intro to dental pain
TRANSCRIPT
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 1/9
Dental Pain
Aims & Objectives
Aim - To introduce theories of pain and pulpal
sensitivity Objectives - By the end of the lecture you should be
able to: Outline the embryology of the dental pulp
Describe the theories of dentinal sensitivity with reference toanatomy of the pulp
See the relevance of the hydrodynamic theory to operative
dentistry
Suggest what modifies perception of pain
Determine which nerves are being stimulated causing dentalpain
Pain
an unpleasant and emotionalexperience associated with actual orpotential tissue damage or described interms of such damage
Presentation of pain
Can you see it?
Organic damage
Psychological damage
Interaction of these
Trauma (eg. hot/cold, physical)
Pain
Misdirection:
Focussed activity/Hypnosis
Reducing factors
Concentration:
Expectation/ Anxiety
Increasing factors
TENS
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 2/9
Where does the dental pulpcome from? Layers
Ectoderm
Mesoderm
Endoderm
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 3/9
Gut
NeuralTube
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 4/9
The dentine-pulp complex
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 5/9
Theories of dentinal sensitivity
Innervation of tubules
Synaptic junction with odontoblast
Hydrodynamic theory
Nerve fibrils are in the tubulesTheory 1
Theories of dentinal sensitivity
Innervation of tubules
Synaptic junction with odontoblast
Hydrodynamic theory
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 6/9
Anastamosis with odontoblastTheory 2
Theories of dentinal sensitivity
Innervation of tubules
Synaptic junction with odontoblast
Hydrodynamic theory
Hydrodynamic theory
Gysi 1900
Brännström et al 1967
Cold – outward flow: aspiration & lessshearing forces
Hot – inward flow
Alfred E Gysi
1865-1957
Fluid movement in tubulesTheory 3
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 7/9
Nerves
A-β
A-δ myelinated
C (0.2-1.0μm) respond to mediators of inflammation)
Mechanism of dentinal fluid flow
Fluid outflow
Increased byinflammation/neuropeptides
Decreased by
Albumin, globulins, fibrinogen
Fluid flow and pain
18.1 pLs-1mm-2
Normal physiological flow
1.0-1.5 nLs-1mm-2
Threshold for pain sensation (50x normal)
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 8/9
Sensation from the pulp
Few proprioceptive fibres – body finds it
difficult to localise Hot/cold/tingle
Pain or no pain
Fluid flow in teeth
Poiseuille-Hagen equation
V = π ΔP r4
8η l
V= volumeP= pulpal pressure
r = tubule radiusl = tubule length
η= viscosity of fluid
Pashley (1989) Scanning Microsc 3 161-176
Pulpal Pressure
Increased in inflammation
Decreased with local containingadrenaline
Tubule morphology
Pulpenamel 0.8μm 3μm
Fluid flow in teeth
Tubule radius0.8 - 2.5µm (EDJ - pulp)
(anatomical. Functional diameter5-10%)
Pulpal pressure
15cm H2O - 36cm H2O (low-high)
Fluid viscosity
Decreases from pulp to EDJ
Michelich et al (1978) J Dent Res 57 1019-1024Gerzina and Hume (1995) J Dent Res 74 369-373
8/4/2019 Intro to Dental Pain
http://slidepdf.com/reader/full/intro-to-dental-pain 9/9
Cavity ½ dentine depth
If we assume viscosity and pulpal
pressure remain constant relative tofluid flow at EDJ :
Radius increases x16
Length of tubule x0.5
Fluid flow increases x32
Cavity ¾ dentine depth
If we assume viscosity and pulpal
pressure remain constant relative tofluid flow at EDJ:
Radius increases x256
Length of tubule x0.25
Fluid flow increases x1024
Tubules
Density varies between and within teeth
≈ 75,000 mm-2 coronally
≈ 30,000 mm-2 mid-root
Surface area of dentine made up of tubules
1% at EDJ
22% at pulp
Schellenberg et al (1992) J Endod 18 104-109
Pashley (1989) Scanning Microsc 3 161-176