FR2690069A1 - Advanced multi-block dental implant and accessories. - Google Patents

Abstract

A composite dental implant for placing and holding a prosthesis (19) on a bone site. Said implant includes a main body (7) having a shank (5) which is radially expandable by means of longitudinal slots so that it can be engaged and secured in an implanted root (1). A pressure member (17) and a guiding assembly are provided in the shank to lock said shank into the root. Said implant may thus be accurately and firmly fixed in said implanted root (1) and readily withdrawn if required.

Description

IMPROVED MULTIBLOCK DENTAL IMPLANT
AND ACCESSORIES
The invention relates to a multiblock dental implant, intended for placing and maintaining a dental prosthesis on a bone site. It extends to accessories of this implant: instrument intended to facilitate its installation, provisional protective element before fitting the prosthesis.

 Dental implantology is moving more and more towards multiblock implants which consist of two separate parts, placed successively: on the one hand, an implant root is formed by a tubular part which is anchored in the bone site, on the other hand, a suprastructure made up of a fixation tail in the implant root and a false prosthesis support stump. In so-called straight implants, the abutment and the fixation tail have collinear axes, while in so-called angulated implants, the axes of these elements form an angle of up to 300.

 The implant root is first anchored in the bone site by screwing or any other means (patents DE 1,961,531, EP 0.114.955, US 3,708,883 ...), then the suprastructure is subject to said implant root by means of its fixing tail so that the abutment comes to be in the appropriate position.

This fixation of the tail in the implant root is essentially carried out by two conventional techniques.

 Firstly, the tail of the suprastructure being formed by a smooth rod, this is definitively sealed in the tubular implant root by means of a cement; however, in case of clinical problems, it is no longer possible to remove the suprastructure.

 In the other known fixing technique, the tail of the suprastructure is screwed into the implant root by means of a thread and a tapping which are provided on these elements (cf. US Pat. No. 3,589,011).

The suprastructure is then removable, but its positioning is imprecise, both in the longitudinal direction (along the axis of the implant), because it is difficult, during screwing, to determine the limit of tightening stop, as regards the orientation of said suprastructure around its axis, since this orientation conditioned by the end of screwing position is very random; this angular imprecision constitutes a serious defect in the case of angled implants which are very delicate to position in an appropriate manner with this type of fixation.

Patent FR 90.05938 in the name of the applicant describes a multiblock implant which eliminates these defects. In this implant
(a) the suprastructure has a hollow core which extends over its entire length and opens at the free end of the abutment, a converging ramp being provided at the free end of the tail,
(b) said tail is provided with slots extending from its free end over part of its length, in order to delimit several sectors,
(c) said tail contains a mechanical pressure member, movable between an active position where this member exerts pressure on the converging ramp tending to separate the sectors and a passive position where said sectors remain free,
(d) maneuvering means are associated with the pressure member in order to allow said member to be displaced longitudinally towards its active position and to block it under pressure against the converging ramp.

 Such an implant allows precise fixation of the suprastructure on the implant root, while preserving the ability to withdraw this suprastructure if necessary.

 The present invention relates to an improved implant of the above-mentioned type. It proposes to improve the fixation of the suprastructure on the implant root and in particular to increase the precision of this fixation along the longitudinal axis of the implant (depth of penetration of the tail into the implant root perfectly determined, improved locking in this position both in rotation and in longitudinal translation).

 Another objective of the invention is to facilitate the handling of the implant and the laying operations.

To this end, the implant of the aforementioned type is characterized in that
(e) the implant root has in its internal bore a relief-or hollow structure longitudinally positioned to be located at the level of the sectors of the tail of the suprastructure when the latter is in place in the implant root,
(f) the tail of the suprastructure has externally at its sectors, a hollow-or relief-structure, combined with the structure of the implant root and adapted to cooperate with the latter when the tail is in place in the implant root,
(g) tail slots are adapted to allow sectors to undergo
on the one hand, in the passive position of the pressure member, a radial retraction allowing them to retract in the centripetal direction to a depth at least equal to the thickness of the relief structure of the implant root (or tail),
on the other hand, a radial expansion, in the active position of the pressure member,
(h) the combined hollow and relief structures of the tail and the implant root are profiled to ensure the centripetal retraction of the sectors when the tail is placed in the implant root or when it is removed, the organ pressure in the passive position.

 In the improved implant according to the invention, the tubular implant root is anchored in the bone site in a traditional manner, in particular by screwing; said implant root is in particular provided for this purpose with an external thread in order to operate this screwing, this thread possibly being able to be self-tapping. The suprastructure is fixed on the implant root thus anchored, by introducing its fixation tail inside the bore of the root, the pressure member being in passive position and leaving the sectors of the tail free to retract; the passage of the relief structure of the implant root (or of the tail) is effected by a centripetal retraction of the sectors of the tail by the play of the elasticity of these.

At the end of penetration, the hollow and raised structures of the tail and the root cooperate, conditioning a precise predetermined depth of penetration of the first into the second. In this position, the tail is retained in the implant root but can be angularly positioned appropriately. After adjusting this angular position, it suffices to actuate the operating means so that the pressure member generates the expansion of the tail and its blocking inside the implant root; the suprastructure is then fixed in a precise and resistant manner in the appropriate position, the hollow and relief structures cooperating without the possibility of being released from one another due to the centrifugal blocking of the sectors of the tail.

To remove the infrastructure, it suffices to actuate the operating means in the opposite direction: the sectors of the tail are radially released and the tail can be extracted thanks to the centripetal retraction faculty of said sectors.

 According to a preferred embodiment, the implant root has in its bore a relief structure constituted by an annular rib which projects on its internal surface, while the tail of the suprastructure has externally a hollow structure constituted by a groove formed in the sector level. When the tail is placed in the implant root, the centripetal retraction of the sectors occurs when the end of the tail comes into contact with the rib of the implant root; preferably, the tail of the suprastructure is chamfered at its end along its peripheral border in order to facilitate the retraction of the sectors when the said end is pressed against the rib of the implant root. When removing the tail, centripetal retraction is ensured by the support of the lower flank (located towards the free end) of the groove of the tail against the lower flank of the rib of the implant root; preferably, these sides are frustoconical in order to facilitate centripetal retraction.

 It should be emphasized that the implant root of the implant according to the invention has a cylindrical internal bore whose surface is smooth (with the exception of the abovementioned relief structure). With equal dimensions, such an implant root benefits from mechanical characteristics far superior to those of the known roots which secure the tail by screwing; in fact, the zones of least resistance, incipient fractures, which exist in the known implants between the facing threads are eliminated.

 The implant according to the invention can be of the straight type; the tail and the abutment of the suprastructure then have collinear axes. In this case, the means for operating the suprastructure advantageously comprise a screw which is screwed into a tapped portion of the hollow core of the false stump and which is extended by a rod in the tail of the suprastructure; this rod ends at the converging ramp by a convex end which constitutes the pressure member. Such an embodiment leads to an economical implant, which benefits from all the functional advantages of the invention.

 The implant according to the invention can also be of the angled type; the tail and the abutment of the suprastructure then form between them a predetermined angle, for example 60, 120, 200 or 300. In this case, the means for operating the suprastructure advantageously comprise, on the one hand, a screw screwed into a tapped portion of the hollow core of the abutment, on the other hand, several elements with convex ends, arranged in contact with each other in the hollow core; the screw bears against the first element, while the last element located at the level of the converging ramp has a convex end constituting the pressure member. The elements which are housed at the bent portion of the suprastructure are preferably substantially spherical balls. Such operating means allow, in the case of an angled implant, to ensure in the best conditions, the blocking or the unlocking of the tail sectors and thus benefiting from all the functional advantages of the invention, whatever the value of the angulation of the implant.

The invention extends to a delivery instrument intended to facilitate the positioning of the implant root of the implant defined above. This instrument comprises a barrel, an operating head surmounting said barrel and a tail extending the barrel opposite the head; it is essentially characterized in that
- the barrel, the head and the tail have a hollow core extending over their entire length and provided with a converging ramp at the free end of the tail,
- said tail is provided with slots extending from its free end over a fraction of its length, in order to delimit several sectors,
said tail has externally, at the level of its sectors, a hollow structure (or relief), combined with the structure of the implant root and adapted to cooperate with the latter when the tail is in place in the implant root,
- the tail slits are adapted to allow the sectors to undergo
on the one hand, a radial retraction allowing them to retract in the centripetal direction over a depth at least equal to the thickness of the relief structure of the implant root (or of the tail),
on the other hand, a radial expansion,
- the hollow (or relief) structure of the tail is profiled to ensure the centripetal retraction of its sectors when it is placed in the implant root or when it is removed,
- a screw is screwed into a tapped portion of the hollow core of the head and the barrel, said screw extending, in the tail of the suprastructure, by a rod which ends at the converging ramp by a convex pressure end .

 As will be better understood below, such an instrument is capable of playing the role of means for gripping and retaining the implant root during its anchoring in the bone site in order to facilitate this anchoring.

The invention also extends to a protective element intended to temporarily cover the implant root of the implant defined above; this protective element comprises a tail surmounted by a collar, and is essentially characterized in that
the tail has a hollow core over at least a fraction of its length, said hollow core extending to its free end opposite the collar,
said tail is provided with slots extending from its free end over part of its length, in order to delimit several sectors,
said tail has externally at its sectors, a hollow structure (or relief), combined with the structure of the implant root and adapted to cooperate with the latter when the tail is in place in the implant root,
the tail slits are adapted to allow the sectors to undergo a radial retraction allowing them to retract in the centripetal direction to a depth at least equal to the thickness of the relief structure of the implant root (or of the tail ),
the hollow structure (or relief) of the tail is profiled to ensure the centripetal retraction of its sectors when it is placed in the implant root or when it is removed.

 Thus, during the period of nurse and healing, the internal bore of the implant root is protected by this element which is clipped into it. The collar of said protective element is preferably provided with a tapped hole for the establishment of a cap composed of a head and a short threaded screw. This cap facilitates handling during the healing phase of the soft tissue, and serves as a gauge to define the gingival height.

Other characteristics, objects and advantages of the invention will emerge from the description which follows with reference to the appended drawings, which present, by way of nonlimiting examples, two embodiments of implants in accordance with the invention, and a fitting instrument and a corresponding protection element; on these drawings which form an integral part of the present description
FIGS. 1 a and 1 b are axial sections on an expanded scale representing a straight implant in accordance with the invention, respectively its suprastructure and its implant root,
FIGS. 2a and 2b are cross sections respectively of the suprastructure by a plane AA and of the implant root by a plane BB,
- Figures 3a, 3b, 3c and 3d are schematic sections illustrating the placement of the suprastructure in the implant root,
FIG. 4 is a schematic section showing the implant and its prosthesis in place on a site,
FIG. 5 is an axial section of another embodiment (angled implant) ready to receive its prosthesis,
FIG. 6 is an axial section of a delivery instrument according to the invention, while FIG. 7 illustrates, in axial section, this instrument carrying an implant root,
- Finally Figures 8a, 8b and 8c illustrate in axial section a protective element (Figure 8b) and its cap (Figure 8a) intended to protect an implant root of the aforementioned type (Figure 8c).

 The multiblock dental implant shown by way of example in FIGS. 1-4 (scale of the order of 8) is a straight implant, composed of an implant root 1 (FIGS. 1b, 2b), for example made of titanium, which has a tubular shape whose internal bore 2 is closed by a bottom 3 provided with external recesses 4 intended to prevent rotation of the implant root, once the latter in place. On its external cylindrical face, the implant root is provided with a thread which can be self-tapping, with a view to its anchoring by screwing in the maxillary site.

 The internal bore 2 of the root is provided with an annular rib 6 which projects from its cylindrical surface, this surface being smooth in its other parts. This rib is disposed in the lower half of the root (bottom side 3) and is delimited by a frustoconical lower flank 6b and a frustoconical upper flank 6a, separated by a cylindrical face 6c.

The taper angle ss of the lower flank is greater than the taper angle a of the upper flank; for example, the angle a can be between 100 and 250, and the angle ss between 350 and 55.

 The other part of the implant, called the suprastructure 7 (FIGS. 1a, 2a), is also made of titanium and comprises a false stump 8, a tail 9 and a gingival junction 10 between these elements. The longitudinal axis of the abutment and the gingival junction is collinear with that of the tail. Shoulders such as 10a and 10b limit the gingival junction 10: they are called to correspond respectively with the bone / gum interface and with the external surface of the gum, as illustrated in FIG. 4.

 The suprastructure 7 is pierced right through along its longitudinal axis, with a hollow core 11 of circular section. At the free end of the tail 9, this hollow core comprises a converging ramp 12 of frustoconical shape, the angle at the top of which is in particular between 500 and 700, in the example of the order of 600.

In addition, the hollow core 11 is tapped over a portion 13 of its length which extends to the free end of its false stump, so as to allow the screwing of a screw.

 The tail 9 of the suprastructure has an external diameter slightly smaller than that of the bore 2 of the implant root so as to be able to lodge with gentle friction therein. Said tail 9 is separated over a fraction of its length into several sectors such as 9a, by longitudinal slots 14 (in the example four in number) which start from the free end of the tail. Thus, this tail part can undergo a retraction or a radial expansion by the play of the elasticity of the sectors 9a. It should be noted that the hollow core of the tail 9 is of cylindrical shape with a smooth surface and has only the aforementioned slots 14 and the converging ramp 12 at its end.

 The suprastructure 7 contains a screw 15 screwed into the tapped portion 13 of its hollow core this screw is extended by a cylindrical rod 16 which extends along the tail and ends at the converging ramp 12 by a convex end 17, in the hemispherical example. The screw 15 provided with a hollow imprint 15a acts as an operating means making it possible to move the end 17 longitudinally (which acts as a pressure member) with a view to placing it under pressure against the converging ramp 12 and block it in this position (active position) or, on the contrary, move it away from said ramp 12 (passive position: Figure la). In the active position, the pressure end 17 tends to spread the sectors 9a of the tail, while, in the passive position, it leaves them free to play by the play of their radial elasticity.

 In addition, the tail 9 has externally at its sectors 9a, a groove 18 of shape combined with that of the annular rib 6 of the implant root. This groove is longitudinally positioned so as to correspond with said rib when the tail is in place in the implant root.

In this situation, the groove 18 is shaped to contain the rib 6; for this purpose, it is delimited by a lower frusto-conical flank 18b with a taper angle 3 of between 350 and 550 and an upper frusto-conical flank 18a with a taper angle a between 100 and 250, separated by a cylindrical surface 18c (back of the throat). The dimensions of the groove 18 correspond to the clearance close to those of the rib 6.

 In addition, the tail 9 of the suprastructure is chamfered at its end on its peripheral edge 9b.

 After anchoring the implant root 1 in the bony site of the maxilla, the practitioner introduces the tail 9 of the suprastructure into the bore of said root, as illustrated in FIG. 3a. The rod 16 and the pressure end 17 are in the passive position and leave the sectors 9a of the tail free to play radially. In the idle state, the longitudinal slots 14 which delimit the sectors have a width greater than approximately one and a half times the thickness of the annular rib 6 of the root, so that the sectors can undergo a radial retraction in the direction centripetal over a depth at least equal to the thickness of the rib 6. For example, it is possible to provide slots 14 of width equal to approximately 1.8 e, where e is the thickness of the rib 6.

 Thus, as illustrated in FIGS. 3a and 3b, during the penetration of the tail 9 into the implant root, the chamfered end 9b of the tail bears against the frustoconical flank 6a of the rib 6 and causes a radial retraction of the sectors 9a, which retract, allowing the sinking of the tail to continue. The rod 16 and its pressure end 17 in the passive position have no contact with the tail and leave the sectors of the latter free to retract.

 At the end of penetration (Figure 3c), the sectors return to their natural position by the play of their elasticity: the groove 18 of the tail contains the rib 6 of the root.

 To block the tail in the root, the practitioner operates the screw 15 by means of an Allen key in order to pressurize the hemispherical end 17 against the converging ramp 12. In this state, the rib 6 and the groove 18 are locked one inside the other extremely efficiently, without the possibility of relative movement. This gives an extremely resistant fixation of the suprastructure with respect to the implant root.

 The suprastructure can be easily removed from the root if necessary. It suffices to maneuver the screw 15 in the opposite direction to move the pressure end 17 upwards and release the sectors 9a.

The tail can then be extracted by an axial pull which generates the centripetal retraction of the sectors (retraction facilitated by the frustoconical shape of the lower flanks of the groove and of the rib). The taper angle of these sides allows, in conjunction with the elasticity module of the sectors 9a, to adjust the traction force necessary to remove the tail after unlocking the sectors: these provisions give the tail a stable position, even after unlocking, which facilitates the work of the practitioner.

 Figure 4 shows the implant installed on the site with its prosthesis 19, which is fixed to the abutment 8 by any means. In the example shown, this prosthesis is made of ceramic and has a metallic internal cap 19a which is glued to the abutment. Of course, the false stump of the implant according to the invention can be adapted to allow any other type of fixation of the prosthesis, for example fixing by screwing (by means of combined threading and tapping provided on the false stump and the prosthesis, or by clipping).

 FIG. 5 illustrates the case of an angulated implant in which the axis of the tail of the suprastructure makes a predetermined angle with the axis of the false stump and the gingival junction. The implant root is identical to that already described. The suprastructure has characteristics identical to those already described (slits, groove, converging ramp of the tail ...) with the exception of the differences described below.

 In the angled embodiment presented in FIG. 5, the maneuvering screw 20 is of reduced length and has a hemispherical end 21 which comes to bear with the first ball of a row of spherical balls 22, 23 (in the example two in number) located at the bent portion of the suprastructure. These balls are themselves in abutment against elements with hemispherical ends 24, 25 (in the example two in number). Each element 24, 25 is in the example formed by a cylindrical body having two hemispherical ends.

The last element 25 acts as a pressure member and its hemispherical end is situated at the level of the converging ramp of the tail in order to be able to exert pressure thereon. Such arrangements condition an operation similar to that already described and make it possible to provide any angulation between tail and false stump.

 The implant according to the invention described above (straight or angled) lends itself to easy positioning by means of a positioning instrument as illustrated in FIG. 6. This instrument provides a grip of the implant root to achieve the installation thereof by screwing.

 To this end, the targeted instrument comprises an operating head 26, in particular square, which can be turned by means of a key, a barrel 27 of suitable length and a tail 28 extending the barrel opposite the head. . An assortment of instruments with different barrel lengths can be provided to suit all practical cases.

 The tail 28 is identical to the tail 9 of the suprastructure (FIG. 1a): it has the same structures (slots, groove, converging ramp, chamfer, etc.) and is thus able to penetrate an implant root as illustrated in Figure 7, to be snapped on, fixed and locked.

 To operate this fixing and this locking, a screw 29 is screwed into a threaded portion 30 formed in the hollow core of the head 26 and of a part of the barrel 27. This screw is extended by a rod 31 which extends to the interior of the bole and the tail, and ends at the level of the converging ramp of the tail, by a hemispherical pressure end. In the example, the screw 29 has an external operating head 29a, the rotation of which allows extremely strong locking of the tail 28 in the implant root to be placed. After installation, the unlocking is carried out by a reverse rotation of the screw 29 and the instrument can be removed.

 Figures 8a and 8b show a protective element to temporarily cover an implant root after its installation (illustrated in Figure 8c). This element will protect the internal bore of the root during the nurse period during which the healing of the soft tissues around the root (the establishment of the suprastructure is performed after this period).

 The protective element comprises a tail 32 surmounted by a collar 33 which is provided with a tapped hole 34 for the purpose of installing a cap composed of a head 35 and a short threaded rod 36; the head 35 is provided with an imprint 35a.

 The tail 32 of the protective element is identical to the tail 9 of the suprastructure. However, its maintenance is carried out by simple clipping into the implant root and it is not equipped with internal operating means and pressure member; the hollow core of said tail opens only at its lower free end.

 This protective element is put in place without an instrument by simply pressing in and clipping into the implant root. It can be removed by exerting an axial pull on the head 35. The head 35 facilitates handling and serves as a gauge for defining the gingival height. An assortment of several caps with heads of different heights can be provided to suit all practical cases.

Claims (13)

 1 / - Multi-block dental implant, for the establishment and maintenance of a prosthesis on a bone site, comprising, on the one hand, a suprastructure (7) provided with a false stump (8) prosthesis support and a tail (9) for its attachment, on the other hand, an implant root (1) adapted to be anchored in the bone site and provided with an internal bore (2) to receive the tail of the suprastructure, in which  (a) the suprastructure (7) is provided with a hollow core (11) extending over its entire length, said hollow core opening at the free end of the abutment (8) and being provided with a converging ramp ( 12) at the free end of the tail (9),  (b) said tail (9) is provided with slots (14) extending from its free end over a fraction of its length, in order to delimit several sectors (9a),  (c) said tail (9) contains a mechanical pressure member (17), movable between an active position where this member exerts pressure on the converging ramp (12) tending to spread the sectors (9a) and a passive position where said sectors remain free,  (d) operating means (15, 16) are associated with the pressure member (17) in order to allow said member to be displaced longitudinally towards its active position and to block it under pressure against the converging ramp (12), said dental implant being characterized in that  (e) the implant root (1) has in its internal bore a relief -or hollow-structure (6) longitudinally positioned to be located at the level of the sectors (9a) of the tail (9) of the suprastructure when the latter is in place in the implant root,  (f) said tail (9) of the superstructure has, externally at its sectors (9a), a hollow-or relief-structure (18), combined with the structure (6) of the implant root and adapted to cooperate with this last when the tail is in place in the implant root,  (g) the slots (14) of the tail are adapted to allow the sectors (9a) to undergo  on the one hand, in the passive position of the pressure member (17), a radial retraction allowing them to retract in the centripetal direction over a depth at least equal to the thickness of the relief structure (6) the implant root (or tail),  on the other hand, a radial expansion, in the active position of the pressure member (17),  (h) the combined hollow and raised structures (18, 6) of the tail and of the implant root are profiled to ensure the centripetal retraction of the sectors (9a) during the positioning of the tail in the implant root or during its removal, the pressure member being in the passive position.  2 / - dental implant according to claim 1, characterized in that  the implant root (1) has in its bore (2) a relief structure constituted by an annular rib (6) projecting from its internal surface,  the tail (9) of the suprastructure has externally a hollow structure constituted by a groove (18) formed at the level of the sectors (9a).  3 / - dental implant according to claim 2, characterized in that  the rib (6) and groove (18) of the root and the tail each have two frustoconical sides (6a, 6b; 18a, 18b) separated by a cylindrical face (6c, 18c),  the so-called lower flanks (6b, 18b) situated towards the free end have a taper angle B of between 350 and 550, while the other so-called upper flanks (6a, 18a) have a taper angle of between 10 and 250 ,  the tail (9) is chamfered at its end on its peripheral edge (9b).  4 / - dental implant according to one of claims 2 or 3, characterized in that the tail (9) is provided with slots (14) of width greater than about one and a half times the thickness of the annular rib (6) .  5 / - dental implant according to one of the preceding claims, wherein the converging ramp (12) of the tail is a tapered ramp with an angle at the apex between SO0 and 700  6 / - dental implant according to one of the preceding claims, in which  . the implant root (1) has a cylindrical internal bore with a smooth surface, having only the abovementioned structure (6) in relief (or hollow),  . the tail (9) of the suprastructure is provided with a hollow core of cylindrical shape with smooth surface, presenting only the aforementioned slots (14) and the converging ramp (12) at its end.  7 / - dental implant according to one of the preceding claims, wherein the implant root (1) is provided with an external thread (5) to be screwed into the bone site.  8 / - dental implant according to one of claims 1 to 7, straight type, wherein the tail and the abutment of the suprastructure have collinear axes, characterized in that the means for operating the suprastructure include a screw (15) screwed into a tapped portion (13) of the hollow core of the abutment, said screw extending by a rod (16) in the tail of the suprastructure, said rod ending at the level of the converging ramp (12) by a convex end (17) constituting the pressure member.  9 / - dental implant according to one of claims 1 to 7, of angled type, wherein the tail and the abutment of the suprastructure form between them a predetermined angle, characterized in that the means for operating the suprastructure include on the one hand, a screw (20) screwed into a tapped portion of the hollow core of the abutment, on the other hand, several elements with convex ends (22-25), arranged in contact with each other in the hollow core, the screw bearing against the first element (22), while the last element (25) located at the level of the converging ramp has a convex end constituting the pressure member.  10 / - dental implant according to claim 9, characterized in that the elements with convex ends disposed at the bent portion of the suprastructure are substantially spherical balls (22, 23).  11 / - Positioning instrument to facilitate the establishment of an implant root of an implant according to one of claims 1 to 10, comprising a barrel (27), an operating head (26) surmounting said barrel, and a tail (28) extending the barrel opposite the head, characterized in that  - the bole, the head and the tail have a hollow core extending over their entire length and provided with a converging ramp at the free end of the tail,  - said tail is provided with slots extending from its free end over a fraction of its length, in order to delimit several sectors,  said tail has externally, at the level of its sectors, a hollow structure (or relief), combined with the structure of the implant root and adapted to cooperate with the latter when the tail is in place in the implant root,  - the tail slits are adapted to allow the sectors to undergo  on the one hand, a radial retraction allowing them to retract in the centripetal direction over a depth at least equal to the thickness of the relief structure of the implant root (or of the tail),  on the other hand, a radial expansion,  - the hollow (or relief) structure of the tail is profiled to ensure the centripetal retraction of its sectors when it is placed in the implant root or when it is removed,  a screw is screwed into a tapped portion of the hollow core of the head and of the barrel, said screw extending by a rod in the tail of the suprastructure, said rod ending at the level of the converging ramp by a convex pressure end .  12 / - Protective element for temporarily covering an implant root of an implant according to one of claims 1 to 10, comprising a tail (32) surmounted by a collar (33), characterized in that  . the tail has a hollow core over at least part of its length, said hollow core extending to its free end opposite the collar,  . said tail is provided with slots extending from its free end over a fraction of its length, in order to delimit several sectors,  . said tail externally comprises at its sectors, a hollow structure (or relief), combined with the structure of the implant root and adapted to cooperate with the latter when the tail is in place in the implant root,  the tail slits are adapted to allow the sectors to undergo a radial retraction allowing them to retract in the centripetal direction to a depth at least equal to the thickness of the relief structure of the implant root (or of the tail ),  . the hollow structure (or relief) of the tail is profiled to ensure the centripetal retraction of its sectors when it is placed in the implant root or when it is removed.  13 / - protective element according to claim 12, characterized in that the collar (33) is provided with a tapped hole (34) for the establishment of a cap composed of a head (35) and a short threaded rod (36).