The dental pulp is loose connective tissue located in the center of the tooth that contains blood vessels, nerves, and cells like odontoblasts. It has formative, nutritive, protective, and defensive functions. Over time, the pulp undergoes changes like decreased size and vascularity, increased calcification in the form of pulp stones or diffuse deposits, and reduced vitality.

3. The dental pulp is that loose
delicate connective tissue
occupying the cavity lying
in the center of dentin.

4. Morphology
*The coronal pulp: it is present in
the pulp chamber.
*The radicular pulp: it is that part
of the pulp extending from the
cervical region of the crown to the
root apex.

5. Accessory canals:
They are commonly seen to extend
from radicular pulp laterally
through the root dentin to the
periodontal ligament. Accessory
canals
They are numerous in the apical
third of the root.

6. Mechanism of formation accessory
canals
1- it occurs in areas, where the developing root
encounters a large blood vessel, where
dentin will be formed around it.
2- Early degeneration of the epithelial root
sheath of Hertwig before the differentiation of
the odontoblasts.
3-Lack of complete union of the epithelial
diaphragm at the floor of the pulp chamber.

7. *Apical foramen: The pulp organs are continuous
with the periapical tissue through the apical foramen.
The average size of the apical foramen:
maxillary teeth : 0.4 mm
mandibular teeth : 0.3mm

8. Pulp Exposure

9. Infected
pulp
Abcess

12. Dental pain (acute pulpitis)
Dental pain occurs in 12% of population.
The origin of the dental
pain is difficult to localize.
(referred pain)
Dental pain is the most unkilling acute pain
affecting human being.

13. Loss of the pulp
results in loss of the
pulp functions, but
the tooth is still
functioning

14. Histological structure of the
pulp
The dental pulp is formed of specialized loose
connective tissue:
cells fibers intercellular substances
blood vessels and nerves

15. Zones of the pulp
peripheral zone
Central zone
(odontogenic zone). (pulp core).
Dentin

16. Odontogenic zone:
a- odontoblasts:
Location: Adjacent to the predentin with
the cell bodies in the pulp and cell
processes in the dentinal tubules.
Dentin

17. B- Cell free zone (the zone of Weil):
*It is present beneath the odontoblastic layer.
*It is suggested to be the area of mobilization
and replacement of odontoblasts.
C- cell rich zone:
It is present beneath
the cell free zone.
It is composed of
fibroblasts and
undifferentiated
mesenchymal cells.

18. odontogenic
zone

19. Cell free zone & cell
rich zone might be
artifacts.

20. Cells of the pulp
1- Progenitor cells:
Undifferentiated mesenchymal cells.
2- Synthetic cells (formative cells):
Odontoblasts and fibroblasts.
3- Defensive cells:
Macrophages, lymphocytes, eosinophils,
mast cells and plasma cells.

21. 1- Progenitor cells:
(UMC):
They are smaller than fibroblasts
but have a similar appearance.
They are usually found along the
walls of blood vessels.
These cells have the potentiality
of forming other types of
formative or defensive cells.

22. 2-Formative cells:
A- Odontoblasts
Length: 25-40u
Diameter: 5-7u
In the early stages of development
odontoblasts consist of a single layer of
columnar cells .
In the later stages of development, the
odontoblasts appeared pyriform where
the broadest part of the cell contains the
nucleus

23. Odontoblasts are
longer in the crown
cuboidal rootwise,
flat at the root apex

24. The cell membranes of adjacent odontoblasts
exhibit junctional complexes.
The clear terminal part of the cell body and the
adjacent intercellular junction is known as
terminal bars.
Gap junction
desmosome

25. B- Fibroblasts
*These are the most numerous
type of pulp cells.
*They are spindle in shape.
*They have elongated processes which
are link up with those of other pulpal
fibroblasts (stellate appearance).
*The nucleus stains deep with
basic dye and the cytoplasm is
highly stained and homogenous.

27. These cells have a double function: formation and
degradation of fibers and ground substances.
mitochondria
In young pulp, they are :
*Large cells .
*With large multiple processes
*Centrally located oval nucleus,
*Numerous mitochondria, Fibroblast
*Well developed Golgi bodies
*Well developed RER
protein
secreting cell

28. In periods of less activity and aging they
appear smaller and round or spindle-shaped with
few organelles, they are termed fibrocytes.
fibroblast
fibrocyte

29. Infected pulp
L
L

30. 3- Defensive cells:
A- Histiocyte (macrophage):
They appear irregular in shape with
short blunt processes.
The nucleus is small, more rounded &
darker in staining than fibroblast.
They are distributed around the
odontoblasts and small blood vessels
and capillaries.

31. In case of inflammation:
*Nuclei increase in size and exhibit
a prominent nucleolus.
*It exhibits granules and vacuoles
in their cytoplasm.
Ultastructurally,
invaginations of plasma membrane
with aggregation of vesicles or
phagosomes .

32. *Macrophages are involved
in the elimination of dead
cells.
*Macrophages remove
bacteria and interact with
other inflammatory cells to
protect the pulp during
inflammation.

33. L

34. Phagocytosis
Hydrolytic
enzymes

35. B- Plasma cells:
These cells are seen during
inflammation.
The nucleus of this cell is small and
appears eccentric in the
cytoplasm.
The arrangement of chromatin in
the nucleus gives the cell a cart
wheel appearance,
The plasma cells are known to
produce antibodies.

36. C- Lymphocytes
They are found in normal
pulp and they increase
during inflammation.

37. D-Eosinophils
They are found in
normal pulp and they
increase during
inflammation.

38. E- Mast cells:
*They have a round nucleus and their
cytoplasm contains many granules.
*They are demonstrated by using
specific stains as toluidine blue.
*They produce histamine& heparin.

39. The ground substances of the pulp:
*The ground substances consists of acid
mucopolysaccharides and neutral glycoprotein.
*These substances are the environment that
promotes life of the cells.
*Glycoseaminoglycans are bulky molecules
and hydrophilic, they form gels that fill most of
the extracellular space, They contribute to the
high tissue fluid pressure of the pulp.

40. Blood vessels
*The pulp is highly vascularized. It is
supplied by the inferior and superior
alveolar arteries.
*As the vessels enter the tooth, their
walls become considerably thinner
than those surrounding the tooth.
D
*Along their course they give numerous
branches in the radicular pulp that
pass peripherally to form a plexus in
the odontogenic region.

41. The rate of blood flow in the pulp of the tooth is four
time the rate of blood flow in resting muscle.
Laser Doppler
Flowmetry
It measures the rate of
pulpal blood flow

42. The capillaries adjacent to the odontoblasts are
fenestrated. Such capillaries are found in areas
of rapid exchange.

43. Assessment of pulp vitality
Current pulp tests assess the function of
nerves in the pulp, by the application of electric
current or a rapid change in temperature.
Recently, blood flow rate in the pulp is used
to measure the degree of the pulp vitality.

44. Nerves of the pulp
The pulp has an abundant nerve supply
which follows the distribution of the
blood vessels.
Two types of nerve fibers are
present:
*Sympathetic in nature.
They control the contraction of the
smooth muscles of the blood vessels.
*Sensory nerves.
Both contain myelinated and
unmyelinated axons.

45. *As the mylelinated nerves run coronally, they give off
side branches and lose their myelin coat. They form
then sub-odontoblastic plexus of nerves known as
plexus of Rashkow. Few axons extend in-between the
odontoblasts to give the nerve endings.
*More nerve endings are found in the pulp horns than in
other peripheral areas of the coronal or radicular pulp.

46. Sensory response in the pulp cannot differentiate
between heat, touch, pressure or chemicals.
This is because the pulp organs lack those
types of receptors.
 Heat,
Pain
 Touch,
 Pressure,
 Chemicals

47. Functions of the pulp
1- Inductive:
Dental papilla induces the enamel organ
formation and also determines the
morphology of the tooth.

48. 2- Formative :
Pulp organ produces dentin. Odontoblasts
develop the organic matrix and function in its
calcification.

49. 3- Nutritive :
The pulp nourishes the dentin. Nutrition is
mediated through the odontoblasts and
their processes.
Dentin

50. 4- Protective:
The sensory nerves in the tooth respond with
pain to all stimuli, Pain sensation is a useful
alarm system of the pulp.

51. 5- Defensive or reparative:
The pulp responds to irritation by producing
reparative dentin and mineralizing any affected
dentinal tubules.
These reparative reactions are an attempt to
wall off the pulp from the source of irritation.
The presence of macrophages, lymphocytes and
leucocytes aid in the process of repair of the
pulp.

53. Age changes in the pulp
The size of the pulp
The apical foramen
The cellular elements decreased
The bl. vessels & n.
Vitality
Reticular atrophy: The total affect is the
production of a lessened vitality of the pulp
tissue and a lessened response to stimulation.

54. Pulp clacification
localized
diffuse
(pulp stones )
True denticle False denticle

55. True denticles
True denticles are rare &
small in size&
found near the apical foramen.
They consist of irregular dentin
containing traces of dentinal
tubules and few odontoblasts.
odontoblast
Remnants of the epithelial root dentinal
sheath invade the pulp tissues tubules
causing UMC of the pulp to form
this irregular type of dentin.

56. False denticles
*They are evidence of dystrophic
calcification of the pulp tissue .
*They contain no dentinal tubules and
can exist in any area of the pulp.
*They are formed of degenerated cells
or areas of hemorrhage which act as a
central nidus for calcification.
*Overdoses of vit. D, may favor the
formation of numerous denticles.

57. *Pulp stones are classified according
to their location into: free,
attached and embedded.
*They continue to increase in size
and in certain cases they fill up
the pulp chamber completely. attached
*If pulp stones come close enough
to a nerve bundle pain may be
elicited.
free
*The close proximity of pulp stones
to blood vessels may cause
atrophy of it.

58. Diffuse pulp calcification
*Commonly occurs on top of
hyaline degeneration in the
root canal and not common in
the pulp chamber.
*They are irregular calcific
deposition in the pulp tissue
following the course of blood
vessels or collagenous bundle.
*Advancing age favors their
development.