dentin

Question 1

dentin is ____% mineral by volume and ____% organic matrix by volume

Answer 1

50; 30

Question 2

of the organic matrix of dentin, about 90% is _____ by weight

Answer 2

collagen-I

Question 3

90% of the non-collagenous protein of dentin is derived from _____

Answer 3

DSPP (dentin sialophosphoprotein)

Question 4

other components of dentin:

Answer 4

dentin matrix protein (DMP1)
osteonectin (SPARC)
bone sialoprotein (BSP)
osteopontin (OPN)
proteoglycans

Question 5

odontoblasts differentiate from _____

Answer 5

dental papilla cells

Question 6

a long cytoplasmic extension encased in dentin

Answer 6

odontoblastic process

Question 7

rate of deposition of dentin

Answer 7

about 4 micrometers/day

Question 8

incremental (daily) lines in dentin are called:

Answer 8

incremental lines of Owen (or von Ebner)

Question 9

dentin formation occurs throughout life, reducing the sizes of the ____ and ____

Answer 9

pulp chambers; root canals

Question 10

microscopic zones in the pulp

Answer 10

odontoblastic layer (beneath the dentin)
cell-free zone (nerve and capillary plexus)
cell-rich zone (extensive vascular system)
pulpal core

Question 11

lines of von Ebner are oriented in the ____ axis at approx ____ angles to the dentinal tubules which run in the ____ axis

Answer 11

horizontal; right; vertical

Question 12

dentin tubules contain ____ which mediate dentin sensitivity

Answer 12

odontoblastic processes

Question 13

more terminal branching of dentinal tubules occurs in ____ compared to ____

Answer 13

root dentin; coronal dentin

Question 14

_____ have an S-shaped curvature

Answer 14

coronal tubules

Question 15

dentin tubules are ____ in diameter

Answer 15

1 to 3 micrometers

Question 16

more dentin tubules are in the ____ relative to the ____

Answer 16

crown; root

Question 17

more dentin tubules are near the ____ than the ____

Answer 17

pulp; surface

Question 18

the fibrillar organic matrix before its calcification

Answer 18

predentin

Question 19

odontoblasts exhibit a ____ shape, with their nucleus at the ____ region

Answer 19

tall columnar; basal

Question 20

predentin is always interposed between the ____ and the _____

Answer 20

odontoblasts; mineralizing front

Question 21

dentin made during tooth formation

Answer 21

primary dentin

Question 22

primary dentin is also called _____; makes up most of the tooth; outer layer is called _____

Answer 22

circumpulpal dentin; mantle dentin

Question 23

forms by the slower, continuing deposition of dentin by odontoblasts following completion of the root

Answer 23

secondary dentin

Question 24

junction betw primary and secondary dentin is characterized by a change in the ______

Answer 24

direction of dentinal tubules

Question 25

deposition of secondary dentin is fastest on the ____ and _____ of the _____, leading to pulp recession

Answer 25

roof; floor; pulp chamber

Question 26

local reaction to attrition, caries, or dental restoration

Answer 26

tertiary dentin

Question 27

subtypes of tertiary dentin

Answer 27

reactionary dentin and reparative dentin

Question 28

reactionary dentin (least severe) is formed by ____

Answer 28

preexisting odontoblasts

Question 29

reparative dentin is formed by newly differentiated _____; these cells can be included in the hard tissue, which is called _____

Answer 29

odontoblast-like cells; osteodentin

Question 30

dentin that has become translucent due to calcification of the dentinal tubules as a result of normal aging or injury; also called _____

Answer 30

sclerotic dentin; transparent dentin

Question 31

patterns of dentin mineralization

Answer 31

linear or globular

Question 32

____ occurs at high rates of dentin deposition; best seen in the mantle dentin

Answer 32

globular mineralization

Question 33

globular mineralization results in an irregular mineralization front at the _____ interface

Answer 33

predentin-dentin

Question 34

localized areas of hypomineralized dentin, often just beneath the mantle dentin, where globular zones of mineral fail to fuse into a homogeneous mass

Answer 34

interglobular dentin

Question 35

interglobular dentin can be caused by ____ and _____

Answer 35

decreased vitamin D ; high fluoride

Question 36

dentinal tubules pass through interglobular dentin, but ____ dentin is not present in these areas

Answer 36

peritubular

Question 37

peritubular dentin (PTD) is lower in ____, higher in ____, and more highly ____ than intertubular dentin (ITD)

Answer 37

collagen; DSPP; mineralized

Question 38

where is ITD harder?

Answer 38

ITD is harder at the DEJ than at the pulp (about 4x)

Question 39

where is PTD harder?

Answer 39

PTD has equal hardness at DEJ and pulp

Question 40

is PTD or ITD harder?

Answer 40

PTD is harder than ITD at both the pulp (about 20x) and the DEJ (about 5x)

Question 41

odontoblasts line the ___ surface of dentin

Answer 41

pulpal

Question 42

the dental phenotype in persons afflicted with osteogenesis imperfecta

Answer 42

dentinogenesis imperfecta type I (DGI-I)

Question 43

mutations in the ____ and _____ genes cause osteogenesis imperfecta

Answer 43

COL1A1; COL1A2

Question 44

COL1A1 and COL1A2 mutations can:

Answer 44

1. reduce the amount of collagen (less severe phenotype) | 2. produce defective collagen molecules (more severe phenotype)

Question 45

COL1A1 gene mutation causes _____ osteogenesis imperfecta

Answer 45

autosomal-dominant

Question 46

classic radiographic features of DGI-I (dental phenotype of someone with osteogenesis imperfecta)

Answer 46

bulbous crowns, pulpal obliteration, short roots, and tooth impactions

Question 47

mutations in DSPP cause:

Answer 47

DD-II (dentin dysplasia type II) DGI-II DGI-III

Question 48

2 structural domains of DSPP

Answer 48

``` dentin sialoprotein (DSP) - proteoglycan dentin phosphoprotein (DPP)- acidic protein ```

Question 49

expression of DSPP in teeth

Answer 49

expressed in preameloblasts, preodontoblasts, and odontoblasts

Question 50

Dspp (-/-) mice show features similar to human ____

Answer 50

DGI-III

Question 51

dspp (-/-) mice show enlarged ____, reduced thickness of ____ and increased thickness of ____ (similar to human DGI-III)

Answer 51

pulp cavities; mineralized dentin; predentin

Question 52

____ is distinct from OI as only the teeth are affected; caused by mutations in DSPP

Answer 52

DGI-II