276
UNIT 3
Organ Systems
T. Yangi
Odontoblasts
Predentin
Dentin
Cell-free
Cell-free
zone
zone
Cell-free
zone
Cell-rich
zone
Pulp core
Blood
vessel
Apical foramen
Apical foramen
Apical foramen
Radicular
Radicular
pulp
pulp
Radicular
pulp
Coronal
Coronal
pulp
pulp
Coronal
pulp
Blood vessels
Blood vessels
and nerves
and nerves
Blood vessels
and nerves
A
Figure 14-17A.
Dental pulp
. H&E,
3
136
Dental pulp
is a specialized loose, cellular mucous
connective
tissue that f
lls the pulp chamber in the central core and
root canals oF the tooth. ±ibroblasts are the most numer-
ous cells in the pulp; they produce connective tissue f
bers
(mainly type I and III collagen, f
bronectin, and elastin)
and ground substance. They maintain the pulp matrix. The
second most numerous cells are
odontoblasts
( producing
dentin). Other deFense cells, such as
macrophages
and
lymphocytes
, may be Found in the pulp.
No mast cells
or
adipocytes (fat cells)
are Found in the pulp. The pulp con-
tains many blood vessels and nerve f
bers, which enter and
leave at the apical Foramen. Most oF the nerve f
bers are
aFFerent f
bers; they are either C f bers or A
d
f
bers, and
both carry pain inFormation through the trigeminal system
to the brain. The eFFerent f
bers are autonomic nerve f
bers
and innervate the smooth muscle oF the blood vessels.
Dental pulp plays an important role in producing dentin
and providing nutrients and sensory input For the dentin.
Dental pulp
Predentin
3. Cell-rich zone
1. Odontoblast
layer
2. Cell-free zone
(zone of Weil)
Odontoblasts
Cell-free
zone
Dentin
Dentinal
tubules
B
Figure 14-17B.
Dental pulp
. H&E,
3
136; inset
3
190
Dental pulp
is derived From mesenchymal tissue that Forms
the dental papilla during tooth development. The papilla
becomes pulp in the mature tooth. The pulp can be divided
into Four zones From the periphery to the center. (1) The
odontoblast layer
Forms a single cell layer along the periph-
eral edge oF the pulp. These cells have processes extending
into the dentin. (2) The
cell-free zone
, also called the
zone
of Weil
, is directly under the odontoblast layer. This layer
has f
bers, cellular processes, axons, and capillaries running
through it but contains no cell nuclei. (3) The
cell-rich zone
is beneath the cell-Free zone, and has many cells and nuclei
oF cells densely packed in rows. This layer has f
broblasts,
undiFFerentiated mesenchymal cells, neural plexuses, and
capillaries. IF some odontoblasts die, the undiFFerentiated
mesenchymal cells in this layer will diFFerentiate into new
odontoblasts. (4) The
pulp proper (pulp core)
is the cen-
tral part oF the pulp and contains blood vessels and nerves
within the loose, mucous connective tissue. The layers oF
both cell-Free and cell-rich zones are more visible in the
coronal
than the
radicular pulp
region (±ig. 14-17A).
CLINICAL CORRELATION
Figure 14-17C.
Pulp Abscess.
H&E
3
23; inset
3
168
Pulp abscess
reFers to an abscess involving the pulp tissue oF a tooth.
Pulp abscesses are usually sequelae oF dental caries, but they can also
develop in teeth showing no detectable lesions. Pulp abscesses can also
occur aFter restoration work has been perFormed. They are characterized
by severe, intermittent pain that may intensiFy when a patient reclines.
Sharp pain may also be triggered by cold liquids, tapering oFF to a dull,
pulsating pain. Periapical tissues may not be involved, and the aFFected
tooth may not show any diFFerence From other healthy teeth in percussion
or pressure tests. Treatment includes using antibiotics and
undergoing
root canals and even tooth extraction.
Pulp cavity
Abscess with
neutrophils
C
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