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Oral Biology - Quiz 2 > Enamel II > Flashcards

Enamel II Flashcards

(41 cards)

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1
Q

Rods and interrod enamel geometry are linked to the geometry of what?

A

Individual ameloblasts

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2
Q

Rods are __________ from the inner enamel to the outer.

A

Continuous

Innermost and outermost - NO RODS

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3
Q

The ______ end of tomes process directly forms ____ enamel rod (and surrounding interrod enamel.

A

Distal

1

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4
Q

Interrod enamel formed first, makes a what into which the enamel rod is synthesized?

A

Pit

*1 ameloblast = 1 rod, w/ correspondence from inner to outer enamel

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5
Q

Most tooth structure is _______, and how does it form?

A

Dentin

Forms inwards toward the pulp

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6
Q

Enamel is formed ________, but as a cap. The dentin forms _______, making up most of the tooth body.

A

Outwards

Inwards

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7
Q

T/F - Enamel formation is NOT simultaneous. It goes APICALLY.

A

TRUE

*Thus as the crown grows, there are new ameloblasts coming into play cervically

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8
Q

What are the 3 enamel proteins in the enamel deposition?

A

Amelogenins

Ameloblastin

Enamelin

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9
Q

What 2 enamel proteins is key in organic component degradation?

A

Enamelysin**

Enamel matrix serine protease

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10
Q

What enamel proteins are used in basal lamina during maturation?

A

Form the thing that the cells stick to

  • Amelotin
  • Odontogenic ameloblast associated protein
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11
Q

Tell me about amelogenins.

A

MAIN PROTEIN FAMILY IN DEVELOPING ENAMEL (80-90%)

  • Only expressed while enamel is being produced (stops during maturation).
  • Restricts lateral HA crystal growth, preventing crystal fusion

LOSS OF FUNCTION = NO ENAMEL RODS

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12
Q

Tell me about ameloblastin.

A

Around 10% of the enamel organic content

Expressed all the way thru to maturation

Ameloblast adhesion to developing enamel

LOSS OF FUNCTION = AMELOBLASTS FALL OFF, NO ENAMEL

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13
Q

Tell me about enamelin.

A

Least abundant enamel protein 5%

Only present at the leading edge of enamel deposition

LOSS OF FUNCTION = NO ENAMEL

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14
Q

What is enamelysin?

A

MMP - This is MMP 20

Found during enamel deposition

Chops up ameloblastin and enamelin

LOSS OF FUNCTION = THIN, IMMATURE ENAMEL

This is critical for removal of orgo component to allow increased mineralization

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15
Q

Tell me about enamel matrix serine protease.

A

Secreted during moldulation event of enamel maturation

Degrades amelogenins

Loss of function = Immature enamel

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16
Q

Basal lamina doesn’t seem to contain much if any _______.

A

Collagen IV

It has other proteins

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17
Q

Why etch?

Study These Flashcards
A

Fissure sealants

Bonding restorative materials to enamel

Cementing orthodontic materials to enamel

18
Q

What does etching do?

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A

Provides better bonding surface, as etching increases the porosity of the surface

Also removes any crap clinging to enamel surface

This is done be dissolving enamel crystals

19
Q

More carbonated apatite is found where?

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A

In the crystal core

More vulnerable - more prevalent in inner enamel

20
Q

In etching, tell me about dissolving.

Study These Flashcards
A

Inside out

Due to the carbonated apatite in crystal core

The ends first to dissolve, then along the core

21
Q

What does fluoride do?

Study These Flashcards
A

Stabilizes the HA lattice by replacing the OH group

Strengthens it

Also, FA (fluroapatite) forms more quickly than HA

22
Q

Three patterns of etching.

Study These Flashcards
A

I - Most common
—Removal of rods

II - Reverse of Type I, interrod enamel removed

III - Least frequent
—Irregular and indiscriminate pattern

23
Q

What is attrition?

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A

Wear

Enamel cannot be replaced

May expose dentin (bad)

Topographical features pits and fissures may be eliminated

24
Q

Abrasion?

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A

Removal of enamel by force

25
A fraction?
Notch-like cervical lesions -Caused by cyclic loading of teeth which places stress on the interrod-rod interface, causing rods to separate
26
Erosion?
Removal of enamel by break down of crystals (via acids)
27
What are some changes in enamel due to age?
COLOR - Darkness increases with age - Thinning of enamel - Extrinsic staining NATURE OF SURFACE LAYER - Changes due to ionic exchange from oral environment - Fluoride ion most prevalent WATER CONTENT DECREASES -Crystals enlarge and decrease pore size BRITTLENESS INCREASES -Water is excluded and crystals increase in size PERMEABILITY DECREASES Increased crystal size and the continued exclusion of water (Less space b/t individual crystals)
28
T/F - Changes in enamel over time contribute to an overall decreased incidence of caries.
TRUE Higher F- content more mature enamel
29
What are three structural feature of enamel?
Periodic -Connected to temporal events Optical -Light reflection of structural features Histological -Results of cells doing different things
30
PERIODIC FEATURE 1 Tell me what Striae of Retzius is.
Appear as longitudinal lines or stripes on ground sections (Thin strip of tooth, not demineralized) running from DEJ to enamel surface May indicate a weekly rhythm in enamel deposition May delineate different cohorts of cells as they become active at the same time in a cervical way INCREASED ORGO CONTENT NEONATAL LINE -Darker line that is most accented
31
What is the most accentuated stria of Retzius?
Neonatal line Reflects physiologic changes occurring during birth Found in all primary teeth, sometimes cusps of first permanent molars
32
What is perikymata?
Surface manifestions of Striae of Retzius Shallow furrows where stria intersect surface
33
PERIODIC FEATURE 2 Cross striations. Tell me about them.
Visible bands or lines in ground sections Run at a right angel to the rod direction (More or less the DEJ) Close together, 4 micrometers/day May indicate cyclical variations in rods
34
OPTICAL FEATURE 1 Bands of Hunter-Schreger. Tell me about them
Visible bands in ground sections Optical phenomenon due to differential light scattering when adj groups of rods alternate direction Appear as alternating light/dark bands Represent areas of enamel rods cut in cross-section dispersed b/t areas of rods cut longitudinally
35
OPTICAL FEATURE 2 Gnarled Enamel. Tell me.
Visible in ground sections Mostly seen around DEJ under the cusps/Invisalign area short distance into enamel Complex twisting of rods as they proceed vertically away from the DEJ
36
HISTOLOGICAL FEATURE 1 Enamel Tufts. Tell me.
Tufts of grass seen in ground sections - Look like cracks Project form 1/3 to 1/2 into enamel. DO NOT REACH THE SURFACE Contain more enamel proteins and are hypocalcified Structurally, convey on enamel a bit of a give, helping to prevent fractures
37
HISTOLOGICAL FEATURE 2 Enamel lamellae. Tell me
Appear as cracks in ground sections which traverse the whole length of the enamel Contain orgo material proteins Developmental - Areas where enamel proteins not completely removed or trapped bits of the enamel organ May function to give enamel more structural support to resist fracture
38
HISTOLOGICAL FEATURE 3 Enamel spindles. Tell me.
Result from odontoblastic processes that transverse the DEJ and penetrate the enamel Proceed only a very short distance into enamel Often appear at Invisalign and cuspal tips NOT ENAMEL, ITS DENTIN
39
What is genetic dysplasia?
Developmental problems with tooth development/enamel formation Ameloblasts very susceptible to physiological changes (birth, high fever) which result in disruption in ameloblast function for a time
40
What does tetracycline do?
It’s incorporated into all mineralizing tissues (enamel, dentin, cementum, bone) Brown, yellow, or gray band of pigmentation Severity proportional to dose and duration Tooth form is normal - Basically only cosmetic
41
Too much fluoride?
Excess fluoride interferes with amelogenesis Results in fluorosis or motile enamel results Hypermineralized enamel Chalk white/brown in color Can result in pits on teeth Tooth form normal

Oral Biology - Quiz 2 (3 decks)

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