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Headway Medical Dental Bracket Case
Aug 11, 2018

Introduction to treatment:

It is not the intent of the author to set forth a procedure manual on edgewise orthodontic treatment. The intent is to suggest procedures utilizing an interactive archwire slot that will augment the pre-adjusted edgewise slot during treatment of particular problems. It is assumed that the practitioner will be well versed in edgewise mechanics utilizing the pre-adjusted bracket system.

The interactive slot is unique in that the archwire is held into the interactive slot utilizing the same elements(steel ligature tie,  o rings and power chain ) employed when securing an archwire in the pre-adjusted edgewise slot.

The following is a discussion on when, where and how the interactive slot can be utilized to make orthodontic treatment faster and simpler.

Treatment

The objective of the Ultra bracket system is to add to the pre-adjusted edgewise bracket an interactive slot witch will make existing concepts of treatment easier and enable new concepts of treatment not possible with the pre-adjusted edgewise slot alone. With the addition of the interactive slot the following can be accomplished;

1. Leveling of the arch and alignment of tipped teeth is accomplished without exerting adverse forces on the adjacent teeth and or bite closure.

2. The interactive slot opens toward the given. Rotational corrections are corrected much faster because the rotational force of the archwire is generate by non-yielding metal to metal contact between the archwire and the bracket. Insertion of the archiwre into the interactive slot is easy and once inserted, unlike the edgewise slot, it tends to stay in place making ligation of the archwire easy.

3. Bite opening can be accomplished more efficiently by utilizing the interactive slot. The narrow mesial distal dimension (0.050) and the wide vertical dimension (0.035) of the interactive slot allow effective intrusive force to be placed on the six anterior teeth.

4. Bodily en masse retraction of the anterior teeth in extraction cases without external anchorage and or complicated archwire configurations can be easily accomplished.

5. Differential resistance between the maxillary arch and the mandibular arch or within the same arch can be established by utilizing the pre-adjusted edgewise slot in the arch or teeth needed for anchorage and the interactive slot in the arch or teeth where retraction or protraction is needed.

6. Dental compensation needed to establish maximum interdiction of the teeth in apical base class-ii and III discrepancy cases can be easily accomplished.

Mechanics of bite opening

Reverse curve archwires are commonly used in bite opening procedures. However, their effectiveness is degraded by the narrow vertical dimension and wide mesial distal dimension of the edgewise slot. Their effectiveness is further degraded if the cuspids are distally tipped. The wider and the more vertically narrow the edgewise slot, the more of the action of the archwire is exerted on the bracket itself , instead of the teeth. The only portion of the archwire that works on the teeth is the arch-length between the brackets. The length of the archwire engaged in the edgewise slot acts on the slot, not the teeth.

Illustration 1: bite opening

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0.016 reverse curve archwire in 0.018 pre-adjusted slots

The reverse curve 0.016 Niti archwire exerts little or no intrusive force on the incisors or cuspids when placed in the pre-adjusted edgewise slots. The narrow vertical opening of the edgewise slot in conjunction with the wide mesial distal dimension flattens out the archwire. The slight distal tip of the cuspids further flattens out the anterior bow of the reverse curve archwire. Note: the archwire is not touching the brackets on the Centrals and laterals.

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0.016 reverse curve archwire in 0.035 interactive slots

The reverse curve 0.016 nickel titanium archwire placed in the interactive slot clearly exerts an intrusive force on the incisors and the cuspids. The interactive slot is narrow mesial or distal. (0.055) and the vertical opening is 0.035. the distally tipped cuspids has no effect on the archire.

Illustration 2: when a greater magnitude of force is needed.

A. 0.016 steel archwire is used in the interactive slot with bi-lateral gable bends in the archwire between the cuspids, as near to the bicuspids as possible. This archwire will produce an extrusive force on the posterior teeth and an intrusive force on the six anterior teeth. No rotating force on canines. Bite opening and cuspid class II correction is accomplished much faster. The same archwire configuration can be used in the mandibular arch. A. 0.016 or 0.018 steel archwire can be used depending upon the forces required to open the bite.

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Illustration 3: bite opening with the interactive slot.

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Maxillary arch: 0.016 steel archwire inserted into interactive slots with bi-lateral gable bends between bicuspids and cuspids, initial archwire placement.

Mandibular arch: flat 0.014 nickel titanium arhcwire in edgewise slot.

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Bite opening: correcting anterior rotations

In those cases where there is minimal horizontal overbite with significant vertical overbite, bite opening should be accomplished first before proceeding with rotational corrections in the mandibular anterior teeth. Both the maxillary and mandibular anterior teeth are thicker in the labial-lingual dimension at the gingival junction than they are at the incisal edge. Many times just opening the bite gives the necessary space to align the mandibular anterior teeth.

Illustration 4: bite opening and rotation corrections

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A. Closed bite with no anterior-posterior space to properly align mandibular anterior teeth.

B. Opening bite generates anterior-posterior space between the facial surface of the mandibular incisors and the lingual surface of the maxillary incisors.

Arch leveling: as relates to torque

The bite should be leveled to the point whereby a straight archwire will pass through the edgewise slot of the bicuspids , cuspids, laterals and centrals in both arches without being deflected in an occlusal direction. If a 18*25 archwire must be deflected toward the incisal to engage into the brackets on the central and laterals, the full base inclination builtinto the central and lateral brackets by the manufacturer will not be realized.

Illustration 5: arch leveling and torque

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There is 10 degrees of roque not realized due to the arch not being level. Lines C and D are parallel. If the archwire is deflected toward the gingival, the toque angle would be increased in proportion to the degree the arch wire is deflected.

The flexible nickel titanium arch wire is a good addition to the types of arch wires available to the practitioner when correction rotated or maligned teeth. However, due to its flexibility the nickel titanium arch wire is not the archwire of choice for arch leveling. The use of a steel arch wire in the interactive slot with gable bends between the cuspids and bicuspids , in conjunction with a nickel titanium arch wire in the pre-adjusted slot can be used to leveling the arch.

Rotational corrections

The advent of the new more flexibile arhcwires has open ip new possibilites in the mechanics of rotating teeth. The more flexible ones have made it easier to engage the arch wire into the edgewise slot. However, the major problem associated with correcting rotated teeth with the edgewise slot has not changed. The major problem has not been the engagement of the archwire into the bottom of the edgewise slot of the bracket on the rotated tooth, but rather keeping it there. Steel ligatures are very open used to hold the wire in the edgewise slot ,but more often than not the pressure against the tie by the archwire results in the tie stretching so that the archwire does not stay at the bottom of the edgewise slot. Elastomeric o rings are no usually strong enough to hold the archiwre in the bottom of the edgewise slot. Too often, the bracket on the rotated tooth is dislodged in the effort to set up a force system to align the rotated tooth.

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The headway ultra bracket system establishing a force system to align a rotated tooth by inserting a flexible, small gauge archwire in the interactive slot of the brackets and buccal tubes. This is process is much easier than employing steel ties, rotating wedges or springs. With metal to metal contact between the archwire and the bracket there is no possibility of the rotating force dissipating due to the stretching of the steel tie or the o rings. Power chain was added to speed up rotation.

Differential resistance

It is generally accepted that it requires considerable more force to move a tooth in a bodily fashion, than it does to tip a tooth. The greater force required for bodily movement will present a greater drain on the anchorage system. The greater force needed is due in part to the friction of the bracket against the archwire. Since the headway ultra bracket system has both a pre-adjusted edgewise slot for bodily movement and a interactive slot for tipping, differential resistance can be set up by simply selecting the edgewise slot for the anchorage teeth and selecting the interactive slot for the teeth to be moved. Differential resistance being defined as two separate units being acted upon by the same force and the result being that one unit is the primary movement unit. This can be accomplished either intro-arch or inter-arch. An example of intro-arch differential resistance would be in an extraction case where the anterior teeth need to be retracted posterity. The archwire is engaged into the edgewise slot in the posterior teeth an into the interactive slot in the anterior teeth. An example of inter-arch differential resistance would be in a case where the maxillary teeth need to be distalized but with little or no anterior movement of the teeth is desired in the mandibular arch. The mandibular teeth would have the archwire engage into the edgewise slot and the maxillary arch would have the archwire engaged into the interactive slot. Still another example would be a case where the maxillary posterior teeth need to be moved forward.

 

Non-extraction treatment

These are usually very simple cases to treat. The important thing is to determine why the cuspids are in a class II relationship. The mandibular anterior teeth could be in retro-version or the maxillary anterior teeth could be flared, or a combination of both.

Illustration 7: combination of flared maxillary anterior teeth and retro-version of the mandibular anterior teeth.

Molar class I, cuspids class II

Apical base class I (wits=-2mm to +3mm)

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The initial arch wires are 0.016 nickel titanium inserted into the interactive slots to correct rotations and align in the facial or lingual plane. The second set of archwires were 0.016 steel inserted into the pre-adjusted edgewise slots in the maxillary arch and in the interactive slots in the mandibular arch. The 0.016 steel archwire in the mandibular arch has bi-lateral gable bends between the cuspids and bicuspids to open the bite bu intruding the mandibular incisors. Class II elastics were employed at this tage of treatment. The third set of arch wire were 18*25 niti inserted into the pre-adjusted slots in both arches to finish the case. Light class II elastics were continued.