AN ORTHODONTIC LIGATURE

Abstract

An orthodontic ligature for securing an orthodontic archwire to an orthodontic bracket. The orthodontic ligature is formed of a resilient band which forms a flap. The flap forms a grip portion. The resilient band defines a non-circular hole having a major dimension along the direction in which the grip portion extends. The invention provides an easy to use orthodontic ligature which further is maximized in durability.

Claims

1. An orthodontic ligature for securing an orthodontic archwire to an orthodontic bracket, the orthodontic ligature being formed of a resilient band which extends along a center axis of the resilient band, wherein the resilient band extends with the center axis circumferentially along a closed path and essentially in a plane, wherein the band further forms a flap which extends in a direction essentially parallel to said plane, the flap forming a grip portion, and wherein the resilient band defining a hole forming a through-hole extending through the orthodontic ligature in a dimension perpendicular to the plane, wherein the hole in dimensions along the plane is overall keyhole-shaped or oval and having a major dimension along the direction in which the grip portion extends.

2. The orthodontic ligature of claim 1, having a retainer protruding from the flap in a dimension generally perpendicular from the plane.

3. The orthodontic ligature of claim 2, having on each of opposite sides of the flap a pair of retainers with the pair of retainers being spaced from each other.

4. The orthodontic ligature of claim 2, wherein the retainer(s) is/are bar-shaped, extending generally transverse to the greatest dimension of the hole.

5. The orthodontic ligature of claim 1, wherein the band extends along only a section of the circumference at a generally uniform cross-section and the other section of the circumference forms the flap.

6. The orthodontic ligature of claim 5, wherein at least the uniform cross-section in the dimension along the plane has a size which essentially corresponds to the size of the hole in the same dimension.

7. The orthodontic ligature of claim 5, wherein at least the uniform cross-section extends generally rectangular or race-track-shaped.

8. The orthodontic ligature of claim 1, having an overall outer shape in dimensions along the plane that is generally keyhole-shaped or oval.

9. The orthodontic ligature of claim 7, wherein the hole in dimensions along the plane is overall keyhole-shaped or oval, and wherein the overall outer shape of the orthodontic ligature forms a first center of area and the shape of the hole forms a second center of area, wherein the first and second center of area are offset from each other.

10. The orthodontic ligature of claim 1, being made of a thermoplastic elastomer.

11. An orthodontic ligature tree, comprising a bar at which a plurality of orthodontic ligatures according to claim 1 are arranged with the flaps oriented away from the bar, wherein the bar and the orthodontic ligatures are monolithically formed in one piece from the same material and being connected by a constricted link forming a pre-determined breaking zone.

12. The orthodontic ligature tree according to claim 11, wherein the plurality of orthodontic ligatures are arranged along two rows on opposite sides of the bar.

13. The orthodontic ligature tree according to claim 11, further comprising a finger ring which is connected to the bar.

14. A kit of parts, comprising the orthodontic ligature tree according to claim 11, and a set of patient-individual lingual brackets.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0020] FIG. 1 is a top view of an orthodontic ligature according to an embodiment of the invention; and

[0021] FIG. 2 is perspective view of an orthodontic ligature tree a according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 shows an orthodontic ligature 1. The orthodontic ligature 1 is adapted for securing an orthodontic archwire to an orthodontic bracket (not shown). In the example the orthodontic ligature 1 is illustrated at a stage at which it is relaxed, i.e. at a stage at which the orthodontic ligature 1 is not stretched or otherwise deformed by external forces.

[0023] The orthodontic ligature 1 is formed of a resilient band 12 which extends circumferentially along a non-circular closed path. In other words the resilient band 12 forms a closed non-circular ring. The Figure illustrates the closed path by the neutral axis 11. The neutral axis 11 for the purpose of the present specification is defined by the center areas of the cross-sections along which the resilient band extends. The resilient band 12 has a first section 13 and a second section 14, and the first and second section 13, 14 together form the orthodontic ligature 1. The first section 13 extends along a first partial length of the circumferential path. In the example the first section 13 extends at a generally uniform cross-section. Thus any stretching forces as they typically occur during use of the orthodontic ligature 1 in a patient's mouth are generally uniformly distributed within the first section 1. In the example the cross-section of the first section 13 is substantially rectangular, in particular rectangular which rounded corners. In another example the cross-section of the first section may be racing-track-shaped, meaning the outer shape of the cross-section may correspond to two spaced mirrored 180 degrees circular arcs of the same diameter which are connected by two parallel lines of the same length. In still further examples the cross-section of the first section may be circular or oval.

[0024] The resilient band in the second section 14 forms a flap 15. The flap 15 extends essentially parallel to the plane which the first section 13 extends along. The flap 15 forms a grip portion. Accordingly the flap 15 enables a user (for example an orthodontist during installing the orthodontic ligature 1 to a bracket) to grab the orthodontic ligature 1 at the flap 15 by help of tweezers. The flap 15 has a pair of retainers 16 which protrudes from the flap 15 in a dimension transverse to the dimension in which the flap 15 extends. The retainers 16 are spaced. The retainers 16 allow the tweezers to be positioned between, and thus to be positioned at a pre-determined position. This helps avoiding that the tweezers interfere with the bracket during installation of the orthodontic ligature 1 due to eventually malpositioned tweezers relative to the ligature 1. Further this helps avoiding that the flap 15 tears or slips out of the tweezers during installation of the orthodontic ligature 1. The pair of retainers 16 is preferably arranged on opposite sides of the flap 15.

[0025] The resilient band 12 further defines a non-circular hole 17. The resilient band 12 extends such that the hole 17 has a major dimension along a direction in which the flap 15 extends and is smaller in the dimension transverse thereto. In the example the hole 17 is elongated toward a direction in which the flap 15 extends. Thereby the dimensional change of the cross-section in the transition between the first and second section 13, 14 of the resilient band 12 is minimized. It has been found that this helps maximizing the durability of the ligature installed in a patient's mouth.

[0026] FIG. 2 shows an orthodontic ligature tree 100 having a plurality of orthodontic ligatures 1. The orthodontic ligature tree 100 has a bar 101 at which on opposite sides of the bar 101 orthodontic ligatures 1 are arranged in a straight row. The orthodontic ligatures 1 are arranged with the flaps 15 outwardly. Therefore each orthodontic ligature 1 can be easily grasped by a user between the retainers 16 at the flap 15 and can be used without repositioning or re-grasping. The orthodontic ligatures 1 are connected with the bar 101 by constricted links 102 which form a pre-determined breaking zone. Therefore the orthodontic ligatures 1 are enabled for separating from the bar by simply pulling them away from the bar 101 until the constricted link 102 breaks. The orthodontic ligature tree 100 further has a finger ring 103. The finger ring 103 facilitates handling of the orthodontic ligature tree 100, for example during separation of an orthodontic ligature 1 from the orthodontic ligature tree 100.

[0027] In the example the orthodontic ligature tree 100 is monolithically formed at least including the orthodontic ligatures 1, the bar 101, the constricted links 102 and the finger ring 103. Accordingly the orthodontic ligature tree 100 is made of one resilient material, in the example from a thermoplastic elastomer, in more particular from thermoplastic polyurethane, and preferably from Texin 285 as available from Bayer AG, Germany. Texin 285 is an aromatic polyester-based thermoplastic polyurethane grade with Shore A hardness of approximately 85.