ORTHODONTIC DEVICE AND ORTHODONTIC KIT FOR TREATING MALOCCLUSIONS

Abstract

Orthodontic device for treating malocclusions, comprising a support body, fixable to a first tooth and on which a housing seat is made, and a spacer bar, placed to connect between the support body and a second tooth.

The spacer bar comprises a hinging portion, rotatably connected to said support body around a rotation axis, an elongated central portion and an end portion, extended starting from the central portion in an opposite position with respect to the hinging portion and fixable to the second tooth. In particular, the hinging portion of the spacer bar comprises two opposite planar surfaces, substantially perpendicular with respect to the rotation axis, and a lateral surface, placed to connect the planar surfaces and with at least partially cylindrical shape.

In addition, the housing seat of the support body is at least partially counter-shaped with respect to the hinging portion.

Claims

1. An orthodontic device for treating malocclusions, which comprises: a support body (2), which comprises an attachment base (20) intended to be fixed to a first tooth (D1) and on which a housing seat (21) is made; a spacer bar (3), intended to be placed to connect between the support body (2) and a second tooth (D2); said spacer bar (3) comprises: a hinging portion (31), rotatably connected to said support body (2) around a rotation axis (R) and at least partially inserted within the housing seat (21) of said support body (2); an elongated central portion (32), mainly extended along an extension direction (D) starting from said hinging portion (31); an end portion (33), extended starting from said central portion (32) in a position opposite said hinging portion (31) and intended to be fixed to the second tooth (D2); wherein the hinging portion (31) of said spacer bar (3) comprises: two opposite planar surfaces (34), substantially perpendicular with respect to the rotation axis (R); a lateral surface (35), placed to connect the planar surfaces (34); wherein the lateral surface (35) of said hinging portion (31) has at least partially cylindrical shape; and wherein the housing seat (21) of said support body (2) is at least partially counter-shaped with respect to said hinging portion (31) and substantially to size.

2. The orthodontic device according to claim 1, wherein said hinging portion (31) forms, with said housing seat (21), a revolute joint around said rotation axis (R).

3. The orthodontic device according to claim 1, wherein said housing seat (21) is internally delimited at least by two abutment surfaces (23), planar and opposite, which face the planar surfaces (34) of said hinging portion (31) and are configured for preventing the rotation of said hinging portion (31) around an axis different from said rotation axis (R).

4. The orthodontic device according to claim 3, wherein said housing seat (21) is internally delimited at least by a slide surface (24), at least partially cylindrical, which is placed to connect between said abutment surfaces (23) and faces the lateral surface (35) of said hinging portion (31).

5. The orthodontic device according to claim 3, wherein the planar surfaces (34) of said hinging portion (31) are placed substantially in contact with or in abutment against the aforesaid abutment surfaces (23).

6. The orthodontic device according to claim 3, wherein the distance between the abutment surfaces (23) of said housing seat (21) is substantially equal to the distance between the planar surfaces (34) of said hinging portion (31).

7. The orthodontic device according to claim 1, wherein said support body (2) comprises an access mouth (22) starting from which said housing seat (21) is extended, said access mouth (22) having size equal to or greater than the hinging portion (31) of said spacer bar (3) in order to allow the passage of said hinging portion (31).

8. The orthodontic device according to claim 7, wherein said hinging portion (31) comprises a closure surface (36), which is connected with the lateral surface (35) by a peripheral edge (37), wherein said hinging portion (31) is placed in said housing seat (21) in at least one operating position in which: the peripheral edge (37) of said closure surface (36) is placed at said access mouth (22), or the peripheral edge (37) of said closure surface (36) is placed within said housing seat (21).

9. The orthodontic device according to claim 1, wherein said end portion (33) comprises at least one hook (38) intended to be associated with an elastic tensioning element.

10. The orthodontic device according to claim 9, wherein said end portion (33) comprises an end edge (39) opposite said hinging portion (31), wherein said hook (38) is extended along said extension direction (D) starting from said end edge (39).

11. The orthodontic device according to claim 9, further comprising two of said hooks (38).

12. The orthodontic device according to claim 1, wherein said support body (2) comprises at least one occlusogingival marking line (25) parallel to said rotation axis (R).

13. The orthodontic device according to claim 1, wherein said support body (2) comprises at least one mesiodistal marking line (25) parallel to said extension direction (D).

14. An orthodontic kit for treating malocclusions comprising at least one support body (2) and a plurality of spacer bars (3) of the orthodontic device (1) according to claim 1.

15. The orthodontic kit according to claim 14, wherein each of said spacer bars (3) is provided with an elongated central portion (32) with length different from that of the other said spacer bars (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The technical characteristics of the invention, according to the aforesaid objects, are clearly seen in the contents of the below-reported claims and the advantages thereof will be more evident from the following detailed description, made with reference to the enclosed drawings, which represent several merely exemplifying and non-limiting embodiments of the invention, in which:

[0032] FIG. 1 shows a top view of an orthodontic device in accordance with the preferred embodiment of the invention with a support body and a spacer bar that are disassembled;

[0033] FIGS. 2a and 2b respectively show a side view of a first embodiment variant and of a second embodiment variant of the spacer bar of the device of FIG. 1;

[0034] FIGS. 3a and 3b show a top view of the hinging portion of the spacer bar respectively in accordance with the first and the second embodiment variant;

[0035] FIGS. 4a and 4b show a vertical section view of a detail of the device of FIG. 1, respectively in accordance with the first and the second embodiment variant of the spacer bar;

[0036] FIGS. 5a and 5b show a bottom horizontal section view of a detail of the device of FIG. 1, respectively in accordance with the first and the second embodiment variant of the spacer bar;

[0037] FIG. 6 shows a view of the attachment body of the device of FIG. 1 from the side of the access mouth of the housing seat;

[0038] FIG. 7 shows a top view of a detail relative to the support body and to a hinging portion of the spacer bar of the assembled device of FIG. 1;

[0039] FIG. 8 shows a vertical section view of the attachment body of FIG. 6;

[0040] FIG. 9 shows a side view of the detail of FIG. 7;

[0041] FIG. 10 shows a detail of a spacer bar provided with two hooks in accordance with a further embodiment of the device;

[0042] FIG. 11 shows a schematic view of the device of FIG. 1 applied to the mouth of a patient, which shows the force generated by an elastic pulling element;

[0043] FIG. 12 shows a schematic view of the device of FIG. 10 applied to the mouth of a patient, which shows the forces generated by elastic pulling elements.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0044] With reference to the enclosed drawings, reference number 1 overall indicates the orthodontic device for treating malocclusions, object of the invention.

[0045] The device 1, object of the invention, is advantageously intended to be employed in the field of orthodontics for treating dental malocclusions, in particular in the mandibular skeletal correction so as to remedy Class II malocclusions, and advantageously also Class III malocclusions, of a patient and to obtain a correct ratio between the teeth of the maxilla and the teeth of the mandible. For such purpose, the device 1 is advantageously intended to be fixed to a first tooth D1, in particular a molar of a semi-upper arch of the mouth of a patient in the case of treatment of Class II malocclusion, and advantageously to a second tooth D2, in particular a canine of the same semi-arch.

[0046] Hereinbelow, the use examples will be referred to the treatment of Class II malocclusion. Of course, without departing from the protective scope of the present invention, the orthodontic device 1 can also be used for treating the Class III malocclusion, for example by applying it to the lower arch, in a manner opposite that described herein.

[0047] In accordance with the invention, the device 1 is provided with a support body 2, which comprises an attachment base 20 intended to be fixed to the first tooth D1 and on which a housing seat 21 is made.

[0048] In addition, the device 1 is provided with a spacer bar 3, intended to be placed to connect between the support body 2 and the second tooth D2. In particular, the spacer bar 3 is rotatably connected to the aforesaid support body 2.

[0049] More in detail, the spacer bar 3 comprises a hinging portion 31, rotatably connected to the support body 2 around a rotation axis R, preferably occlusogingival. In addition, the hinging portion 31 is at least partially inserted within the housing seat 21 of the support body 2.

[0050] More in detail, the hinging portion 31 of the spacer bar 3 comprises two opposite planar surfaces 34, substantially perpendicular to the rotation axis R and a lateral surface 35, placed to connect the planar surfaces 34.

[0051] Of course, it is intended that possibly the planar surfaces 34 can be connected to the lateral surface 35 by curved connector surfaces.

[0052] The spacer bar 3 also comprises an elongated central portion 32 mainly extended along an extension direction D, preferably mesiodistal, starting from said hinging portion 31. Preferably, the central portion 32 has curved shape.

[0053] In addition, the spacer bar 3 comprises an end portion 33, extended starting from the central portion 32 in opposite position with respect to the hinging portion 31 and intended to be fixed to the second tooth D2. Advantageously, the end portion 33 has elongated shape so as to increase the fixing area to the second tooth D2.

[0054] In accordance with the idea underlying present invention, the lateral surface 35 of the hinging portion 31 has at least partially cylindrical shape.

[0055] In addition, the housing seat 21 of the support body 2 is at least partially counter-shaped with respect to the hinging portion 31 and preferably substantially to size. In particular, the housing seat 21 is shaped such to substantially entirely prevent the rotation of the hinging portion 31 around any axis different from the rotation axis R.

[0056] In this manner, the rotation of the hinging portion 31 around an axis different from the rotation axis R, for example around a labial axis, perpendicular to the tooth, remains zero or very small, since it is limited by the interference of the hinging portion 31 with the housing seat 21 partially counter-shaped thereto and preferably substantially to size.

[0057] In other words, advantageously, the hinging portion 31 forms, with the housing seat 21, a revolute joint around the rotation axis R. In particular, such revolute joint prevents any rotation of the spacer bar 3 with respect to the support body 2 except for the rotation around the rotation axis R, which is permitted.

[0058] In accordance with the preferred embodiment, illustrated in the enclosed FIGS. 6, 7, 8 and 9, the housing seat 21 is internally delimited at least by two abutment surfaces 23, planar and opposite, which face the planar surfaces 34 of the hinging portion 31 and are configured for preventing the rotation of the hinging portion 31 around an axis different from the rotation axis R. In particular, the planar surfaces 34 of the hinging portion 31 are placed substantially in contact with or in abutment against the aforesaid abutment surfaces 23.

[0059] For such purpose, advantageously, the distance between the abutment surfaces 23 of the housing seat 21 is substantially equal to the distance between the planar surfaces 34 of the hinging portion 31, i.e. in particular to the length of the hinging portion 31 along the rotation axis R.

[0060] Of course, such distances are to be considered net of a minimum clearance dictated by the processing tolerances, and by the need to allow the insertion of the hinging portion 31 in the housing seat 21. For example, such clearance (if present) can at most allow a minimum rotation of the spacer bar 3 in occlusogingival direction and/or around a mesiodistal axis by an angle with width smaller than 20?, preferably with width smaller than 15? and still more preferably with width smaller than 10?.

[0061] Advantageously, the housing seat 21 is also internally delimited at least by a slide surface 24, at least partially cylindrical, which is placed to connect between the abutment surfaces 23 and faces the lateral surface 35 of the hinging portion 31. Preferably, the lateral surface 35 of the hinging portion 31 is placed in contact with the slide surface 24 and is adapted to slide on the latter in the rotation around the rotation axis R.

[0062] In this manner, the rotation of the hinging portion 31 around an axis different from the rotation axis R, e.g. around a labial axis, is advantageously limited first of all by the abutment between the planar surfaces 34 and the abutment surfaces 23 and secondly by the contact of the lateral surface 35 with the abutment surface 23.

[0063] Advantageously, the elimination or minimization of the possibility of rotating around an axis different from the rotation axis R allows distributing any occlusogingival component of a force F applied to the spacer bar 3 in a uniform manner both to the first tooth D1 and to the second tooth D2. In the event in which the second tooth D2 is an upper canine, this factor thus allows considerably reducing the risk of extrusion, since the forces are distributed in an equal manner between the latter and the upper molar. For the same reason, also the risk of torque of the canine is advantageously reduced.

[0064] At the same time, the device 1 advantageously and more stably connects the first tooth D1 and the second tooth D2 and consequently allows the uniform treatment of the dental arch part comprised therebetween.

[0065] Advantageously, the support body 2 comprises an access mouth 22 starting from which the housing seat 21 is extended. In particular, the access mouth 22 has size equal to or greater than the hinging portion 31 of the spacer bar 3 in order to allow the passage of the hinging portion 31 itself.

[0066] In particular, the size of the access mouth 22 is such to freely allow the insertion and the removal of the hinging portion 31 within the housing seat 21. Therefore, when the device 1 is not fixed to the suitable dental arch, the support body 2 and the spacer bar 3 are advantageously removably connected to each other.

[0067] In this manner, it is possible to mount the spacer bar 3, by associating it to the support body 2, directly after the fixing of the latter on the first tooth D1, in a manner such to allow a wider maneuvering space and thus allow the orthodontist to have greater ease in the application.

[0068] In addition, it is advantageously possible to easily substitute the spacer bar 3 with another, even if different size, in case of need.

[0069] In operation, in order to install the device 1 in the mouth of a patient, the support body 2 is first temporarily glued on the first tooth D1, for example by means of a photopolymerization glue that initially is only applied without polymerization.

[0070] Subsequently, the spacer bar 3 with the hinging portion 31 is advantageously temporarily inserted in the housing seat 21, in a manner such to verify both the correct positioning of the support body 2, and the correct size of the spacer bar 2, which otherwise can be substituted.

[0071] In the event in which the support body 2 is correctly placed on the first tooth D1, the spacer bar 3 is removed and the support body 2 is fixed on the first tooth D1 by photopolymerizing the glue. Otherwise, the support body 2 can be moved in order to bring it into the suitable position, before definitively fixing it.

[0072] Subsequently, the spacer bar 3 is newly mounted on the support body 2 and its end portion 33 is fixed to the second tooth D2.

[0073] When both the support body 2 and the spacer bar 3 are fixed to the respective first tooth D1 and second tooth D2, the hinging portion 31 remains retained in the housing seat 21.

[0074] In accordance with a first embodiment variant, illustrated in FIGS. 2a, 3a, 4a and 5a, the hinging portion 31 has substantially cylindrical shape. In such case, the lateral surface 35 is preferably extended all around the hinging portion 31 and the central portion 33 of the spacer bar 3 is advantageously extended therefrom.

[0075] In accordance with a second embodiment variant, illustrated in FIGS. 2b, 3b, 4b, 5b, 7 and 9, the hinging portion 31 comprises a closure surface 36, which is connected with the lateral surface 35 by a peripheral edge 37. In such case, the hinging portion 31 advantageously has a cylindrical shape from which a portion parallel to the rotation axis R has been removed. In particular, the closure surface 36 is substantially flat and is extended to continue the lateral surface 35 into the removed cylindrical portion.

[0076] Advantageously, the central portion 33 of the spacer bar 3 is extended from the closure surface 36.

[0077] In accordance with the second embodiment variant, the hinging portion 31 is placed in the housing seat 21 in at least one operating position in which the peripheral edge 37 of the closure surface 36 is placed at the access mouth 22. In such situation, the entire closure surface 36 is advantageously coplanar with the peripheral edge 37.

[0078] Alternatively, in the operating position, the peripheral edge 37 of the closure surface 36, and preferably also the entire closure surface 36, is placed within the housing seat 21.

[0079] Advantageously, the second embodiment variant has the advantage that it allows the orthodontist to identify if the spacer bar 3 is placed in the correct operating position, i.e. in particular with its hinging portion 31 completely inserted in the housing seat 21.

[0080] In accordance with the preferred embodiment of the present invention, the end portion 33 of the spacer bar 3 comprises at least one hook 38 intended to be associated with an elastic tensioning element.

[0081] Advantageously, the end portion 33 of the spacer bar 3 comprises an end edge 39 opposite the hinging portion 31 and advantageously the hook 38 is extended along the extension direction D starting from the aforesaid end edge 39. Preferably, the hook 38 is extended in a direction opposite the hinging portion 31 of the spacer bar 3 and is advantageously substantially symmetric with respect to the extension direction D in order to ensure the possibility of installation in any dental arch. In particular, the hook 38 has spherical form, which has the further advantage of reducing the risk of irritating the oral mucous membranes of the patient in case of rubbing therewith.

[0082] Such configuration advantageously allows increasing the distance, in particular mesiodistal, between the second tooth D2 and a third tooth D3 to which the elastic tensioning element is connected. More in detail, the third tooth D3 is situated on the arch opposite that of the second tooth D2, and in particular it is a lower molar. Consequently, both the force F generated by the elastic tensioning element, and the application tilt with respect to a mesiodistal direction, are advantageously increased, as is illustrated for example in FIG. 11. Therefore, such configuration also allows increasing the ratio between the component of the force F along the extension direction D (mesiodistal) of the spacer bar 3 and the component of the force F along the rotation axis R (occlusogingival), with respect to a known configuration in which the hook is situated substantially at the center of the end portion 33.

[0083] In accordance with a further embodiment, illustrated in FIG. 10, the end portion 33 comprises two of the aforesaid hooks 38, advantageously shaped with curved form and in particular with facing concavities, i.e. defining a single concavity between them.

[0084] In such case, a first of the aforesaid hooks 38 is advantageously intended to be associated with a first elastic tensioning element connected to the third tooth D3, advantageously adapted to generate a first force F1. For example, the first elastic tensioning element can be associated with an attachment element to the third tooth D3 also provided with a respective attachment hook. Otherwise, a second of the aforesaid hooks 38 is advantageously intended to be associated with a second elastic tensioning element connected to the gums of the arch, on which the second tooth D2 is placed, and is advantageously adapted to generate a second force F2. For example, the second elastic tensioning element can be associated with a gum attachment element, i.e. an orthodontic implant of limited size, also provided with a respective attachment hook.

[0085] In this manner, it is possible to balance the occlusogingival components of the forces F1, F2 applied by using the first elastic tensioning element and the second elastic tensioning element, as illustrated for example in FIG. 12. The latter can be equivalent or even if different type, i.e. with different dimensions or elastic constant.

[0086] Of course, without departing from the protective scope of the present invention, it is possible to use the embodiment with two hooks 38 even only with one elastic tensioning element. In such case, the device 1 advantageously allows selecting such hook 38 is more suitable for use, based on the dental arch on which the device 1 itself is positioned.

[0087] In order to increase the ease of positioning of the support body 2, the latter comprises at least one marking line 25 parallel to one between the rotation axis R and the extension direction D. In particular, the marking line 25 is made in high-relief, for example during the forming of the same support body 2, and/or via incision, e.g. by means of laser incision.

[0088] Preferably, the support body 2 comprises an occlusogingival marking line 25 parallel to the rotation axis R, in particular placed on the support body 2 centrally along the extension direction D.

[0089] In addition, the support body 2 advantageously comprises a mesiodistal marking line 25 parallel to the extension direction D, in particular placed on the support body 2 centrally along the rotation axis R. In particular, the mesiodistal marking line 25 is placed at least along a section of the access mouth 22 of the housing seat 21.

[0090] Advantageously, the occlusogingival marking line 25 and the mesiodistal marking line 25 are perpendicular to each other and identify a central point of the support body.

[0091] Also forming the object of the present invention is an orthodontic device 1 having the characteristics previously described in the preferred embodiment, regardless of the specified form of the hinging portion 31 of the spacer bar 3 (which for example could even have spherical shape) and comprises at least one hook 38 extended starting from the end edge 39 of the end portion 33 along said extension direction D in a direction opposite the hinging portion 31.

[0092] In such case, therefore, the orthodontic device 1 according to the invention comprises a support body 2, which comprises an attachment base 20 intended to be fixed to a first tooth D1 and on which a housing seat 21 is made.

[0093] In addition, the device 1 comprises a spacer bar 3, intended to be placed to connect between the support body 2 and a second tooth D2, in which the spacer bar 3 itself comprises a hinging portion 31, a central portion 32 and an end portion 33.

[0094] In particular, the hinging portion 31 is rotatably connected to the support body 2 around a rotation axis R and is at least partially inserted within the housing seat 21 of the support body 2.

[0095] In addition, the central portion 32 is elongated and is mainly extended along an extension direction D starting from the hinging portion 31.

[0096] In addition, the end portion 33, is extended starting from the central portion 32 in opposite position with respect to the hinging portion 31 and is intended to be fixed to the second tooth D2. In particular, the end portion 33 comprises at least one hook 38 intended to be associated with an elastic tensioning element.

[0097] According to the invention, the end portion 33 comprises an end edge 39 opposite the hinging portion 31 and the hook 38 is extended along the extension direction D starting from the end edge 39. Preferably, the hook 38 is extended in opposite sense with respect to the hinging portion 31 and advantageously has spherical shape, in order to minimize the risk of irritating the oral mucous membranes of the patient in case of rubbing therewith.

[0098] Such configuration, as stated above, advantageously allows increasing the distance between the second tooth D2 and a third tooth D3 to which the elastic tensioning element is connected. More in detail, the third tooth D3 is situated on the arch opposite that of the second tooth D2, and in particular it is a lower molar. Consequently, both the force F generated by the elastic tensioning element, and the tilt of application with respect to a mesiodistal direction, advantageously increase. Therefore, such configuration also allows increasing the ratio between the component of the force F along the extension direction D (mesiodistal) of the spacer bar 3 and the component of the force F along the rotation axis R (occlusogingival), with respect to a known configuration in which the hook is situated substantially at the center of the end portion 33.

[0099] Since the orthodontic device 1 described now can be provided with any other characteristic of the preferred embodiment described above, it will not be further described hereinbelow.

[0100] Also forming the object of the present invention is an orthodontic device 1 having the characteristics previously described in the preferred embodiment, regardless of the specified form of the hinging portion 31 of the spacer bar 3 (which could for example also have spherical form) and has a spacer bar 3 with an end portion 33 comprising two hooks 38.

[0101] In such case, therefore, the orthodontic device 1 according to the invention comprises a support body 2, which comprises an attachment base 20 intended to be fixed to a first tooth D1 and on which a housing seat 21 is made.

[0102] In addition, the device 1 comprises a spacer bar 3, intended to be placed to connect between the support body 2 and a second tooth D2, in which the spacer bar 3 itself comprises a hinging portion 31, a central portion 32 and an end portion 33.

[0103] In particular, the hinging portion 31 is rotatably connected to the support body 2 around a rotation axis R and is at least partially inserted within the housing seat 21 of the support body 2.

[0104] In addition, the central portion 32 is lengthened and is mainly extended along an extension direction D starting from the hinging portion 31.

[0105] In addition, the end portion 33 is extended starting from the central portion 32 in opposite position with respect to the hinging portion 31 and is intended to be fixed to the second tooth D2. In particular, the end portion 33 comprises two hooks 38 each intended to be associated with an elastic tensioning element, which is advantageously intended to be connected to a third tooth D3. More in detail, the hooks 38 are shaped with curved form and in particular with facing concavities, i.e. defining a single concavity between them.

[0106] In such case, a first of the aforesaid hooks 38 is advantageously intended to be associated with a first elastic tensioning element connected to the third tooth D3, advantageously adapted to generate a first force F1. For example, the first elastic tensioning element can be associated with an element of attachment to the third tooth D3 also provided with a respective attachment hook. Otherwise, a second of the aforesaid hooks 38 is advantageously intended to be associated with a second elastic tensioning element connected to the gums of the arch on which the second tooth D2 is placed, and is advantageously adapted to generate a second force F2. For example, the second elastic tensioning element can be associated with a gum attachment element also provided with a respective attachment hook.

[0107] In this manner, it is possible to balance and preferably cancel the occlusogingival components of the applied forces F1, F2 by using the first elastic tensioning element and the second elastic tensioning element. The latter can be equivalent or even of different type, i.e. with different size or elastic constant.

[0108] Of course, without departing from the protective scope of the present invention, it is possible to use the embodiment with two hooks 38 even only with one elastic tensioning element. In such case, the device 1 advantageously allows selecting such hook 38 is more suitable for use, based on the dental arch on which the device 1 itself is positioned.

[0109] Since the orthodontic device 1 described now can be provided with any other characteristic of the preferred embodiment described above, it will not be further described hereinbelow.

[0110] Also forming the object of the present invention is an orthodontic kit for treating malocclusions which advantageously comprises an orthodontic device 1, or part thereof, of any type described above.

[0111] According to the invention, the orthodontic kit comprises at least one support body 2 and a plurality of spacer bars 3 of the orthodontic device 1 of any one of the above-described embodiments. Preferably, the support body 2 and the spacer bars 3 of the kit are disassembled from each other, such to allow the orthodontist to select the suitable the spacer bar 3.

[0112] Advantageously, each of the spacer bars 3 is provided with an elongated central portion 32 with length different from that of the other said spacer bars 3.

[0113] In this manner, the orthodontic kit advantageously allows not only the interchangeability of the spacer bars 3, but also the possibility to select the spacer bar 3 with the length most suitable for the patient without having to purchase new devices in case of error.

[0114] The invention thus conceived therefore attains the pre-established objects.

[0115] The contents of the Italian patent application number 102023000002970, from which this application claims priority, are incorporated herein by reference.