Oral Biology Flashcards
What is another word for Hoehl’s layer?
The cell free zone of Weil
What zone lies next to the pulp and blends with it?
Cell rich zone
What does the pulp core zone comprise and what zone does it lie below?
prominent blood vessels and nerves and is present below the cell rich zone.
What are the layers of the pulp from inner to outer?
Pulp core
Cell rich zone
Cell-free zone of Weil
Odontoblast layer
What lies in the cell-free zone of Weil?
rich in both capillaries and nerve networks.
What is the outer layer of the pulp and what does it lie under?
odontoblast layer which contains odontoblasts and lies next to the predentin and mature dentin.
What is the odontoblast layer of the dental pulp and what is its purpose?
form a natural barrier between mineralized tissues, dentin, and soft tissues, dental pulp, of the vital tooth, and they first recognize caries-related pathogens and sense external irritations
Are odontoblasts polarised?
Yes, nucleus lies towards the pulp
What is the name of the projection from odontoblasts into the pre-dentine and what do they do?
odontoblast process
function in the secretion, assembly and mineralization of dentin during development, participate in mechanosensation, and aid in dentin repair in mature teeth
What is the main role of an odontoblast?
to form dentine and protect pulp tissue
What is the main role of fibroblasts?
synthesise and secrete collagen and non-collagenous proteins, degrading old/damaged proteins and formation of connective tissue
What is a lymphocyte?
Inflammatory cells
immune cell that is made in the bone marrow and is found in the blood and in lymph tissue
What is a macrophage?
Inflammatory cell
specialised cells involved in the detection, phagocytosis and destruction of bacteria and other harmful organisms
What is a histocyte?
inflammatory cell
phagocytic cell present in connective tissue
What is a pulpal dendritic cell and what do they do?
Inflammatory cell
potent antigen presenting cells that capture, process, and then present antigens to T cells when they mature
What are the compositions of collagen present in the ECM in pulp?
type 1 - 56%
type II - 41%
What is type 1 collagen?
most abundant collagen found in connective tissues and the primary determinant of tensile strength of the ECM
What is type II collagen?
protein that is part of the cartilage, bone, and other types of connective tissues
What are the components of pulpal extracellular matrix?
Collagen
Phosphorylated ECM proteins
Non-phosphorylated ECM proteins
Proteoglycans
Growth factors
Enzymes
What is the diameter of an arteriole?
35-45 micro m
What is the diameter of a capillary?
8 micro m
What is the diameter of a venule?
over 50 micro m
Do venules have valves?
no
What does stimulation to dentine result in via neurogenic control?
Pain
increased blood flow
axon reflex causes vasodilation and increases capillary permeability and sensitivity
What are four factors that control pulpal blood vessels?
Efferent autonomic nerves
Neurogenic control
Local factors
Constant volume problem
How many axons enter a premolar?
2500
What is the difference between afferent and efferent neurons?
Afferent - information from sensory receptors to the CNS
Efferent - information from the CNS to muscles and glands
Where do efferent nerves travel to and from?
From CNS to muscles and glands
Where do afferent nerves travel to and from?
From sensory receptors to the CNS
Are the majority of nerves involved in pulpal innervation myelinated or non-myelinated?
70-80% non-myelinated
Of the remaining 20-30% of pulpal nerves which are myelinated, what types of nerves make up this proportion?
90% A delta fibres
10% A beta fibres
Where is the Plexus of Raschkow classically found?
In the cell free zone
What is the function of the Plexus of Raschkow?
monitors sensations of pain
What kind of sensations are transmitted by A delta fibres and what are A delta fibres?
afferent fibres of nociceptors - larger and the most rapidly conducting
associated with the sharp, well-localized pain activated by mechanical and thermal stimuli.
What is a nociceptor?
Pain receptor
sensory receptors that detect signals from damaged tissue or the threat of damage
What are A beta fibres and what sensations are transmitted by them?
touch receptor
afferent fibres from stretch receptors. Aβ fibres from the skin are mostly dedicated to touch
What are embryonic stem cells and what can they differentiate into?
undifferentiated cells in developing tissues
can differentiate into any cell type
What are adult stem cells and what can they differentiate into?
undifferentiated cells found living within specific differentiated tissues in our bodies that can renew themselves or generate new cells that can replenish dead or damaged tissue
What is the function of dental pulp stem cells?
production of odontoblast like cells to create reparative dentin support
What are stem cells from human exfoliated deciduous teeth and what can they form?
pluripotent cells that can be retrieved from primary teeth
can form bone or dentine
What does SCAP stand for?
Stem cells from apical papilla
What do growth factors induce?
induce stem cell migration and differentiation
What initiates the migration and differentiation of stem cells?
growth factors
What are two examples of growth factors present in the dentine?
TGF-beta 1
BMP - bone morphogenetic protein
What can trigger the release of growth factor and subsequent stimulation of stem cell migration and differentiation?
an acid environment eg. caries
What are two medicaments that can be applied to cause inflammatory changes in the hope of stem cell differentiation and dentine formation to maintain pulp vitality?
Ca(OH)2
MTA
What kind of dentine is produced from a mild stimulus causing dentinogenesis and how is it formed?
Reactionary dentine - odontoblasts produce more dentine
What kind of dentine is produced from a strong stimulus eg. caries causing dentinogenesis and how is it formed?
Reparative dentine - aggressive insult causes odontoblasts to die. Stem cells migrate, proliferate and form reparative dentine
