Oral Biology > QUIZ 2 Enamel II > Flashcards

QUIZ 2 Enamel II Flashcards

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1
Q

rods and interrod enamel geometry are directly linked to the geometry of what?

A

the individual ameloblasts

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2
Q

rods are continuous from the ___ to the ___

A

inner enamel to the outer enamel

*uniform enamel at the innermost and outermost; no rods

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3
Q

describe the orientation of rods in relation to one another

A

inner 2/3 is somewhat interwoven, and the outer 1/3 is much straighter

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4
Q

the distal end of tomes’ process directly forms what?

A

1 enamel rod (and surrounding interrod enamel)

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5
Q

___ is formed first, and makes a pit into which the ___ is synthesized

A
  • interrod enamel
  • enamel rod
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6
Q

dentin forms inwards, towards the ___

A

pulp

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7
Q

the ___ deliminates the surface area of the enamel

A

DEJ

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8
Q

enamel is formed ___ as a cap; the dentin is formed ___, making up most of the tooth body

A
  • outwards
  • inwards
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9
Q

is enamel formation simultaneous?

A

no; it forms apically

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10
Q

as the crown grows, there are new ameloblasts that come into play ___

A

cervically

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11
Q

which enamel proteins are responsible for enamel deposition?

A

ameloginins, ameloblastin, enamelin

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12
Q

which enamel proteins are involved in organic component degradation?

A

enamelysin, enamel matrix serine protease (kallikrein 4)

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13
Q

which enamel proteins are involved the basal lamina during maturation?

A

amelotin, odontogenic ameloblast associated protein (ODAM)

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14
Q

which protein is the main protein family in developing enamel (80-90%) and is only expressed while enamel is being produced; it restricts lateral HA crystal growth, preventing crustal fusion. the loss of function of this protein = no enamel rods

A

amelogenins

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15
Q

which protein is around 10% of the enamel organic content, is expressed all the way through to maturation, involves ameloblast adhesion to developing enamel, and its loss of function results is ameloblasts falling off (no enamel)?

A

ameloblastin

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16
Q

which protein is the least abundant (<5%) enamel protein (but largest), is only present at the leading edge of enamel deposition, and whose function is possibly crystal elongation; loss of function = no enamel

A

enamalin

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17
Q

which enamel protein is an MMP (MMP 20), is found during enamel deposition, chops up ameloblastin and enamelin; loss of function results in thin immature enamel, and is critical for the removal of organic component to allow increased mineralization?

A

enamelysin

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18
Q

which enamel protein is secreted during modulation events of enamel maturation, degrades amelogenins, and the loss of function results in immature enamel?

A

enamel matrix serine protease

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19
Q

the basal lamina doesn’t seem to contain much, if any, ___, but instead has a variety of other proteins, including ___ and ___

A
  • collagen IV
  • ODAM and amelotin
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20
Q

describe how enamel acid etching is important clinically

A
  • fissure sealants
  • bonding restorative materials to enamel
  • cementing orthodontic materials to enamel
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21
Q

describe how enamel acid etching provides better bonding surface

A
  • it increases the porosity of enamel surface (infiltration of material into tissue)
  • also removes any debris clinging to the enamel surface
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22
Q

the mechanism of enamel acid etching is similar to ___

A

microbial incursions (acid attack)

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23
Q

enamel acid etching is accomplished by dissolving ___

A

enamel crystals

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24
Q

describe enamel etching

A
  • carbonated apatite in crystal core
    • more prevalent and vulnerable in inner enamel
  • crystal ends are first to dissolve, then along core
  • effectively dissolves from the inside out
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25
etching enamel doesn't always produce the same effect on the \_\_\_
surface
26
what are the 3 possible patterns of acid etching?
* type I - most common * preferential removal of rods * type II - reverse of type I * interrod enamel removed * type III - least frequent * irregular and indiscriminate pattern
27
the three possible etching patterns are most likely due to a difference in what?
* the orientation of rod vs interrod enamel crystals - acid etched surface enamel * rod crystal ends are perpendicular to enamel surface * interrod crystal ends not generally exposed
28
what is attrition?
tooth wear
29
enamel is non-vital, meaning what?
it cannot be replaced (no more ameloblasts)
30
attrition of enamel may expose \_\_\_
dentin
31
in the attrition of enamel, what might be eliminated?
topographical features, like pits and fissures
32
what are the 3 types of attrition?
abrasion, abfraction, and erosion
33
what is abrasion?
removal of enamel by abrasive force (ex. aggressive brushing)
34
what is abfraction?
notch-like cervical lesions caused by cyclic loading of teeth which places stress on the interrod-rod interface, causing rods to separate
35
what is erosion?
removal of enamel by break down of crystals (acid)
36
describe how enamel color changes with age
* darkness increases with age * thins with age * extrinsic staining
37
describe how the nature of the enamel surface layer changes with age
* changes due to ionic exchange from oral environment * fluoride ion most prevalent - topical application
38
describe how enamel water content changes with age
water content decreases with age as crystals enlarge and decrease pore size
39
describe how enamel brittleness changes with age
brittleness increases with age as water is excluded and crystals increase in size
40
describe how enamel permeability changes with age
permeability decreases with age, due to increased crystal size and the continued exclusion of water; thus, there is less space between individual crystals
41
describe how changes in emale over time contribute to an overall decreased incidence of caries
* increased fluoride ion content * topographical loss of surface areas susceptible to caries (wear of pits and fissures) * extrinsic factors like dietary changes * less refined carbohydrates consumed by adults
42
describe periodic structural features of enamel
* striae of retzius/perikymata * cross striations
43
describe optical structural features of enamel
* hunter-schreger bands * gnarled enamel
44
describe histological structural features of enamel
* enamel tufts * enamel lamellae * enamel spindles
45
\_\_\_ appear as longitudinal lines or stripes on ground sections (non demineralized) running from the DEJ to the enamel surface
striae of retzius
46
striae of retzius may indicate a weekly rhythm in \_\_\_
enamel deposition (rings on a tree)
47
striae of retzius follow the ___ growth pattern
appositional; move from the inside out, just like enamel
48
striae of retzius may be due to the timing of ___ during tooth development; certain cohorts of cells become active at the same time in a ___ way; the striae may delineate these these cohorts
* ameloblast differentiation * cervical
49
striae of retzius have increased ___ content
organic
50
accentuated striae (darker), such as the neonatal line, indicate what?
significant physiological disturbances
51
what is the neonatal line?
* most accentuated stria of retzius * reflects physiologic changes occurring during birth * found in all primary teeth, sometimes cusps of first permanent molars
52
what is perikymata?
* surface manifestations of striae of retzius visible on the enamel surface * shallow furrows where stria intersect surface
53
cross striations run at a right angle to the ___ direction
rod; more or less the DEJ
54
enamel growth rate is about 4um/day, which is the distance between \_\_\_
cross striations; so they are relatively close together
55
cross striations may indicate what?
cyclical variations in rod (organic, mineral density)
56
ameloblast differentiation (enamel production) proceeds in what direction?
cervically
57
stria of retzius do not run straight; they follow the contour of what?
the cohort of ameloblasts
58
striae of retzius appear best in ___ sections
longitudinal; depending on how you cut into the tooth, striae will appear in different orientations
59
rods run in ___ directions, toward \_\_\_
* all * the tooth surface
60
bands of hunter-schreger are visible in \_\_\_
ground sections
61
\_\_\_ are an optical phenomenon due to differential light ascattering when adjacent groups of rods alternate direction
bands of hunter-schreger they appear as alternating light/dark bands
62
bands of hunter-schreger represent what?
areas of enamel rods cut in cross-section dispersed between areas of rods cut longitudinally
63
bands of hunter-schreger extend 2/3 the distance from the ___ to \_\_\_
DEJ to surface the 1/3 of outer enamel generally runs straighter
64
gnarled enamel is visible in \_\_\_
ground sections
65
gnarled enamel is seen mostly where?
around the DEJ under the cusps/incisal area, short distance into enamel
66
how is gnarled enamel formed?
* from a complex twisting of rods as they proceed vertially away from the DEJ * twisting of vertically directed rods around a small diameter ring * consider that amelogenesis proceeds from the enamel knot/crown towards the cervical region of the tooth
67
what are enamel tufts?
* "tufts of grass" seen in ground sections; look like cracks * project from about 1/3 to 1/2 into the enamel, but do not reach the surface * developmental feature
68
enamel tufts contain more ___ and are \_\_\_
* enamel proteins * hypocalcified
69
enamel tufts are a developmental feature perhaps caused by what?
* abrupt changes in enamel rod direction, possibly due to initial crowding of ameloblasts * crowding causes some gaps where rods meet, which fill with organic material (protein)
70
structurally, ___ convey on enamel a bit of a "give" to help prevent fractures
enamel tufts
71
\_\_\_ appear as cracks in ground sections which traverse the whole length of the enamel
enamel lamellae
72
enamel lamellae contain ___ proteins
organic material
73
describe how enamel lamellae are developmental
areas where enamel proteins not completely removed or trapped bits of the enamel organ
74
what is the function of enamel lamellae?
may function to give the enamel more structural support (like fault lines) to help resist fracture
75
\_\_\_ are the result of odontoblastic processes that traverse the DEJ and penetrate the enamel
enamel spindles
76
enamel spindles proceed a very short distance into \_\_\_
enamel
77
where do enamel spindles often appear?
at incisal and cuspal tips
78
are enamel spindles enamel?
no; they may have trace amounts of dentin (collagen) associated with them
79
what is genetic dysplasia?
developmental problems with tooth development/enamel formation
80
\_\_\_ are very susceptible to physiological changes (birth, high fevers, etc), which can result in disruption in ___ for a time
* ameloblasts * ameloblast function
81
minor physiologic changes cause structural enamel changes visible only \_\_\_
histologically
82
severe physiological changes can do what to enamel?
death or damage of ameloblasts with easily visible defects
83
what is tetracycline staining?
* tetracycline is incorporated into all mineralizing tissues (enamel, detin, cementum, and bone) * brown, yellow, or gray band of pigmentation * tooth form is normal; basically only cosmetic
84
the severity of tetracycline staining is proportional to what?
dose and duration
85
excess fluoride interferes with \_\_\_, resulting in fluorosis or mottled enamel
amelogenesis
86
what are common fluoride induced enamel defects?
* fluorosis or mottled enamel * hypermineralized enamel * chalk white or brown in color * can result in pits on teeth * tooth form is normal
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