enamel tissue

Question 1

enamel is ____ % by weight inorganic substance

Answer 1

96%

Question 2

principal mineral component is ____; enamel crystals, compared to other 3 mineralized tissues, are ___ and consist of more ____

Answer 2

calcium hydroxyapatite; larger; impurities (fluoride, carbonate)

Question 3

enamel is ___% by weight organic substance

Answer 3

1%

Question 4

the highest percentage (90%) of the organic substance of enamel is composed of ____, a seed protein for normal mineralization

Answer 4

amelogenin

Question 5

____ makes up 3% by weight of enamel

Answer 5

water

Question 6

DEJ configuration is ____ in the coronal area for adaptation to occlusal forces

Answer 6

scalloped

Question 7

DEJ configuration is ____ in cervical areas (non-load bearing areas)

Answer 7

smooth

Question 8

ameloblasts are _____ epithelial cells

Answer 8

columnar

Question 9

the ____ of the tooth germ gives rise to ameloblasts

Answer 9

inner epithelial layer

Question 10

growth lines of enamel are called _____

Answer 10

growth lines or striae of Retzius

Question 11

4 mineralized tissues of the body

Answer 11

enamel (the hardest)
dentin
cementum
bone

Question 12

growth lines of dentin, cementum, and bone

Answer 12

dentin- von Ebner
cementum- lines of Slater
bone- lamellae

Question 13

____ are numerous small transverse ridges on the exposed surfaces of enamel

Answer 13

perikymata

Question 14

_____ end on the enamel surface as grooves; _____ are created between the grooves

Answer 14

striae or lines of Retzius; ridges (Perikymata)

Question 15

each perikymata is thought to take approx ____ to form

Answer 15

8-10 days

Question 16

perikymata are found on all permanent teeth, but are usually most noticeable on _____

Answer 16

canines

Question 17

the structures of enamel are due to the ___ and ___ of the apatite crystals in each site

Answer 17

direction; density

Question 18

structural unit of enamel

Answer 18

enamel rods

Question 19

an enamel rod has a diameter of ____ and a length of up to ____

Answer 19

5-6 micrometers; 2.5 mm

Question 20

each rod is formed by ____

Answer 20

one ameloblast

Question 21

outer surface of the rod

Answer 21

enamel sheath

Question 22

the highest percentage of organic material in the enamel sheath

Answer 22

amelin

Question 23

lies between the sheaths of the rods

Answer 23

interrod substance

Question 24

_____ secrete the interrod substance

Answer 24

two or more ameloblasts

Question 25

crystal density and direction in enamel rod, sheath and interrod substance

Answer 25

rod: hydroxyapatite crystals are most dense in the center or core of the rod and run parallel to the long axis of the rod sheath: less dense than core and run in different direction; higher % of organic substance interrod: more dense than in sheath and run in different directions

Question 26

each ameloblast secretes ____ and two or more ameloblasts secrete the _____

Answer 26

one rod and its sheath; interrod substance

Question 27

rest period of an ameloblast is marked by an _____; a rod is segmented because it is secreted in a ____ manner

Answer 27

interrod striation; rhythmic

Question 28

enamel rods are at ____ to the dentin surface

Answer 28

right angles

Question 29

extend for varying depths from the surface of enamel and consist of linear, longitudinally oriented defects filled with enamel protein or organic debris from the oral cavity

Answer 29

``` enamel lamellae (extend toward dentin, may enter dentin and pass to pulp) ```

Question 30

clinical significance of enamel lamellae

Answer 30

``` access by acidophilic microorganisms (caries) stain substances (esthetic considerations) ```

Question 31

tufts contain a greater concentration of _____ than the rest of the enamel

Answer 31

enamel protein (tuftelin)

Question 32

enamel spindles originate from cell processes of _____ that become embedded in newly secreted enamel

Answer 32

odontoblasts

Question 33

originate at DEJ and pass into enamel

Answer 33

enamel tufts

Question 34

originate in dentin, pass DEJ into enamel

Answer 34

enamel spindles

Question 35

enamel tufts and spindles contribute to:

Answer 35

the spread of caries along the DEJ

Question 36

Alternating dark and light bands (layers) of varying width: Originate at the DEJ border and pass outward ending at some distance from the outer enamel surface

Answer 36

Hunter-Schreager bands

Question 37

what are Hunter-Schreager bands caused by?

Answer 37

different direction of enamel rods in adjacent layers

Question 38

change in enamel rod direction is regarded as a _____, minimizing the risk of ____ in the ____ direction under the influence of masticatory forces. clinically significant when performing operative dentistry

Answer 38

functional adpatation; cleavage; apical

Question 39

ectopic enamel formation is called an _____

Answer 39

enamel pearl

Question 40

intrinsic stain caused by what antibiotic

Answer 40

tetracycline

Question 41

what causes mulberry molar?

Answer 41

congenital syphilis

Question 42

tooth within a tooth

Answer 42

dens in dente

Question 43

an omnivorous fish native to the Amazon river basin in South America and notable for its uncanny mouth of human-like teeth; the species is a close cousin of the piranha

Answer 43

pacu