Tech Tip: FAQ about Engagers

We sent out a survey recently asking doctors for their questions about engagers.

In this week’s tip, we’ve consulted with our Chief Technology Officer, Dr. James Mah, to get answers to your questions.

DrMah.jpegDr. Mah comments on engagers

Engagers are an active area of research and development at ClearCorrect and elsewhere.

Many conceptual designs for engagers have been discussed in literature and professional forums, but when they are reduced to practice and the shape is thermoformed in the engager template, problems of adaptation and air gaps reduce the capability of many of these designs.

Without conclusive information and until the mentioned adaptation problems are resolved, ClearCorrect is happy to stick to simple horizontal and vertical engagers, which work well.

Engagers and the treatment setup

When we send you a treatment setup, we are presenting our best attempt to represent the course of treatment that you want to pursue for your patient—the recommendations shown are not absolute. It’s up to you to make any necessary changes to create a custom plan for treating each individual patient.

Engager preferences and timing can be discussed and adjusted according to what you want for your patient. Just let us know about your particular preferences when you submit your case or when approving the treatment setup.

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Engagers, templates & case revisions

On the treatment setup, if the engager is blue, it means it’s a new engager placement. If the engager is gray, it means it’s a previously placed engager.

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If you are submitting a case revision based on a prior step (not new impressions or scans), we’ll assume that the existing engagers are still on the teeth. You won’t receive a new engager template unless new engagers are needed.

General questions about engagers

Do you need engagers, or can the case be done without them? Are they necessary to use if prescribed?

Much depends on case by case variables such as tooth morphology and the type of tooth movement. To simplify these decisions, ClearCorrect has provided guidelines on which teeth and types of tooth movements that we would recommend engagers.

These guidelines are general and are for you only to use and apply to individual patients. Variables such as clinical crown height (shorter or longer), tooth morphology (shape), root morphology and positions need to be considered.

It is the doctor that prescribes the engagers. The technician only provides a recommendation. If engagers are recommended, there is a valid reason to use them.

That being said, it is possible to treat some patients without engagers. ClearCorrect has designed the aligners to be more retentive to often eliminate the need for engagers. In addition, overcorrection of specific tooth movements also helps to reduce the need for engagers.

If an engager is lost DURING treatment, should I use the tray currently in use as the engager template?

Yes, the current aligner will generally have the best fit. In addition, since it has been worn, the composite should easily release from the engager void.

Can you make the engagers bigger with a square or triangle shape to give more control?

ClearCorrect has ongoing research to continually improve engagers. The evidence does not support the need for larger engagers. Additionally, this would introduce other problems related to placement on smaller clinical crowns, occlusal interferences and esthetics.

What should I do if the teeth are very crowded? I find that it is difficult to adapt the engager template and place engagers when this is the case.

Treatment of severe malocclusion often requires expansion/IPR and some improvement of tooth positions to allow for ease of engager placement. Doctors can prescribe engagers for later in treatment when submitting the case or when approving the treatment setup.

Engagers wear down over time and end up needing to be replaced. Is there anything I can do to avoid this?

This can depend on the type of material being used for the engager. In general, a filled resin will be more wear resistant than one that is unfilled.

Is there a way for you to incorporate more than one engager on a tooth to aid in rotation or extrusion? At times, I think this would be helpful.

While this may seem to help with rotations, it causes other problems in removal of the aligners. Researchers have tested this hypothesis and found that the teeth became excessively loose and when the aligner was being removed and inserted – it produced excessive force on the teeth.

Questions about composite material or flash

What is the best material (both composite and bond) to use for engagers? Microfill? Flowable? Hybrid?

In general, a flowable composite is used, but much depends on doctor preference and wear factors. A patient with heavy occlusion will likely require a filled or hybrid material that is more resistant to wear.

What are the best methods to place them without overfilling? I’d like to know the precise way to place the composite into the template while avoiding an over or under abundance.

See our article on how to place engagers. Clinicians generally develop an eye for the appropriate amount of material to place in the engager void.

Some clinicians prefer to puncture the engager void on the labial side with an explorer to create a vent and allow release of excess material before light curing.

How do you deal with flash? Should I remove the excess composite that flows on the facial surface?

Excess flash is generally removed with a multi-fluted carbide burr. Yes, the excess should be removed as it may lift the aligner slightly and this may affect the fit and tracking of the aligner.

What do I do about having too much or too little flash or bubbles at enamel resin interface? Is there a way to get it just right?

These are both signs of problems with filling the engager void with too little or too much resin. See our article on how to place engagers for recommendation on how to install.

Questions about attaching engagers

I have difficulty with the engagers staying on the tooth when using the template. They tend to pop off, are a pain when attaching for the first time and not always successful. Do you have any suggestions?

There could be a variety of technical issues such as under/over etching, excessive primer, and inadequate material in the engager void. You can check for any of these issues and address accordingly.

How do you ensure that the position of the engager using the template matches the engager in the aligner?

The best way to do this is to make sure that the template is fully seated.

It can be difficult to remove the template especially when placing multiple engagers and when bonding each side of the arch separately. What should I do about this?

Application of Vaseline usually helps to release the engager from the template.

When attaching an engager to a decalcified tooth, the composite does not stay on the tooth. Do you have any suggestions?

This is a complication of bonding to decalcified surfaces. It will not be possible to bond to severe decalcification. Glass ionomer materials may help.

I have trouble attaching engagers when teeth are lingual. Is there a trick to doing this?

Treatment of severe malocclusion often requires expansion/IPR and some improvement of tooth positions before placing engagers, to allow for ease of placement. Doctors can prescribe engagers later in treatment, when submitting the case or when approving thetreatment setup. You want to stage the treatment setup to start correcting the teeth from their lingual positions and place engagers later.

Questions about removing engagers

What is the best/easiest way to remove engagers? I have completely drilled off and attempted to remove with hand instruments.

A multi-fluted carbide burr is generally best.

It’s hard to see when you have removed the majority of the engager. Do you have any suggestions for making sure the entire engager is removed?

This is the same problem in restorative dentistry when an existing composite restoration is removed. Use of a metal instrument will show which areas have composite resin remaining. Some clinicians use a common pencil to help identify resin fragments.

How do you ensure you don’t remove any enamel when removing buttons?

A bond/bracket removing plier is recommended.

Questions about engager shape and size

On two max canine, is it possible for one engager to be thicker than the other?

This is most likely caused by differing amounts of composite resin placed in the engager voids.

The shape is too rounded. What about engagers with sharper corners?

ClearCorrect has ongoing research to continually improve engagers.

Some of the designed engagers prevent removing aligners. Is it possible to have a different design or to apply them later?

Treatment of severe malocclusion often requires expansion/IPR and some improvement of tooth positions before placing engagers, to allow for ease of placement. Doctors can prescribe engagers later in treatment, when submitting the case or when approving the treatment setup.

Questions on engagers and tracking/fitting issues

Sometimes they don’t fit. The previous aligner will fit perfect but the next one, or new one, won’t. What should I do about this?

Review the last fitting aligner. There may be tracking issues that have gone unnoticed until the next aligner. If tracking issues are present, have the patient stay with their current aligner, or you can request a revision.

Sometimes the engagers do not line up properly with the aligner even immediately after placing them. It seems like a problem with the fit of the template. Would it be best to maybe place engagers first before trying to move any teeth at all, like before step 1?

There may have been tracking issues prior to placing the engagers. It is possible to have the patient wear the next aligner without the engagers and return at the next visit and use the aligner as the engager template instead of the provided template.

Could the shape of the engager be enhanced to encourage continued seating of an engager when teeth aren’t tracking (extruding)?

This would be difficult to do. Teeth are being moved in fractions of a millimeter or 1-2 degrees of rotation. Another approach could be the use of a thermoforming plier to place divots or pressure points (aka dimples) at specific sites of the aligner.

The teeth sometimes have trouble tracking and end up not engaging after a while and the case ends up needing a revision. This is frustrating. What can I do about this?

Refinements/revisions are common with clear aligner treatment. There are numerous scientific articles on the efficiency and accuracy of tooth movements with aligners. The need for revisions increases with the complexity of the malocclusion.

Sometimes rotated teeth don’t track in the engagers, why is this and what can I do?

Much depends on the tooth, root length and root morphology. Be careful not to advance too quickly through the aligners. If necessary, you can extend the patient’s wear schedule to get the needed movements.

I rarely have engager cases that track adequately. What could be the reason for this?

Engagers are usually recommended for more difficult movements, so it's not surprising that those movements may be more prone to tracking issues. Patient non-compliance or advancing through the aligners too rapidly can cause cases to go off-track. Use of Chewies can help to reduce tracking issues.

 

We hope you found this information helpful! There's lots more where this came from—check out our Help Center, which is filled with useful information for treating your patients with clear aligners.

Also, don't miss our advanced training series of webinars on various topics related to clear aligner treatment.

Until next time…

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