QUIZ 3 Dentin Pulp Complex I Flashcards
dentin is the main ___ material of the tooth
structural
the structure of the dentin is directly linked to what?
its primary function of supporting tooth loading
briefly describe enamel, dentin, and pulp
- enamel
- mineralized protective component
- dentin
- mineralized structural component
- pulp
- main cellular component
dentin is highly analogous to ___, but slightly different composition and highly different anatomy
bone
the crown is covered by ___, and the root is covered by ___
- enamel
- cementum
dentin is ___% inorganic material, ___% organic material, and ___% water
70%, 20%, 10%
hydroxyapatite makes up the ___ component of dentin
inorganic material
what is the formula for hydroxyapatite, and how many molecules of HA are in each crystal unit cell?
Ca5(PO4)3(OH)
2 per crystal unit cell
HA is effectively a ___ ___ crystal
calcium phosphate
fluoride can replace the ___ in hydroxyapatite, creating ___
- OH
- fluoroapatite
besides fluoride, what else can replace the OH in hydroxyapatite in dentin?
zinc, magnesium, and others
in dentin, HA crystals are what shape?
flattened rectangular plates
what are the dimensions of HA in dentin?
- 60-70 nm long
- 20-30 nm wide
- 3-4 nm thick
dentin is somewhat harder than ___. what are the knoop numbers for dentin, enamel, and bone?
- bone
- knoop numbers:
- dentin - 68
- enamel - 343
- cortical bone - 50
what is the composition of the organic material component of dentin?
- 90% collagen
- mostly I, some III and V
- 10% non-collagenous proteins
describe the collagen component of the organic component of dentin
- 90%
- mostly collagen I, some III and V
- fibrillar collagen scaffold upon which HA crystals are laid down
what are the 5 non-collagenous proteins that dentin has in common with bone?
- bone sialoprotein (BSP)
- osteopontin (OP)
- osteocalcin (OC)
- osteonectin (ON)
- matrix extracellular phosphoglycoprotein
what are the 2 main dentin specific non-collagenous proteins?
- dentin matrix protein-1 (DMP-1)
- dentin sialophosphoprotein (DSPP)
- *still found in bone, but only trace amounts
DSPP can be further cleaved into what 3 functional proteins?
- dentin sialoprotein (DSP)
- dentin phosphoprotein (DPP)
- dentin glycoprotein (DG)
DSPP is cleaved rapidly by what enzyme?
BMP-1
describe DSP
- proteoglycan
- expressed in dentinal tubules
- may act to prevent mineralization
- similar to DMP-1
describe DGP
- glycoprotein
- role in biomineralization?
- unknown function
describe DPP
- binds lots of calcium, initiates HA formation
- attached to collagen
- not thought to be glycosylated
DSP comes from which end of DSPP?
N terminus
DPP comes from which end of DSPP?
C terminus
defects in DSPP can cause what?
dentinogenesis imperfecta types II and III
which dentinogenesis imperfecta type is described by the following:
results from OI (defect in collagen I), pulp chambers filled with abnormal dentin
type I (not a result of defects in DSPP)
which dentinogenesis imperfecta type is describe by the following?
not associated with osteogenesis imperfecta (DSPP defect), pulp chambers filled with abnormal dentin
type II
which dentinogenesis imperfecta type is describe by the following?
enlarged pulp chambers, hypo-mineralization, possibly failure of DSPP expression
type III
dentin is synthesized by ___, which line the pulp chamber
odontoblasts
odontoblasts have a ___ origin
mesenchymal
odontoblasts are ___ cells which extend cellular projections into the dentin through ___
- polarized
- tubules
label this photo
the dentin-pulp complex arises from ___
dental papilla
in the development of dentin, odontoblasts differentiate and fill what?
the acellular zone between the IEE and dental papilla
is there vascular support for odontoblasts?
yes
in the development of dentin, initial differentiation involves the critical interaction with the ___
IEE
the ___ is the interface betwen the enamel and dentin, where they are in direct apposition
DEJ
the DEJ has a ___ edge
scalloped
why is the shape (scalloped) of the DEJ critical?
- defines the shape of the crown
- keeps dentin directly attached to enamel during loading (no shearing)