The dental pulp is a soft connective tissue located within the tooth. It develops from the dental papilla during tooth formation. The pulp has four zones - the odontoblastic zone containing cells that form dentin, the cell-free zone, cell-rich zone containing many cells, and a central zone with large blood vessels and nerves. The pulp receives blood vessels through the apical foramen and contains many cell types including odontoblasts, fibroblasts, immune cells, and undifferentiated cells. It is highly innervated with sensory fibers that detect pain and sympathetic fibers that control blood flow. The pulp plays key roles in tooth development, defense against infection, and sensitivity.

1. THE PULP
“THE PULP IS A SMALL TISSUE WITH A BIG
ISSUE” – I.B BENDER
Dr.Mohan Kumar Subramaniam, Post graduate,Dept of Conservative dentistry & Endodontics

2. OVERVIEW
 DEFINITION
 DEVELOPMENT
 STRUCTURE AND COMPONENTS
 VASCULATURE
 INNERVATION
 METABOLISM
 FUNCTIONS
 AGE CHANGES
 SIGNIFICANCE

3. The pulp is a soft connective tissue of mesenchymal origin
residing within the pulp chamber and root canal of teeth
(Cohen).

4. The Development
•
During the 8th week of IUL, there is condensation of the
mesenchmye under the enamel organ-Dental papilla.
•
The enamel organ enlarge and enclose the dental papilla
in their central portion.
•
Dental papilla controls the morphology & type of tooth
to be formed.
•
Dental papilla shows :
a.
extensive proliferation of cells
b.
High vascularity

5. The Development
 Capillaries crowd around the odontoblast during active dentinogenesis

Rim of the enamel organ (IEE & OEE) is the cervicalloop.

Root formation is carried out by the proliferation of cells at the cervical loop.

6. CORONAL PULP

It is the pulp occupying the pulp chamber of the crown of the tooth

In young teeth it resembles the shape of the outer dentin

It has six surfaces : occlusal, mesial, distal, buccal, lingual and floor.

Pulp horns are projections into the cusp
 This pulp constricts at the cervical region where it continues as the radicular
pulp

7. RADICULAR PULP

It is the pulp occupying the pulp canals of the r oot of the tooth.

In the anterior teeth it is single and in the posterior teeth it is multiple

The radicular portions of the pulp is continuous with the periapical tissues
through apical foramen

As age advances the width of the radicular pulp is reduced, and so is the apical
foramen.

8. APICAL FORAMEN

Pulp cavity terminates at root apex as small opening called apical foramen

Radicular pulp continuous with connective tissue of the periodontium through
this foramen.

Diameter in an adult- maxillary teeth-0.4mm mandibular teeth-0.3mm
 Wide open during development of root

9. ACCESSORY CANAL
 Leads laterally from the radicular pulp into the periodontal tissue.

Presents in the apical third of the root sheath cells
 Formed due to premature loss of HERS or when
developing root encounters a blood vessel.

Overall occurrence is 33%

May also be present at the furcation region

10. PULP DENTIN COMPLEX
The intimate
relationship between
the odontoblasts, cells
present at the pulp
surface which are
responsible for dentin
formation and the
dentin can be refered
to as the PulpoDentin
Complex.

11. HISTOLOGY
When the pulp is examined microscopically four distinct zones can be
distinguished.
o
The odontogenic zone composed of odontoblasts (at the periphery).
o
The cell free zone or Weil’s zone.
o
The cell rich zone.
o
The central region or zone containing large nerves and blood vessels.
HISTOLOGY

13. THE ODONTOBLASTIC ZONE

14. CELL FREE ZONE
 It is also called weil’s zone

40 microns wide & relatively free of cells, Traversed by
1. blood vessels
2. unmyelinated nerves
3. cytoplasmic process of fibroblasts

This zone is found below the odontoblastic zone

Represents the space into which odontoblasts move during tooth development.

15. CELL RICH ZONE
•
subodontoblastic layer
•
Contains
more
proportions
of
fibroblast
and
undifferentiated mesenchyml cells.
•
Also contains macrophages, dendritic cells and
lymphocytes.
•
Formed due to migration of cells from pulp proper
•
Mitosis seen when dead odontoblasts are replaced
•
Also contain young collagen fibres during early
dentinogenis.

16. PULP CORE
•
The central connective tissue mass from the cell rich
zone inward
•
It contains blood vessels and nerves embedded in the
pulp matrix together with fibroblasts.
•
In young pulps, the cell population is greater while in
older pulps fibre density is higher.
•
The neurovascular bundles enter / exit this core
through the apical foramen

17. CELLS OF PULP
 ODONTOBLASTS
 FIBROBLASTS
 UNDIFFERENTIATED CELLS
 DEFENSE CELLS

18. ODONTOBLASTS

Arranged in Palisading pattern.

Shape may vary,
cornal pulp- columnar
Midportion - cuboidal
Apical region–Flattened
•
These cells have large process extending into dentin
•
The no of odontoblasts corresponds to the number of dentinal tubules
•
Average no of odontoblasts estimated to 45,000 per Sq.mm of
odontogenic zone.

19. Odontoblast process
 The odontoblast process is a direct extension of
the cell body and occupies most of the space
within the dentinal tubules
•
Its diameter is 3 to 4 um at the pulp-predentin border
•
Mainly composed of protein-tubulin, actin and vimentin
Cavity or crown preparation may disturb odontoblast
processes, leading t0 irreversibly damage d
odontoblasts(Odontoblast Aspiration)

20. %
TERTIARY
REPARATIVE
REACTIONARY
PULP

21. Functions of Odontoblast
 Synthesis of organic matrix
 Synthesis of non collagenous substances like
sialoprotein, phosphophoryn, osteocalcin ostenoectin & osteopontin
 Intracellular accumulation of calcium
 Degradation of organic matrix
•
Study shows that OB form first line of defence against cariogenic
bacteria
• Secretion of the pre-Dentin matrix occurs adjacent to the cellular
front.
•
They can help in apexigenesis, i.e formation of radicular apex with
dentin

22. FIBROBLAST
 Cells that occur in greatest number in the pulp

Function is to form, maintain the matrix that consists of collagens, fiber and ground
substance throughout the pulp
 Numerous in the coronal portion of the pulp, where they form the cell-rich zone.
 In Young teeth , Fibroblasts have abudant cytoplasm having numerous cell
organcells

Apoptopic cell death of pulpal fibroblasts, especially in the
cell-rich zone, indicates cell turn over
 It has capability of ingesting and degrading the organic
matrix.

23. UNDIFFERENTIATED MESENCHYME
 These mesenchymal cells are distributed through
out the pulp, frequently around the perivascular
area - believed to be toti potent cell
 They are Polyhedral shaped with peripheral
processes and large oval nuclei
 Difficult to differentiate from fibroblast under light microscopy
 Under adequate stimilus they may differentiate into odontoblast , fibroblast or
macrophages.
 In older pulps, the number ofundifferentiated mesenchymal cells may
diminish,which may also reduce the regenerative potential of the pulp

24. IMMUNOCOMPETENT CELLS
The ability of connective tissue to generate and support local inflammatory
and immune reactions makes it an active participant in host defense.
 These cells are recruited from blood stream and remain as transient inhabitants in
pulp
They are
1. Macrophages
2. Mast cells
3. Plasma cells
4. Lympocytes,Neutrophils,Eosinophils
basophils and monocytes.

25. MACROPHAGES IN PULP
 Described as histiocytes (or) as resting wandering cells
 Located close to blood vessel
 Have several phenotypes
 Macrophages are phagocytes, function of which are engulfment and digestion
of the foreign material
 During inflammation they appear in large number to aid in defense of the
organism
 In all they constitute 8-9% of the pulpal cell population
Dark staining nucleus with cytoplasmic
granules

26. PLASMA CELLS
 Plasma cells are seen during inflammation of the
pulp
 The plasma cells function in the production of
antibodies.
 Plasma cells may be present in coronal pulp
 They have small nuclei with radiating chromatin
that appears like a cast wheel
Peripheral arrangement of chromatin in
nucleus

27. MAST CELLS
 Occur in small groups in relation to blood vessels
 Present only during pulpal inflammation
 Have round nucleus and contain many dark staining
granules in the cytoplasm.
 Their number increase during inflammation

28. LYMPHOCYTES
 The composition of lymphocytes in the pulp resembles that seen in other
connective tissues.
 These cells are scattered predominantly along the blood vessels in the pulp
proper, although numerically fewer among pulpal cellular elements.

29. •
COLLAGEN
•
ELASTIN
•
FIBRONECTIN
•
LAMILIN
GAG
PR OTEOGLYCAN

30. COLLAGEN FIBRES
 Extra cellular structural protein,major constituent of connective tissue
 Collagen fibers appear through out the pulp
 Young fine fibers ranging in diameter from 10-12mm.
 Pulp collagen fibers do not contribute to dentin matrixproduction
.
 After root completion pulp matures and bundles of collagen fibers increase in
number
 They scattered throughout the coronal or radicular
pulp,or they appear in bundles.These are termed diffuse or bundle collagen

31. COLLAGEN FIBRES
 Main types of collagen present are Type I and Type III
 Type I – responsible for pulpal & core architecture, secreted by fibroblasts. Ca
– 56%
 Type III – backbone for vessels, nerves in the central pulp; mainly distributed
in cell rich, and acellular zones
Ca – 41%
 Type V and Type VI collagen form a mesh on the stroma of the pulpal
connective Tissue.
 Type IV and VI is a component of the basal membrane of the pulpal capillaries

32. GROUND SUBSTANCE
 It is a structureless mass,makes up the bulk of the pulp.
 Consists of complexes of proteins,carbohydrate and water.
 Broadly classified as
 Glycoaminoglycans
 Proteoglycans

33. GROUND SUBSTANCE
 GAG found in pulp is mainly chondroitin sulphate, dermatan sulphate &
hyaluronic acid
 Proteoglycans occupy larger area and they provide protection against
compression.
 During dentinogenesis,the ground substance show affinity for collagen and
influence fibrinogenesis.
 They have capacity to bind with calcium and help in mineralisation.

34. FUNCTIONS OF PULPAL EXTRACELLULAR
MATRIX
• Maintain tissue’s physical properties and
integrity
• Control of growth and development and repairs
• Control of cell migration
• Control of diffusion of macromolecules
•
Nanci A. Dentin-Pulp Complex. In: Ten Cate's Oral Histology: Development, Structure, and Function. St.
Louis: Mosby, 2003.
•
Garant PR. Oral Cells and Tissues. Chicago:Quintessence, 2003.
34

35. PULPAL VASCULATURE

36. PULPAL VASCULATURE
 The pulp organ is extensively vascularized.
 They are supplied by the superior and the inferior alveolar arteries
 The blood vessels gain entry into the pulp through the apical foramen and at
times through accessory foramen
APICAL THIRD
MIDDLE THIRD

37. PULPAL VASCULATURE
 The arterioles on entering the pulp shows a reduction in thickness of vessel wall
musculature and therefore luman size increases.

Pulpal blood flow is more rapid than in most other area of the body
 The flow of blood in
Arterioles - 0.3 to 1mm/sec
Venules – 0.15mm/sec
Capilaries – 0.08mm/sec

38. PULPAL VASCULATURE

39. Organization of Pulp Vasculature
 Pulp is a micro circulatory system which lacks true arteries and veins.
 The largest vessels are arterioles & venules which regulate the local interstitial
environment.
ARTERIOLES
(50μ DIAMETER)
TERMINAL ARTERIOLES
PRECAPILLARIES
METARTERIOLES
CAPILLARIES (8μ)

40. CAPILLARIES
 Function as exchange vessels regulating the transport of diffusion of substances
between blood and local interstitial tissue elements

They consists of single layer of endothelium surrounded by basement
membrance

Capillary pressure –35 mmHg

Capillary wall is 0.5μ thick & acts as semipermeable
membrane
 Fenestrated capillaries & Continuous capillaries
(non fenestrated) are the types present in the dental pulp.

41. LYMPHATICS
• They start as blind openings near Weil’s zone &
odontoblastic layer
• The larger lymphatic vessels run along the blood
vessels & nerves
• Multiple collecting lymph vessels exit though the apical foramen & drain
lymph from pulp into the periodontium
• They transport lymph to the regional lymph node before it enters into
the blood vessels. This provides an immuno surveillance function.

42. METABOLISM
 Metabolism has been studied by measuring the rate of O2 consumption.
 During dentinogenesis, rate of O2 consumption is high than after crown
completion.
 Greatest metabolic activity is seen in the odontoblast layer.
 Reduced pH of pulp causes decreases in O2 consumption as seen in pulp
abscess.
 In addition to the glycolytic pathway, the pulp has the ability to produce energy
through Pentose shunt pathway, suggesting that the pulp can function under
varying degrees of ischemia.

43. INNERVATION
• Dental pulp contains sensory and motor fibers to
fulfill the vasomotor and defense function
• Sensory afferent fibers are branches of
maxillary & mandibular
division of trigeminal nerve.
• After entering the foramen, they arborize. Larger fibers are present in
the central zone. They divide as they proceed peripherally and coronally.
• Subjacent to the cell rich zone, the nerves branch extensively forming a
parietal layer of nerves- NERVE PLEXUS OF RASHKOW. This layer
contains both A and C fibers.

44. INNERVATION
 Above the cell free zone, myelinated fibers begin to lose their myelin sheath.
 In the cell free zone, they form a rich network responsible for pain.
 Nerve endings may also enter the dentinal tubules
incidence - 10-20% in cusp tips
1% at the level of CEJ
 Motor nerves are supplied by the sympathetic division of autonomic nervous
system.
 They wrap around the arteries and terminate in the tunica media.
 They control the diameter of the vascular lumen & therefore blood flow &
volume & ultimately the intrapulpal pressure.

45. A-beta fibers




C fibers
Conduction velocity 30-70 m/s
Very low threshold, nonnoxious sensation
40% of myelinated fibers in
pulp
Functions not fully known






A-delta fibers
 Conduction velocity -
m/s
 Lower threshold
 Involved in fast, sharp pain
Non-myelinated
sympathetic fibers


 Stimulated by hydrodynamic
stimuli
 Sensitive to ischemia
 Sharp pain
Conduction velocity - m/s
Higher threshold
Involved in slow, dull pain
Stimulated by direct pulp
damage
Sensitive to anesthetics
Dull pain

Conduction velocity 0-2 m/s
Post-ganglionic fibers of superior
cervical ganglion
Vasoconstriction & Vasodilation.

46. INNERVATION
Nerve ending patterns
Penetration
Dentin
into
Plexus of Rashkow
46

47. FUNCTIONS OF DENTAL PULP
 INDUCTIVE
 FORMATIVE
 NUTRITIVE
 PROTECTIVE
 DEFENSE

48. INDUCTIVE

Induce oral epithelial differentiation into dental lamina and enamel organ
formation.
 Also induces developing enamel organ to become a particular type of tooth.

49. FORMATIVE

Produces the dentin that surrounds and protects the pulp.

Odontoblasts develop the organic matrix and function in its calcification.

The cells also determine the form acquired by the coronal pulp chamber as
well as volume of the pulp.
Lisi S, Peterkova R et al: Tooth Morphogenesis and pattern of odontoblast
diff, Conn Tiss Res 44(sppl 1) 167, 2003.

50. NUTRITIVE
NUTRITIVE
- Dentin being avascular, depends on the underlying pulp for blood
& drainage.
- Nourishing the dentin through the odontoblasts and their
processes and the blood vascular system of the pulp.
Lijima T, Zhang J: Three dimensional wall structure and innervation of dental pulp. Microsc Res Tech 56:32,2002
Kramer IRH, The vascular architecture of the human pulp, Arch Oral Bio 2:177, 1960

51. PROTECTIVE
 Pulp helps in recognition of stimuli like heat ,cold, pressure & chemicals by
way of sensory nerve fibres.
 Vasomotor innervation controls the muscular wall of blood vessels.This
regulates the blood volume and rate of blood flow and hence the intrapulpal
pressure.
Haug SR, Heyeraas KJ: Modulation of the dental inflammation by the sympathetic nervous system, J Dent Res 85: 488495, 2006

52. DEFENSE
 Pulp has remarkable reparative abilities,
  It responds to irritation by producing reparative dentin
  Mild to moderate irritation results in continued
peritubular dentin
formation, sclerosis and intratubular calcifiction-(Tublar sclerosis).
 Various cells of the pulp aid in the repair process. The rigid dentinal wall and
the unyielding, enclosure can lead to partial or complete vascular collapse and
necrosis of the pulp.
 However, if the inflammation is not too severe, the pulp will heal via its
excellent regenerative properties.
Kim S: Neurovasclar interactions in the dental pulp in inflammation, J Endod 16: 48-53, 1990

53. DECIDIOUS PULP
 Overall dimensions smaller.
 Pulp chambers larger.
 Roots are long and slender and root canals narrower and follow a
tortuous course.
 Pulp horns at a higher level, especially mesial horns of primary
molars.
 Resorption starts soon after root completion.
 Root resorption and dentin deposition changes size
shape and number of root canals.

54. REGRESSIVE CHANGES (AGING)
 Appearance of fewer cells in aging pulp.

Cells are characterized by a decrease in size and no of cytoplasmic organelles.

Active
pulpal
fibrocyte
(or) fibroblast
has
abundant
rough-surfaced
endoplasmic reticulum , notable golgi complex & numerous mitochondria.
 Fibroblast exhibit less perinuclear cytoplasm, long thin cytoplasmic processes.

Intra cellular organelles are reduced in number and size.

55. FIBROSIS
Diffuse fibrillar components
 Accumulation of both
Bundles of collagen fibres

Fiber bundles may appear arranged longitudinally in the radicular pulp and more
diffused in coronal pulp.
 Increase in fibers in the pulp organ is gradual and generalized.
 External trauma such as dental caries (or) deep restorations cause a
localized fibrosis (or) scarring effect.
 Increase in collagen fibers decrease s the size of the pulp.
 Atherosclerotic plaques may appear in pulpal vessels.

56. PULP STONES
 Pulp stone or denticles are nodular, calcified masses appearing in either or both
in coronal and root portion of the pulp organ in teeth.

Asymptomatic unless they impinge on nerves (or) blood vessels.

Seen in functional as well as embedded unerupted teeth.
CLASSIFICATION
True
denticles
False
denticles
Diffused
calcifications
Goga, R.; N. P. Chandler & A. O. Oginni (2008). "Pulp stones: a review". International Endodontic Journal 41: 457–468.

57. TRUE DENTICLES
 True denticles are similar in structure of dentin.
 They have dental tubules and contain processes of the odontoblasts
 Usually located close to the apical foramen.
 Development of true denticles is caused by the inclusion of remnants of the
epithelial root sheath with in the pulp

Epithelial remnants induce the cells of pulp to differentiate into
odontoblasts then form the dentinmass.

58. FALSE DENTICLES
 They do not exhibit dentinal tubules.
 They appear as concentric layers of calcified tissue.
 These calcification sites appear within a bundle of collagen fibers or they
appear in pulp free of collagen accumulations.
 Center of these concentric layers of calcified tissues there may be remnants of
necrotic and calcified cells

Calcification of thrombi in blood vessels called phleholiths, may also serve as
nidi for false denticles
False calcification seen along the walls of the blood vessel

59. DIFFUSE CALCIFICATIONS
 Appear as irregular calcific deposits in the pulp
tissue, following
collagenous fiber bundles and blood vessels.

Sometimes they develop into larger mass, persist as calcified spicules.
 These calcifications are usually found in the root canal and less often in coronal
area.

60. DYSTROPHIC MINERALIZATION
 Ground substance alterations in the dental pulps
occurs on aging, such
changes may contribute to cellular degeneration and
increase
dystrophic
mineralization.
 Circulatory disturbances
may be the initiating factor.
 Mineralizations also seen in the myelin sheaths of nerves.
 Older, fibrotic pulp attract mineral salts more readily.
 DM also increase as result of disease processes such as caries and periodontal
diseases
 Teeth whose pulps one chronically inflammed
previous liquefaction necrosis.
contain DM in regions of

61. EFFECT OF PULP ON CAVITY PREPARATION
 Frictonal Heat: In historical handpieces – heavy torque, low rpm and steel burs
Caused scorching of pulp
 Remaning Dentin Thickness of 1 mm protects pulp thermally as Dentin is an
effective insulator
 ‘Boiling away’ of tubular fluid leads to dessication by the heat produced. Which
leads to Intense sensitivity
 ‘Blushing’ of dentin – hemorrhage due to frictional heat.
 Solution: Bur-dentin interface wetness & finishing with hand instruments
-Murray PE, Lumley J, Smith AJ: Preserving the vital pulp in operative dentistry: 3. Thickness of remaining cavity
dentin as a key mediator of pulpal injury: Jent Update 29 (4): 172, 2002
-Mullaney TP, Laswell HR: Iatrogenic blushing of dentin. J Prosth Dent 22(3):354, 1989

62. CAVITY DEPTH

1mm – Shields Pulp

0.5- 0.25mm – Tertiary Reactive Dentin

0.25mm> ~ Odontoblasts die & Reperative dentin is formed
very fast.

63. CAVITY DRYING
Strong capillary forces
Outward flow of Dentinal
fluid/Odontoblast displacement
This is replaced by fluid from
the pulp
Stimulates Nociceptors
Produces Pain

64. Other effects
 Follow the same response pattern as mentioned above
 Generally seen in –

Etching Dentin

Smear Layer Removal

Polishing Restorations ( 20° approx in amalgam)

Post Restorative Sensitivity (Microleakage of toxins & cytotoxic materials
from restoration)


-Camps J, Dejou J, Remesat M et al, Factors influencing pulpal response to cavity restorations. Dent Mater
16(6): 432, 2000
-Grajower R, Kaufman E, Rajstein J; Temp in the pulp chamber during polishing of restorations, J Dent Res
53(5): 1189, 1974

65. STEM CELLS OF PULP
 Hematapoietic Stem Cells (HSC)
 Mesenchymal Stem Cells (MSC)
 Embryonic Stem Cells