TRANSGINGIVAL DENTAL IMPLANT AND PROSTHETIC SYSTEM IMPLEMENTING 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 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. Figure 1

Description

Title of the invention: TRANSGINGIVAL DENTAL IMPLANT AND PROSTHETIC SYSTEM IMPLEMENTING SUCH AN IMPLANT

[0001] The present invention relates to a transgingival dental implant, as well as 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 by placing a dental implant. This technique therefore consists of 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 toothlessness 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 mastication, 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 toothlessness and sleep-disordered breathing (such as obstructive sleep apnea). The population affected by toothlessness is very large but it particularly affects the elderly.

[0004] Implantology thus makes it possible to treat single edentulism, i.e. the loss of one tooth, multiple teeth, or the loss of several adjacent or non-adjacent teeth, or total teeth, or the loss of the entire set of teeth. The implant thus serves as a support, either for a crown, or for a partial or total bridge, or for 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 give better results and have better long-term performance.

[0006] Thus, for the treated patients, the implant reconstructions showed an improvement in masticatory function, speech function but also a 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, grouping the implant itself, the prosthetic fittings and finally ancillaries, surgical instruments, necessary for carrying out an implant restoration.

[0009] There are two surgical approaches.

[0010] The approach according to the so-called two-stage surgical technique implies that the implant is buried in the bone and covered by the gum during the time of bone healing. Once this bone healing is complete, during a second surgical stage, 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 gingival healing, 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 stage of surgery.

[0012] Furthermore, dental implants are manufactured 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 Brânemark, 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 Grade 5 Ti6A14V or unalloyed titanium such as Grade 4 T60. 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 certain rare cases this material can prove to be allergic and therefore less well tolerated by the tissues. Due to its metallic color, it appears to more 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 (A12O3) 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 object of the present invention is to propose a transgingival dental implant benefiting from specific surface treatments, to improve the biological response of each of the tissues present, when faced with the foreign body represented by the implant.

[0017] It is from the understanding of the three strategic zones which 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] The thin layer of zirconia is preferably produced using a thermal spray deposition process.

[0022] The thin layer of zirconia produced by the chemical vapor deposition process or by thermal projection is preferentially doped with cations.

[0023] The thin layer of zirconia produced by the chemical vapor deposition process is preferentially doped with silver ions Ag+.

[0024] The thin layer of zirconia preferably has a thickness of between 10 and 100 microns.

[0025] The thin layer of zirconia preferably 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.

[0026] The smooth section preferably has a portion adjacent to the threaded section, intended to be buried in the jaw bone of said patient.

[0027] The adjacent portion is preferably cylindrical or frustoconical in shape, and extends longitudinally over a length of between 1 and 4 mm.

[0028] The second threaded section preferably 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.

[0029] The length of the threaded section is preferably of the order of twice the length of the smooth section.

[0030] The invention also relates to a prosthetic system comprising a transgingival dental implant in accordance with an embodiment of the invention, as well as a screw-retained dental component of the abutment type, and a dental prosthesis.

[0031] 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:

[0032] [Fig.l] This figure represents a schematic exploded view of a prosthetic system according to an embodiment of the invention.

[0033] [Fig.2] This figure represents a detailed schematic view along a cross-section of an assembled prosthetic system conforming to an embodiment of the invention.

[0034] [Fig.3] This figure represents a schematic view along a cross-section of a prosthetic system according to an embodiment of the invention, and implanted in the jaw of a patient.

[0035] In relation to figures 1 and 2, the prosthetic system according to the invention comprises a transgingival dental implant 1, as well as a transscrewed dental component 2 of the abutment type, and a dental prosthesis 3.

[0036] 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.

[0037] 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.

[0038] The implant defines a body of revolution along the longitudinal axis z and can further comprise a so-called connecting appendage 113 extending the first so-called cervical end 114, as well as an internal so-called connecting housing 115 opening at the level of the first so-called cervical end 114.

[0039] The so-called connection appendage 113 makes it possible to reinforce the connection between the implant and a screw-retained dental component 2, such as an abutment, at the level of the part of the prosthetic system which emerges in 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 (generally by gluing) to the abutment. The prosthetic system is thus obtained.

[0040] The housing 115 is intended to receive the fixing means 20, such as a screw, of a transscrewed dental component 2, such as an abutment.

[0041] 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 at 8% by mass of yttrium.

[0042] 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.

[0043] The production of deposits is preferably obtained by dry process treatments.

[0044] According to a certain embodiment which is also preferred, the thin layer of zirconia is produced using a thermal spray deposition process. The term "thermal spray deposition" refers to processes in which solid materials are broken down 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 fine particles (typically 5 to 100 micrometers) to the substrate, which may be in a liquid, pasty or even solid state. This carrier gas can also be an enthalpy source, making it possible to heat these particles 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).

[0045] The accumulation and stacking of the lamellae on the substrate makes it possible to produce the coating.

[0046] 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.

[0047] CVD deposition provides a rapid and versatile method of supporting the film growth, allowing the generation of pure coatings of uniform thickness and controlled porosity, even on complex or profiled surfaces. In addition, it is possible to apply CVD selectively to specific areas.

[0048] Advantageously, the thin layer of zirconia is doped with cations, and preferentially doped with silver ions Ag+. The toxic effect of the metal ions, or oligodynamic effect, on the cells of microorganisms, even at relatively low concentrations, drastically reduces the presence and adhesion of microorganisms harmful to the durability of the implant.

[0049] Similarly, the thin layer of zirconia has a thickness of between 10 and 100 microns.

[0050] The inventors in fact favor obtaining a sufficiently thick (several tens of microns) and homogeneous layer, in particular on the portion of the smooth section which is exposed in the oral cavity, so that the white colored 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.

[0051] The inventors also favor obtaining a sufficiently thick layer over the entire implant.

[0052] 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.

[0053] The zirconia deposit obtained is solid, non-porous, high-performance, and of high purity. 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 harmful to the durability of the implant. The zirconia layer thus reduces the risk of periodontal diseases and prevents the occurrence of peri-implantitis.

[0054] 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 take place.

[0055] 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 be inserted into the tissues, thus reducing the friction force and therefore the risk of bone heating which could induce bone necrosis.

[0056] Zirconia has a very low thermal conductivity, of the order of 2.5 WK lx. Its addition to the substrate forms an effective thermal barrier which limits the thermal exposure of the surrounding tissues. This insulating barrier thus makes it possible to reduce heating of the tissues during the placement of the implant.

[0057] 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 completely comparable to the color of a tooth and its root, proving to be an undeniable aesthetic asset for the patient.

[0058] 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.

[0059] 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.

[0060] This portion 116 promotes the establishment of remote 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Concerning the dimensions, the implants can have, in compliance with the ZR / ZL ratio of the order of 2, the following dimensions: Length ZR of the threaded section Length ZL of the smooth section 6 mm 3 mm 7.5 mm 3.5 mm 8.5 mm 4.5 mm 10 mm 5 mm 11.5 mm 5.5 mm

[0069] 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 characteristics described, isolated from the other characteristics described (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.

[0070] Note that the various features, forms, variants and embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive.

Claims

Claims

1. 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, the thin layer of zirconia being produced by a chemical vapor deposition process or by thermal spraying,and being doped with metal cations, so that the toxic effect of metal ions, or oligodynamic effect, on the cells of microorganisms even at relatively low concentrations, drastically reduces the presence and adhesion of microorganisms harmful to the durability of the implant.

2. Transgingival dental implant according to the preceding claim, characterized in that the thin layer of zirconia produced by the chemical vapor deposition process is doped with silver ions Ag+.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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).

9. Prosthetic system comprising a transgingival dental implant according to any one of claims 1 to 8, as well as a transscrewed dental component (2) of the abutment type, and a dental prosthesis (3).

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