8-chronologylecture-140123080327-phpapp02

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Condition of Teeth
At Different Ages
Generally:
1- Teeth begin its calcification long before its date
of eruption.
1
2- When tooth erupts the crown and about 3
of
the root is completed.
3- Roots are completed after eruption by 1-1.5
years (for deciduous) and after eruption by 3
years (for permanent).
4- Roots of deciduous teeth begin resorption 3
years before shedding.
Chronology Of
Deciduous
Teeth
:For deciduous teeth
• Enamel organ for deciduous teeth appears from 7-9
w.i.u.
• Beginning of calcification of deciduous from 4-6 m.i.u.
• Deciduous Canines erupt after deciduous1st molars.
• Mandibular teeth erupt before maxillary teeth.
• Shedding occurs at the same date of eruption of
successors.
• Shedding of deciduous teeth occurs from 7-11 years
Lower before upper
A B
A B
5
3
C
C
D
D
4
E
E
2
1
4.5
C
C
D
D
E
E
6
7
6
8
7
18
16
14
12
24
20
5
.
1
3
2.5
3
years be
fore shed
d
4
5
A
A
B
B
ing 3-
Beg. Of Eruption
Root
Beginning
(m.)
calc. (m.i.u)
completed (Y) of root res.
Chronology Of
permanent
Teeth
For permanent
teeth:
At birth, first permanent molar is the only permanent *
. tooth showing evidence of calcification
Dates of eruption of permanent incisors is the same as *
.deciduous incisors but in years
1
1
. Premolars start calcification between 1 2 & 2 2 y*
.Lower teeth sequence of eruption is 1 2 3 4 5*
.Upper teeth sequence of eruption is 1 2 43 5*
.Lower teeth erupts before upper opposing teeth *
First, second& third molars erupt at ages of 6,12,18 *
. years respectively
3-4
10-12
3-4
4-5
years
3-
1
1
2
2
3
3
7
6
8
7
11
9
years
3+
Beginning
Crown
Eruption
Root
.of calc completed )years( completed
(month)
Beginning
Crown
Eruption
Root
.of calc completed )years( completed
12
134
2
1
22
10
10
11-12
11-12
years
3+
1
years
3-4-
4
4
5
5
Beginning Crown
Eruption
Root
.of calc completed )years( completed
3y
8y
6y
12y
18y
years
3+
At
birth
years
3-4-
6
6
7
7
8
8
ML cusp
Separate
cusp
Less than1/2
Occ.S
Cusp
tip
½
crown
• Permanent teeth ML cusp of lower 6.
• No erupting teeth
months 6
cusp tip
Crown&1/4 root
most of crowns formed
C&D&E
start eruption
separate cusps of 6
Incisal 1/3 of 1&2
3
2
1
6
E
D
C
B
year 1
A
5
4
3
2
1
B
A
6
E
D
C
years 2
years 3
small part
of 4&5
More than ½ crown
of 1&2 formed
separate
cusps of 7
All deciduous
teeth erupted with
fully formed teeth
crown of 6
completed
crown 3½
crowns of
3&4&5 formed
is erupted 6
less than 1/3 of the
root formed
crown&1/3 root
formed
Root of lower A
resorped
crown of 7 not
completed
E no resorption
B&C&D some
amount of
resorption
years 7
years 7-8
5
7
4
3
6
2
E
D
1
C
B
years 7
not yet erupted &less 5&4&3
than 1/3 of root formed
Calcified separate 8
cusps are formed
C&D&E most of
their roots
resorbed
crown& less than 7
1/3 root formed
root of 6
completed
is erupted their 2&1
root completed
All permanent teeth
erupted except 8 .
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