exam 2: dentin Flashcards
makes up dentin
70% mineral (mainly calcium hydroxyapatite)
20% organic (mainly type I collagen)
10% water
type I collagen of dentin is slightly diff than bone
how:
type 1
higher ratio of proline and hydroxyproline
higher prevalence of molecular cross-linking
higher level of bound water
random orientation of hydroxyapatite crystals
dentin matrix non-collagenous proteins include:
- proteoglycans
- glycosaminoglycans
- carboxyglutamate- containing protein (gla-proteins)
- osteonectin
- osteopontin
biglycan
decorin
proteoglycans
chondroitin-4-sulfate
chondroitin-6-sulfate
glycosaminoglycans
contains receptor binding sequence arginine-glycine-asparagine aka RGD binding complex
osteopontin
order of dentin odontoblast life cycle
- pre-odontoblast
- secretory odontoblast
- transitional odontoblast
- resting odontoblast
stimulus for ectomesenchymal cell differentiation into Pre-Odontoblasts is derived from ________ located within the basal lamina of the IEE (inner enamel epithelium) and several growth factors derived from the IEE
fibronectin
pre-odontoblastic fibronectin receptors all the cells to align themselves along the _______, assume polarity, and differentiate into secretory cells
basal lamina
growth factors secreted by the IEE that play a roll in odontoblast differentiation include:
1
2
3
4
- TGF- transforming growth factor
- BMP- bone morphogenetic protein
- IGF- insulin-like growth factor
- FGF- fibroblast growth factor
compelte differentiation of odontoblasts requires a set number of ________which allows cells to express the right receptors to be able to bind growth factors to the IEE basal lamina
cell divisons
the last mitotic division results in a mature odontoblast and daughter cell that is forced into the
subodontoblastic cell layer
cells in subodontoblastic layer represent ectomesenchymal cells
this cell population is responsible for the ____odontoblasts that differentiate from PULPAL cells
reparative odontoblasts
in the secretory odontoblast stage, what 2 things form
-tall, columnar cells with extensive complex
-gap junctions
exhibits significant alkaline phosphatase activity
secretory odontoblast stage
secretory stage secretes
type 1 and traces of III and V collagen
what are the secrete matrix vesicles for secretory stage:
1
2
3
4
5
6
7
- phospholipids
- alkaline phosphatase
- phosphoproteins
- pyrohosphatase
- ca2+ and PO4-
- annexin
- calcium hydroxyapatite
- crystallites
mediates flow of Ca2+ into the matrix vesicle
-also serves as a collagen receptor that binds matrix vesicles to collagen
annexin
50-100um thick layer of first formed dentin
mantle dentin
matrix consists of both type I and II collagen
mantle dentin
how are collagen fibers in matrix of mantle dentin arranged
perpendicular to basal lamina of IEE
the organic matrix of dentin is deposited at rate of 4-8um per 24 hours.
-________________are thought to represent a hesitation in matrix formation and alters mineralization that occur after 4-20 days of matrix deposition
incremental lines in dentin (lines of von ebner)
deficiencies and irregularities in dentinogenesis, resulting in areas of hypermineralization, are common and appear as accentuated _____________________ or areas of interglobular dentin
incremental lines (neonatal line, contour lines of Owen)
dentinal tubules are tapered at the:
2.5 um diameter at the
1.2um diameter at the
0.9um near the
2.5 um diameter at the pupal surface
1.2um diameter at the midlength
0.9um near the DEJ
zone of globular (rather than linear) formed dentin in the crowns of teeth
characterized by interglobular spaces that are unmineralized or hypomineralized dentin between normal calcified dentinal layers
interglobular dentin
granular-appearing layer in dentin of root adjacent to the cementum.
possibly comprised of hypomineralized interglobular dentin
tome’s granular layer
all dentin (except mantle dentin) formed up to the time the tooth achieves functional occlusion
primary dentin
all dentin formed (except tertiary dentin) formed after tooth achieves functional occlusion
secondary dentin
dentinal tubules that are void of the ondotonoblastic process
-they are generally filled with air or organic debris and look black in transmitted light microscopy
dead tracts of dentin
dentin in which the tubules are occluded with mineral
-dentin in nontubular and is nearly TRANSPARENT
-incidence of occurrence increases with increasing age
-may also be tertiary (reparative) dentin
sclerotic dentin
the organic matrix of dentin is deposited in increments of 4um to 8um per 24 hours.
these occur after 4-20 days of matrix deposition and are thought to represent hesitations in matrix deposition and therefore altered mineralization
incremental lines of von ebner
(sideways lines)
both represent exaggerated lines of von ebner that occur during periods of altered cell metabolism
neonatal line and contour lines of owen
dentin deposited by newly differentiated odontoblasts at the site of pulpal trauma. a defensive reaction attempting to wall off the pulp from the site of injury (caries)
tertiary dentin (aka reparative dentin)
Cells in the ________ layer, once exposed to growth factors released by stimulated pulp cells differentiate and form the matrix of reparative dentin (teritary):
1
2
3
4
subodontoblastic layer
1. BMP- bone morphogenetic protein
2. IGF- insulin-like growth factor
3. FGF- fibroblast growth factor
4. DMP- dentin matrix protein
-hereditary defect that results in bluish-gray teeth with an opalescent sheen.
-the enamel is normal but chips off due to lack of support by the abnormal dentin.
-the pulp chamber and canals are generally obliterated by defective dentin formation
dentinogenesis imperfecta
loss of wear of surface caused by tooth to tooth contact during mastication or parafunction.
-matching wear on occluding surfaces and shiny facets on amalgam contacts are common.
-enamel and dentin wear is at the same rate
-possible fracture of cusps or restorations
attrition
loss of hard dental tissue by chemical processes
-broad concavities with cupping of occlusal surface and dentin exposure
-incisal translucency as well as wear on non-occluding surfaces
-amalgam restorations appear __________ and have non-tarnished appearance
-patients are usually hypersensitive
-very common with _____ patients
erosion
-raised
-GERD
dental caries.
many hydroxyapatite crystals exhibit a core of relatively more ___________ apatite.
The carbonate substitution in the lattice structure of enamel occurs primarily at: ___________
The core of this is eroded more favorably by acids due to its greater susceptibility to dissolution
soluble carbonate apatite
at phosphate sites
____ may substitute for hydroxyl ions in hydroxyapatite conferring greater stability and resistance to acidic dissolution
fluoride
bacteria responsible for dental caries include:
(1-4 enamel/dentin caries)
(5 root caries)
1
2
3
4
5
- streptococcus mutans
- streptocuccus sorbrinus
- streptocuccus gordonii
- lactobacillus acidophilius
- actinmyces (root)
as the process of dental caries reaches the DEJ it spreads laterally due to _________________ and then penetrates towards the pulp within these.
a substantial cavitation is produced beneath the adjacent enamel surface.
initially, the caries lesion exhibits a small opening or orifice in the enamel and pyramidal shaped dentin lesion with the apex of the pyramid pointing towards the __________
the branching of dentinal tubules at the DEJ
(within the dentinal tubules)
pointing towards the tooth pulp
1 in 5 adults suffer from dentinal _______
dentinal sensitivity
the teeth most commonly affected in dentinal sensitivity are
cuspids and bicuspids
stimuli associated with dentinal sensitivity include
- cold and hot drinks
- sweet or sour
- over brushing
- acidogenic plaque bacteria
- cosmetic bleaching
- clenching or bruxism
3 theories of dentinal sensitivity
- direct innervation theory
- transduction theory
- brannstrom’s hydrodynamic theory
direct stimulation of nerve endings in dentinal tubules
direct innervation theory
stimulation of odontoblasts that are coupled to nerves in the pulp
transduction theory
stimulation of dentinal tubules or exposed odontoblastic cell processes causes movement of tissue fluids within dentinal tubules that stimulate nerve endings in close assoc. with dentin at dentin/pulp interface
brannstrom’s hydrodynamic theory
brannstrom’s hydrodynamic theory
if heat is applied to sens tooth, the volume of the fluid in the tubules ________, causing stimulation of the nerve endings.
cold would have a similar effect as the volume of fluid would _______ still causing a movement in the fluid and stimulation of the nerve endings
heat-increases
cold-decreases
this theory has roots in charles law-> volume of a gas/fluid is directly proportional to the amount of heat applied at constant pressure
brannstrom’s hydrodynamic theory
