Dentine and Pulp Flashcards
what is the dental pulp?
connective tissue ‘core’ of the tooth
what is 5 things are present in pulp?
- cells
- extracellular components
- nerves
- blood vessels
- lymphatics
what cells are present in pulp?
- odontoblasts
- fibroblasts
- defence cells
what are the extracellular components of pulp?
fibres
- collagen and oxytalan
matrix
- proteoglycans, chondroitin SO4, dermatin SO4
5 functions of the dental pulp
- nutritive (blood vessels)
- dentine growth
- dentine repair (tertiary)
- defence (immune cells and lymphatics)
- neural (sensory pain response)
what are the close links between dentine and pulp/
- developmental links
- structural links
- functional links
dentine-pulp complex
what are the structural links between dentine and pulp?
pulpal elements extend into dentine
- odontoblast processes
- nerve terminals
- immune cells (dendritic cells)
- dentinal fluid
pulp haemodynamics and hydrodynamics
- Fluid leaks from pulp capillaries –>interstitial space
- Some drains by lymphatic
- Some passes along dentinal tubules (dentinal fluid)
- Flow proportional to pulp pressure
Defence role
• To protect tissue avoid microorganism entering pulp as drive force
functional links between dentine and pulp
- formation of secondary and tertiary dentine
- regulates exchange of material between dentine and pulp
types of tooth wear and possible causes
- mastication
- bruxism –> attrition
- abfraction (occlusal overload –> fractures & cervical lesions)
- abrasion - loss due to mechanical actions (not teeth)
- diet (erosion)
- caries
- operative procedures
what is the role of tertiary dentine?
reactionary dentine
- in response to mild stimulus
- laid down by primary odontoblasts
reparative dentine
- in response to intense/harsher stimulus that destroy primary odontoblasts
- laid by secondary odontoblasts
what separates pulp and tubular space?
odontoblast layer
what is the role of the odontoblast layer which separates pulp and tubular space?
permeability barrier
- regulates movement of material between pulp and tubular ECF
- movement may be in either direction
what materials move from pulp to dentine?
- nutrients to sustain cells,
- formation of secondary and tertiary dentine,
- for tubular nerve function (e.g. K=)
what materials move from dentine to pulp?
- medicaments applied to dentine
- diffusion of ‘toxins’ from bacteria, components of filling materials
what nerve supplies most teeth?
branches of alveolar nerve
where do neurovascular bundles enter the pulp?
via apical foramen
what is the passage of neurovascular bundles?
- enter pulp via apical foramen
- pass along root canal in centre of pulp towards coronal pulp chamber
- branches fan out in sub-odontoblastic layer
- terminal branches enter odontoblast layer (some enter dentinal tubules)
what is Raschow’s Plexus?
branches of alveolar nerve which fan out in sub-odontoblastic layer in pulp
what is the spread of dentine innervation?
- 40% under cusps
- 15% coronal dentine
- 4% root dentine
few axons enter tubules; most end in pulp-predentine region
what causes outward dentinal fluid flow?
cooling drying evaporation hypertonic solutions decreased hydrostatic pressure
what causes inward dentinal fluid flow?
heating
mechanical
increased hydrostatic pressure (e.g. syringe)
what dentinal fluid flow is more effective at activating intradental nerves?
outwards dentinal fluid flow
(away from pulp)
RAPID OUTWARD FLOW STRETCHES THE NERVE
4 stimuli that act directly on intradental nerves
- intense heating
- intense cooling
- electrical current
- pain-producing chemicals
what is the most common ways for a restoration to cause dental pain?
distortion onto dentine and creates movement in dentinal fluid flow
‘high’ fillings
A beta and delta fibres in intradental nerves are activated by
hydro-dynamic stimuli applied to dentine
A beta and delta fibres cause what type of pain response in intradental nerves?
likely mediate ‘normal’ general dentinal sensitivity response
C fibres in intradental nerves are activated by
stimuli directly (rather than hydrodynamic mechanism)
respond to most forms of intense stimulation
C fibres cause what type of pain response in intradental nerves?
likely mediate pain associated with pulp inflammtion (e.g. caries)
what is the blood supply to teeth?
branches of maxillary artery
what are the 5 branches of the maxillary artery?
- deep auricular artery
- anterior tympanic artery
- medial meningeal artery
- accessory meningeal artery
- inferior alveolar artery
4 factors on pulp blood flow control
- local factors e.g. metabolites
- nerves (sympathetic, somatic afferents)
- circulating hormones e.g. adrenaline
- drugs e.g. LA with vasoconstrictors
what does increase in pulp pressure do to dentinal fluid movement?
causes increase in outward flow in dentinal tubules (increase in nutrients)
4 functions of pulp nerves
- sensory (mediate pain)
- control of pulp blood vessels (sympathetic: vasoconstrictor; afferents: vasodilator)
- promote neurogenic inflammation (neuropeptides, subst P, CGRP)
- promote dentine formation
immediate dentine-pulp response to injury
nociceptor activation - pain
after approx. 1 min dentine-pulp response to injury
early inflammatory response
- kinins, prostaglandins, neuropeptides
vasodilation - swelling
after approx. 10 mins dentine-pulp response to injury
nociceptor sensitisation e.g. sorer when biting
extravasation of fluid, oedema
polymorph migration - recruitment of cells, presence of agents of cell inflammatory response
after approx 100 mins dentine-pulp response to injury
enzyme activation; nerve growth factor
monocyte presence
after approx. 1 day dentine-pulp response to injury
nerve sprouting (NGF)
increased axonal transport
altered excitability of CNS synapses
- small local sensitisation of response; become more later - small lesions can cause large response to pain
after approx. 1 week dentine-pulp response to injury
repair - tertiary dentine formation
variable completion and repair/recovery
what is pulpitis?
toothache
acute inflammation in the dental pulp is similar to other tissues except pulp cannot swell as it is confined in pulp chamber
oedema causes increase in pulp pressure
- variable effects on blood flow and nerve excitability
