Dental pulp
Dr. Fatma Elturki
Objectives
 Definition
of the dental pulp.
 Development of the pulp.
 Anatomy of the pulp.
 Histology of the pulp.
 Functions of dental pulp.
 Age changes of dental pulp.
 Clinical considerations.
Dental pulp
 It
is
loose
delicate
connective tissue.
 It occupying the cavity
lying in the center of
dentin.
 It is confined within the
pulp chamber and root
canals of the tooth.
Pulp development
The pulp derived from
ectomesenchymal cells
of dental papilla.
During
dentinogenesis,
when the dentin forms
around
the
dental
papilla, the innermost
tissue is considered pulp.
Anatomy of the pulp
Apical foramen:
 The root canal terminate at
the apical foramen, where
the pulp and PDL meet and
the main nerves and vessels
enter and leave the tooth.
 In the developing tooth the
apical foramen is large and
centrally located.
 As the tooth completes its
development, the apical
foramen become smaller in
diameter
and
more
eccentric in position.
Anatomy of the pulp
Accessory or lateral canals:
 Connections
between the
pulp and PDL may also occur
along the lateral surface of
the root through accessory
canals.
Histology of the pulp




The odontoblastic Zone: On the
periphery of the pulp, adjacent
to the calcified dentin, Next to
the predentin lies the palisade
of columnar odontoblast cells.
The cell-free zone (zone of
Weil):
beneath
the
odontoblasts in the coronal
pulp.
cell-rich zone: where cell
density is high.
Pulp core: The main body of
the pulp occupies the area
circumscribed
by
cell-rich
zones. It contains the principal
support
system
for
the
peripheral pulp, which includes
the large vessels and nerves.
Structural Elements

Cells: which includes:
1.
2.
3.





Synthetic
cells
(fibroblasts,
odontoblasts).
Defensive cells (Dendritic
cells , macrophages, Tlymphocytes, etc).
Progenitor
cells
(undifferentiated
mesenchymal cells).
Fibers.
Ground substances.
Blood supply.
Lymphatics.
Nerve supply.
Synthetic cells
1- Fibroblasts




Fibroblasts
are
the
most
abundant cell population of
the pulp tissue.
They synthesize and secrete the
bulk
of
the
extracellular
components, that is collagen
and ground substance.
In addition to synthesis
of
collagen, they also eliminate
excess collagen or participate
in collagen turnover in the pulp
by resorption of collagen fibers.
In young pulp, the fibroblasts
appear large with multiple
processes, centrally placed
nucleus,
with
all
protein
synthesis organelles. By age, the
cell become smaller spindle
shaped with few organelles.
Synthetic cells
2-Odontoblast
 Odontoblasts
are the
largest group of
cells in the pulp.
 It is the principal cell
of the dentin forming
layer
 It is located around
the pulp chamber as
a single cell layer. But
only their cell bodies
are located lining the
outer pulpal surface
and their process
extend in the DT in
dentin.
2nd
Defensive cells
Histocytes and Macrophages: These
cells
are
highly
phagocytic and can remove
bacteria,
foreign
bodies
(endodontic paste, zinc oxide,
etc), dead cells, or other
debris.
Defensive cells
Polymorphonuclear Leukocytes: The
most common form of
leukocyte in pulpal inflammation
is
the
neutrophil,
although
eosinophils and basophils are
occasionally detected.
 It is important to know that
although neutrophils are not
normally present in intact healthy
pulps, with injury and cell death
they rapidly migrate into the areas
from nearby capillaries and
venules.
Defensive cells
Pericytes or endothelial
cells: They located around
blood vessels. The
function of these cells
is controversial, but
they are though to
be contractile cell
capable of reducing
the size of the vessel
lumen.
 It may differentiate
into odontoblasts.
Defensive cells
Lymphocytes and Plasma Cells: These inflammatory cell types
generally
appear
following
invasion into the area of injury
by neutrophils.
 These cells are not normally
present in healthy pulp tissue but
are associated with injury.
 Their presence would therefore
indicate the presence of a
persistent irritant.
Defensive cells
Mast Cells: These cells are seldom in
large numbers in normal,
healthy pulps but are
commonly
found
in
inflamed pulps.
 The granules of these
cells contain histamine,
and heparin.
 These cells release these
granules
into
the
surrounding tissue fluid
during inflammation and
they are generally found
near blood vessels.
Defensive cells
Dendritic cells: Bone marrow-derived,
antigen
presenting
dendritic cells.
 They
stimulate
the
division and activity of
T-lymphocyte.
 Found in and around
the odontoblast cell
layer.
Progenitor cells
Undifferentiated
Ectomesenchymal cells: It is embryonic branched cell
& can be differentiated into
other types of connective
tissue cells.
 It is smaller than fibroblasts but
have similar appearance.
 They are usually found along
the walls through out the cell
rich zone and pulp core.
 With age they decrease in
number.
Structural Elements
Extracellular: The dental pulp has most
of its volume primarily
composed of fibers and
ground substance.

These form the body and
integrity of the pulp
organ.
Extracellular
Fibers: These fibers form a
loose,
reticular
network to support
other
structural
elements of the pulp.
 The
fibers
are
principally type I and
type III collagen .
Extracellular
ground substance : This structureless mass, gellike in consistency, makes
up the bulk of the pulp
organ.
 It resembles the ground
substance
of
any
connective tissue .
 Composed
mainly
by
combinations
of
Glycosaminoglycans,
glycoproteins and water.
Supportive Elements
Pulpal Blood Supply : 


The pulp is highly vascularized,
with vessels arising from the
external carotids to superior and
inferior alveolar arteries and
drains by the same veins.
Capillary density is highest in the
subodontoblastic region with
loops
passing
between
odontoblasts
In
the
subodontoblastic region,
capillaries
with
fenestrations
occur frequently and regularly in
both primary and permanent
teeth.
Supportive Elements
Lymphatics:
Lymphatic vessels have been
identified in the pulp at the
ultra structural and histologic
levels by the absence of red
blood cells in their Lumina,
and the absence of a basal
lamina.
Supportive Elements
Nerves: Several nerve bundles, each
containing
numerous
unmyelinated and myelinated
nerves, pass into each root via
the apical foramen.


The myelinated nerve fibers
branch extensively beneath
the cell-rich zone to form the
so-called
plexus
of
Raschkow.
many fibers lose their myelin
sheath and pass through the
cell-free zone to terminate as
receptors or as free nerve
endings near odontoblasts.
Functions of dental pulp
1. Formative.
formation of dentin by odontoblast cells during
the developmental period.
2. Nutritive.
the high blood supply of the dental pulp transfer
the nutrients to the tooth.
3. Sensory.
the complex sensory system within the dental
pulp controls the blood flow and is responsible
for at least mediation of the sensation of pain.
4. Defensive.
formation of reparative or secondary dentin
represents a defensive response to any form of
irritation.
Age changes of dental pulp
1- The most conspicuous
changes is decreasing
volume of the pulp
chamber and root canal
due
to
continuous
dentin deposition.
Age changes of
dental pulp
2- With increasing age the
pulp
tissue
shows
a
reduction in the number of
the
cellular
elements
specially progenitor cells,
leading to reduction in
regenerative potential of the
pulp.
Young
pulp
Old
pulp
Age changes of dental pulp
3- The collagen fibers
increase in number
and density which
becomes
more
evident
with
the
decrease in pulp size,
so it produce an
actual fibrosis.
Age changes of dental pulp
4- with age, there is both loss and
degeneration
of
myelinated
and
unmyelinated nerve fibers that correlated
with age- related reduction in sensitivity.
Photomicrograph of control group after six months showing nerves plexus
under the odontoblastic zone and nerve bundle in the center of the pulp core
(Silver stain, origin. Mag. ×100)
Photomicrograph of control group after 12 months
showing nerve bundles in root canals (silver stain,
origin. Mag.×400).
Age changes of dental pulp
5- Calcification (pulp stones) is
a common age changes of the
pulp that may be occurs as
localized
or
diffuse
pulp
calcification.
Pulp stones or denticles are
nodular,
calcified
masses
appearing in either both the
coronal and root portions of
the pulp. They are usually
symptomless
unless
they
impinge on nerves or blood
vessels.
True pulp stones
False pulp stones
Diffuse calcifications


Diffuse
calcification
appear as irregular
calcific deposits in
the pulp tissue, usually
following collagenous
fiber bundles or blood
vessels.
Diffuse calcifications
are usually found in
the root canal and
less often in the
coronal area.
Clinical considerations
1- With advancing age,
there is a difficulty in the
endodontic treatment due
to:



Excessive
dentin
formation at the roof and
floor
of
the
pulp
chamber.
Presence of pulp stones
at the opening of the
root canal.
The apical foramen is
narrowed by cementum.
Clinical considerations
2when
accessory
canals are located near
the coronal part of the
root or in the bifurcation
area,
a
deep
periodontal pocket may
cause
pulp
inflammation.
Conversely a necrotic
pulp
can
cause
periodontal disease.
Clinical considerations
3- A non vital tooth
become brittle and is
subjected
to
fracture.
Therefore,
every
precaution
should
be
taken to preserve the
vitality of the pulp.
Clinical considerations
4- some materials such
as calcium hydroxide
seem
to
facilitate
dentin
bridge
formation. So, they
applied in deep cavity
preparation when the
dentin layer is very thin.