1. Morphology of Primary Teeth
Dr Heba Mohd El khodary
Dr Heba Mohd El-Khodary

2. Objectives:
Identify and distinguish morphologic differences in primary teeth.
Apply the knowledge of morphology in clinical procedures for children
Dr Heba Mohd El-Khodary

3. Primary Dentition 20 primary teeth as compared to 32 permanent teeth
No premolars in the primary dentition
The primary molars are replaced by the premolars
The permanent molars erupt distal to the primary second molars
Dr Heba Mohd El-Khodary

4. General Morphologic considerations
Crown
Root
Pulp
Dr Heba Mohd El-Khodary

5. I- Size & Color
Smaller
MD width of ant. Primary < ant. Permanent teeth
MD width of Primary molars > Permanent premolars
Bluish-white (Primary) vs grayish-white or yellowish-white (Permanent) This has to be kept in mind during shade selection for composite restoration or crown restoration.
Dr Heba Mohd El-Khodary

6. II- Crown Crown form ( MD > OG ) anterior = cup posterior = square
This is important during the selection of the stainless steel crown.
Bulbous crown: Steep Cervical constriction /Prominent cervical bulge
[ G. floor – Matrix type ].
Care must be taken while preparing the proximal box, as there is risk of pulp exposure at the
site of constriction.
Class II cavity should be restored with proper placement of wedges at the constricted area so that the matrix band is adapted well to the tooth surface.
Narrow occlusal table: Convergence of buccal & lingual walls.
The width of he cavity should also be less in a deciduous tooth.
Dr Heba Mohd El-Khodary

7. Contact area in primary broader, flatter and more gingival:
[B&L wall of proximal box extend towards embrasure / gingival seat below contact area]
Primary
Dr Heba Mohd El-Khodary

8. Cervical
constriction
Square
Cup

9. II- Crown Thin Enamel Clinical significance: Early diagnosis of caries
Bur size (recommended bur is no 330 pear shaped )
Sufficient bulk of restoration
Care must be taken during cavity preparation, not to extend very deep as there is increased chance of pulp exposure.
Dr Heba Mohd El-Khodary

10. Enamel rods incline occlusally vs horizontal or apical in gingival 1/3
No beveling at the gingivo-cavo surface line angle is not required, as no enamel remain unsupported.
Dr Heba Mohd El-Khodary

11. III- Root Roots are longer & more slender.
Crown root ratio bigger in primary teeth.
Roots are narrower MD than those of permanent.
No root trunk in primary molars
Roots of primary molars are widely divergent to accommodate buds of permanent premolars : Extraction ?
Dr Heba Mohd El-Khodary

12. Roots are more Slender & longer
Crown/Root ratio
Dr Heba Mohd El-Khodary

13. No
Root
trunk
Widely
Divergent
roots
Dr Heba Mohd El-Khodary

14. IV- Pulp Follows the morphology of crown Higher pulp horns / mesial
Pulp chamber is larger in relation to crown size compared to permanent teeth / cavity depth
Canals of primary molars have many lateral branches and apical ramifications
Wide apical foramina
Increased blood supply : typical inflammatory response
Less nerve fibers : less sensitivity to pain
Dr Heba Mohd El-Khodary

15. Dr Heba Mohd El-Khodary

16. Summary Primary teeth have Thinner enamel and dentin layers
Pulp horns closer to the outer surface
Mesial pulp horn much higher
Relatively larger pulps
Enamel rods direct slightly occlusally in the cervical area
Cervical area is constricted significantly
Roots flare as they approach the apex
More tortuous and irregular pulp canals
Dr Heba Mohd El-Khodary

17. Dr Heba Mohd El-Khodary

18. Dr Heba Mohd El-Khodary

19. During Cavity Preparation: The depth of the cavity should be less.
The width of the cavity should also be less in a deciduous tooth.
Care must be taken while preparing the proximal box, as there is risk of pulp exposure at the site of constriction.
Care must be taken during cavity preparation, not to extend very deep as there is increased chance of pulp exposure.
Enamel beveling at the gingivocavo surface line angle is not required, as no enamel remain unsupported.
The proximal box preparation may have to be extended widely to break the contact free.
Dr Heba Mohd El-Khodary

20. Thank you
Dr Heba Mohd El-Khodary