Endodontium Flashcards
What is the odontoblast layer and what is its function
Permeability barrier between the pulp and dentine tubules
Regulates exchange of materials between the pulp and the ECF
Describe the exchange of materials from the pulp to dentine
Nutrients to sustain cells
Calcium and phosphates for formation of 2* and 3* dentine
Na2+ and K+ for action potentials
Describe the exchange of materials from dentine to the pulp
Medicaments applied to dentine
Components from filling materials
Toxins produced from bacteria in carious lesions
Describe the anatomy of the pulp nerves
Branches of alveolar nerves enter the pulp via the apical foramen
Pass along root canal in the centre of the pulp towards the coronal pulp chamber
Branches out in the sub-odontoblastic layer to form Raschow’s plexus
Terminal branches enter odontoblastic layer and some nerves enter dentinal tubules
What proportion of dentine tubules contain nerves
Under cusps 40% of tubules contain nerves
15% in coronal dentine
4% in root dentine
Describe the hydrodynamic mechanism
Stimulus acts on open tubules causing an increased rate of dentinal fluid flow
This generates APs in intra-dental nerves
The APs pass to the brain to cause pain
What is the purpose of the hydrodynamic mechanism
For activating intradental sensory nerves to cause pain
What are the hydrodynamic effects of outward fluid flow
Cooling
Drying, evaporation
Hypertonic solutions
Decreased hydrostatic pressure
What are the hydrodynamic effects of inwards fluid flow
Heating
Mechanical pressure
Increased hydrostatic pressure
What type of fluid flow is more effective in activating intradental nerves and why
Outward flow as it stretches the nerves and causes greater stimuli
Which stimuli have nothing to do with dentinal fluid and how do these stimuli work
Intense heating Intense cooling Electrical current Pain-producing chemicals These act directly on intradental nerves
How can high fillings cause dentinal pain
The inlays and onlay restorations will be distorted by occlusal forces and generate pressure to alter the flow of the fluids
How are Ab and As fibre intradental nerves activated and what do they cause
Activated by hydrodynamic stimuli applied to dentine
Responsible for the normal dentine sensitivity
How are C fibre intradental nerves activated and what do they cause
Activated directly by stimuli rather than the hydrodynamic mechanism
Respond to most forms of intense stimulation
Mediate pain associated with pulp inflammation - caries
What factors control pulp blood flow
Local factors - metabolites
Nerves
Circulating hormones
Drugs
How do nerves control pulp blood flow
Sympathetic - controls flow by changing diameter of blood vessels, generates vasoconstriction, reducing blood flow
Somatic afferent peptidergic - sensory fibres that when stimulated, release peptides (substance P) which cause vasodilation, increasing blood flow
How do circulating hormones control pulp blood flow
Adrenaline promotes vasoconstriction
How can drugs control pulp blood flow
Vasoconstrictors such as adrenaline and felypressin are used in local anaesthetics
What type of drilling can cause irreversible pulpal damage
An uncooled bur with high speed motor
What are the functions of pulp nerves
Sensory - mediate pain
Sympathetic and afferent - control pulp blood flow
Promote neurogenic inflammation and induce inflammation
Promote dentine formation
Facilitate the immune response
Describe the pulps neurogenic effect on inflammation
Afferent sensory fibres are stimulated by changes in dentinal fluid flow, causing the release of vasoactive and immune active peptides
These promote vasodilation and increase vascular permeability causing increased pulp tissue pressure
This will increase tubular fluid flow
What is a pulpitis
Acute inflammation in the dental pulp
Describe the events of a pulpitis
The pulp cannot swell as it is confined within the pulp chamber
Oedema causes in increase in pulp pressure
This can have effects on blood flow and nerve excitability
This incapacitated the tissues to perform their function
What is the immediate dentine-pulp response to injury
Nociceptor activation triggers pain
