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David Gates DDS

'Ask the Expert’ Webinar

August 22, 2014

The Problem of Posterior Open Bites

Cosmetic, Reconstructive, and Implant Practice, Las Vegas

First GP Certified in Nevada - 2001

Taught 275+ CE 1s and 2s and Study Clubs

Awarded Top Speaker at Summit 2005, 2006, 2007. (Screwed up in 2008??)

Loves Invisalign

Has made most of the really good Invisalign errors.

Dr. David Gates

The statements, views and opinions expressed in

this program and related course materials are those of the

speaker.

Align Technology, Inc. may not endorse such statements, views or opinions.

Attendees are responsible for legal and regulatory compliance of any marketing and referral programs.

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Has your case ever finished with a posterior open bite?

It’s never happened to you???

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It happened to her!!

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It happened to him!

And it’s happened to me!!

Have you checked your

occlusion with Mylar shimstock?

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• What causes posterior open bites?

• What the consequences? Can’t we just leave it?

• Won’t it just stabilize on it’s own?

To solve this problem, we must know its causeand it’s consequences. (We must diagnose correctly.)

• Some say it come from intrusion of the molars?

• Some say you should cut off the ends of the aligners and let the teeth super-erupt. Is this so?

What is the cause of Posterior Open

Bites?

• Instability of Anterior Teeth.–Perpetual looseness or migration,–Fremitus, light or open anterior contacts–Possible super-eruption of posterior teeth.

What are the Consequences of

Posterior Open Bite?

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• Where is the force to accomplish this coming from?

• Interocclusal forces? Forces much greater than regular chewing forces which normally do NOT intrude natural teeth?

• Do the aligners show evidence of these forces? Does it happen at night?

• Could all 8 molars intrude with forces so gentle the patient is unaware of them?

• Does the patient wake up fatigued?

What forces would Unintentional Molar Intrusion require?

Is it an old Wives'

Tale??

Where did the idea of molar intrusion as the cause come from ?

And if it isn’t

molar intrusion, what is it?

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There are 5 reasons why you end up with Posterior Open Bites. *

* What you’re actually seeing is

Premature Anterior Contact

Since there is usually more crowding on the bottom than the top, the bottom requires more Proclination than the top – Overjet is eroded.

5 Causes of Premature Anterior Contact

Early Thinking & Planning

More crowding

Less Crowing

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1. More Proclination on the bottom than the top – Overjet is eroded

Failure to Intrude – Overbite is reduced.

5 Causes of Premature Anterior Contact

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Failure of 4 or 6 anterior teeth to complete their intrusion is difficult to

spot.

Failure to intrude a single tooth is easy to

spot.

5 Causes of Premature Anterior Contact (PAC)

1. More Proclination on the bottom than the top – Overjet is eroded

2. Failure to Intrude – Overbite is reduced.

Collapsing of the Arch - Overjet is eroded

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5 Causes of Premature Anterior Contact (PAC)

1. More Proclination on the bottom than the top – Overjet is eroded

2. Failure to Intrude – Overbite is reduced.

3. Collapsing of the Arch - Overjet is eroded

Tooth Size Discrepancy – Space around small laterals is closed. Overjet is eroded

Tooth Size Discrepancy - Overjet is eroded

1. This means that the laterals are too small for the arch, and have space around them, and you request that they close the spaces.

2. This makes the arch too small for the lower teeth.

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Smaller Laterals Correct sized laterals

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Smaller Laterals

Correct sized LateralsSmaller Laterals Correct sized laterals

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5 Causes of Premature Anterior Contact

1. More Proclination on the bottom than the top – Overjet is eroded

2. Failure to Intrude – Overbite is reduced.

3. Collapsing of the Arch - Overjet is eroded

4. Tooth Size Discrepancy - Overjet is eroded

You approved a very tight overjet set-up. No room for error.

– Can you fix an open bite during Treatment? –

– Can you fix it by cutting the aligners and letting the teeth super-erupt?

During Treatment

Before you cut the aligners, ask yourself 4 questions about Super-Eruption.

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1. How big is the open bite? (How far open is it?)

2. Where is the Premature Anterior Contact, and on how many teeth?

3. When you see a super-eupted tooth in a patient, does the gingiva follow the tooth, or does the tooth get longer?

4. Would you want your own teeth super-erupted if they had not intruded??

• If it’s a tiny open bite, cutting the aligners might just work.

• If the contacts are on the cupsids or bicuspids, it also might just work. If it’s on the centrals or laterals, it probably won’t.

• Do you know how to correctly equilibrate an occlusion. If it’s slight, this is preferable.

How to fix it

once it’s open.

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• You must make sure the ClincheckMATCHES what’s in the mouth.

• You must have an OPEN BITE CLINCHECK. Otherwise, your clincheck means nothing.

The computer automatically closes the bite, by default.

You’re in charge! Take control.

Won’t this happen automatically?

Here are the 5 Steps to get back on track.

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1. Measure the open space interocclusally.

1. Measure the space interocclusally

Take perfect impressions, or a perfect scan. (Create as little need for editing as possible.)

1. Measure the space interocclusally

2. Take perfect impressions, or a perfect scan. (Create as little need for editing as possible.)

Communicate the Interocclusal space, and ask for a perfect mounting of the case. (With an open bite.)

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1. Measure the space interocclusally

2. Take perfect impressions, or a perfect scan. (Create as little need for editing as possible.)

3. Communicate the Interocclusal space, and ask for a perfect mounting of the case.

Review the Clincheck, and note discrepancies between the mouth and the Clincheck.

1. Measure the space interocclusally

2. Take perfect impressions, or a perfect scan. (Create as little need for editing as possible.)

3. Communicate the Interocclusal space, and ask for a perfect mounting of the case.

4. Review the Clincheck, and note discrepancies between the mouth and the Clincheck.

If it doesn’t match exactly, call Align and speak to one of the Orthodontic Supervisors at Align. They are anxious to help.

Once you’re SURE the Clincheck matches the real bite:

• Make sure that the clincheck does not include super-euption of the molars.

• Plan the Clincheck to avoid any of the 5 reasons you got PAC in the first place.

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A. Procline the uppers

B. Retrocline the lowers

C. Intrude the uppers

D. Intrude the lowers

Ask for any combination of 4 movements

Which movements are more difficult??

A. Procline maxillary teeth

B. Retrocline mandibular teeth

C. Intrude Maxillary teeth

D. Intrude Mandibular teeth

• Patient wears the aligners as usual until the posterior teeth drop into occlusion.

• Once the front teeth are out of the way, they’ll be back into occlusion.

1. When the aligners arrive….

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A. Less upper lingualization

B. Leaving more spaces and use restorations

C. More IPR on the lower

D. More intrusion on upper and lower.

2. Discard the remaining aligners, and begin a new Clincheck

• Avoiding the 5 causes of P.A.C.

• Use over-correction tools

• Understand the ‘CREST’

How to avoid Open Bites in the future

1. More Proclination on the bottom than the top – Overjet is eroded

2. Failure to Intrude – Overbite is reduced.

3. Collapsing of the Arch - Overjet is eroded

4. Tooth Size Discrepancy - Overjet is eroded

5. You approved a very tight overjet set-up. No room for error.

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[oh‐ver‐kuh‐rek‐shuh n] IPA Syllables

Word Origin

Noun

1.  Correction beyond what is needed or customary, especially when leading to error; overadjustment:

• C-chain Overcorrection

• Single Tooth Overcorrection

• Multiple tooth Overcorrection

1. C-chain Overcorrection

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I recommend these at the end of every case, (including those with no IPR.)

1. C-chain Overcorrection

2. Single Tooth Overcorrection

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• C-chain Overcorrection

• Single Tooth Overcorrection

• Multiple teeth overcorrection

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Ask for

morethan you need.

• Avoiding the 5 causes of P.A.C.

• Use over-correction tools

• Understand the ‘CREST’

How to avoid Open Bites in the future

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Things to watch out for:

• Don’t collapse the arch

• Build in a little extra overjet to the case (I build in 1mm most of the time.)

• Ask for a little more intrusion than you need. (Overcorrect intrusion)

• Watch the intrusion carefully.

• Don’t get trapped into skipping restorative when it’s needed.

• Don’t make it so complicated.

• Figure out what the mouths wants and give it to them.

• Make your clinchecks as simple and predictable as possible.

• Here’s an example:

Final Message:

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• He wanted to straighten her teeth.

• He wanted to get the midline correct.

What were his objectives?

A Gap AFTER

Midline off BEFORE Midline off AFTER

A Gap BEFORE

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• Ask yourself: “What does the mouth want?”

• If it could have it’s own way, what would it do?

• How can I give it what it wants?• Which arch has the problem?• Am I punishing one arch for the

errors of the other??

There is an easier way!

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The HARD way The EASY way

Here’s what he suggested instead.• I could extract the tooth on her right. • I asked what that would do to the overjet. • He said it would decrease it. That’s right!!• I said he would have posterior open bite.• He suggested he extract the two bicuspids on the

bottom.• I couldn’t hardly believe what I was hearing.

(“Let’s extract 3 of my daughter’s teeth to correct a 3mm midline error!”)

I could extract #5 and then both sides 

would match! 

I could extract #5 and then both sides 

would match! 

What would that do to the overjet??

What would that do to the overjet??

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It would probably decrease the 

overjet.  

It would probably decrease the 

overjet.  

Correct.  And what might that produce?  

Correct.  And what might that produce?  

Maybe a posterior open bite.  

Maybe a posterior open bite.  

Yes.  That’s one way it happens.  

Yes.  That’s one way it happens.  

Then maybe I could also extract the two bicuspids on the 

bottom.  

Then maybe I could also extract the two bicuspids on the 

bottom.  

Really?  Are you serious?  You’d extract three teeth 

on your daughter to correct a 3 mm midline 

discrepancy?

Really?  Are you serious?  You’d extract three teeth 

on your daughter to correct a 3 mm midline 

discrepancy?

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• Don’t make it so complicated.

• Figure out what the mouths wants and give it to them.

• Make your clinchecks as simple and predictable as possible.

Final Message:

Questions?

To obtain your CE certificate for this program please complete a brief survey at:

Upon completion of your survey* you will have immediate access to your CE certificate.

*This survey is only available to the participants who attend the “live” presentation via the webinar/phone. Participants who complete the archived program on the Education Tab of the Invisalign Doctor Site need to complete a CE test to obtain their CE certificate.

http://learn.invisalign.com/asksurvey

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Has your case ever finished with a with posterior open bite?