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Dental Pulp
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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
OVERVIEW
DEFINITION
DEVELOPMENT
STRUCTURE AND COMPONENTS
VASCULATURE
INNERVATION
METABOLISM
FUNCTIONS
AGE CHANGES
SIGNIFICANCE
The pulp is a soft connective tissue of mesenchymal origin residing within the pulp chamber and root canal of teeth
(Cohen).
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
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.
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
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.
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
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
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.
HISTOLOGY
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.
THE ODONTOBLASTIC ZONE
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.
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.
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
CELLS OF PULP
ODONTOBLASTS
FIBROBLASTS
UNDIFFERENTIATED CELLS
DEFENSE CELLS
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.
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)
%TERTIARY
REACTIONARYREPARATIVE
PULP
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
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.
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
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.
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 cytoplasmicgranules
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 innucleus
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
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.
MATRIX
FIBREGROUND SUBSTANCE
• COLLAGEN
• ELASTIN
• FIBRONECTIN
• LAMILIN
GAGPR
OTEOGLYCAN
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
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
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
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.
• Maintain tissue’s physical properties and
integrity
• Control of growth and development and
repairs
• Control of cell migration
• Control of diffusion of macromolecules
FUNCTIONS OF PULPAL EXTRACELLULAR MATRIX
• 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
PULPAL VASCULATURE
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 THIRDMIDDLE THIRD
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
PULPAL VASCULATURE
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)
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.
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.
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.
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.
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.
A-delta fibers Conduction velocity 2-30 m/s Lower threshold Involved in fast, sharp pain Stimulated by hydrodynamic
stimuli Sensitive to ischemia Sharp pain
C fibers Conduction velocity 0-2 m/s Higher threshold Involved in slow, dull pain Stimulated by direct pulp
damage Sensitive to anesthetics Dull pain
A-beta fibers Conduction velocity 30-70
m/s Very low threshold, non-
noxious sensation 40% of myelinated fibers in
pulp Functions not fully known
Non-myelinated sympathetic fibers
Conduction velocity 0-2 m/s Post-ganglionic fibers of
superior cervical ganglion Vasoconstriction &
Vasodilation.
INNERVATION
P e n e t r a t i o n i n t o D e n t i n
Plexus of Rashkow
Nerve ending patterns
46
FUNCTIONS OF DENTAL PULP
INDUCTIVE
FORMATIVE
NUTRITIVE
PROTECTIVE
DEFENSE
INDUCTIVE
Induce oral epithelial differentiation into dental lamina and enamel
organ formation.
Also induces developing enamel organ to become a particular type
of tooth.
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.
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 56:32,2002Kramer IRH, The vascular architecture of the human pulp, Arch Oral Bio 2:177, 1960
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: 488-495, 2006
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
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.
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.
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.
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.
Goga, R.; N. P. Chandler & A. O. Oginni (2008). "Pulp stones: a review". International Endodontic Journal 41: 457–468.
CLASSIFICATION
True denticles
False denticles
Diffused calcificati
ons
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.
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
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.
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 contain DM in regions
of previous liquefaction necrosis.
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
CAVITY DEPTH
1mm – Shields Pulp
0.5- 0.25mm – Tertiary Reactive Dentin
0.25mm> ~ Odontoblasts die & Reperative dentin is
formed very fast.
CAVITY DRYING
Strong capillary forces
Outward flow of Dentinal fluid/Odontoblast displacement
This is replaced by fluid from the pulp
Stimulates Nociceptors
Produces Pain
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
STEM CELLS OF PULP
Hematapoietic Stem Cells (HSC)
Mesenchymal Stem Cells (MSC)
Embryonic Stem Cells