WO2007088565A1

WO2007088565A1 - Orthodontic bracket and system

Info

Publication number: WO2007088565A1
Application number: PCT/IT2006/000624
Authority: WO
Inventors: Gabriele Scommegna; Maurizio Dolfi
Original assignee: Leone S.P.A.
Priority date: 2006-01-31
Filing date: 2006-08-22
Publication date: 2007-08-09
Also published as: ITFI20060029A1

Abstract

Orthodontic bracket, comprising a body (1) with a base (10) whose rear surface is intended to be applied onto a tooth (D) of a dental arch, said body (1) having, on the opposite side with respect to the base (10) , a plurality of wings (11, 110) between which a slot (12) for a preformed arch wire (2) is disposed, said wings (11, 110) projecting outwardly from the bracket and towards the base (10) and constituting anchoring elements for a ligature which prevents the wire (2) from disengaging the slot (12) . The upper or vestibular side (13) of the bracket is depressed with respect to the roots (14, 114) of said wings (11, 110) . (Fig.l) .

Description

TITLE

Orthodontic bracket and system. DESCRIPTION

The present invention relates to an orthodontic bracket and system.

It is known that, according procedures largely adopted in orthodontics, a plurality of brackets are bound on the vestibular side of the teeth of a dental arch. The brackets are provided with a transversal slot and are crossed by a suitably pre-shaped metal wire. The wire, thanks to its elastic properties, transmits to the teeth orthodontic forces whose intensity and direction determine moving of the teeth according to a preset scheme, in order to obtain a their rearrangement in conformity with a more correct functional, biological and esthetical configuration. A ligature device is applied onto each bracket to prevent the wire from disengaging the slot. Said device is made, in its simplest embodiment, by a ring of elastic material, i.e. polyurethane . Examples of orthodontic ligatures are disclosed in US 5540586, EP 289334, ES 1042372 and EP 1169977. Examples of orthodontic brackets are disclosed in EP 876801, US 5622494 and US 5326259. Usually, the time required for completing the orthodontic treatment and achieving the prefixed objective is excessive if compared with the patient's expectations and this is an obstacle for a wider use of orthodontics. Further obstacles for a wider use of orthodontics are the discomfort to which the patient is subjected during the treatment, the operative difficulties of the known orthodontic techniques, and, then, the need of highly specialized doctors. One of the aims of the present invention is to provide an orthodontic bracket allowing a drastic reduction of the time required to achieve the desired objective. Another aim of the invention is to provide an orthodontic bracket which, besides a reduction of the time required to complete the orthodontic treatment, is simpler to be manufactured and cheaper than the brackets of the known type.

Another aim of the invention is to provide an orthodontic system which, at * least for a determined type of clinic cases, allows procedural simplification during application of the ligatures and reduction of the orthodontic treatment time.

Moreover, another aim of the invention is to provide an orthodontic system which, at least in the less serious cases, eliminates the use of the traditional devices, allowing the increase of the dental arch perimeter, with the formation of a greater space to reduce the number of the possible necessary extractions .

This result has been achieved according to the invention thanks to the idea of actuating a system and making a device having the features described in the independent claims. Other features relate to the dependant claims .

Thanks to the present invention, it is possible to produce the same bracket for all the teeth, without differentiation of the shape and dimensions in relation with the specific tooth. Moreover, a bracket according to the invention can be produced, for example, in polycarbonate added with glass fibres, utilizing the injection moulding technique, thereby allowing further reduction of the production costs. Besides, a bracket according to the invention can be easily applied, even by not highly specialized doctors. Moreover, it is possible to utilize the same bracket during all the treatment, without the necessity of periodical substitution, and the application and the fixation o,f the ligature onto the bracket result highly improved. It is also possible to use a system of orthodontic brackets for obtaining an expansion effect involving the perimeter of the dental arch, usually obtained by means of devices like palatal screw expanders and similar, in combination and simultaneously with the orthodontic effect of teeth re-dislocation . It is also provided a fast effect of alignment and levelling of the teeth together with the increase of space in the dental arch.

These and other advantages and characteristics of the invention will be best understood by anyone skilled in the art from a reading of the .following description in v conjunction with the attached drawings given as a practical exemplification of the invention, but not to be considered in a limitative sense, wherein:

Fig.l shows a schematic side view of an orthodontic bracket according to the present invention;

Fig.2 shows a plan view of the bracket of Fig.l;

Figs.3-8 show, in perspective view, a sequence of steps relating to the positioning of a ligature on the bracket of Fig.l, applied onto the vestibular side of a tooth;

Figs .9 and 10 are two schemes showing a dental arch before and after a treatment executed according to the present invention;

Figs.11 and 12 are two schemes corresponding to those of Fig.9 and respectively Fig.10 in another representation plane.

Reduced to its basic structure and referring to the enclosed drawings, an orthodontic bracket according to the present invention is made by an element having a body (1) with a base (10) , the rear surface of which is to be applied onto a tooth (D) of a dental arch (i.e. onto the vestibular side of the tooth). Said body (1) has, on opposite side with respect to the base (10) , a plurality of wings (11, 110) , between which a slot (12) for receiving a preformed arch wire (2) is disposed along the mesio-distal direction. In practice, the slot (12) is in intermediate position between the wings (11, 110*) . Said wings project outwardly from the bracket and towards the base (10) and constitute anchoring elements for a ligature which prevents the wire (2) from disengaging the slot (12) . Said wings are three in the example shown by the enclosed drawings. Two wings (11) are on the same side of the slot (12) and are spaced from each other, the root of each of them being disposed at a corresponding end on the upper edge of the body (1) . The root of the third wing (110) extends in mesio-distal direction along all the corresponding upper edge of the body (D •

Said third wing (110) is provided with an appendix (111) which, according to the example shown in the enclosed drawings, extends the central part of the wing outwardly from the bracket. Said appendix (111) is, in the example, substantially triangular in plan, with two external concave sides (112) and a smoothed vertex (113) .

The upper or vestibular side (13) of the bracket is in depression in respect to the roots (14, 114) of said wings (11, 110) .

Moreover, advantageously, both the mesial and distal sides of the body (1) have channel-shaped depressions (15) starting from the roots (14, 114) of the wings (11, 110) and oriented parallel to the same. As shown in the enclosed drawings, the ligature device is an elastic "8"-shaped double ring, comprising a central body (30) and two rings (31, 310) which have oval shape when seen in plan view. Said two rings are disposed on opposite sides with respect to the central body (30) and are joined to the latter by the same moulding material of which the ligature device is made (for example polyurethane) . The length in mesio-distal direction of said central body (30) is smaller than the largest diameter of the two rings (31, 310) which, in turn, are identical to each other.

In the example, both the depression of the side (13) of the bracket and the central body (30) of the ligature are rectangular when seen in plan view. According to the present invention, it is possible to utilize brackets which are identical to each other, i.e. not differentiated in relation to the single tooth on which each bracket is to be applied. The archwire (2) can be a shape memory Nickel-Titanium alloy wire with round transverse section. The application of each bracket on the relevant tooth (D) is executed in a conventional manner, using adhesive substances known to the skilled in the dental art. In the enclosed drawings, the brackets are disposed in such a manner that the aforesaid appendix (111) of the wing (11) is turned toward the apical portion of the tooth.

Figs. 3-8 show schematically the application procedure of the ligatures: using a clamp (P), the doctor takes a ligature engaging one of the rings (31) and the central portion (30) . Then, u*sing the guide formed by the appendix (111) of the wing (110) , puts the other ring (310) on the same wings (110), as shown in Fig.3 and Fig.4. After, the doctor releases the ring (31) and, as shown in Fig.5, the ligature results firmly fixed to the bracket by means of the ring (310) fitted on the wing (110); this is possible thanks to the particular shape of the bracket which, also for the presence of the channels (15) , provides a firm temporary anchoring for the ligature. Afterwards, the doctor puts the wire (2) in the slot (12) and, as shown in Fig.6, exerts a light traction on the ring (31) by means of the clamp (P) , fitting the ring onto the wing (11) . The central body (30) of the ligature spontaneously places on the vestibular side (13) of the bracket, which is in depression between the roots of the wings (11, 110), whilΦ the mesial and distal portions of the rings (31, 310) are, at least partially, in the channel-shaped depressions (15) . Since the central body (30) of the ligature is disposed in the depression delimited by the roots of the wings (11, 110) on the vestibular side (13) of the bracket, and since the mesial and distal portions of the rings (31, 310) are at least partially disposed in the aforesaid channels (15) , the whole formed by the bracket and the ligature is more compact and, then, more comfortable, i.e. less irritating, for the patient, and it allows a more correct oral hygiene. The central body (30) of the ligature closes superiorly the slot (12) of t^he bracket substantially without contacting the wire (2), while the rings (31, 310) don't interact with the wire. In this way, the wire (2) is able to perform its function without substantial energy dissipation due to the friction with the material of the ligature, as, on the contrary, can occur when using conventional brackets and ligatures. This configuration, and the fact that cement used to fix the brackets onto the teeth is subject to a smaller stress when the ligature is applied, given the presence of the guide (111) which simplifies the positioning of the ligature onto each bracket, allows the achievement of the aforesaid advantages.

As schematically shown in Figs.9-12, the use of a device comprising a plurality of orthodontic brackets applied on the teeth of a whdle dental arch, engaged by a preformed metallic archwire and provided with respective low-friction ligatures, makes it also possible to obtain a remarkable increase of the dental arch perimeter together with the rearrangement or re- dislocation of the teeth, with an increase of the available space and a reduction of the possibly necessary extractions. Therefore, such device, which is realizable utilizing the aforesaid brackets, constitutes a device for the orthodontic correction and, at the same time, a dental-arch-expander exploitable in combined therapies having the aims of both the rearrangement of the teeth and the increase of the dental arch perimeter; -^thanks to this device it is possible to avoid the use of the conventional palate expanders, i.e. screw expanders, which are more invasive and involve a higher discomfort for the patient.

Experimental tests have demonstrated that the use of a system of the above described type allows to reduce of at least one half the period of the patient's treatment with respect to conventional devices. In practice, changes may be made to the form, dimensions, component part locations in the embodiment described and illustrated herein without, however, departing from the scope of the present invention.

Claims

1. Orthodontic bracket, comprising a body (1) with a base (10) whose rear surface is intended to be applied onto a tooth (D) of a dental arch, said body

(1) having, on the opposite side with respect to the base (10), a plurality of wings (11, 110) between which a slot (12) for a preformed arch wire (2) is disposed, said wings (11, 110) projecting outwardly from the bracket and . towards the base (10) and constituting anchoring elements for a ligature which prevents the wire (2) from disengaging the slot (12) , characterized in that the upper or vestibular side (13) of the bracket is depressed with respect to the roots (14, 114) of said wings (11, 110) .

2. Bracket according to claim 1, characterized in that the mesial and distal sides of the body (1) have channel-shaped depressions (15) starting from the roots (14, 114) of the wings (11, 110) .

3. Bracket according to claim 1, characterized in that said ligature device is an elastic "8"-shaped double ring, comprising a central body (30) and two oval- shaped rings (31, 310) disposed on opposite side in respect to the central body (30) and joined to the latter by the same moulding material of which the ligature device is made.

4. Bracket according to claim 3, characterized in that the length in mesio-distal direction of said central body (30) is smaller than the value of the largest diameter of the two rings (31, 310), the latter being identical to each other.

5. Bracket according to claim 1, characterized in that said depressed part is rectangular in plan.

6. Bracket according to claim 3, characterized in that said central body (30) is rectangular in plan.

7. Bracket according to claim 1, characterized in that one wing (110) is provided with an appendix (111) which extends the surface o\f the wing outwardly from the bracket.

8. Bracket according to claim 7, characterized in that said appendix (111) extends the central part of said wing (110) outwardly from the bracket.

9. Bracket according to claim 7, characterized in that said appendix (111) is substantially triangular in plan, with two concave external sides (112) and a smoothed vertex (113) .

10. Bracket according to claim 7, characterized in that said wings are in total three wings.

11. Bracket according to claim 10, characterized in that two wings (11) are on a same side with respect to the slot (12) and are separated form each other, the roots of each of them being disposed at a corresponding end on the upper edge of the body (1), the root of the third wing (110) extending in mesio- distal direction along all the corresponding upper edge of the body (1) .

12. Bracket according to claim 1, characterized in that said wire (2) is a shape memory Nickel-Titanium alloy wire having round transverse section.

13. System for obtaining an expansion of the dental arch perimeter together with a rearrangement of the teeth in a dental arch, characterized in that it comprises a plurality of orthodontic brackets engaged by a preformed metal arch wire, on each of said brackets being applied a low-friction ligature and each of said brackets being applied onto a correspondent tooth of the dental arch.

14. System according to claim 13, characterized in that said brackets are identical to each other.

15. System according to claim 13, characterized in that each bracket is made according to one or more of claims 1 to 12.