1. The Pulp
Dr Jamal Naim
PhD in Orthodontics

2. The Pulp
It is a specialized loose connective tissue occupying a cavity in the dentine. It is a remnant of the embryologic organ for tooth development.
It has an ectomesenchymal origin.

3. The Pulp
At first the pulp is called dental papilla; which is highly vascular; and its cells develop into fibroblasts and odontoblasts.
After dentin formation this tissue is called dental pulp.
dental papilla

4. Both dentin and pulp have a common origin from the dental papilla.

5. Anatomy of Pulp
Pulp horns or cornua
Pulp Chamber or coronal pulp, located in the crown of the tooth.
Root canal or radicular pulp, is the portion of the pulp located in the root area.
The apical foramen is the opening from the pulp at the apex of the tooth to be continuous with the periapical tissue .
Accessory canals or lateral canal, extra canal located on the lateral portions of the root.

6. The coronal pulp
It is called pulp chamber, where in young teeth it is large and have the shape of the D.E.J.
The pulp chamber has pulp horn (s) according to the number of the cusps.
Pulp horns

7. The radicular pulp
In anterior teeth it is single, in posterior teeth it is multiple.
Its shape conforms to the D.C.J.
Apically the root canal opens to the periodontal ligament by apical foramen.
Pulp horns
Root canals

8. The apical foramen
The pulp organs are continuous with the periapical tissue through the apical foramen.
The average size of the apical foramen is:
maxillary teeth: 0,4 mm
mandibular teeth: 0,3 mm
apical foramen

9. The apical foramen
As the root begins to develop, the apical foramen is actually larger than the pulp chamber, but it becomes more constricted at the completion of root formation.

10. Accessory canals
Acc. canal
The pulp cavity is sometimes connected with the periodontal tissue with an opening rather than the apical foramen, the lateral, accessory or supplementary canal.
pulp
PDL

11. Accessory canals
They are numerous in the apical third of the root and in the bifurcation of multirooted teeth.
If the root canal breaks up into multiple tiny canals, it is referred to as a delta system because of its complexity.

12. Accessory canals

13. Etiology of accessory canals
Degeneration of the epithelial root sheath of Hertwig before odontoblasts differentiation.
Large blood vessel disturbs the course of the root sheath.
Lack of union of the tongue like projection (in multi-rooted teeth).

14. Histology of the pulp tissue

15. Microscopic Zones in Pulp
(peripheral zone)
(Weil zone)
(central zone)

16. Microscopic Zones in Pulp
(peripheral zone)
(Weil zone)
(central zone)

17. Predentin Odontoblasts Cell-free zone Cell-rich zone Odontoblastic
process
Predentin
Cell bodies
Odontoblasts
Cell-free zone
Cell-rich zone

18. Odontoblastic layer
Dentin

20. Odontoblastic layer Adjacent to predentin
Odontoblast bodies (perikaryon) in the pulp and processes (tomes fibre) in dentin.
Odontoblastic layer

21. Odontoblastic layer
Tomes process
Cell body

22. Cell free zone (Weil zone)
Dentin

23. Cell free zone (Weil zone)
It is about 40 micron thick.
It is prominent in the coronal pulp and less prominent in the radicular pulp.
Cell free zone
It contains few cells.
In the zone many processes of the fibroblasts of the cell rich zone, nerves and blood vessels are observed.

24. Cell free zone (Weil zone)
Odobtoblasts
Blood vessel
Nerves

25. Cell rich zone
Dentin

26. Cell rich zone
It is present between the cell free zone and the pulpal core
It is composed of:
Fibroblasts,
undifferentiated mesenchymal cells
extensive vascular system
Cell rich zone

27. Cell rich zone
Odobtoblasts
Fibroblasts
Nerves

28. Pulpal core
Dentin

29. Cross-section from the central pulp showing major support systems, including arterioles (A) with a muscular wall, thin-walled lymphatics (L), venules (V), and nerve bundles (NB)

31. Cells of the pulp Progenitor cells (UMC) Synthetic cells Odontoblasts
Fibroblasts
Defensive cells
Histocytes
Lymphocytes
Mast cells
Plasma cells

32. Progenitor cells (UMC)
They are also called Reserve Cells.
They are descendants of undifferentiated cells in the primitive dental papilla.
They are multipotential cells and likely a fibroblast type.
They are found along the blood vessels
They retain the capability of
dedifferentiating on demand into
many of the mature cell types.

33. Odontoblasts tomes fiber predentin
They line the pulpal surface of dentin
A layer of predentin is always present between them and dentin.
Each odontoblast has a cell body (perikaryon) and a protoplasmic process (tomes fiber)
tomes fiber
predentin
perikaryon

34. Odontoblasts The odontoblasts are arranged in a single layer where:
In the pulp chamber the cells are crowded and appear psudostratefied columnar.
Near the beginning of the root canal they become columnar in shape.

35. Odontoblasts
In the mid portion of the root canal they become cuboidal in shape.
In the apical area of the root canal they become flat cells.

36. Fibroblasts They are star like cells with ovoid nucleus.
The greatest number in the dental pulp, particularly in the cell rich zone.
Their function is to form and maintain the pulp matrix.
They also eliminate excess collagen

37. Defensive cells Histocytes and macrophages :
Large oval or spindle shaped
The cytoplasm is granular, especially during inflammation
Have large lysosomes
Main function is to eliminate
dead cells.

38. Defensive cells Lymphocytes and plasma cells:
These cells are not normally present in healthy pulp tissue but are associated with injury and resultant immune responses attempts to destroy, damage, or neutralize foreign substance.
These inflammatory cell types generally appear following invasion into the area of injury.

39. Defensive cells
Their presence would therefore indicate the presence of a persistent irritant.
plasma cells
Lymphocyte

40. Defensive cells Plasma cells produce antibodies.
The nucleus is eccentric with cart wheel appearance.
plasma cell

41. Defensive cells Mast cells:
Mast cells are seldom in large numbers in normal, healthy pulps, but are commonly found in inflamed pulps.
Have granular cytoplasm with round nucleus.

42. Defensive cells
The granules of these cells contain histamine, a potent inflammatory mediator, and heparin.
These cells release these granules or degranulate into the surrounding tissue fluid during inflammation.

43. Matrix and ground substance
The extracellular compartment (matrix) is a structureless mass, gel-like in consistency and consists of collagen fibers and ground substance.
The ground substances resembles that of other loose connective tissue.
It consists of acid mucopolysaccharides, neutral glycoprotein and water.
It acts as a medium for the transport of nutrients.

44. Matrix and ground substance
These fibers form a loose, reticular network to support other structural elements of the pulp.
Collagen is synthesized and secreted by odontoblasts and fibroblasts.
However, the type of collagen secreted by odontoblasts to subsequently mineralize differs from the collagen produced by pulpal fibroblasts, which normally does not calcify.

45. Matrix and ground substance
The collagen fibers are particularly type I and type III collagen.
In young pulps there are single fibers scattered between the cells. As age change the pulp become fibrilar.
The greatest concentration of collagen fibers occurs in the most apical portion of the pulp.

46. Matrix and ground substance
The bundles of collagen at the pulp periphery are termed von Korff’s fibers.
They are corkscrew-like and originating between odontoblasts to pass into the dentin matrix.