Dentin: Gross Structure and Composition Flashcards
T/F. Both pulp and dentin are connective tissues.
True
Which structure is mineralized connective tissue covering pulp with no blood vessels or whole cells? It does contain odontoblast processes and nerve endings.
dentin
Which structure is a soft connective tissue in the tooth center that is not mineralized and contains blood vessels and whole cells?
pulp
Where are the cell bodies for the nerve endings in dentin located?
trigeminal ganglion
What is the clinical significance of dentin?
- quantitative
2, protective of both the pulp and enamel
Which is harder, stiffer and has a higher compressive strength (flexible)?
Hardness = Enamel
Stiffness = Enamel
Compressive strength = Dentin
T/F. Enamel cushions the underlying dentin.
False, dentin cushions the overlying more brittle enamel.
T/F. Conditions that affect dentin also affect enamel.
True. Example, dentinogenesis imperfecta, enamel often splits.
The DEJ is ____ which facilitates adhesion and resist shearing forces during mastication.
scalloped
When does dentinogenesis begin?
during the Bell Stage
T/F. Just prior to dentinogenesis the tissue layers of the dental organ are present, the crown outline is present and there are no odontoblasts or ameloblasts.
True.
Dentinogenesis occurs from the ___ tips to the ___.
cusp; cervix
What are the four processes that occur during the late bell stage?
- inner enamel epithelial cells become ameloblasts
- undifferentiated mesenchymal cells (dental papilla) form odontoblasts
- dentin is secreted
- enamel is secreted
What two fates does the undifferentiated mesenchymal cells undergo?
- preodontoblasts
2. dental papilla/pulp
Initially the odontoblasts have many ____ that eventually decrease in number to 1-2. These cells secrete ___ ___ collagen into the matrix and as they move closer towards the pulp the matrix nearer the ___ ___ is mineralized.
processes; type 1; basal lamina
During the ___ bell stage, dentinogenesis is formed from the periphery to the ___ center.
late; pulp
___ signal for odontoblast differentiation is secreted from the enamel ___ at the site of the enamel ___. The major signaling/growth factors is ___.
Inductive; organ; knot; Wnt10a
What evidence suggests that there is a wave of odontoblast differentiation?
Wnt10a is first expressed in the enamel knot
Then in pre-odontoblast at the cusp tip
Then in successively more cervical parts of the teeth.
Adding Wnt10a induces ___ ___ (___), a molecule expressed by mature odontoblasts.
dentin sialophosphoprotein ( DSPP)
Odontoblast secrete an ___ matrix that is later mineralized.
organic
What is the name of unmineralized organic matrix of dentin?
predentin
What are the two requirements for mineralization?
- Ca+ and phosphate
2. initiation of crystal formation
___ comes from free ions in the plasma and ___ comes from plasma and the cleavage of organic molecules in odontoblast by ___ ___ enzyme.
Ca+; phosphate; alkaline phosphate
Where are Ca+ and phosphate transported to?
predentin through and between odontoblasts
The initiation of crystal formation involves the ___ (initial) and ___ (subsequent) stages.
mantle; circumpulpal
The mantle dentin formation is referring to dentin at the ___ and the principal component of organic matrix is ___ ___ ___. The mantle dentin is secreted by ___ and contains relatively large ___ oriented at ___ ___ to basal lamina/future DEJ.
DEJ; type 1 collagen; odontoblasts; fibrils; right angles
Mineralization of mantle dentin occurs in matrix ___ that are synthesized by ___.
vesicles; odontoblast
As the odontoblasts migrate toward the pulp center, what forms around the one process that dominates?
dentin
___ dentin formation occurs interior to mantle dentin. It is ___ but it’s overall process is similar - organic matrix is secreted then mineralized.
Cirucmpulpal; thicker