8. eruption

8/6/2019 8. Eruption

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ERUPTION


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AGE OF ERUPTION

Deciduous Teeth

A B C D E

Maxillary 7 months

9months

18months

14months

24months

Mandibular 6months

7months

16months

12months

20months


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Sequence oferuption:

1. Centralincisor

2. Lateralincisor

3. Firstmolar

4. Canine

5. Secondmolar


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In general:

1. Lowerteeth erupts firstcomparedto

the upperteeth.

2. Girlsteeth erupts firstcomparedto

boys.


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Exfoliation

castingaway

orthrowingoffofthe surface ofthe

deciduousteeth

following eruption.


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Resorption

the gradual

degenerationof

apart & the

removalofsuch

fromthe body.


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Succedaneous teeth permanentteeth

that followsthe guide tooth.

Assessional teeth theyare the 1st,2nd

and3rd molars.


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Permanent Teeth

CI LI C 1PM 2PM 1M 2M 3M

Maxillary 7-8y/o

8-9y/o

11-12y/o

10-11y/o

10-12y/o

6-7y/o

12-13y/o

17-21y/o

Mandibular 6-7y/o

7-8

y/o

9-10

y/o

10-12

y/o

11-12

y/o

6-7

y/o

11-13

y/o

17-21

y/o


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Stages of Tooth Development:

1. Initiation

2. Budstage

3. Capstage/Proliferation4. Bellstage /Morphodifferentiation

5. Apposition

6. Calcification

7. Eruption


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Nollas Calcification of Teeth

(Growth Stage)

0 - Absence ofcrypt

1-

Presence ofcrypt2 - Initialcalcification

3 - 1/3ofcrowncompleted

4 - 2/3ofcrowncompleted5 - Crownalmostcompleted


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6 - Crowncompleted

7 - 1/3ofrootcompleted

8 - 2/3ofrootcompleted9 - Rootalmostcompletedwith

openapex

10 - Apical endofrootcompleted


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X-ray reading for in-between stages:

y 0.2 ifreadingisslightlygreater

thanthe illustratedgrade/stage but

notasmuchashalfwaybetweenthatstage andthe next.

( Stage 7 = Stage 7.2 ) more thantwothirdsofthe rootiscompleted.


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y 0.5 readingthatliesbetweentwo

grades/stages.

( bet. Stage 7&8 = Stage 7.5 )

between 1/3and2/3ofrootis

completed


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PRE-DENTAL JAW

RELATION

> establishedbefore

the eruptionofthedeciduousteethapproximately

3-5 months

intrauterine & 5-6monthsafterbirth.


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> Characteristics:

1. Presence ofgumpads,absence of

teeth,maxillarygumpadwidermesio-

distallythanthe mandibular&

maxillarygumpadpositionedmore

anteriorly.


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2. Coronoid processhigherthanthe

condylar processbecause ithasnot

obtaineditsgrowth & development

fully.

3. Gonion orangle ofthe mandible is

obtuse. (Adult acute)


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4. Absence ofalveolarprocess.

5. Sitesofmandibularbone growth:a) condylar process

b) bodyofthe mandible


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6. Presence ofinterocclusal space or

gap thisisaspace betweenthe

maxillary & mandibulargumpads.

7. Presence of20setsofdeciduous

developingtoothbuds.


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DECIDUOUSDENTITION

> establishedwhenthe deciduousteeth

are presentinthe

oralcavity from6

months- 5 years.


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>Characteristics:

1. Presence ofdevelopmentalspaces

foundbetweenthe deciduousteethto

accommodate permanentteeth.

2. Presence ofprimate oranthropod

spaces fromthe mesial ofthemaxillarycanine & distalofthe

mandibularcanine.


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3. There isan endto endmolarrelation

orcusptocuspcontactbetween

molars,because the mandible hasnotyetattaineditsmaximumgrowth.


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There is the production ofterminalflush plane (straight plane observed

among the deciduous molar due to its

end to end relationship, as themandible grows anteriorly & inferiorly,

normal occlusion results due to

attainment of mesial step).


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MIXED DENTITION/

TRANSITIONALPERIOD

>startswiththechange from

temporaryto

permanentdentitionwhichcovers from

6-14yearsofage.


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>dividedintothree stages:

1.E

arly = 6-8 years

2. Middle = 8-10years

3. Late = 10=14years


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> Characteristics:

1. Uglyducklingstage results fromthemovementof eruptingpermanentmaxillaryincisorstowardsthe distalordistal flaring.

(Thisoccursbetween 8-12years.)


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(Distal flaring distalinclinationofthe

eruptingteethhence,there isthe

presence ofdevelopmentalspaces

betweenteeth. Whenthe permanentcanine emerge,the incisorswillgoto

theirnormalposition & the distal

flaringsubsides.)


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4. Incisorsremaintobe distally flaringdue tothe followingreasons:

a) abnormalMD widthofteethb) abnormalattachmentoflabial

frenum

c) presence ofsupernumeraryteeth


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PERMANENTDENTITION

>coversage15 andabove


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> Characteristics:

1. Normalsurface tosurface contact

normaloverlappingofthe incisors.

2. Normalcuspto fossa contact.


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3. Normaltriangularridge to embrasure

contact.

4. Normaltriangularridge togroove

contact.


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> Factorsaffectingthe establishment

ofnormalocclusion:

1. Muscularpressure.

2. TMJrelation.

3. Proximalcontactofthe teethinthe

same dentalarch.

4. Axialinclinationofthe teethinrelationtoocclusal forces.


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5. Harmonyinsize & shape ofdento-alveolararches.

6. Inherent forcesofgrowth.

7. Atmosphericpressure(pressure of the

mouth=pressure in all of the airways)

8. Forcesofinclinedplanesofteeth.

9. Morphologyofteeth.


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8. eruption

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