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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
Q

What is amelogenesis?

A

Enamel matrix formation

Occurs in response to mantle dentin formation

26
Q

What happens during the first wave of enamel matrix formation?

A

Matrix formed in incisal or occlusal area

Starts closest to the DEJ and moves toward non-masticatory surfaces

27
Q

What happens during the second wave of enamel matrix formation?

A

Growth overlaps the first wave moving cervically toward the CEJ and continues until the crown is completed

28
Q

In what order does mineralization occur?

A

First stage follows the same wave pattern

29
Q

How many ameloblasts form an enamel rod?

A

The head is formed by one ameloblast, the tail is formed by three

30
Q

Which direction do the crystals run in enamel rods?

A

Crystals run parallel to the long axis of the rod

31
Q

What is the rod sheath? Where is it located?

A

Organic/protein covering of the enamel rod

Located between the rod and inter rod substance

32
Q

What direction do crystals run in inter rod substance?

A

Crystals run perpendicular to the rods

Orientation is opposite to the crystals of enamel rods

33
Q

What are daily imbrication lines?

A

Demarcate the daily production of enamel matrix

Similar to “lines of von ebner”

Run perpendicular to enamel rods

34
Q

What are striae of Retzius?

A

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
Q

What are perikymata?

A

Shallow grooves between striae of retzius

36
Q

What are neonatal lines?

A

Metabolic shock of birth recorded in enamel

Accentuated striae of retzius

37
Q

What tissues form the DEJ? What does it replace?

A

Mantle dentin and apristmatic enamel

Replaces the basal lamina/basement membrane

38
Q

How is the DEJ shaped?

A

Scallop shaped

Enamel side is convex
Dentin side is concave

39
Q

Where are enamel spindles found?

A

Only at the DEJ

Extends from dentin through DEJ into enamel

40
Q

What is the clinical significance of enamel spindles?

A

Clinical significance unknown

41
Q

What are enamel spindles?

A

Linear defects of entrapped terminal ends of odontoblastic processes

Does not belong, supposed to be in dentin

42
Q

Where are enamel tufts found?

A

Only at DEJ on enamel side and extend into enamel

43
Q

What is the function of enamel tufts?

A

May help prevent enamel fractures

Creates space for flexture

44
Q

Where are enamel lamellae found?

A

Extend in enamel from outer surface or vice versa from the DEJ

May extend to and through the DEJ into circumpulpal dentin

45
Q

What is the clinical significance of enamel lamellae?

A

Clinical significance unknown

46
Q

What is gnarled enamel formed by?

A

Formed by diverging paths of enamel rods/prisms

47
Q

Where is gnarled enamel found?

A

Found under cusps, preventing cusp fractures by reducing stress

48
Q

What are Hunter Schreger bands?

A

Dark and light bands of reflected oblique light on enamel

Visible only w/ reflective light microscope

49
Q

What are Diazones?

A

Dark bands

50
Q

Wjhat are parazones?

A

Light bands

51
Q

What is the primary enamel cuticle?

A

AKA Nasmyth’s Membrane- protective enamel covering that wears away after eruption

Acellular, non-calcified substance produced by post-ameloblasts

52
Q

What is the secondary enamel cuticle?

A

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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