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Pulpal disease > Dentine sensitivity > Flashcards

Dentine sensitivity Flashcards

1
Q

Pain producing stimuli - intact tooth

A

Thermal (enamel conducts)

  • heating 45 C
  • cooling 27 C
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2
Q

Thermal stimuli reaction times

A

Nerves stimulated before any T change in pulp
-receptor: detection
Reaction times < by pre-warming and > by pre-cooling tooth for cold stimulus

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3
Q

Pain producing stimuli: enamel removed

A 
Mechanical stimuli
Drying 
-air
-responds to dry absorbent paper
Hydrostatic pressure
Thermal stimuli
Chemical stimuli
-dentine sensitive throughout thickness
-not all stimuli may result in pain in man
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4
Q

Chemical stimuli producing pain in dentine

A

Algesic substances: bradykinin, histamine, no pain
Conc. sugar solns, related to osmotic p, pain
Topical application of local anaesthetic, no effect on dentine sensitivity

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5
Q

Nerves in pulp: neuroanatomy

A

Pulp richly innervated
->900 fibres enter apex of human premolars
-extensive branching of fibres into smaller axons, terminate as free nerve endings (no specific receptors such as found in skin)
Structure similar in man, monkeys, dogs and cats

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6
Q

Which nerves are present in pulp?

A

Myelinated and unmyelinated axons present

A delta, A beta and C fibres

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7
Q

Conduction velocity of nerves in pulp

A

Within pulp itself: (A delta and C): 1-34m/s

Outside pulp chamber (A beta, A delta and C fibres): 1-58m/s

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8
Q

Where are A beta fibres found?

A

Outside pulp chamber, can extend into pulp but conduction velocity decreases with < in diameter

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9
Q

Changes in diameter of nerves in pulp

A

Smaller in diameter near terminals

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10
Q

Dentinal tubule contents

A

Inner dentine (innervated)
-odontoblast cell process
-smaller process (nerve?)
-100-200µm
-one pulpal axon may innervate 100 dentine tubules; v high density of free nerve endings
Outer dentine: odontoblast cell process?, but not small process
-not innervated but v sensitive

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11
Q

Denervation studies

A

2 days after nerve section small processes disappear
12 weeks after nerve section small processes return
Correlation of return of responses of intradental nerves to dentine stimulation

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12
Q

Axonal transport studies

A

Tritiated proline, injected into trigeminal ganglion, transported along nerves into pulps of teeth and inner dentine
Distribution of lavelled material similar to distribution of secondary processes

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13
Q

Role of odontoblast layer in intradental nerve responses

A

TEM shows tight junctions between odontoblasts and some terminal axons
Attempts to measure resting membrane potential of odontoblasts show values too low to act as receptor
Pain still felt after odontoblasts have been damaged

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14
Q

Responses of intradental nerves to stimulation

A

Recordings from single pulpal axons demonstrated:

  • stimuli that produce pain in man excite intradental nerve
  • 2 classes of neurones identified
  • smear layer affects response
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15
Q

Classes of intradental afferent neurones

A
  1. Cold sensitive neurones

2. Heat sensitive neurones

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16
Q

Cold sensitive neurones

A

Short latency response to cooling, also respond to drying, mechanical stimulation of exposed dentine, high conc. solns and pressure changes, also respond to heat
Conduction velocity upper part of range for intradental nerves, including A beta fibres

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17
Q

Heat sensitive neurones

A

Longer latency response to heating, rarely respond to other forms of stimuli
Conduction velocity lower part of range for intradental nerves

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18
Q

Effect of smear layer

A

Enhanced response after acid etching, affected by dentine permeability

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19
Q

Hydrodynamic theory: Braennstroem 1963

A

Fluid movement in tubules leads to mechanical distortion of tissue
Most likely mechanism for dentine sensitivity
Some chemical stimuli are isotonic

20
Q

All stimuli that cause pain

A

Except electrical

Can produce fluid movement through tubules

21
Q

A-unit activation

A

Cold sensitive
Probably hydrodynamic effects
i.e. displacement of tubule contents leads to activation of cold sensitive neurones

22
Q

C-fibres

A

Heat sensitive
Do not respond to stimuli producing fluid movement
Are sensitive to direct heating (longer latency)

23
Q

Summary: sensitivity mechanism

A

Displacement of tubule contents leads to activation of cold sensitive neurones
Heat sensitive neurones sensitive to direct heating
‘Receptors’ for both classes situated in inner dentine or outer pulp
Role of odontoblast in receptor mechanism

24
Q

Dentine hypersensitivity

A

Exaggerated, trnasient response
Affects up to 57% population
No pathology or dental defect

25
Q

Dentine hypersensitivity: aetiology

A

Enamel erosion
Whitening
Recession
Viability of cementum

26
Q

Dentine hypersensitivity affected by

A

surface permeability

rapid response

27
Q

Treatment of dentine hypersensitivity mechanisms

A
  1. Reducing dentine permeability (<1µm + no.)

2. Altering ionic environment in tubules

28
Q

Treaments of dentine sensitivity

A 
Management
Desensitising toothpastes
Adhesive resins
Tannic acid 
Lasers
Ozone treatment
29
Q

Desensitising toothpastes

A

Arginine
Stannous fluoride
Bioglass

30
Q

Adhesive resins

A

Dentine bonding resins - seal dentine surface

  • not fluoride
  • limited evidence
31
Q

Tannic acid

A

Blocks tubuels

32
Q

Lasers

A

Fuse tubules by coagulatin proteins

-limited evidence

33
Q

Ozone treatment

A

Removes pellicle and allows remineralisation

34
Q

Injury to the pulp

A

Mechanical damage: dislocation of odontoblasts
-dentine does not lose sensitivity
-innervation of dentine not prerequisite for sensitivity
Chemical attack:
-osmotic stimulants produce dislocation: mediated by tubule fluid movement
-direct toxicity: acids and neurotoxins

35
Q

Correlation between pulp pathology and pain sensations

A

None

Vasodilation, immune cells, odontoblast distortion

36
Q

Neuropeptides and toxins released locally

A

Substance P, CGRP, VIP (neuropeptides)
Neurokinins, cytokines (bradykinin, histamine)
Link with microvascular blood flow

37
Q

Biochemical markers

A

More subtle indicators or pain

38
Q

Coronal injury

A

Aspiration of odontoblasts

Nerves survive operative procedures and placement of materials

39
Q

Cervical injury

A

Calcitonin gene-related peptide (CGRP) fibres proliferate after cervical injury
Relates to developing sensitivity after injury

40
Q

Severe pulpal injury: local pulpitis

A

Large areas of SP and CGRP containing fibres sprout near injury site
Tertiary dentine forms

41
Q

Severe pulpal injury: irreversible pulpitis (Necrosis)

A

CGRP and sprouting at interface between vital and non-vital tissue

42
Q

Severe pulpal injury

A

Nerve fibres proliferate:
-odontoblasts distorted, nerve strectched and stimulated (No correlation with pain and nerve density)
-odontoblasts release NGF on stimulation (6 hours after cavity prep)
Nerves have other functions than pain in tooth pulp: role in pulpal healing, chemotactant, protective

43
Q

Caries and pain

A

Nerve trunk increase in SP and CGRP expression

44
Q

Spontaneous pulpitic pain

A

High levels of SP and VIP

45
Q

Use of peptide antagonists

A

To control pulpal inflammation and pain

46
Q

Calcium oxalate

A

closes tubules by remineralisation

-limited/ insufficient evidence

47
Q

Management of dentine hypersenstivity

A

Reduction of erosive dietary intake

Gentle brushing

Pulpal disease (11 decks)

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