pedo v script 1management of developing occlusion

8/11/2019 Pedo v Script 1management of Developing Occlusion

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Dr started the lecture explaining the course and the distribution

of marks on both semesters; you can find all the information on

the syllabus

Let's start our lecture..

This lecture will be divided into 4 parts:

Before we go into the details about space management we

have to understand and remember few basic things:

Slide #1:

Dental occlusion undergoes significant changes starting from

birth until Adulthood.

We start from edentulous phase >> then primary dentition

phase>> then we go into mixed dentition phase>> then the

permanent dentition

Primary dentition: phase start at 6 month of age and end at

usually 2.5 to 3 years of age, in this age all of primary teeth will

be erupting.

Mixed dentition:Starts at 6 years of age, the 1st

tooth that's

going to exfoliate is thelower central incisor. The 1st

tooth to

erupt is theupper 1stmolar and the central incisor, usually at

the same time, but in some cases the permanentmolarerupts

before the incisorand in the other cases the opposite.


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These stages that we talked about will occur in a timely and

orderly fashion if any changes happened on the timing or the

order in which the eruption of teeth occur the consequences

will be a disruption of the spaces that exists and eventually we

will have a spaceloss. Some teeth will grow out of the arches

and the permanent teeth will not have a proper space to erupt.

Slide #2:

There are normally existing spaces in the dental arches.

Primate Space: This is the space that is mesialto the canineon

the upper archand distalto the canineon the lower arch.

Leeway Space: Is the difference in size between the primary C,

Dand E, and the permanents 3, 4 and 5.

*Which one is bigger?

The primary C, D and E.

(The Mesiodistal dimension of C, D and E is bigger than the

permanents, and thats why they create a little bit space to

accommodate the erupting permanents teeth)

Incisor liability is: (At the age of 7 -8 the eruption of lower

incisor age the lower Incisor of permanents are usually bigger

than primary (the mesiodistal of primary are smaller)

So we reach a stage during eruption in which there is no space

for permanents teeth to erupt and it looks like that the


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permanent erupting in a slightly crowding position. This mild to

moderate crowding which occur between 78 ages is called

incisor liability.

This mild to moderate -around 2 mm crowding- is relieved by

itself "dont need treatment" dueto many factors:

One of these factors is that the permanent teeth erupt in a

more protruded position than the primary teeth, so this

will give about 1-2 mm extra space.

The other factor is the primate spacewhich is "distal to

the canine", this space will be utilized when there is

eruption of central and the lateral by the distal drifting of

the canine.

Another factor is the growth of mesiodistal width of the

arch (intercanine width ) increased about 1-2 mm

Those factors together compensate the change between the

size of permanents and primary teeth so it resolves mild to

moderate crowding by itself with no treatment needed.

**If there is more crowding (moderate to severe ) the

crowding won't be resolved by itself, it won't be resolved by the

growth of the arch because the intercanine growth will stop at

9 years of age, so the patient's going to have crowding teeth.


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Primary Molar Relationship:

Mesial step.

Distal step.

Flush.

Class 1, 2 and 3 in angles relationship for permanents molar

The Importance of knowing the primary molar relationship is

that the relation will tell us how the permanent molars will

erupt, so if I have a mesial step then most probably the molars

will erupt either be a class 1 or end to end .

If they erupt end to end after the loss of primary molars then it

will be class 1, how?

By the late mesial shift of the permanent first molar.

Slide 4:

Now sometimes there will be arch length deficiencies;

There will be a crowding and it happens for 2 general reasons:

1-Arch length is too small to accommodate the size of the

teeth, or2- We have an adequate arch length but some

environmental factors occur, like the loss of primary teeth

at early stage so we end up having deficiencies of the arch.


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And how the arch deficiencies or discrepancy can be

diagnosed?

Slide #5:

(Signs of arch deficiencies)

1-

If we have an early exfoliation of primary canine while the

erupting of lower lateral incisor, so we dont have enough

space for incisor to erupt in proper position and thats

why the lateral will cause the exfoliation of primary

canine.

2-If the incisor is totally blocked out of the arch either labial

or lingual; because of this blocking, there will be gingival

recession specially when the blocking of the arch is labial;

thus, there will not be enough support from gingival

tissues and we end up having gingival recession in that

area.

3- Some researches says that the lack of interdental

spaces in primary dentition is found to be a sign of

deficiency on the arch of side of crowding.

But this is unreliable sign since Baume stated that 9 out of

16 individuals with no interdental spaces in the primary

dentition did not have any crowding in the permanent

dentition, so this is not a reliable sign even though some

authors said that the lack of interdental spaces means the


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teeth will be crowded and doesnt have adequate space

for permanents teeth to erupt.

Slide #6:

Why do we get space loss?

The causes of space loss are different between anterior

and posterior teeth.

It mightsometimes- be an environmental factors that

reduce the mesiodistal width of primary dentition, some

of these factors are:

Interproximal caries.

Poor restoration.

Natural wearing of the teeth.

Premature loss of primary teeth due to:

The loss of primary anterior teeth is usually

attributed to trauma rather than tooth decay.

But on posterior teeth the majority of teeth loss due

to decay rather than trauma.

Loss of primary teeth early due to ectopic eruption of

permanents tooth.

Maybe due to congenital disorder that will cause

premature exfoliation of teeth.


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Or maybe premature re-sorption due to arch length

deficiency, like early exfoliation of the canine during

the eruption of the lateral.

Now...

In order to understand if we want to use space maintainer or

not, or to understand either we're going to have space loss or

not, we have to understand how the development of

malocclusion occurs;

The tooth is hold in its position due to different forces in

different directions, and those factors are:

Occlusion from opposing tooth.

Periodontal ligament holding the tooth.

The adjacent teeth.

If the one of these forces is lost, there will be imbalance and

will either over-erupt if there is no opposing tooth or tilt misally

or distally according to the side of the force.

The general factor that influence the development ofmalocclusion when the tooth is extracted prematurely

Depends on:

The presence of abnormal oral musculature.


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The presence of oral habits.

Existing malocclusion.

And stages of dental development.

Now ..

If, for instance, we have a child with a thumb sucking

habit, in thumb sucking habit the force will be protrusion

on the upper teeth and retro clination on the lower teeth.

If we lost D in the above case, with this type of force (of

thumb sucking ) the lower incisors will even retrocline

more.

So (distal movement to the canine and incisors) into the

extraction space, so this child who have habit and losing

tooth on lower arch he will lose the space quicker;

because the force (thumb) will cause the teeth to move(extra force) towards the extraction side>> so will lead to

increase the retroclination of lower teeth and distal

movement for the canine into the extraction space.

*If the patient has crowded teeth, for example, and we

remove the tooth.

Doyou think that the teeth will try to get a better position

by drifting into the extraction space? Yes.


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So the space loss increase when the patient already have

a malocclusion or crowding, but when the patient spaced

originally so will not have a space loss for the area

because there is no forces causing the tooth to go into or

to drift or move into the extraction space.

The abnormal musculature.

They said that the patient who have a High tongue

posture coupled with a strong mentalis muscle may

damage the occlusion after the loss of a mandibularprimary molar because the collapse of the lower dental

arch and distal drifting of the anterior segment.

One example is when we have oral habit, this habit will

increase the collapse of the anterior segment and drifting

of the teeth more distally into the extraction side.

The existing malocclusion.

*the patient who have Class II, division 1 and there

is loss of the tooth prematurely, the class 2 div 1 will

be more severe that because of in class 2 div 1 the

upper incisor is proclined and the lower incisor in

most cases is either in normal inclination or

retrocline.


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If we lose a primary tooth we will have drifting of

the lower segment so the severity of class 2 will be

increased.

*Class III molar relation increased in patients with

premature loss of mandibular second primary molar.

*The class 2 div 2 malocclusion will have greater lip

forces that maintain the retroclination of the upper

incisors and, thus, lip forces may contribute to

increased space loss should a primary molar loss

occur.

So the class 2 and 3 will increased in there severity

if we have premature loss of primary tooth

The stages of dental development.

In general we will have more space loss if there is active

eruption of the permanent molars.

*On the x-ray in the slide.

We have an early loss of E if this loss before the 4 years of

age , we will not have a space loss in this up to age 4.

But from age 5 -6 when we have an active eruption of the

permanent 1st

molar there is no tooth to guide its

eruption so it will drift more misally, which means during

the active eruption we will lose a lot of space if we dont

have a space maintainer.


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So during the active eruption of adjacent teeth more

space is lost.

*Miyamoto, Chung and Yee (1976) studied 255 children

aged 11 years and older to observe the effects of the early

loss of the primary canines and first and second molars on

malocclusion of the permanent dentition.

They found that:

Children who had a premature loss of one or more

canines or molars more commonly received orthodontic

treatment for the permanent dentition. This Orthodontic

treatment need was increased with the number of

prematurely teeth that were lost, the frequency of

orthodontic treatment in children who had lost one or

more primary teeth was three times greater than the

control group.

As a conclusion, if you loss primary teeth prematurely you will

end up having more problems later on and orthodontic

treatments will be needed, and, the number of teeth lost will

increase the severity .

The reference of this lecture is from slides and MacDonaldsbook

DONE BY:

Sara Al Omari

pedo v script 1management of developing occlusion

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