dentin essentials

Question 1

dentin location

Answer 1

in crown and root

Question 2

dentin structure

Answer 2

tubular - microcanals radiate from dental pulp to enamel

Question 3

dentin color

Answer 3

yellow

Question 4

percentage mineralized inorganic substrates - calcium hydroxyapatite

Answer 4

65-70%

Question 5

percentage organic substrates - collagenous protein

Answer 5

20-25%

Question 6

percentage bound water

Answer 6

10%

Question 7

Tomes fiber

Answer 7

vital tissue; cytoplasmic cell process

odontoblast process (an extension of an odontoblast- located in the dentinal tubules)

Question 8

odontoblast

Answer 8

vital tissue; innervation to pulp

Question 9

types of nerve fibers

Answer 9

myelinated A-fibers

unmyelinated C-fibers

Question 10

Tomes layer

Answer 10

peripheral layer

cytoplastic process

Question 11

Hyaline of Hopewell-Smith

Answer 11

clear layer between Tomes layer and cementum

Question 12

cementum composition

Answer 12

45-50% inorganic (hydroxyapatite)

5-55% organic and water (collagen and proteoglycans)

Question 13

cementum

Answer 13

thin layer (30-200 micrometers) of bonelike

material covering root surfaces
softer than enamel and dentin

fibers of periodontal membrane-ligament are connected to cementum

Question 14

Lines of Owen

Answer 14

disturbance during mineralization

Question 15

loss of cementum

Answer 15

exposed dentin

Question 16

dentin tubules

Answer 16

primary curvature & secondary curvature

result from movement of odontoblasts during development

Question 17

primary curvature

Answer 17

s-shaped

Question 18

secondary cuvature

Answer 18

jagged or wrinkled texture

Question 19

s-shaped

Answer 19

tooth crown

Question 20

straighter path of tubules

Answer 20

root of tooth

Question 21

primary dentin

Answer 21

most prominent dentin

lies between the enamel and pulp chamber starting at the dentinoenamel junction

Question 22

mantle-dentin

Answer 22

the first formed dentin by odontoblast differentiation; it is located in both the crown underlying the DEJ and the root of the tooth

Question 23

circumpulpal dentin

Answer 23

remaining bulk of primary dentin; collagen fibers narrower and thicker than M-D; greater mineralization than M-D; compact arrangement of fibers

Question 24

secondary dentin

Answer 24

all dentin formed after root formation is completed (not due to trauma or dental pathology) - closest to pulp (visible on dental radiographs)

forms at slower rate than primary dentin but grows incrementally but unequally

Question 25

what happens when tooth ages

Answer 25

secondary dentin grows, narrowing pulp chamber

Question 26

tertiary dentin

Answer 26

dentin formed as reaction to external stimulation (pathologic)
response to trauma

can cause narrowing of pulp chambers and root canals

Question 27

reactionary tertiary dentin

Answer 27

formed from preexisting odontoblast

Question 28

reparative tertiary dentin

Answer 28

formed from newly differentiated odontoblasts

Question 29

sclerotic dentin

Answer 29

tertiary dentin

• depositied in response to trauma
• more mineralized - tubules diameter narrows
• less permeable
• difficult to bond