normal dental development

Question 1

number/ types of teeth in decidious dentition

Answer 1

20

2 incisors, 1 canine, 2 molars

Question 2

number/ types of teeth in permanent dentition

Answer 2

32

2 incisors, 1 canine, 2 premolars, 3 molars

Question 3

palmer system

Answer 3

draw box
primary teeth A-E
permanent teeth 1-8

Question 4

FDI system

Answer 4

primary teeth 1-5
permanent teeth 1-8
quadrants numbered 1-8
used in europe, good to type

Question 5

eruption of primary dentition

Answer 5

6-9 months: lower As then upper As
7-10 months: lower Bs then upper Bs
12-16 months: Ds
16-20 months: lower Cs then upper Cs
23-30 months: lower Es then upper Es

Question 6

when is root formation of primary teeth completed

Answer 6

12-18months after eruption

Question 7

describe occlusion at birth 3

Answer 7

gum pads occlude distally
anterior oval opening to allow sucking
fleshy labial frenum

Question 8

describe occlusion at 6-10 months

Answer 8

maxillary incisors erupt labial to mandibular incisors (class 1 occlusion)

Question 9

describe occlusion at 36 months 4

Answer 9

• incisors vertical and spaced
• deep overbite
• anthropoid spaces mesial to max canine and distal to mandibular canine
• flush terminal plane (distal edges of Es in line)

Question 10

describe occlusion at 6 years

a. primary dentition 3
b. mixed dentition 4

Answer 10

a. teeth same but child grows –>
- decreased overbite
- spacing of anterior teeth
- attrition of incisors

b. -eruption of 1st permanent molar
- mesial migration of primary molars
- anthropoid spaces close
- permanent molars in class 1 or half class 2 relationship

Question 11

eruption of permanent dentition

Answer 11

6-7yo: lower 1s,6s --> upper 6s --> upper 1s
7-8yo: lower 2s
8-9yo: upper 2s
9-11yo: lower 3s
10-12yo: 4s --> 5s
11-12yo: upper 3s
11-13: 7s
17-25: 8s
MOLARS AT 6,12,18

Question 12

when is root formation of permanent teeth complete

Answer 12

2-3 years after eruption

Question 13

describe occlusion at 7-8 years 3

Answer 13

• max central incisors erupt spaced and more proclined and primary max central incisors
• max lat incisors often distally inclined
• max incisors labial to mandibular

Question 14

define leeway space

Answer 14

difference between combined mesiodistal width of primary canine and molars and permanent canine and premolarss

Question 15

leeway space for

a. max arch
b. mandibular arch

Answer 15

a. max arch: 1.5mm

b. mandibular arch: 2.5mm due to larger 2nd molar

Question 16

describe occlusion at 9-12 years 2

Answer 16

• primary canines and molars exfoliate, permanent molars drift mesially in to leeway space to form class 1 relationship
• max permanent incisors should be palpable buccally at 10yo

Question 17

describe occlusion at 11-13 yrs 4

Answer 17

• incisal spacing reduces as max canines erupt, guided by distal angulation of max 2s –> pushes central incisors together
• all primary teeth efoliated
• 1st permanent molars in class 1 relationship
• second permanent molars erupting

Question 18

most common natal/ neonatal teeth

Answer 18

lower incisors

Question 19

tx of natal/ neonatal teeth

Answer 19

remove if cause aspiration risk/ interfere with feeding/ traumatise soft tissue

Question 20

why is it important that canines palpable buccally at age 10

Answer 20

if too palatal, may cause resorption of roots of incisors

Question 21

what happens if primary teeth lost

a. very early
b. slightly early

Answer 21

a. very early: gums heal over –> delayed eruption of permanent teeth
b. slightly early: permanent tooth erupts early

Question 22

when should you be suspicious of tooth not erupting when contralateral counterpart has

Answer 22

6 months