quiz on Lecture 8 Flashcards
composition of dentin: inorganic, organic, and water
inorganic: 70%
organic: 20%
water: 10%
dentin is covered by what in the crown, and by what on the root
enamel; cementum
dentin protects the pulp and
makes up the bulk of the tooth
is dentin vascular or avascular
avascular
what color is dentin
yellowish; esp during attrition(occurs faster if dentin is exposed rather than for enamel); not whiter than enamel
dentin is also:
slightly elastic
apposition of dentin occurs how often?
throughout the life of the tooth; does not stop after eruption like enamel
odontoblasts were peripheral cells of the what
dental papilla
where do odontoblast start making dentin?
at DEJ
this is surrounded by predentin(newly deposited uncalcified dentin matrix) and goes toward the inside; long cellular extension located within dentinal tubule
odontoblastic processes
lines of von ebner are what?
incremental lines; hypomineralized
where does mineralization occur in dentin
predentin/dentin complex
as the previous later of predentin becomes dentin;
a new layer of predentin is formed
predentin matures by forming these which mineralize/calcify into mature dentin and fuse like water colors on paper
globules
layer- areas of calcified dentin with hypomineralized areas at their surface(contains interglobular dentin); in book: both primary and secondary mineralization have occured with complete crystalline fusion and appear as lighter rounded areas on a microscope
globular dentin
occurs in coronal dentin near DEJ; hypomineralized area between calcified globules where globules are fused incompletely
interglobular dentin
dentin tubules are hypomineralized or hyper?
hypo
process are enclosed in a
dentinal tubule
dentinal tubules can run from DEJ
the periphery of the pulp
tubules are crowded near the
pulp due to narrowing of this region
tubules follow S-shape path along length of
tubules
movement of odontoblasts to a narrower area
primary curve
small waves, movement during night and day of odontoblasts
secondary curve
diameter of dentinal tubules
4 um wide
lateral branches that arise at right angles to the main tubule
canaliculi
tubules that are obliterated by peritubular dentin(makes up inside of tubule); this forms a protective mechanism to wall of bacteria to protect pulp
sclerotic dentin
air filled tubules caused by death of odontoblastic process, appear black because of histologic stain of empty dentinal tubules
dead tracts
caused by looping of dentinal tubules; only found in root cementum but is in dentin; adjacent to DCJ
tomes granular layer
1st dentin made because it is closer to DEJ
mantle dentin
lies immediately adjacent to DEJ(between DEJ and globular layer)
mantle dentin
how thick is mantle dentin
10-30 um thick
how are the collagen groups arranged in
perpendicular to DEJ
is mantle dentin more or less calcified than circumpulpal?
less calcified
dentin that is closer to the pulp
circumpulpal dentin
this layer of dentin is around outer pulpal wall; between globular layer and pulp
circumpulpal
this dentin layer has finer collagen fibers and is more calcified than mantle dentin
circumpulpal dentin
fibers are parallel to DEJ
circumpulpal
S curve goes through mantle and
circumpulpal
fill up tubules with sclerotic; formed around odontoblastic process(makes wall of dentinal tubules
peritubular dentin
calcification of peritubular dentin
highly calcified
what dentin’s deposition can cause tubules to narrow with age
peritubular dentin
this type of dentin is located between dentinal tubules and is less calcifed
intertubular dentin
formed before completion of apical foramen; closer to DEJ
primary dentin
includes mantle and circumpulpal dentin(big s curve, bulk of dentin) and includes globular layer
primary dentin
how much of primary dentin is made per day?
4um
formed after completion of the apical foramen; formed at a slower rate; closer to pulp(thinner than primary)
secondary dentin
which kind of dentin: pulp gets narrower because odontoblasts keep traveling inward making dentin
secondary dentin
forms rapidly in localized areas in response to trauma of dentinal tubules; not everyone has it; makes pulp narrower; lighter and right under dead tracts
tertiary, reactive, or reparative dentin
under tertiary dentin
cavity preparations, attrition or bruxism, thermal water sprays
when dentinal tubules become exposed to outside environment make direct contact with pulp
sensory conduction
tubules serve as entry to cariogenic microorganisms when caries extend from enamel into dentin
caries
dentin is exposed as reseult of caries, cavity prep, gingival recession or attrition; open dentinal tubules may be painful
dentinal hypersensitivity
fluid open exposed tubules begin to evaporate; the movement of fluid caused by evaporation may stimulate nerves nearest odontoblast to produce pain; explains dentin sensitivity
hydrodynamic theory
occurs at a more rapid rate because its mineralized content is lower
attrition
odontoblasts in the area of the affected tubules may perish because of the injury, but neighboring undifferentiated mesenchymal cells of the pulp can move to the area and become odontoblasts
reparative dentin
if the tertiary dentin is formed by existing odontoblasts, considered
reactive dentin
