Development of the Occlusion

Question 1

Key points about primary dentition

Answer 1

Eruption times vary +/- 6 months
Calcification begins 4-6 months in utero
Root formation complete 12-18 months after eruption

Question 2

Sequence of eruption of primary teeth

Answer 2

a-b-d-c-e

Location Mandible. Maxilla
A. 10mnths 8mnths
B 11mnths. 13mnths
C 19mnths 20 mnths
D 16mnths 16 mnths
E 29mnths. 27mnths

Question 3

2 1/2 years

Answer 3

primary dentition established
1 incisors are more vertical than secondary
primate spacing

Question 4

2 1/2 – 5 1/2 years

Answer 4

increase in spacing due to inc in arch width
occlusal attrition leads to edge-edge incisal relationship

Question 5

significance of carious molars

Answer 5

extraction of 6s doubles the tx time and halves the prognosis
space closure in the lower arch is poor
space closure in the upper arch is good

Question 6

hypodontia

Answer 6

4-6 % congenital absence
most common:
Mandibular 5s
Maxillary 2s
Maxillary 5s
Mandibular 1s

Question 7

Significance of supernumerary teeth

Answer 7

1-2% incidence
Maxillary incisor region (mesiodens)

Question 8

Sequence of eruption of permanent teeth

Answer 8

Mandibular. Maxilla
1 7-8yrs 6-7yrs
2. 8-9 7-8
3. 11-12 9-10
4 10-11 10-12
5. 10-12 11-13
6 6-7 6-7
7 12-13. 11-13
8 17-21 17-21

Question 9

Components of dental arch development

Answer 9

arch length
arch width
arch height

Question 10

arch length

Answer 10

increases slightly on eruption of the permanent incisors due to jaw growth and increased proclination of permanent incisors
inc in arch length to accommodate additional permanent mlars

Question 11

arch width

Answer 11

little change to the primary dentition
increases on eruption of the permanent incisors

Question 12

arch height

Answer 12

juvenile occlusal equilibration - teeth have erupted into the occlusion. they continue to erupt at a slower pace to match vertical skeletal growth.

adult occlusal equilibration - once the adolescent growth spurt has passed the teeth continue to erupt to compensate for wear and the continued vertical skeletal growth.