1. Primary Dentition Review

2. Development and Eruption
All 20 primaries begin calcifying 4-6 months in utero (2nd trimester)
Crown completion in all primaries within first year after birth
Eruption occurs from 6 months to 2 years
Mixed dentition from age 6 to 12
Age 4-5 yrs, primate spaces develop due to growth of maxilla and mandible

3. Eruption Sequence
Mandibular teeth erupt prior to their maxillary counterparts
Sequence:
Centrals
Laterals
1st molars
Canines
2nd molars

4. Exfoliation sequence:
Preceeds the eruption sequence of the permanent dentition.
Root resorption begins one year prior to exfoliation
All primary second molars are lost about the same time

5. Unique Characteristics of Primary Teeth

6. All Primary Anterior Teeth...
Apical 1/3 of root curves facially
Facial crown surface smooth, no mamelons or perikymata
CE line on lingual is more apical than facial
Root is long relative to crown length
Incisal edge is in-line or just facial to mid-root axis

7. Primary Incisors... Maxillary central only incisor where M-D > I-C
Cingula of maxillary incisors are large (extending 1/3 of I-C length)
Mandibular central is symmetrical, incisal edge horizontally straight

8. Primary Maxillary Canine...
M-D width = I-C length*
Mesial HOC more cervical than distal HOC (similar to mandibular 1st premolar)
Mesial cusp ridge longer than distal cusp ridge (similar to maxillary 1st premolar)
Longest primary root

9. Primary Mandibular Canine...
Longest root of mandibular primary teeth
Cusp tip in-line with mid-root axis
No “moon-shape” curvature

10. General Characteristics of All Primary Molars
Primary firsts smaller than seconds
Occlusal tables are narrower F-L
Root furcations nearer to CEJ with little/no root trunks
Roots are slender and widely spread

11. Primary Maxillary 1st Molar
Resembles maxillary premolar
4 cusps: MB and ML larger than DB and DL (sometimes absent)
3 fossae/pits: mesial, central, distal
Grooves form an “H” pattern

12. More maxillary 1st... Transverse ridge connects MB & ML cusps
Pronounced MB cervical prominence
Facial bifurcation closest to CEJ compared to any other molars*

13. Primary Maxillary 2nd Molar
Resembles permanent 1st molar
Greatest root divergence of any primary molar
Distal root bifurcation most apical of primary molars*

14. Primary Mandibular 1st Molar
Doesn’t resemble any other tooth
Large MB cusp covering 2/3 of facial surface
Pronounced transverse ridge between MB and ML cusps
Four cusps: MB, ML, DB, DL
Occlusal table narrowest of molars; distal half wider F-L than mesial half*

15. More mandibular 1st... Prominent MB cervical prominence
Mesial marginal ridge overdeveloped, resembling small cusp
Mesial root apex is flat, almost square (unique)
Mesial HOC more cervical than distal
Mesial outline straight

16. Primary Mandibular 2nd Molar
Most closely resembles permanent mandibular 1st molar
All 3 buccal cusps more similar in size

17. All the Best on Your Exams