mature dentin is only ______% calcified with _____ ______
70
calcium hydroxyapatite
dentin makes up the_____ of the tooth and protects the ______
bulk
pulp
t/f dentin cannot be removed with instrumentation
false-it CAN be removed with instrumentation
where does dentin get its nutrition from?
pulp (dentin is avascular)
t/f dentin has its own blood supply
false-dentin is avascular
how does dentin feel compared to enamel?
rougher
what is the process of apposition of dentin?
out cells of dental papilla form odontoblasts
odontoblasts lay down predentin
they leave one long cytoplasmic extension in the dentin (odontoblastic process)
keeps going throughout life because odontoblasts remain in the pulp
what cells form odontoblasts?
outer cells of the dental papilla
what is the long cytopasmic extension left by odontoblasts in the dentin?
odontoblastic process
where do the odontoblasts live?
in the pulp
t/f apposition of dentin can be made all throughout life?
true
what are the two steps of maturation of dentin?
primary mineralization phase
secondary mineralization phase
what phase of maturation of dentin is described as this: as globules calcify, they expand and fuse together and create globular dentin
primary mineralization phase
what phase of maturation of dentin is when globules calcify they expand but do not fuse completely. Creates interglobular dentin that is less mineralized
secondary mineralization
what does the primary mineralization phase create?
globular dentin
what does secondary mineralization create?
interglobular dentin
what is less mineralized globular dentin or interglobular dentin?
interglobular dentin
what are 3 components of the dentinal tubules?
odontoblastic process
dentinal fluid
afferent axon
what extends from the DEJ to the outer wall of the pulp?
dentinal tubules
what is the tail end of the odontoblast?
odontoblastic process
what is the tissue fluid surrounding the cell membrane of the odontoblast?
dentinal fluid
what is the nerve that receives sensation for the tooth and where is it located in the tooth?
afferent axon
located in the pulp
the _____ of the tubule relfects the pathway the odontoblast took
direction
what is the overall tubule course called which resembles a large S
primary curvature
what resembles a large S within the dentin?
primary curvature of the dentinal tubule
what are the small delicate curves of the dentinal tubules called and what do they show?
secondary curvature
shows daily changes in the odontoblast direction during apposition
what are two ways the types of dentin are described?
location and time
what are the four types of dentin by location?
peritubular dentin
intertubular dentin
mantle dentin
circumpulpal dentin
what type of dentin creates the dentinal tubule?
peritubualar dentin
where is the peritublar dentin located?
walls of dentinal tubule
what type of dentin is found between each of the tubules?
intertubular dentin
where is intertubular dentin found?
between each of the tubules
what type of dentin is the first to form and is closest to the DEJ?
mantal dentin
what is mantle dentin?
first to form and closest to the DEJ
what type of dentin surrounds the pulp chamber?
circumpulpal dentin
what is circumpulpal dentin?
dentin that surrounds the pulp chamber
what are the three types of dentin by time of formation?
primary dentin
secondary dentin
tertiary dentin
what type of dentin is formed before the completion of the apical foramen?
primary dentin
what type of dentin has normal alignment of tubules and is more calcified than secondary?
primary dentin
when does primary dentin form?
before the completion of the apical foramen
what type of dentin forms after the completion of the apical foramen
secondary dentin
t/f secondary dentin is more calcified than primary dentin and t/f is formed to protect the pulp.
false-secondary dentin is less calcified than primary dentin
true
when does secondary dentin form?
after the completion of the apical foramen
what type of dentin forms in response to trauma?
tertiary dentin
t/f tertiary dentin has irregular alignment of tubules because it is laid quickly and t/f it is formed to protect the pulp.
true
false-formed to protect the outer layer of dentin
what is formed because of trauma or age and involves the odontoblastic process to die and leave the tubule
sclerotic dentin
what is the tubule filled with when the odontoblastic process dies and leaves the tubule
more dentin
what is sclerotic dentin?
formed in the tubule because of trauma or age, the odontoplatic process dies and leaves the tubule and then is filled with dentin
t/f imbrication lines of von ebner are just like incremental lines of retzius
true
how are imbrication lines of von ebner laid down?
cyclically
what are darkened areas that show some sort of disturbance in the apposition
contour lines of owen
what is an example of a contour lines of owen
neonatal line
what is the most pronounced line of contour lines of owen
neonatal line
t/f the contour lines of owen are any line that is darker than normal?
true
describe the age changes of dentin
diameter of tubules starts to narrow as more dentin is laid and seals off the communication between the dentin and the pulp
t/f with age changes in dentin the diameter of the tubules start to widen
false-tubules start to narrow as more dentin is laid
t/f dentin is more calcified than enamel and is less prone to caries
false- dentin is less calcified than enamel and is more prone to caries
bacteria have been seen using the _____ ____ as chutes towards the _____
dentinal tubules
pulp
why can a small cavity in the enamel be monitered but once it has gotten to the dentin it must be repaired?
bacteria uses the dentinal tubules as chutes towards the pulp
why is the dentin hypersensitive
afferent axons are in the dentinal tubules
afferent axons in your dentinal tubules translate all stimuli into what?
pain
what is the exact mechanism of the afferent axon stimuli?
unknown
what can help diminish hypersensitivity?
occluding the tubules-fluoride, laster treatments or composite fillings
what is the active ingredient that helps to occlude tubules?