Histology: Enamel, Dentin & Pulp

Front 1

What is the hardest substance in the body? Why?

Back 1

enamel; arrangement of hydroxyapaptite crystals

Front 2

Enamel is especially brittle due to the high ___________ content and requires the support of _______ to prevent breaking.

Back 2

inorganic; dentin

Front 3

Enamel is slight permeable to __________

Back 3

saliva

Front 4

proteins of saliva on the surface of enamel that protect against acid and bacterial attachment and growth)

Back 4

acquired pellicle

Front 5

What are the chemical properties of enamel?

Back 5

95% inorganic
4% organic

Front 6

What is the inorganic composition of enamel?

Back 6

(95%) hydroxyapatite crystals

Front 7

Hydroxyapaptite crystals of enamel ________ with age and therefore decrease the risk of crown caries and increase the risk of root caries.

Back 7

enlarge

Front 8

What is the organic composition of enamel (three enamel matrix proteins)?

Back 8

constitutes 4% of enamel

1. amelogenin
2. ameloblastin
3. enamelin

Front 9

Which enamel matrix protein is associated with hypoplastic amelogenesis imperfecta?

Back 9

enamelin

Front 10

Which enamel matrix protein is only found on the mineralization front beneath the secretory face of Tomes process?

Back 10

enamelin

Front 11

Which enamel matrix protein is found in the rod sheath?

Back 11

ameloblastin

Front 12

Which enamel matrix protein is postulated to assist ameloblasts in adhering to the forming enamel surface during secretory phase?

Back 12

ameloblastin

Front 13

Which enamel matrix protein is tooth specific and is secreted by ameloblasts, odontoblasts, and cementoblasts?

Back 13

amelogenin

Front 14

Which enamel matrix protein appears as small nanospheres which regulate spacing of hydroxyapatite crystals, keeping them thin?

Back 14

amelogenin

Front 15

Which enamel matrix protein is the most prevalent?

Back 15

amelogenin

Front 16

Which enamel matrix protein is least prevalent?

Back 16

enamelin

Front 17

hydroxyapatite crystals in the head of the enamel rod (prism) are arranged ________________ to the long axis of the enamel rod.

Back 17

longitudinally

Front 18

hydroxyapatite crystals in the tails of the enamel rods (which are secreted first) are oriented at a ____ degree angle off the long axis

Back 18

65 degree

Front 19

hypomineralized sheath surrounding each enamel rod (prism)

Back 19

rod sheath

Front 20

twisted rods of enamel under cuspal tips that provide strength and resistile strength against occlusal forces; represents path of enamel rods as they retreat from DEJ

Back 20

gnarled enamel

Front 21

ameloblasts retreat in a direction ___________ to the DEJ and twist to the left and right (forming an 's' shape) while secreting ____________.

Back 21

perpendicular; enamel

Front 22

What are the three banding patterns produced by the orientation of enamel rods?

Back 22

1. striae of retzius
2. neonatal line
3. hunter-schreger bands

Front 23

banding pattern visable in enamel only with reflected light; result from arrangement of hydroxyapatite cyrstals

Back 23

hunter-schreger bands

Front 24

concentric dark bands that follow the contour of the tooth; hypomineralized areas of rods resulting from growth over several days during periods of physiological stress

Back 24

striae of retzius

Front 25

horizontal grooves on the surface of the tooth; surface manifestations of the striae of retzius

Back 25

perikymata

Front 26

fusion lines between 2 cusp growth centers

Back 26

fissure

Front 27

area where two fissures cross

Back 27

pit

Front 28

enamel over pits and fissures is _________ and _____ protective

Back 28

thinner; less

Front 29

appear as dark lines extending from the DEJ to the surface; hypo mineralized (dark) lines that represent cracks in enamel caused by stress that is filled in and mineralized; especially weak to organic acids

Back 29

enamel lamellae

Front 30

optical effect caused by the movement of ameloblasts from the DEJ; tufts of grass; hypomineralized

Back 30

enamel tufts

Front 31

odontoblastic cell processes that crossed over the DEJ and are embedded in enamel ; responsible for sensitivity of tooth near the DEJ

Back 31

enamel spindles

Front 32

What is the order of both hardness and density for the hard tissues of the mouth/body?

Back 32

enamel, dentin, cementum=bone

Front 33

bone and ___________ are of equal hardness and density

Back 33

cementum

Front 34

What is the chemical composition of dentin?

Back 34

20% organic (collagen and glycosaminoglycans)
67% inorganic (hydroxyapatite)
13% water

Front 35

channel through dentinal matrix that contains odontoblastic cell processes

Back 35

dentinal tubules

Front 36

Where are dentinal tubules more concentrated per unit area?

Back 36

near pulp

Front 37

Dentinal tubules are ________ and more abundant near the __________. Odontoblastic cell processes are _______ thicker and more ________ near pulp.

Back 37

larger; pulp

thicker; numerous

Front 38

___________ ___________ induces the formation of ameloblasts

Back 38

mantle dentin

Front 39

peritubular dentin immediately surrounding the odontoblastic cell processes is _______________

Back 39

hypercalcified

Front 40

the junction between peritubular and intertubular dentin

Back 40

sheath of neuman

Front 41

daily depositions of dentinal matrix; hypomineralized lines perpendicular to the dentinal tubules; equivalent to daily striations of rod segments of enamel

Back 41

incremental lines of von ebner

Front 42

found in root along DCJ (only in root); small hypomineralized spheres that represent the highly branched terminal ends of odontoblastic cell processes

Back 42

granular layer of Tomes

Front 43

the type of dentin produced in response to insult; odontoblasts form a patch of dentin to protect tubules; hypomineralized matrix

Back 43

tertiary dentin

Front 44

area of empty dentinal tubules resulting from bacterial invasion; odontoblastic cell processes retreat; region looks black with sclerotic dentin beneath

Back 44

dead tracts

Front 45

hypercalcified dentin under dead tract that forms a protective barrier and appears white

Back 45

sclerotic dentin

Front 46

When is pulp formed?

Back 46

When dental papilla becomes dentin

Front 47

What controls whether a tooth will be incisor or molar?

Back 47

the dental papilla after bud stage

Front 48

the cell-rich zone of the pulp contains what?

Back 48

fibroblasts and stem cells

Front 49

What is the subodontoblastic plexus of Raschkow?

Back 49

nerve plexus in the pulp containing afferent fibers for pain

Front 50

The pulp reduces in size due to the continual addition of ________ _________

Back 50

secondary dentin

Front 51

with age, the number of fibroblasts and defense cells ________, and the number of collagen fibers and thickness ______________

Back 51

decreases, increases