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What is orthodentin classified into?
Orthodentin is classified as primary, secondary and tertiary
What is primary dentin comprised of?
Regular tubular dentin formed prior to eruption which includes first formed mantle dentin
What is secondary dentin comprised of?
Regular circumpulpal orthodentin formed (continuous with tubes of primary dentin) at a slower rate throughout the remaining life of the tooth.
What is tertiary dentin compromised of?
Irregular dentin formed focally in response to noxious stimuli
What noxious stimuli cause tertiary dentin to form?
Dental caries, tooth wear, cavity preparation, and restorative procedures
Tertiary dentin is also known by these 7 terms, they are:
- 1. irregular secondary dentin
- 2. irritation dentin
- 3. reparative dentin
- 4. irregular dentin
- 5. reaction dentin
- 6. replacement dentin
- 7. defense dentin
True or false: Barring injury, postmitotic odontoblasts survive for the life of the tooth
The phenotype of odontoblasts is defined by its _______ and its ________
morphology, polarized secretion
Can odontoblasts be isolated alone?
No, but immortalized pulp cell lines with odontoblast like cell features have been made
What is the cell rich layer of Hohl derived from? Explain the steps.
- Before terminal differentiation and during the last cell division of the preodontoblast
- 1. daughter cell moves close to dental basement membrane
- 2. inductive signal received by one daughter cell to go to odontoblast
- 3. the other cells sadly does not and adds to pool of CRLH (cell rich layer of hohl)
Cells in CRLH contribute to the _______ cell population for ________ cell_________ during ________ __________.
- 1. progenitor
- 2. ondontoblast-like
- 3. differentiation
- 4. tertiary dentinogenesis
During tertiary dentinogenesis it is required to have _________ activity.
Angiogenic activity is monitored by what factor?
VEGF: vascular endothelial growth factor
Name cytologic features of the odontoblast?
- 1. basal nucleus with parallel stacks of rough ER
- 2. prominent Golgi aparatus
- 3. saccules are more distended on the mature side of the granules
- 4. terminal web of transverse microfibrils define cell from processes
_____ proposed the concept of ___ levels of secretion from the odontoblast.
Describe the two levels of secretion.
- Proximal end secretes matrix of collagen and proteogylcans which reaches the advancing front after 24H
- Distal level secretes non-collagenous matrix compnents including phosphoproteins, this reaches the front in minutes
Which level by Linde is implicated in the mineralization of predentin and how?
- Distal level
- Nucleators for hydroxyapatite crystal formation
What MMPs are responsible for remodeling near the mineralization front?
2, 9, 20
What are the MMPs involved in?
- Onset of dentin mineralization
- regulation of mineralization in mantle dentin
- processing of dentin sialophosphoprotein (DSPP)
Odontoblasts are similar to what other cells ultrastructural network?
________ primary curvature of the _______ ________ in the crown is an effect of the ________ of odontoblasts as they move toward the center of the pulp.
- dentinal tubules
Greatest tubular density is nearer ____
to the pulp
Calcium passes through what are of the odontoblast layer to reach the mineralization front?
True or False. High concentrations of calcium are at the proximal secretory pole of the odontoblast?
False, it is distally secreted. It is a non-collagenous matrix component.
Globules of hydroxyapatite are known as?
Mantle dentin formation involves _____ _____ that secrete ATPase and phosphohydrolytic enzymes.
What comprises the bulk of circumpulpal dentin?
Peritubular dentin is more or less mineralized?
Dentinal tubules are tapered structures and vary in diameter from ___mm near the pulp to ___mm near the DEJ.
Describe sclerotic dentin.
- Occluded dentinal tubules that appear translucent and are mostly found:
- apical third
- crown midway to the pulp
- outer surface of tooth
- pulp surface of the dentin
True or False. Dentin deposition is slower in the crown than in the root during primary odontogenesis.
False, it is slower in the root.
What does TGF stand for?
Transforming growth factor
Greater amounts of secondary dentin is deposited on the ____ and ____ of the pulp chamber.
Floor and roof.
Why is primary and secondary dentin formation similar?
The tubules made in secondary dentinogenesis are continuous with the matrix of primary dentin and therefore are made by the same odontoblast.
What is the range of secondary dentin deposition per day?
1 to 16 micrometers
Describe reactionary dentin in tertiary dentinogenesis.
- Produced by postmitotic odontoblasts
- Milder stimuli
Describe reparative dentin in tertiary dentinogenesis.
- New generation of odontoblast like cells replacing dead postmitotic odontoblasts
- Stronger stimuli
EDTA has been shown to solubilize _____ from dentin matrix leading to release of signals need to induce reactionary dentin formation.
What does EDTA stand for?
ethylene diamine tetra acetic acid
____ was found to be the most important factor determining the secretion of reactionary dentin.
RDT or remaining dentinal thickness
Maximum reactionary dentin formation was found with an RDT between?
between .5 and .25mm
Reactionary dentin secretion is most affected by which restorative material?
Calcium hydroxide followed by resin, rmgi, and zoe
In deep cavities (RDT less than ___mm), little more than __% odontoblast survival may be seen.
...as in shallower cavities odontoblast survival is about __% or greater
Which time interval is associated with the most reactionary dentin secretion when treated with EDTA?
60 second, followed by 120, and then 0
The _______ response of tertiary dentin will always take place at sites of ______ ______ because of the loss of odontoblasts and the need for ______ _______formation.
- pulpal exposure
- dentin bridge
What is the range of appearance of reparative dentin?
regular tubular to dysplastic atubular
_______ dentinogenesis is often preceded by secretion of a _____ _______that is atubular and associated with rather _______ cells with poorly developed organelles on its formative surface.
- fibrodentin matrix
The three critical steps for reparative dentinogenesis are
- 1. recruitment of progenitor cells
- 2. signaling of odontoblast-like cell diferentiation
- 3. subsequent upregulation of matrix secretion by these cells
Isolated pulp cells exhibit similar molecular phenotype to
Bone marrow stem cells
DPSC stands for
dental pulp stem cells
SHED stands for
exfoliated human primary teeth cells
Other than the daughter cells of post mitotic odontoblast what three other cells are responsible for progenitor of reparative dentin
- perivascular (pericytes) cells
- undifferentiated mesenchymal cells
What are tunnel defects?
They exist in dentinal bridge and are multiple perforations cause by imperfections in reparative dentin formation.
What two mineralization-promoting agents can be used to promote development of odontoblast-like cells?
Dexamethasone and beta-glycerophosphate
Where does calcium build up in the odontoblast during dentin mineralization?
In the Golgi apparatus and mitochondria but not in secretory vacuoles
What is the circadian rhythm of dentin deposition in primary dentinogenesis attributed to?
Peripheral adrenergic neurons that produce variations in blood flow to the odontoblasts.