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Ortho lecture #2النمري. كاظم د

Last time we talked about interceptive orthodontics and its scope which is divided into three divisions:

1-local factors (lecture #1).2-displacement (anterior and lateral).

3-spacing and crowding.

Our topic today is CROWDING (it’s a crowded lecture also ) ……what is crowding (not crowdening….dr said that he does not want

any one in the clinics to say crowdening…), how to intercept crowding…

ENJOY ………

Crowding means that there is a discrepancy between the sum of mesio distal width of teeth present and the mesio distal width of the arch (arch parameter), i.e. there is no space enough in the arch to accommodate teeth, so they will not be well aligned, and will be crowded.

How to relieve crowding?

In order to relieve crowding we can do : 1-enlarge the arch or 2-reduce the mesio distal width of teeth and this can be done by either A-making teeth smaller by reducing their proximal surfaces (inter proximal stripping:: to cut from the mesial or the distal or both surfaces of each tooth).

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B-reduce # of teeth by extraction…

By the way we follow the above treatment in a fully developed dentition….but today we will talk about interception in a developing dentition (mixed) and we can say from what we have that the patient will

have crowding later on…

Q: Can we prevent crowding from happening?? Or reduce the severity of crowding before the completion of

development of the permanent dentition???

A: yes we can relieve crowding in a still developing dentiotion and this is known as interceptive orthodontics..

Q: how can we intercept crowding??

We have seven ways but we are not gonna talk about them all and they are (* = dr talked about it) :

1-space management* 2-molar distalisation

We here enlarge the arches by moving the molars more distally (we wont talk about it)..

3-serial extraction* 4-premolar extraction

5-first molar extraction* 6-lower incisor extraction

7-2nd molar extraction.

So as you can see the solutions are either space management or distalisation or 5 ways of extraction…

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SPACE MANAGEMENT..

What is space management??Previously (in the 1st semester ) we talked about the development of occlusion, we have something called the LEEWAY space (which is the difference between the buccal segment of permanent teeth and the buccal segment of deciduous teeth….deciduous teeth are larger of course), and this space is usually used to correct molar relationship.If we relieve crowding by utilization of this space then this is space management,, and in fact we use this space to relieve anterior crowding rather than to correct molar relationship.

If we are going to do space management, we should have three

criteria of the occlusion which are::

1- Class I molar relationship.Because if we have a 1\2 unit class II malocclusion then its better to use this space to correct molar relation ship which has not been corrected yet… I think that the DR means that if I have crowding in molars region and pt still have class I so we do space management to preserve class I

and correct molar relation ship.

So if it isn’t class I use the leeway space to correct the molar relationship which is a little bit more important than relief of anterior crowding .

2-crowding shouldn’t exceed the leeway space (mild crowding)

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If crowding is more than the leeway space that means that it's not enough to correct crowding, and you cant utilize a space for crowding when the leeway space is already smaller than the crowding itself.

3-the E's should be there..

The leeway space is (as you recall) the difference between the MD width of the 3, 4, 5 in the permanent dentition and the C, D, E in the deciduous dentition and the leeway space is mostly due to the difference between the E and the 5 (coz the D is not that bigger from the 4, the C is

even smaller than the 3)…

If the E is exfoliated that means that we lost most of the leeway space due to mesial drifting of the 6 (1st molar), and in this case we cant utilize it bcoz its already lost by mesial drift of the 6 and more loss of space means more crowding.

So if the E is not there then you can't do space management…P.S leeway space management is better to manage in the lower arch

than in the upper coz it's bigger in the lower…

NOW…how to do space management??

We have crowding, and this crowding should be ≤ 3.4 (which is the leeway space in the lower arch…mild) in the lower incisors area, we have

class I, we have the E still there…

How to use the space to relieve anterior crowding rather than moving the molars mesially?

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Here we use the term DRIFTODONTICS which means to drift (move) teeth…

In orthodontics we mean to push teeth into their places but in driftodontics we give the chance for the teeth to move to the normal position, and teeth are so nice that if they are given space during development of dentition they will move.. or drift.

Teeth are born (:-\) to be in a specific line of the arch, if no space crowding….if space is there as long as they are erupting then no

crowding ..

So what do we have to do in leeway space management??

We have to apply the term driftodontics to the incisors…so if we have crowding in the incisors ≤ 3.4, then we have to create a space for the incisors anteriorly..how?

By extraction of the E ?No bcoz if we extract the E then we are creating a space for the molars to move anteriorly and the incisors will not move.

By extraction of the D?No bcoz its somewhere in the middle

By extraction of the C?No its not applicable..

SO what shall we do?What we want is 1.5-2 mm space at each side of the incisors, so instead of extraction we can do TRIMMING..

What tooth shall we trim?The canine (C) .

Which surface?? mesial or distal or both?

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The more logic one is the mesial surface.

So by that we are doing inter proximal stripping for the C and then the incisors will relieve themselves.

Now after doing interproximal strippng.. will there be enough space for the permanent canine to erupt?No, it will be occupied by the crowded incisors..

So what to do??Trim the mesial surface of the D.. and this will also give the 4 (1st premolar) a chance to erupt..

Now will there be enough space for the 5 to erupt??Yes bcoz the E is much bigger than the 5..

After these questions the doctor wanted to comment about a piece of info said by one of our colleagues which is "space maintainer", and he said that space maintainers are used when we don’t trim, but when we extract , we preserve the space of the extracted tooth (and prevent the 6 from coming forward) by the space maintainers which are available in 2 types:

1-band and loop (band on the 6 and a loop on the C or D according to the extracted one)..

2-translingual arch (it runs from the 6 to the 6)..

Which one do you think we (them : orthodontists) use in space management?

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Band and loop?? No bcoz this will not change any thing, coz it prevents 6 from coming forward but doesn’t push the anteriors distally (and this is what we want), coz due to its touching the mesial tooth to the extraction site it will prevent them from going distally, and due to touching the distal tooth to the extraction site , it will prevent it from going mesialy.

So we use the translingual archThe 6's are prevented from going mesialy or forward, while the anterior teeth are free to move backward or distally (drift) and that is

what we want ..

So these are the two ways to manage space.. either extract the E's and place translingual arch, or slice the mesial surface of the deciduous C

or\and the D before the eruption of the permanent canine...

P.S we do space maintainers also in case of mild crowding..

Q: what about severe crowding (much more >3.4 mm)??

Here we do more tragic measure, instead of slicing the tooth, we do a kind of extraction that we call SERIAL extraction..

Q: what do we do in serial extraction??

Instead of trimming the mesial surface of the C or the D , we extract the C completely..

Now after the extraction of the C , the anteriors will move to occupy most of that space…

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Now (in the upper arch) the second tooth to erupt is the 1st premolar (4), we want to accelerate its eruption, and this is done by (wait for a while after extracting the C) extracting the D.

Q: Once we extract the D, what will happen??

The 4 will erupt to occupy the space of the canine.. so we then extract the 4 itself.

In serial extraction we are planning to extract permanent teeth..why??

Bcoz the crowding is so severe..

Q: why do we extract the D to accelerate the 4?Bcoz in the lower arch, the canine erupts before the premolars, and if the premolar erupts before the canine, then there will be crowding in the buccal segment or the 4 will get displaced SO extract the D, then the 4..

When do we do serial extraction? (indications)??

1 -when we have substantial crowding ( ≥10 mm).So we should have at least 10 mm's crowding, bcoz once we begin we will end up in extraction of the 4.If it wasn’t severe crowding, then we will end up in an excess space, so if mild crowding you leave it (no serial extraction), or space management (as mentioned previously)..

2 -age 8-9 years old.

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Why?? Bcoz the incisors are still erupting, so they still have a chance to spread if a space is found..

Any way.. there is a complication of the extraction of the C..in the last lecture I (DR) told you that if I extract a canine on one side there will

be a midline shift.. and if we extract both C's, what will the incisors do??They will spread (and that is something we want), BUT they will

collapse or tilt lingually and there will be some results that are: A- increased overjet and overbite

B-collapse of the lips.

So in order to perform serial extraction you need also 3 -normal arch relationship (not class II in particular)

4 -over bite should be normal or reduced because it will increase

after extraction ..

At the end of the day, we will have the 4 extracted, if the patient has a missing 5 then we absolutely don’t do serial extraction for him, and if we do, we will end up in 2 missing teeth in each quadrant and that is too much space.

So 5- all teeth should be there.

If third molars are absent, we still can do serial extraction, if the 5 is not there, don’t do serial extraction..

Some times we may find a patient with a badly damaged 6 , and in this case we will extract the 6's without doing serial extraction (no 4 extracted coz it will be too much if the 6 is also extracted).

If the canine is very close to eruption (keep in mind that the 4 erupts before 3 in upper..), and we cant accelerate the eruption of 4 (to erupt before the 3) here we don’t do serial extraction.

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The 1st premolar should be closer to erupt than the canine to perform serial extraction ..

When the laterals are still erupting in a crowded position, and the crowding is severe, we will extract the C's when the roots of the 1st deciduous molar (D) are half resorped, bcoz if early extraction of the D (b4 half the root is resorped), this wont accelerate the eruption of the 4 and instead of that, it will delay the eruption of the 4.. very late extraction of the D is not good also..

If we do that (extraction of the D when 1/2 of the roots resorbed), hopefully the 4 will erupt before the canine and we will extract it..

Disadvantages of serial extraction::

1 -increased over bite due to collapse of the lower labial segment.2 -lingual tipping of the lower incisors.

There was an info that the Dr told us, but then he said forget it.. any way I'll write it to you :: some people think that the presence of the canine helps in the transverse growth of the arch, but this is very debatable.

3 -lack of the esthetic fullness of the lips due to retraction of the incisors.

4 -if you have crowding in the form of incisors-in, incisors-out…all of that can be corrected.

BUT if the incisors are rotated.. and you give enough space, they will return to the line of arch, but they will still rotated.. so we don’t do serial extraction.

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Q: how many teeth do we extract in serial extraction??Three per quadrant, so 12 tooth in pt's mouth.

Q: when does serial extraction give you a perfect result at the end of the day?

1st there is no perfect result in that, but you may have a satisfying reduction of crowding, and if you are lucky enough, you will have perfect alignment of teeth.

For ex if you have severe crowding and you extracted the 2 premolars, then you will end in an extra space in the buccal segment..

So serial extraction requires the extraction of 12 tooth, and it wont give an ideal occlusion at the end..

Q: do you think that serial extraction is worth doing ??

In fact, serial extraction is fading away from the textbooks, its there as a history , and nowadays pts have dental insurance (that can be provided by qualified orthodontists without the need to be bothered by doing serial extraction, knowing that the pt will need a fixed appliance later on) in most of the countries that adapted the serial extraction measure, so its debatable, and frequently done by people with low Socio Economic Status.

Dr: can any one of you give me an advantage of serial extraction over fixed orthodontics (knowing that the pt will need it later on)??

P.S by the way that was a Q that is worth of a 1 EXTRA MARK

Here are the answers that some of our colleagues said:

One said : in fixed ortho there will be destruction of the PDL

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Dr: no, there won't be if the patient cleans his teeth and committed to the OHI's .

Another student : success rate is moreDr: no they are the same..

Another student : teeth may relapse in the fixed orthodonticsDr: yes that is true.. and this is what we don’t see in serial extraction bcoz we extract to get a space and we don’t push teeth..

In serial extraction the teeth move unwillingly to the space, so less chance to relapse after treatment, while in fixed teeth are pushed to their places, so they may relapse after the end of the treatment.

1st molar extraction

This is the 3rd method of managing crowding..One of the patients that came to my (dr) clinic complaining of spacing (picture below) ,

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Q: how many molars does he have?

5 molars, one 1st molar and four 2nd molars..

Dr showed us a photo shows that when we have an early extracted lower 1st molar, there is a good chance for the 2nd molar to come forward and take the place of the 6, thereby avoiding future prostheses later on, and if we had crowding particularly in the buccal segment (no space for canine or premolar) we will get enough space for the premolars to align themselves just by extraction of the 6..

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What are the indications of 1st molar extraction ??

we don’t think of first molar extraction unless we have a poor prognosis either endodontic treatment or restoration..

you are in your clinic one day (hopefully), a 9 year old kid presented to you with a badly destroyed lower 6, you say I can treat it by endo and SSC and later a permanent crown, but I think (dr) its better to do extraction of the 6, and the 7 will have the chance to get the place of the 6,

and hopefully later on the 3rd molar will erupt in the place of the 7…

what factors decide which way to choose restorative or surgery (simple extraction)??

we have factor that if are present then we choose to extract…1-poor prognosis of the 6 (at least one of them)..

Never think of extracting the 6 if no caries was found..

The problem of the extraction of the 6 is that you might not have a good contact between the 2nd premolar and the 2nd molar which is the most difficult thing to judge, but if we have crowding in the buccal segment particularly in the area of the 6 then we have two advantages of extracting

the 6:

A-relieve crowding

B-some of the space will be taken by the crowded premolars, so the 7 has to travel smaller distance rather than incase where we don’t have crowding (coz as we said part of the space will be occupied by the crowded premolars smaller distance for the 7).. so its better to have crowding..

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Now , for the 2nd molar to come forward, it shouldn’t have erupted yet and its root development shouldn’t exceed 1/2 of it.Bcoz if the 7 erupts and the 6 extracted later, there is no chance for the 7 to move forward, if > 1/2 of the root of the 7 has been formed, then its better for you to do restorative treatment (6) rather than extraction.

If there are any missing teeth (2nd premolars), we wont extract the 6's, and unlike serial extraction if the 3rd molar isn’t there we cant also extract the 6's coz you will leave the pt with only one molar..

So 2- all teeth should be there including the 3rd molar.

The effects of extracting the 6's will be :Increased over bite and over jet (like serial extraction).

3 -normal arch relation ship4 -over bite should be normal or reduced coz it will deepen after

extraction.

After extracting the 6, the 5 will go distally, it will hit the 7 then it will go up, so distally inclined premolars are not a trouble if the 6 is present (mesial surface of the 6).

But if the 6 is extracted, the 5 will go further back to hit the 7 and then go up (more distance travelled)..

If you have a badly destroyed 1st molar, before doing restorative treatment, see all the factors that indicate extraction if present or not, hopefully the 7 will come forward and take the place of the 6, and if you have crowding in the buccal segment or the anterior (lower arch), it will be relieved, but if severe anterior crowding, it will not be relieved.

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What are the advantages ??

1 -no need for further prostheses, bcoz the 7 will take the place of the 6..

2 -reduction in incisors' crowding especially in the lower arch .

3 -complete elimination of crowding in the premolar area .

4 -less chance of third molar impaction.

What are the disadvantages ??

1 -uncertainty of the final contact between the 5 and the 7.. Q: where do you think this uncertainty is found more, in the

upper or in the lower arch???

Its in the lower, while in the upper , mesial drifting of the teeth is much easier and thus space loss is also easier (than the lower).. so the 7 in the upper arch will move easier.

Now lets talk a little bit about space loss…

Q: How does the space disappear after the 1st molar extraction??

It differs between the upper and the lower arch..In the upper : once you extract the 6, the 7 will start to move or drift and some times the 7 will erupt just distal to the 5, i.e the 7 started to move in bone and erupted just distal to the 5 due to absence of the 6.

In the lower arch : the scenario here is not the same

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So what happens is : the 7 is not smart enough to move when 6 is extracted so it will stay in its place inside bone, and it will start to move when its close to eruption, so space loss pattern is not the same..

Q: why is that important to us??

If we extract the lower molar only, the upper opposing molar will supra erupt, the adjacent lower 7 will start to move mesially, but it wont accomplish this bcoz it will be locked in the upper supra erupted 6 (in the photo below).. if the opposite happens .. nothing will get locked..

If we extract in the lower and we aim for space closure, then we have to extract in the upper and this is what we call compensatory extraction.

But if we extract in the upper we don’t need to extract in the lower..

Another type of extraction is the balanced extraction : to extract the same tooth (molar for ex) on both sides the left and the right..to preserve the midline.

In the upper arch as we said after extraction of the 6, the 7 will start to move forward and will take the space of the 6, the 4,5 and the anteriors

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will never go distally to fill the space (so there will be no midline shift), so when you extract the upper 6 there is no need to do balanced extraction or compensatory..

But if in the lower arch, if you extract the 6, there will be a shift in the midline, so balanced and compensatory extractions are needed.

So extraction of four 6's (in case of the lower), this means four uncertainties about the contact between the 5 and the 7.

Q: do we accept a small shift in the midline for the sake of two sound permanent teeth???????

Yes, bcoz by this we save ourselves two points of uncertainties .So its not very wise to extract the four 6's unless they are badly heavily damaged.

Q: If you have a pt with severe crowding in the anterior segment (P.S crowding in the anterior segment will be reduced but not

eliminated), which is safer to extract in the upper or the lower??Knowing that in the future the pt will need ortho treatment and

a space??

In the lower is better, bcoz the space is very difficult to close, and even if closed, this would be due to distal movement and not full occupation of the space.

In the upper it’s a risk, if we are going to extract the upper 6 in case of severe crowding, the space will close completely just by the eruption of

the 7…

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So if you are going to do later treatment, further space is needed, further extraction is needed..

So we do dressing for the upper 6, which means to maintain the 6 as much as possible until the 7 erupts, and after you extract the 6, you can do ortho treatment or space maintainer.. and don’t extract the upper 6 if you have anterior severe crowding.

If you have crowding in the buccal segment, you can extract bcoz there is a chance to relieve that crowding..

Thank you

Done by : Razan M. Alshehab 28-02-2009

Any feed back is truly welcomed..

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