Aisling Byrne considers the use of auxiliaries as an adjunct during aligner therapy.
Aligner treatment as a means of correcting a malocclusion has become increasingly popular over the past five years. Indeed, many of my patients now request aligners are used to straighten their teeth, rather than traditional braces.
As a result, I now treat many complex malocclusions with aligner therapy. Often, this is only successful with careful planning and incorporation of auxiliary components as required, as aligners alone are often insufficient to complete all aspects of the treatment.
Most of these auxiliaries are in the form of buttons, elastics and power chain, but also include the occasional use of sectional fixed appliances in the most difficult of cases. It is important to identify such cases where auxiliaries are likely and forewarn the patient of this necessity.
This article will explore the main reasons I use aligner auxiliaries, including:
- Diastema closure
- Derotation of severely rotated teeth.
Aligners are less predictable with extrusive movements and there is an increased incidence of loss of tracking, especially on smaller teeth with reduced surface area (such as upper lateral incisors).
In this situation, the IX891 Ixion hole punch can be used to relieve an area in the aligner, and a sling elastic can then be attached from the buccal of the tooth to the palatal of the aligner to apply an extrusive force.
This is great for extruding those stubborn lateral incisors (Figure 1). Figure 1 shows loss of tracking on the upper right lateral incisor. The tooth has failed to extrude as planned with the aligner treatment.
This can occur for a number of reasons, including excessive extrusion, poor patient compliance with aligner wear and a small tooth (with reduced surface area). This commonly occurs on lateral incisors, as they are relatively small teeth with reduced surface area.
A button (in the aesthetic zone, I tend to use ceramic from DB Orthodontics) has been placed gingivally on the tooth and IX891 Ixion pliers have been used to remove a semi-circular area beneath the button (with adequate clearance) to provide space between the aligner and the button to allow it to extrude.
An intraoral elastic is hooked over the button around two slits made in the palatal surface of the aligner behind the UR2.
FIGURE 1: Extrusion with buttons and elastics
Another reason I use aligner auxiliaries are for the final closure of very small (<1mm), stubborn spaces (particularly upper midline diastemas). I punch out two holes in the teeth adjacent to the space using the Ixion hole punch pliers. Next, I bond two buttons and place power chain (see red arrow on Figure 2b) for four weeks. Total space closure should occur in this time frame. Again, I usually use ceramic buttons in the upper anterior region where they are visible. Figures 2a and 2b show space before closure and when fully closed.
FIGURE 2A : Diastema closure – before. Aligner auxiliaries can be used to close small, stubborn spaces. FIGURE 2B : Two buttons bonded and power chain placed for four weeks
FIGURES 3A, 3B and 3C: Derotation of severely rotated teeth
FIGURE 4A: Power arm, area in composite. FIGURE 4B: Power arms in situ
FIGURE 4C: Space closure after power arms
Derotation of severely rotated teeth
Aligners can need some help when aligning severely rotated teeth. I will often use buttons on severely rotated teeth, as shown in Figures 3a to 3c. Two holes are punched out (using the IX891 Ixion pliers), one on each rotated tooth, either palatal or buccal, depending on the location of the force required.
DB Orthodontics power chain is then placed between the two buttons to provide an additional force to help derotation, and avoid loss of tracking occurring (Figures 3a and 3b).
Depending on the direction of additional force required, buttons may need to be attached either buccally or palatally. Occasionally, buttons can be attached to both buccal and palatal tooth surfaces of the same tooth. For example, in the case highlighted in Figure 3, a button could also have been attached from the most distal aspect of the UR4 and the UR2. However, punching too many holes in the aligners may weaken them and increase the risk of fracture.
Metal buttons are ideal when outside the aesthetic zone, as they are smaller and therefore less likely to cause irritation and discomfort. In addition, they are significantly cheaper. I find many patients are quite happy to have metal buttons, even at the front of their mouth, so it is always worth asking them which they prefer.
This technique is highly effective and helps prevent loss of tracking and slower tooth movement that would otherwise occur. Remember, for the most effective results, always site the buttons as close to the centre of the mid-axis of the tooth as possible (Figure 3c).
Either attach power chain between the buttons, or ask the patient to place a class I elastic on and change every day (this, however, relies heavily on good patient compliance).
Power arms, also from DB Orthodontics, can be bent in 018 stainless steel using Ixion light wire pliers. They are great to ensure bodily movement and help prevent tipping of teeth. I use these in extraction cases, especially when I want to retract a canine that is either upright or distally tipped.
A force (either a class I elastic or power chain) is applied between the hooks, across the extraction site. These hooks allow the force to be closer to the centre of rotation of the tooth, thereby encouraging a bodily movement, rather than a tipping one. If power arms are not used in these cases, the premolar and canine are more likely to tip into the extraction space, giving a poor end of treatment result.
FIGURES 5A & 5B: Class II and III elastics
FIGURE 5C: Class III elastics
FIGURE 6A: Open bite case treated with vertical settling elastics and aligners
FIGURE 6B: Vertical settling elastics
FIGURE 6C: Vertical settling elastics
FIGURE 6D: After vertical settling elastics
Figures 4b and 4c show how a power arm can be bent up and how mechanical retention can be obtained for the section in composite.
Class II or III elastics
Class II or III elastics are used to increase/ reduce overjet or for anchorage support during alignment or space closure. Often, I will see a patient for a review mid-treatment and decide they need to start elastic wear from canine to molar, in either a class II or III direction.
In these situations, I place hooks on the canines with the IX890 Ixion tear drop plier and DB Orthodontics buttons on the first molars (using the Ixion hole punch pliers to relieve the aligner in the region of the button). Patients often find it difficult to place an elastic on a molar hook but manage well on a canine.
Remember, avoid placing a hook on a tooth without an attachment, as the force will likely cause a displacement of the aligner, and/or loss of tracking. In such cases, it is preferable to place a button on that tooth (Figure 5a). If power arms are already present, these can also be used to attach class II and III elastic on to (Figures 5b and 5c).
Vertical settling elastics
During aligner treatment, there is a tendency to develop lateral or posterior open bites. These can be easily and quickly settled using either buttons or brackets together with vertical settling elastics.
The case highlighted in Figures 6a to 6d is an example of this. The initial situation is shown in Figure 6a. Figure 6b shows the patient wearing vertical class I elastics attached to lower incisor Evolve brackets, which are bonded to the upper and lower first molars.
The aligners are cut mesially to the open bites and are worn at night only (to hold anterior teeth in place). Vertical elastics are worn full-time. This patient also wore elastics on the left in a box shape, bonded to upper and lower fives and sixes. Patients should be reviewed at three to four weekly intervals, as the teeth can move very quickly with free settling.
This technique works really well and is much more efficient than trying to close open bites with aligners alone.
The use of auxiliaries as an adjunct during aligner therapy cases is considered an essential part of treatment for orthodontist aligner providers. They assist in achieving desired outcomes for the patient, in addition to providing a quicker, more predictable protocol.
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About Aisling Byrne
BDS (HONS) MFDS RCS MORTHO RCS M PHILORTH FDS ORTH RCS.
Aisling graduated from Bristol Dental School in 2000. She joined the orthodontic specialist registrar training programme at Birmingham Dental Hospital. During this time, she undertook a master’s in philosophy research. In 2007 she gained her Membership in Orthodontics from the Royal College of Surgeons. She was awarded her Intercollegiate Speciality Fellowship of the Royal College of Surgeons to gain consultant status. Aisling is an orthodontic specialist and currently works as a consultant orthodontist at a local hospital.
About DB Orthodontics
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