pulpal dental pain . oral physio lec 2

8/3/2019 Pulpal Dental Pain . oral physio lec 2

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PULPAL & DENTALPULPAL & DENTAL

PAINPAIN

Oral physiologyOral physiology

Dent 207Dent 207


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Dental pulpDental pulp

Specialized connective tissueSpecialized connective tissue

Contained within the toothContained within the tooth

Enclosed by dentineEnclosed by dentine

Continuous with the periodontal ligament through:Continuous with the periodontal ligament through:

Apical foramenApical foramen

NarrowNarrow only allows for passage of the neurovascularonly allows for passage of the neurovascularbundlebundle

Small volumeSmall volume

Total volume in all teeth is 0.40 mlTotal volume in all teeth is 0.40 ml


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Pulpodentine complexPulpodentine complex

Functions of pulp & dentine are interlinkedFunctions of pulp & dentine are interlinked

Functions of the pulpFunctions of the pulp

Maintain dentinal health by supplying nutrientsMaintain dentinal health by supplying nutrients Provide a pathway for sensory impulses fromProvide a pathway for sensory impulses from

dentinedentine

Initiate & govern repair of dentine in injuryInitiate & govern repair of dentine in injury


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Pulp nervesPulp nerves

Sensory fibersSensory fibers

AA & C fibers& C fibers

Plexus of Raschkow (subodontoblastic plexus)Plexus of Raschkow (subodontoblastic plexus) Individual axons divide into many branches in theIndividual axons divide into many branches in the

plexusplexus


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Pulp nerves during tooth formationPulp nerves during tooth formation

Fibers near base of dental papillaFibers near base of dental papilla

At cap stageAt cap stage Fibers form a plexusFibers form a plexus -- to dental follicleto dental follicle to dental papillato dental papilla

At bell stageAt bell stage unmyelinatedunmyelinated

At eruptionAt eruption -- number of fibers & their average size increasenumber of fibers & their average size increase --transition towards myelinationtransition towards myelination

Continues to increase for a few years after eruptionContinues to increase for a few years after eruption

Dentine is laid downDentine is laid down pulp reduced in sizepulp reduced in size nerve plexusnerve plexusdecrease in sizedecrease in size

Ageing pulpAgeing pulp Decrease in number of axons entering pulpDecrease in number of axons entering pulp

Reduction in myelinated fiber sizeReduction in myelinated fiber size

Raschkows shows little changeRaschkows shows little change


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Pulp nerves in primary teethPulp nerves in primary teeth

Number of axons is less than that in permanentNumber of axons is less than that in permanent

Except primary canineExcept primary canine

Number of axons decrease with resorptionNumber of axons decrease with resorptionuntil the tooth is sheduntil the tooth is shed


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Neurotrophic substancesNeurotrophic substances

Nerve growth factorsNerve growth factors evidenceevidence Promote survival of neural crest cells in trigeminalPromote survival of neural crest cells in trigeminal

ganglionganglion

Produced in the maxillary process to maintain survival ofProduced in the maxillary process to maintain survival of

nerve axonsnerve axons No role in directing spread of fibersNo role in directing spread of fibers

Act on nearby nerves to govern late invasion of pulp tissueAct on nearby nerves to govern late invasion of pulp tissueby nerve fibersby nerve fibers

Allow permanent teeth to recruit their nerve supply fromAllow permanent teeth to recruit their nerve supply from

branches of axons previously supplying deciduous teethbranches of axons previously supplying deciduous teeth Odontoblastic factors promote extension of new nerveOdontoblastic factors promote extension of new nerve

fibers into the subodontoblastic layer & dentine infibers into the subodontoblastic layer & dentine inreimplanted teethreimplanted teeth


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Functions of AFunctions of A fibersfibers

MyelinatedMyelinated

Diameter: 1Diameter: 1 4 m4 m

Rapidly conducting (>2 m/s)Rapidly conducting (>2 m/s)

Mediate sharp, piercing pain sensationsMediate sharp, piercing pain sensations

Responsible for dentinal sensitivityResponsible for dentinal sensitivity

Respond to any stimuli causing fluid movement inRespond to any stimuli causing fluid movement in

dentinal tubulesdentinal tubules Drilling, drying & application of osmotic solutionsDrilling, drying & application of osmotic solutions


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Functions of C fibersFunctions of C fibers

UnmyelinatedUnmyelinated

Diameter: < 0.5 mDiameter: < 0.5 m

Slowly conducting (< 2 m/s)Slowly conducting (< 2 m/s) Polymodal: activated byPolymodal: activated by

ThermalThermal

MechanicalMechanical

Chemical stimuliChemical stimuli histamine & bradykinenhistamine & bradykinen

Mediate dull, longer standing & less wellMediate dull, longer standing & less well--localizedlocalized


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Neurotransmitters in dental pulpNeurotransmitters in dental pulp

Calcitonin geneCalcitonin gene--related peptide (CGRP)related peptide (CGRP)

Substance PSubstance P

Neurokinin ANeurokinin A


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Autonomic nerve supply in the pulpAutonomic nerve supply in the pulp

SympatheticSympathetic

ParasympatheticParasympathetic


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SympatheticSympathetic

Majority of autonomicMajority of autonomic

Some are cholinergicSome are cholinergic Removal of superior cervical ganglionRemoval of superior cervical ganglion some decrease insome decrease in

cholinesterase staining in the pulpcholinesterase staining in the pulp

In mouseIn mouse in pulp horn in pulp horn

1/3 in pulp chamber1/3 in pulp chamber

Rest in root canalRest in root canal

FunctionsFunctions

Control pulp blood flowControl pulp blood flow Regulation of odontogenesisRegulation of odontogenesis

Afferent transmission of impulses associated with pain sensationAfferent transmission of impulses associated with pain sensation

Evidences of functionsEvidences of functions Anatomical: near blood vessels & odontoblastsAnatomical: near blood vessels & odontoblasts

SympathectomySympathectomy vasodilatation & changed in dentine appositionvasodilatation & changed in dentine apposition


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ParasympatheticParasympathetic

Majority are cholinergicMajority are cholinergic

Resection of inferior alveolar nerveResection of inferior alveolar nerve

Abolish cholinesterase stainingAbolish cholinesterase staining

Increased rate f tooth eruption (increased intrapulpalIncreased rate f tooth eruption (increased intrapulpal

pressure)pressure)


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Nociceptive responseNociceptive response substance Psubstance P

Pulp reacts initially to stimulating dentinePulp reacts initially to stimulating dentine

ElectricallyElectrically

MechanicallyMechanically

ChemicallyChemically C fibers stimulatedC fibers stimulated --

Retrograde impulse in C branchesRetrograde impulse in C branches

Release of substance P at terminalsRelease of substance P at terminals

VasodilatationVasodilatation tissue edematissue edema

Release of histamineRelease of histamine increase capillary permeability &increase capillary permeability &fluid extravasationfluid extravasation


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Nociceptive responseNociceptive response -- bradykininbradykinin

Noxious stimulation of the pulpNoxious stimulation of the pulp

Bradykinin formationBradykinin formation

Contribute to vasodilatationContribute to vasodilatation May stimulate release of encephalins from pulpalMay stimulate release of encephalins from pulpal

cellscells

EncephalinsEncephalins antianti--inflammatoryinflammatory inhibitinhibit

bradykinin releasebradykinin release protectiveprotective ve feedbackve feedback

mechanismmechanism


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Nociceptive responceNociceptive responce ecosanoidecosanoid

groupgroup Are metabolites of arachidonic aidAre metabolites of arachidonic aid

ProstaglandinsProstaglandins

LeucotrienesLeucotrienes

PG I2 produced by endothelial cellsPG I2 produced by endothelial cells

Inhibit platelet aggregationInhibit platelet aggregation

VasodilatorVasodilator

Thromboxane A2 produced by platelets & fibroblastsThromboxane A2 produced by platelets & fibroblasts

Stimulate platelet aggregationStimulate platelet aggregation

In the pulpIn the pulp PGPG II22, PG, PG FF22 , PG, PG EE22 ThromboxaneThromboxane AA22 Leucotrience 12Leucotrience 12--HETE, LTCHETE, LTC44


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Nociceptive responseNociceptive response prostaglandinsprostaglandins

Bacterial/mechanical/chemical irritationBacterial/mechanical/chemical irritation

Increase in prostaglandinIncrease in prostaglandin FF22 && EE22 (found in high(found in high

conc. In inflamed pulp)conc. In inflamed pulp) VasodilatationVasodilatation

Increase painIncrease pain--producing properties ofproducing properties of

HistamineHistamine

BradykininBradykinin

SerotoninSerotonin


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Pain relieving drugsPain relieving drugs

AspirinAspirin inhibitor of cycloinhibitor of cyclo--oxygenaseoxygenase

inhibition of PG synthesisinhibition of PG synthesis

Root canal medicamentsRoot canal medicaments Phenol, pPhenol, p--Chlorophenol, cresol, thymol, guaiacolChlorophenol, cresol, thymol, guaiacol

Inhibit synthesis of PG & leucotrienesInhibit synthesis of PG & leucotrienes

Have antibacterial activityHave antibacterial activity

EugenolEugenol more effective than phenols inmore effective than phenols in

inhibition of prostaglandin synthesisinhibition of prostaglandin synthesis


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Pulpitis & pulp necrosisPulpitis & pulp necrosis

Injury to dentine (cavity prep.)Injury to dentine (cavity prep.)

Nerve fibers & odontoblastic processes pulled byNerve fibers & odontoblastic processes pulled by

hydrodynamic forcehydrodynamic force

Separated from pulpal tissueSeparated from pulpal tissue

Damaging nerve fibers & killing of odontoblastsDamaging nerve fibers & killing of odontoblasts

Pain in dentinePain in dentine


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Small injury to dental pulpSmall injury to dental pulp

In small damaged areas / odontoblastic layerIn small damaged areas / odontoblastic layer

damage is slightdamage is slight

Reparative dentine may seal off small damagedReparative dentine may seal off small damagedareasareas

Blocks reBlocks re--innervationinnervation

Innervation of adjacent areas is increasedInnervation of adjacent areas is increased

CGRP from reactive axons promote growth of newCGRP from reactive axons promote growth of newfibersfibers

When the lesion healsWhen the lesion heals -- new fibers disappearnew fibers disappear


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PulpitisPulpitis

Cavity or caries reach the pulpCavity or caries reach the pulp Odontoblastic layer destroyedOdontoblastic layer destroyed

Inflammation occurs locallyInflammation occurs locally

In small lesions, dentine bridge formsIn small lesions, dentine bridge forms inflammationinflammationresolves & pulp heals (reversible pulpitis)resolves & pulp heals (reversible pulpitis) Inflammation area demarcated by fibrous tissueInflammation area demarcated by fibrous tissue

More severe stimuli / larger lesionsMore severe stimuli / larger lesions irreversible pulpitisirreversible pulpitis Severe inflammationSevere inflammation --inflammation area demarcated by fibrousinflammation area demarcated by fibrous

tissuetissue

Lack of pain at a later stage of pulpitisLack of pain at a later stage of pulpitis CGRPCGRP--mediated growth of nerve fibers outsidemediated growth of nerve fibers outside

inflammation areainflammation area Hypersensitivity in early pulpitisHypersensitivity in early pulpitis

Difficulty in achieving anesthesia a tooth with an inflamed pulpDifficulty in achieving anesthesia a tooth with an inflamed pulp


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Pulp necrosisPulp necrosis

More severe pulpal exposureMore severe pulpal exposure

Irreversible pulpitisIrreversible pulpitis -- necrosis occursnecrosis occurs

Necrosis area demarcated by fibrous tissueNecrosis area demarcated by fibrous tissue CGRPCGRP--mediated growth of nerve fibers outsidemediated growth of nerve fibers outside

necrosis areanecrosis area

Lesion extends to root apexLesion extends to root apex

Nerve growth in periapical tissueNerve growth in periapical tissue

New fibers appear to be involved in pain sensationNew fibers appear to be involved in pain sensation


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Pain of dental originPain of dental origin

Exposed dentineExposed dentine sensitivitysensitivity -- painpain Dental caries or cavity prep.Dental caries or cavity prep.

Cemental layer wears awayCemental layer wears away

Any sensation through dentineAny sensation through dentine painpain

Heat / cold may be perceived as separate sensations?Heat / cold may be perceived as separate sensations? Most sensitive areas in dentine as atMost sensitive areas in dentine as at

EDJEDJ

Exposed dentine in cervical root areasExposed dentine in cervical root areas

Nerve fibers to dentine are limited to coronal dentineNerve fibers to dentine are limited to coronal dentine

Nerve fibers numerous under cuspsNerve fibers numerous under cusps Nerve fibers extend for a short distance within dentineNerve fibers extend for a short distance within dentine

Odontoblastic processes vary in extension through dentineOdontoblastic processes vary in extension through dentine Function as receptorsFunction as receptors


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Three theories of dentinalThree theories of dentinal

hypersensitivityhypersensitivity

Odontoblastic processes as receptorsOdontoblastic processes as receptors

Odontoblasts are neural crest in originOdontoblasts are neural crest in origin

Nerve fibers extend through dentineNerve fibers extend through dentine

Direct stimulationDirect stimulation Deformation of odontoblasts by fluid movement promotesDeformation of odontoblasts by fluid movement promotes

potassium releasepotassium release action potential in neighboring nerveaction potential in neighboring nervefibersfibers

Hydrodynamic theoryHydrodynamic theory Movement of fluids through dentinal tubules inward &Movement of fluids through dentinal tubules inward &outwardoutward

Distortion of nerve endings in Raschkows plexusDistortion of nerve endings in Raschkows plexus


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Referred painReferred pain

Sensation of pain resulting from a deep organSensation of pain resulting from a deep organ

peripherally in areas derived from the sameperipherally in areas derived from the same

somitesomite

Pain of cardiac origin may be perceived in the armPain of cardiac origin may be perceived in the arm

Convergence of somatic & visceral sensoryConvergence of somatic & visceral sensory

impulses at one or more of 3 levelsimpulses at one or more of 3 levels

PrespinalPrespinal

SpinalSpinal

SupraspinalSupraspinal


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Referred orofacial painReferred orofacial pain

In trigeminal, levels areIn trigeminal, levels are PrepontinePrepontine

PontomedullaryPontomedullary

SuprapontineSuprapontine

No convergence within brainNo convergence within brain

Pain within the oral cavity is referredPain within the oral cavity is referred

Within the distribution of the specific divisions of the trigeminal nerveWithin the distribution of the specific divisions of the trigeminal nerve

Doesnt cross midline except in ramifications of nerve terminalsDoesnt cross midline except in ramifications of nerve terminals(incisor region)(incisor region)

Migrainous headache may be due to dental conditionsMigrainous headache may be due to dental conditions Not referred painNot referred pain

Because it is vascular in originBecause it is vascular in origin

pulpal dental pain . oral physio lec 2

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