exam 2: dentin

Question 1

makes up dentin

Answer 1

70% mineral (mainly calcium hydroxyapatite)
20% organic (mainly type I collagen)
10% water

Question 2

type I collagen of dentin is slightly diff than bone
how:

Answer 2

type 1
higher ratio of proline and hydroxyproline
higher prevalence of molecular cross-linking
higher level of bound water
random orientation of hydroxyapatite crystals

Question 3

dentin matrix non-collagenous proteins include:

Answer 3

1. proteoglycans
2. glycosaminoglycans
3. carboxyglutamate- containing protein (gla-proteins)
4. osteonectin
5. osteopontin

Question 4

biglycan
decorin

Answer 4

proteoglycans

Question 5

chondroitin-4-sulfate
chondroitin-6-sulfate

Answer 5

glycosaminoglycans

Question 6

contains receptor binding sequence arginine-glycine-asparagine aka RGD binding complex

Answer 6

osteopontin

Question 7

order of dentin odontoblast life cycle

Answer 7

1. pre-odontoblast
2. secretory odontoblast
3. transitional odontoblast
4. resting odontoblast

Question 8

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

Answer 8

fibronectin

Question 9

pre-odontoblastic fibronectin receptors all the cells to align themselves along the _______, assume polarity, and differentiate into secretory cells

Answer 9

basal lamina

Question 10

growth factors secreted by the IEE that play a roll in odontoblast differentiation include:
1
2
3
4

Answer 10

1. TGF- transforming growth factor
2. BMP- bone morphogenetic protein
3. IGF- insulin-like growth factor
4. FGF- fibroblast growth factor

Question 11

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

Answer 11

cell divisons

Question 12

the last mitotic division results in a mature odontoblast and daughter cell that is forced into the

Answer 12

subodontoblastic cell layer

Question 13

cells in subodontoblastic layer represent ectomesenchymal cells
this cell population is responsible for the ____odontoblasts that differentiate from PULPAL cells

Answer 13

reparative odontoblasts

Question 14

in the secretory odontoblast stage, what 2 things form

Answer 14

-tall, columnar cells with extensive complex
-gap junctions

Question 15

exhibits significant alkaline phosphatase activity

Answer 15

secretory odontoblast stage

Question 16

secretory stage secretes

Answer 16

type 1 and traces of III and V collagen

Question 17

what are the secrete matrix vesicles for secretory stage:
1
2
3
4
5
6
7

Answer 17

1. phospholipids
2. alkaline phosphatase
3. phosphoproteins
4. pyrohosphatase
5. ca2+ and PO4-
6. annexin
7. calcium hydroxyapatite
8. crystallites

Question 18

mediates flow of Ca2+ into the matrix vesicle
-also serves as a collagen receptor that binds matrix vesicles to collagen

Answer 18

annexin

Question 19

50-100um thick layer of first formed dentin

Answer 19

mantle dentin

Question 20

matrix consists of both type I and II collagen

Answer 20

mantle dentin

Question 21

how are collagen fibers in matrix of mantle dentin arranged

Answer 21

perpendicular to basal lamina of IEE

Question 22

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

Answer 22

incremental lines in dentin (lines of von ebner)

Question 23

deficiencies and irregularities in dentinogenesis, resulting in areas of hypermineralization, are common and appear as accentuated _____________________ or areas of interglobular dentin

Answer 23

incremental lines (neonatal line, contour lines of Owen)

Question 24

dentinal tubules are tapered at the:
2.5 um diameter at the
1.2um diameter at the
0.9um near the

Answer 24

2.5 um diameter at the pupal surface
1.2um diameter at the midlength
0.9um near the DEJ

Question 25

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

Answer 25

interglobular dentin

Question 26

granular-appearing layer in dentin of root adjacent to the cementum. possibly comprised of hypomineralized interglobular dentin

Answer 26

tome's granular layer

Question 27

all dentin (except mantle dentin) formed up to the time the tooth achieves functional occlusion

Answer 27

primary dentin

Question 28

all dentin formed (except tertiary dentin) formed after tooth achieves functional occlusion

Answer 28

secondary dentin

Question 29

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

Answer 29

dead tracts of dentin

Question 30

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

Answer 30

sclerotic dentin

Question 31

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

Answer 31

incremental lines of von ebner (sideways lines)

Question 32

both represent exaggerated lines of von ebner that occur during periods of altered cell metabolism

Answer 32

neonatal line and contour lines of owen

Question 33

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)

Answer 33

tertiary dentin (aka reparative dentin)

Question 34

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

Answer 34

subodontoblastic layer 1. BMP- bone morphogenetic protein 2. IGF- insulin-like growth factor 3. FGF- fibroblast growth factor 4. DMP- dentin matrix protein

Question 35

-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

Answer 35

dentinogenesis imperfecta

Question 36

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

Answer 36

attrition

Question 37

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

Answer 37

erosion -raised -GERD

Question 38

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

Answer 38

soluble carbonate apatite at phosphate sites

Question 39

____ may substitute for hydroxyl ions in hydroxyapatite conferring greater stability and resistance to acidic dissolution

Answer 39

fluoride

Question 40

bacteria responsible for dental caries include: (1-4 enamel/dentin caries) (5 root caries) 1 2 3 4 5

Answer 40

1. streptococcus mutans 2. streptocuccus sorbrinus 3. streptocuccus gordonii 4. lactobacillus acidophilius 5. actinmyces (root)

Question 41

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 __________

Answer 41

the branching of dentinal tubules at the DEJ (within the dentinal tubules) pointing towards the tooth pulp

Question 42

1 in 5 adults suffer from dentinal _______

Answer 42

dentinal sensitivity

Question 43

the teeth most commonly affected in dentinal sensitivity are

Answer 43

cuspids and bicuspids

Question 44

stimuli associated with dentinal sensitivity include

Answer 44

1. cold and hot drinks 2. sweet or sour 3. over brushing 4. acidogenic plaque bacteria 5. cosmetic bleaching 6. clenching or bruxism

Question 45

3 theories of dentinal sensitivity

Answer 45

1. direct innervation theory 2. transduction theory 3. brannstrom's hydrodynamic theory

Question 46

direct stimulation of nerve endings in dentinal tubules

Answer 46

direct innervation theory

Question 47

stimulation of odontoblasts that are coupled to nerves in the pulp

Answer 47

transduction theory

Question 48

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

Answer 48

brannstrom's hydrodynamic theory

Question 49

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

Answer 49

heat-increases cold-decreases

Question 50

this theory has roots in charles law-> volume of a gas/fluid is directly proportional to the amount of heat applied at constant pressure

Answer 50

brannstrom's hydrodynamic theory