The dental pulp is loose connective tissue located within the tooth. It can be divided into the coronal pulp within the crown and radicular pulp within the root. The pulp contains cellular elements like odontoblasts, fibroblasts, and defensive cells, as well as neurovascular elements. With age, the size of the pulp decreases as secondary dentin is deposited. The number of cells and vascularity also decrease with age. Accessory canals may form due to developmental processes or resorption of tissue during aging. The pulp provides nutrients and defenses to the tooth.

1. Dr. Hesham
Dameer

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

4. Regions of the pulp cavity
• The pulp cavity can
be divided into two
main regions: the
coronal pulp is
located within the
crown of the tooth
and the radicular
pulp is located
within the root.
A, Coronal pulp; B, Radicular pulp

5. Morphlogy
*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.
*Apical foramen: The the periapical
tissue through the apical foramen.
The average size of the apical pulp
organs are continuous with
foramen of the maxillary teeth in
the adult is 0.4 mm, while in the
mandibular teeth it is 0.3 mm in
diameter.

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

7. Mechanism of accessory canals formation:
Mechanism of accessory canals formation:
1- it occurs in areas, where the developing root
encounters a large blood vessel, where dentin
will be formed around it, then making the lateral
canal .
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.

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

9. odontogenic
zone

10. Dentin
Odontoblasts layer
Predentin
Cell rich zone
Pulp core
Cell free zone

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

12. 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.

13. Histological Structures of the Pulp
The dental pulp is formed of specialize loose connective tissue
contain :
1) Cellular elements :
a. Formative cells : Odontoblast, Fibroblast .
b. Progenitor cells : Undifferentiated mesenchymal cells .
c. Defensive cells : Macrophages, neutrophils, eosinophils,
basophils, mast cells , plasma cells and Lymphocytes.

14. 2) Fibrillar elements :
a. collagen bundles
b. fine collagen fiber
3) Ground substance: Act as a medium to
transport nutrients to cells and metabolites of the
cell to the blood vessels.
4) Neurovascular elements : Blood vessels,
nerves, lymph vessels

15. 1- Formative cells :
a- odontoblasts:
5-7u in the diameter
25-40u in length.
In the early stage of development odontoblasts
consist of a single layer of columnar cells .
In the later stages of development, the
odontoblastic layer appeared pyriform where
the broadest part of the cell contains the
nucleus
They are longer in the crown and then become
cuboidal rootwise, at the root apex, they may
be almost flattened.

16. The cell membranes of adjacent odontoblasts
exhibit junctional complexes.
Gap junction
desmosome

17. b- Fibroblasts
These are the most numerous
type of cells.
They are spindle in shape.
They have elongated
processes which are widely
separated and 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.

18. These cells have a dual function: synthesize and
degradation of fibers and ground substances in the
same cell .
mitochondria
In young pulp, they are :
*large cells *with large
multiple processes
*centrally located oval
nucleus, Fibroblast
(protein secreting cell).
*numerous mitochondria,
*well developed Golgi
bodies
*well developed RER

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

20. 2- Defensive cells:
A- Histiocyte ( macrophage ) :
In light microscope, the cells appear
irregular in shape with short blunt
processes.
The nucleus is small, more rounded and
darker in staining than fibroblast.
Their presence is disclosed by intra-vital
dyes such trypan blue.
These cells are distrbuted around the
odontoblasts and small blood vessels
and capillaries.

21. In case of inflammation,
*nuclei, increase in size and
exhibit a prominent nucleolus.
it exhibits granules and
vacuoles in their cytoplasm
Invaginations of plasma
membrane are noted
ultastructurally with
aggregation of vesicles or
phagosomes .

22. b- Plasma cells:
These cells are seen during
inflammation.
The arrangement of chromatin gives
the nucleus a cart wheel
appearance.
The mature type exhibits a typical
small eccentric nucleus and more
abundant cytoplasm.
The plasma cells are known to
produce antibodies.

23. c- Lymphocytes
They are found in normal
pulp and they increase
during inflammation.

24. c- Eosinophils
They are found in
normal pulp and they
increase during
inflammation.

25. d- 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 histamin &
heparin.

26. 3- Progenitor cells:
(The undifferentiated mesenchymal
cells):
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 connective tissue cells.

27. Fibers of the pulp
In young pulp the fibers are
relatively sparse and delicate
throughout the pulp and gradually
the bundles increase in size with
advancing age.
In older pulp two patterns of
collagen distribution can be seen:
one is a diffuse collagen network
with no definite orientation,
the second is bundles of collagen.
There are no elastic fibers in the
pulp except those present in the
walls of the larger blood vessels.

28. 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

29. Vascularity and Nerves of the Pulp
 The pulp organ is extensively vascular with vessels arising from
the external carotids to the superior or inferior alveolar arteries. It
drain by the same vein.
 Blood flow is more rapid in the pulp than in most area of the body,
and the blood pressure is quite high.
 The walls of the pulpal vessels become very thin as their enter the
pulp.
 Nerves : Several large nerves enter the apical canal of each Molar
and Premolar and single ones enter the anterior teeth. This trunks
transverse the radicular pulp, proceed to the coronal area and
branch peripherally.

30. • Structure of Tooth
A - crown
B - enamel
C - dentine
D - gum
E - tooth pulp
F - cement
H - nerves & blood
vessels

32. Nerve Plexus of Raschkow
• Sensory nerve fibers that originate from
inferior and superior alveolar nerves
innervate the odontoblastic layer of the
pulp cavity. These nerves enter the tooth
through the apical foramen as myelinated
nerve bundles. They branch to form the
subodontoblastic nerve plexus of
Raschkow which is separated from the
odontoblasts by a cell-free zone of Weil. In
addition to the sensory nerves,
sympathetic nerve bundles also enter the
tooth to innervate blood vessels.

33. A, Odontoblasts; B, Cell-free zone of Weil; C, Nerve plexus of Raschkow

34. Nerves in pulp

35. Dental Pulp
Nerve Blood vessel

36. Vascular supply of pulp cavity
• The pulp cavity receives blood from
one artery that enters the apical
foramen and courses directly to the
coronal pulp. Within the coronal pulp
numerous arterial branches form a
interconnected network of blood
vessels. The smallest capillary loops
are in the subodontoblastic zone.

37. Clinically Importance features of the Dental Pulp
 With age the pulp becomes less cellular. The number of
cells in the dental pulp decreases as cell death occurs with
age.
 The volume of the pulp chamber with continued deposition
of secondary dentine. In older teeth, the pulp chamber
decreases in size; in some cases the pulp chamber can be
obliterated. An increase in calcification in the pulp occurs
with age.
 An increase in calcification in the pulp occurs with age.

38. Age changes in the pulp
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.

39. Retrogressive and age changes :
1) Cellular changes : during the time of teeth development the pulps of the teeth
are highly cellular , extensively vascular, and the cells show high mitotic rate .
Further more the fibroblasts and odontoblasts are actively synthesizing cells ,
while the ground substance is found in a profuse amount.
However, in aged pulp, the cells become decreased in number and the cell
organelles ( endoplasmic reticulum, Golgi and mitochondria ) also reduced in
number and size .The fibroblasts appear round with short processes and
termed fibrocytes . The odontoblasts enter their quiescent stage and their
activity becomes restricted .
2) Fibrosis : by aging, the pulp shows accumulation of diffuse fibrillar
components especially in the coronal part .
3) Neurovascular changes : with aging the blood vessels as will as the nerves
undergo reduction in number and size . the blood vessels undergo
arteriosclerosis, resulting in diminished blood supply to the pulp cells .The
degenerative changes of the vessel wall include the three layers of the
vessels . The nerves undergo progressive mineralization of the nerve sheath
or the nerve itself .
4) Reduction in pulp size : this occur due to continuous deposition of secondary
dentin through the life span of the tooth , and may eventually leads to pulp
obliteration .
5) Dystrophic calcification and pulp denticles :

40. Pulp calcification
localized
diffuse
(pulp stones )
True denticle False denticle

41. 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.

42. False denticles
*They are evidence of dystrophic
calcification of the pulp tissue .
*They contain no dentinal tubules.
*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.

43. *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.
*The close proximity of pulp stones free
to blood vessels may cause
atrophy of it.

44. 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.

45. Free True
Denticle

47. Odontoblast
Dentinal
Tubules
Predentin

48. A, True pulp stone; B, Pulp
cavity; C, Dentin

49. A, False pulp stone; B, Pulp cavity
False pulp stone

50. Functions of the pulp
Functions of the pulp
1- Inductive:
Dental papilla induces the enamel organ
formation and also determines the
morphology of the tooth .
2- Formative :
Pulp organ produces dentin. Odontoblasts
develop the organic matrix and function in its
calcification.

51. 3-Reparative: through the formation of highly
mineralized reparative dentin at the site of
injury to seal off the pulp from the source of
irritation . Also the pulp may mineralize the
affected dentinal tubules by forming
sclerotic dentin .
4-Defensive : pulp inflammation represents
other aspect of its response to irritation. In
this condition, the defensive cells of the
pulp
will be increased and activated to repair
and heal the inflamed pulp and
phagocytoses the invading bacteria and
their toxin .

52. 5- Protective: : any environmental irritating
stimuli always elicit pain as a response .
6- Nutritive : the extensive pulp vasculature
ensures an excellent nourishment to the
odontoblasts for the continuously forming
secondary dentin . This is provided through the
capillaries found in the odontogenic zone .

54. Dr. Hesham
Dameer