Primary dentition anatomical differences and implications

Question 1

Primary dentition

Answer 1

20 primary teeth (32 secondary teeth)
Incisors, Canines and Molars
No premolars
primary molars are replaced by premolars
secondary molars erupt distal to Es

Question 2

Primary occlusion

Answer 2

Each tooth occludes with 2 teeth in opposing jaw
Mandibular Es are larger than maxillary Es
Distal surfaces of maxillary Es project slowly over distal portion of the mandibular E (25%)
Maxillary arch is larger than mandibular arch of teeth
primary teeth are more upright
mandibular incisors occlude with palatal surface of maxillary incisors
anthropoid space – distal to mandibular C, mesial to maxillary C

Question 3

Primary dentition

Answer 3

mandibular teeth erupt first
symmetrical pattern
incisors, Ds, Cs and Es
All primary teeth by 30 months

Question 4

Natal teeth

Answer 4

Present at birth

Question 5

Neonatal teeth

Answer 5

Present within 30 days

Question 6

Late eruption

Answer 6

Missing teeth

Question 7

Differences between primary and permanent teeth?

Answer 7

Crowns are smaller, whiter and have thinner enamel/dentine layers. Enamel rods slope occlusally.
The pulp horns are closer to the outer surface.
Roots flare as they approach apex.

Question 8

What are the characteristics of primary incisors?

Answer 8

Crowns are shorter, have a marked constriction at cervical margin and rarely have mamellons.
Narrower M-D than secondary incisors

Question 9

What are the characteristics of primary canines?

Answer 9

Large crown
Bulge at cervical constriction
Symmetrical cone shape or mesial slope longer
Cusp tips wear rapidly

Question 10

What are the characteristics of primary molars?

Answer 10

Narrower occlusal tables
Broad contact area in primary dentition
Higher pulp horns in primary
Roots are slender, narrow M-D
Roots are divergent