Maxillary molar displacement device

Abstract

1. A device for the displacement of a maxillary molar (M) with a mesial palatal cusp, comprising: a support (12) intended to be fixed to a molar (M); a rod (14) with a first end (14.1), the first end being fixed to the palate bone or to at least one tooth adjacent to the molar (M) such that the rod has a given position relative to the molar (M) when the device is in place; a rotation hinge (A1) between a support (12) and a rod (14), the rotation hinge (A1) being fixed relative to said rod (14) and having an axis of rotation (X1) perpendicular to the occlusal plane, the axis of rotation (X1) being located near the mesial palatal cusp of the molar (M); a spring for applying a force to rotate the molar (M) around a rotation axis (X1) to the palatal surface of the molar (M) so that the molar (M) has a distal rotation; An apparatus comprising:

Description

[Technical field]

[0001] The present invention relates to a displacement device in the field of orthodontics, and more particularly to a maxillary molar displacement device.

[0002] The object of the present invention is to solve the occlusion problems of the maxillary permanent molars and the teeth in front of them in the sagittal direction. [Background technology]

[0003] The maxillary molars, due to their anatomical structure, present the potential for rotation. In fact: -Contains three roots, namely two vestibular roots and a long palatal root that forms the axis of pivot for the maxillary molars. -Furthermore, the maxillary molar contains four cusps, the three most important of which form a triangle, the apex of which is the mesial palatal cusp, which is located just above the palatal root. -Furthermore, in normal occlusion, the mesial palatal cusp rests in the central fossa of the opposing mandibular molar. -The three roots of the maxillary molars lie within the alveolar bone, sandwiched between two dense walls of bone known as cortical bone, which further facilitates their rotation. -Finally, the small dimensions of the maxillary mesial premolars in the palatal-vestibular direction tend to convert mesial translational movements of the maxillary molars into mesial rotational movements. -The maxillary molars are trapezoidal in shape.

[0004] The upper molars tend to exhibit a mesial rotation, i.e. anterior rotation, when subjected to the stress of masticatory forces. This rotation plays a role of natural compensation in adapting to occlusal problems. The inventors of the present invention have discovered that this mesial rotation is an indirect cause of the occurrence of crowding of the mandibular incisors. In fact, the fact that the vestibular cusps are too far forward in the dental arch is the cause of occlusal disorders that prevent proper occlusion and generate force vectors on the mandibular teeth, ultimately leading to crowding of the lower incisors. The inventors of the present invention have explained this phenomenon in De Baets, J. and Chiarini, M.: The Pseudo-Class I, a newly defined type of malocclusion, J. Clin. Orthod 29:73-88, 1995, and De Baets, J.: The role of the upper first molar in lower incisor crowding, J. Clin. Orthod. 29:146 157, 1995.

[0005] To create space for the canines and maxillary incisors, appliances are usually used that tend to move the maxillary molars in translation to move them posteriorly. However, this translation has not proven effective in the long term. In fact, when the maxillary molars are translated, the mesial palatal cusps move out of the fossa of the opposing mandibular molar.

[0006] Over time, this cusp seeks a position in the central fossa and therefore tends to move forward, thus indirectly contributing to the incisor crowding mentioned above. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] De Baets, J. and Chiarini, M.: The Pseudo-Class I, a newly defined type of malocclusion, J. Clin. Orthod 29:73-88, 1995, and De Baets, J.: The role of the upper first molar in lower incisor crowding, J. Clin. Orthod. 29:146 157, 1995 Summary of the Invention

[0008] Therefore, one of the objects of the present application is to provide a displacement device that allows for efficient and sustained movement of maxillary molars.

[0009] The above mentioned object is achieved by a displacement device intended to be applied to one of the maxillary molars, configured to apply at least one torque to said maxillary molar so as to tend to have a distal rotational movement about its palatal root, the axis of rotation of the tooth being fixed by the device. The invention applies mainly to the maxillary first molar, but is also applicable to the maxillary second molar.

[0010] Indeed, in particular by applying a distal rotation to the maxillary first molar while keeping the axis of rotation fixed, the trapezoidal shape of the maxillary first molar when viewed from above frees up the space between the molar and the premolar and allows the canines and incisors to be repositioned.

[0011] The inventors of the present invention have discovered that if the mesial palatal cusp is correctly positioned in its fossa, it will be maintained in the fossa during rotational displacement, and therefore will no longer have a tendency to advance and re-establish crowding of the mandibular incisors after treatment is completed.

[0012] If the mesio-palatal cusp is not correctly positioned in the opposing fossa, the appliance provides simultaneous rotational and translational displacement to reposition the mesio-palatal cusp in the opposing fossa, so that after treatment is completed, the mesio-palatal cusp no longer has a tendency to move and re-establish crowding of the mandibular incisors.

[0013] An orthodontic appliance is an apparatus that applies rotation to one of the maxillary molars about a fixed axis of rotation that is parallel to and close to the natural axis of rotation of that maxillary molar passing through its palatal root and its mesial palatal cusp located in the opposing fossa.

[0014] The device is intended to be fixed to the maxillary molars near their natural axis of rotation and comprises a fixed axis of rotation and means for exerting a force on said maxillary molars so as to exert a rotational torque on said maxillary molars about the fixed axis of rotation. This force may be exerted on the palatal or vestibular side. This force may be exerted, for example, by tension, compression or torsion springs or repelling magnets.

[0015] In one embodiment, the device is intended to be fixed palatally, either to the palatal bone or to one or more teeth in the vicinity of the maxillary molars, such as premolars and / or primary molars.

[0016] In another embodiment, the device comprises an interdental bone anchor or is intended to be fixed to the cheekbone. In one variation, the device comprises an extraoral portion that is attached to the skull or nape of the neck.

[0017] In one embodiment, the appliance comprises a ring that surrounds the molar and secures the maxillary first molar to the appliance, hi another embodiment, the appliance comprises a bracket that is bonded to the molar.

[0018] In other words, the device according to the invention has a fixed centre of rotation close to the axis of rotation of the molars and makes it possible to hold the mesial palatal cusps in the opposing fossae. The force causing the rotation can be applied on the vestibular or palatal side.

[0019] The axis of rotation may simultaneously undergo distal rotation and distal or mesial translation, making it possible to reposition the mesial palatal cusp in the fossa.

[0020] Some embodiments offer the advantage of not requiring patient cooperation.

[0021] Thus, one of the subjects of the present application is a device for the displacement of maxillary molars with mesial palatal cusps, comprising: a support intended to be attached to the maxillary molars; a rod with a first end, the first end intended to be fixed to the palatine bone or to at least one tooth adjacent to the maxillary molars, such that the rod has a given position relative to the maxillary molars when the device is in place; a rotation hinge between a support and a rod, the rotation hinge having an axis of rotation fixed relative to the rod and intended to be perpendicular to the occlusal plane, the axis of rotation intended to be located near the mesial palatal cusps of the maxillary molars; means configured to apply a force to either the palatal surface of the molar or the vestibular surface of the molar capable of rotating the maxillary molar about an axis of rotation such that the maxillary molar rotates in a distal direction; The device comprises:

[0022] In one exemplary embodiment, the rod is provided with a pin intended to form an axis of rotation and the support is provided with a housing for said pin, or alternatively, the support is provided with a pin intended to form an axis of rotation and the rod carries a housing for said pin, the assembly of the pin and the housing forming a rotation hinge.

[0023] In one embodiment, the means configured to apply a force to the palatal surface of the maxillary molar capable of applying a rotation to the maxillary molar comprises at least one torsion spring comprising a coil and two radially extending strands, the coil being attached to a pin, one strand being fixed to a support and the other strand being fixed to a rod, the attachment of the other strand to the rod resulting in loading of the spring.

[0024] The housing may have a lateral opening over its entire height to allow the coil to be positioned by lateral displacement of the spring, said housing having a lateral slot for passing a strand fixed to the support.

[0025] In another embodiment, the means configured to apply a force to the palatal surface of the molar capable of applying a rotation to said maxillary molar comprises a tension spring intended to be fixed by a first end intended for the palatal bone or one or more adjacent teeth, and fixed to the support at a position different from the pivot hinge.

[0026] In another embodiment, the means configured to apply a force capable of applying rotation to the palatal surface of the maxillary molar comprises a tension spring mounted around the rod and secured by a first end to the rod toward the first end of the rod, the device further comprising a bar having one end that slides along the rod and one end that is secured to the support at a location different from the pivot hinge, the second end of the spring being secured to the end of the bar that slides on the rod.

[0027] In another embodiment, the means configured to apply a force to the vestibular surface of the molar capable of applying a rotation to said maxillary molar comprises a part rotatably articulated on a support, said part being located on the vestibular surface of the molar, and elastic means or repelling magnets exert a force on said articulated part. The means configured to apply a force to the vestibular surface of the molar may be configured to be fixed between two teeth or to the cheekbone, or may be extra-oral and fixed to the patient's skull or neck.

[0028] The displacement device may further comprise means configured to apply a force capable of moving said maxillary molar in translation.

[0029] The means configured to apply a force capable of moving the maxillary molars in translation may comprise compression springs, or magnets oriented relative to each other so as to repel each other.

[0030] For example, a rod may have a first portion and a second portion configured to slide relative to one another, a compression spring may be mounted on the rod with repulsion between the first and second portions, or a magnet may be mounted on the first and second portions.

[0031] Very conveniently, the first and second parts have a cross-section such as to prevent relative rotation about their axis.

[0032] The support is a ring intended to be attached around the maxillary first molar and / or the displacement device comprises a bracket fixed to one or more teeth adjacent to the maxillary first molar, with a first end of the rod fixed to the bracket. [Brief description of the drawings]

[0033] The following description will be better understood with the aid of the accompanying drawings.

[0034] [Figure 1] FIG. 2 is a schematic diagram of a portion of the maxillary dentition. [Diagram 2] FIG. 2 shows a view from below of an example of a palatal displacement device according to a first embodiment, with the spring in an activated state. [Diagram 3] FIG. 3 is a detailed view of FIG. 2. [Figure 4] FIG. 1 shows a schematic diagram of a torsion spring for use in the present invention. [Diagram 5] FIG. 3 is a view of the displacement device of FIG. 2 with the spring in an unactuated state. [Figure 6]FIG. 2 is a perspective view of another example of a palatal displacement device according to the first embodiment (spring not shown). [Figure 7] FIG. 2 is a plan view of another example of a palatal displacement device according to the first embodiment. [Figure 8A] FIG. 2 is a perspective view of another example of a palatal displacement device according to the first embodiment. [Figure 8B] FIG. 8B is a close-up view of a housing implemented by the device of FIG. 8A. [Figure 9] FIG. 2 is a perspective view of another example of a palatal displacement device according to the first embodiment. [Figure 10] FIG. 13 is a perspective view of an example of a palatal displacement device according to a second embodiment. [Figure 11A] FIG. 13 is a perspective view of an example of a palatal displacement device according to a third embodiment. [Figure 11B] FIG. 11B is a schematic diagram of a cross section of the rod and sleeve of the device of FIG. [Figure 12] FIG. 13 is a perspective view of another example of a palatal displacement device according to the third embodiment. [Figure 13] FIG. 13 is a plan view of another example of a palatal displacement device according to the third embodiment. [Figure 14A] FIG. 13 is a plan view of another example of a palatal displacement device according to the third embodiment. [Figure 14B] FIG. 14B is a plan view of one variation of the device of FIG. 14A. [Figure 15] FIG. 13 is a plan view of another example of a palatal displacement device according to the third embodiment. [Figure 16A] 13A-13C are schematic diagrams of another example of a palatal displacement device according to a second embodiment before and after centrifugal rotation. [Figure 16B] FIG. 16B is a schematic diagram of the palatal displacement device of FIG. 16A after centrifugal rotation. [Figure 17] FIG. 13 is a top view of another example of a torsion spring configured for application to a palatal displacement device. [Figure 18] FIG. 1 is a schematic diagram of an example of a vestibular displacement device. [Figure 19] FIG. 13 is a schematic diagram of an example of a portion of a means for enabling the application of a rotational force adapted to a vestibular displacement device. [Figure 20A] FIG. 13 is a schematic diagram of an example of another portion of a means for enabling the application of a rotational force adapted to a vestibular displacement device. [Figure 20B] FIG. 13 is a schematic diagram of one variation of a means enabling the application of a rotational force adapted to the vestibular displacement device. [Figure 20C] FIG. 13 is a schematic diagram of another variant of the means enabling the application of a rotational force adapted to the vestibular displacement device. [Figure 21] FIG. 13 is a schematic diagram of another example of a vestibular displacement device. [Figure 22] FIG. 1 is a schematic diagram of an example of a vestibular displacement device. [Figure 23A] FIG. 1 is a schematic diagram of an example of a vestibular displacement device. [Figure 23B] FIG. 23B is a schematic diagram of one variation of the device shown in FIG. 23A. [Figure 24A] FIG. 13 is a perspective view of another example of a displacement device according to the third embodiment; [Figure 24B] FIG. 24B is a cross-sectional view of one variation of the device of FIG. 24A. [Figure 25A] FIG. 13 is a perspective view of another example of a displacement device according to the third embodiment, shown in perspective; [Figure 25B] FIG. 25B is a diagram of the device of FIG. 25A in a disassembled state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In FIG. 1 one can see a schematic diagram representing a portion of the maxillary dentition seen from below, which allows the definition of the various terms used in the description.

[0036] The present invention is intended to apply at least one rotational force to one of the maxillary molars, and is particularly suited to applying a rotational force to the first molar. The following description is directed to application of the device to the maxillary first molar, conveniently referred to as the "maxillary molar" or "molar." However, the present invention is applicable to both the maxillary first molar and the maxillary second molar.

[0037] The present invention relates to a displacement device configured to apply a force to the palatal side of a molar, referred to as a "palatal displacement device," and to a displacement device configured to apply a force to the vestibular side of a molar, referred to as a "vestibular displacement device."

[0038] Reference M denotes the maxillary first molar, M' denotes the maxillary second molar, PM1 and PM2 denote premolars, PM2 being the mesial premolar.

[0039] Reference number 2 indicates the mesial vestibular cusp, reference number 4 indicates the distal vestibular cusp and reference number 6 indicates the mesial palatal cusp.

[0040] Reference number 8 refers to the mesial (anterior) portion of the molar M and reference number 10 refers to the distal (posterior) portion of the molar. The vestibular surface of the molar is the outer surface and the palatal surface is the inner surface.

[0041] The terms "anterior" and "posterior" are considered relative to the incisors, with anterior pointing towards the incisors and posterior pointing away from the incisors.

[0042] In the reference position, Class I occlusion, the mesial palatal cusp of the maxillary first molar rests in the central fossa of the opposing molar.

[0043] In FIG. 2 an example of a palatal displacement device D1 according to the first embodiment can be seen from below.

[0044] The device D1 comprises a ring 12 configured to be placed around a molar tooth M to form a hoop. The ring 12 is, for example, bonded to the molar tooth M such that the molar tooth M and the ring 12 are fixed to one another in movement. A tubular housing 13 having an axis perpendicular to the occlusal plane is fixed to the medial or palatal surface of the ring 12. The tubular housing 13 is positioned on the ring 12 such that it is located near the mesial palatal cusp when in position on the molar tooth.

[0045] Furthermore, the device comprises an element 14 intended to be fixed in the patient's mouth, i.e. a bone anchor, called "fixation element 14", formed by a rod, the first end 14.1 of which is intended to be fixed to the palate bone. For this purpose, the first end 14.1 comprises a loop for receiving a screw 16 which is screwed into the palate. The second end 14.2 of the rod 14 forms a pin 15 adapted to remain in the tubular housing 13. The rod 14 is intended to be immobile relative to the palate.

[0046] The pin 15 and the tubular housing 13 form a pivot hinge A1 with a fixed axis of rotation X1, which is substantially parallel to the natural axis of rotation of the molar tooth passing through the palatal root and the mesial palatal cusp lodged in the opposing fossa. The axis X1 of the hinge A1 is located as close as possible to the natural axis of rotation of this molar tooth. In FIG. 3 an enlarged view of the pivot hinge A1 can be seen.

[0047] Furthermore, the device D1 comprises a means 18 configured to apply a force to the molar teeth so as to have a distal rotational movement.

[0048] By "distal rotational movement" is meant the rotational movement of the vestibular surface of the molar about the axis of rotation of the molar toward the rear of the jaw, as indicated by arrow F.

[0049] The means 18 comprises a torsion spring 19 .

[0050] In Fig. 4 one can see a spring 19G intended to act on the left molar and a spring 19D intended to act on the right molar. The torsion spring comprises a coil 20 and two radially extending strands 22.1, 22.2. The coil 20 has a tendency to return the strands 22.1, 22.2 to their rest position. Preferably, the torsion spring is attached to the ring 12, the coil 20 is fastened to the tubular housing 13 and the free end of the strand 22.2 is received in a sleeve 17 attached to the inner side of the ring 12. In the example shown, the strand 22.2 is straight.

[0051] As can be seen from figure 2, the inner diameter of the coil is sufficient for fitting around a tubular housing, into which the pin is inserted. The device comprises means for loading the spring. In this example, this means is formed by a hook 24 provided at the free end of the strand 22.1, directed towards the bone anchor and intended to be attached to the rod 14.

[0052] When the device D1 is placed on a molar, the strand 22.1 pivots and the hook 24 attaches to the rod 14 (FIG. 2). In FIG. 5, the strand 22.1 is not hooked onto the rod 14, so the spring is not activated.

[0053] Next, the operation of the device D1 will be described.

[0054] In FIG. 5 a schematic diagram of the action of the device D1 on a molar tooth M can be seen.

[0055] In FIG. 5, the torsion spring 19 exerts a force on the ring 12 in a counterclockwise direction and is itself guided for rotation about the axis X1 of the fixed pivot hinge A1.

[0056] The ring 12 is rotationally fixed to the molar M, which is driven to rotate in a distal direction, which in this case corresponds to a counterclockwise rotation. Because the axis of rotation X1 is fixed, the mesial palatal cusp is held in place in the fossa.

[0057] The molars have a trapezoidal shape and this distal rotational movement frees up the space between the molars and the premolars, which then makes it possible to act on the canines and incisors by repositioning them to the desired position.

[0058] In figure 6 one can see a variant of the palatal displacement device D2, in which a tubular housing 113 is fixed to the second end 14.2 of the rod 14 and a pin 15 is fixed to the inner side of the ring 112. In this variant, the housing 113 is received in the coils of a torsion spring (not shown).

[0059] According to another exemplary embodiment of the palatal displacement device shown in Fig. 7, the device D3 is fixed not to the palatal bone but to adjacent teeth, such as the first and second premolars PM1 and PM2 or primary molars. In this example, the device comprises a bracket 26 shaped to be fixed to the palatal surfaces of the premolars PM1 and PM2. The rod 14 is fixed to the bracket 26 by a first end 14.1. The remainder of the device is similar to device D1.

[0060] In figures 8A and 8B one can see a palatal displacement device D4 according to another variant embodiment, in which the housing 213 is vertically open to allow the insertion of a coil of a torsion spring (not shown), the housing 213 forming a kind of cradle for the pin 15 and the coil. Furthermore, the wall of the housing is provided with a lateral slot 30 for the passage of the strand 22.2 of the torsion spring. This variant embodiment allows for an easier installation of the pin and the spring.

[0061] The ring 212 with the open housing 213 can be conveniently manufactured by additive manufacturing, also known as "3D printing."

[0062] In Fig. 9 one can see a palatal displacement device D5 according to a first embodiment, where the axis of rotation X1 of the rotation hinge is offset, rather than directly on the inner surface of the ring 412. In this example, the housing 413 is rigidly connected to the fixing element 14. Nevertheless, the axis of rotation X1 remains close to the side of the ring and the mesial palatal cusp, and thus close to the natural axis of rotation of the molar. The coils of the spring 19 are attached around the housing 413. This embodiment offers the advantage of giving the mesial palatal cusp more freedom when subjected to chewing forces.

[0063] In FIG. 10 an example of a palatal displacement device D6 according to the second embodiment can be seen, in which the means for exerting a rotational force on the molar comprises a tension spring 27 fixed by a first end 27.1 to the rod 14 on the side of the first end 14.1 and by a second end 27.2 to a curved bar 28 fixed to the inner side of the ring 12 in a retracted position relative to the housing 13.

[0064] The tension spring 27 comprises, for example, a projection of the rod 14 and a loop at each end attached to a bar 28 .

[0065] The spring 27 exerts a tension force on the curved bar 28, which causes the ring 12 to move in a clockwise direction (symbolized by the arrow) shown in FIG. 10, which is guided to rotate about the axis X1 of the fixed pivot hinge A1.

[0066] In certain circumstances, it may be desirable to apply a force to the molar simultaneously with the application of the rotational force to apply a force that translates the molar back to the mesial palatal cusp into the opposing fossa. In the example of the third embodiment described below, the orthodontic appliance allows for both distal rotation of the molar and translational displacement of the molar, which may be posterior (distal translation or distal movement) or anterior (mesial translation or mesial movement).

[0067] In FIG. 11A one can see an example of a palatal displacement device D7 according to a third embodiment, which is capable of applying both rotational and translational forces to the molar teeth.

[0068] Device D7 is similar to device D1 with respect to the means for rotating the molars.

[0069] In this example, the device D7 comprises a fixing element 414 comprising a rod 414a fixed by one end to the palate and a sleeve 414.b slidably mounted on the rod 414.a. The sleeve 414.b carries a pin 15 housed in a housing 413 attached to the ring. The translation is driven by a tension or compression spring (not shown) mounted on the rod 414.a acting on the sleeve 414.b. Means are provided to stop the translational movement, for example a screw 16 passing through the sleeve 414.b. The length of the rod 414.a can be changed during the treatment or can be permanently fixed during the treatment.

[0070] As shown diagrammatically in Fig. 11B, it is highly advantageous for the sleeve 414.b and the rod 414.a to have a cross section which prevents relative displacement in rotation about their axis, thereby making it possible to hold the pin 15 perpendicular to the occlusal plane. For example, the sleeve 414.b and the first part 414.a have a rectangular cross section. A screw 416 fixes the two parts in translation.

[0071] In this example, the torsion spring is not shown.

[0072] It will be appreciated that other shapes for the various parts are contemplated. Additionally, the housing may be carried by the second part and the pin carried by the ring.

[0073] In FIG. 12 another example of a palatal displacement device D8 according to the third embodiment can be seen.

[0074] In this example, device D8 comprises a ring 512 with a sleeve 17 located on the outer surface of ring 512 oriented perpendicular to the axis of the ring and parallel to the occlusal plane, and receiving a strand of a torsion spring.

[0075] Device D8 comprises a torsion spring 518, the coil of which is fitted around pin 15, one strand 522.2 being slipped into sleeve 17 of ring 512, and the other strand 522.1, which serves to activate the spring, is provided with a hook which hooks onto fixing element 514 to load the spring. The coil of spring 518 is fitted around pin 15 which is part of rod 514.

[0076] The fixing element 514 comprises a first part 514.a which is a sleeve intended to be fixed to the palate bone, and a second part 514.b formed by a rod carrying a pin 15 and sliding in the first part 514.b. A screw 35 makes it possible to fix the rod 514.b in the sleeve 514.a.

[0077] A translational spring 33 is attached between the first part 514.a and the second part 514.b and can exert either a compressive or tensile force. The spring is intended to exert a compressive or tensile force to move the teeth in distal or mesial translation, respectively.

[0078] In the remainder of this specification, springs intended to move teeth in translation will be referred to as "translation springs", whether they act in compression or tension.

[0079] Furthermore, the device D8 comprises means for actuating the spring 33 in compression or tension and setting its load. In this example, these means comprise a slide 37 slidably mounted on the rod 514.b between the molar M and the fixed sleeve 514.a. The translational spring 33 presses on the slide 37 fixed on the rod 514.b, causing the rod 514.b to slide and resulting in a centrifugal movement in translation of the pin 15.

[0080] The slide 37 is provided with a screw 39 which axially secures the slide 37 to the second part 514.b and determines the load level of the spring 33.

[0081] Preferably, similar to device D7, the first part 514.a and the second part 514.b have, for example, a square or rectangular cross section and are rotationally fixed relative to each other.

[0082] In FIG. 24A a further example of a palatal displacement device D14 according to the third embodiment can be seen.

[0083] On the one hand, in this example, the tubular housing 1513 is slidably mounted on a rod 1514a (shown in dotted lines) fixed to the palate and fixed to the second end 1514.1 of a sleeve 1514b, and the pin 1515 is fixed to the inner side of the ring 1512 (also shown in dotted lines). The housing 1513 is connected to the sleeve 1514b by a base 1517 having a hole 1517a intended to receive a strand 1518.1 of a torsion spring 1518. The coils of the torsion spring are mounted around the tubular housing 1513. The other strand 1518.2 is intended to cooperate with the crown to activate the spring.

[0084] As a variant, as in device D5, the pivot hinge is not located directly on the inner surface of the ring 1512, but is offset. In this example, the pin forming the axis of rotation is fixed to the end of the fixing element 14. The axis of rotation X1 is just in front of the sleeve that receives one end of the torsion spring, still close to the natural axis of rotation of the side of the ring and the mesial palatal cusp, and thus of the molar. The coils of the spring 19 are attached around the pin, and the device acts on the molar via the end of the spring received in the sleeve. This embodiment offers the advantage of leaving more freedom for the mesial palatal cusp when subjected to chewing forces.

[0085] Advantageously, sleeve 1514b has a polygonal inner cross-section and rod 1514a has a polygonal cross-section to prevent rotation of the tube around rod 1514a.

[0086] On the other hand, like device D8, device D14 comprises a translation spring (not shown) and a means (not shown) for loading the translation spring, for example a rubber band stretched between the pin and the tooth and exerting a mesial force.

[0087] The device D14 offers the advantage of being simple in construction.

[0088] As a variant, the sleeve 1514b' is not completely closed on itself, as shown in FIG. 24B, and its shape is such as to ensure translational guidance along the rod.

[0089] In one example, the housing 1513 and the sleeve 1514b are 3D printed.

[0090] Device D14 may not include a translational spring for applying compression or tension, and may only be intended to apply centrifugal rotation in a manner similar to device D5.

[0091] In another example, the housing 1513 is fabricated by 3D printing or machining, and the sleeve is fabricated by machining or bending and welded to the housing.

[0092] In FIG. 25A we can see another exemplary embodiment of device D15 according to a third highly advantageous embodiment, since it can be used to apply both distal rotation and distal movement, or both mesial rotation and mesial movement.

[0093] In FIG. 25B a view of the device in an exploded state can be seen.

[0094] Additionally, device D15 offers the advantage of providing a shroud to protect the translating spring which makes the device extremely easy to install and maintain.

[0095] The device D15 comprises a sleeve 1614b of similar shape to the sleeve of the device D14, and a pin 1615 fixed to the end of the sleeve 1614b and forming an axis of rotation. A torsion spring 1618 is mounted around the pin 1615. The device D15 acts on the molar by means of a strand 1618.1 of the torsion spring 1618 received in a sleeve fixed on the outer surface of a ring attached to the molar.

[0096] Alternatively, the pin 1615 is hollow and forms a housing for the pin secured with a ring in a manner similar to device D14.

[0097] In this example, the sleeve 1614b as well as the rod 1614a are square in cross section, although alternatively any other polygonal shape can be used.

[0098] Device D15 comprises a translating spring 1633 and a shroud C that covers the translating spring and a portion of the sleeve 1614b. In this example, shroud C consists of two parts including a sleeve C1 and a plug B1 that are fixed together, for example by welding.

[0099] The translation spring is fixed by a first end to the sleeve 1614b and by a second end to the rod 1614a. In the example shown, the spring 1614b comprises at its first end a curved strand 1614b.1 housed in a hole 1614c formed in a cutout of the sleeve 1614b and at its second end a curved strand 1614b.2 received in a hole formed in the shroud, more specifically in the plug B1. The shroud is fixed to the rod by a screw (not shown). In the example shown in Figures 25A and 25B, the plug B1 comprises a hole P1 for receiving a screw (not shown) intended to fix the shroud to the rod.

[0100] Adjustment of the translation spring load and its action in translation or tension is simply accomplished by sliding the shroud over rod 1614a and securing it with a screw.

[0101] Next, placement of device D15 in the patient's mouth will be described.

[0102] The rod 1614a is first fixed to the palate. The pre-assembled device D15 is fitted around the rod 1614a, which enters the translation spring 1633 and the sleeve 1614b, and the crowned pin 1615 is inserted into the housing 1613.

[0103] The free strand of torsion spring 1615 is slipped into a sleeve provided on the crown similar to the sleeve seen in FIG.

[0104] A screw is then inserted into the hole P1 of the plug B1 in order to set the action of the translational spring in tension or compression and to adjust its load. In fact, when the shroud is moved closer to the sleeve, the spring is compressed, and when the shroud is moved away from the sleeve, stretching the translational spring fixed to the sleeve and to the shroud, the spring is tensioned.

[0105] Installation and adjustment of the device is therefore greatly simplified.

[0106] The device is easy to handle and maintain since the translation spring 1633 is completely covered. Additionally, the device presents an improved visual appearance.

[0107] In FIG. 13 an example of a palatal displacement device D9 according to a third embodiment can be seen, the device comprising a first part extending according to a first axis Y1 and a second part extending according to a second axis Y2 perpendicular to the axis Y1.

[0108] In this example, the housing 613 is carried by a ring and the pin 15 is carried by a fixing element 614. The fixing element 614 is telescopic.

[0109] In this example, the rod 614 comprises a first part 614.a fixed to the palate, a second part 614.b carrying a pin and a third part 614.c formed by a threaded rod onto which the first and second parts are screwed. A knurled wheel 41 is fixed for rotation with the threaded rod 614.c and is arranged between the first and second parts. By rotating the knurled wheel, the threaded rod 614.c rotates, causing the first and second parts fixed in rotation to move away from each other or towards each other. Furthermore, the device comprises means (not shown) for preventing relative rotation between the parts 614.a and 614.b. These means comprise, for example, two bars parallel to the axis Y1 and arranged on either side of the rod 614. The bars are fixed by one end to the first part 614.a and by the other end to the second part 614.b. Two bars fixed to the portions 614.a and 614.b fix the portions 614.a and 614.b in rotation relative to each other.

[0110] The adjustment system can be replaced by any other device known to those skilled in the art, such as the device sold under the trademark Variety SP Maxi by the company Dentaurum. Other adjustment devices are also manufactured by Leone and Rocky Mountain. These devices use a key to change the settings.

[0111] In Fig. 14A one can see another example of a palatal displacement device D10 according to the third embodiment, with a telescopic fixation element 714 including a first part 714.a formed by a rod intended to be fixed to the palatal bone and a second part 714.b formed by a sleeve rigidly carrying a hinge pin. In this example, the pin is not aligned with the axis of the rod, but a bar 43 is fixed laterally to the sleeve 714.b, the free end of which carries the pin 15. In this example, the bar 43 is fixed to the rod by a screw 45, which allows the adjustment of the bar 43 relative to the housing receiving the pin and also serves to hook the strand 722.1 of the torsion spring 719 and ensure its activation.

[0112] The first part 714.a comprises a first part slidably mounted within the sleeve 714.b. Preferably, the first part 714.a and the sleeve 714.b have a rectangular or square cross section, more generally a cross section which prevents their relative rotation about their axis. A screw 47 passing through the sleeve 714.b clamps the first parts and ensures their relative fixation.

[0113] The portion of the first part that does not slide into the second part is circular in cross section, threaded and is fitted with a knurled wheel 49. A compression spring is fitted around the threaded portion between the knurled wheel 49 and the second part. Displacement of the wheel makes it possible to vary the action and load of the translational spring.

[0114] In FIG. 14B it can be seen an alternative embodiment of the device D10 in which the compression spring is replaced by two magnets MG oriented relative to each other so as to repel each other.

[0115] It should be noted that in device D8 of FIG. 12, spring 33 can be replaced by two magnets oriented relative to each other so as to repel or attract each other depending on the desired operation, e.g. one magnet can be carried by first portion 514a and the other by slide 37.

[0116] In FIG. 15 another example of a palatal displacement device D11 according to the third embodiment can be seen, where the device is fixed to adjacent teeth.

[0117] In this example, a bracket 826 fixed to an adjacent tooth fixes the orientation of the rod 814 and has two fixed collar-shaped supports 36 aligned to allow the rod 814 to slide. The rod 814 carries a pin 15.

[0118] Means are provided to ensure axial fixation of the rod 814, such as, for example, a screw 16 passing through one or both collars.

[0119] The device comprises a translational spring 33 attached to a rod 814 .

[0120] Furthermore, the device D11 comprises means for loading a translation spring 33. In this example, the rod 814 comprises a slide 37 slidably mounted between two collars. The translation spring 33 presses against the slide 37 fixed to the rod 814, causing the rod 814 to slide and thus resulting in a distal or mesial translational movement of the pin 15 housed in the support.

[0121] In Fig. 15 the torsion spring 819 is not activated. Also in this example the torsion spring 819 comprises a loop 819.1 on one of its strands. The implementation of such a spring in an orthodontic device according to the invention further improves the effectiveness of the device, i.e. reduces parasitic effects on the adjacent teeth. This spring can be implemented in any device that comprises a torsion spring.

[0122] Preferably, at least one of the two parts has a rectangular or square cross-section to prevent relative rotation of the two parts about their axis.

[0123] In Fig. 16A and Fig. 16B it is possible to see a palatal displacement device D12 according to a second embodiment in which a rotational force is obtained by a translational movement.

[0124] In this example, the ring 912 comprises a housing 913 which receives a pin 15 which fixes the axis of rotation. Furthermore, it comprises an element 38 for fixing a rod 40 intended to apply a tension force.

[0125] The device comprises a fixing element 914 intended to be fixed to the palate by a first end 914.1 and formed by a rod carrying a pin 15 at a second end 914.2.

[0126] The device further comprises a rod 40 comprising a first end 40.1 slidably attached to the fixed rod and a second end 40.2 articulated to the element 38. For example, the first end 40.1 of the rod 40 comprises a slide which slides around the rod 914. The device further comprises a tension spring 927 attached to the fixed rod 914 and fixed to the slide of the articulated rod 40 and exerting a tension force on the first end 40.1 of the articulated rod 40.

[0127] 16A and 16B show the action of the device on a molar: the articulated rod 40 exerts a traction force on the molar at the element 38, causing the element 38 to pivot distally about a fixed axis of rotation X1.

[0128] In Fig. 17 another example of a torsion spring 1019 can be seen, which is combined with a cap 42 that covers the strands of the spring on one side. The other side of the spring is left free to allow a pin to be inserted into the coil and the strands of the spring to be hooked onto a ring and rod. Preferably the spring is provided with a cap and attached to the device.

[0129] Next, the vestibular displacement device will be described.

[0130] The vestibular displacement device is configured to apply a distal force to the molars on the vestibular side, causing a distal rotation and centering the mesial palatal cusp in the opposing central fossa.

[0131] In FIG. 18 a schematic diagram of a vestibular displacement device D13 can be seen.

[0132] The device D13 comprises a ring 1112 secured to the first molar, for example glued to the molar M, so that the molar M and ring 1112 are fixed together in movement. A tubular housing 113 having an axis perpendicular to the occlusal plane is secured to the medial or palatal surface of the ring 1112. The tubular housing 113 is positioned on the ring 1112 so as to be located near the mesial palatal cusp when in position on the molar.

[0133] Furthermore, the device comprises an element 1114 intended to be fixed in the patient's mouth, called "fixation element", i.e. a bone anchor, formed by a rod, the first end 1114.1 of which is intended to be fixed to the palate bone. For this purpose, the first end 1114.1 comprises a loop for receiving a screw that is screwed into the palate. The second end 1114.2 of the rod 1114 forms a pin 115 configured to remain in the tubular housing 113. The rod 1114 is intended to be immobile relative to the palate.

[0134] The pin 115 and the tubular housing 113 form a hinge A2 with a fixed axis of rotation X2 that is substantially parallel to the natural axis of rotation of the molar tooth passing through the palatal root and the mesial palatal cusp lodged in the opposing fossa. The axis X2 of the hinge A2 is located as close as possible to the natural axis of rotation of the molar tooth.

[0135] Furthermore, the device D13 comprises a means 1118 configured to apply a force F to the molar on the vestibular side so as to have a distal rotational movement.

[0136] In this example, the ring may be similar to the ring described in EP 0 689 403 and in the publication "De Baets, J.: Interception of the Pseudo-Class I using the rotational headgear tube, J. Clin. Orthod. 29:244-256, 1995" and shown in FIG. 19.

[0137] The ring comprises, on its vestibular side, a part 1154 rotatably mounted relative to the ring 1112 about an axis perpendicular to the occlusal plane. A means 1118 for exerting a distal force is fixed to the part 1154 so as to exert a distal force on the molar to which the ring is attached. This distal force is transmitted to the molar, causing it to pivot backwards. The part 1154 and / or the ring 1112 are shaped such that the force exerted by the means 1118 remains substantially the same during rotational displacement of the tooth.

[0138] The means 1118 may be extra-oral. The traction force is applied by an elastic band attached to the patient's skull or nape.

[0139] The means 1118 may be intra-oral. It may comprise a spring or elastic body fixed at one end to an interdental bone anchor or an anchor in the buccal bone and at the other end to the transfer site 1154.

[0140] In Fig. 20A one can see a schematic view of an intraoral means 1118 with fixation to the cheekbone. This means comprises a bracket 1118.1 fixed to the cheekbone and to which a hook 1118.2 is attached, and a rod 1118.3 attached by one end to the moving part 1154 and at the other end to the hook 1118.4. Furthermore, the means 1118 comprises a spring 1118.5 attached in tension between the hooks 1118.2 and 1118.3. The tension force exerted by the spring 1118.5 is converted into a centrifugal thrust force.

[0141] In FIG. 20B one can see an embodiment variant in which the means 1118' applies the thrust force directly. For example, the means 1118' comprises a bar and a compression spring R or a piston. The bar can be slidably attached and fixed to a bracket 55, for example glued to one or more premolars or milk molars or attached between the premolars by a fixing screw. The bar comprises a spherical end that enters a canal fixed by a ring, the axis of which is directed outwards and parallel to the occlusal plane, so that when the sphere enters the canal, the molar is rotated. An annular linear connection is provided between the rod and the ring. Furthermore, the device comprises a bar between the anchor 16 and the bracket 55 fixed to the premolar, fixing the premolar and avoiding the parasitic effect of the reaction force of the spring.

[0142] According to one variant shown in Fig. 20C, the impetus is provided by two magnets MG, which repel each other, instead of a compression spring. For example, one magnet is fixed to a bracket 55 and the other is attached to a rod. Furthermore, the device comprises a bar between the anchor 16 and the bracket 55 fixed to the bicuspid tooth, which fixes the bicuspid tooth and prevents the parasitic effect of the repulsive force due to the magnet fixed to the bracket.

[0143] In Fig. 21 one can see a vestibular displacement device D14 according to another embodiment, in which a fixing element 1214 is intended to be fixed to one or more premolar or deciduous molar teeth. For example, a ring or bracket 56 is bonded to one or more premolar teeth, the fixing element comprising a rod to which is attached a pin 115 housed in a housing 113 of a ring 1212 fixed to a molar tooth.

[0144] The means for applying centrifugal force 1118 is similar to that described with respect to device D13.

[0145] In FIG. 22, another example of a vestibular displacement device D15 can be seen which, in addition to applying distal rotation to the molar, can also apply distal or mesial translation, allowing the mesial palatal cusp to be returned to the opposing fossa.

[0146] In this example, the appliances are fixed to adjacent teeth.

[0147] In this example, a bracket 58 fixed to an adjacent tooth includes two fixed collar-type supports 60 aligned to fix the orientation of the rod 1314 and allow the rod 1314 to slide. The rod 1314 carries a pin 115.

[0148] Means are provided for ensuring axial fixation of the rod 1314, such as, for example, a screw 1316 passing through one or both collars.

[0149] A translation spring 62 is mounted around the rod 1314 between one of the collars and a slide 64 slidably mounted between the two collars. The translation spring 62 pushes the slide 64 fixed to the rod 1314, causing the rod 1314 to slide and resulting in a distal translational movement of the pin 115 housed in the housing 113. When a mesial movement is desired, a spring is attached to the slide 64 and the support 60. By stretching the spring, the slide 64 fixed to the rod 1314 causes the rod 1314 to slide and resulting in a mesial translational movement of the pin 115 housed in the housing 113.

[0150] Preferably, at least one of the two parts has a rectangular or square cross section to avoid relative rotation of the two parts about their axis.

[0151] The means for applying centrifugal force 1118 is similar to that described with respect to device D18.

[0152] In FIG. 23A, another example of a vestibular displacement device D16 can be seen that can apply distal rotation to the molars to apply distal or mesial translation that also allows the mesial palatal cusps to be repositioned into the opposing fossa.

[0153] The device D16 comprises a fixation element 1414 with a first part 1414.a, which is a sleeve intended to be fixed to the palate bone, and a second part 1414.b formed by a rod carrying a pin 15 and sliding in the first part 1414.a (sleeve). A screw 66 makes it possible to fix the rod 1414.b in the sleeve 1414.a.

[0154] The spring 68 is mounted in compression between the first portion 1414.a and the second portion 1414.b.

[0155] Furthermore, the device D16 comprises means for loading the translation spring 68. In this example, these means comprise a slide 70 slidably mounted on the rod 1414.b between the molar M and the fixed sleeve 1414.a. The translation spring 68 presses against the slide 70 fixed to the rod 1414.b, causing the rod 1414.b to slide and resulting in distal translation of the pin 115.

[0156] The slide 70 includes a screw 72 which axially secures the slide 70 to the second portion 1414.b and determines the load level of the spring 68.

[0157] Preferably, the first portion 1414.a and the second portion 1414.b have, for example, a square or rectangular cross-section and are rotationally fixed relative to each other.

[0158] The means for applying the centrifugal force are similar to those described with respect to device D13.

[0159] In FIG. 23B one can see a variation of the device of FIG. 23A, where the spring is replaced by two magnets MG which repel or attract each other.

[0160] As a variant, the pin or housing may be supported by a bracket that is bonded to the tooth by resin. Conveniently, the bracket is manufactured by additive manufacturing, also known as 3D printing.

[0161] The palatal and vestibular displacement device according to the invention can be manufactured by assembling parts by welding, screwing or gluing, and each part may be manufactured by cutting and machining. As a variant, the device can be at least partially fabricated by additive 3D manufacturing.

[0162] It will be understood that in all example embodiments, the pin can be carried by a rod or a ring and the housing can be carried by a ring or a rod. Additionally, all example embodiments include a rod that can be fixed to the palate bone or to one or more adjacent teeth, preferably either the bicuspids or the bicuspids and the primary molars.

[0163] In the described example, the displacement device comprises two parts, one attached to the pin and the other attached to the housing, the two parts being assembled when the pin is attached to the housing when the device is placed on the patient's molars, this realization simplifies assembly. Indeed, on the one hand, the pin is fixed to the palate or to the adjacent teeth, and on the other hand, a ring or other support is fixed to the molars. As a variant, the device can be supplied to the orthodontist already assembled before installation.

[0164] It will be appreciated that any means capable of exerting a rotational torque or translational force falls within the scope of the present invention.

Claims

1. 1. A device for the displacement of a maxillary molar (M) with a mesial palatal cusp, comprising: a support (12) intended to be fixed to said maxillary molar (M); a rod (14) with a first end (14.1), said first end intended to be fixed to the palate bone or to at least one tooth adjacent to said maxillary molar (M) such that said rod has a given position relative to said maxillary molar (M) when said device is in place; a rotation hinge (A1) between the support (12) and the rod (14), with an axis of rotation (X1) fixed relative to the rod (14) and intended to be perpendicular to the occlusal plane, said axis of rotation (X1) intended to be located near the mesial palatal cusp of the maxillary molar (M); means configured to apply a force capable of rotating said maxillary molar (M) around said axis of rotation (X1) either to the palatal surface of said molar or to the vestibular surface of said molar, such that said maxillary molar (M) has a distal rotation; An apparatus comprising:

2. 2. The displacement device according to claim 1, wherein the rod (14) comprises a pin (15) intended to form the axis of rotation (X1) and the support (12) comprises a housing (13) for the pin (15), or the support comprises a pin intended to form the axis of rotation and the rod carries a housing for the pin, the assembly of the pin and the housing forming the rotation hinge.

3. 3. The displacement device according to claim 2, wherein the means configured to apply a force capable of applying a rotation to the palatal surface of the maxillary molar (M) comprise at least one torsion spring (19) comprising a coil and two radially extending strands, the coil (20) being attached to the pin, one strand (22.2) being fixed to the support and the other strand (22.1) being fixed to the rod (14), the attachment of the other strand (22.1) to the rod (14) causing the loading of the spring.

4. 4. The displacement device according to claim 3, wherein the housing has a lateral opening across its entire height to enable the coil to be positioned by lateral displacement of the spring, the housing having a lateral slot for passing the strand attached to the support.

5. 3. The displacement device according to claim 2, wherein the means configured to apply a force capable of applying a rotation to the palatal surface of the maxillary molar (M) comprises a tension spring fixed by a first end intended for the palatal bone or intended to be fixed to one or more adjacent teeth and fixed to the support at a position different from the pivot hinge.

6. 3. The displacement device according to claim 2, wherein the means configured to apply a force capable of rotating the maxillary molar (M) to the palatal surface of the molar comprises a tension spring attached around the rod and fixed by a first end to the rod on the first end side of the rod, the device further comprising a bar having one end sliding along the rod and one end fixed to the support at a position different from the pivot hinge, the second end of the spring being fixed to the end of the bar sliding on the rod.

7. 2. The displacement device according to claim 1, wherein the rod is intended to form the axis of rotation and comprises a pin arranged near the mesial palatal cusp of the maxillary molar, and the means configured to apply a force capable of rotating the maxillary molar (M) to the palatal surface of the molar comprise at least one torsion spring (19) comprising a coil and two strands, the coil (20) being attached to the pin, the device being configured to be connected to the support by one strand of the torsion spring.

8. 3. The displacement device according to claim 1 or 2, wherein the means configured to apply a force capable of rotating the maxillary molar (M) to the vestibular surface of the molar comprises a part rotatably articulated on the support, said part being located on the vestibular surface of the molar, and elastic means or repelling magnets exert a force on said articulated part.

9. 9. The displacement device of claim 8, wherein the means configured to apply a force to the vestibular surface of the molar is configured to be fixed between two teeth or to the cheekbone, or is extra-oral and fixed to the patient's skull or neck.

10. means configured to apply a force capable of displacing said maxillary molars in translation; The displacement device according to any one of claims 1 to 7, comprising:

11. 11. The displacement device of claim 10, wherein the means configured to apply a force capable of displacing the maxillary molars in translation comprises translational springs or magnets oriented relative to each other so as to repel or attract each other depending on the desired effect.

12. 12. The displacement device of claim 11, wherein the rod comprises a first part and a second part configured to slide relative to one another, and the translation spring is mounted on the rod between the first part and the second part, or the magnet is mounted on the first part and the second part.

13. The displacement device of claim 12 , wherein the first and second portions have cross sections that prevent relative rotation about their axes.

14. 14. The displacement device according to claim 12 or 13, wherein the spring is fixed by one end to the first part and by another end to the second part, and the relative position of the first part and the second part allows for compression or tension of the translational spring.

15. A shroud that covers at least the translation spring and forms the first portion or the second portion. The displacement device according to any one of claims 11 to 14, comprising:

16. The displacement device according to any one of claims 1 to 15, wherein the support is a ring intended to be attached around the maxillary first molar and / or the displacement device comprises a bracket fixed to one or more teeth adjacent to the maxillary first molar, and to which the first end of the rod is fixed.

Images