February 15, 2021

Whatever happened to Invisalign Mandibular Advancement?

In January 2019, I wrote a post about the potentially misleading claims on Invisalign Mandibular Advancement’s treatment effects. This was a new appliance that Invisalign claimed “moved the lower jaw forwards and simultaneously aligned the teeth.  I was assured that research data was “coming out soon”.  So I thought that I would carry out a quick search to see if I could find any more data.

Firstly, I had a look at the Invisalign Mandibular Advancement website.

On the first page they stated;

Invisalign clear aligners with mandibular advancement:

  • Straightens the teeth
  • Have precision wings that push the lower jaw forwards
  • Deliver results you will be smiling about

“With Invisalign clear aligners with mandibular advancement, you can straighten your teeth while the precision wings move the lower jaw forward, replacing bulky appliances.”

I also had a look at the Doctor’s section of the same website.  There were some Invisalign articles by KOLs showing case reports.  They mentioned “mandibular advancement” several times.  Now, to me, “mandibular advancement” means moving or growing the lower jaw forwards.  As a result, they are making claims that Invisalign Mandibular Advancement changes the skeletal pattern.

Following my initial post Invisalign responded and informed us that they were running a large cohort study.  They reported some of the results in their response blog post.  The data they presented showed minimal skeletal growth.

Two years later: iI there anything out there?

anybody

I did a quick literature search to find any report or journal article about the extensive study that Invisalign was doing.  I found very little.

One report I found was from the AAO meeting in 2019 where Dr Barry Glaser did a presentation. (Dr Glaser is a paid KOL for Invisalign). His presentation can be found here.

I have extracted some data from it.

They looked at 40 patients aged 13.2 years who were treated by 10 different providers.  The mean duration of phase 1 treatment was 13 months.  I looked at the data for overjet and ANB.

Initial Final Change
Overjet (mm) 5.1 3.3 1.8
ANB (degrees) 5.99 4.64 -1.35

 

The only other information I found was a Master’s Thesis by Dr Blackham from UBC.  In this project, he retrospectively looked at 19 patients treated by Twin Blocks and 13 treated by Invisalign Mandibular Advancement.  This is the data that I extracted for overjet.

Appliance Overjet Change ANB Change
Twin Block 3.57 -1.16
Invisalign MA 1.16 -1.11

 

When I looked at this data. My feeling is that there is nothing much to get excited about. The cases appear to be mild, and the amount of tooth movement and skeletal change is low.  In fact, when you look at the Invisalign data, they seemed to take a long time to not get very far? I would be expecting to faster overjet correction with any other functional appliance.

What did I think?

Firstly, I cannot help feeling disappointed that there is no additional information from Invisalign two years after my posts.  Indeed, this is even more frustrating that the company and the KOLs are still making their claims with very little evidence. Even from their own study.

When we look at the data from the two sources that I found. It is relatively similar.  We can conclude that minor overjets are reduced, and there is some skeletal growth. However, this is what we would typically expect from average growth.  Furthermore, the amount of “growth” is no different from other functional appliances.  Which is nothing much!

In his presentation, Dr Glaser stated that “the correction with Invisalign Mandibular Advancement was similar to other forms of Class II correction”.  If we consider that other forms of Class II correction do not change the position of the mandible. Then we cannot call the new Invisalign appliance a “mandibular advancement” appliance.

Conclusions

I will conclude with the same statement that I made in my blog two years ago.

“No, we do not believe your claims”.

This time I will also add

“Invisalign KOLs why are you making these claims”?

Perhaps one of the usual suspects could answer?

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Have your say!

  1. Avatar

    So basically, no more value than using rubber bands with invisalign, except for may be slightly less compliance needed.

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    I think we need to properly admit to ourselves that we can’t grow mandibles (or probably maxillae). It’s not only invisalign who say they can, it still seems like most of the profession. Armed with this revelation maybe we can be more realistic in our aims and avoid unnecessary and time wasting treatment. Or maybe we are too wedded to our functionals.

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    Great work Kevin O Brien,
    The only thing I can’t figure out from your quotes is if your favorite album is The Dark side of the moon or The Wall … !
    Best regards
    Daniele

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    Totally agree with misleading terminology “mandibular advancement”.

    Giving the similar concept of both appliances, I think it is reasonable to have similar effect and changes magnitude.

    But does it really worth the cost, time (shipment worldwide) and treatment duration in treating Cl II for adolescent patients!!
    Maybe if there is an additional feature or helpful advantages it will support its use, consequently the studies and publications.

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    It’s now called ‘jumping the bite’.
    As mentioned repeatedly during the AAO Winter Conference this past weekend.

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      This term was used when I was in school 35 years ago. I am fairly certain that it’s origin goes much farther back.

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        Robert,
        You are correct. Bite jumping appliances (BJA) have been around for decades. And the phase ‘jumping the bite’ has been used to describe Class II correction using many appliances. So, it’s no surprise that the phrase would be used to explain the ‘mandibular advancement’ effect of clear aligner treatment.

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    The reliance on ANB change from cephalometric analysis might be misleading since the untenable assumption is being made that there are no changes in the size, shape or position of the midface, which is unlikely. Similarly, size, shape or positional changes of the mandible cannot be reliably gauged from cephalometry; the perceived net changes are likely a combination, producing a new spatial matrix.

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    I am a pretty experienced Invisalign user and after careful discussions with parents and subjects I decided to try 5 consecutive ‘mandibular advancement appliances’.
    This was not one of my better decisions. Every one failed due to the same reason, which is essentially the material isn’t up to what’s being asked of it. The lower aligners especially are too flexible to take the position of the wings, consequently the wings roll out when patients occlude so the appliance looses its sagittal activation. If I had looked more closely at the design before deciding to try them I could have spotted it.
    Invisalign will tell you to add lingual attachments to increase the retention, but they do not create sufficient retention to overcome the lack of rigidity. Again this isn’t surprising on young teeth with short clinical crowns.
    I explained this to them on their stand at the conference in Glasgow, but was met with a rather pitying look.
    Don’t waste you and your patients time and money.

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    Kevin, I find it astonishing that some orthodontists still believe in the 21st century that they can grow mandibles. I thought this was put to rest several decades ago. Cl II corrections, regardless of the mechanism used, results in dentoalveolar corrections. Occasionally, I have seen some bending of the mandible, but that is not growth.

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    I entirely agree with you Larry, though I feel the question here is does the appliance match or improve the results which you can expect from the current iterations of functional appliances. The gold standard for me is the twin block, though I accept that other functional appliances are available!
    My experience is that the Invisalign mandibular advancement appliance does not, so consequently, mudding the waters with cephalometrics is irrelevant Prof Singh.

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    A full cusp class II is 6 mm, and thus. it would take 3 years of pubertal growth spurt to get there. It’s difficult enough to get patients to wear the appliances for 12 months. Research has shown that fixed functional appliances have little effect on mandibular growth.
    Jeffrey Cooper DDS, MsD
    Diplomate American Board of Orthodontics
    Assistant Clinical Professor
    Graduate Orthodontic Department
    Rutgers School of Dental Medicine

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    The idea that orthodontists can’t grow mandibles is entirely based on cephalometric studies. You can’t have it both ways guys –

  12. Avatar

    Perhaps I am considered a “usual suspect”?
    Not sure thought that I can add much value to the discussion as my personal philosophy on functional appliances is in tune with Dr White so experience with MAF is limited. I was of the understanding that it was being re-designed and I am not sure if this has as yet occurred. I have never presented on that topic. From Day 1 Align Technology has marketed appliances prior to conclusion of external clinical studies, bowing to the pressure of the IPO. The first publication, a progress report on the UOP Feasibility study (case reports) was not published until 2000, Invisalign released prior to that date. I don’t foresee this pattern changing for any orthodontic “innovation” produced within a corporate structure, particularly considering the increasingly competitive market and the ubiquitous conflicting relationship between marketing and clinical entities within corporations.
    As a specialty, residents are generally well prepared and “immunized” against marketing claims and are educated to apply techniques and products judiciously. That’s why we study biostatistics and conduct endless article reviews. I am yet to see truly rigorous literature (PRCCT with large enough sample size to be valid) concerning efficacy of aligners, and very little, if any, exists for fixed appliances. (if you have just fallen off your seat, please provide the study protocol for efficacy of brackets and wires and we may use that same protocol with aligners, outcome studies conducted by greats Shaw and Richmond and O’Brien were not complimentary).

    I fear those with less immunity to marketing claims are not as well prepared, the dental profession at large. I am not convinced that we can ever experience the utopia where we may withhold product release from every dental (or other) corporate manufacturer until a high level of external evidence is determined; higher than that of the TGA equiv. or other medico-legal requirement; however we may continue to educate ourselves to identify and call out marketing spin, – as long as we do it equally for all companies and their new products. You will be very busy Kevin!

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