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Histopathology > Exam 1 - Amelogenesis & Enamel > Flashcards

Exam 1 - Amelogenesis & Enamel Flashcards

1
Q

The formation of enamel involves secretory and resorptive activities of _____ derived cells.

A

ectodermally

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2
Q

Where is the enamel crystal located?

A

located in the core of the enamel rod

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3
Q

Are hydroxyapatite crystals large or small?

A

extremely large

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4
Q

Where does acid or acid-etch preferentially attack?

A

ends of the enamel crystals

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5
Q

T/F: Enamel rod structure exhibits flexibility.

A

TRUE

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6
Q

What are the percentage compositions of enamel?

A

1% water
3% organic components (TRAP proteins)
96% inorganic (HA crystals)

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7
Q

What are the 4 tyrosine-rich amelogenin (TRAP) proteins?

A

amelogenin
enamelin
tuftelin
sheathlin

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8
Q

Which organic component of enamel constitutes the bulk of the protein in enamel?

A

amelogenin

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9
Q

_____ functions in the growth of the enamel rods.

A

Enamelin

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10
Q

_____ is a linking protein found in enamel tufts along the DEJ.

A

Tuftelin

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11
Q

Where would you find tuftelin in enamel?

A

right along the DEJ

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12
Q

____ is an enamel protein found in rod sheaths.

A

Sheathlin

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13
Q

Amelogenin exhibits _____ properties, which means it is very viscous and tends to flow very slowly under pressure.

A

thixotropic

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14
Q

What property of amelogenin assists with orientation?

A

its thixotropic, flowing properties of its matrix

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15
Q

As enamel crystal size ____, amelogenin flows away from crystals and back towards the ameloblasts where it is degraded by proteolytic enzymes.

A

increases

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16
Q

What happens to amelogenin as enamel crystal size increases?

A

amelogenin flows away from the crystals

flows back towards ameloblasts to be degraded

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17
Q

Which proteolytic enzymes degrade amelogenin?

A

enamelysin
MMP-20
serine proteases

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18
Q

Is enamel matrix labile or stable?

A

labile (quantitative and qualitative changes)

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19
Q

____ is an acidic, phosphorylated and glycosylated protein.

A

Enamelin

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20
Q

Which organic enamel protein is the largest?

A

enamelin

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21
Q

Enamelin is ONLY found in the ____ area.

A

enamel rod

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22
Q

Enamelin is found near the growing ends of crystals and this suggests that it is involved in ____.

A

growth

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23
Q

____ is found only at the DEJ and is thought to play a role in linking and junction of enamel and dentin.

A

Tuftelin

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24
Q

The inner enamel epithelium stimulates odontoblast differentiation within the _____.

A

dental papilla

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25
The _______ specifies the "dental nature" of the underlying mesenchyme (neural crest cells).
pre-tooth bud stage ectoderm
26
What induces the formation and proliferation of the dental lamina?
neural crest cells (ectomesenchyme)
27
What does the dental lamina eventually separate into?
inner and outer enamel epithelium
28
____ secrete the mantle layer of dentin.
Odontoblasts
29
Once the _____ is formed, ameloblast differentiation is initiated and amelogenesis begins.
mantle layer of dentin
30
What is the pattern of cellular differentiation, matrix secretion, and mineralization during tooth development?
anterior >> posterior | crown >> down (apex)
31
What are the stages of ameloblast function?
1) Morphogenic Stage 2) Differentiation Stage 3) Secretory Stage 4) Maturation Stage 5) Protective Stage
32
At what stage do ameloblasts start to go from low cuboidal to low columnar?
morphogenic stage
33
During which stage of ameloblast formation does the nucleus polarize to one side of the columnar cell, contain lots of mitochondria and form junctional complexes at the basement membrane?
differentiation stage
34
During which stage of ameloblast formation are odontoblasts induced by ameloblast formation at the basement membrane?
differentiation stage
35
Which stage induces odontoblasts to make mantle dentin?
differentiation stage
36
During which stage of ameloblast formation are tome's processes formed?
secretory stage
37
Do tome's processes contain alkaline phosphatase?
YES - secrete from their granules
38
What make up the forming face of enamel formation?
tome's processes
39
During which stage of ameloblast formation does the cell decrease in height and oscillates between a ruffled and smooth border?
maturation stage
40
What is the purpose of the ruffled border?
increases surface area for adding minerals to harden enamel
41
During which stage of ameloblast formation does the basal lamina attach to the ameloblasts to enamel and reduce the enamel epithelium?
protective stage
42
During which stage of ameloblast formation does Nasmyth's membrane form?
protective stage (cuticle layer)
43
How many ameloblasts contribute to the composition of one enamel rod?
4
44
What is the pattern of hydroxyapatite in the formation of enamel rods?
key hole pattern
45
How wide is a typical enamel rod?
60 nm wide
46
T/F: Enamel rods typically run superiorly to inferiorly.
FALSE; they run left to right
47
What determines the angle enamel rods are formed at?
tome's processes
48
How often do tome's processes constrict?
every 4-8 days
49
The constriction of tome's processes form ____, angled striations.
Striae of Retzius
50
Striae of Retzius run ____ to the enamel rods.
angled/perpendicular
51
Striae of Retzius are incremental lines produced by period constriction of _____.
tome's processes
52
What is associated with corresponding increased in the face forming interrod enamel?
Striae of Retzius
53
What represents about 4-8 days of rhythmic enamel matrix apposition?
Striae of Retzius
54
What are the cross striations on each rod?
they represent 24 hours of enamel matrix production (AKA incremental growth)
55
The _____ is an exaggerated hypomineralized Striae of Retzius that forms at birth.
neonatal line
56
What are the external surface manifestations of Striae of Retzius called?
perikymata (imbrication lines of Pickerell)
57
Is the neonatal line hyper- or hypomineralized?
hypomineralized
58
_____ are an optical phenomenon produced by changes in the direction of enamel rods (seen only with reflected light).
Hunter-Schreger bands
59
Where do we most commonly find gnarled enamel?
in the cusp tips
60
Why is gnarled enamel beneficial in cusp tips?
because it is very resistant to fracture and abrasion
61
T/F: Gain of organization of enamel is important for occlusion at cusp tips.
FALSE; loss of organization allows strong gnarled enamel to form at the cusp tips and resist abrasion
62
Are enamel lamellae hypomineralized or hypermineralized areas of enamel that extend from the DEJ up into the enamel?
hypomineralized
63
What hypomineralized area of enamel may be involved in smooth surface caries?
enamel lamellae
64
_____ extend from the DEJ up into the enamel; _____ extend from the enamel surface down to the DEJ and dentin.
Enamel lamellae; enamel cracks
65
Enamel cracks (do/don't) distinguish the DEJ.
DON'T (will keep cracking through dentin)
66
_____ are hypomineralized areas of enamel at the DEJ that are rich in enamelin and tuftelin.
Enamel tufts
67
What structure at the DEJ can prevent shearing forces and breakage?
enamel tufts
68
What are the trapped extensions of odontoblastic processes and tubules across the basal lamina during the initial stages of matrix formation called?
enamel spindles
69
___ are processes of odontoblasts that have become trapped within the enamel matrix and then mineralized in place.
Enamel spindles
70
_____ is delay in the removal of amelogenin during maturation of the enamel matrix.
Hypomineralization
71
What happens if not enough amelogenin is resorbed by proteases?
HIGH protein content LOW hydroxyapatite content LOW mineralization = enamel chips off easily
72
_____ is characterized by chalky white, opaque discoloration.
Hypomineralization
73
_____ results in notched central incisors and "mulberry molars."
Hypoplasia
74
What is hypoplasia usually induced by?
infectious childhood diseases which leave defects in teeth as they were actively mineralizing - measles, rheumatic fever, mumps, syphilis
75
Your young patient presents with Hutchinson's teeth and mulberry molars. What do you suspect happened during development?
neonatal syphilis infection OR some childhood disease that affected development
76
Mottled enamel = _____; may manifest as brown spots, opaque areas and surface pitting.
fluorosis
77
Amelogenesis imperfecta is an _____ genetic disease.
autosomal dominant
78
What condition results from defective enamel matrix deposition that voids the possibility of any enamel mineralization?
amelogenesis imperfecta
79
Can veneers or composite work for patients with amelogenesis imperfecta?
NO because composite and veneers require bonding to NORMAL tooth structure
80
At what point in the stages of tooth development do enamel pearls and cervical enamel projections (CEP) occur?
apposition and maturation stages
81
Why do enamel pearls and cervical enamel projections (CEP) occur?
displacement of ameloblasts to the root surface
82
Enamel pearls usually involve _____; CEPs usually involve _____.
maxillary molars; mandibular molars
83
Why are CEP detrimental to the root surface?
because the PDL cannot attach to enamel, so these patients are left with slippery, deep pockets
84
___ is the deep invagination of the crown or root that is lined with enamel.
Dens-in-dente
85
Where are dens-in-dente most commonly found in patients?
maxillary incisors
86
What is the primary problem of dens-in-dente?
they are followed by gross decay due to trapping of particles deep in the tooth structure
87
How thick is enamel over the cusps?
2-2.5 mm
88
The ____ is comprised of glycoprotein precipitates derived from saliva and gingival crevicular fluid.
enamel pellicle
89
When the tooth erupts, the enamel cuticle forms and the rest of the epithelium becomes the ____.
junctional epithelium

Histopathology (7 decks)

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