Chin Correction: Review of Pediatric Clear Aligners Invisalign First

Hello,

Let me introduce pediatric clear aligners, Invisalign First, from Apgujeong.

This is a growth-oriented orthodontic treatment for children with skeletal Class II malocclusion, that is, chin retrusion correction.

When people visit an orthodontic clinic because of protruding upper teeth, the upper teeth may not actually be the problem.

Sometimes the lower jaw is small, making the gap between the upper and lower teeth large, so the upper teeth appear relatively protruded.

This child also came in for protrusion correction, but the cause was a small lower jaw, commonly called a retruded chin.

So we provided growth treatment for chin retrusion.

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The first thing that stands out is the gap between the front teeth, but this spacing is not a major issue because it can close as the canines erupt.

More importantly, the upper teeth cover the lower teeth too much, so the lower teeth are not very visible.

This is called deep overbite.

There is also a midline discrepancy, where the center lines of the upper and lower teeth do not match.

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From the side, the upper teeth look quite protruded.

But skeletal analysis shows that this is because the lower jaw is small.

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The palate is narrow and the front teeth are crooked.

After taking a hand growth plate X-ray, we found that the peak growth period still remained.

After explaining Invisalign First treatment, we started treatment with the goals of arch expansion, tooth alignment, improvement of deep overbite, and growth correction for chin retrusion.

In Invisalign First treatment for chin retrusion, there is a useful function called MA.

It functions like the jaw-orthopedic appliances used in the past, such as Activator, Frankel, and Bionator, which control jaw position and growth.

The principle is that wings appear on the Invisalign clear aligner, and when these parts interlock and bite together, they guide the jaw into the correct position.

Its effect is no less than that of conventional jaw-orthopedic appliances, and because it causes fewer tooth-related side effects such as lower front teeth flaring, it is often used for chin retrusion or asymmetry treatment.

Usually, arch expansion, front-tooth alignment, and improvement of deep overbite are completed first, and then the MA phase begins midway through treatment.

From April 2023 to September 2023, the patient wore appliances from stages 1 to 25 for six months and completed arch expansion, front-tooth alignment, and improvement of deep overbite.

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Matched upper and lower midlines and improved deep overbite

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The protruding front teeth also moved back into place.

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The previously narrow palate arch widened, and the front teeth became neatly aligned.

According to the ClinCheck treatment plan, this is the dentition expected at stage 25, and because the treatment progress was good, the actual intraoral condition is similar.

Now it is time to begin growth correction for the chin in earnest.

From stages 26 to 57, this is the MA phase that guides the position of the lower jaw, and if you look at the appliance, you can see the parts marked in blue called "wings" protruding in two pairs each on the upper and lower sides.

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This is how it is actually implemented inside the mouth.

If the lower jaw is not brought forward to bite, the mouth cannot close because the wings interfere with each other.

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From the front, it looks like this.

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This photo was taken six months into MA treatment.

During the MA treatment phase, the front teeth contact first and the molars are lifted off.

This is an unavoidable part of the process.

Later in MA treatment, if the molar portions of the appliance are cut and worn, the teeth will naturally contact again.

There is another reason for cutting and wearing the molar portions of the appliance later in MA treatment.

If chin retrusion treatment has been successful, the jaw position should remain the same even without the wing parts of the appliance.

This is also to check that.

If the wings are removed and worn, meaning the part that helps bring the jaw forward to bite is gone, and the jaw shifts backward again, then the MA phase needs to continue longer.

For this child as well, stages 53 to 57, which were the final appliances, were worn after cutting off the molar portions and leaving only the front-tooth portion.

After wearing all 57 appliances over a total of 15 months, including six months of orthodontic treatment and nine months of MA treatment, this was the result.

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For the final five appliances from stages 53 to 57, the molar portions were cut off to help stabilize the bite, and unlike the photo from last February, the molars now meet well.

In addition, even after wearing the cut wings for more than a month, the lower jaw did not shift backward again or lose the bite, confirming that the jaw position is very stable.

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Everything looked good, but we expected there might be a slight lack of space for the canine eruption site, so we decided to make one additional set of appliances.

From July 2024 to January 2025, after wearing the second set of appliances for seven months to secure a bit more space for the canines, treatment was completed.

Here are the post-treatment photos.

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The molar bite is good, and many of the remaining baby teeth have fallen out while permanent teeth are erupting.

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Enough space was created for the canine eruption sites.

A wire retainer was attached to the four front teeth, and a removable appliance for space maintenance was also inserted to prevent the canine eruption space from narrowing again.

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Retainers are important for adult orthodontic treatment, but for children, because the mouth changes rapidly as baby teeth and permanent teeth are mixed together, thorough retention is especially important.

I will post an update once this patient has all of the permanent teeth.

I expect the dentition to transition into the adult stage within about six months.

Now let’s compare before and after treatment.

The total treatment period was 22 months.

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Neatly aligned front teeth and enough space for permanent teeth

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The protrusion of the upper teeth has been greatly improved.

You may think the protruding upper teeth were moved backward, but in fact, the upper teeth did not move back; rather, the lower jaw bone that supports the lower teeth grew forward.

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Improved facial appearance

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The ANB value, which indicated skeletal chin retrusion before treatment, was 6.1, but it improved to 3.9, which is within the normal range, and the growth of the upper and lower jaws occurred favorably.

Invisalign First clear treatment can handle not only simple front-tooth alignment but also complex treatments involving skeletal issues.

If you are concerned about your child’s growth-oriented orthodontic treatment, please visit a nearby orthodontic clinic.