Exam 3 - Dentin Pulp Complex II Colombo Flashcards
Primary cell type of dental pulp
Fibroblasts, followed by odontoblasts
Dental pulp arises from:
Dental papilla (ectomesenchymal tissue)
Function of dental pulp
- support structures for the mineralized components of the tooth
- contains blood vessels, innervation, fibroblasts, pool of immune cells, pool of progenitor cells for replacement and repair
4 histological zones of dental pulp (from outer to inner)
- odontoblast layer
- cell free zone of Weil
- Cell rich (Cell dense zone)
- Pulp core
Describe the dental pulp ECM
- soft connective tissue matrix
- comprised of collagen III and I
- numerous non-collagenous proteoglycans and glycoproteins
What happens with dental pulp ECM with age?
Collagen content increases, fibrils aggregate into larger bundles (greatest concentration apically)
What is found in the ground substance of the pulp?
- proteoglycans (GAG chains)
- glycoproteins
- water
What proteoglycans are found in the pulp?
- chondroitin-6-sulfate
- chondroitin-4-sulfate
- heparin sulfate
- dermatan sulfate
- keratan sulfate
Describe the structure of odontoblasts
- polarized cells
- elongated nucleus at the pulpal side of the cell
- secretory components (golgi) towards dentinal side
In the crown, odontoblasts are _____ compared to the root where they are ____
Larger and more columnar; more cuboidal
Odontoblasts form a discrete layer of cells held together by:
Adherens junctions/junctional complexes
gives a degree of permeability to the OD layer - serum proteins may pass
Odontoblasts can form gap junctions with:
Pulpal fibroblasts
Function of odontoblasts
- Creation and maintenance of dentin; supported by the rest of the pulp
- production/secretion of collagen and non-collagenous proteins
- production/sequestration of key growth factors in dentin matrix
- release of secretory vesicles from the OD process
What growth factors are produced/sequestered by odontoblasts?
- VEGF
- TGF B1
- BMP-2
Odontoblasts form _____ throughout their lifetime
peritubular dentin
Describe aged odontoblasts
- fewer organelles
- less secretory activity
- nucleus somewhat more central
OD turnover: assumed to be _____, can be replaced from _____
Long lived; can be replaced from mesenchymal progenitor pool
Where are fibroblasts found in the dentin-pulp complex?
Pulp core, cell rich zone
Fibroblasts function in dentin-pulp complex
produce and maintain the supportive matrix of the pulpal tissue
The pulpal matrix supports:
- progenitor cells
- immune cells
- vasculature
- lymph
- nervous tissues
______ may have a role in facilitating mesenchymal progenitor cell recruitment and differentiation
Fibroblasts
Where are mesenchymal progenitor cells found?
Dental pulp
In response to damage to dentin, ____ are recruited to form new odontoblast-like cells
dental pulp progenitor cells
involved in reparative dentin formation
What immune cells are present in the dental pulp?
- Macrophages (innate immunity)
- dendritic cells (acquired immunity)
- T and B lymphocytes
Healthy pulp has a key role in:
Cell turnover and clearance; involved in immune response via IL-1B, TNFa
Where are dendritic cells found in the pulp?
Under odontoblast layer
Dendritic cells are closely associated with ____ of the pulp to coordinate tissue responses
Neuronal/vascular components
When would T and B lymphocytes primarily be found in pulp?
When there is an infection
Pulp vasculature arises from:
- external carotid arteries
- superior/inferior alveolar arteries
There are ____ arterioles per root that access the pulp through the ____ and spread upwards into the coronal pulp
4-8; apical foramen
Progression of vascular supply to the dental pulp
- Arterioles, capillaries, venules
- arterioles branch, anastomose to venules in capillary plexi located in cell free zone below odontoblasts
- venules leave apical foramen, connect to superior/inferior alveolar veins –> internal jugular vein
Where is the capillary network found in the pulp?
In the cell free zone (during primary dentin formation, present in odontoblast layer)
As arterioles proceed into the pulp, ____ increases, ____ decreases
Caliber; vessel wall
Dental pulp is highly innervated by nerves which enter through ____ and in close contact with ____
Apical foramen; blood vessels
Nerve fibers branch out through the coronal pulp, forming the:
Plexus of Raschkow
not found in the root pulp! only branches of nerve fibers
Incoming nerve fibers of the pulp consist of:
- afferent nerves from CN 5
- sympathetic branches from superior cervical ganglion (controls blood flow)
Functions of nerve fibers in the pulp
- control blood flow
- nociception
- immune response?
Sensory innervation of dentin: nerve bundles consist of both -
Myelinated ‘A-delta’ and unmyelinated “C” axons
Does myelination increase/stay the same/decrease as fibers proceed towards the coronal pulp?
Decreases
A minority of unmyelinated axons pass into:
dentinal tubules closely associated with odontoblasts
What happens to dental pulp progenitor cells in diseases pulp?
Repair function is unpaired
Pulp is responsive to external stimuli through:
All cell types operating together
What are the proposed models of how dentin sensitivity occurs?
- direct innervation (nerves in some tubules but minority)
- Odontoblast nociception (anatomically do not synapse extensively with pulpal nerves, but gap junctions exist)
- Tubule fluid conductance
Pulp stones are:
Mineralized tissue formed inappropriately in the pulp
Pulp stones can be:
- free
- surrounded by soft pulp tissue
- attached/bound to dentin
- embedded in secondary dentin
Pulp stones can occur around:
Collagen fibers, dead cell aggregates/thrombi
Pulp stone effects
can grow large enough to compress pulp and make debridement difficult
Age related changed in pulp
- recession due to 2ndary dentin formation
- cell aging, reduction in cell response to stimuli
- decrease in pulp permeability (more brittle teeth)
- loss of nerve axons and decrease in sensitivity
- dystrophic calcification in central pulp
