mature dentin is only _____ calcified with calcium ____________
70%
calcium hydroxyapatite
(enamel 98%)
what tooth structure makes up the bulk of the tooth?
dentin
what does dentin protect?
the pulp
is dentin smoother or rougher than enamel?
rougher
can dentin be removed with instrumentation?
yes
dentin is __________ so it gets its nutrients from the _____
avascular
pulp
the outer cells of the dental papilla form _________
ondontoblasts
what do ondontoblasts lay down?
predentin
ondontoblasts leave one long ___________ ___________ (tail) in the dentin
cytoplasmic extension
can apposition of dentin keep going? why?
yes because ondontoblasts live in the pulp
what are the two steps of maturation of dentin?
primary mineralization phase
secondary mineralization
(watercolor wash) as globules calcify, they expand and fuse together creating globular dentin
primary mineralization phase (dentin)
(watercolor blobs) as globules calcify, they expand but do not fuse completely. creates interglobular dentin that is less mineralized
secondary mineralization (dentin)
what is interglobular dentin?
the "space between the paint"
what are the five components of mature dentin?
ondontoblastic process
dentinal fluid
afferent axon
primary curvature
secondary curvature
extend from the DEJ to the outer wall of the pulp
dentinal tubules
the tail end of the ondontoblast (cell within the tubule)
ondontoblastic process
the tissue fluid surrounding the cell membrane of the ondontoblast (detects temp changes)
dentinal fluid
the nerve that receives sensation for the tooth, the nerve cell body is located in the pulp of the tooth
afferent axon
what two parts are left in the pulp?
nerve cell bodies and ondontoblasts
does the direction of the tubule reflect the pathway the ondontoblast took?
yes
overall tubule course which resembles a large S
primary curvature
small delicate curves showing the daily changes in ondontoblast direction during apposition (organic-living)
secondary curvature
what are the four types of dentin?
peritubular dentin
intertubular dentin
mantle dentin
circumpulpal dentin
the dentin that creates the dentinal tubule (walls of the "cave")
peritubular dentin
found between each of the tubules
intertubular dentin
first to form, closest to the DEJ (outside layer of the dentin)
mantle dentin
surrounds the pulp chamber
circumpulpal dentin
formed before the completion of the apical foramen. normal alignment of tubules and more calcified than secondary
primary dentin (virgin)
formed after the completion of the apical foramen. Less calcified than primary dentin. Formed to protect the pulp i.e. when an injury occurs, close to being a rct
secondary dentin
formed in response to trauma. irregular alignment of tubules because it is laid quickly. formed to protect the outer layer of dentin i.e. scaling too hard
tertiary dentin
because of trauma or age, the ondontoblastic process die and leave the tubule. the tubule is then filled with more dentin.
sclerotic dentin (part of tertiary dentin)
just like the incremental lines of retzius (dentin laid down cyclically)
inbrication lines of Von Ebner
darkened areas that show some sort of disturbance in apposition. the most pronounced is the _______ ____
contour lines of owen
neonatal line (most pronounced)
types of dentin are defined by _________ or ________ of formation
location
time
diameter of the tubules start to narrow as more dentin is laid and seals off the communication between the dentin and pulp. this is caused from:
age changes in dentin
what are the two clinical considerations with dentin?
the caries chute
hypersensitivity
since dentin is less calcifed, it is more prone to ________
caries
bacteria have been seen using the dentinal tubules as _______ towards the _____
chutes
pulp
why can a small cavity in the enamel be monitored, but once it has gotten to the dentin, it must be repaired asap?
because enamel is more calcified. once the bacteria gets to the dentin, it can use the dentinal tubules as a chute straight to the pulp
afferent axons are in the ________ _________
dentinal tubules
T/F afferent axons can differentiate between hot, cold, pressure, or dehydration?
false! they just translate all stimuli as PAIN
what is an active ingredient in sensodyne that can help diminish hypersensitivity?
potassium nitrate (blocks tubules by occluding)
tubules can be occluded with ________, laser treatments, and ________ ________.
fluoride
composite fillings (which sometimes secrete fluoride)
