The document provides information on the structure and functions of the dental pulp. It begins with definitions and general anatomy, describing the pulp as a soft connective tissue enclosed within dentin. It then discusses the zones and structural features of the pulp in more detail. This includes the odontoblastic zone containing odontoblasts and nerve endings, the cell-free zone with capillaries and nerves, and the cell-rich zone with fibroblasts and blood vessels. Key cell types like odontoblasts, fibroblasts, and immune cells are also described. The functions of the pulp in dentin formation, nutrition, and defense are highlighted.

1. PULP
Dr. Meera K Pynadath
Department of oral pathology and microbiology
Royal dental college

3. Contents
• Introduction
• General anatomy
• Functions
• Structure of pulp

4. INTRODUCTION
Definition:
“A richly vascularized and innervated connective tissue of mesodermal
origin enclosed by dentin with communications to the periodontal
ligament.”
The term ‘ pulp’ is derived from Latin word “pulpa” – animal or plant
tissue which is moist or soft occurring in the form of cohesive mass.

5. GENERAL ANATOMY
• Occupies centre of tooth – pulp
chamber & root canals
• Soft connective tissue
• Crown – coronal pulp
• Root – radicular pulp
• Total volume
• All permanent teeth pulp – 0.38 cc
• MV – single tooth – 0.02 cc
• Molar pulp 3 -4 times larger than
Incisor pulp

6. Coronal pulp
• In young tooth resemble outer
surface of coronal dentin.
• 6 surfaces
• Occlusal or roof
• Mesial
• Distal
• Buccal
• Lingual
• Floor
• Pulp horns – no of cusps
• Pulpal constriction by dentin
deposition esp at floor

7. Radicular pulp
• From cervical region to root apex
• Single to multiple
• Tubular shape due to dentinal wall tapering
• Continuous with periapical connective tissues through apical foramen
• During the root formation the apical end is a wide opening limited by
epithelial diaphragm
• Apical pulp canal becomes smaller with cementum deposition

9. Apical foramen
• Av size – 0.4mm – 0.3 mm
• Location & size of apical foramen alters due to functional influences
• Periapical tissue exerts pressure on apical foramen – resorption
• At same time cementum is laid down in the opposite side – shifting
of foramen
• More lateral position
• Or 2 foramina separated by dentin & or cementum

10. Accessory canals
• Canals from radicular pulp laterally through root dentin to
periodontal tissues
• More in apical 3rd region
• Clinically significant – spread of infection
• Unknown origin
• But could be due to loss of HERS cells in these areas which have to
form dentin OR
• Due to presence of blood vessel, dentin is formed around to develop
the canal

12. FUNCTIONS
• INDUCTIVE
• FORMATIVE
• NUTRITIVE
• PROTECTIVE
• DEFENSIVE OR REPARATIVE
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13. INDUCTIVE
Primary role – interact with oral ectoderm to form DL & EO
Also interact with enamel organ to decide the particular tooth type.
FORMATIVE
Pulp organ cells – odontoblast – dentin – protect pulp
NUTRITIVE
Nourishes the dentin through odontoblasts & their processes by
vascular supply
PROTECTIVE
Sensory nerves respond to noxious stimuli with pain. Nerves also
initiate reflexes (sympathetic function) that control circulation of
pulp
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14. • DEFENSIVE OR REPARATIVE
• Reparative abilities – regenerative dentin or reparative dentin
• Sclerosis
• Pulpal inflammation
• Macrophages, lymphocytes, plasma cells, monoytes & mast cells
• Hyperemia and edema
• Fluid accumulation
• Increased pressure on apical vessels
• Ischemia & necrosis
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15. STRUCTURAL FEATURES OF PULP
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16. CONTENTS OF PULP
1. Intercellular substance
2. Fibroblasts
3. Fibers
4. Undifferentiated mesenchymal cells
5. Odontoblasts
6. Defense cells
7. Pulp stem cells
8. Blood vessels
9. Lymph vessels
10. Nerves
11. Nerve endings
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17. Zones of pulp
• Peripheral region of pulp is circumscribed by specialized odontogenic
region composed of:
Zones of pulp Description
The odontoblastic zone
-
Lines the outer pulp wall and consist of cell bodies of
odontoblasts which form secondary dentin thereby
causing cell bodies to realign themselves. Cell bodies
of afferent axons located b/w odontoblast bodies.
Cell free zone (zone of
Weil)
Relatively accelular, accommodate odontoblasts
during development and function of teeth. Nerve and
capillary plexus are located here.
cell rich zone Contains increased density of cells comprising
principally of fibroblasts and undifferentiated
mesenchymal cells. Also contain extensive vascular
supply.
Pulp core The main body of pulp; contains principal support
system for peripheral pulp including large vessels &
nerves from which branches out to supply outer pulp
layers. Also contain fibroblasts, ground substance
and collagen.

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19. Odontoblastic zone
• Comprises of cell bodies of odontoblasts, capillaries, unmyelinated
sensory nerves and dentritic cells.
• Odontoblasts (5 marks)
• Second most prominent cells in the pulp
• Specialised, end cells (non dividing), produce dentin
• Arranged in a single layer (monolayer) near predentin
• The cells appear to be multilayer (peudostratified)-> artefact
 Crowding of odontoblasts
 Tangential plane sections
• Cell bodies lie in pulp and odontoblastic process in dentinal tubule.
• Cell bodies are arranged in “palisading pattern”
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21. • The capillary network passes among odontoblasts .
• The terminal capillaries loops are located among the odontoblasts .
• They have fenestrations in the endothelial cells .
• These pores are involved in the rapid transport of metabolites at the
time of dentinogenesis.
• Unmyelinated sensory nerves terminate among or pass between
odontoblasts to enter into dentinal tubules.
• The nerve terminals contain round or oval enlargements
• They are terminal filaments that contain microvesicles , small dark
granular bodies and mitochondria.
• They are located very close to the odontoblast plasma membrane
• Act as sensory receptors to pain.
• The sensory response in pulp cannot differentiate between heat, touch,
pressure or chemicals.
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22. Cell free zone (zone of weil)
• Relatively acellular zone, located central to odontoblastic zone
• Contains capillary plexus, plexus of Raschkow and ground
substances
• Also contains some fibroblasts, undifferentiated mesenchymal
cells and macrophages
• Fibroblasts produce reticular fibers
• If odontoblasts are destroyed , new ones are formed from
undifferentiated mesenchymal cells
• Macrophages -> phagocytosis
• This layer is inconspicous during rapid dentinogenesis.
• Capillary plexus – nutrition of odontoblasts and cells of this zone and
is clearly visible only in the period of dentinogenesis and inflammation
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23. • Plexus of Raschkow / parietal layer of nerves/
subodontoblastic plexus of Raschkow
• The peripheral axons of nerves forms a network in this zone
• Both myelinated axons , ranging from 2-5 µm in diameter and minute non
myelinated fibres approx 200 – 1600 µm in size make up this layer
• This layer is primarily located in the roof and lateral walls of coronal
pulp and less developed in root canal.
• The parietal layer develops gradually becoming prominent when root
formation is complete , thus plexus is established after tooth eruption.
• From the plexus the fibers extend as a unmyelinated form towards the
odontoblasts where they lose their myelin sheath.
• The fibers terminate as free nerve endings near odontoblasts and extend
between them or further up to dentinal tubules.
• They function transmitting pain stimuli from heat, cold, or pressure.
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24. Cell rich zone
• This zone is located central to the cell free zone
• Comprises of –
▫ fibroblasts,
▫ undifferentiated mesenchymal cells,
▫ collagen,
▫ ground substances
▫ macrophages.
▫ Extensive vascular supply
▫ and nerve supply
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25. Pulp core
• Central zone
• Pulp proper
• Comprises of
▫ Fibroblasts
▫ Collagen
▫ Blood vessels
▫ Nerves
▫ Ground substances.
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27. INTERCELLULAR SUBSTANCES
• Ground substances which are dense & gel like nature varies in
nature from finely granular to fibrillar
1. Glycosaminoglycans –
1. Chondroitin A & B -
2. Hyaluronan – mechanical function and cell migration
2. Proteoglycans –
1. versican, - form bulk of proteoglycan
2. syndecan - act as a adhesion molecule between fibroblast and collagen
3. Glycoproteins –
1. Integrins – cell surface adhesion receptors
2. tenascin -
3. fibronectin - cell adhesion and cell migration
4. laminin – basement membrane of b.v. and and coats odontoblastic
cell membrane.

28. FIBROBLASTS
• Most predominant cell type of the pulp
• Origin – undifferentiated mesenchymal cells & dividing fibroblasts
• Secretion – collagen formation and ground substance
• Location – numerous in cell rich zone ,ie, central part of coronal
pulp
• Structure of an active fibroblast - Typical stellate shape
• extensive processes that link other fibroblasts and odontoblasts by
intercellular junctions – “Arms of stars linking”
• Deeply stained nuclei & lighter cytoplasm
• EM – RER, mtc & others

29. • In young pulp cells divide & are active in protein synthesis
• Older pulp – spindle shape, short process & fewer organelles
• - fibrocytes
• Function :
1. Forms pulp matrix – collagen bundles and ground substances,
even can form calcified tissue, also can replace dead odontoblast –
reparative dentine formation
2. degradation of matrix (dual function)
3. inflammation – secrete colony stimulating factor that attract
inflammatory cells and secrete inflammatory mediators
4. healing – secrete angiogenic factors like FGF2 and VEGF
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32. FIBERS
Mainly collagen fibers
Type I – 60% and type III – 40 %
They have a 64nm cross striations but differ from type III having only
alpha 1 chain and type I – alpha 1 and alpha 2 chains.
Collagen fibrils of 10 – 100 nm diameter grouped into fibres thinly and
and irregularly scattered through out tissue
Near predentin – they are more organised they have a parallel
arrangement
Fibrillin – a large glycoprotei that form non collagenous beaded
microfibril – 10 -12 nm diameter
Pulp is devoid of elastic fibers
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34. • Down regulation and deregulation of fibrillin -> release of
transforming growth factor – beta (TGF – β)
• As the pulp ages the collagen fiber content increases
• Compared to coronal third the apical third is more fibrous -> to
protect neurovascular bundles.
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35. UNDIFFERENTIATED MESENCHYMAL CELLS
• Derived from mesenchymal cells of dental papilla
• Primary cells in young pulp but very few remain after root
completion
• Structure :
• Appear larger than fibroblasts and are polyhedral shape
• Peripheral processes & large nuclei
• Lack RER
• Found along pulp vessels, in the cell rich zone & scattered through out
the central pulp
• Pleuripotent nature – odontoblast, fibroblasts, osteoclast etc
• Decreases with aging
• Repair and regeneration
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37. ODONTOBLASTS
• Second most prominent cells.
• Lies in odontogenic zone of pulp near predentin.
• Specialised, end cells (non dividing), produce dentin
• Arranged in a single layer (monolayer) near predentin
• The cells appear to be multilayer (peudostratified)-> artefact
 Crowding of odontoblasts
 Tangential plane sections
• Cell bodies lie in pulp and odontoblastic process in dentinal tubule.
• Cell bodies are arranged in “palisading pattern”
• No of odontoblasts = no of dentinal tubule s
• 59000 to 76000/mm2 in coronal dentin with lesser number in root dentin.
• Origin - cells are derived from dental papilla -> undifferentiated
mesenchymal cells -> pre odontoblast -> odontoblast .
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38. Structure
• Contains cell body and odontoblastic process
1. Cell body - 5-7 µm in diameter and 25 – 40 in length
• Odontoblastic bodies are not arranged uniformly on pulp.
• More tall columnar near crown, more cuboidal near root & spindle shape
near apex.
• Basally placed nucleus
• RER, GA, Mt, cytoplasm is devoid of organelles near pulp dentin
junctions
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39. 2. odontoblast processes/ Tome’s fibre
• Cell graduallly narrow down as it enters predentine about 3- 4 µm
• Cytoplasmic extension of odontoblasts
• These process extend through dentinal tubule
• Show largest diameter near pulp & tapers to outer dentin
• Disagreement on the extend of processes
• Tubulin throughout the thickness of dentin
• Some are shortened- tubules either narrow or obliterated
• Contain:
• Microtubules, intermediate filaments,- in linear pattern , very few or nil organelles,
and dense granules, micro vesicles
• Extension & branching : Enamel spindle
• Terminal branch & lateral branching
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40. • Function
• Odontoblasts produce dentin,
• release inflammation mediators,
• regulate vasodilation & BP
• cell proliferation
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41. DEFENCE CELLS
• Histiocytes or tissue macrophages
• Dentritic cells
• Mast cells
• Plasma cells
• Vascular elements – neutrophils, eosinophils, basophils,
lymphocytes & monocytes
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42. HISTIOCYTES OR MACROPHAGES
• Irregular shaped cell with
short blunt processes
• Smaller & more rounded
nucleus
• Granular cytoplasm
• Associated with small BV
• Active inflammatory cell
• Contain phagosomes
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43. DENTRITIC CELL
• Close in relation to endothelial
cells
• Express macrophage related
antigens
• Antigen presenting cell to T
lymphocytes
• In deciduous cells lies close
relation to odontoblasts
• Number increases in areas
with DC, attrition etc
• Immunosurveilance
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44. LYMPHOCYTES & EOSINOPHILS
• Found extravascularly
• Increase in number during
inflammation
• T types predominate
• Mast cells are also seen –
round nucleus contain dark
stained granules
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45. PLASMA CELLS
• During inflammation of pulp
• Small & concentric nucleus
• Chromatin is adherent to
nuclear membrane –
cartwheel appearance
• Basophilic cytoplasm
• mature cells – eccentric
nucleus & abundant cytoplasm
• Produce antibodies
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46. Thank You
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