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Oral E > Chp 8 > Flashcards

Chp 8 Flashcards

(95 cards)

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1
Q

canaliculi

A

Lateral branches of odontoblasts

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2
Q

Dentin classification

A

primary, secondary, and reparative or tertiary dentin.

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3
Q

Is dentin living

A

yes

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4
Q

Dentin is composed of

A

organic matrix of collagen fibers and the mineral hydroxyapatite.

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5
Q

Radiographically, dentin appears more

A

radiolucent than enamel but more radiopaque than pulp.

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6
Q

Dentin Physical Properties

A

Forms bulk of tooth
Composed of 70% inorganic hydroxyapatite crystals, 20% organic fibers, with small amounts of other proteins and 10% water

Resilient

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7
Q

Dentin softer or harder than enamel

A

softer

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8
Q

Dentin softer or harder than bone or cementum

A

Harder than bone or cementum

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9
Q

color of dentin

A

yellow

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10
Q

What allows dentin to incur impact from mastication without fracturing overlying enamel

A

The resilient or elastic nature

This resilience is partly the result of the presence of tubules throughout the matrix.

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11
Q

Primary dentin forms

A

the body of the tooth.
Mantle
Circumpulpal dentin

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12
Q

Secondary dentin forms only

A

after tooth eruption.

Narrow band that borders the pulp

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13
Q

Tertiary or reparative dentin forms

A

only in response to trauma to the pulp.

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14
Q

Mantle dentin is deposited first at the

A

dentinoenamel junction (DEJ).

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15
Q

Normal circumpulpal dentin underlies

A

mantle and globular dentin. It may be 6 to 8 mm thick in the tooth crown and thinner in the tooth roots.

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16
Q

Mantle dentin extends approximately

A

150 µm from the DEJ toward the pulp to the zone of interglobular or globular dentin.

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17
Q

Circumpulpal dentin comprises

A

the bulk of the tooth’s primary dentin. It may be 6 to 8 mm thick in the tooth crown and thinner in the tooth roots.

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18
Q

Mantle dentin is composed of large _____ fibers.

A

collagen

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19
Q

_______ fibers are tenfold smaller than those in mantle dentin.

A

Circumpulpal dentin

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20
Q

______ is slightly less mineralized and contains fewer defects than circumpulpal dentin

A

Mantle dentin

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21
Q

Zones of dentin have structural differences. ______ fibers may be 0.1 to 0.2 µm in diameter, compared with______ matrix fibers of 50 to 200 nm in diameter.

A

Mantle dentin

circumpulpal dentinal

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22
Q

_____ dentin usually exists only in the tooth crown, but can extend into the root.

A

Globular

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23
Q

Globular dentin contains

A

hypomineralized areas between the globules, termed interglobular spaces, which are not true spaces.

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24
Q

Dentinal tubules run through

A

the interglobular spaces, indicating a defect in mineralization, not a defect in matrix formation.

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25
______ is noticeable with vitamin D deficiency, which affects mineralization of teeth and bones.
Interglobular dentin
26
Deposition of secondary dentin may be
uneven as is the case with molar teeth.
27
More secondary dentin is deposited on the roof and floor of the coronal pulp chamber than on the lateral walls. Why?
This is to protect pulpal horns as occlusal function occurs.
28
Secondary Dentin Forms
internally to primary dentin
29
Secondary Dentin Develops after
crown is in clinical occlusal function and roots near completion
30
Secondary Dentin
Deposited slowly, perhaps to prevent pulp obliteration
31
Tertiary Dentin- Results from pulpal stimulation
Attrition Abrasion Caries Restorative procedures
32
Tertiary Dentin Forms only at
site of odontoblastic activation and rapidly
33
A band of newly formed, unmineralized matrix of dentin at the pulpal border
Predentin
34
Predentin is evidence that dentin forms in two stages:
1. Organic matrix is deposited. | 2. Inorganic mineral substance is added.
35
During primary dentin formation, _______ is deposited and calcified each day. After occlusion and function, this activity
4 µm of predentin is deposited | decreases to 1.0 to 1.5 µm per day.
36
What is contained within canaliculi?
Allow for intercellular communication and blood supply
37
What gives the dentin vitality?
odontoblastic process and secondary tubules
38
What is the surface area ratio of the DEJ to the pulpal surface?
5:1
39
How does this surface area ratio affect tubules?
By placing the tubules further a part at the DEJ than the at the pulpal surface
40
What is the significance of secondary tubules?
look in book
41
Interglobular dentin is an area of
deficient mineralization like the area of predentin, which is also not calcified.
42
In some areas, the _____ dentin completely fills the tubules, such as in the area near the DEJ overlying the pulp horns.
hypermineralized intratubular
43
Hypermineralized intratubular dentin also is found in
Hypermineralized intratubular dentin also is found in the peripheral tubules of the root near the cementum. These are areas of very small tubules and areas in which external stimulation might have a role.
44
A hypermineralized collar or dental matrix that immediately surrounds the tubules
Intratubular or Peritubular Dentin
45
Present in tubules throughout dentin, except near the pulp
Intratubular or Peritubular Dentin
46
Missing from dentinal tubules in interglobular dentin
Intratubular or Peritubular Dentin
47
Located between and around the dentinal tubules
Inter tublular dentin
48
_____ dentin is found in areas of attrition, abrasion, fracture, and caries.
Sclerotic dentin
49
_______ eliminated in areas of sclerotic dentin
Pulp permeability
50
This is the term for dentin with tubules that are completely obliterated. Increases in amount with age Believed to be mechanism to protect pulp
Sclerotic Dentin
51
Remember Dentin is deposited in layers Lines indicating a hesitation in deposit of matrix activity are called_____
Lines of Von Ebner
52
This line in dentin reflects the abrupt change in environment that occurs at or near birth.
Neonatal Line
53
Which dentin has fewer defects?
Prenatal dentin.
54
Result of a coalescing and looping of the terminal portions of the dentinal tubules.
Granular Layer of Tomes
55
Is it possible that the odontoblast is initially disoriented as it begins dentin formation?
Yes. Because. It turns at right angles to the root surface and proceeds pulpward, causing the dentinal matrix in this area to be defective. This disorientation of the odontoblasts could be due to the initial incomplete information transmitted by the inner root sheath cells, resulting in the granular layer.
56
Where do odontoblast processes extend to
the DEJ.
57
Cytoplasmic extensions of the odontoblast cell body positioned at
the pulp-dentin border
58
Odontoblast cell processes are largest in diameter near the
near the pulp (3 to 4 µm) and taper to 1 µm near the DEJ.
59
These odontoblast cell processes extend into the enamel for a short distance as enamel ______.
thickens
60
Odontoblast Tubes are father apart at | ____ than _____
DEJ than Pulp.
61
What happens when there is a odontoblastic process death? Why is this significant?
Loss of the odontoblastic process usually results in the appearance of dead tracts in dentin. In the dentin underlying an area of attrition or a carious lesion, odontoblasts may die and processes disintegrate, producing a group of open tubules that contain debris and spaces. If these tubules are open to overlying caries, bacteria can enter them and migrate to the pulp, causing inflammation
62
The only feature that protects the pulp is
that it has higher osmotic pressure Fluid is constantly being forced outward by this increased pressure of the pulp.
63
. When a cavity is prep, the tubules are
cut
64
What layer blocks off the dentin tubules when a cavity is prepared?
Tubules of dentin are blocked by the production of a smear layer on the floor or walls of the cavity preparation.
65
T/F . Bacteria can percolate down the dentinal tubules to the pulp.
true
66
Is dentin laid down throughout life?
Yes
67
Changes in dentin are caused by:
Odontoblastic degeneration Formation of dead tracts Calcification of tubules, leading to sclerosis Tertiary or reparative dentin formation
68
After death and degeneration of odontoblast what happens
dead tracts appear, sclerosis may occur, and further reparative dentin secreted by replacement odontoblast in the pulp forms.
69
Which type of dentin comprises the greater part of the crown and root?
cirumpulpal
70
What factors affect permeability of the dentin?
* particle size * pressure * shape of tubules * size of tubule * calcification of dentin
71
Why are newly restored teeth sensitive for a period of time?
Dentin responds to such stimuli by deposition of reparative dentin and by changes to the dentin tubules underlying the restoration. The sensitivity will diminish after a few weeks because of these changes
72
What is sclerotic dentin?
dentin with tubules that are completely obliterated.
73
____ hard tissue that makes up most of the tooth
dentin
74
t/f dentin is not normally exposed to the oral environment
t
75
root dentin is covered by _____ crown dentin is covered by _____
cementum | enamel
76
dentin is composed primarily of ____ and _____
organic matrix of collagen fibers and mineral hydroxyapatite
77
How is dentin classified
primary, secondary or tertiary
78
_____ dentin is the major component of the crown and root consists of ____ dentin, ____ dentin and ____ dentin
Primary | mantel, globular and circumpulpal
79
____ dentin is deposited first along the DEJ
mantel
80
is mineralized by matrix vesicles | also the collagen fibers of this dentin are larger than circumpulpal dentin which forms later
mantel dentin
81
mantel dentin is separated from circumpulpal dentin by
a zone of disturbed dental formation called globular dentin
82
globular dentin is believed to be a result of
deficient mineralization caused during the final maturation of the odontoblasts
83
How long does dentin continue to form
until the teeth erupt and reach occlusion
84
As the teeth being to function the dentin is termed ________ and is normal _______
secondary dentin | circumpulpal dentin
85
T/F dentin is unresponsive to its environment
false- dentin is responsive to it environment
86
When is dentin deposited
when caires or mechanical trauma affects the pulp
87
This type of dentin is deposited to protect the pulp
reactionary/response or tertiary dentin
88
Bordering the pulp is?
predentin
89
Newly formed dentin before calcification and maturation is called
predentin
90
Predentin is composed of
90% type I collagen fibers and 10% noncollagenous proteins, which calcify within 24 hours as odontoblast deposit a new band
91
odontoblast processes exist in ____ and penetrate _____ from the _____ to the _____
tubules and penetrate dentin from the pulp to the DEJ
92
Dentin like bone is deposited by ______ ______ and produces ______
appositional growth incremental lines
93
Does dentin remodel like bone?
No dentin does not remodel
94
what dentin appears along the root surface
granular dentin
95
How do dead tracts develop in dentin? what is it called?
by odontoblast dying from trauma or old age. tubules calcify. sclerotic/transperant dentin

Oral E (8 decks)

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