FR2523838A1 - Threaded stud for tooth rebuilding - has thread of very fine pitch to avoid cracking root - Google Patents

Abstract

The threaded stud forms a channel anchorage for material used in rebuilding a tooth, it comprises a protruding and profiled head (1) integral with a threaded shank (2) inserted and sealed in the dental channel after drilling and then screwed home for part of a turn to increase its grip. To improve the grip still further and avoid the risk of cracking or bursting of the root, the thread (7) is of very fine pitch, between 0.2 and 0.45 mm for a shank diameter between 1.2 and 1.7 mm. The angle of the triangular-profile thread is approximately 60 deg.

Description

Threaded post for canal anchoring of the tooth reconstruction material.

 The present invention relates to a threaded post for anchoring the material for reconstituting a tooth.

 Such threaded studs are known and comprise a profiled projecting head integral with a threaded rod intended to be introduced and sealed in the dental canal after reaming, then screwed on about a quarter turn to increase its holding.

 The thread is intended to improve the anchoring by presenting, on the one hand, recesses for the penetration of the sealing material and, on the other hand, protrusions intended to penetrate, during rotation, in the tissue of the root. . The constant trend of the manufacturers of these threaded studs has been and still is to give the threads the largest projection compatible with the diameter of the rod. Thus, for the conventional dimensional range of threaded studs1 the thread pitch varies between 0.5 and 0.7 mm. The set objective is achieved to the apparent satisfaction of professionals, although they are very careful not to screw the post too much to avoid cracking or even bursting of the dental root. In fact, this is a major drawback which everyone accommodates without having found a satisfactory remedy to date. To this drawback is added another which depends on it; in fact, the dentist generally does not screw the post enough, to precisely avoid the risk indicated above and the anchoring which results therefrom is not as solid as it could be; moreover, if the screwing is carried out at the breaking limit, it is quite obvious then that the reconstituted tooth intrinsically has a certain brittleness whose consequences do not appear until later.

 The head is profiled to present undercut hollows in order to obtain the retention of the reconstitution material. The result is not as satisfactory as one would think.

 The present invention therefore aims to remedy these drawbacks by improving the anchoring of the threaded rod in the root and the retention of the reconstitution material on the head.

 For this purpose and in accordance with the invention, the thread pitch is much finer and between 0.2 and 0.45 mm for a rod diameter. Taken between 1.2 and 1.7 mm, the angle of the triangular net being approximately 600.

 Thus, for the same screwing rotation (generally a quarter turn), the axial penetration stroke of the rod in the channel is reduced and the risk of cracking or bursting of the root annihilated t it is even possible to increase the angular amplitude of the rotation without the breaking limit stroke being reached, or even approached. In addition, the attachment of the thread in the root tissue is contrary to what was expected, much better than before, due to the cutting edge of the thread and the limited unit penetration, thus avoiding localized repression.

 Preferably, the thread pitch is 0.2 mm for a rod diameter between 1.2 and 1.3 mm, 0.30 mm for a rod diameter between 1.4 and 1.5 mm, 0.35 mm for a rod diameter between 1.6 and 1.7 mm.

 According to the invention, the rod is cylindrical-conical, the cylindrical part preferably extending over substantially 2/3 of the length.

 Therefore, the nesting in the root is much better without noticeable weakening of the remaining canal wall.

 Still according to the invention, the head comprises projecting at least two annular flanges of substantially triangular section, separated by at least one anchoring groove (10) and truncated by two flats substantially parallel to each other.

 Under these conditions, the retention of the reconstitution material is improved in the axial direction by the grooves and tangential by the flats.

 Various other characteristics and advantages of the invention will also emerge from the detailed description which follows.

 An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

On this drawing
- Figure 1 is a perspective illustrating the threaded post according to the invention.

 - Figure 2 is a partial elevation taken along arrow F of Figure 1.

 As shown in the drawing, the post has a head 1 secured to a threaded rod 2.

The rod 2 has a cylindrical part 3 extending by a conical end part 4. The cylindrical part extends substantially over 2/3 of the length L of the rod and the conical part over the remaining 1/3. Said rod is smooth at 5 and 6, respectively under the head 1 and at the end; between these smooth portions S, 6, a very fine thread 7 is shaped. It is a simple triangular thread having a sharp and sharp angle at the top of 600. In the example chosen, the pitch is
- 0.25 mm for a diameter of 1.2 or 1.3 mm,
- 0.30 mm for a diameter of 1.4 or 1.5 mm,
- 0.35 mm for a diameter of 1.6 or 1.7 mm.

 It is obvious that the pitch can be a little less or a little finer and in this case the experimental limits are 0.2 and 0.45 mm respectively.

 The head 1 has projecting three annular flanges 8, 9 and 10 of substantially triangular section; they are separated by grooves 11 and 12 for the retention of the reconstitution material in the axial direction. Furthermore, two flats 13 and 14 substantially parallel to each other are cut in the head over the height of the two extreme flanges 8 and 9; these flats improve the retention of the reconstitution material in the tangential direction. Of course, the flanges can be more or less numerous and the flats shaped differently and in greater number.

 The invention is not limited to the embodiment shown and described in detail, since various modifications can be made thereto without departing from its scope.

Claims (5)

 1.- Threaded post for canal anchoring of the material for reconstituting a tooth, comprising a profiled projecting head (I) integral with a threaded rod (2) intended to be introduced and sealed in the dental canal after boring, then screwed onto a portion of a tower to increase its strength,  characterized in that, to further improve the grip and eliminate the risk of cracking or even bursting of the root, the pitch of the thread (7) is much finer and between 0.2 and 0.45 mm for a diameter of rod between 1.2 and 1.7 mm, the angle of the triangular thread being approximately 600.  2.- threaded pin according to claim 1, characterized in that the thread pitch (7) is 0.25 mm for a rod diameter between 1.2 and 1.3 mm, 0.30 mm for a rod diameter between 1.4 and 1.5 mm, 0.35 mm for a rod diameter between 1.6 and 1.7 mm.  3.- threaded pin according to claim 1 or 2, characterized in that the rod (22) is cylindroconical, the cylindrical part (3) preferably extending over substantially 2/3 of the length.  4.- threaded pin according to any one of claims 1 to 3, characterized in that the head projecting at least two annular flanges (8, 9) of substantially triangular section, separated by at least one groove (10) d anchoring and truncated by two flats (13, 14) substantially parallel to one another.  5.- threaded pin according to claim 4, characterized in that the head has three annular flanges (8 to 10), the two ends (8,9) of which are only truncated by the flats (13, 14).