WO2012095681A1

WO2012095681A1 - Orthodontic bracket with removable cover and method for the assembly of said orthodontic bracket

Info

Publication number: WO2012095681A1
Application number: PCT/IB2011/000049
Authority: WO
Inventors: Valter Vigolo
Original assignee: Valter Vigolo
Priority date: 2011-01-14
Filing date: 2011-01-14
Publication date: 2012-07-19

Abstract

Orthodontic bracket (1) with removable cover (9), comprising a support body (2) with, formed therein, a slot (5) for insertion of an archwire able to impart a corrective action to a tooth and a hinging seat extending between two transverse guide faces along an axis of rotation Y1. The bracket also comprises a removable cover provided with at least one pin (10) able to be inserted in a removable manner coaxially inside the hinging seat (7) in order to connect rotatably the cover to the support body. The hinging seat is open towards the outside by means of a longitudinal slit which has a width smaller than the width of the hinging seat. The cover is provided with a shank having a width smaller than that of the pin and is able to slide in a coupling direction Y" parallel to the axis of rotation Y" with the shank arranged slidably inside the longitudinal slit and the pin arranged slidably inside the hinging seat, until a rotation position is reached, where the cover is rotatably coupled with the support body with the shank axially retained by the two guide faces of the support body in angular positions which are not aligned with the plane of insertion.

Description

ORTHODONTIC BRACKET WITH REMOVABLE COVER AND METHOD FOR THE ASSEMBLY OF SAID ORTHODONTIC BRACKET

DESCRIPTION

Field of application

The present invention relates to an orthodontic bracket with removable cover and to a method for the assembly of said orthodontic bracket.

The invention in question falls within the sector of orthodontics or that branch of dentistry which deals with the prevention and treatment of malocclusions.

Background art

It is known to treat malocclusions by means of orthodontic apparatus which are conventionally formed by a plurality of metal or ceramic attachments - commonly known by the term "brackets" - which are glued or cemented to the teeth for the duration of the period of treatment envisaged for the patient, and by at least one metal wire or "archwire", which is fastened to the brackets so as to act on the teeth with an action intended to displace the teeth also by large amounts, in all directions and with any type of movement, allowing correction of incorrectly positioned teeth which cannot be treated using other apparatus.

As is known, orthodontics, which makes use of fixed orthodontic apparatus, has developed its own different techniques which differ from each other mainly in terms of the position assumed by the apparatus inside the mouth, which may be vestibular or lingual, or in terms of the type of bracket used, which may be for example of the straight wire type, where the "information" for displacement of the teeth is provided by the shape of the slot, or of the tweed type, where the "information" for displacement of the teeth is mainly provided by the shape and arrangement of the archwire.

By means of the orthodontic apparatus three-dimensional control and differential movement of the position of the teeth is obtained, including principally the mesiodistal tip or angle of the crowns, the labio-lingual or vestibulo-lingual torque or inclination of the crowns, the rotation or in-out movement for defining, respectively, the correct orientation and the correct position of the teeth in the top and bottom dental arches.

Conventionally, a very common embodiment of bracket comprises a base provided with a support surface which is intended to adhere to a tooth and which has, extending therefrom, a support body (formed by one or more separate parts projecting from the base) provided with at least one through-seat (better known by the term "slot"), for insertion of a metallic archwire, and at least two or more lugs for retaining ligatures required to fix the archwire inside the slot. Disadvantageously, the ligatures produce friction with the archwire which prevents the latter from sliding freely and assisting a correct displacement of the teeth.

The ligatures which are mainly used are of the elastic or metallic type and have the drawback that they require laborious operations in order to fix them inside the patient's mouth, so that the duration of the necessary treatment sessions is very long and stressful for the patient.

Elastic ligatures moreover deteriorate very quickly, in particular if they are subject to high tensile forces, while metal ligatures, although withstanding high tensile forces require continuous adjustment when there is a variation in the position of the tooth in order to provide a uniform compressive action on the archwire.

In order to overcome the drawbacks encountered in the brackets of the known type described above and mainly associated with the limited practical nature of the archwire fixing system, more recently so-called "self-locking" orthodontic brackets have been developed, these envisaging the use of a cover which acts as a retaining element and which can be slidably or rotatably moved on the support body between a closed position, where it retains the archwire inside the slot, and an open position, where it releases the archwire from the slot.

In accordance with the embodiments described in the patents US 6071 1 19, US 5906486 and US 5586882, the cover slides inside a guide formed in the support body of the orthodontic bracket between the two aforementioned positions for retaining or releasing the archwire with respect to the slot.

In accordance with the embodiment illustrated for example in the patent US 5,857,849, the cover is rotatably connected to the support body and is movable between the two aforementioned positions, once again in order to retain or release the archwire with respect to the slot.

These solutions of the known type of bracket with covers movable between the two positions, although allowing a reduction in the bracket fitting time, have the drawback that they do not allow removal and replacement of the bracket with another bracket which has different technical or aesthetic characteristics.

There in fact exists the need to modify not only the retaining force exerted by the cover on the archwire cover - for example when it is required to vary the size of the archwire or modify the tensile force acting on the teeth during the course of treatment - but also the external appearance of the archwire using covers which have different colours or designs in particular in the case of young patients.

In order to meet these requirements, self-locking orthodontic brackets provided with a cover which can be removably connected to the support body have been introduced onto the market.

In accordance with the embodiments described in the patents US 7204691 , US 2010/129765 and US 4687441 the cover of the orthodontic bracket is removably mounted on the support body retaining elements by means of elastically deformable portions.

The cover, in accordance with the orthodontic brackets described in these patents, may be replaced, depending on the requirements of the orthodontic treatment in progress and depending on the aesthetic requirements of the patient (especially young patients), with another bracket having different technical and/or external characteristics.

The assembly of these covers, although simple compared to the assembly of conventional elastic ligatures, is not entirely easy, especially in view of the very small size of the brackets.

In order to overcome these latter drawbacks, recently orthodontic brackets have been developed, as described in the patents WO 0033760, US 2008/0241782 and WO 2008/025420, where said brackets are provided with a support body having, formed therein, the slot for inserting an archwire and a cover which is rotatably connected to the base and movable with respect thereto between a retaining position, where the cover is arranged to close the slot in order to retain the archwire inside it, and an open position where the cover is rotated angularly so as to release the archwire from the slot and allow insertion or removal thereof. Fastening means are provided for keeping the cover in the closed position, along with connecting means for allowing removably assembly of the cover on the support body. The fastening means are obtained by means of a front portion of the cover, which is elastically deformed when into comes into abutment against a corresponding portion of the support body, so as to snap-engage with a step-shaped head portion inside an undercut formed frontally on the support body.

The means for connecting the cover to the support body envisage the presence of one or two pins formed in the rear part of the cover and able to be inserted inside corresponding guides formed in the rear part of the support body. In accordance with the different embodiments described in the aforementioned patents WO 0033760, US 2008/0241782 and WO 2008/025420, the insertion of the pins of the cover inside the corresponding seats of the support body is performed by positioning the cover substantially aligned behind the base and then moving it towards the latter in order to obtain complete insertion of the pins inside the respective seats. At this point, a subsequent rotation of the cover with respect to the support body into the closed position allows the cover to be kept integrally fastened to the said support body.

In greater detail, with reference to the embodiments shown in Figures 1-3 in the patent WO 0033760, or the embodiments in Figures 7a, 7b, 7c of the patent US 6,964,565, or the embodiments in Figures l-5b of the patent US 2008/0241782 or the embodiments in Figures 5-9 of the patent WO 2008/025420, no twisting movement of the cover is envisaged in order to align it along the axis of rotation of the hinge or the guides of the support body, the cover being simply pushed by means of its pins inside the guides with a rectilinear movement.

Differently, with reference to the embodiments in Figures 6, 7 of the patent US 2008/0241782 or the embodiments in Figures 1-4 of the patent WO 2008/025420, or the embodiments in Figures 1-6E of the patent US 6,964,565, the cover is inserted, again from behind after being substantially aligned at the rear of the support body, but with a slight deformation of the pins obtained by compressing them inside the guides with a twisting movement which envisages positioning the cover so as to rest inclined on the support body with a first pin arranged in a first guide and then forcing the second pin inside the second guide by means of deformation of an elastically yielding portion of the support body defining the guide by means of an incision formed in the rear part of the said second guide. This incision is advantageously shaped in the manner of a ramp and therefore does not allow axial sliding of the cover.

With reference to this latter embodiment, it is envisaged that the procedure for extracting the cover is the reverse of the procedure for insertion (see in this connection, for example, on page 5, the start of paragraph [0056] in the patent US 2008/0241782) and, therefore, since the axial sliding extraction movement is prevented by the ramp-shaped deformable portion, the insertion procedure, being the same as the extraction procedure, does not induce the person skilled in the art to envisage axial sliding of the cover on the support body. Extraction of the cover is performed, in accordance with this embodiment, by means of twisting of the cover, forcing the pin situated opposite the incision to displace the elastically yielding portion of the support body and to come out of the incision.

The open position of the cover, for example shown in Figure 6B of the patent US 2008/0241782, with reference to which it is envisaged inserting and extracting the cover into/from the support body, would have further dissuaded the person skilled in the art from considering lateral insertion of the cover in view of the obvious interference which would occur during these operations between the cover and the said support structure. In the patent WO 2008/025420 it is further stated on page 1 1, paragraph 3, that the first embodiment explained above does not require, differently from the second embodiment, just considered, any twisting movement during alignment of the cover behind the support body, which twisting movement is therefore envisaged for this second embodiment, further dissuading the person skilled in the art from considering axial insertion of the cover inside the guides of the support body.

Still with reference to this embodiment the means for connecting the cover to the support body envisage the elastic deformation of an elastically yielding portion of the support body formed in the region of an incision in one of the two guides. In the event of breakage of this elastically yielding portion, during for example replacement of a cover with another cover possessing different features, it is disadvantageously required to detach the base from the tooth with an obvious increase, therefore, in the duration of the operations to be performed inside the patient's mouth.

Disclosure of the Invention

The problem forming the basis of the present invention is therefore to overcome the drawbacks associated with the aforementioned solutions of the known type, by providing an orthodontic bracket with removable cover and a method for the assembly of said orthodontic bracket, which allow simple and rapid replacement of the bracket cover with another cover having different technical or aesthetic features.

A further object of the present invention is to provide a bracket which is constructionally inexpensive to produce and simple to fit.

A further object of the present invention is to provide a method for the assembly of an orthodontic bracket which is simple and quick to produce and operationally entirely reliable.

Brief description of the drawings

The technical features of the invention, in accordance with the abovementioned objects, may be clearly determined from the contents of the claims below and the advantages thereof will emerge more clearly from the detailed description which follows, with reference to the accompanying drawings which illustrate a number of purely exemplary and non-limiting embodiments thereof, wherein:

- Figure 1 shows schematically a perspective top plan view of a first embodiment of an orthodontic bracket according to the invention with the cover in the open position and fully inserted inside the seat of the support body;

- Figure 2 shows a perspective side view of the orthodontic bracket according to Figure 1 with the cover in the open position and partially inserted inside the seat of the support body; - Figure 3 shows a perspective front view of the orthodontic bracket according to Figure 2 with the cover in the open position and partially inserted inside the seat of the support body;

- Figure 4 shows a perspective front view of the orthodontic bracket according to Figure 2 with the cover in the open position and fully extracted from the seat of the support body;

- Figure 5 shows a perspective top plan view of the orthodontic bracket according to Figure 1 with the cover mounted on the support body and in the closed position;

- Figure 6 shows schematically a perspective view of a second embodiment of an orthodontic bracket according to the invention with the cover and the support body shown in exploded form, i.e. separate from each other;

- Figure 7 shows a perspective top plan view of the orthodontic bracket according to Figure 6 with the cover in the open position and inserted inside the seat of the support body;

- Figure 8 shows a perspective top plan view of the orthodontic bracket according to Figure 6 with the cover mounted on the support body and in the closed position;

- Figure 9 shows schematically a perspective view of a third embodiment of an orthodontic bracket according to the invention with the cover in the open position and only partially inserted inside the seat of the support body;

- Figure 10 shows a perspective side view of the orthodontic bracket according to Figure 9 with the cover in the open position and fully inserted inside the seat of the support body;

- Figure 1 1 shows schematically a perspective view of a fourth embodiment of an orthodontic bracket according to the invention with the cover in the open position and only partially inserted inside the seat of the support body;

- Figure 12 shows a perspective side view of the orthodontic bracket according to Figure 1 1 with the cover in the open position and fully inserted inside the seat of the support body;

- Figure 13 shows a perspective front view of the orthodontic bracket according to Figure 1 1 with the cover mounted on the support body and in the closed position;

- Figures 14a, 14b and 14c show three different embodiments of orthodontic bracket covers according to the invention.

- Figure 15 shows a side view of an orthodontic bracket according to the invention with a cover according to Figures 14a, 14b and 14c mounted in the closed position;

- Figures 16a, 16b and 16c show three different embodiments of orthodontic bracket covers according to the invention;

- Figure 17 shows a side view of an orthodontic bracket according to the invention with a cover according to Figures 16a, 16b and 16c mounted in the closed position.

Detailed description

In accordance with the figures of the accompanying drawings, 1 denotes overall the orthodontic bracket with removable cover according to the present invention.

The orthodontic bracket 1 in question is intended to be used in a fixed apparatus for correction of misalignments of the top or bottom dental arches.

It is equally well designed, by making the usual modifications which are known to the person skilled in the art, for use both in vestibular apparatus and in lingual apparatus. Furthermore, it is possible to employ any orthodontic technique, be it for example of the straight wire type or tweed type, without thereby departing from the protective scope of the present invention.

With reference to the accompanying figures, the orthodontic bracket according to the present invention comprises conventionally a support body 2 provided with a base 3 having a support surface 4 intended to be fixed onto a tooth. This support surface 4 is preferably suitably treated for optimal retention on the tooth and, depending on the requirements, may have a flat or curved shape according to the tooth profile. It may also be fixed by means of direct attachment using glues or cements or may be fastened by means of orthodontic bands.

The support body 2 is passed through by a seat - known in the sector by the technical term "slot" and denoted by 5 in the accompanying figures - which extends substantially along a longitudinal seating direction Y and is able to receive inside it an archwire 6. The action of the latter on the slot 5 allows corrective action on the tooth or the three- dimensional control and the differential movement of the position of the tooth.

The archwire 6 may for example consist of a wire made of nickel-titanium, nickel- titanium copper, medical steel or other material, may be formed as a single wire or as several braided wires, may be modelled with a finish and external appearance which can be varied depending on the specific applicational requirements (for example the cross- section may be square, rectangular, circular or D-shaped), may have so-called superelastic properties or an elasticity dependent on the temperature, or may be rigid, or may be used both torqued and non-torqued.

The accompanying figures show the orthodontic bracket 1 according to the invention in an entirely schematic form, it being understood that the forms and surfaces may vary in order to take into account in particular, in a manner known per se, the interaction with the gums and with the tongue or the requirement to provide buttons or hooks for the engagement of elastic elements, springs or other devices of the type known per se.

Each bracket may be made of metal (such as steel, titanium or nickel-titanium alloys) using the technique known as "metal injection moulding" or by means of stock removal using numerical control machines, or of ceramics using the technique called "ceramic injection moulding", or polycarbonate and steel for usually aesthetic reasons, or also a polymer resin or a vitreous material.

The support body 2 may be shaped as a single body which extends projecting from its base 3 or in the form of several bodies which extend from the base so as to shape the parts specified below.

In greater detail, the support body is provided with a hinging seat 7, which extends along an axis of rotation Y', substantially parallel to the direction of longitudinal extension of the bracket or the direction Y of the slot 5 when the latter is not inclined in order to impart a tipping movement to the tooth.

The aforementioned seat 7 is bounded by two transverse guide faces 8, 8' which, depending on the embodiment shown in Figures 1-8 or 9-10, shall be directed facing each other or directed in opposite directions.

The orthodontic bracket 1 is also composed of a cover 9 provided with at least one pin 10 able to be inserted removably and coaxially inside the aforementioned hinging seat 7 so as to connect rotatably the cover to the support body 2 about the axis of rotation Y'.

According to the underlying idea of the present invention the hinging seat 7 is open outwards (towards the rear part 1 1 of the support body 2) by means of a longitudinal slit 12, which extends parallel to the axis of rotation Y' of the hinging seat 7 and has a width d smaller than the width D of the latter.

The cover 9 is provided with a shank 13 having a width 1 less than the width L of the pin 10 and is able to slide in a coupling direction Y" parallel to the axis of rotation Y' lying in a plane of insertion determined by the position of the shank 13 inside the longitudinal slit 12 and by the position of the pin 10 inside the hinging seat 7 until an axial position of rotation R is reached. In this axial position of rotation R, the cover 9 is rotatably coupled with the support body 2 with the shank 13 which is axially retained by the two transverse guide faces 8, 8' of the support body 2 in all those angular positions of the cover 9 which are not aligned with the aforementioned insertion plane.

Still in this axial position of rotation R, the cover 9 is able to be rotatably displaced on the support body 2 between an open position A, where it frees the archwire 6 from the slot 5, and a closed position B, where it retains the archwire 6 inside the slot 5.

Preferably, the aforementioned longitudinal slit 12 extends over the entire length of the hinging seat 7 and is open towards a rear part 1 1 of the support body 2 of the orthodontic bracket 1.

According to an advantageous characteristic feature of the orthodontic bracket 1 according to the present invention, a projecting element 14 is arranged outside the seat of the hinge 7 and the slit 12, on the cover 9, in accordance with the embodiments shown in Figures 6, 7, 8, 9 and 10, or on the support body 2, in accordance with the embodiments shown in Figures 1, 2, 3, 4, 5, 1 1 , 12, 13.

The projecting element 14 is advantageously provided with two ramps 14', 14" sloping in opposite directions, aligned with the directions of insertion and extraction of the coupling movement Y" of the cover 9.

Operationally speaking, this projecting element 14 causes an interfering engagement, respectively, with the support body 2, in the case of the embodiments shown in Figures 6, 7, 8, 9 and 10, or with the cover 9, in the case of the embodiments shown in Figures 1, 2, 3, 4, 5, 1 1, 12 and 13. The presence of said projecting element in fact produces forced disengagement and engagement of the cover 9 with respect to the support body 2 owing to the elastic deformation affecting the cover 9 as a result of sliding, in the two directions of insertion and extraction of the said cover 9 into/from the support body 2, and, more precisely, sliding of the pin 10 inside the hinging seat 7 and the shank 13 inside the longitudinal slit 12.

Preferably, the projecting element 14 is provided in a positioned unaligned with respect to the seat 7 and the slit 12 so as to produce, by means of the aforementioned interfering engagement, a flexing moment designed to raise elastically the cover 9 away from the top face of the support body 2. The unaligned position of the projecting element 14 with respect to the hinging seat 7 and the longitudinal slit 12 for sliding of the cover 9 produces a flexing moment on the cover 9, tending to raise it so that the said cover 9 is able to easily overcome the projecting element 14.

Advantageously, the cover 9, during its insertion and extraction movement, before encountering the corresponding ramp 14', 14" of the projecting element 14, engages with its shank 13 inside the longitudinal slit 12 of the support body 2, so as to prevent the cover 9 from rotating with the pin 10 inside the seat 7 about the axis of rotation Y following the flexing moment produced by the interference of the cover 9 with the said projecting element 14. For this purpose, the ramps 14, 14' have a length which overall is shorter than the longitudinal slit 12.

The raising action exerted by the projecting element 14 may thus be easily supplemented by a manual action on the part of the operator which may in fact force the cover 9 away from the support body 9 namely beyond the open position A in order to allow the cover 9 itself to overcome, during its axial sliding movement, the interference produced by the projecting element 14.

In accordance with the embodiments shown in Figures 1 , 2, 3, 4, 5, 1 1, 12, 13 the projecting element 14 is formed on the support body 2 in the vicinity of its rear portion 1 1 and therefore of the aforementioned hinging seat 7. It interferes with a rear portion 9' of the cover 9 and preferably with its shank 13 following sliding of the pin 10 inside the hinging seat 7 and the shank 13 inside the longitudinal slit 12 in the two directions of insertion and extraction of the cover 9.

In accordance with the embodiments shown in Figures 6, 7, 8, 9 and 10 the projecting element 14 is formed on the cover 9, in particular in the vicinity of the rear portion 9' of the cover 9 and preferably in the region of its shank 13, and interferes with the rear part 1 1 of the support body 2 following sliding of the pin 10 inside the hinging seat 7 and the shank 13 inside the longitudinal slit 12 in the two directions of insertion and extraction of the cover 9.

In accordance with the embodiment shown in Figures 1 -8 the shank 13 is shaped in the form of a fork with two lateral support arms 15, 16 which define a first opening 17 situated centrally. In greater detail, the two arms 15, 16 are connected at one end to the pin 10 (which may be in the form of one piece or several axially aligned segments) and at the other end to a locking portion of the cover 9 intended to retain the archwire inside the slot 5, when the cover 9 is in the closed position B.

The support body 2 is provided with a central portion 18 which has, formed therein, the aforementioned hinging seat 7 and longitudinal slit 12 and defines laterally the two transverse guide faces 8, 8'.

The aforementioned central portion 18 of the support body 2 is inserted inside the first opening 17 of the arms 15, 16 of the fork so as to guide the shank 13 of the cover 9 by means of its said two transverse guide faces 8, 8' when the cover 9 is arranged in the axial position of rotation R.

In accordance with the embodiment shown in Figures 9-13 the support body is provided with two shoulders 19, 20 which are separated from each other along the axis of rotation Y' and are substantially arranged along the two lateral flanks of the orthodontic bracket 1. The aforementioned two shoulders 19, 20 define with their opposite inner surfaces the transverse guide faces 8, 8' between which the shank 13 of the cover 9 is received in a guided manner when the said cover is positioned in the aforementioned axial position of rotation R.

Preferably, in accordance with all the embodiments indicated above, an end-of-travel stop is defined during opening by the abutment between the portion 21 of the cover 9 and a corresponding portion 22 - making contact (during rotation) - of the support body 2. In the case of the example shown in Figures 1-5 and 9-13 the portion 21 of the cover 9 and the contact portion 22 of the support body 2 are simply formed by means of a folded rear end portion (with an advantageously right-angled fold) of the shank 13 (or, more specifically, of the two arms 15 and 16 of the shank as indicated below) and a top surface of the base 3 of the support body 2.

In the case of the example shown in Figures 6-8 the portion 21 of the cover 9 and the contact portion 22 of the support body 2 are formed by means of a rear edge of the first opening 17 of the cover 9 and a stud projecting at the rear from the support body 2.

This end-of-travel stop is advantageously located at the point where the cover 9 is situated along the lie of the insertion plane defined by the position of the shank 13 inside the longitudinal slit 12 and by the position of the pin 10 inside the hinging seat 7.

Advantageously, this end-of-travel stop may be used for leverage of the cover 9 so as to raise it manually above the projecting element 14, forcing it to rotate beyond the open position A, even before displacing it axially.

In accordance with a further advantageous characteristic feature of the orthodontic bracket 1 according to the invention, the support body 2 is provided with a second seat 7' which is formed on its front part 23 and which, together with the hinging seat 7 formed in the rear part 1 1 and intended to receive the pin 10 of the cover 9, defines the cavities for fastening the ligatures for retaining the archwire 6 when the cover 9 is separated from the support body 2.

Owing to this feature, the support body 2 of the bracket 1 may act, in the absence of the cover 9, as an orthodontic bracket itself, namely no longer as a self-ligating bracket, as in the case of the examples cited above, but as a bracket with normal ligatures allowing the bracket 1 according to the present invention to have a greater versatility of use compared to the brackets of the known type.

The second seat 7' may be formed by means of cavities formed in the front part 23 of the support body 2 or, preferably, in accordance with the examples of the accompanying figures, by means of a nose 24 projecting from the front part 23 of the support body 2 and defining a step below which the abovementioned second seat T is defined.

Retaining means are envisaged for closing the cover 9 in the closed position B of the slot

5 so as to lock the archwire 6 inside the said slot 5.

These retaining means comprise at least one first element 25, which is provided on the cover 9, and at least one second element 26, which is provided on the support body 2, said elements being able to be engaged together by means of elastic deformation of at least one of them in the closed position of the cover 9.

Figures 14a, 14b, 14c and 16a, 16b, 16c show three different embodiments of these retaining means. The person skilled in the art may obviously envisage other embodiments which are entirely equivalent to those shown without thereby departing from the scope of protection of the present invention.

The locking portion of the cover 9 is provided on its bottom face directed towards the support body 2 with a lug 27 intended to be inserted, at least partially, to a given depth inside the slot 5 seating the archwire 6 so as to retain the latter on top or impart thereto the desired mechanical stress.

The cover 9, or at least its top face, is able to carry ornaments formed, for example, with different colours or figures which may be chosen by the patient depending on the desired external features and which may be varied by simply replacing the cover 9 with another cover which has different external features.

The replacement of the cover 9 may also satisfy the technical requirements of varying the pressure applied to the archwire 6 by covers 9 which are differently formed or intended to compensate in a varying manner for the space formed inside the slot 5 by different archwires 6 of varying thickness to be used during the course of treatment.

The present invention also relates to a method for the assembly of an orthodontic bracket 1 which, in particular, but not exclusively, is intended to be implemented in combination with the bracket 1 described above and for which the same reference numbers will be maintained for the sake of simplicity of the description.

This method envisages preliminarily a step for aligning the cover 9 along the plane of insertion defined by the position of the shank 13 aligned with the longitudinal slit 12 and by the position of the pin 10 aligned with the hinging seat 7.

The cover 9 is then coupled with the support body 2 by means of insertion of the shank 13 inside the longitudinal slit 12 and the pin 10 inside the hinging seat 7, until the axial position of rotation R of the cover 9 is reached where the latter is rotatably coupled with the support body 2 with its shank 13 which is axially retained by the two guide faces 8, 8' of the support body 2 in angular positions which are not aligned with the plane of insertion.

In accordance with an important characteristic feature of the invention, during insertion of the cover 9 into the support body 2 (and similarly, mutatis mutandis, during extraction), axial forcing of the cover 9 occurs, by means of which said cover is elastically deformed so as to overcome the interfering engagement resulting from contact between the projecting element 14, provided no the outside of the hinging seat 7 and the longitudinal slit 12, and the cover 9 or the support body 2, depending on where the said projecting element 14 is located in accordance with the different embodiments illustrated above.

Advantageously, the elastic deformation of the cover 9, in order to overcome the interfering engagement resulting from contact with the projecting element 14, is obtained by forcing rotationally the cover 9 beyond the open position A and elastically deforming the cover 9 so as to overcome the projecting element 14 by means of a subsequent displacement in the direction of insertion of the coupling movement Y".

So that the flexing moment produced by contact with the projecting element 14 during axial displacement of the cover 9 does not result in a simple rotation of the cover with its pin 10 about the rotational axis Y', during insertion and extraction into/from the support body 2, the cover 9 engages with its shank 13 inside the longitudinal slit 12 before interfering with the projecting element 14. In this way, the cover 9, pushed upwards into a position where it is not aligned with the seat 7 and the slit 12 by the interference with the projecting element 14, is raised beyond the projecting element 14 by means of leverage on the edge of the slit 12 so as to overcome the said projecting element 14 during its insertion or extraction movement.

The invention thus conceived therefore achieves the predefined objects.

Obviously, it may assume, during its practical realization, also forms and configurations different from that illustrated above, without thereby departing from the present scope of protection. Moreover, all the details may be replaced by technically equivalent elements and the forms, dimensions, and materials used may be of any nature according to requirements.

Claims

1. Orthodontic bracket with removable cover, comprising:

- a support body having:

- a support surface intended to be fixed onto a tooth;

- a slot extending in a longitudinal direction Y and able to receive inside it an archwire capable of imparting a corrective action to said tooth;

- a hinging seat extending along an axis of rotation Y';

- a cover with at least one pin able to be inserted in a removable manner coaxially inside said hinging seat in order to connect rotatably said cover to said support body about said axis of rotation Y';

characterized in that

- said hinging seat is open towards the outside by means of at least one longitudinal slit which extends parallel to said hinging seat and has a width smaller than the latter;

- said cover has at least one shank with a width smaller than said pin and is able to slide, in a coupling direction Y" parallel to said axis of rotation Y' lying in a plane of insertion defined by the position of said shank inside said longitudinal slit and by the position of said pin inside said hinging seat, as far as a rotation position, where said cover is rotatably coupled with said support body with said shank axially retained by the two guide faces of said support body in angular positions which are not aligned with said insertion plane.

2. Orthodontic bracket according to Claim 1 , characterized in that said slit extends along the entire length of said hinging seat towards a rear part of the support body of said bracket.

3. Orthodontic bracket according to Claim 1 , characterized in that it comprises a projecting element which is arranged on the outside of said hinging seat and said slit on said cover or on said support body, provided with ramps sloping in opposite directions of insertion and extraction of said coupling movement and able to produce an interfering engagement with said support body or with said cover, respectively, causing forced engagement and disengagement of said cover with/from said support body following elastic deformation of said cover as a result of sliding, in the two directions of insertion and extraction, of said cover with said pin inside said hinging seat and with said shank inside said slit.

4. Orthodontic bracket according to Claim 3, characterized in that said projecting element is provided in a position unaligned with respect to said shank so as to produce, by means of said interfering engagement, a flexing moment designed to raise elastically said cover.

5. Orthodontic bracket according to Claim 3, characterized in that said projecting element is formed on said support body, in particular in the vicinity of said hinging, seat, and interferes with a rear portion of said cover as a result of sliding, in the two directions of insertion and extraction, of said cover with said pin inside said hinging seat and with said shank inside slit.

6. Orthodontic bracket according to Claim 3, characterized in that said projecting element is formed on said cover, in particular in the vicinity of said shank, and interferes with a rear part of said support body as a result of sliding, in the two directions of insertion and extraction, of said cover with said pin inside said hinging seat and with said shank inside said slit.

7. Orthodontic bracket according to any one of the preceding claims, characterized n that said projecting element is provided in a position unaligned with respect to said shank so as to produce by means of said interfering engagement a flexing moment intended to raise elastically said cover.

8. Orthodontic bracket according to any one of the preceding claims, characterized in that said shank is shaped in the form of a fork with two lateral support arms, which define a first opening and are connected at one end to said at least one pin and at the other end to a locking portion of said cover, intended to retain said archwire inside said slot when the cover is in said closed position;

said support body is provided with a central portion which has, formed therein, said hinging seat and said slit, defines laterally said two transverse guide faces and is able to be inserted inside the first opening of the arms of said fork so as to guide said shank with said two transverse guide faces when said shank is in said rotation position.

9. Orthodontic bracket according to any one of the preceding claims, characterized in that it comprises an end-of-travel stop during opening, provided by the abutment between a portion of said cover and a corresponding contact portion of said support body.

10. Orthodontic bracket according to Claim 9, characterized in that said cover is able to be disengaged from said support body, forcing it to rotate beyond said open position so as to deform elastically said cover and overcome said projecting element by means of a subsequent displacement along the extraction direction of said coupling movement.

1 1. Orthodontic bracket according to Claim 1 , characterized in that said support body is provided with at least two shoulders which are separate from each other along said axis of rotation and which define with their inner surfaces the transverse guide faces between which the shank of said cover is arranged in a guided manner in said rotation position.

12. Orthodontic bracket according to Claim 1 , characterized in that it comprises at least one second seat which is formed in the front part of the support body and which, together with the hinging seat intended to receive said at least one pin of the cover, defines the fastening cavity for ligatures for retaining the archwire when said cover is separated from said support body.

13. Orthodontic bracket according to Claim 1, characterized in that it comprises retaining means comprising at least one first element provided on said cover and at least one second element provided on said support body, said elements being able to be mutually engaged together by means of elastic deformation of at least one of them in the closed position of said cover.

14. Method for the assembly of an orthodontic bracket according to Claim 1 , which comprises the following operating steps:

- alignment of said cover along said plane of insertion defined by the position of said shank aligned with said longitudinal slit and by the position of said pin aligned with said hinging seat;

- coupling of said cover with said support body, with said cover in said plane of alignment by means of insertion of said shank inside said longitudinal slit and said pin inside said hinging seat, until the axial position of rotation of said cover is reached, where said cover is rotatably coupled with said support body with said shank axially retained by the two guide faces of said support body in angular positions which are not aligned¹ with said plane of insertion.

15. Method for the assembly of an orthodontic bracket according to Claims 3 and 14, wherein, during said insertion, axial forcing of said cover occurs, by means of which said cover is deformed elastically so as to overcome the interfering engagement produced by the contact between the projecting element provided on the outside of said hinging seat and said slit and said cover or said support body.

16. Method for assembly of an orthodontic bracket according to Claims 9 and 15, wherein the elastic deformation of said cover in order to overcome the interfering engagement produced by the contact with said projecting element is obtained by rotationally forcing said cover beyond said open position and thereby deforming elastically said cover so as to overcome said projecting element by means of a subsequent displacement along the insertion direction of said coupling movement.

17. Method for the assembly of an orthodontic bracket according to Claim 15, wherein said cover, during insertion and extraction into/from said support body, engages with its shank inside said longitudinal slit before interfering with said projecting element.