US3235965A

US3235965A - Orthodontic torquing appliance

Info

Publication number: US3235965A
Application number: US263209A
Authority: US
Inventors: Richard J Muir
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-03-06
Filing date: 1963-03-06
Publication date: 1966-02-22
Anticipated expiration: 1983-02-22

Description

Feb. 22, 1966 MUlR 3,235,965

ORTHODONTI C TORQUING APPLIANCE Filed March 6, 1963 2 Sheets-Sheec 1 Feb. 22, 1966 R. J. MUIR 3,235,965

ORTHODONTIC TORQUING APPLIANCE Filed March 6, 1963 2 Sheets-Sheet 2 Q \H 1N VEN TOR Fave 4 40 (fl/0M United States Patent Ofilice 3,235,965 Patented Feb. 22, 1966 3,235,965 ORTHQDONTIC TORQUING APPLIANCE Richard J. Muir, 12 Oak Road, Santa Cruz, Calif. Filed Mar. 6, 1963, Scr. No. 263,209 4 Claims. (CI. 3214) This invention relates to orthodontic torquing appliances, and more particularly to a torsion spring mechanism mountable to an arch wire in orthodontia.

In orthodontia, in which misalignment of teeth is corrected by application of controlled forces to selected teeth, it often occurs that a single orthodontic technique is not well :adapted to correct the misalignment of teeth in a particular patient. Each orthodontic technique, such as the edgewise, lightwire (Begg), universal, or twin-wire technique, is best adapted to correct a specific type of misalignments or to apply force in a particular manner. Each of these techniques, however, provides that the force applied to a given tooth has a reaction on an adjacent tooth. In the majority of situations this is desired and judicious selection of the action and reaction of the forces is relied upon to move the teeth to correct for misalignment. For example, in the Begglightwire technique a round arch wire is formed into loops which are disposed at selected locations relative to the teeth. The loops act as springs, the alignment of a loop :and the degree of defiection from a relaxed or unstressed condition determining the nature of movement of the teeth between which the loop is disposed. Similarly, in the edgewise technique a square arch wire is engaged in rectangularly configured slotted brackets secured to selected teeth, the arch wire being torqued to impart force to the brackets.

In each of these methods, however, it is not readily possible to apply controlled force to :a single tooth to cause the tooth crown to move posteriorly in a pivoting motion relative to the root of the tooth. In cases where incisor teeth tilt lingually, the limitations of existing orthodontic appliances are especially restrictive. The present invention provides simple, effective and efficient means whereby a single tooth may be moved pivotally substantially independently of adjacent teeth. The apparatus of the present invention is especially effective in correcting lingual tilting of crowns of incisors.

Generally speaking, the present invention provides an orthodontic torquing appliance which is engagable with an arch wire disposed labially of the tooth. The applitance comprises a length of wire configured at each of a pair of spaced apart ends for loosely circumferentially engaging the arch wire distally of the tooth along an axis of the appliance. The appliance axis is coextensive with the arch wire over the length of the appliance. The wire defines torque output means intermediate of its ends for engaging the tooth apically of the tooth from the appliance axis. The wire adjacent opposite extents of the torque output means defines a plurality of coils which engage the arch wire along the axis. The wire ex tends in opposite directions distally from the coils to the ends of the wire and defines torque input arms substantially parallel to the appliance axis.

The above mentioned and other features of the present invention are more fully described in the following detailel description of the invention, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a plan view of a human maxillary denture showing the torquing appliance of the present invention installed on an orthodontic arch wire;

FIG. 2 is a quartering side elevation view of the installation shown in FIG. 1;

FIG. 3 is an idealized cross sectional view taken along line III-III of FIG. 1 showing the torquing appliance mounted to an arch wire installed according to the edgewise technique;

FIG. 4 is an enlarged elevation view of a preferred embodiment of the torquing appliance according to the present invention adapted for use in the edgewise technique of orthodontia;

FIG. 5 is a fragmentary elevation view of an end of a second preferred torquing appliance adapted for use in the edgewise technique of orthodontia;

FIG. 6 is an elevation view of an end of a third pre ferred torquing appliance for use in conjunction with the lightwire technique of orthodontia; and

FIG, 7 is an elevation view of a fourth preferred embodiment of the present invention adapted for use with the edgewise technique in orthodontia of the mandibular denture.

Referring initially to FIGS. 1 and 2, maxillary orthodontia 10, incorporating a torquing appliance 11 according to the present invention, is illustrated. The auxiliary, or upper jaw, denture includes central incisors 12 and 13,

lateral incisors

14 and 15, cuspid teeth 16 and 17,

first bicuspids

18 and 19, second bicuspids 20 and 21, and first and second molars 22 through 25, respectively. The crowns of the 1st molars, and all teeth between the first molars, are banded, as by band 26 on central incisor 12, to mount orthodontic edgewise-type arch wire supporting brackets 27. An arch wire anchoring bracket 28 is mounted to the bands engaged with the first molars. An arch wire 29 is engaged circumferentially and anteriorly of the denture between the

first molars

22 and 23 and has its opposite ends engaged in the anchoring brackets; the arch wire is disposed in supporting brackets 27 intermediate of its ends.

In the orthodontia illustrated in FIGS. 1 and 2, the arch wire is circularly cross sectioned to provide an arch wire according to the lightwire technique (see FIG. 3). The arch wire is engaged in a rectangularly contoured slot in each of brackets 27 so that a torque imposed on the arch wire is transferred to the teeth so that selected teeth are moved relative to adjacent teeth. The arch wire is ligated to each supporting bracket 27 by fine wires engaged to the cleat-like configuration of the brackets. The ligation technique is conventional in orthodontic practice. but the ligation wires are not shown in thhe accompanying drawings for the purpose of clarity of illustration.

FIG. 4 illustrates a preferred embodiment of the torquing appliance according to the present invention. The appliance is fabricated from a length of metallic resilient wire. The wire preferably has a diameter of about .012 to .014 inch and preferably is fabricated from stainless steel. The wire has a pair of ends 31 and 32 spaced apart distally of the midlength or mesial portion of the wire when the appliance is installed. The ends of the wire are aligned along an axis 33 which preferably is coextensive with arch wire 29 along the elongate extent of the appliance. As shown in FIG. 4, a plurality of return-bend torque output means '3437 are formed in the wire intermediate the ends of the wire. The torque output means are also known as anterior loops since they engage the anterior or labial surfaces of the teeth acted on by the appliance. Each return-bend torque output means comprises a substantially U-shaped bend in the wire, each torque output means having diverging legs 38 and 39 and a preferably straight portion 40 parallel to axis 33 joining the legs. Portion 40 is provided for engaging the labial surface of the tooth opposite which it is disposed apically of the arch wire, i.e. toward the gingiva or gum from the arch wire. The legs of each torque output means terminate in a plurality of tor'sionally

resilient coils

41, 42, 43, 44, and 45.

Coils

42, 43, and 44 are disposed intermediate torque output means 34-37; torsion coils 41 and 45 are disposed at opposite ends of the plurality of torsion output means. The torsion output means extend in the same direction from axis 33 to have the straight labial surface engaging portions 40 disposed coaxially parallel to axis 33. The legs of each torsion output means converge extending from the respective torsion coils to the labial surface engaging portions of the return-bend sections of wire 30. The internal diameter of each of the plurality of coils 41-45 is greater than the maximum cross-sectional dimension of the arch wire so that, when the arch wire is disposed through coils 41-45, the coils loosely and circumferentially engage the arch wire as fulcrums for the respective torque output means and permit movement of the appliance relative to the arch wire.

Torque input means 46 and 47 extend distally laterally from the coils 41 and 45, respectively, away from the torque input means toward the end of the wire. In the embodiment of the invention illustrated in FIG. 4, the torque input means comprise torque arms which are disposed parallel to, but are spaced apart from, axis 33 of the appliance. Each torque input arm terminates in an arch wire anchor means 48, 49, respectively, at the ends of the wire. Preferably, the anchor means are provided in the form of a pair of coils in the wire. The coils of the anchor means are of the same internal diameter as each of the coils in the pluralities of coils 41-45 so that the anchor means coils loosely and circumferen-.

tially engages the arch wire and permits relative movement between the arch wire and the appliance.

Appliance 11 is manufactured by any convenient method, such as upon a wire bending machine, to provide the planar configuration illustrated in FIG. 4. After the device has been formed, it is heated in an oven to stress-relieve the wire. The appliance is then ready for installation upon an arch wire. The arch wire is inserted through coils 41-45 and 48, 49 axially of the appliance. The arch wire, with the appliance attached, is then ligated to the arch wire supporting and anchoring brackets with the torque output means of the appliance being disposed adjacent the teeth which are desired to be moved pivotally about their roots.

It was mentioned above that the present invention is particularly effective in correcting lingual tilting of incisors. When the arch wire and the appliance attached are mounted to the brackets in a situation similar to that illustrated in FIG. 1, the torque output means of the appliance are disposed apically of the arch wire anteriorly of the incisor teeth. Accordingly, the torque input arms 46 and 47 are disposed toward the occlusal areas of the cuspid and first bicuspid teeth distally of the incisors. The anchor means of the appliance are disposed in the spaces between the first and second bicuspids. As the arch wire is curved to conform to the arch of the denture and the output loops are accordingly forced out of the plane of the arch, torque is imposed upon the appliance primarily through the torque input arms which normally tend to be disposed on the convex side of the arch Wire. The occlusal portions of the cuspid and first bicuspid teeth prevent the input torque arms from rotating into the concave aspect of the arch. The forces imposed in the Wire of the appliance induce the torque output arms to engage the labial surfaces of the incisor teeth apically of the arch wire. The reaction of this torsional force is a torque F (see FIG. 3) which induces the root of the engaged tooth to move posteriorly about its crown.

Orthodontic techniques are predicated upon the application of controlled forces to selected teeth. The appliance provided by the present invention permits controlled forces to be applied to the incisor teeth to correct for lingual tilting. The amount of torque imposed upon the teeth may be regulated by the spacing between coils 4145 along axis 33. To increase the imposed torque, the distance between the distal ends of the appliance is decreased to move together coils 4145 to increase the lateral distance between portions 40 of the return-bend arms of the torque output means and axis 33. The appliance is then stress-relieved, either by the orthodonti'st or by the manufacturer of the appliance. Similarly, the imposed torque may be decreased by moving the distal ends of the appliance apart from one another to reduce the effective torque arms of the torque output means.

If it is assumed that central incisor 13 (illustrated in FIG. 1) has its root portion protruding farther anteriorly of the denture than the immediately adjacent teeth, torque output means 36 disposed adjacent tooth 13 will engage the tooth before the torque output means disposed opposite the adjacent teeth engage the adjacent teeth. Accordingly, central incisor 13 is moved pivotally about the arch wire until it is aligned with the adjacent teeth. If desired, the roots of

teeth

12, 13, 14, and 15 may be pivoted further posteriorly about their crown-s through continued application of forces from the appliance. In many instances, however, only a single tooth is to be moved by the appliance of the present invention. In such instances the appliance may include only one return-bend torque output means. Alternatively, where a standard appliance is provided, the selected torque output means may be deformed out of alignment with portions 40 of adjacent torque output means toward the tooth so that only the deformed return-bend torque arm engages a tooth; the other arms do not engage their teeth as the selected tooth moves under applied force. It is noted at this point that the appliance may be used on teeth other than incisors.

It was mentioned above that the internal dimensions of coils 41-45 and 48, 49 provide for movable engagement of the appliance with the supporting arch wire. Such movement is required to allow the appliance to exert continuing force upon selected teeth while the selected teeth move through considerable distances in the denture. If the ends of the appliance Were secured to the arch wire, as by soldering, the amount of torque which may be applied to the incisors normally is restricted and the amount of movement of the torque output means angularly about the arch wire is limited. As a result the protruding incisors may move only a small distance before all of the stored force in the appliance is released. In other instances however the torque input arms may be prestressed by soldering the anchor means in position more toward the adjacent teeth than normally to increase the output torque, as where friction between the appliance and arch wire must be overcome.

The foregoing description has presented a mechanism which may be used to apply a substantially constant torquing force. The amount of torquing force is not altered by the response of the teeth to the force applied. As a result, the present invention eliminates the repeated fittings which are required when other orthodontic techniques are used by themselves. The present invention also provides that the force is applied continuously. In the edgewise technique, for example, the force is applied initially at greater strength than after the teeth have moved in response to the applied force. It is therefore necessary, if continued movement is desired in the edgewise technique, to apply a second arch wire. The applied force imposed by the second arch wire decays rapidly as the teeth move in response to applied force. The continuously non-cyclic applied force provided by the present invention is particularly significant in that it overcomes the problems associated with cyclic applications of force to the teeth undergoing orthodontia.

The specific configuration of apparatus illustrated in FIG. 4 is adapted for use with the edgewise technique wherein the arch wire is disposed centrally of the supporting brackets on hands 26 (see FIG. 3). It is therefore necessary for the torque arms of torque input means 46 and 47, in order to be disposed occlusally of the arch wire, to be offset from the axis of the appliance in order to be disposed below the arch wire supporting brackets. The' ends of the arch wire brackets. In a presently preferred form of appliance 11 the distance between axis 33 and portions is 0.115 inch while the distance of torque input arms 46, 47 from the axis is .O8.09 inch. The 0.115 inch dimension is especially preferred since it is not uncommon for the gingiva of a child undergoing orthodontia to depend so far down a tooth that it is necessary to cut the gingiva away to band the tooth. It is therefore desirable not to have the torque arm extend unduly far apically of the arch wire even though the greatest torque arm possible is desired for mechanical purposes. In the same presently preferred embodiment as mentioned above, the extent of portions 40 of torque output means 35 and 36 is 0.187 inch while the extent of the corresponding parts of output means 34 and 37 is 0.125 inch.

FIG. 5 illustrates an appliance according to the present invention adapted for use in conjunction with the lightwire technique. In the lightwire technique the arch wire receiving notches in the supporting brackets are disposed either gingivally or occlusally of the brackets rather than through the central portion of the bracket. It is therefore possible for torque arm 51 of torsion input means 52 to be disposed closely adjacent axis 53 of appliance 50.

Appliance 55 (illustrated in FIG. 6) is a second preferred embodiment of the present invention adapted for use in conjunction with the edgewise technique. It was mentioned above that the anchor means of appliance 11 are disposed in the area between the first and second

bicuspid teeth

18, 19 and 20, 21, respectively. In cases where misalignment of the teeth in the denture is severe, the distance distally of the incisors to be pivoted to the space between the first and second bicuspids may be so considerable that the anchor means of a standard appliance (FIG. 4) may foul the brackets mounted to the first bi'cuspids. Appliance 55 provides a torque arm 56 having a plain or uncoiled end 57. The orthodontist may coil the end of the appliance about the arch wire at any desired location in the patients mouth to accomplish the result described above with appliance 11.

The foregoing discussion and explanation of the invention has been in conjunction with a maxillary denture. The invention, however, may be used in conjunction with a mandibular denture, i.e. the tooth arrangement in the lower jaw of a patient. In such a case, however, the torque input means and the torque output means are disposed on the same side of the axis of the appliance, rather than on opposite sides of the axis as illustrated in FIG. 4. FIG. 7 shows a mandibular form of the present invention in appliance 60 which has an axis 61 defined by a plurality of torsionally resilient coils 62 disposed between a torque output means 63 and a torque input means 64 (similar to the torque input means illustrated in FIG. 6). The mandibular appliance is installed with the return-bend torque output means 63 extending apically of the tooth from axis 61. Torque input means 64 is also disposed below the axis of the appliance and below the arch wire upon which the appliance is supported.

In many cases the degree of eruption of the tooth to be acted upon by an appliance according to the present invention is not such as to permit direct use of a standard appliance, such as that illustrated in FIG. 4. The lateral distance between arch wire 29 and the gingiva may be less than the lateral distance between axis 33 of the appliance and coaxially aligned portions 40. In such an instance, it is a simple expedient to bend the legs of the torque output means to reduce the torque arm of the output means to clear the gingiva and to bear directly upon the labial surface of the teeth.

While the invention has been described above in conjunction with specific apparatus, it should be apparent to those skilled in the art, and particularly to Orthodontists using the present invention, that the appliance described above may be modified to accommodate particular treatment situations without departing from the scope of the present invention. The foregoing description is presented merely for the purposes of explanation and example and is not to be considered as restrictive of the scope of the present invention.

What is claimed. is:

1. A structural system for effecting tilting of a persons tooth comprising, in combination, a metal band adapted to be mounted around the tooth, a bracket affixed to the band and adapted to extend anteriorly of the tooth, the bracket defining a channel in its labial aspect, an arch wire extending through the channel, means connected to the bracket retaining the arch wire in the channel, the arch wire extending laterally of the bracket to ends spaced substantially from the bracket, means for attaching respective ends of the arch wire to two other teeth spaced from said tooth, the arch wire curving arcuately between its ends, and a length of resilient wire defining intermediate its ends two groups of helical coils circumferentially of the arch wire, the groups of coils loosely circumferentially engaging the arch wire laterally of and proximate to the bracket, the resilient wire between the groups of coils defining a return-bend loop extending laterally of the arch wire, the loop having a portion substantially parallel to the arch wire spaced from the arch Wire, the resilient wire extending from each group of coils away from the return-bend. loop along and in spaced relation to the arch wire to ends of the resilient wire spaced substantially from the groups of coils, means securing the ends of the resilient wire to the arch wire, conformance of the elongate extent of the resilient wire to the curvature of the arch wire torsionally biasing the resilient wire between its ends and the groups of coils to produce torquing leverage on the tooth through engagement of said portion of the return-bend loop with the tooth when the system is in use effective to pivot'the tooth about the connection between the arch wire and the bracket.

2. A structural system for effecting tilting of a persons tooth comprising, in combination, a metal band adapted to be mounted around the tooth, a bracket afiixed to the band and adapted to extend anteriorly of the tooth, the bracket defining a channel in its labial aspect, an arch wire extending through the channel, means connected to the bracket retaining the arch wire in the channel, the arch wire extending laterally of the bracket to ends spaced substantially from the bracket, means for attaching respective ends of the arch wire to two other teeth spaced from said tooth, the arch wire curving arcuately between its ends, and a length of resilient wire defining intermediate its ends two groups of closely wound. helical coils circumferentially of the arch wire, the groups of coils loosely circumferentially engaging the arch Wire on opposite sides of and proximate to the bracket, the resilient wire between the groups of coils defining a return-bend loop extending laterally of the arch wire substantially directly from the groups of coils, the resilient wire extending from each group of coils away from the return-bend loop along and in spaced relation to the arch wire to ends of the resilient wire spaced substantially from the groups of coils, the resilient wire between the coils and the ends of the resilient wire defining torque input arms relative to the return-band loop, the resilient wire at each of its ends defining at least one coil which loosely engages the arch wire about the circumference of the arch wire to hold the ends of the resilient wire relative to the arch wire and to substantially conform the elongate extent of the resilient wire to the curvature of the arch wire, conformance of the elongate extent of the resilient wire to the curvature of the arch wire torsion-ally biasing the resilient wire at the torque input arms thereof to produce torquing leverage on the tooth through engagement of the return-bend loop with the tooth when the system is in use, the torquing leverage being effective to pivot the tooth about the connection between the arch wire and the bracket.

3. A structural system for effecting tilting selected ones of a persons teeth comprising, in combination, a metal band adapted. to be mounted around each of the selected teeth, a bracket affixed to each band and adapted to extend anteriorly of the respective selected tooth, each bracket defining a channel in its labial aspect, an arch wire extending through the channels, means connected to each bracket retaining the arch wire in the channel thereof, the arch wire extending laterally of the brackets to ends spaced substantially from the brackets, means for attaching respective ends of the arch wire to two other teeth spaced from said selected teeth, the arch wire curving arcuatelybetween its ends, and a length of resilient Wire defining intermediate its ends two groups of closely wound helical coils circumferentially of the arch wire, the groups of coils loosely circumferentially engaging the arch wire laterally of and proximate to the brackets mounted to the most widely spaced selected teeth, the resilient wire within its length between the groups of coils defining a plurality of return-bend loops corresponding in number to the number of said selected teeth and extending laterally of the arch wire, the loops being adapted to be positioned adjacent respective ones of the selected teeth and each having a portion substantially parallel to the arch wire spaced from the arch wire a distance greater than the gingival edge of the bracket, the resilient wire between each loop of the plurality defining at least one coil loosely engaging the arch wire about its circumference between the brackets, the resilient wire extending from each group of coils away from the return-bend loops along and in substantially parallel spaced relation to the arch wire to ends of the resilient Wire spaced substantially from the groups of coils, the resilient wire between the groups of coils and the ends of the resilient wire defining torque input arms relative to the return bend loops, the resilient wire at each of its ends defining at least one coil which loosely engages the arch wire about the circumference of the arch Wire to hold the ends of the resilient wire relative to the arch wire and to substantially conform the elongate extent of the resilient wire to the curvature of the arch wire, conformance of the elongate extent of the resilient wire to the curvature of the arch wire torsionally biasing the resilient wire at the torque input arms thereof to produce torquing leverage on the tooth through engagement of the return-bend loops with the selected teeth when the system is in use, the torquing leverage being effective to pivot the selected teeth about the connections between the arch wire and. the respective brackets.

4. An orthodontic appliance comprising an arch wire, and a length of resilient wire, the resilient wire intermediate its ends defining two sets of closely wound coils, the sets of coils being spaced apart from each other and loosely engaging the arch wire the resilient wire between the sets of coils defining a return-bend loop having spaced apart legs extending substantially directly from respective ones of the sets of coils to a portion of the loops spaced from the arch wire and connecting the legs of the loop, the resilient wire extending from the sets of coils away from the loop to the ends of the resilient wire, the resilient wire adjacent each end thereof at a location spaced from the adjacent set of coils defining an additional coil loosely engaging the arch wire, the resilient wire between each set of coils and the adjacent additional coil being spaced from the arch wire.

FOREIGN PATENTS 334,129 12/1958 Switzerland.

RICHARD A. GAUDET, Primary Examiner.

Claims

1. A STRUCTURAL SYSTEM FOR EFFECTING TILTING OF A PERSON''S TOOTH COMPRISING, IN COMBINATION, A METAL BAND ADAPTED TO BE MOUNTED AROUND THE TOOTH, A BRACKET AFFIXED TO THE BAND AND ADAPTED TO EXTEND ANTERIORLY OF THE TOOTH, THE BRACKET DEFINING A CHANNEL IN ITS LABIAL ASPECT, AN ARCH WIRE EXTENDING THROUGH THE CHANNEL, MEANS CONNECTED TO THE BRACKET RETAINING THE ARCH WIRE IN THE CHANNEL, THE ARCH WIRE EXTENDING LATERALLY OF THE BRACKET TO ENDS SPACED SUBSTANTIALLY FROM THE BRACKET, MEANS FOR ATTACHING RESPECTIVE ENDS OF THE ARCH WIRE TO TWO OTHER TEETH SPACED FROM SAID TOOTH, THE ARCH WIRE CURVING ARCUATELY BETWEEN ITS ENDS, AND A LENGTH OF RESILIENT WIRE DEFINING INTERMEDIATE ITS ENDS TWO GROUPS OF HELICAL COILS CIRCUMFERENTIALLY OF THE ARCH WIRE, THE GROUPS OF COIL LOOSELY CIRCUMFERENTIALLY ENGAGING THE ARCH WIRE LATERALLY OF AND PROXIMATE TO THE BRACKET, THE RESILIENT WIRE BETWEEN THE GROUPS OF COILS DEFINING A RETURN-BEND LOOP EXTENDING LATERALLY OF THE ARCH WIRE, THE LOOP HAVING A PORTION SUBSTANTIALLY PARALLEL TO THE ARCH WIRE SPACED FROM THE ARCH WIRE, THE RESILIENT WIRE EXTENDING FROM EACH GROUP OF COILS AWAY FROM THE RETURN-BEND LOOP ALONG AND IN SAPCED RELATION TO THE ARCH WIRE TO ENDS OF THE RESILINET WIRE SPACED SUBSTANTIALLY FROM THE GROUPS OF COILS, MEANS SECURING THE ENDS OF THE RESILINET WIRE ARCH TO THE ARCH WIRE, CONFORMANCE OF THE ELONGATE EXTENT OF THE RESILIENT WIRE TO THE CURVATURE OF THE ARCH WIRE TORSIONALLY BIASING THE RESILIENT WIRE BETWEEN ITS ENDS AND THE GROUPS OF COILS TO PRODUCE TORQUING LEVERAGE ON THE TOOTH THROUGH ENGAGEMENT OF SAID PORTION OF THE RETURN-BEND LOOP WITH THE TOOTH WHEN THE SYSTEM IS IN USE EFFECTIVE TO PIVOT THE TOOTH ABOUT THE CONNECTION BETWEEN THE ARCH WIRE AND THE BRACKET.