dental pulp

Dental PulpDental Pulp

Oral HistologyOral HistologyDent 205Dent 205

Summer semesterSummer semester2005/20062005/2006

Dental pulpDental pulp Dental pulpDental pulp

Crown - pulp chamberCrown - pulp chamber Root - root canal(s)Root - root canal(s)

Dental papilla becomes dental pulp after beginning of Dental papilla becomes dental pulp after beginning of dentinogenesisdentinogenesis

Dental pulp is a specialized connective tissueDental pulp is a specialized connective tissue Positioned inside a rigid chamberPositioned inside a rigid chamber Has a role in forming hard tissueHas a role in forming hard tissue Periphery containsPeriphery contains

Dentine-forming cellsDentine-forming cells Nerve terminalsNerve terminals Antigen-presenting cellsAntigen-presenting cells

The rest of the dental pulp acts as a support system for peripheral The rest of the dental pulp acts as a support system for peripheral componentscomponents

Blood vessels and nerves that enter & leave through an apical foramenBlood vessels and nerves that enter & leave through an apical foramen Cells and collagen fibersCells and collagen fibers

Accessory canalsAccessory canals

Occur most commonly on apical partOccur most commonly on apical part Lateral root canalsLateral root canals Furcation canalsFurcation canals

Composition of dental pulpComposition of dental pulp Loose connective tissueLoose connective tissue ComponentsComponents

CellsCells Extracellular matrixExtracellular matrix

FibersFibers Non-fibrous matrix - Semi-fluid gelNon-fibrous matrix - Semi-fluid gel

Matrix more plentiful than cellsMatrix more plentiful than cells Functions of the matrixFunctions of the matrix

Forms a scaffold that stabilizes the structure of the Forms a scaffold that stabilizes the structure of the tissuetissue

Controls cellular activityControls cellular activity

FibersFibers CollagenCollagen

Type I (56%)Type I (56%) Thin & scattered in young teethThin & scattered in young teeth Irregular arrangementIrregular arrangement Near predentine, fibers are regularly arranges parallel to predentine Near predentine, fibers are regularly arranges parallel to predentine

surfacesurface Type III (41%)Type III (41%) Types V & VITypes V & VI

FibrillinFibrillin Large glycoproteinsLarge glycoproteins Associated with elastic fibers in other tissuesAssociated with elastic fibers in other tissues Elastic fibers are absentElastic fibers are absent

Non-fibrous matrixNon-fibrous matrix GlycosaminoglycansGlycosaminoglycans

HydrophilicHydrophilic Swell when hydrated accounting for Swell when hydrated accounting for

High pressure in the dental pulpHigh pressure in the dental pulp Mechanical supportMechanical support Easy movement of water-soluble moleculesEasy movement of water-soluble molecules

TypesTypes Chondroiten sulphate - predominentChondroiten sulphate - predominent Dermatan sulphate – small amountsDermatan sulphate – small amounts Heparan sulphateHeparan sulphate Hyaluronan sulphate – mostly unbound to proteinsHyaluronan sulphate – mostly unbound to proteins

ProteoglycansProteoglycans Act as adhesion molecules bound to cell membranes and bind signaling molecules like GFsAct as adhesion molecules bound to cell membranes and bind signaling molecules like GFs

Other adhesion moleculesOther adhesion molecules Fibronectin that regulates cell shape, migration & differentiationFibronectin that regulates cell shape, migration & differentiation Lamenin Lamenin

Around endothelial cells of blood vessels & Schwann cellsAround endothelial cells of blood vessels & Schwann cells Coating cell bodies and processes of odontoblastsCoating cell bodies and processes of odontoblasts

CellsCells OdontoblastsOdontoblasts FibroblastsFibroblasts Defence cellsDefence cells Undifferentiated cellsUndifferentiated cells

OdontoblastsOdontoblasts Formation of dentineFormation of dentine Survive for as long as the tooth is vitalSurvive for as long as the tooth is vital Odontoblasts cannot divide but subodontoblasts canOdontoblasts cannot divide but subodontoblasts can Polarized columnar cells with processes extending within a tubulePolarized columnar cells with processes extending within a tubule In root region, cells are more cuboidalIn root region, cells are more cuboidal Odontoblastic cell layer hasOdontoblastic cell layer has

A membrane-like propertiesA membrane-like properties Acts as a barrier to protect the dental pulp from outside irritantsActs as a barrier to protect the dental pulp from outside irritants A limited permeability due toA limited permeability due to

DesmosomesDesmosomes Tight junctionsTight junctions Gap junctionsGap junctions

FibroblastsFibroblasts Linked by adherense type junctions & gap Linked by adherense type junctions & gap

junctionsjunctions Stellate cells with star-like extensionsStellate cells with star-like extensions Undergo cell divisionUndergo cell division FunctionsFunctions

Production of fibers & ground substance and Production of fibers & ground substance and participate in their degradationparticipate in their degradation

May produce bone-like mineralized tissue as a May produce bone-like mineralized tissue as a response to pulpal injuryresponse to pulpal injury

Production of GFs and cytokinesProduction of GFs and cytokines

Defence cellsDefence cells

T-lymphocytesT-lymphocytes In small amountsIn small amounts Increase in pulpal injuriesIncrease in pulpal injuries

Macrophages & antigen-presenting cellsMacrophages & antigen-presenting cells Around blood vesselsAround blood vessels Around the odontoblastic layerAround the odontoblastic layer

Mast cells are absentMast cells are absent

Undifferentiated cellsUndifferentiated cells

Primitive mesenchymal cellsPrimitive mesenchymal cells Differentiate into odontoblats to produce Differentiate into odontoblats to produce

tertiary dentinetertiary dentine

Blood vesselsBlood vessels Run longitudinally through root canals from the apical Run longitudinally through root canals from the apical

foramenaforamena Gives off side branches while within the canalsGives off side branches while within the canals Branch profusely once they reach the pulp chamberBranch profusely once they reach the pulp chamber Capillary loops extend towards the dentineCapillary loops extend towards the dentine Subodontoblastic capillary plexusSubodontoblastic capillary plexus Capillaries are present within & below the odontoblastic layer Capillaries are present within & below the odontoblastic layer

but do not enter the tubulesbut do not enter the tubules Arteriovenous and venous-venous anastomosisArteriovenous and venous-venous anastomosis Lymphatic vessels are hard to destinguishLymphatic vessels are hard to destinguish Nerve endings are associated with smooth muscles of arteriole Nerve endings are associated with smooth muscles of arteriole

wallswalls Pulp has a high pulsatile interstitial fluid pressure which Pulp has a high pulsatile interstitial fluid pressure which

allows dentinal fluids to move outwardsallows dentinal fluids to move outwards

NervesNerves

Dental pulp is highly innervatedDental pulp is highly innervated Scant perineurium or epineuriumScant perineurium or epineurium Two types of nerve fibersTwo types of nerve fibers

25% are myelinated afferents25% are myelinated afferents 90% of which are narrow A90% of which are narrow Aδδ fibers fibers 10% are wider A10% are wider Aββ fibers fibers

Unmyelinated C fibersUnmyelinated C fibers Afferents orAfferents or AutonomicAutonomic

NervesNerves

Run along side the blood vessels in the center of the Run along side the blood vessels in the center of the pulppulp

Branch profusely in the odontoblastic & Branch profusely in the odontoblastic & subodontoblastic regionssubodontoblastic regions

In the crown, subodontoblastic plexus is known as In the crown, subodontoblastic plexus is known as plexus of Raschkowplexus of Raschkow Evident only after eruptionEvident only after eruption Some branches reach between odontoblasts & predentineSome branches reach between odontoblasts & predentine Others continue & join the processes within the tubulesOthers continue & join the processes within the tubules May be a site of sensory activation as evident because May be a site of sensory activation as evident because

axons lack Schwann cell coveringaxons lack Schwann cell covering

Nerve fiber typesNerve fiber types Myelinated afferents – carry sensation of sharp pain to CNSMyelinated afferents – carry sensation of sharp pain to CNS

AAδδ fibers fibers AAββ fibers fibers

Unmyelinated C fibersUnmyelinated C fibers AfferentsAfferents

Conduction of noxious stimuli to CNSConduction of noxious stimuli to CNS Axon reflexes to control blood flowAxon reflexes to control blood flow

AutonomicAutonomic Sympathetic fibers supply the smooth muscles of arteriolic wallsSympathetic fibers supply the smooth muscles of arteriolic walls Evidence of parasympathetic supply is weakEvidence of parasympathetic supply is weak

*Some pulpal fibers may have a role in controlling the activity of *Some pulpal fibers may have a role in controlling the activity of odontoblastsodontoblasts

Nerve endingsNerve endings

Some Some AAδδ fibers enter the tubules in the coronal fibers enter the tubules in the coronal dentinedentine

Others end in predentine –pulp junctionOthers end in predentine –pulp junction It is suggested that there is a specialized It is suggested that there is a specialized

junction between nerve endings & junction between nerve endings & odontoblastsodontoblasts

RegionsRegions Supraodontoblastic regionSupraodontoblastic region

Not present in vital pulpsNot present in vital pulps Due to shrinkage of pulpal tissue during perparationDue to shrinkage of pulpal tissue during perparation Two structures are presentTwo structures are present

Unsheathed axonsUnsheathed axons Dendritic antigen-presenting cellsDendritic antigen-presenting cells

Odontoblastic layerOdontoblastic layer Subodontoblastic zoneSubodontoblastic zone

Cell-free zone of WeilCell-free zone of Weil No cells are evidentNo cells are evident Only axons & cell processes of fibroblasts & other cellsOnly axons & cell processes of fibroblasts & other cells Usually absent in radicular pulpUsually absent in radicular pulp

Cell-rich zoneCell-rich zone Appears in contrast to cell-free zoneAppears in contrast to cell-free zone Capillaries and nerve plexuses that contain the cell bodies of Schwann cells, endothelial cells, Capillaries and nerve plexuses that contain the cell bodies of Schwann cells, endothelial cells,

etc.etc.

Central regionCentral region The bulk of the dental pulpThe bulk of the dental pulp Central neurovascular coreCentral neurovascular core Fibroblasts, defence cells, undifferentiated cellsFibroblasts, defence cells, undifferentiated cells Collagenous matrix and ground substanceCollagenous matrix and ground substance

RegionsRegions

Age-related changesAge-related changes Getting smallerGetting smaller Reduction in vascular, neural & Reduction in vascular, neural &

cellular contentscellular contents Increase in fibrous matrixIncrease in fibrous matrix Some degree of mineralizationSome degree of mineralization

Pulp stonesPulp stones Single vs. groupsSingle vs. groups True (dentine-like that may be True (dentine-like that may be

lamellated) vs. false (bone-like)lamellated) vs. false (bone-like) Free vs. attachedFree vs. attached

Snow storm calcificationSnow storm calcification Tiny spicules throughout the pulpTiny spicules throughout the pulp