FR2778553A1 - Dental pin with composite retaining-profile - Google Patents

Abstract

The pin (1) has a mono bloc structure with a shaped conical base (14) secured in the root canal and head (4) securing the false tooth or cast. The circumference groove (6) is closer to the top end (8) of the pin (1) than the projection (7), with the longitudinal groove (15) running between projection (7) and groove (6). The entry and release surfaces (9,10) have shallow angle of contact with the tooth.

Description

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MIXED RETENTION DENTAL PIVOT

  The present invention relates to dental pivots used for the reconstruction and / or at least temporary holding

dentures.

  Dental pivots generally consist of a monobloc body comprising a distal root rod intended to be introduced into a dental root canal, and a proximal anchoring head intended to receive and retain an impression or a dental prosthesis. The proximal anchoring head includes circumferential retention reliefs intended to be embedded in the material constituting the impression or the dental prosthesis for

ensure their axial retention.

  We mainly know two families of dental pivots which are distinguished by the shape of their reliefs

retention circumferentials.

  According to a first family, the dental pivots have circumferential retention reliefs in the form of continuous annular grooves, as described in the document FR 2 538 696 A, or as manufactured and distributed for more than twenty years by the

ANTHOGYR company.

  According to the second family, the dental pivots have circumferential retention reliefs in the form of annular ribs, as described in particular in documents EP 0 123 006 A, WO 79/00275 A, US 5,236,361 A, FR 2 516 376 A, or

FR 2 745 352 A.

  A problem frequently encountered in dental pivots is to ensure sufficient axial retention of the pivot head in the impression or the dental prosthesis, without however degrading the impression in the event of untimely or voluntary extraction of the pivot, to allow its subsequent repositioning and its

  subsequent satisfactory retention in the imprint.

  To increase the axial retention capacities, it has been proposed, as described in the documents cited above, to provide a plurality of circumferential retention reliefs

  distributed along the pivot head.

  However, it can be seen that the multiplication of the circumferential retention reliefs does not provide the results hoped for after repositioning of the pivot following an extraction.

  inadvertent or voluntary of the pivot out of the dental impression.

  In addition, the multiplication of the circumferential retention reliefs induces an uncertainty in the axial repositioning of the pivot in the dental impression following an untimely or voluntary extraction, and an erroneous axial repositioning generally induces an error in the form of prosthesis with

  achieve, and reduced axial holding capacity.

  The problem proposed by the present invention is to design a new dental pivot structure which has improved axial retention capacities, in particular after an untimely or voluntary extraction of the pivot from a dental impression. Another object of the invention is to avoid any deterioration of the dental impression during an untimely or voluntary extraction of the pivot, in particular in the area of the

  entrance lips of the hole made in the impression paste.

  The invention results from the observation that, in known structures having several circumferential retention reliefs, the successive passage of several circumferential retention reliefs over the same retention area of the impression paste, during the extraction and reintroduction of the pivot, produces a degradation of the corresponding retention area of impression paste and a significant reduction in the

  subsequent axial retention capacity of the pivot in the impression.

  To solve this problem as well as others, the invention provides a monobloc dental pivot, comprising a distal root rod shaped to be introduced into a dental root canal, and a proximal anchoring head intended to receive and retain an impression. or a dental prosthesis, the proximal anchoring head having a proximal end and circumferential retention reliefs intended to be embedded in the material constituting the impression or the dental prosthesis to ensure their axial retention; the circumferential retention reliefs include: - a circumferential retention groove, - and a circumferential retention projection, - the circumferential retention groove being closer to the proximal head end than the circumferential retention projection. The circumferential retention groove is intended to cooperate with a first retention zone in the form of a circumferential rib in the prosthesis or the impression paste. The circumferential retention projection is intended to cooperate with a second retention zone in the form of a groove

  circumferential in the prosthesis or impression paste.

  Thanks to this particular structure of circumferential retention reliefs according to the invention, each dental paste retention zone is only requested once for each movement of extraction or introduction of the pivot, which considerably limits the risks of degradation and best ensures the integrity of the pivot's axial retaining capacities in

impression or prosthesis.

  According to an advantageous embodiment, the proximal anchoring head further comprises at least one longitudinal groove, cutting at least the circumferential retention groove, and

  interrupted set back from the proximal end of the head.

  It has been observed that this particular structure with a longitudinal groove still considerably improves the axial retention capacity of the pivot in the dental impression. This improved axial retention capacity probably results from the fact that each longitudinal groove in the dental pivot produces, in the dental impression paste, a longitudinal rib which reinforces the circumferential rib of impression paste coming to lodge in the circumferential retention groove. : each longitudinal rib of impression paste opposes the bending of the circumferential rib of impression paste during a

  attempt to extract the dental pivot.

  In addition, each longitudinal rib in the impression paste has good mechanical strength in its longitudinal direction, to oppose the withdrawal of the dental pivot by pressing against the proximal end of the longitudinal groove.

of dental pivot.

  Also, each longitudinal groove improves the angular retention capacity of the provisional prosthesis on the

dental pivot.

  Preferably, the circumferential retention projection has a lateral profile with an attack face and a gently sloping trailing face forming with the adjacent peripheral head surface.

  an angle greater than about 140.

  In an advantageous embodiment, the circumferential retention projection has the shape of an O-ring, the cross section of which forms an angle of less than approximately 80. Preferably, the O-ring has an angle

about 600.

  Good results are obtained by providing a circumferential retention projection height of less than 0.15 mm.

  approximately, advantageously equal to approximately 0.10 mm.

  It will be advantageous to place the circumferential retention groove in the immediate vicinity of the proximal end of the pivot head. Indeed, by this arrangement, the hole made in the impression paste comprises a cylindrical section of great length which ensures effective guiding of the pivot until engagement of the

  circumferential retention reliefs.

  Other objects, characteristics and advantages of the

  present invention will emerge from the following description of modes

  of particular embodiments, made in relation to the appended figures, among which: - Figure 1 is a perspective view of a dental pivot according to an embodiment of the present invention; - Figure 2 is a front view of the dental pivot of Figure 1; - Figure 3 is a side view in section B-B of the dental pivot of Figure 2; and FIG. 4 is a front view in section of a dental pivot according to the invention, engaged in a dental root canal and

  supporting an impression or dental prosthesis.

  In the embodiment illustrated in the figures, a dental pivot according to the invention is a one-piece body comprising a distal root rod 1 shaped to be introduced into the dental canal 2 of a dental root 3 illustrated in FIG. 4, and a proximal head 4 for receiving and retaining

  a dental impression or prosthesis 5.

  The proximal anchoring head 4 comprises a circumferential retention groove 6 and a circumferential retention projection 7, the circumferential retention groove 6 being closer to the proximal end 8 of the head 4 than the projection

circumferential retention 7.

  The circumferential retention projection 7 has a lateral profile with an attack face 9 and a trailing face 10 on a gentle slope, making with the corresponding adjacent peripheral surface 11 or 12 of the head 4 a respective angle A or C

greater than about 140.

  In the illustrated embodiment, the circumferential retention projection 7 has the shape of an O-ring, the cross section of which makes an angle D less than approximately. In the figures, the O-ring has an angle D of about 60. The adjacent peripheral surfaces 11 and

12 can be cylindrical.

  The height H of the circumferential retention projection 7 is preferably less than approximately 0.15 mm. Good results of axial retention of the pivot are obtained with a height H equal to

0.10 mm approximately.

  The circumferential retention groove 6 can advantageously be arranged in the immediate vicinity of the proximal end 8 of the head. In the embodiment illustrated in the figure, the distance between the circumferential retention groove 6 and the proximal end 8 of the head is less than 1.5 mm. We will be able to

choose a shorter distance.

  The circumferential retention groove 6 can advantageously have a V-shaped lateral profile, as illustrated, with lateral faces open at an angle E of approximately 120 and a depth of approximately 0.16 mm, between two adjacent surfaces

may be cylindrical.

  The distal root stem 1 comprises a cylindrical proximal section 13, connected to the head 4, and a distal section 14

  conical, the cone angle of which can be from 5 to 10 approximately.

  In the embodiment illustrated in FIGS. 1 to 3, the proximal anchoring head 4 further comprises at least one longitudinal groove 15, cutting at least the circumferential retention groove 6, and interrupted at its proximal end 16 set back from the proximal end 8 of head 4. The longitudinal groove 15 can have a width of approximately 0.2 to 0.4 mm, and the bottom of the longitudinal groove 15 can have a circular longitudinal profile, as seen in FIG. 3, within a radius of 5 to

mm approx.

  A dental pivot according to the invention can be made of metal, to constitute a temporary or permanent pivot, or a test pivot allowing the creation of a dental impression of polymerizable paste. Also, a pivot according to the invention can be made of a burn-out material, constituting a pivot which is just adapted in place of the metallic impression-taking pivot for the casting of the metallic core of a prosthesis to

ceramic outer surface.

  Referring to Figure 4, we see that the orifice 17 of the dental channel 2 is generally flared. As a result, when the impression is taken, the material constituting the impression 5 fills the inlet of the orifice 17 around the root rod 1 and the proximal anchoring head 4, constituting a lip 18 with a thin edge and therefore particularly fragile. When removing the imprint 5, it is generally sought that the pivot remains

  secured to the impression 5 and therefore withdraws from the dental canal 2.

  If it is impossible to withdraw the root stem 1 from the dental canal 2, for example in the presence of several pivots introduced into non-parallel dental canals, or in the event of too strong adhesion of the root stem 1 in the dental canal 2, the pivot head 4 emerges from the corresponding hole in the cavity 5. When it leaves, the circumferential retention projection 7 with an inclined attack and flight face does not alter the lip 18, and the circumferential groove of retention 6 does not alter the circumferential groove of the second retention zone intended to retain the circumferential retention projection 7. The practitioner then removes the pivot from the dental canal 2, and

  reintroduces the head 4 into the corresponding hole of the imprint 5.

  During this reintroduction, the practitioner does not encounter any significant axial resistance as long as the circumferential rib 19 of the impression 5 does not abut against the proximal end 8 of the head. By forcing axially, the practitioner causes the withdrawal of the circumferential rib 19 and allows the axial progression of the pivot without further resistance until the introduction of the circumferential rib 19 of impression in the circumferential retention groove 6 of the pivot. At this same instant, the circumferential pivot retention projection 7 engages in the

  corresponding circumferential groove 20 of imprint.

  It is understood that, with the particular arrangement of the circumferential retention reliefs 6 and 7 according to the invention, the corresponding retention zones 19 and 20 of the imprint 5 are not appreciably degraded during removal and

reintroduction of the pivot.

  In addition, the practitioner cannot make an error in axial positioning of the pivot in the impression 5, since the only possible axial position of retention of the pivot in the impression is the position in which the two circumferential retention reliefs 6 and 7 are engaged in the correct retention position in the corresponding retention zones 19 and 20 of the impression 5. The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants thereof. and generalizations contained in the field

of the claims below.

Claims (8)

  1 - Monobloc dental pivot, comprising a distal root rod (1) shaped to be introduced into a dental canal (2) of dental root (3), and a proximal head (4) for anchoring intended to receive and retain an impression or a dental prosthesis (5), the proximal anchoring head (4) having a proximal end (8) and circumferential retention reliefs intended to be embedded in the material constituting the impression or the dental prosthesis (5) to ensure their axial retention, characterized in that the circumferential retention reliefs comprise: - a circumferential retention groove (6), and a circumferential retention projection (7), - the circumferential retention groove (6) being closer to the end proximal (8) head (4) than the projection   circumferential retention (7).   2 - Dental pivot according to claim 1, characterized in that the proximal anchoring head (4) further comprises at least one longitudinal groove (15), cutting at least the circumferential retention groove (6), and interrupted in withdrawal of   the proximal end (8) of the head (4).   3 - Dental pivot according to claim 2, characterized in that the longitudinal groove bottom (15) has a profile longitudinal circular.   4 - Dental pivot according to any one of   Claims 1 to 3, characterized in that the projection   circumferential retention (7) has a lateral profile with a leading face (9) and trailing face (10) in a gentle slope making with the adjacent peripheral surface (11, 12) of head (4) a   angle (A, C) greater than about 140.   - Dental pivot according to claim 4, characterized in that the circumferential retention projection (7) has   an O-ring shape with an angle (D) less than about 80.   6 - Dental pivot according to claim 5, characterized   in that the O-ring has an angle (D) of about 60.   7 - Dental pivot according to one of claims 5 or 6,   characterized in that the height (H) of the circumferential retention projection (7) is less than 0.15 mm   approximately, advantageously equal to approximately 0.10 mm.   8 - Dental pivot according to any one of   Claims 1 to 7, characterized in that the groove   circumferential retention (6) is arranged nearby   immediately to the proximal end (8) of the head (4).   9 - dental pivot according to claim 8 characterized in that the circumferential retention groove (6) has a lateral V-shaped profile, with lateral sides open according to a   angle (E) of approximately 120 and a depth of approximately 0.16 mm.   - Dental pivot according to any one of   Claims 1 to 9, characterized in that the root stem (1)   distal comprises a cylindrical proximal section (13) connected to the   head (4), and a distal conical section (14).