GB2258616A - Orthodontic attachments - Google Patents

Abstract

An orthodontic attachment comprises a face bow (1) or a component (25) for use with a face bow (21), having a loop (11, 12, 13 or 11a, 12a, 13a) for contact with the occlusal surface of a tooth. An extension (3) of the loop or an end (23) of the face bow carrying the attachment lies buccal of the tooth and engages a headgear tube (6) secured to the tooth. The attachment is able to provide buccal root torque. Advantageously, the shape of the face bow is such as to provide a rounded, safe end (9) extending beyond said extension (3). <IMAGE>

Description

Title: Orthodontic appliance DESCRIPTION This invention relates to an orthodontic appliance, constructed as a face bow or a component for use with orthodontic face bow.

Extra oral traction can be delivered to fixed or removable orthodontic appliances via a face-bow. The intra-oral part of the face-bow is generally inserted in tubes mounted on molar bands on fixed appliances, or in the case of removable appliances, the tubes are incorporated in the structure of the appliance. There are two major problems with the standard design of facebow which have been encountered: Firstly, there is the risk of injury from the free end of the inner arms of the face bow should the face bow become detached from the headgear tubes during use.

Secondly, the standard design of face-bow is unable to prevent rotation of the upper molar teeth in the coronal plane (buccal crown torque) when forces are applied with high pull headgear. This is because the distance between the applied force and the centre of resistance of the molar tooth to which the headgear tube is attached causes a torquing moment of force to be set up and because the system allows free rotation of the headgear tube about the portion of the face bow inserted therein without being able to deliver a torquing moment in opposition to that which has been induced.

Safe ended face-bows have been produced which use the standard design of headgear tube (ie. with circular cross-section), but are not designed to produce buccal root torque. On such a face bow a guard is constructed using a blunt loop of wire which extends distally to the end of the wire which inserts in the headgear tubes of the appliance. This guard is a buccally mounted safety loop and it is intended to reduce the risk of injury to soft tissues from penetration by the distal tip or tips of the inner arms of the face bow.

Methods of applying buccal root torque with other designs of face-bow have been devised, but a torque face bow is not known which has a device to guard soft tissues from the tips of the inner arms of the face bow in the same way as have been devised for safe ended face bows as described above. Face bows capable of applying buccal root torque so far described require modified headgear tubes, eg. with insertion of the face bow into vertical tubes.

Other problems with face bows are described herewith: A face bow which does not enter between the occlusal surfaces of the teeth is liable to be displaced vertically should it accidentally become detached from the headgear tubes. As a result it could come into contact with the gingival tissues or alveolar mucosa, and if with sufficient force a laceration or penetrating injury might result to the tissues medial to the tips of the inner arms of the face bow. It seems possible that this eventuality might occur not only with standard face bows, but also with those with a buccally mounted safety loop, or those used with the vertical tube headgear.

Face bows generally have little flexibility within the occlusal plane which if present to a greater degree could allow easy insertion of the face bow into the headgear tubes in cases where the upper molar teeth have rotated bucco-mesially. One embodiment of this invention allows added flexibility in this direction, giving the opportunity for improved rotational control of the upper molar teeth.

The present invention aims to remedy the drawbacks of currently known face bows by offering an appliance configuration for use with the standard design of headgear tubes, which provides one or more of the following advantages:1. protection of soft tissues by a safe ended device, 2. the facility to apply buccal root torque, 3. resistance to vertical displacement should it become detached from the headgear tubes within the mouth, and 4. easier engagement of mesially rotated molar teeth.

According to the present invention, an orthodontic attachment comprises a face bow or a component for use with a face bow having means to make contact with the occlusal surface of at least one tooth or another part of the tooth or appliance which lies palatal or occlusal to a headgear tube with which an end of the face bow is entrant in use.

Such contact enables the attachment to provide buccal root torque, for example to one or more upper molar teeth. Thus preferably the attachment has a part or parts which form the connection with the headgear tube on the buccal surface of the tooth, extends in the occlusal plane in the palatal direction, and preferably then back in the buccal direction. The end is preferably of standard circular cross-section to be received in a standard headgear tube, ie. a tube whose axis for insertion of the face bow end is substantially in the occlusal plane. With this invention the standard headgear tube of circular cross-section, mounted in the conventional position with its long axis approximately in the occlusal plane and approximately parallel to the general line of dental arch can be used.

A blunt loop of wire or other blunt edged shape of wire or another material (possibly plastics for example) extends distally at least to the end of the face bow (typically wire) which inserts in the headgear tubes of the appliance. This is advantageous in helping to protect the soft tissues from penetrating injury should the appliance be detached from the headgear tubes. The attachment may be an integral part of a face bow, and hence forms part of the inner arms of the face bow, or it may part of an intra-oral appliance without being permanently fixed to a face bow. In such an embodiment where the orthodontic attachment forms part of a face bow it constitutes a safe ended, torque face bow. When the orthodontic attachment is part of an intra-oral appliance without being permanently fixed to a face bow, it constitutes a molar torquing device.The orthodontic attachment may be used to carry other auxiliary devices.

In a first embodiment end portions of the inner arms of the face bow are formed by a single piece of wire which is bent to provide both the end which inserts in the headgear tube, the portion which contact the tooth (direct or indirectly) to give buccal root torque and the portion which acts as a guard by extending distally to the end which inserts in the headgear tube.

When the orthodontic attachment is formed from such a bent piece of wire, flexibility in the occlusal plane may be used to apply rotational forces about the axis of the tooth engaged.

In another embodiment each of the members or components which provides the end to insert in the headgear tube, the portion which provides buccal root torque or the guard portion could be made from separate pieces of wire or other material, but fixed together to produce the same essential configuration of components to achieve the same effect as the first embodiment.

Alternatively a component may be added to the standard design of face bow to produce the same essential configuration of components, eg. combination of features to achieve the same effect as the first embodiment. Such a component which may be releasable is nevertheless secured non-rotatably with respect to the face bow where it is to provide buccal root torque. The orthodontic appliance according to the preferred embodiment of the invention is safe ended, and can provide buccal root torque and can be inserted into a standard design of headgear tube.

The present invention will now be described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a first embodiment of torque face bow according to the invention, Figure 2 is a side view of one end of the torque face bow of Figure 1, Figure 3 is an end view of one end of the torque face bow of Figures 1 and 2, Figure 4 is a plan view of a second embodiment of torque face bow according to the invention, Figure 5 is an end view of one end of the torque bow of Figure 4, and Figure 6 is a plan view of one half of a standard face bow modified according to the present invention.

Referring firstly to Figures 1 to 3, a first embodiment of the present invention is illustrated in the form of a torque face bow and comprise a generally U-shaped wire 1 having respective straight end parts 3 of circular cross-section to be received in headgear tubes which would be securely located to a patients teeth with its bore in a generally horizontal plane, eg.

a selected upper molar to opposite sides of the palate.

A headgear tube is illustrated in dotted outline at 6 in Figures 2 and 3. The end of the wire faces distally towards the back of the mouth.

From the end part the wire bends thorough substantially 180 degrees at 9 to return at 10 substantially parallel to the end part 3 and with the end and return being disposed substantially parallel and adjacent the surface of the tooth. The return extends beyond the end of the end part 3 to thereby act as a guard preventing injury by the end part. The wire return then turns in the palatal direction (say through approximately 90 degrees) to extend in the occlusal plane at 11 over the teeth, then being bent (through approximately 90 degrees) in the same plane to extend forwardly (ie. in the Mesial direction) at 12 and then bent again (through approximately 90 to extend) at 13 in the occlusal to the buccal side of the tooth where it is bent through approximately 90 to extend at 14 forwardly and upwardly before continuing along the teeth to the forward part of the bow.Normally the two halves of the bow will be a mirror image. Wing-like wire arms 15, 16 are carried by the face bow in a conventional manner. Other of the teeth may have attachments in the form of brackets with which the bow cooperates in use.

The torque inducing portions of the face bow are provided by the possibility for interaction between the end 3 and the parts 11, 12, 13 which engage the occlusal part of the tooth. Those parts 11, 12 and 13 and the rearward extension of limb 10 provide the guard function.

Referring now to Figures 4 and 5, an alternative embodiment of torque face bow is illustrated. It is similar to the first embodiment in using a single wire to form the bow 1 and like reference numerals have been used for corresponding parts and references with an apostrophe denote modified parts. Thus the bend 9' to the return 10' is directed upwardly, ie. away from the occlusal surface such that the return provides a more extensive buccal guide before first turning downwardly at 10a and then inwardly to enter the occlusal plane with parts 11, 12 and 13 as previously.

Referring now to Figure 6, there is illustrated an alternative embodiment of the invention made up from a standard U-shaped wire face bow 21 (only half shown) to which is attached a member to provide direct contact with an occlusal surface of the tooth or to otherwise apply a buccal torque by contact with another component contacting the tooth say at the palatal side. That member comprises a loop of wire fixedly secured to the face bow at 24 inset from the end 23 of the face bow which is to be received in the headgear tube and providing a loop 25 to contact the occlusal surface of the tooth parts lla, 12a, 13a and extending on the buccal side of the tooth 10a. In other words it has the various bends and returns described with respect to the first or second embodiments starting from forwardly of the end 3.

As an alternative the member of Figure 6 may be a separate component arranged for attachment to the face bow in a non-rotatable manner.

The invention has been described above with particular reference to its application to upper teeth, but it will be understood that the invention -is not to be seen as limited to an upper tooth face bow and that it can also be embodied in a lower tooth face bow or component therefor.

Claims (14)

1. An orthodontic attachment comprising a face bow or a component for use with a face bow, having means to make contact with the occlusal surface of at least one tooth or another part of the tooth or appliance which lies palatal or occlusal to a headgear tube with which an end of the face bow is entrant in use.

2. An orthodontic attachment as claimed in Claim 1 in which the prescribed contact enables the attachment to provide buccal root torque, for example to one or more upper molar teeth.

3. An orthodontic attachment as claimed in Claim 1 or 2 comprising a part or parts which form the connection with the headgear tube on the buccal surface of the tooth, extends in the occlusal plane in the palatal direction, and then back in the buccal direction.

4. An orthodontic attachment as claimed in any of Claims 1, 2 or 3 comprising an end of circular crosssection to be received in a standard headgear tube.

5. An orthodontic attachment as claimed in Claim 4 wherein said end is a blunt loop of wire or other blunt edged shape of wire or another material extends distally at least to the end of the face bow which inserts in the headgear tubes of the appliance.

6. An orthodontic attachment as claimed in Claim 5 in which said another material is a plastics material and said face bow is typically wire.

7. An orthodontic attachment as claimed in any one of the preceding claims wherein said face bow comprises inner arms and said orthodontic attachment is an integral part of a face bow, and hence forms part of the inner arms of the face bow.

8. An orthodontic attachment as claimed in any one of the preceding claims wherein said orthodontic attachment is part of an intra-oral appliance without being permanently fixed to a face bow.

9. An orthodontic attachment as claimed in any one of Claims 1 to 8 in which said orthodontic attachment is used to carry other auxiliary devices.

10. An orthodontic attachment as claimed in Claim 7 or 9, in which the inner arms of the face bow have an end portion formed by a single piece of wire which is bent to provide both the end which inserts in the headgear tube, the portion which contacts the tooth (direct or indirectly) to give buccal root torque and the portion which acts as a guard by extending distally to the end which inserts in the headgear tube.

11. An orthodontic attachment as claimed in Claim 10 wherein said orthodontic attachment is formed from a bent piece of wire such that flexibility in the occlusal plane is used to apply rotational forces about the axis of the tooth engaged.

12. An orthodontic attachment as claimed in any one of Claims 1 to 6 in which the orthodontic attachment comprises members or components which provide said end to be received in the headgear tube, and wherein a portion which provides buccal root torque or a guard portion is/are made from separate pieces of wire or other material which are fixed together.

13. An orthodontic attachment as claimed in Claim 1 in which said component is secured non-rotatably with respect to the face bow where it is to provide buccal root torque.

14. An orthodontic attachment substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 5 or Figure 6.