bds2 pulp morphology and biology Flashcards
list the components of the dental pulp
connective tissue
cells:
- odontoblasts
- fibroblasts
- defence cells
extracellular components
- collagen and oxytalan fibres
- matrix composed of proteoglycans, chondroitin sulphate and derma tan sulphate
nerves
- sensory
- sympathetic
blood vessels and lymphatics
functions of the dental pulp
nutrition via blood vessels
dentine growth
dentine repair
defence via immune cells and lymphatics
neural via sensory and control of dentinogenesis
which pulpal elements extend into the dentine
odontoblast process
nerve terminals
immune cells
dentinal fluids
describe the haemodynamics and hydrodynamics of the pulp
fluid leaks form the pulp capillaries to the interstitial space
some drain via lymphatics and some pass along the dentinal tubules
what are the functional links between dentine and pulp
formation of secondary dentine
formation of tertiary dentine in response to tooth wear including reactionary and reparative dentine
regulate exchange of material between dentine and pulp
what are the causes of tooth wear for enamel and dentine
mastication
bruxism
abfraction
diet
caries
operative procedures
what type of wear is mastication
abrasion
what type of wear is bruxism
attrition
what is abfraction
occlusal overload leading to fractures and cervical lesions
what are operative procedures that can lead to tooth wear
occlusal equilibration
cavity cutting and crown preparation
what is reactionary dentine
tertiary dentine formed in response to mild stimulus and laid down by primary odontoblasts
what is reparative dentine
tertiary dentine formed in response to intense stimulus that destroys the primary odontoblasts
laid down by secondary odontoblasts
what is the function of the odontoblast layer of the pulp periphery
separate the pulp and the tubular space
regulate the movement of material between pulp and tubular extracellular fluid
explain the material exchanged from the pulp to the dentine
nutrients to sustain cells
formation of secondary and tertiary dentine
function of tubular nerves eg potassium ions
explain the material exchanged from the dentine to the pulp
medicaments applied to dentine
diffusion of toxins from bacteria and components of filling materials
describe the anatomy of pulp nerves
branches of alveolar nerves
neuromuscular bundles enter the pulp via the apical foramen and pass along the root canal in the centre of pulp toward coronal pulp chamber
the branches then fan out in the sub odontoblastic layer to form raschows plexus
the terminal branches enter the odontoblast layer and some nerves will enter the dentinal tubules
what is raschows plexus
when nerves enter the pulp via the apical foramen and branch out in the subodontoblastic layer, this plexus is formed
describe the innervation of the dental tubules
some nerves can enter the tubules but not all
under the cusps, 40% of tubules have nerves
tubular innervation is less in coronal dentine and root dentine
how innervated is coronal dentine
15%
how innervated is root dentine
4%
where do most axons end in the dentine pulp complex
pulp-predestine region
describe the hydrodynamic mechanism for activating intradental sensory nerves
stimulus acts on exposed dentine with open tubules which increases the rate of dentinal fluid flow
this generates action potential in intradental nerves
these action potentials pass to the brain to cause pain
what are the effects of outward dentinal fluid flow
drying
evaporation
hypertonic solutions
decreased hydrostatic pressure
what are the effects of inward dentinal fluid flow
heating
mechanical
increased hydrostatic pressure
which direction of dentinal fluid flow is more effective in activating intradental nerves and why
outward, away from the pulp because the rapid flow stretches the nerves
what are stimuli that can bypass the hydrodynamic mechanism
intense heating
intense cooling
electrical current
pain producing chemicals
why do high fillings cause dentinal pain
the force distorts the dentine and alters the tubular fluid flow
describe the properties of the a beta and a delta fibres in the pulp
these are large and small, myelinated nerves
they are activated by hydro dynamic stimuli applied to dentine
they mediate normal dentinal sensitivity
which nerve fibres mediate normal dentinal sensitivity
a beta and a delta
which nerve fibres in the pulp are unmyelinated
c fibres
describe the features of the C fibres in the pulp
active directly by stimuli instead of hydrodynamic mechanism and respond to most forms of intense stimuli
mediate pain associated with pulp inflammation such as caries
branches from which blood vessel provide the pulp
maxillary artery
describe the control of pulp blood flow
- local factors like metabolites
- sympathetic nerves
- somatic afferent nerves
- circulating hormones like adrenaline
- drugs including LA with vasoconstrictors
why do burs need to be cooled
they can damage the pulp if used with a high speed motor
list the functions of pulp nerves
sensory function to mediate pain
control pulp blood vessels via sympathetic for vasoconstriction and afferents for vasodilation
promote neurogenic inflammation
promote dentine formation
facilitate the immune response
what is the immediate response to dental pulp injury
nociceptor activation ie pain
what is the dentine pulp response to injury after one minute
early inflammatory response including kinins, prostaglandins, neuropeptides and then vasodilation
what is the dentine pulp response to injury after 10 minutes
nociceptor sensitisation
extravasation of fluid causing oedema
polymorph migration
what is the dentine pulp response to injury after 100 minutes
enzyme activation, nerve growth factor and monocyte presence
what is the dentine pulp response to injury after one day
nerve sprouting, increasing axonal transport and altered excitability of the central nervous synapses
what is the dentine pulp response to injury after a week
repair - tertiary dentine formation
when is the dentine pulp response to injury completely repaired and recovered
this time is variable so there is no real answer but usually over a week
describe pulpitis
acute inflammation in the dental pulp is similar to that in other tissues except that the pulp cannot swell as it is confined within the pulp chamber
oedema causes an increase in pulp pressure
this can have variable effects on blood flow and nerve excitability
what forms the core of the tooth
the dental pulp complex
main function of the pulp is
to produce dentine
what elements of the pulp provide the characteristic gel elastic behaviour
the matrix and the fibres
why is blood supply and lymphatic drainage important for the pulp
anything that impacts these characteristics will impair the function of the pulp
where does the pulp open to the external environment
at the apex
why is nutrition important for the pulp
allows dentine to grow and produce both the primary and secondary dentine
what is the developmental link between pulp and dentine
they originate from the dental papilla
what is the name of the cells that migrate from the neural crest to create the dental papilla
ectomesenchymal cells
are there blood vessels in normal dentine
no
what is the origin of the dentinal fluid
the extracellular fluid or better from the leakage of pulp capillaries into the interstitial space
what is the flow of dentinal fluid proportional to
pressure inside the pulp
what is the difference between primary and secondary dentine
one is formed during tooth formation and the other starts when the tooth is completely formed, including the root and apex
primary dentine is formed quickly following the pace of the tooth development
when the tooth is complete, the pace of dentine formation is slowed, and this is secondary dentine which is formed throughout your lifetime
what are the two types of tertiary dentine
reactionary dentine, produced by the original odontoblasts faced with aggression. when this aggression is powerful enough to damage these cells the dormant non differentiated stem cells are recruited to differentiate into odontoblasts and produce the reparative dentine
what is the difference between reactionary and reparative dentine described as and why is this
academic difference because they cannot be clinically identified as their origin is not something we can tell by looking at the dentine
what are some instances that cause aggression to the pulp
abrasion caused by masticatory function
functional damage caused by bruxism attrition
occlusal overload causing fractures of enamel in the cervical region (abfraction)
acidic diet causing erosion
aries
operative procedures
what is occlusal equilibration therapy
used to correct the bite surface of the teeth causing tmp disorders.
drill occlusal surface of healthy teeth to fix the tmp
only used in rare and specific cases by a few professionals
what is the most common cause of tooth wear in operative procedures
cutting cavities and preparation of the tooth to receive crowns and bridges
damage can be caused to the pulp even without extending the tooth cutting to dentine. why is this
you can still cause damage to the pulp because of the heat generated during preparation - this is why water is always used
what is reactionary dentine a consequence of
mild stimulus triggering the primary original odontoblasts to produced dentine
what is reparative dentine a consequence of
when stimulus is intense and the primary odontoblasts are destroyed, leading to secondary odontoblasts recruited and laying down reparative dentine
where do secondary odontoblasts originate from
sub odontoblastic layer called hoehls layer
this contains stem cells
what is the name given to the subodontoblastic layer where the stem cells are found
hoehls layer
does tertiary dentine have dentinal tubules
no
function of tertiary dentine
a plug to seal tubules from access to the pulp and protect the vital tissue from the exterior threat
what other function do odontoblasts have aside from forming dentine
they form a permeability barrier between pulp and the dentinal tubules to regulate the exchange of materials between pulp and the tubular extracellular fluid
this exchanging movement happens in both directions
describe the route of innervation for the pulp
trigeminal nerve - maxillary and mandibular branches - alveolar branches - enter pulp at apical foramen
pass along root canal at the centre of the pulp toward the coronal chamber
fan out toward the sub odontoblastic layer and form the plexus of raschow
these terminal branches enter the odontoblastic layer and some of these nerves will enter the dentinal tubules
what is the difference between the nerves entering the tubules at the cusp, coronal portion of the crown and the root
under the cusps, 40% of the tubules have nerves
coronal dentine has 15% tubular innervation
root dentine has 4%.
most axons do not enter the tubes and end in the pulp in the predentine region
why are axons in the pulp relevant to think about
stimulus like thermal, mechanical, chemical etc on the surface of exposed tubules can act on them and increase rate of dentinal fluid flow
this generates action potentials in the intradental nerve and passes to the brain as pain
this is the hydrodynamic mechanism to activate the intradental sensorial nerves and generate pain
what is the consequence of the hydrodynamic mechanism in dentine that generates pain
dentinal fluid can flow outward or inward. stimuli type will determine the different flows.
which stimuli result in the dentinal fluid being driven outward
cooling
drying
evaporating
hypertonic solutions
reduction of hydrostatic pressure
which stimuli result in the dentinal fluid being driven inward
heating
mechanical pressure
increased hydrostatic pressure
which flow of dentinal fluid causes greater stimuli
outward flow as it is rapid and stretches the nerve
is all stimuli due to the movement of dentinal fluid
no, intense temperature changes can affect the intradental nerves directly
electrical current and pain producing chemicals can also affect the nerves
dentinal fluid is associated with pain for many reasons. one is due to fillings. explain this
high fillings such as inlay and inlay restorations will be distorted by occlusal forces and generate pressure to alter the flow of the fluids
what activates the a beta and a delta myelinated fibres
hydrodynamic stimuli applied to dentine
which nerve fibres are responsible for normal dentine sensitivity
a beta and a delta myelinated fibres
what activates the unmyelinated C fibres in dentine
direct stimuli
which fibres are responsible for intense stimulation in the dentinal tubules
c fibres
which fibres are most likely to be associated with pain mediated by pulp inflammation including carious lesions
c fibres
blood supply to the teeth branches from which artery
maxillary artery
does cavity preparation and inflammatory response change the vascular permeability of the pulp
yes it is increases it
what controls pulpal blood flow
local factors like metabolites which will have to be removed and affect blood flow in other tissue
not many details on how this works in the pulp but it is known there are changes in blood flow for instance after exercise
innervation - sympathetic controls blood flow by changing the diameter of the blood vessels - generates vasoconstriction to reduce blood flow
afferent somatic fibres means there are sensorial fibres that when receiving stimulation release peptides which produce vasodilation and increase blood flow
effect of hormones like adrenaline will promote vasoconstriction
vasoconstrictors like adrenaline and fenylpressin are used in anaesthetics
why are uncooled burs problematic
they reduce the blood flow to the pulp
what is the function of pulp nerves
sensory to mediate pain
control of pulp blood flow
afferents generate vasodilation via peptidergic activity aka axon reflex
neuropeptides released in axon reflex promote neurogenic inflammation so the neuropeptides release by the afferent nerves like substance P induce inflammatory responses
neurogenic response also promotes dentine formation
what stimulates the afferent sensorial fibres
changes in dentinal fluid flow
describe the axon reflex mechanism
axon reflex triggered to release vasoactive peptides like substance P and CGRP
these peptides will promote vasodilation to increase permeability
pulp tissue pressure increases
tubular fluid flow increases
what does the time of full pulpal repair depend on
size of the lesion
host response
ability to recognise repair with radiographs
why does the confinement of the pulp chamber impact when there is inflammation
it does not allow swelling so the oedema will increase the pressure, affecting blood flow and nerve excitability
this incapacitates the tissue to perform its function
