OE L6 Dentine Pulp Complex Flashcards
What does pulp contain?
- Loose connective tissue
- Cells
- Nerves
- Vascular supply
Give 5 functions of the pulpal organ.
- Blood supply and nutrition to odontoblasts
- Sensory function, extremes in temparute, pressure or chemical insult
- Defensive function, immune-inflammatory response
- Cells for reparative dentine formation
- Regulation of dentine formation through signalling factors e.g. cytokines
Describe dental pulp organisation.
- Blood vessels and nerves enter and exit through apical formaen
- Each root has at least one canal
- Vessels and nerves become more narrow and branched as they reach the coronal portion of tooth
- In bifurcation zone there are accessory canals called foramina which directly interact with adjacent tissues e.g. periodontal ligament
Describe the dentine-pulp interface.
- Organised layer of odontoblasts adjacent to pulp
- Odontoblasts have strong interactions with cells of pulp and ECM
- Directly beneath odontoblast layer is cell free zone/zone of Weil, a thin layer almost completely devoid of cells
- Beneath cell free zone is cell rich zone
Are there variations in odontoblast structure in the tooth?
Yes.
- Cell size and shape varies depending on tooth region, columnar in crown, cuboidal in mid-root, flattened in apex
- Odontoblasts are smaller near root region
Useful to remember when looking at histological sections to know which part of the tooth you are viewing.
- Cell size and organelle content also reduce with age
What are the 3 types of junctions odontoblasts possess?
- Tight junctions and intermediate junctions between odontoblasts themselves, and between odontoblasts and cells of pulp
- Gap junctions to support orientation of odontoblasts
What organelles are found in the odontoblast cell body?
- Nucleus and mitochondria in periphery
- Organelles involved in translation, packaging and secretion of proteins found in forefront of (golgi, RER, mitochondria)
What is the most abundant cell type in pulp?
Pulpal fibroblasts.
- Younger fibroblasts are more rounded and pulp
- Older are flattened with dense nuclei
What other cells are important in pulp?
Undifferentiated mesenchymal stem cells
What is the role of undifferentiated mesenchymal stem cells?
- Respond to cytokines and growth factors to form new fibroblasts, odontoblast like cells and endothelial cells
- Role in dentine and pulpal repair
Where are undifferentiated mesenchymal stem cells found?
- Cell rich zone (odontoblast like cells)
- Central pulp (fibroblasts)
- Surroudning blood vessels of pulp (enfothelial cells)
All undifferentiated mesenchymal stem cells are of neural crest origin
What is the role of fibroblasts?
- Produce cytokines, growth factors and inflammatory mediators in response to trauma and injury
- Stimulation of reactionary and reparative dentine formation
- Remove damaged ECM components from pulp and replace with newly synthesised and secreted matrix components
Describe the fibrous components of the pulpal matrix.
- Predominantly type 1 collagen, provides strength and protection
- Collagen type III, V and VI
- Oxytalan fibrils
- Elastin in blood vessel walls providing elasticity
Describe the non-fibrous components of the pulpal matrix and their role.
- Proteoglycans: decorin, biglycan, versican and syndecan
Regulate cell signalling, matrix assembly, cell migration, cell proliferation and inhibit mineralisation.
- Glycoproteins: fibronectin, laminin and tenasin
Roles in matrix formation, cell attachment and cell migration.
Which cells act as the first line of defence for the pulp?
Dendiritic cells.
- Initial detection and response to trauma/disease
- Initiate primary immune response
- Capture and present foreign antigens to T-cells
- Increased number of dendritic cells in carious teeth
What other defence cells exist in the pulp?
- T-lymphocytes in small numbers
- Macrophages which removed dead/damaged cells and bacteria and promote tissue epair
At what point do the blood vessels and nerves branch extensively?
At the bifurcation zone and upwards to the coronal portion of the tooth.
Describe the capillaries of the pulp.
Present in the odontoblast layer, between the odontoblasts and in the predentine. Do not enter the dentinal tubules.
There is a sub-odontoblastic capillary plexus.
Describe the lymphatics of the pulp.
Start near the zone of Weil and widen and become larger closer to root apex.
Involved in waste removal and vasoconstriction/dilation due to sympathetic adrenergic nerve endings.
Describe the nerve supply of the pulp.
Nerves run alongside blood vessels.
More branched in coronal portion.
Most branches terminate in odontoblast or subodontoblast regions.
Plexus of Raschkow
- Pronounced plexus of nerves beneath odontoblasts in crown of tooth
- Branches from plexus pass into odontoblast layer and form marginal plexus
- Some can even penetrate into the dentinal tubules unlike blood vessels
ONLY NERVES CAN TRANSVERSE INTO DENTINAL TUBULES
Describe 7 age related changes which occur to pulp.
- Pulp volume decreases due to deposition of secondary dentine (pulp recession)
- Becomes less cellular, poorer response to injury and disease
- Narrowing of apical foramen which can lead to pulp necrosis as vessels and nerves lose access to pulp
- Increased pulp mineralisation
- Reparative dentine producing abilities reduced
- Dead tracts formed, more difficult for odontoblasts to perform functions aiding pulpal tissue
- Pulp stones alled denticles can form
What are denticles?
Stones in the pulp. Divided into true and false denticles.
True: dentine-like structures
False: concentric layers of calcified tissue
