ANGLE PIECE HEAD

Abstract

The angle piece head drives an instrument for operating on dental roots and includes a body having a generally cylindrical cavity and an instrument-holding core in the cavity. The core is shaped to receive and hold the instrument and moves axially and pivotally. The instrument-holding core includes a groove having an offset engaging therewith. The offset engages with one or the other of the two edges of the groove such that the rotation thereof transmits an alternating axial movement to the instrument while enabling same to rotate about the axis of the instrument. The groove includes two portions that extend on either side of a median area. For each portion, the height, namely the distance that separates the two edges, increases from the median area to each end of the groove.

Claims

1. A counter-angle head for driving an instrument for procedures on dental roots, comprises: a body being comprised of: a generally cylindrical cavity; and an instrument holder core, being generally cylindrical, configured to receive and maintain said instrument, and moveable axially and by pivoting, said instrument holder core being comprised of a lateral groove formed on a circumference portion and with an orientation perpendicular to an axis of the core; and an eccentric supported at an end of a rotary shaft, said eccentric being cooperative with at least one of two edges of said groove, said two edges being a driving edge and a return edge, wherein rotation of said eccentric communicates an axial alternating movement to said instrument while leaving said instrument a possibility of rotational movement around an axis of said instrument, wherein said groove or slot comprises two parts extending on either side of a median zone, for each of which the height, i.e., the distance that separates the driving edge and the return edge, increases from said median zone toward each of the ends of said groove.

2. The counter-angle head, according to claim 1, wherein height of the groove at each of the ends of the two parts is greater than or equal to the value of the diameter of the eccentric increased by twice the value of the eccentricity, and wherein height of the groove in its median zone is comprised between the height of the groove at each of the ends of said two parts, the value of the diameter of the eccentric being increased by the eccentricity value.

3. The counter-angle head, according to claim 1, wherein each of the two parts of the groove has an incline relative to a circumference line, the extreme side parts of said groove moving away from the side of the core by which said instrument is maintained.

4. The counter-angle head according to claim 3, wherein a slope of the side parts of the groove is from 5° to 15° relative to a circumference line.

5. The counter-angle head according to claim 3, wherein a slope of the side parts of the groove is determined based on the weight of the core and the instrument that it holds, this slope decreasing at the same time as this weight.

6. The counter-angle head, according to claim 1, wherein said groove extends over an angular sector greater than or equal to 100°.

7. The counter-angle head, according to claim 1, wherein said eccentric is trimmed with a shock absorbing material.

8. The counter-angle head, according to claim 7, wherein said shock absorbing material assumes the form of a ring.

9. The counter-angle head, according to claim 1, wherein connection between the instrument and the instrument holder core is done through maintaining means associated with means for indexing the angular position of said instrument relative to said core.

10. The counter-angle head according to claim 7, wherein the indexing means is comprised of matching cavities.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0027] The advantages and features of the counter-angle head according to the invention will emerge more clearly from the following description relative to the appended drawing, which shows one non-limiting embodiment thereof.

[0028] In the appended drawing:

[0029] FIG. 1 shows a schematic sectional view along a diametric median plane of a counter-angle head according to the invention.

[0030] FIG. 2 shows a schematic perspective view of part of the same counter-angle head.

[0031] FIG. 3 shows an elevation view of the same part.

DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows a counter-angle head 1 according to the invention, which comprises, in a manner known in itself, a body 2 in which a cylindrical cavity 20 is arranged, where an instrument holder core 3 is housed. The core 3 includes means 30 for immobilizing an instrument, not shown, able to maintain said instrument along the axis X of the core 3.

[0033] One can see in FIG. 1 that the core 3 includes, on the periphery, in its cylindrical wall, a groove or slot 31 in which an eccentric 4 secured to a rotary shaft 40 can be placed. Under the action of the rotation of the rotary shaft 40 along the axis Y, the eccentric 4, which is off-centered by a value E, alternately comes into contact with a driving edge 32 and a return edge 33 of the groove or slot 31, so as to communicate an alternating axial movement, in directions C and R, respectively, to the core 3 and therefore to the instrument that it holds.

[0034] FIGS. 2 and 3 show that the groove or slot 31 extends over an angular sector, in the case at hand, non-limitingly, of 120°, and that it includes two parts 34 and 35, extending symmetrically on either side of a median zone 36, while describing an incline such that their end moves away from the side 37 of the core 3 from which the instrument protrudes, not shown.

[0035] Furthermore, the distance H1 separating the driving edge 32 from the return edge 33 at the median zone 36 is smaller than the distance H2 separating the driving edge 32 from the return edge 33 at each of the ends of the parts 34 and 35.

[0036] Note will be made that due to the incline of the parts 34 and 35, the difference in dimensions of H1 and H2 is reflected by the fact that the angle α formed by the return edge 33 of one or the other of the parts 34 and 35 with a circumference line L is larger than the angle β formed by the driving edge 32 with the same line. In the case at hand, the angle α is equal to 9°, while the angle β is equal to 6°.

[0037] That being said, the height H2 is greater than or equal to the value of the diameter of the eccentric 4 increased by twice the eccentricity value E, such that the rotation of the eccentric 4 at the ends of the groove or slot 31 does not create any vibration.

[0038] The height H1 is smaller than H2 and larger than the value of the diameter of the eccentric 4 increased by the eccentricity value E.

[0039] Thus, as a non-limiting example, the eccentric 4 has a diameter of 2.6 mm, it is off-centered by 0.3 mm, H1 is equal to 2.95 mm and H2 is equal to 3.20 mm, such that a mandatory minimum vibration of 0.25 mm is obtained at the center of the groove or slot 31, at H1, which will decrease the more the eccentric 4 moves toward the ends of one or the other of the parts 34 or 35, to arrive at a mandatory zero movement.

[0040] The movement of the core 3 will depend on the frictional forces on the walls of the channel encountered by the endodontic instrument mounted on this core 3.

[0041] With low frictional forces, the longitudinal movement of the instrument will have, at H1, a total amplitude corresponding to twice the eccentricity value E, increased by the difference between H1 and the diameter of the eccentric 4 increased by the eccentricity value E.

[0042] With increased frictional forces, the pressure of the active elements, blades, of the endodontic instrument on the ductal walls causes the instrument, therefore the core 3, to rotate in the cavity 20, such that the eccentric 4 again acts in zones of the slit or groove 31 where the height is comprised between H1 and H2, and therefore generates a lower, or even zero, amplitude of the movement of the instrument.

[0043] Furthermore, over the course of the revolutions of the eccentric, the friction of the blades of the endodontic instrument decreases, and the influence of the helix angle of the blades of the instrument for one rotation of the core lessens. The instrument holder core 3 should then be allowed to return to a zone where the mandatory movement is greater, i.e., a more central zone 36 of the slit or groove 31.

[0044] It is with this aim that the slot or groove 31 has a positive slope of its end parts 34 and 35, which may be more or less pronounced based on the weight of the core 3 equipped with the instrument. Thus, very quickly, once the friction of the blades of the endodontic instrument on the walls of the channel disappears, the eccentric 4 regains a more central rotation in the groove or slot 31.

[0045] These various implemented methods make it possible to greatly reduce the “jackhammer” effect previously described, and above all, the suction effect of the Hedstroem file when the latter is experiencing strong friction with the walls of the channel.

[0046] Furthermore, the operator, through bearing, then traction movements with a low amplitude on the counter-angle, can influence the mandatory vibration amplitude of the file: slight bearing accentuates the pressure of the file on the walls of the channel and causes a low-amplitude mandatory vibration, slight traction makes it possible to extricate the file from overly pronounced friction with a low vibrational amplitude for a low-friction zone allowing a more pronounced vibration.

[0047] It will also be noted that in order to reduce the vibration created by the impact of the eccentric 4 on the edges 32 and 33 of the groove or slot 31, the eccentric 4 is trimmed, in the form of a ring 41, for instance, with a shock absorbing material that may for example, non-limitingly, be “Declafor-THX”.

[0048] It will also be noted that if endodontic instruments with a non-round section, for example ovoid, are used, means are provided for indexing the position of the instrument relative to the core 3, these means preferably assuming the form of matching cavities preferably included by the means 30 and the instrument.