a transgingival dental implant according to any one of claims 1 to 13, as well as a screw-retained dental component (2) of the abutment type, and a dental prosthesis (3).

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