CFD10 : Dental chronology

Question 1

What is eruption?

Answer 1

tooth moves from bone into the mouth into occlusion

Question 2

what forms first out of the crown and the roots?

Answer 2

crown

Question 3

what is calcification?

Answer 3

hard tissue appearing in the developing tooth

Question 4

why learn dental chronology?

Answer 4

Parameters:
– calcification start 
– crown complete 
– eruption
– root completion

Question 5

what is visible radiographically?

Answer 5

• calcification start

- crown complete

Question 6

why is learning eruption important?

Answer 6

• assess correct “dental age”

- detect abnormalities in eruption

Question 7

Describe the gum pads at brith.

Answer 7

– over A‐D’s at birth
– separated by tongue
– usually +ve Over Jet
– u.e. teeth crowded
– rapid growth in 1st year

Question 8

When does tooth development start in deciduous dentition?

Answer 8

6 weeks i.u

Question 9

when do tooth germs form in deciduous dentition?

Answer 9

3rd-4th month i.u

Question 10

when does the first deciduous tooth erupt?

Answer 10

6-7 months

Question 11

when is the deciduous dentition complete?

Answer 11

2.5 years (approx)

Question 12

What is the order of deciduous eruption?

Answer 12

• 6 months - lower A’s
• 7 months - upper A’s
• 7 months - lower B’s
• 8 months- Upper B’s
• 12-16 months - Ds
• 16-20 months - C’s
• 20-30 months - E’s

Question 13

why do D’s erupt before C’s?

Answer 13

stabilise the occlusion

Question 14

when is initial calcification (in -utero) of deciduous dentition?

Answer 14

• 3-4.5 months - A’s
• 4.5 months - B’s
• 5 months - C’s
• 5 months - D’s
• 6 months - E’s

Question 15

when is crown completion of deciduous dentition?

Answer 15

after birth:

• 4 months - A’s
• 4.5-5 months - B’s
• 9 months - C’s
• 6 months - D’s
• 10-12 months - E’s

Question 16

when does root completion of deciduous dentition occur?

Answer 16

1- 1.5 years after eruption

Question 17

what is the variation in eruption ?

Answer 17

Note - much variation in eruption dates e.g A’s can appear as late as 1 year old

Question 18

what are deciduous dentition features?

Answer 18

• to (approx) 6 years
• frequently incisor spacing
• anthropoid (primate) spaces
• flush distal edges of E’s
• attrition
• permanent dentition developing

Question 19

what are anthropoid or primate spaces?

Answer 19

bigger spaces between the upper A and the C and the lower C and D

Question 20

what is attrition?

Answer 20

teeth are worn down , lower teeth drift forward and produce medial step

Question 21

when does eruption of permanent dentition commence?

Answer 21

age 6

-start of the mixed dentition

Question 22

what happens when permanent teeth erupt?

Answer 22

deciduous teeth start to be shed

Question 23

Do you have to lose all deciduous teeth for permanent teeth to come in?

Answer 23

No - difference in accessional and successional teeth

Question 24

what permanent tooth erupts first?

Answer 24

usually 6’s erupt first then lower 1’s

Question 25

What is the order of permanent eruption?

Answer 25

• 6-7 years- 6s
• 6-7 years - lower 1’s
• 7-8 years - lower 2’s
• 7-8 years - upper 1’s
• 8-9 years - upper 2’s
• 9-10 years - lower 3’s
• 10-12 years - 4’s
• 10-12 years - 5’s
• 11-12 years - upper 3’s
• 12-13 years - 7’s
• 17-21 years - 8’s

Question 26

what can u feel high in the sulcus upper the C?

Answer 26

upper 3

Question 27

what is the 1st signs of calcification?

Answer 27

-1st signs of calcification :
6's - around birth or just before
7's- 2.5 - 3.5 years 
8's - 7-9 years (upper) , 8-10 years (lower)
-rest of teeth during first 2 years

Question 28

when are the crown completion of permanent dentition?

Answer 28

• 1’s and 2’s - 4-5 years
• 3’s - 6-7 years
• 4’s - 5-6 years
• 5’s - 6-7 years
• 6’s - 2.5-3 years
• 7’s - 7-8 years
• 8’s - 12-16 years

Question 29

when does root completion in permanent dentition occur?

Answer 29

2-3 years after eruption

Question 30

what are eruption problems?

Answer 30

• eruption should be symmetrical
• delays may indicate a problem
• natal teeth - early eruption @birth
• submergence -ankylosis(teeth fuse to bone)

Delayed eruption: see next card

Question 31

what are problems with delayed eruption?

Answer 31

• Down’s syndrome
• delayed deciduous resorption due to trauma
• dilaceration (teeth form with angled root
• supernumeraries
• early deciduous loss and bone formation
• abnormal path of eruption
• impaction
• crowding
• congenital absence (upper lateral incisors not uncommonly missing)