Abstract:
Assembly comprising a component and a one-piece axial limit stop device ( 1 ) intended to be placed in a bore of said component in order to retain an element therein, comprising an annular ring ( 2 ) with symmetry of revolution about a central axis (I-I), and comprising at least one angular portion ( 3, 4 ) rigidly connected to the annular ring ( 2 ), developing in an arc between a first end ( 3   a,    4   a ), joined to the distal end ( 2   b ) of the annular ring ( 2 ), and a second, free end ( 3   b,    4   b ). The angular portion ( 3, 4 ) is in part movable from its first end ( 3   a,    4   a ), in a transverse plane perpendicular to the central axis (I-I), between a retracted position and at least one protruding position, being elastically returned permanently to the protruding position. In the retracted position, the angular portion ( 3, 4 ) is included within the volume of a cylinder continuing the outer cylindrical surface of the annular ring ( 2 ). In the protruding position, the free end ( 3   b,    4   b ) of the angular portion ( 3, 4 ) extends radially beyond the volume of the cylinder continuing the outer cylindrical surface of the annular ring ( 2 ). The component bore has a specific inner geometry allowing the axial limit stop device ( 1 ) to be easily attached and reliably fixed, while at the same time allowing easy detachment and extraction of the axial limit stop device ( 1 ) in order to permit the removal of the element in the event of the latter sustaining damage.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention relates to an assembly comprising a component and an axial limit stop device intended to be placed in a bore of said component in order to retain an element therein. The field of use of the invention is in particular the field of dentistry, the aim being to retain a transfixing screw in a bore of a dental prosthesis that is intended to be attached to a dental implant. 
         [0002]    The document EP 0 801 544 discloses a dental abutment intended to be attached to and fixed on a dental implant, which is itself intended to be inserted into the maxillary or mandibular bone of a patient. The dental abutment subsequently receives a final dental prosthesis made of ceramic or metal. The dental abutment has a continuous bore in which an axial limit stop device is arranged, which is intended to ensure the axial retention of a screw held captive in the bore of the abutment. The threaded shank portion of the screw is intended to be received by screwing in an internally threaded bore of the dental implant. The dental abutment is fixed to the dental implant by fixing means (specifically a screw) passing through the dental abutment, hence the expression “transfixed dental abutment”, and more generally “transfixed component”. The axial limit stop device has a radially slit ring, which simultaneously engages under the screw head and in an annular groove formed in the bore extending through the abutment. 
         [0003]    In the event of an excessive screwing torque being imparted to the screw, the latter may sustain damage, especially by breaking in the area of its shank. It is then desirable to remove what remains of the screw in the continuous bore of the abutment, in order to be able to insert a new screw there. However, the slit ring of document EP 0 801 544 is unfortunately very difficult or even impossible to remove, mainly on account of the very small dimensions of the components in question (dental abutment and slit ring). Thus, any damage to the screw renders the dental abutment unusable. The practitioner is then compelled to use a new dental abutment provided with an intact screw. 
         [0004]    Resorting to a new dental abutment is not in itself a great inconvenience, since it is a component of which the shape is not adapted to each patient and of which the practitioner has several models. A standard and rapid exchange is thus possible. 
         [0005]    For many years, it has been sought to limit the number of components by managing without dental abutments for attaching and fixing a final dental prosthesis to a dental implant inserted in the maxillary or mandibular bone of a patient. To do so, it has been proposed to insert the screw directly into a bore formed in the final dental prosthesis. The fixing screw can be driven in rotation by means of a screwing tool which accesses the screw head by way of an access well that communicates with the bore (in most cases obliquely intersecting the bore) in which the screw is retained. These dental prostheses are often called “transfixed dental prostheses” since the screwing tool and the screw pass right through them when they are being fixed. However, in the event of damage to the screw, in the same way as has been described above for the dental abutment, it is likewise impossible for what remains of the screw to be removed from the bore. The damage to the screw thus renders the final prosthesis unusable. However, the outer shape of the final prosthesis is configured uniquely for each patient, by a process that is often lengthy and difficult. The practitioner is then compelled to manufacture a new final dental prosthesis, which takes a lot of time and is expensive. 
         [0006]    This problem is even more critical in the case of transfixed multiple dental prostheses that are intended to be received on a plurality of dental implants and, for this purpose, have a plurality of captive screws: damage to one of the screws can render the whole prosthesis unusable. 
         [0007]    The document WO 2012/037014 A2 describes an annular ring with symmetry of revolution about a central axis, comprising two angular arc portions with respective free ends which are radially movable, in a transverse plane perpendicular to the central axis, between a retracted position and at least one protruding position, being elastically returned permanently to the protruding position. This annular ring is used to form a ratchet-type locking nut being placed in the bore of a washer. When the annular ring is received in the bore of the washer, optional tongues attached by welding allow the assembled annular ring to be retained definitively in the washer. To do so, the tongues bear permanently under the annular ring and oppose any removal of the ring from the washer by translation, and they do this irrespective of the rotation position of the annular ring with respect to the washer. 
         [0008]    The document EP 1 060 716 A2 describes an axially compressible locking nut used in an orthopedic implant in the form of a prosthetic femoral stem. 
       SUMMARY OF THE INVENTION 
       [0009]    A problem addressed by the present invention is to make available an assembly comprising a component and an axial limit stop device intended to be placed in a bore of said component in order to reliably retain an element therein, but with the axial limit stop device being able to be detached easily in order to permit the removal of the element in the event of the latter sustaining damage. 
         [0010]    According to another aspect, the present invention aims to make available an assembly comprising a component and an axial limit stop device intended to be mounted removably in a bore of said component, said component having very small dimensions, as in the case of a dental prosthesis in particular. 
         [0011]    To achieve these objects and others, the invention proposes an assembly according to claim  1 . 
         [0012]    When said at least one angular portion of the axial limit stop device is in the retracted position, the axial limit stop device can be inserted by a simple movement of axial translation, along the first longitudinal axis and in the direction of the distal end of the component bore, into the first portion of the component bore. Then, by driving the axial limit stop device a little farther into the component bore in the direction of the distal end of the component bore, said at least one angular portion can penetrate into the second component bore portion and come into line with the retaining seat of the second component bore portion and engage there in the protruding position by elastic return. If an attempt is made to extract the axial limit stop device from the bore, by an axial translation movement along the first longitudinal axis and in the direction of the inlet orifice of the component bore, said at least one angular portion comes to bear against the proximal retaining face of the retaining seat and opposes this extraction. The axial limit stop device is thus able to hold an element (such as a screw and screw head) captive in the bore. 
         [0013]    In the case where the element retained in the bore is damaged and must be withdrawn from the component, it is still possible to extract the axial limit stop device from the bore despite everything. To do so, the axial limit stop device is turned about the first longitudinal axis of the bore in such a way as to bring said at least one angular portion against the angular part of the lateral surface of the second component bore portion, which extends in the continuation of the cylindrical lateral surface of the first component bore portion. Said at least one angular portion is thus brought back to the retracted position, such that the axial limit stop device can then be extracted from the component bore, via the first component bore portion, by a simple movement of axial translation along the first longitudinal axis and in the direction of the inlet orifice of the component bore. 
         [0014]    Advantageously, said at least one angular portion can be kept apart from the distal end of the annular ring, along the central axis, by a spacer extending parallel to the central axis. The elastic return of the angular portion to the protruding position is therefore not disturbed by the angular portion rubbing against the distal end of the annular ring. 
         [0015]    Preferably, perpendicular to the central axis, said at least one angular portion can have a thickness that decreases from its first end toward its second free end. This effectively limits the stresses induced in the area of connection between the spacer and the angular portion by a flexion of the angular portion bringing the latter back to the retracted position. If these stresses were too high, they could end up breaking the arm and/or the angular portion near their connection, especially in the case of an axial limit stop device of small dimensions. 
         [0016]    An indentation, allowing the annular ring to be driven in rotation about the central axis, can advantageously be formed in a proximal end face of the annular ring. The proximal end of the annular ring is in fact the part of the axial limit stop device that is most easily accessible from outside of the component. 
         [0017]    Preferably, the indentation can comprise two diametrically opposite notches. An indentation having symmetry makes it possible to more easily turn the axial limit stop device about its central axis. 
         [0018]    Advantageously, the axial limit stop device can have two angular portions movable in the same transverse plane. 
         [0019]    In the case of a plurality of angular portions, provision can preferably be made that: 
         [0020]    the second component bore portion has a plurality of retaining seats, 
         [0021]    each retaining seat is separated from the adjacent retaining seat by an angular part of the lateral surface of the second component bore portion which extends in the continuation of the cylindrical lateral surface of the first component bore portion. 
         [0022]    Having two or more angular portions engaged in respective retaining seats makes it possible to better retain the axial limit stop device axially in the component. 
         [0023]    The angular parts of the lateral surface of the second component bore portion, which extend in the continuation of the cylindrical lateral surface of the first component bore portion and which separate the adjacent retaining seats, allow all of the angular portions to be brought back simultaneously to the retracted position when the axial limit stop device is driven in rotation about the central axis. 
         [0024]    The element intended to be placed in the bore of the component with the aid of the axial limit stop device can advantageously have: 
         [0025]    a proximal portion of the element having a cross section with dimensions less than or equal to the internal diameter of the annular ring, 
         [0026]    a distal portion with a cross section having at least one dimension greater than the internal diameter of the annular ring but less than or equal to the diameter of the first component bore portion, 
         [0027]    a shoulder connecting the proximal portion and distal portion of the element. 
         [0028]    The proximal portion of the element can thus pass through the axial limit stop device in order to protrude from the bore of the component, while the distal portion of the element bears axially along the shoulder against the axial limit stop device, in order to be retained in the bore of the component. 
         [0029]    Preferably, the element intended to be placed in the cylindrical bore of the component can be a screw, of which the head constitutes the distal portion of the element and of which the threaded shank constitutes the proximal portion of the element. 
         [0030]    To make it easier for the assembly according to the invention to be put together by inserting the axial limit stop device into the bore of the component, it is possible to use a mounting tool in which the following provisions can be made: 
         [0031]    a tubular sleeve with a central bore extends along a second longitudinal axis between a distal orifice and a proximal orifice, 
         [0032]    the central bore of the tubular sleeve has a tubular sleeve distal bore portion, extending from the distal orifice, a tubular sleeve intermediate bore portion, following on from the tubular sleeve distal bore portion and extending toward the proximal orifice, and a tubular sleeve proximal bore portion following on from the tubular sleeve intermediate bore portion and extending as far as the proximal orifice, 
         [0033]    the tubular sleeve intermediate bore portion has a circular cross section with a diameter equal to or slightly greater than the external diameter of the annular ring, 
         [0034]    the tubular sleeve distal bore portion has at least one retaining seat which extends radially with respect to the second longitudinal axis out from the volume of the cylinder continuing the cylindrical surface of the tubular sleeve intermediate bore portion, said retaining seat being able to receive said at least one angular portion of the axial limit stop device in the protruding position, 
         [0035]    the retaining seat has a proximal retaining face extending along a transverse plane substantially perpendicular to the second longitudinal axis and connecting to the cylindrical lateral wall of the tubular sleeve intermediate bore portion, 
         [0036]    the tubular sleeve distal bore portion has at least one angular part with a lateral surface extending in the continuation of the cylindrical lateral surface of the tubular sleeve intermediate bore portion. 
         [0037]    A mounting tool of this kind proves particularly useful when the axial limit stop device has very small dimensions, as is especially the case when it is used to retain an element such as a screw in a dental prosthesis. 
         [0038]    To insert the axial limit stop device into the bore of the component, it is first of all inserted into the tubular sleeve distal bore portion. Said at least one angular portion, then in the protruding position, is engaged in said at least one retaining seat provided in the tubular sleeve distal bore portion. By turning the axial limit stop device about the central axis, said at least one angular portion is then brought into line with said at least one angular part of the lateral surface extending in the continuation of the cylindrical lateral surface of the tubular sleeve proximal bore portion. The angular portion is thus brought back to the retracted position. The distal orifice of the tubular sleeve is then brought in immediate proximity to the inlet orifice of the component bore. The axial limit stop device, with its angular portion in the retracted position, is then pushed out of the tubular sleeve distal bore portion in order to be engaged in the first component bore portion until the angular portion of the axial limit stop device penetrates into the second component bore portion and comes into line with the retaining seat of the second component bore portion in order to engage there in the protruding position by elastic return. 
         [0039]    To push the axial limit stop device out of the tubular sleeve distal bore portion, a longitudinal shaft can be passed through the tubular sleeve from the direction of the proximal orifice thereof. 
         [0040]    The element intended to be retained in the component bore can be first engaged in the component bore before the axial limit stop device is engaged there. Alternatively, the element intended to be retained in the component bore can be introduced into the component bore at the same time as the axial limit stop device. 
         [0041]    Preferably, provision can be made that: 
         [0042]    the mounting tool has a longitudinal shaft extending along a third longitudinal axis, with a distal portion having an outer circular cross section of diameter substantially equal to the diameter of the tubular sleeve intermediate bore portion, 
         [0043]    the distal portion of the longitudinal shaft extends along the third longitudinal axis by a length greater than the sum of the lengths of the tubular sleeve intermediate bore portion and tubular sleeve distal bore portion along the second longitudinal axis, 
         [0044]    the distal portion of the longitudinal shaft has, at a free end, a distal face intended to bear against the proximal end of the annular ring, 
         [0045]    the distal face of the distal portion of the longitudinal shaft has raised areas able to cooperate with the indentation formed in the face of the proximal end of the annular ring in order to drive the annular ring in rotation about its central axis. 
         [0046]    The longitudinal shaft thus serves simultaneously: 
         [0047]    to push the axial limit stop device out of the tubular sleeve distal bore portion in order to engage the axial limit stop device in the first component bore portion, 
         [0048]    to turn the axial limit stop device about the central axis in the tubular sleeve distal bore portion in order to bring the angular portion to the retracted position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]    Other subjects, features and advantages of the present invention will become clear from the following description of particular embodiments, with reference being made to the attached figures in which: 
           [0050]      FIG. 1  is a perspective view of an example of an axial limit stop device intended to be used in a particular embodiment of the assembly according to the invention; 
           [0051]      FIG. 2  is another perspective view of the axial limit stop device of  FIG. 1 , seen in a different direction from that of  FIG. 1 ; 
           [0052]      FIG. 3  is a bottom view of the axial limit stop device of  FIG. 1 ; 
           [0053]      FIG. 4  is a top view of the axial limit stop device of  FIG. 1 ; 
           [0054]      FIG. 5  is a bottom view, in cross section, of the axial limit stop device of  FIG. 1 ; 
           [0055]      FIG. 6  is a perspective view of a component in the form of a transfixed multiple dental prosthesis, supported by a plurality of dental implants; 
           [0056]      FIG. 7  is a top view of the transfixed multiple dental prosthesis of  FIG. 6 ; 
           [0057]      FIG. 8  is a detailed cross-sectional view, on a section plane A-A, of a particular embodiment of the assembly according to the invention, comprising the component from  FIG. 6 , in the form of a transfixed multiple dental prosthesis, in a bore of which an element is retained by the axial limit stop device of  FIG. 1 ; 
           [0058]      FIG. 9  is another detailed cross-sectional view of the assembly from  FIG. 8 , on a first variant of a dental implant, seen in a section plane B-B perpendicular to the section plane A-A of  FIG. 8 ; 
           [0059]      FIG. 10  is a detailed cross-sectional view of the bore of the component from  FIG. 6 , in the form of a transfixed multiple dental prosthesis, seen in a section plane C-C perpendicular to the section planes A-A and B-B of  FIGS. 8 and 9 ; 
           [0060]      FIG. 11  is a cross-sectional side view of the element retained in the bore of the component, in the form of a transfixed multiple dental prosthesis, from  FIGS. 8 and 9 ; 
           [0061]      FIG. 12  is a side view of the element from  FIG. 11 ; 
           [0062]      FIG. 13  is a perspective view of the element from  FIG. 11 ; 
           [0063]      FIG. 14  is a cross-sectional view of a tubular sleeve of a mounting tool; 
           [0064]      FIG. 15  is a view of the distal end of the tubular sleeve from  FIG. 14 ; 
           [0065]      FIG. 16  is a side view of the tubular sleeve from  FIG. 14 , of an axial limit stop device from  FIG. 1 , and of a longitudinal shaft of the mounting tool; 
           [0066]      FIG. 17  is another side view of the elements of  FIG. 16 , seen in a direction perpendicular to that of  FIG. 16 ; 
           [0067]      FIGS. 18 and 19  are detailed cross-sectional side views illustrating the cooperation of the elements of  FIG. 16 ; 
           [0068]      FIGS. 20 and 21  are perspective views illustrating the use of the tubular sleeve from  FIG. 14  and of the longitudinal shaft from  FIG. 16  for fitting an axial limit stop device from  FIG. 1  in a bore of the component from  FIG. 6 , in the form of a transfixed multiple dental prosthesis; and 
           [0069]      FIG. 22  is another detailed cross-sectional view of the assembly from  FIG. 8 , on a second variant of a dental implant, seen in a section plane B-B perpendicular to the section plane A-A of  FIG. 8 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0070]      FIGS. 1 to 5  depict an example of an axial limit stop device  1  intended for the manufacture of a particular embodiment of an assembly  100  according to the invention (said assembly  100  can be seen more particularly in  FIGS. 8, 9 and 22 ). The axial limit stop device  1  is in one piece and comprises an annular ring  2  which has symmetry of revolution about a central axis I-I and which extends along the central axis I-I between a proximal end  2   a  and a distal end  2   b . Two angular portions  3  and  4  develop in an arc between first ends  3   a  and  4   a , connected to the distal end  2   b  of the annular ring  2 , and a second free end  3   b  and  4   b . The angular portions  3  and  4  are in part radially movable by deformation, starting from their first ends  3   a  and  4   a , in one and the same transverse plane P 1  perpendicular to the central axis I-I, between a retracted position (illustrated in broken lines in  FIG. 4 ) and at least one protruding position (illustrated in solid lines in  FIGS. 1 to 5 ), by being elastically returned permanently to the protruding position. 
         [0071]    As is illustrated in  FIG. 4  in broken lines, in the retracted position, the angular portions  3  and  4  are included within the volume of a cylinder C 1  continuing the outer cylindrical surface of the annular ring  2 . In the protruding position, the free ends  3   b  and  4   b  of the angular portions  3  and  4  protrude beyond the volume of the cylinder C 1  continuing the outer cylindrical surface of the annular ring  2 . 
         [0072]    It will be seen more particularly in  FIGS. 1 and 2  that the first ends  3   a  and  4   a  of the angular portions  3  and  4  and the distal end  2   b  of the annular ring  2  are connected by spacers  5  and  6  extending parallel to the central axis I-I. The angular portions  3  and  4  are thus kept apart from the distal end  2   b  of the annular ring  2  along the central axis I-I. 
         [0073]    It will be seen more particularly in  FIG. 5  that, perpendicular to the central axis I-I, the angular portions  3  and  4  have a thickness which decreases from the first ends  3   a  and  4   a  toward the second free ends  3   b  and  4   b . More precisely, the angular portions  3  and  4  have, near their first ends  3   a  and  4   a , a radial thickness e 1  that is greater than the radial thickness e 2  near their second free ends  3   b  and  4   b . The thickness of the angular portions  3  and  4  decreases progressively from e 1  to e 2 . 
         [0074]    It will be seen more particularly in  FIGS. 1 to 3  that the axial limit stop device  1  comprises an indentation  7  for driving in rotation, allowing the annular ring  2  to be driven in rotation about the central axis I-I. This indentation  7  is formed in a face  8  of the proximal end  2   a  of the annular ring  2 . In more detail, the indentation  7  has two diametrically opposite notches  9  and  10 . 
         [0075]    The axial limit stop device  1  in  FIGS. 1 to 5  is intended to be placed in the bore of a component  11  in order to retain an element  14  therein. 
         [0076]    In the field of dentistry, the axial limit stop device  1  is intended to be placed in a bore  17  formed in a component in the shape of a dental prosthesis  11 , such as the transfixed multiple dental prosthesis  11  illustrated in  FIGS. 6 and 7 , in order to retain therein a screw  14  such as the one illustrated in  FIGS. 11 to 13 . The transfixed multiple dental prosthesis  11  extends in a plane C-C along a curved prosthetic corridor CP. 
         [0077]    The transfixed multiple dental prosthesis  11  illustrated in  FIGS. 6 and 7  is intended to be attached to and fixed on two dental implants  12  and  13 , which are themselves intended to be received in the maxillary or mandibular bone of a patient. To do this, the transfixed multiple dental prosthesis  11  is fixed on the implants  12  and  13  by way of screws  14  such as those illustrated in  FIGS. 11 to 13 . The screws  14  are accessible by a screwing tool via access wells  15  and  16  which communicate with bores formed in the transfixed multiple dental prosthesis  11 . This is revealed more particularly by  FIGS. 8 and 9 , which are cross-sectional views seen, respectively, along the section planes A-A and B-B illustrated in  FIG. 7 . 
         [0078]    In  FIGS. 8 and 9 , it will be seen that the transfixed multiple dental prosthesis  11  has a bore  17  extending along a first longitudinal axis II-II between a proximal end  17   a , with inlet orifice  18 , and a distal end  17   b . The axial limit stop device  1  is received in the component bore  17  with its central axis I-I coaxial with the first longitudinal axis II-II. The axial limit stop device  1  and the component  11 , which is here in the form of a transfixed multiple dental prosthesis, form an assembly  100 . 
         [0079]    Said component bore  17  has a first component bore portion T 171  extending from the inlet orifice  18  of the component bore  17 , and a second component bore portion T 172  following on from the first component bore portion T 171  and extending toward the distal end  17   b  of the component bore  17 . The component bore  17  additionally has a third component bore T 173  following on from the second component bore portion T 172  and extending as far as the distal end  17   b  of the component bore  17 . 
         [0080]    The first component bore portion T 171  has a circular cross section with a diameter D 1  equal to or slightly greater than the external diameter D 2  of the annular ring  2 . 
         [0081]    The second component bore portion T 172  has two retaining seats  19  and  20  which extend radially with respect to the first longitudinal axis II-II out from the volume of the cylinder C 2  continuing the cylindrical surface of the first component bore portion T 171 . The retaining seats  19  and  20  are able to receive the angular portions  3  and  4  of the axial limit stop device  1  in the protruding position. The shape of the retaining seats  19  and  20  can be seen more particularly in  FIG. 10 , which is a cross-sectional view along the section plane C-C in  FIG. 8 . 
         [0082]    In  FIGS. 8 and 10 , it will be seen that the retaining seats  19  and  20  have proximal retaining faces  21  and  22  extending along a transverse plane P 2  substantially perpendicular to the first longitudinal axis II-II. In other words, the proximal retaining faces  21  and  22  extend in the transverse plane P 2  substantially parallel to the section plane C-C illustrated in  FIG. 8 . The proximal retaining faces  21  and  22  are connected to the cylindrical lateral wall T 171   a  of the first component bore portion T 171 . 
         [0083]    The second component bore portion T 172  has two angular parts  23  and  24  of the lateral surface T 172   a  extending in the continuation of the cylindrical lateral surface T 171   a  of the first component bore portion T 171 . The angular parts  23  and  24  are included within the diametric lines indicated by broken lines in  FIG. 10 . The angular parts  23  and  24  separate the adjacent retaining seats  19  and  20 . 
         [0084]    The retaining seats  19  and  20  develop radially with respect to the first longitudinal axis II-II and substantially along the prosthetic corridor CP. There is therefore more space available radially for drilling the retaining seats  19  and  20  and thereby increasing the axial retention of the axial limit stop device  1 . 
         [0085]    An element intended to be placed in the bore  17  of the component (transfixed multiple dental prosthesis  11 ) is illustrated more particularly in  FIGS. 11 to 13 . This element is a screw  14 , and therefore it will be referred to below synonymously as element  14  or screw  14 . The element  14  has: 
         [0086]    a proximal portion  25  with a cross section having dimensions less than or equal to the internal diameter D 3  of the annular ring  2 , 
         [0087]    a distal portion  26  with a cross section having at least one dimension greater than the internal diameter D 3  of the annular ring  2  but less than or equal to the diameter D 1  of the first component bore portion T 171 , 
         [0088]    a shoulder  27  joining the proximal portion  25  of the element and the distal portion  26  of the element. 
         [0089]    As has already been explained, the element illustrated in  FIGS. 11 to 13  is a screw  14 , of which the head  28  comprises the distal portion  26  of the element, and of which the threaded shank  29  constitutes at least in part the proximal portion  25  of the element. 
         [0090]    As is illustrated in  FIGS. 8 and 9 , when the axial limit stop device  1  is engaged in the bore  17  with its angular portions  3  and  4  engaged in the retaining seats  19  and  20  ( FIG. 8 ), the distal element portion  26  of the screw  14  bears on the first ends  3   a  and  4   a  of the angular portions  3  and  4  along the shoulder  27 . The axial bearing of the shoulder  27  against the first ends  3   a  and  4   a  and the axial bearing of the second free ends  3   b  and  4   b  against the proximal faces  21  and  22  allow the screw  14  to be retained axially in the bore  17  of the component, which is here represented by the transfixed multiple dental prosthesis  11 . 
         [0091]    The screw  14  can then be manipulated in turn, by driving it in rotation about the central axis I-I by means of a screwing tool engaged in the access well  15 , in order to fix the transfixed multiple dental prosthesis  11  on the dental implant  12 . 
         [0092]    If the screw  14  has been damaged by application of an excessive rotational torque or by any other means, it is necessary that it can be extracted from the bore  17 . 
         [0093]    To do this, the axial limit stop device  1  is turned about the first longitudinal axis II-II (by means of the notches  9  and  10 ) in such a way as to bring the angular portions  3  and  4  against the angular parts  23  and  24  of the lateral surface T 172   a  of the second component bore portion T 172 . The angular portions  3  and  4  are thus brought back to the retracted position, such that they no longer protrude radially in the retaining seats  19  and  20 . The axial limit stop device  1  can then be extracted from the component bore  17 , via the first component bore portion T 171 , by a simple movement of axial translation along the first longitudinal axis II-II and in the direction of the orifice  18  of the component bore  17 . 
         [0094]      FIGS. 14 to 17  illustrate a mounting tool  30  for mounting an axial limit stop device  1  in the bore  17  of the transfixed multiple dental prosthesis  11 . As will be seen more particularly from  FIGS. 14 and 15 , the mounting tool  30  has a tubular sleeve  31  with a central bore  32  extending along a second longitudinal axis III-III between a distal orifice  33  and a proximal orifice  34 . It will additionally be seen that: 
         [0095]    the central bore  32  of the tubular sleeve  31  has a tubular sleeve distal bore portion T 310  extending from the distal orifice  33 , a tubular sleeve intermediate bore portion T 311  following on from the tubular sleeve distal bore portion T 310  and extending toward the proximal orifice  34 , and a tubular sleeve proximal bore portion T 312  following on from the tubular sleeve intermediate bore portion T 311  and extending as far as the proximal orifice  34 , 
         [0096]    the tubular sleeve intermediate bore portion T 311  has a circular cross section of diameter D 4  equal to or slightly greater than the external diameter D 2  of the annular ring  2 , 
         [0097]    the tubular sleeve distal bore portion T 310  has two retaining seats  35  and  36  which extend radially with respect to the second longitudinal axis III-III out from the volume of the cylinder C 3  continuing the cylindrical surface of the tubular sleeve intermediate bore portion T 311 , the retaining seats  35  and  36  being able to receive the angular portions  3  and  4  of the axial limit stop device  1  in the protruding position. 
         [0098]    The retaining seats  35  and  36  each have a proximal retaining face  37  or  38 , respectively, extending along a transverse plane P 3  substantially perpendicular to the second longitudinal axis III-III and connecting to the cylindrical lateral wall of the tubular sleeve intermediate bore portion T 311 . 
         [0099]    The tubular sleeve distal bore portion T 310  has two angular parts  39  and  40  of the lateral surface extending in the continuation of the cylindrical lateral surface of the tubular sleeve intermediate bore portion T 311 . The angular parts  39  and  40  are included within the diametric lines indicated by broken lines in  FIG. 15 . Each retaining seat  35  and  36  is separated from the adjacent retaining seat  35  or  36  by an angular part  39  or  40 . 
         [0100]    It will be seen more particularly in  FIGS. 16 and 17  that the mounting tool  30  likewise has a longitudinal shaft  41  extending along a third longitudinal axis IV-IV, with a distal portion T 410  having a circular outer cross section of diameter D 5  substantially equal to the diameter D 4  of the tubular sleeve intermediate bore portion T 311 . The distal portion T 410  of the longitudinal shaft extends along the third longitudinal axis IV-IV by a length L 1  greater than the sum of the lengths (along the second longitudinal axis III-III) of the tubular sleeve intermediate bore portion T 311  and of the tubular sleeve distal bore portion T 310 . The engagement of the distal portion T 410  of the longitudinal shaft in the tubular sleeve intermediate bore portion T 311  and the tubular sleeve distal bore portion T 310  can thus eject from the tubular sleeve  31  an axial limit stop device  1  which would be inserted in the tubular sleeve distal bore portion T 310 . 
         [0101]    To move the axial limit stop device  1  in rotation with respect to the tubular sleeve  31  about the second longitudinal axis III-III, it will be seen that: 
         [0102]    the distal portion. T 410  of the longitudinal shaft has, at a free end T 410   a , a distal face  42  intended to bear against the proximal end  2   a  of the annular ring  2 , 
         [0103]    the distal face  42  of the distal portion T 410  of the longitudinal shaft has raised areas, specifically two tongues  43  and  44 , which are able to cooperate with the indentation  7  formed in the face  8  of the proximal end  2   a  of the annular ring  2  (by engaging in the notches  9  and  10 ) in order to drive the annular ring  2  in rotation about its central axis I-I with respect to the tubular sleeve  31 . A use of the mounting tool  30  to insert and fix an axial limit stop device  1  in the bore  17  of a transfixed multiple dental prosthesis  11  will be explained below with the aid of  FIGS. 16 to 21 . 
         [0104]    The axial limit stop device  1  is first of all inserted with a translation movement, illustrated by the arrow  45  in  FIGS. 16 and 17 , into the tubular sleeve distal bore portion T 310 . During this insertion, the angular portions  3  and  4 , in the protruding position, are received in the retaining seats  35  and  36  while the annular ring  2  is received in the tubular sleeve intermediate bore portion T 311 . 
         [0105]    After this assembling of the tubular sleeve  31  and of the axial limit stop device  1 , the longitudinal shaft  41  is inserted into the central bore  32  of the tubular sleeve  31  from the proximal orifice  34  toward the distal orifice  33 , according to the movement illustrated by the arrow  46  in  FIGS. 18 and 19 . 
         [0106]    The longitudinal shaft  41  is inserted into the central bore  32  until the tongues  43  and  44  engage in the notches  9  and  10 , as is illustrated in  FIG. 19 . 
         [0107]    The practitioner then moves the longitudinal shaft  41  in rotation about the second longitudinal axis III-III (coinciding with the central axis I-I and the third longitudinal axis IV-IV), in such a way as to bring the angular portions  3  and  4  into line with the angular parts  39  and  40  of the tubular sleeve distal bore portion T 310  (movement illustrated by the arrow  47  in  FIG. 19 ). The angular portions  3  and  4  are thus brought back to a retracted position. 
         [0108]    The assembly formed by the axial limit stop device  1  (with its angular portions  3  and  4  in the retracted position), the tubular sleeve  31  and the longitudinal shaft  41  is then arranged with the central axis I-I, the second longitudinal axis III-III and the third longitudinal axis IV-IV coinciding with the first longitudinal axis II-II as illustrated in  FIG. 20 . 
         [0109]    The assembly formed by the axial limit stop device  1 , the tubular sleeve  31  and the longitudinal shaft  41  is then moved until the distal orifice  33  of the tubular sleeve  31  comes into contact with the inlet orifice  18  of the component bore  17  as illustrated in  FIG. 21 . The longitudinal shaft  41  is then moved with respect to the tubular sleeve  31  according to the axial translation movement illustrated by the arrow  48 . The longitudinal shaft  41  then pushes the axial limit stop device  1  (with its angular portions  3  and  4  in the retracted position) through the first component bore portion T 171  until the angular portions  3  and  4  come into line (axially) with the second component bore portion T 172 . At that moment, if the angular portions  3  and  4  are likewise located in line (radially) with the retaining seats  19  and  20 , they are elastically returned to the protruding position and penetrate radially into the retaining seats  19  and  20 . The axial limit stop device  1  is thus duly installed in the bore  17 , as illustrated in  FIGS. 8 and 9 . In the case where the angular portions  3  and  4  are located in line with the angular parts  23  and  24  and thus remain in the retracted position in the second component bore portion T 172 , a rotation movement illustrated by the arrow  49  can be applied to the axial limit stop device  1  by the longitudinal shaft  41  in such a way as to bring the angular parts  3  and  4  into line with the retaining seats  19  and  20  and permit the movement of the angular portions to the protruding position. 
         [0110]    The screw  14  can be installed in the bore  17  prior to the insertion of the axial limit stop device  1  into the bore  17 . Alternatively, before the axial limit stop device  1  has been inserted into the tubular sleeve distal bore portion T 310 , it is also possible to insert the screw  14  through the axial limit stop device  1  until the shoulder  27  comes to bear on the angular portions  3  and  4 . It is then the subassembly formed by the axial limit stop device  1  and the screw  14  that is simultaneously pushed axially into the bore  17  during the relative translation movement, illustrated by the arrow  48  in  FIG. 21 , between the tubular sleeve  31  and the longitudinal shaft  41 . 
         [0111]    To disassemble the axial limit stop device  1 , the latter is moved in rotation about the central axis I-I until the angular portions  3  and  4  are brought back to the retracted position by cooperation with the angular parts  23  and  24  of the component bore  17 . This can be accomplished by using the longitudinal shaft  41  and its tongues  43  and  44 . 
         [0112]    The axial limit stop device  1  (and the screw  14 ) can then be pushed in the direction of the inlet orifice  18  out of the bore  17  by a pusher tool (a rod for example) bearing against the axial limit stop device  1  (and/or the screw  14 ) by passing through the access well  15 . 
         [0113]    In a first variant illustrated in  FIG. 9 , the dental implant  12  is in just one piece, and its upper end  12   a  is intended to pass at least partially through the mucosa. 
         [0114]    In a second variant illustrated in  FIG. 22 , the dental implant  12  is in two pieces, being composed of an osseous anchor  120  and of a transmucosal extension  121 . The transmucosal extension  121  has an upper end  121   a  intended to pass at least partially through the mucosa. 
         [0115]    The present invention is not limited to the embodiments that have been explicitly described, and instead it includes the different variants and generalizations contained within the scope of the attached claims.