Asalaam Alekum
1/03/2015
Histology & physiology of
the Pulp
Dr. Gaurav Garg, Lecturer
College of Dentistry, Al Zulfi
Majmaah University
Learning Objectives
• At the end of lecture students should
know:
• Definition, location, development & parts of
•
•
dental pulp
Composition, structure & different nerve fibers
of dental pulp & their functions
Functions, age changes & pathophysiology of
dental pulp
DENTAL PULP
Definition :- Dental pulp is a connective
tissue uniquely situated within the rigid
encasement of mineralized dentin.
DENTAL PULP
 Pulp is the formative
organ of the tooth.
 It occupies the centre
of each tooth.
 Consists of soft
connective tissue.
DENTAL PULP
•Its development starts at
about the 6th week of
intrauterine life during the
initiation of tooth
development.
• Dental papilla differentiates to form pulp.
DENTAL PULP
Pulp organ consist of two parts :• Coronal pulp - located
centrally in the tooth
• Radicular pulp- located in
•
root.
It extends from cervical region
of crown to the apex and is
continuous with periapical
connective Tissues through
apical foramen and accessory
canals.
Composition of dental pulp
CELLS OF DENTAL PULP
• Odontoblasts
• Preodontoblasts
• Fibroblasts (predominant cells)
• Undifferentiated mesenchymal cells (Reserve
cells)
• Cells of immune system:
Macrophages, T-Lymphocytes, Histiocytes,
Dendritic cells
Other Components
•Fibers – Type I and III collagen
•Intercellular ground Substance –
Glycosaminoglycans, glycoprotein's and water
•Blood vessels
•Lymph vessels
•Nerves
Pulp calcifications
Pulp stones or denticles:
 Free Stones:- Which are
surrounded by pulp tissue
 Attached Stones:- Which are
continuous with dentin
 Embedded stones:- Surrounded
completely by dentin.
Diffuse calcifications
Structure of pulp
 Central region of pulp contains
large nerve trunks and blood
vessels.

Peripherally ,the pulp is
circumscribed by the specialized
odontogenic region composed
of
– Odontoblasts
– Cell free zone (Weil’s zone)
– Cell rich zone
Structure of pulp
D- dentin, P- predentin, O- odontoblasts, CF- cell free zone, CR- cell rich zone,
CP- central pulp
Structure of pulp
Pain/ nerve fibers in pulp
A-delta fibers
(D=1-6µm)
 Myelinated
 In odontoblastic &
subodon. zone
(peripherally)
 Fast (2-30)m/sec
 Carry initial sharp
momentary pain
C fibers
(D=0.4-1.2µm)
Unmyelinated
Central portion of
pulp tissue
Slow(0.4-2)m/sec
continuous or
throbbing pain
A-delta fibers
 Can be stimulated
without injuring the
tissue.
 Low excitability
threshold
 Respond to electric
vitality tests
C-fibers
associated with
tissue injury and
inflammation.
High
Do not
A-delta fibers
 Response to cold
sensitivity tests is
positive.
 Immediate & first
response to heat
C-fibers
Negative
Delayed and
Prolonged
Other nerve fibers
• A- beta fibers (1-5%) (6-12µm) – More
fast conducting, touch or pressure
sensitive.
Functions of Pulp
 Inductive- induces formation of dentin
 Formative- forms dentin throughout life
 Nutritive- nutrition of the dentin is a function of the
odontoblast cells and the underlying blood vessels
 Protective- protect itself by formation of dentin
 Defensive- due to presence of defense cells
 Sensation- due to presence of nerves
Pulp changes with age
• Pulp volume decreases by forming additional
•
•
•
•
calcified tissues on the walls
Number of cells decreases and the fibrous
component increases
Decrease in the number of blood vessels and
nerves
Calcification of arterioles and precapillaries
Decreased ability to recover from injury.
Pulpal Pathophysiology
Irritation to clinical crown (tooth preparation, caries)
Release of
inflammatory mediators
( 5-HT, Histamine, PG’s)
Release of
neuropeptides
Localized pulpal inflammation
(Hyper-excitation, vasodilatation, vascular
leakage)
Increased local tissue pressure
Increased local tissue pressure
Venous collapse
Stasis/decrease blood flow
Release of inflammatory agents
Local necrosis
Vascular disturbances
Increased tissue pressure
Necrosis of tissue
Total Pulpitis
Franklin S Weine; endoodontic therapy,5th edition
ischemia
References
• Pathways of pulp; Stephen Cohen
• Endodontics; Franklin S. Weine
• Textbook of Endodontics; Ingle & Bakland