Dental pulp / oral surgery courses

DENTALDENTAL
PULPPULP
INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMY
Leader in continuing Dental EducationLeader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 IntroductionIntroduction
 EmbryologyEmbryology
 AnatomyAnatomy
 Structural organization of pulpStructural organization of pulp
 Cells of pulpCells of pulp
 Extra-cellular matrixExtra-cellular matrix
 Circulation of pulpCirculation of pulp

Metabolism of pulpMetabolism of pulp
Innervation of pulpInnervation of pulp
Functions of pulpFunctions of pulp
Pulp of deciduous toothPulp of deciduous tooth
Pulp calcificationPulp calcification
Age changesAge changes
Clinical significanceClinical significance

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INTRODUCTIONINTRODUCTION
The Pulp is a soft mesenchymalThe Pulp is a soft mesenchymal
connective tissue that occupies pulpconnective tissue that occupies pulp
cavity in the central part of the teeth.cavity in the central part of the teeth.
It is a special organ because ofIt is a special organ because of
the unique environmentthe unique environment

SALIENT FEATURESSALIENT FEATURES
Enclosed within dentinEnclosed within dentin
Resembles embryonic connective tissueResembles embryonic connective tissue
Houses a number of tissuesHouses a number of tissues
Microcirculatory system with no collateralMicrocirculatory system with no collateral
systemsystem
Retains ability to form dentin throughoutRetains ability to form dentin throughout
lifelife

DEVELOPMENTDEVELOPMENT
During the 8During the 8thth
week of IUL, there is condensationweek of IUL, there is condensation
of the mesenchmye under the enamel organ-of the mesenchmye under the enamel organ-
Dental papilla.Dental papilla.
The enamel organ enlarge and enclose theThe enamel organ enlarge and enclose the
dental papilla in their central portiondental papilla in their central portion
Dental papilla controls the morphology & type ofDental papilla controls the morphology & type of
tooth to be formedtooth to be formed
Dental papilla shows:Dental papilla shows:
extensive proliferation of cellsextensive proliferation of cells
high vascularityhigh vascularity

Following the differentiation of the IEE intoFollowing the differentiation of the IEE into
ameloblasts, odontoblast differentiate from theameloblasts, odontoblast differentiate from the
peripheral cells of dental papillaperipheral cells of dental papilla
Well organized capillaries are found at beginningWell organized capillaries are found at beginning
of dentinogenesisof dentinogenesis
Capillaries crowd around the odontoblast duringCapillaries crowd around the odontoblast during
active dentinogenesisactive dentinogenesis
Rim of the enamel organ(IEE & OEE) is theRim of the enamel organ(IEE & OEE) is the
cervical loop.cervical loop.
Root formation is carried out by the proliferationRoot formation is carried out by the proliferation
of cells at the cervical loop.of cells at the cervical loop.

Dental PapillaDental Papilla
Dental papilla capped byDental papilla capped by
the enamel organthe enamel organ

ANATOMY OF PULPANATOMY OF PULP
52 pulp organs – 32 + 2052 pulp organs – 32 + 20
Total pulp volume in permanent teeth isTotal pulp volume in permanent teeth is
0.38 cc. with mean being 0.02 cc.0.38 cc. with mean being 0.02 cc.
The pulp cavity is divided into coronalThe pulp cavity is divided into coronal
pulp and radicular pulppulp and radicular pulp

CORONAL PULPCORONAL PULP
It is the pulp occupying the pulp chamberIt is the pulp occupying the pulp chamber
of the crown of the toothof the crown of the tooth
In young teeth it resembles the shape ofIn young teeth it resembles the shape of
the outer dentinthe outer dentin
It has six surfaces: occlusal, mesial, distal,It has six surfaces: occlusal, mesial, distal,
buccal, lingual and floorbuccal, lingual and floor
Pulp horns are projections into the cuspPulp horns are projections into the cusp
This pulp constricts at the cervical regionThis pulp constricts at the cervical region
where it continues as the radicular pulpwhere it continues as the radicular pulp

RADICULAR PULPRADICULAR PULP
It is the pulp occupying the pulp canals of theIt is the pulp occupying the pulp canals of the
root of the toothroot of the tooth
In the anterior tooth it is single and in theIn the anterior tooth it is single and in the
posterior teeth it is multipleposterior teeth it is multiple
The radicular portions of the pulp is continuousThe radicular portions of the pulp is continuous
with the periapical tissueswith the periapical tissues
It is more fibrous & whitish color, which protectsIt is more fibrous & whitish color, which protects
the neurovascular bundlethe neurovascular bundle
As age advances the width of the radicular pulpAs age advances the width of the radicular pulp
is reduced, and so is the apical foramenis reduced, and so is the apical foramen

APICAL FORAMENAPICAL FORAMEN
It forms the portal of entry or exit for theIt forms the portal of entry or exit for the
contents of the pulpcontents of the pulp
Mean size:Mean size:
Maxillary teeth – 0.4 mmMaxillary teeth – 0.4 mm
Mandibular teeth – 0.3 mmMandibular teeth – 0.3 mm
Migration or horizontal pressure causesMigration or horizontal pressure causes
the apex to tilt, changing the position ofthe apex to tilt, changing the position of
the apical foramenthe apical foramen

There may be 2-3 foramina split byThere may be 2-3 foramina split by
cementum or dentin- APICAL DELTA.cementum or dentin- APICAL DELTA.
Largest in palatal root of maxillary teethLargest in palatal root of maxillary teeth
and distal root of mandibular teeth.and distal root of mandibular teeth.
It is usually 0.5-0.75 mm occlusal to theIt is usually 0.5-0.75 mm occlusal to the
anatomic apex.anatomic apex.

Apical ForamenApical Foramen
NeurovascularNeurovascular
bundle enteringbundle entering
pulp through thepulp through the
foramenforamen

ACCESSORY CANALACCESSORY CANAL
Leading laterally from the radicular pulpLeading laterally from the radicular pulp
into the periodontal tissue.into the periodontal tissue.
Present in the apical third of the root.Present in the apical third of the root.
Formed due to premature loss of HERS orFormed due to premature loss of HERS or
when developing root encounters a bloodwhen developing root encounters a blood
vessel.vessel.
Overall occurrence is 33%Overall occurrence is 33%
May also be present at the furcationMay also be present at the furcation
region.region.

Accessory CanalsAccessory Canals

CANAL CONFIGURATIONCANAL CONFIGURATION
Four types of canal configuration present in oneFour types of canal configuration present in one
root, given byroot, given by WeineWeine in 1982in 1982
Type IType I – Single canal from pulp chamber to apex.– Single canal from pulp chamber to apex.
Type IIType II – Two canal leaving the canal and merging to– Two canal leaving the canal and merging to
form a single canal short of the apex.form a single canal short of the apex.
Type IIIType III – Two separate distinct canal from the chamber– Two separate distinct canal from the chamber
to the apex.to the apex.
Type IVType IV – One canal leaving the chamber and divided– One canal leaving the chamber and divided
into two separate distinct canal.into two separate distinct canal.

VERTUCCI CLASSIFICATIONVERTUCCI CLASSIFICATION

MORPHOLOGIC ZONES OF
PULP
ODONTOBLAST LAYER
CELL-POOR ZONE
CELL-RICH ZONE
PULP PROPER
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ODONTOBLAST LAYER
• Present next to predentin with
odontoblastic process passing thro
predentin into dentin
• Contains nerve fibers(Aδ),
capillaries,dendritic cells
• Coronal pulp
• Cells tall columnar, palisading
• Layers of 3-4 cells effect
• More odontoblasts per unit area

• Cells in the mid-root region are
cuboidal and appear flattened at the
apical region.
• No.of odontoblasts per unit area in
the radicular pulp is reduced
• Neighbouring odontoblasts exhibit
junction complexes.

CELL POOR ZONE
 Present coronal pulp next to
odontoblast layer,also called WEIL’S
zone
 40µ wide & relatively free of cells
 Traversed by
blood vessels
unmyelinated nerves
cytoplasmic process of fibroblasts

 Nerve plexus of Rashkow
 Presence/ absencce of this zone
depends on the functional status
 Relatively diminished in
younger pulp
older pulp

CELL RICH ZONE
 Present in subodontoblastic layer
 Prominent in coronal pulp
 Contains more proportions of fibroblast
than pulp proper
 Also contains macrophages, dendritic cells
and lymphocytes.
 Zone formed due to migration of cells from
pulp proper
 Mitosis seen when dead odontoblasts are
replaced

PULP PROPER
▪ It is the central mass of the pulp
▪ Contains larger blood vessels and
nerves
▪ Pulpal cells and fibroblasts are also
seen

Structural Organization of pulp

CELLS OF PULP
ODONTOBLASTS
FIBROBLASTS
UNDIFFERENTIATED CELLS
IMMUNOCOMPETENT CELLS
MAST CELLS

ODONTOBLAST
Highly differentiated cells derived from
neural crest cells
40μ tall and 5-7μ wide
During active phase, cells show increase in
ER, golgi apparatus & secretory vesicles
After primary dentin formation dentin
forming activity slows down with decrease
in no.of organelles
Quiescent odontoblast are shorter &
contain autophagic vacuoles. These
vacuoles mediate a reduction in the
organelle number

ODONTOBLASTIC PROCESS
It is a direct extention from cell body
into the dentinal tubule
Diameter 3-4μ
No cell organelles
Has well developed cytoskeleton with
microfilaments & microtubules. Mainly
composed of protein- tubulin, actin
and vimentin.

JUNCTIONAL COMPLEX
Neighbouring odontoblasts exhibit a series
of junctional complexes
They promote cell to cell adhesion and play
a role in maintaining polarity of
odontoblasts.
Junctional complexes may be
zonula adherens - desmosomes
nexuses - gap junctions
zonula occludens - tight junctions.

Spot desmosomes present in apical
part of odontoblasts, mechanically
join the cells together.
Tight junctions seen in apical part of
odontoblasts. Responsible for
permeability between predentin and
pulp
Gap junctions provide low resistance
pathway for passage of electric
signals

JUNCTIONAL COMPLEXES

FUNCTIONS OF ODONTOBLASTS
Synthesis of organic matrix
Synthesis of non collagenous
substances like sialoprotein,
phosphophoryn, osteocalcin,
osteonectin& osteopontin
Intracellular accumulation of calcium
Degradation of organic matrix

FIBROBLASTS
Maximum in number and have the
capacity to synthesise and maintain
connective tissue matrix
Main functions
synthesise type I & type III collagen
synthesise non-collogenous protein
matrix- proteoglycans & GAGs
Synthetic cells have branched cytoplasmic
extentions with nucleus at one end of the
cell. Common in young pulp

Older cells are spindle shaped with less
organelles. When stimulated, active
synthetic phase may be reactivated.
Involved in degradation of extracellular
matrix by action of lysosomal enzymes. Eg:
Collagenase, gelatinase, stromelysin
Suggested that inflammatory cytokines &
bacterial byproducts stimulate fibroblasts to
degrade the pulpal connective tissues
during pulp inflammation

Fibroblast
H&Estain
Immunohistochemical
method

UNDIFFERENTIATED MESENCHYME
These mesenchymal cells are distributed
through out the pulp, frequently around the
perivascular area
They are stellate shaped with a high
nucleus : cytoplasmic ratio
Difficult to differentiate from fibroblast
under light microscopy
Under adequate stimulus they may
differentiate into odontoblast or fibroblast.
In older pulp, their number and ability to
differentiate comes down

IMMUNOCOMPETENT CELLS
They play a major role local inflammation
and immunity.
They are recruited from blood stream &
remain as transient inhabitants in pulp
These cells are
Lymhpocytes
Macrophages
Dendritic cells
Mast cells

LYMPHOCYTES
They are responsible for specific
immune response.
They are broadly divided into
▪ T lymphocytes
▪ B lymphocytes

HUMORAL IMMUNITY
B- lymphocytes
▼
Plasma cells
▼
Carry membrane bound antibody to
specific antigens
▼
HUMORAL IMMUNITY

Plasma Cell
Peripheral arrangement of chromatin in
nucleus www.indiandentalacademy.com

CELL-MEDIATED IMMUNITY
T- lymphocytes
▼
Specific immune response to protein antigens
▼ ▼
Helper T cells Cytotoxic T cells
( CD 4+) (CD 8+)
▼ ▼
Coordinating Cell Lysis of cells
mediated & humoral carrying foreign antigen
immunity
▼ ▼
CYTOKINES CELL-MEDIATED IMMUNITYwww.indiandentalacademy.com

T- helper cell
▼
Activated T helper cell
▼
Release of cytokines
▼ ▼
Th1 cells Th2 cells
▼ ▼
IL-2 & IFNγ IL-4,5,6
▼ + ▼+
Macrophages Proliferation & diff
of B lymphocytes

LYMPHOCYTES IN PULP
Present along the walls of blood
vessels
CD8+ T lymphocytes > CD4+ T
lymphocytes
Involved in initial immunodefense
B lymphocytes very rare
Plasma cells may be present in
coronal pulp

LYMPHOCYTES IN PULP

MACROPHAGES
 Derived from hemopoietic stem cells of
monocyte-macrophage lineage
 Primarily phagocytic in nature
 They phagocytize
foreign particles, eg microbes
self tissues
injured or dead cells
 Characterised by irregular surface protrusions,
well developed golgi complex, lysosomes &
prominent RER
 Play a role in immunity by helping in T
lymphocyte activation
 Defense role by secretion of various bioactive
materials

MACROPHAGES IN PULP
Described as histiocytes
Located close to blood vessel
Have several phenotypes
They express varying combinations of
several macrophage associated antigens
and so help in T lymphocyte activation

Macrophages
Dark staining nucleus with cytoplasmic
granules

DENDRITIC CELLS
Discrete populations of
hematopoetically derived leucocytes
Characterised by
▪peculiar dendritic morphology
▪expression of high amount of
class II MHC molecules
▪high motility
▪capacity of antigen presentation
to T lymphocytes

More in non lymphoid tissue
Mainly act as immunosurveillance
component
In pulp, class II MHC molecules expressing
(HLR-DR) cells form a continuous reticular
network throughout the pulp
They are particularly subjacent to
odontoblastic layer and may a major role in
encountering exogenous antigens

Following ingestion of invading antigen
▼ ▼
Migrating to regional Locally antigens to
Lymphnodes & (+) naïve memory t lymphocytes
T lymphocytes
▼ ▼
1° IMMUNE RESPOSE when second attack of
antigens, (+) of T
lymphocytes
▼
2° IMMUNE RESPONSE
ACTION OF DENDRITIC CELLS

MAST CELLS
Occur in small groups in relation to blood
vessels
Present only during pulpal inflammation
Cytoplasmic granules of these cells contain
▪Heparin- anticoagulant
▪Histamine- inflammatory mediator

EXTRACELLULAR MATRIXEXTRACELLULAR MATRIX
Connective tissue fibersConnective tissue fibers
▪▪ CollagenCollagen
▪▪ ElastinElastin
▪▪ FibronectinFibronectin
 Ground substanceGround substance
▪▪ ProteoglycansProteoglycans
▪▪ GlycosaminoglycansGlycosaminoglycans
 Basement membraneBasement membrane

COLLAGENCOLLAGEN
 Extra cellular structural protein, major
constituent of connective tissue
 It has a triple helical domain, formed by 3
polypeptide chains(αchains) bound by hydrogen
bonds & hydrophobic interaction
 Fibrils display characteristic striation at intervals
of 67nm. Hallmark for identification of collagen
fibrils.

Biosynthesis Of CollagenBiosynthesis Of Collagen
Formation of polypeptide chains by
polyribosomes of RER
▼
Hydroxylation of proline &lysine
▼
Glycosylation of hydroxylysine
▼
Assembly of polypeptide chains to form
procollagen with a triple helix confugaration
▼

Transport to golgi complex, where procollagen
molecules are packed in secretory vesicles
▼
secretion of procollagen molecules into
extra cellular space
▼
aggregation to form collagen fibrils
▼
reinforcement & insolubilization of fibrillar
structure by cross linking

Collagen Fiber

 Collagen fibers are inelastic but have great
tensile strength
 It is the major organic component of pulp
 Type I & III are seen in pulp of which Type I is of
higher proportion
 Type I:
▪present as thick striated fibrils
▪responsible for pulp architecture
 Type III:
▪thinner fibrils, mainly distributed in cell
free & cell rich zones
▪contributes to the elasticity of pulp

 Type IV:
▪present along the basement membrane of
blood vessels
 Type V & VI:
▪seen to form dense meshwork of thin micro
fibrils through out the stroma
 Interodontoblast collagen fibers or VON KORFF
fibers which extends into predentin may be
composed of type I, III &VI

 Collagen turnover is maintained by pulp
fibroblasts
 During bacterial infection & inflammation,
collagenolytic activity is accelerated following
collagenase produced by bacteria, PMN &
fibroblasts
 Collagen synthesis is accelerated during
reparative dentin formation.

Collagen FiberCollagen Fiber
Seen in relation with fibroblasts

 Elastin molecules form the unit structure of
Elastic fibers
 These elastin molecules join to form a random
coil structure
 This has the ability to expand and contract like a
rubber band.
 Elastic fibers are first formed in bundles of thin
micro filaments called Oxytalan fibers
 Elastin is then deposited inbetween oytalan
fibers to form elastic fibers.
 Always associated with larger blood vessels
ELASTIC FIBERELASTIC FIBER

Elastic FiberElastic Fiber
Verhoeff's method stains the fibers blackVerhoeff's method stains the fibers black

 It is a multifunctional stromal glycoprotein that
exists as
• a circulatory plasma protein
• a protein that attaches to cells
• insoluble fibrils forming a part of the extra
cellular matrix
 It plays a role in cell-cell & cell-matrix adhesion
 Has a major effect on the proliferation,
differentiation & organization of cells
 Seen around the blood vessels
FIBRONECTINFIBRONECTIN

 Also found in odontoblast layer with fibers
passing into predentin suggesting its role in the
formation of Von Korff fibers
 Due to its close interaction with odontoblasts &
extracellular fibers, fibronectin helps to maintain
cell morphology & provide a tight seal at this site
 Fibronectin may be involved in cell migration &
anchorage in the wound healing process of the
connective tissue of pulp

 It regulates the migration and differentiation of
secondary odontoblasts
 Adherent property of fibronectin is due to cell
surface glycoprotein receptors called Integrins
 Integrins are composed of two non-covalently
linked polypeptide chains, αand β. There are 30
different types of integrins

GROUND SUBSTANCE
It is a structureless mass, gel-like
consistency, makes up the bulk of the pulp
Consists complexes of proteins,
carbohydrate and water.
Broadly classified as
Glycoaminoglycans
Proteoglycans

GLYCOSAMINOGLYCANS
GAG are branched polymers of glucosamine &
galactoseamine, along with ester sulfate
groups, uronic acid & carboxyl group
4 main types:
Chondroitin sulphate/dermatan sulphate
Keratin sulphate
Heparin sulphate
Hyaluronic acid (non-sulphated)
GAG found in pulp is mainly chondroitin
sulphate, dermatan sulphate & hyaluronic acid

PROTEOGLYCANS
Proteoglycans consists of a central protein
core with side chains of GAGs
Due to presence of various structural groups
of GAG, proteoglycans are hydrophilic & act as
polyanions
Thus proteoglycans carry high –ve charge that
prevent diffusion of larger molecules but
attract cationic material.
Proteoglycans occupy larger area and they
provide protection against compressionwww.indiandentalacademy.com

They have binding sites for growth factors
thus may act as a reservoir for bioactive
molecules
Syndecan, a proteoglycan located on cell
membrane has an extra cellular domain that
binds with extra cellular glycoprotein & a
cytoplasmic domain that links with the
cytoskeleton. Thus regulate cell function

During dentinogenesis, the ground substance
show affinity for collagen and influence
fibrinogenesis
Chondroitin sulfate strong capacity to bind
with calcium and help in mineralisation
Decorin is suggested to be synthesized by
odontoblasts and transported through the
process which may play a role in mineral
nucleation
ROLE IN PULP

 It is a sheet like arrangement of extra cellular
protein matrix at the epithelial-mesenchymal
interface
 Composed of 2 layers
lamina densa - electron dense
lamina lucida - electrolucent
 Basement membrane is a product of
connective tissue and epithelium
BASEMENT MEMBRANE

 It is composed of
collagen type IV
laminin- adhesive glycoprotein
fibronectin
heparin sulfate
 Collagen IV provides binding sites for the rest
of basement membrane components
 Laminin binds to both cells of conective tissue
and epithelium
 In mature pulp, basement membrane forms
interface along endothelial cells & schwann
cells www.indiandentalacademy.com

 FUNCTIONS:
▪ act as sieve between epithelium &
connective tissue
▪ helps in organisation & differentiation by
enabling interactions between
extracellular molecules & cell surface
receptors
Eg. Odotoblasts during tooth
development

CIRCULATION OF THE PULPCIRCULATION OF THE PULP
Pulp organ is extensively vascularised withPulp organ is extensively vascularised with
blood vessels arising from superior & inferiorblood vessels arising from superior & inferior
alveolar arteriesalveolar arteries
It is critically important in maintaining tissueIt is critically important in maintaining tissue
homeostasishomeostasis
It has ability to undergoIt has ability to undergo
Dynamic response to injury by altering localDynamic response to injury by altering local
capillary filtration ratescapillary filtration rates
Initiate immunologic response to injury &Initiate immunologic response to injury &
inflammationinflammation

Organization of pulp vasculatureOrganization of pulp vasculature
Pulp is a micro circulatory system which lacksPulp is a micro circulatory system which lacks
true arteries & veinstrue arteries & veins
The largest vessels are arterioles & venulesThe largest vessels are arterioles & venules
which regulate the local interstitial environmentwhich regulate the local interstitial environment
They enter the tooth through the apical foramenThey enter the tooth through the apical foramen
Pulp tissue pressure is 14cm HPulp tissue pressure is 14cm H2200

Organization of pulp vasculatureOrganization of pulp vasculature
H&E section showing the neurovascular bundleH&E section showing the neurovascular bundle

ARTERIOLES:ARTERIOLES:
ArteriolesArterioles
(50(50μμ diameter)diameter)
▼▼
Terminal arteriolesTerminal arterioles
▼▼
PrecapillariesPrecapillaries
▼▼
MetarteriolesMetarterioles
▼▼
Capillaries (8Capillaries (8μμ))

The branching point of terminal arterioles is
characterized by smooth muscle clumps that
act as sphincters which are under the local
cellular & neuronal control
Thus pulpal inflammation elicits a localised
circulatory response restricted to the area of
inflammation
Arteriolar pressure- 43mm Hg.

Apical third Middle third
PULP VASCULATURE

Microcirculatory SystemMicrocirculatory System
Arterioles & venulesArterioles & venules

CAPILLARIES:
•Function as exchange vessels regulating
the transport or diffusion of substances between
blood and local interstitial tissue elements
• They consists of single layer of
endothelium surrounded by basement
membrane
• Capillary pressure-35 mmHg
• Capillary wall is 0.5μ thick & acts as semi
permeable membrane

Based on the property of semi permeability,
capillaries may be grouped as
Class I: Fenestrated capillaries
Class II: Continuous capillaries
(non fenestrated)
Class III: Discontinuous capillaries
Class IV: Tight junction capillaries
Class I & II are present in the dental
pulp

Capillary network is organized in 3 layers
I. Terminal capillary network located in the
“odontoblastic layer”
II. “Capillary network” present adjacent to the
odontoblastic layer & consists of pre capillary
& post capillary vessels
III. Venular network of vessels
During aging & decreased metabolism these
layers appear as single layer

SEM shows extensive arborization of capillariesSEM shows extensive arborization of capillaries
from the metarteriolesfrom the metarterioles

VENULES:
Collecting venules receive pulpal blood flow
from the capillaries & transfer it to the venules
Arterio-venous anastomosis permits direct
shunting from arterioles to venules
Venular pressure-19mmHg

Lymphatic vessels are formed from a fine
meshwork of small, thin walled lymph capillaries
Lymph capillaries coalesce to form larger
lymphatic vessels with valves
They start as blind openings near Weil’s zone &
odontoblastic layer
The larger lymphatic vessels run along the blood
vessels & nerves
LYMPHATICSLYMPHATICS

Multiple collecting lymph vessels exit though the
apical foramen & drain lymph from pulp into the
periodontium
Role in pulp:
They remove high molecular solutes from
the interstitial fluids thus maintain interstitial
COP
They transport lymph to the regional lymph
node before it enters into the blood vessels. This
provides an immuno surveillance function

REGULATION OF PULPALREGULATION OF PULPAL
BLOOD FLOWBLOOD FLOW
1. Metabolic regulation
2. Neuronal regulation
a. Sympathetic fibers
b. Parasympathetic fibers
c. Peptidergic afferent fibers
3. Endocrine & paracrine regulation

METABOLIC REGULATIONMETABOLIC REGULATION
The arteriolar vascular tone is regulated by
locally released metabolic by products
These by products are known to cause direct
vasodilatation
I ncrease blood flow due to vaso dilatation is
seen when there is
•  Adenosine
•  PO2
•  pH
•  CO2

NEURONAL REGULATIONNEURONAL REGULATION
Sympathetic nerves
 These nerve fibers terminate as free nerve
endings in the pulp & innervate the arterioles
 Depolarization of these fibers leads to the
release of neurotransmitters which causes
constriction of blood vessels. This causes
reduction in pulpal blood flow by 80%
 Distribution of sympathetic fibers is greater in
the pulp horns near odontoblast region &
lowest in the apical region

Reflex excitation of sympathetic nervous
system either by hypotension or decrease in
O2 transport causes pulpal vasoconstriction
Stimulation of α or β receptors in the blood
vessels causes vasoconstriction or
vasodilatation respectively
Neurotransmitter released are norepinephrine,
NPY, ATP

Sympathetic InnervationSympathetic Innervation
Sympathetic nerve fibers forming plexus
around arterioles

Parasympathetic nerves:
Plays a minor role in the regulation of blood flow
Two main neurotransmitters derived from
parasympathetic nerves are
Acetylcholine
Vasoactive intestinal polypeptide
Causes vasodilatation

Peptidergic afferent fibers:
Sensory fibers innervating the pulp have afferent
action like way of releasing certain peptide
Sensory derived neuropeptides terminate near
the blood vessels, they are
Substance P
Calcitonin gene related peptide
(CGRP)
Neurokinin A

Chiefly released from C fibers & thin myelinated
Aδ fibers
Primarily cause vasodilatation & increases
pulpal blood flow
CGRP > substance P in increasing blood flow

PARACRINE/ENDOCRINEPARACRINE/ENDOCRINE
REGULATIONREGULATION
Endocrine regulation is through circulating
adrenaline and nor-adrenaline
There are several paracrine factors that regulate
the blood flow
Bradykinin
Prostaglandin
Histamine

Bradykinin:
Produced locally at the site of inflammation
kallikerin
Killinogen ---------------► Bradykinin
Increases pulpal blood flow
Provokes prostaglandin release
Prostaglandin:
Enhance the effect of bradykinin
Found in irreversible pulpitis
PGE2 increases pulpal blood flow by 60%

Histamine:
More than an increase in blood flow, they
cause profound increase in plasma
extravasation

DETECTIONDETECTION OF PULP VITALITYOF PULP VITALITY
• Laser Doppler flowmetry:
Based on the principle that reflected light from
blood flow will demonstrate a Doppler effect,
depending on the relative velocity of the blood flow &
probe
• Pulse oximeter:
Based on evaluating Oxygen saturation of the
tissues
• Transmitted-light photoplethesmography
• Hughe’s Probye Camera
• Dual wavelength spectrometry

METABOLISMMETABOLISM
 Metabolism has been studied by measuring the rate of
O2 consumption & production of CO2 lactic acid by
pulp tissue
 Radiospirometry is also used to evaluate the
metabolism. Pulp tissue is placed in 14 C labeled
substrates, such as succinate & rate of appearance of
CO2 is measured.
 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 decrease in O2
consumption as 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
 Several dental materials have shown to inhibit O2
consumption. Eg, ZOE, Ca(OH)2 & silver amalgam
 Pulpal irritation causes increase in cycloxygenase
products, which is inhibited by ZOE
 As cellular composition reduces, the rate of oxygen
consumption decreases.

INNERVATIONINNERVATION
 Principle role is to help in conscious recognition of
irritants to the pulp, which gives the opportunity to
have the problem corrected before irreversible effects
can occur
 Nerve fibers, mylinated & unmyelinated , enter the
tooth through the apical foramen
 Dental pulp contains sensory and motor fibers to
fulfill the vasomotor and defense function
 Sensory afferent fibers are branches of maxillary &
mandibular divisions 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 Aδ and C fibers
 Above the cell rich zone,myelinated fibers begin to
lose their myelin sheath.
 In the cell free zone, they form a rich network
responsible for pain.
 Many of these fibers pass between the odontoblastic
zone.

 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.

Types of nerve fibers

Factors influencing transmission of impulses

Neuropeptides in PulpNeuropeptides in Pulp
 Neuropeptides are proteins that have been associated
with central & peripheral nervous system.
 Following are the neuropeptides demonstrated in
pulp:
▪Originate from trigeminal ganglion(C fibers)
Substance P
CGRP
Neurokinin A

▪ Sympathetic neuropeptide
Neuropeptide Y
▪ Parasympathetic neuropeptide
Vasoactive intestinal polypeptide
Functional Role:
1. Inreased vascular permeability
2. Promote phagocytosis
3. Stimulate lymphocytes
4. Stimulate growth of connective tissue
5. Stimulate Leukochemotaxis

6. Promote wound healing
7. Release of inflammatory mediators such as
Histamine, PGE2, collogenase,IL-2, IL-6 & TNF
8. Vasodilatation, except NYP which causes
vasoconstriction.

FUNCTIONS OF DENTAL PULPFUNCTIONS OF DENTAL PULP
 INDUCTIVE
 FORMATIVE
 NUTRITIVE
 PROTECTIVE
 DEFENSE

INDUCTIVEINDUCTIVE
 It induces epithelial differentiation into
dental lamina & enamel organ
 It also induces the enamel organ to become
a particular type of tooth

FORMATIVEFORMATIVE
 Pulp induces dentin formation that surrounds &
protects the pulp
 This involves formation of primary & secondary
dentin
 The primary dentin is tubular & regularly
arranged. Formed before root closure
 Secondary dentin contain fewer tubules & is
formed after root closure

NUTRITIVENUTRITIVE
 Dental pulp maintains the vitality of dentin by
providing O2 & nutrients to the odontoblasts
 Also provides continuing source of dentinal fluid
 Nutrition made possible by rich peripheral
capillary network

PROTECTIVEPROTECTIVE
 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
& rate of blood flow & hence the intrapulpal
pressure

DEFENSEDEFENSE
 When irritated or injured the pulp will respond by
1. Dentinal pain
2. Smear layer formation
3. Tubular sclerosis
4. Irritation dentin formation
5. Inflammation of subjacent connective
tissue

SMEAR LAYERSMEAR LAYER
 Scaling, abrasion, attrition, caries, tooth
preparation leave microcrystalline debris or a
smear layer that extends into the dentinal tubules
(smear plugs)
 Studies suggests that after several weeks, with the
assistance of dentinal fluid & saliva, this smear
layer undergoes mineralization
 Harbarbours bacteria
 Substitutes Potassium oxalate, Ferric oxalate 5%

TUBULAR SCLEROSISTUBULAR SCLEROSIS
 Mild to moderate irritation results in continued
peritubular dentin formation- physiologic sclerosis
& intratubular calcification- reactive or pathologic
sclerosis
 Peritubular dentin sclerosis:
It is a calcified secretion of odontoblastic process.
Secretory vesicles form odontoblastic process are
released to form the peritubular dentin matrix. This
type of dentin is more calcified than intertubular dentin
due to more calcium in the dentinal environment

 Intratubular sclerosis:
It is a physico-chemical process caused by
precipitation of mineral salts within the dentinal
tubules. It is the re-crystallisation of Ca & PO4 ions
previously demineralised by carious process. Another
source may be supersaturation of dentinal fluid with
Ca & PO4 ions which are precipitated

TUBULAR SCLEROSIS

IRRITATIONIRRITATION DENTINDENTIN
 Stimuli like operative procedures, abrasion or caries can
result in rapid dentin formation- Tertiary dentin
 Tubules are irregular or may be absent
 During the formation of tertiary dentin, the cells may get
entrapped in the matrix- Osteodentin
 Depending on the type of stimuli, Irritation dentin can be:
Reactionary dentin
Reparative dentin

Tertiary Dentinogenesis

Factors Influencing TertiaryFactors Influencing Tertiary
DentinogenesisDentinogenesis
ReactionaryReactionary DentinogenesisDentinogenesis::
Shallow cavityShallow cavity-- RDT >0.5mmRDT >0.5mm--  RDRD
Deep cavityDeep cavity -- RDT 0.25RDT 0.25--0.5mm0.5mm--  RDRD
Very deep cavityVery deep cavity -- RDT 0.008RDT 0.008--0.25mm0.25mm--  RDRD
ReparativeReparative DentinogenesisDentinogenesis::
Pulp exposurePulp exposure-- RDT <0.008mmRDT <0.008mm –– Reparative dentinReparative dentin
formationformation

PULP OF DECIDUOUSPULP OF DECIDUOUS
TEETHTEETH
 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

 Primary pulp functions for a mean of 8.3
years. This time can be divided into
three periods
 Pulp organ growth
Time of crown and root development
 Pulp maturation (3 years, 9 months)
Time after root completion to
beginning of root resorption
 Pulp regression (3 years, 6 months)
Beginning of root resorption to
exfoliationwww.indiandentalacademy.comwww.indiandentalacademy.com

PULP CALCIFICATIONSPULP CALCIFICATIONS
► It is a common occurrence with incidence of 50%It is a common occurrence with incidence of 50%
of all teethof all teeth
► Size may range from microscopic particle toSize may range from microscopic particle to
stones that may occlude the pulp chamberstones that may occlude the pulp chamber
► Composed of carbonated hydroxyapitite crystalsComposed of carbonated hydroxyapitite crystals
► Pulp calcification may bePulp calcification may be
Pulp stonesPulp stones
Diffuse calcificationsDiffuse calcifications
Calcific MetamorphosisCalcific Metamorphosis

TrueTrue DenticleDenticle::
?? Round/ ovoid, with smooth surfaces & concentricRound/ ovoid, with smooth surfaces & concentric
lamellaelamellae
?? Appear to grow by addition of collagen fibers toAppear to grow by addition of collagen fibers to
their surfacetheir surface
?? They are believed to be formed around HERS.They are believed to be formed around HERS.
These epithelial remnants induce differentiation ofThese epithelial remnants induce differentiation of
odontoblastodontoblast causingcausing denticledenticle formationformation
?? TheyThey contiancontian dentinal tubules & are frequentlydentinal tubules & are frequently
found near the root apexfound near the root apex

True DenticleTrue Denticle
► H&E sectionH&E section
of trueof true
denticledenticle
► HigherHigher
magnificationmagnificationwww.indiandentalacademy.com

False Denticles:False Denticles:
They have a rough surface no particular shape &They have a rough surface no particular shape &
laminationslaminations
Grow due to mineralization of preformed collagenGrow due to mineralization of preformed collagen
fibersfibers
Cause of such calcification may be, degeneratingCause of such calcification may be, degenerating
cells, blood thrombi or collagen fibrils all of whichcells, blood thrombi or collagen fibrils all of which
form a nidi for calcificationform a nidi for calcification
Usually present in the pulp chamber.Usually present in the pulp chamber.

False DenticleFalse Denticle
False calcification seen along the walls of theFalse calcification seen along the walls of the
blood vesselblood vessel

Diffuse CalcificationDiffuse Calcification
They appear as irregular deposits in theThey appear as irregular deposits in the
pulppulp
The pulp organ may be free of anyThe pulp organ may be free of any
pathology, but may exhibit these changes inpathology, but may exhibit these changes in
the rootsthe roots

Diffuse calcificationDiffuse calcification
Diffuse calcification of the pulp, seen alongDiffuse calcification of the pulp, seen along
with pulp fibrosiswith pulp fibrosis

Calcific MetamorphosisCalcific Metamorphosis
 Luxation of teeth as a result of trauma may resultLuxation of teeth as a result of trauma may result
in calcific metamorphosisin calcific metamorphosis
 Usually results in partial or complete radiographicUsually results in partial or complete radiographic
obliteration of the pulp chamberobliteration of the pulp chamber
 Resembles cementum or bone on dentinal wallsResembles cementum or bone on dentinal walls
 Teeth may present with a yellowish hueTeeth may present with a yellowish hue
 TraumaTrauma →→disruption of blood flow to the pulpdisruption of blood flow to the pulp→→
pulpal infarctpulpal infarct→→ cells from periodontium proliferatescells from periodontium proliferates
& replace the infarct tissue& replace the infarct tissue

AGE CHANGESAGE CHANGES
 Formation of secondary dentin through outFormation of secondary dentin through out
life, reduces the size of the pulp chamberlife, reduces the size of the pulp chamber
& root canals& root canals
 Decrease in cellularityDecrease in cellularity
 Odontoblast decrease in size & number, &Odontoblast decrease in size & number, &
may disappear in certain areas. Especiallymay disappear in certain areas. Especially
on pulpal floor over bifurcation &on pulpal floor over bifurcation &
trifurcationtrifurcation

 Increase in number & thickness inIncrease in number & thickness in
collagen fibers particularly in radicularcollagen fibers particularly in radicular
pulppulp
 Reduction in the nerve fibers & bloodReduction in the nerve fibers & blood
vesselsvessels
 Increase resistance of pulp againstIncrease resistance of pulp against
action of enzymesaction of enzymes
 In dentin,In dentin,
Increase in peritulular dentinIncrease in peritulular dentin
Dentinal sclerosis, reducesDentinal sclerosis, reduces
permeabilitypermeability
Increase in dead tractsIncrease in dead tracts

Pulp Fibrosis

CLINICALCLINICAL
CONSIDERATIONSCONSIDERATIONS
► Anatomic considerationsAnatomic considerations
► Effect of dental materials on pulpEffect of dental materials on pulp
► Effect of Operative ProceduresEffect of Operative Procedures
► Effects subsequent to restorationEffects subsequent to restoration

ANATOMICANATOMIC
► Dimensions of tooth preparation are dictated by
pulpal morphology
► Young permanent teeth have wider pulp chamber
and so do deciduous teeth
► Cervical horns present in maxillary molars
complicate class V restoration and endodontic
treatment
► developmental disturbances and advanced age

ANATOMICANATOMIC
Pulp Chamber with stone Cervical hornswww.indiandentalacademy.com

► Factors complicating endodontic treatment
accessory canals curved canals
multiple canals canal morphology
cervical horns apical delta
Chandler et al* conducted a prospective study of the
coronal pulp size & demonstrated the importance of bitewing
radiographs. This study also investigated the effect of
restorations on pulp size and prevalence of pulp stones in
the study group
*International Endodontic journal, 36,757-763.2003

EFFECT OF DENTALEFFECT OF DENTAL
MATERIALS ON PULPMATERIALS ON PULP
► AmalgamAmalgam
corrosion products inhibit cell growthcorrosion products inhibit cell growth
high thermal conductivityhigh thermal conductivity
► Glass ionomersGlass ionomers
well tolerated by pulpwell tolerated by pulp
RMGI used for direct pulp cappingRMGI used for direct pulp capping
► Zinc Oxide EugenolZinc Oxide Eugenol
has an anti-bacterial and anodyne effecthas an anti-bacterial and anodyne effect
higher concentrations leads to chronichigher concentrations leads to chronic
inflammation & thrombosis of vesselsinflammation & thrombosis of vessels

► FormocresolFormocresol
High degree of diffusion causes a chronicHigh degree of diffusion causes a chronic
inflammation of the pulpinflammation of the pulp
Mutagenic and carcinogenicMutagenic and carcinogenic
► Calcium hydroxideCalcium hydroxide
induces dentin bridge formation when used forinduces dentin bridge formation when used for
direct pulp cappingdirect pulp capping
► Mineral trioxide aggregateMineral trioxide aggregate
superior to calcium hydroxide as a direct pulpsuperior to calcium hydroxide as a direct pulp
capping agentcapping agent
dentin bridge formation with minimaldentin bridge formation with minimal
inflammationinflammation

► Zinc PhosphateZinc Phosphate
strong to moderate cyto-toxic reactions is duestrong to moderate cyto-toxic reactions is due
to leeching of zinc ions and low pHto leeching of zinc ions and low pH
► Resin adhesive systemsResin adhesive systems
the formation of hybrid layer secures thethe formation of hybrid layer secures the
enamel-resin interface with a continuousenamel-resin interface with a continuous
seal which acts as a biometic barrierseal which acts as a biometic barrier
Dentin bonding agentsDentin bonding agents
monomer molecules reaching the pulp canmonomer molecules reaching the pulp can
irritate the pulp causing inflammationirritate the pulp causing inflammation
► BleachingBleaching

EFFECT OF OPERATIVEEFFECT OF OPERATIVE
PROCEDURESPROCEDURES
► Effects of tooth preparationEffects of tooth preparation
Frictional heatFrictional heat
DesiccationDesiccation
Exposure of dentinal tubulesExposure of dentinal tubules
Direct damage to odontoblast processDirect damage to odontoblast process
Chemical treatment of exposed dentinalChemical treatment of exposed dentinal
surfacesurface
Lasers- ErYAG, COLasers- ErYAG, CO22 layers better than Ndlayers better than Nd
YAGYAG

► Factors associated with restorativeFactors associated with restorative
material and its placementmaterial and its placement
Material toxicityMaterial toxicity
Insertion proceduresInsertion procedures
Thermal effectsThermal effects
Induced stressesInduced stresses

EFFECTS SUBSEQUENT TOEFFECTS SUBSEQUENT TO
RESTORATIONRESTORATION
► Marginal leakageMarginal leakage
Causes significant pulp irritationCauses significant pulp irritation
Nanoleakage-saliva, bacteria or materialNanoleakage-saliva, bacteria or material
components. Specifically seen in dentin bondingcomponents. Specifically seen in dentin bonding
systems.systems.
► Cuspal flexureCuspal flexure
Dentinal flow & tooth sensitivityDentinal flow & tooth sensitivity
Cuspal & tooth fractureCuspal & tooth fracture

Hi Doc, You are my Cardiologist!www.indiandentalacademy.comwww.indiandentalacademy.com

 Dental pulp; Seltzer &Bender; 3rd
Edn
 Pathways of Pulp; Cohen; 8th
Edn
 Endodontics; Ingle; 5th
Edn
 Endodontic practice; Weine; 5th
&6th
Edn
 Oral Histology; Tencate; 5th
Edn
 Oral Histology & Embryology; Orban; 11th
Edn
 Endodontic Practice; Grossman; 11th
Edn
References

 Colour Atlas of Endodontics; Christopher
Stock
 Colour Atlas of Oral histology; Avery
 Dentin & Pulp In Restorative Dentistry;
Martin Brannstrom
 Practical Endodontics; Edward Benzer
 Restorative material; Craig
 Textbook Of pedodontics; Shobha
Tandon
References

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