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121 Histology & Embryology > Enamel > Flashcards

Enamel Flashcards

1
Q

Where is enamel located?

A

Covers the entire anatomical crown

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2
Q

What kind of fluoride is beneficial at all ages?

A

Topical fluoride (post-eruptive)

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3
Q

What type of fluoride in beneficial only during amelogenesis?

A

Systemic fluoride (pre-eruptive)- ingested during odontogenesis

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4
Q

Characteristics of formed enamel

A

No viable cells, no blood supply, no reparative capabilities

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5
Q

What factors cause demineralization of formed enamel?

A

External factors: bacterial acids lower oral pH to < 5.5

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6
Q

What is the color of enamel? What determines it?

A

Ranges from yellow to blue-white

Depends on translucency

Incisal edges are whiter/more translucent
Bulk of crown yellow/white
Darkens with age
Primary teeth are whiter

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7
Q

What is attrition?

A

Slight to excessive natural wearing process of functional occlusal contact

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8
Q

What is bruxism?

A

Excessive/traumatic grinding and/or clenching causing severe occlusal wear

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9
Q

What is abrasion?

A

Mechanical wearing of tooth surface by forces other than mastication

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10
Q

What is erosion?

A

Loss of tooth structure by a chemical process other than bacterial

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11
Q

What is abfraction?

A

Loss of tooth tooth structure by biochemical loading forces, flexure and chemical fatigue degradation of enamel (cervical area) distant from loading point

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12
Q

What are the inorganic components of enamel?

A

96% mineral- calcium hydroxyapatite, carbonate, magnesium, potassium, sodium and fluoride ions

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13
Q

What are the main organic components of enamel?

A

2% enamel matrix (enamel protein fibers)

  • Enamelin
  • Amelogenin
  • Ameloblastin
  • Tuftelin

1-2% water

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14
Q

What is the function of enamelin? Where is it found?

A

Matrix formation and crystal growth

Present throughout formed enamel

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15
Q

What is the function of amelogenin? What happens to it?

A

Matrix formation
Separates and supports crystal growth

Completely resorbed by ameloblasts during mineralization

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16
Q

What is the function of ameloblastin?

A

Crystal elongation and mineralization

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17
Q

What happens to amelogenin and ameloblastin?

A

Get resorbed by ameloblasts to allow the hardening of enamel

Backfills it with minerals after resorption

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18
Q

What is the function of tuftelin? Where is it located?

A

Mineralization and structural organization

Increased amount at DEJ and on surface of growing crystals

Some gets left behind after resorption

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19
Q

What is the embryonic origin of enamel?

A

Ectoderm
Ectodermal lining in stomodeum gives rise to primary dental lamina= enamel buds and organs

EPITHELIAL

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20
Q

What happens during the bud stage?

A

Enamel organ (dental lamina) formed

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21
Q

What happens during the cap stage?

A

Inner enamel epithelium forms

22
Q

What happens during the bell stage?

A

Pre-ameloblasts formed

23
Q

What happens during apposition?

A

Ameloblasts form

24
Q

What happens during termination?

A

Post-ameloblasts form (reduced enamel epithelium)

25
What is amelogenesis?
Enamel matrix formation Occurs in response to mantle dentin formation
26
What happens during the first wave of enamel matrix formation?
Matrix formed in incisal or occlusal area Starts closest to the DEJ and moves toward non-masticatory surfaces
27
What happens during the second wave of enamel matrix formation?
Growth overlaps the first wave moving cervically toward the CEJ and continues until the crown is completed
28
In what order does mineralization occur?
First stage follows the same wave pattern
29
How many ameloblasts form an enamel rod?
The head is formed by one ameloblast, the tail is formed by three
30
Which direction do the crystals run in enamel rods?
Crystals run parallel to the long axis of the rod
31
What is the rod sheath? Where is it located?
Organic/protein covering of the enamel rod Located between the rod and inter rod substance
32
What direction do crystals run in inter rod substance?
Crystals run perpendicular to the rods Orientation is opposite to the crystals of enamel rods
33
What are daily imbrication lines?
Demarcate the daily production of enamel matrix Similar to "lines of von ebner" Run perpendicular to enamel rods
34
What are striae of Retzius?
Represent the successive apposition of different layers of enamel during crown formation Arches/rings that run perpendicular to rod/prism Intermittent, overlapping areas seen on the labial surface
35
What are perikymata?
Shallow grooves between striae of retzius
36
What are neonatal lines?
Metabolic shock of birth recorded in enamel Accentuated striae of retzius
37
What tissues form the DEJ? What does it replace?
Mantle dentin and apristmatic enamel Replaces the basal lamina/basement membrane
38
How is the DEJ shaped?
Scallop shaped Enamel side is convex Dentin side is concave
39
Where are enamel spindles found?
Only at the DEJ Extends from dentin through DEJ into enamel
40
What is the clinical significance of enamel spindles?
Clinical significance unknown
41
What are enamel spindles?
Linear defects of entrapped terminal ends of odontoblastic processes Does not belong, supposed to be in dentin
42
Where are enamel tufts found?
Only at DEJ on enamel side and extend into enamel
43
What is the function of enamel tufts?
May help prevent enamel fractures Creates space for flexture
44
Where are enamel lamellae found?
Extend in enamel from outer surface or vice versa from the DEJ May extend to and through the DEJ into circumpulpal dentin
45
What is the clinical significance of enamel lamellae?
Clinical significance unknown
46
What is gnarled enamel formed by?
Formed by diverging paths of enamel rods/prisms
47
Where is gnarled enamel found?
Found under cusps, preventing cusp fractures by reducing stress
48
What are Hunter Schreger bands?
Dark and light bands of reflected oblique light on enamel Visible only w/ reflective light microscope
49
What are Diazones?
Dark bands
50
Wjhat are parazones?
Light bands
51
What is the primary enamel cuticle?
AKA Nasmyth's Membrane- protective enamel covering that wears away after eruption Acellular, non-calcified substance produced by post-ameloblasts
52
What is the secondary enamel cuticle?
AKA Acquired pellicle Acellular, amorphous, organic, tenacious, insoluble protein membrane Made from salivary glycoproteins and sulcular glycoproteins Covers the teeth and entire mouth

121 Histology & Embryology (15 decks)

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