FR3148902A1 - TRANSGINGIVAL DENTAL IMPLANT AND PROSTHETIC SYSTEM USING SUCH AN IMPLANT - Google Patents

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 jaw bone 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 fixing means (20) of a transscrewed dental component, characterized in that the second threaded section has a central portion projecting relative to the average diameter of the smooth section. Figure 1

Description

TRANSGINGIVAL DENTAL IMPLANT AND PROSTHETIC SYSTEM USING SUCH AN IMPLANT

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 “pillar” type and a dental prosthesis.

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.

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 in 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.

Implantology thus makes it possible to treat single edentulism, i.e. the loss of one tooth, multiple edentulism, i.e. the loss of several adjacent or non-adjacent teeth, or total edentulism, i.e. 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.

Implantology is a promising alternative to possible classic 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 durability.

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

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.

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.

There are two surgical approaches.

The approach according to the so-called two-stage surgical technique involves the implant being buried in the bone and covered by the gum during the bone healing time. Once this bone healing is complete, during a second surgical step, the gum is incised above the implant to expose the latter and to fix a transgingival healing screw, 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.

The approach according to the one-stage technique consists of placing an implant of a different design because the latter will have both an endosteal part and a transgingival part. In this configuration, a first-intention gingival healing is obtained around the transgingival part of the implant. The setting, 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.

Furthermore, dental implants are made of 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.

The vast majority of dental implants are manufactured from alloyed titanium such as Grade 5 Ti6Al4V 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.

Dental implants generally have a threaded section intended to ensure mechanical anchoring in the patient's bone. Screwing this section to allow this anchoring therefore requires perfect control of all the parameters.

For example, over-drilling of the implant site can reduce primary stability.

Similarly, an inadequate biomechanical environment causes mesenchymal cells arriving at the implant site to differentiate into the fibroblastic lineage and not into the osteoblastic lineage.

For example, when bone volume is insufficient, it is necessary to fill the bone gap (bone graft, guided bone regeneration) and adapt the thread to avoid fibrous encapsulation.

It therefore appeared necessary to minimize the invasive nature of the thread while ensuring sufficient anchoring.

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 threaded section of a transgingival dental implant.

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 jaw bone 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 a connection housing opening at the first end called the cervical end and intended to receive means for fixing a transscrewed dental component, characterized in that the second threaded section has a central portion projecting relative to the average diameter of the smooth section.

Optional, complementary or substitute features of the invention are set forth below.

The diameter of the implant at the thread crests of the central protruding portion is preferably greater than or equal to 1.5 times the diameter of the implant at the thread roots.

The thread of the second section is preferably carried by a truncated surface whose generator forms a half-angle at the apex α between 3 and 14 degrees.

The first section is also preferentially carried by a truncated surface of the same generator.

The portions of the thread on either side of the central portion are preferably flush and advantageously have a convex envelope for the portion located on the side of the apical end, and a concave envelope for the portion located on the side of the smooth section.

The load-bearing flanks and the thread engagement flanks are preferably inclined at an angle with the normal to the generator of between 5 and 25 degrees.

The sum of the angles with the normal to the generator 106 of a load-bearing flank and an engagement flank is preferably between 15 and 30 degrees and advantageously of the order of 15 degrees.

The diameter of the implant at the maximum height hmax of the thread is preferably equal to the diameter of the implant at its first end, called the cervical end.

The ZR length of the threaded section is preferably of the order of two thirds of the total length of the implant.

The thread of the second section preferably comprises interruptions forming at least one, advantageously three helices extending along the longitudinal axis, and with an angle advantageously between 5 and 20 degrees.

The bottoms of the nets preferably have a groove.

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 transscrewed dental component of the abutment type, and a dental prosthesis.

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:

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

This figure represents a detailed schematic view following a sagittal section of an assembled prosthetic system conforming to an embodiment of the invention.

This figure represents a schematic view following a sagittal section of a prosthetic system conforming to an embodiment of the invention, and implanted in the jaw of a patient.

This figure represents a perspective view from above of an implant according to one embodiment of the invention.

This figure represents a perspective view from below of an implant according to one embodiment of the invention.

This figure represents a side view of an implant according to one embodiment of the invention.

This figure represents a view following a longitudinal section of the threaded section of an implant according to an embodiment of the invention.

This figure represents a bottom view of an implant according to one embodiment of the invention.

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.

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 cervical 114 of the implant.

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 apical 108 of the implant.

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 housing 115 called connection which opens at the level of the first so-called cervical end 114.

The so-called connecting appendix 113 is used 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 gives the prosthetic system.

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.

According to the principle of the invention, the second threaded section has, in a longitudinal section along a plane passing through the z axis, a central portion projecting relative to the average diameter of the smooth section.

It is understood that the anchoring zone carried by the central portion of said threaded section is wider than the rest of the implant, the rest of the implant being made up of the smooth portion 11 and the portions of the thread arranged on either side of the central portion.

The principle of the invention is to minimize the size of the implant at the level of the smooth section and on either side of the central portion and to present on the other hand a large contact surface at the level of the central portion of the thread with a significant height for the threads.

Preferably and with reference to figures 6 and 7, the diameter of the implant at the level of the thread crests 103 of the projecting central portion is between 1.5 and 2 times the diameter of the implant at the level of the thread roots 101.

Thus, the portions of the thread arranged on either side of the central portion are leveled, so that the height of the threads decreases from the central portion towards the apical end 108 and towards the cervical end 114.

Advantageously, the portion of the thread on the side of the apical end 108 is flush and has a convex envelope, so as to facilitate first of all, the centering and insertion of the apex into the drilling or the natural alveolus, then the screwing. Finally, this convex envelope profile allows a better geometric correspondence with the predominantly conical natural alveolus (in the case of a post-extraction installation), and with the drilling well created in the bone zone by a sequence of conical or stepped drills. This convex envelope can have a radius between 4 and 8 mm, and preferably of the order of 6.5 mm for all the variations of the implant range.

Also advantageously, the portion of the thread on the smooth section side is flush and has a concave envelope, so as to minimize the invasive nature of the implant in the bone zone ZO close to the crestal bone Oc. This concave envelope may have a radius of between 1 and 4 mm. This value is to be correlated with the implant lengths of the range in order to maintain a sufficient number of complete turns guaranteeing the mechanical anchoring of the threaded section 10 in the bone zone ZO.

The threaded section has an oblong shape with the threads thus leveled.

In relation to Figures 2 and 3, it can be seen that the implant according to the invention is provided with a smooth section 11 which extends over a contact depth ZL towards the apex, first with the gingival tissues ZG then with the bone zone ZO and in particular with the crestal bone Oc.

The anchoring of the implant is further ensured by means of the threaded section 10 on a contact depth ZR towards the apex, with the bone zone ZO consisting mainly of the spongy bone Os.

The anchoring of the smooth section 11 in the crestal bone Oc with a width less than that of the central portion of the threaded section 10, 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.

According to figures 6 and 7, preferably and to facilitate the screwing of the implant, the thread of the second section is carried by a truncated surface whose generator 106 forms a half-angle at the apex α of between 3 and 14 degrees, varying according to the length of the implant of the range to be taken into consideration.

Also preferably, the bottoms 101 of the threads are also inclined to follow a conicity substantially equal to the conicity defined by the generator 106.

Advantageously, the first section can also be carried by a truncated surface of the same generator 106.

The first end, called cervical 114, may have a widening of between 4 and 7 mm in order to seal in an improved manner the perforation of the marginal gingiva GM caused by the placement of the implant or the natural alveolus in the case of a post-extraction implant placement. This widening plays the role of a sealing obturator against the oral environment and its bacterial flora. This widening also makes it possible to ensure a stable base for fixing the dental component of the abutment type 2 and for the prosthesis 3.

According to this configuration, the diameter of the implant at the maximum height hmax of the thread can advantageously be equal to the diameter of the implant at its first end called cervical 114, said first end therefore having a widening so as to seal the perforation of the marginal gingiva GM caused by the placement of the implant or the natural alveolus in the case of a post-extraction implant placement. Depending on the variation of the implants in the range, this diameter can take values preferably between 4 and 7 mm.

According to a preferred aspect, the second section comprises trapezoidal threads with constant pitch.

The load-bearing flanks 104 of the thread can then be inclined at an angle with the normal to the generator 106 of between 5 and 25 degrees.

Similarly, the engagement flanks 102 of the thread can be inclined at an angle with the normal to the generator 106 of between 5 and 25 degrees.

Preferably, the sum of the angles with the normal to the generator 106 of a load-bearing flank and an engagement flank must be between 15 and 30 degrees and preferably of the order of 15 degrees in order to favor a size effect, instead of a compaction effect, when screwing into the bone zone.

According to another preferred aspect and in relation to figures 4, 5 and 8, the thread of the second section comprises interruptions forming at least one helix, preferably three helices 107, extending along the longitudinal axis z. The conical helix angle varies according to the length and diameter of the implant and is between 5 and 20 degrees. The revolution of the helix varies from 0.3 to 0.5 according to the length of the implant, the shorter the implant the lower the revolution of the helix will be. These helices make it possible to evacuate bone chips when screwing the implant.

According to yet another preferred aspect, the thread bottoms 101 are hollowed out by a groove 105, which makes it possible on the one hand to increase the contact surface with the reconstituted bone during osteogenesis, and on the other hand to improve the circulation and distribution of blood tissue over the entire surface of the rough zone, by a phenomenon of capillarity and surface hydrophilicity.

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.

Such a rough surface condition can be achieved by means of subtractive techniques such as sandblasting and acid etching, these techniques being able to be cumulative.

This surface condition has the advantage of promoting contact osteogenesis and bone trabeculation which promotes healing of the area where the screwing is performed.

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.

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 section Length ZL of the smooth section 6 mm 3 mm 7.5 mm 3.5mm 8.5 mm 4.5 mm 10 mm 5 mm 11.5 mm 5.5 mm

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 features described, isolated from the other features described (even if this selection is isolated within a sentence comprising these other features), if this selection of features 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 feature, 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.

It should be noted 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 (12)

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 jaw bone 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 fixing means (20) of a transscrewed dental component, characterized in that the second threaded section has a central portion projecting relative to the average diameter of the smooth section. Transgingival dental implant according to claim 1, characterized in that the diameter of the implant at the thread crests (103) of the projecting central portion is between 1.5 and 2 times the diameter of the implant at the thread roots (101). Transgingival dental implant according to claim 1 or 2, characterized in that the thread of the second section is carried by a truncated cone-shaped surface whose generator (106) forms a half-angle at the apex α of between 3 and 14 degrees. Transgingival dental implant according to claim 3, characterized in that the first section is also carried by a truncated cone-shaped surface of the same generator (106). Transgingival dental implant according to any one of the preceding claims, characterized in that the portions of the thread on either side of the central portion are leveled and have a convex envelope for the portion located on the side of the apical end, and a concave envelope for the portion located on the side of the smooth section. Transgingival dental implant according to claim 4, characterized in that the load-bearing flanks (104) and the engagement flanks (102) of the thread are inclined at an angle with the normal to the generator (106) of between 5 and 25 degrees. Transgingival dental implant according to the preceding claim, characterized in that the sum of the angles with the normal to the generator 106 of a load-bearing flank and an engagement flank is between 15 and 30 degrees and preferably of the order of 15 degrees. Transgingival dental implant according to any one of the preceding claims, characterized in that the diameter of the implant at the maximum height hmax of the thread is equal to the diameter of the implant at its first end called cervical (114). Transgingival dental implant according to any one of the preceding claims, characterized in that the length ZR of the threaded section (10) is of the order of two thirds of the total length of the implant. Transgingival dental implant according to any one of the preceding claims, characterized in that the thread of the second section comprises interruptions forming at least one, preferably three helices (107) extending along the longitudinal axis (z), and at an angle preferably between 5 and 20 degrees. Transgingival dental implant according to any one of the preceding claims, characterized in that the thread bases (101) comprise a groove (105). Prosthetic system comprising a transgingival dental implant according to any one of claims 1 to 11, as well as a transscrewed dental component (2) of the abutment type, and a dental prosthesis (3).