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Oral Bio > Dentin Histology > Flashcards

Dentin Histology Flashcards

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1
Q

Physical properties of dentin

A

color-slightly yellow, enamel appears white

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2
Q

Composition of dentin

A

HAP (inorganic) -70%
Type 1 Collagen fibers (organic)-20%
Water-10%

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3
Q

What gives tooth its color

A

dentin

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4
Q

How much of the pulp does dentin cover

A

All of it

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5
Q

Function of dentin as it pertains to enamel

A

shock absorber for enamel (less mineralized and less brittle)

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6
Q

T/F, dentin is calcified?

A

T

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7
Q

The organic matrix of dentin is primarily composed of what

A

collagen type 1 (~90%)

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8
Q

In order of most to least mineralized tissue

A

Enamel > Dentin > Cementum > Bone

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9
Q

______ induce odontoblast polarization @ inner enamel epithelium (dentin of crown)

A

ameloblast

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10
Q

Where dentin formation begins and in which direction

A

DEJ and moves towards pulp

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11
Q

Odontoblasts form dentin in two stages:

(2)

A

substance is added (1) organic matrix is deposited

(2) an inorganic mineral

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12
Q

Responsible for root development

A

Hertwig’s epithelial root sheath

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13
Q

Primary dentin (when is it developed? What is it composed of?)

A

developed prior to eruption

composed of mantle and circumpulpal dentin

Interglobular dentin
Peritubular and intertubular dentin

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14
Q

Secondary dentin (when is it developed/what is it composed of?)

A

After eruption

circumpulpal dentin

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15
Q

tertiary dentin (when is it developed/what is it composed of?)

A

after eruption, caused by stimuli

Reactionary/response dentin

Reparative dentin

Osteodentin

Sclerotic dentin

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16
Q

Mantle dentin (when does it arise)

A

during initial phase of dentinogenesis-it is the first dentin formed

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17
Q

Mantle dentin is a product of what type of odontoblasts

A

immature-not fully differentiated

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18
Q

mantle dentin extends how far (range) pulpwards

A

10 to 30 µm up to 150 µm

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19
Q

Mantle dentin is composed of what type of collagen fibers

A

large collagen fibers

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20
Q

Mantle dentin mineralization

A

less mineralized than later formed circumpulpal

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21
Q

what happens after odontoblast form mantle layer?

A

with formation of this first layer of dentin, odontoblasts begin to draw away from inner enamel epithelium

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22
Q

Where does mantle dentin interact with enamel

A

DEJ,

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23
Q

Primary dentin-circumpulpal dentin (rate of formation and mineralization)

A

fast formation-4um/day

highly mineralized

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24
Q

Secondary dentin circumpulpal dentin (rate of formation and mineralization)

A

Slower formation-1um a day

less mineralized than primary dentin

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25
Q

Thickness of circumpulpal dentin

A

6-8 mm thick

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26
Q

With age what happens to the pulp

A

shrinks as dentin grows

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27
Q

collagen fibers of circumpulpal dentin

A

collagen fibers (50 - 200 nm) are 10 times smaller than in mantle dentin, parallel to DEJ

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28
Q

non mineralized dentin

A

predentin

29
Q

types of mineralized dentin (2)

A

peritubular and intertubular dentin

30
Q

intertubular dentin (function)

A

connects the dentinal tubules

31
Q

Odontoblasts are part of the pulp tissue. Dentin and pulp are _________

A

“functional units”.

32
Q

Shape of dentinal tubules?

A

S-Curved

33
Q

dentin moves in which direction as it forms

A

pulpwards

34
Q

how dentin tubules form

A

as a result of dentin lengthening as the odontoblast move

35
Q

Where do dentinal tubules start

A

@ DEJ but may extend into forming enamel matrix=enamel spindles

36
Q

Tomes’ Fibers

A

occupied by odontoblastic processes

37
Q

How many processes do odontoblast initially have

A

multiple

38
Q

after final differentiation secondary processes are within _______ ??

A

canaliculi

39
Q

are dentinal tubules living tissue? is there communication?

A

yes

40
Q

From the pulp to the DEJ, dentinal tubules _______

A

density and diameter of tubules decreases

41
Q

intratubular dentin

A

Dentin that is located between or around the dentinal tubules

42
Q

Known as the body of the dentin

A

intratubular dentin

43
Q

composition of intratubular dentin (compare to peritubular)

A

same mineral and organic components like peritubular dentin, but less calcified

44
Q

Changes to the intratubular dentin overtime

A

little change through life

45
Q

Process of dentin getting mineralized?

A

Predentin-mineralized-predentin-mineralixed etc

first, organic matrix is deposited, and second, inorganic mineral substance is added

46
Q

Predentin

A

newly formed, unmineralized matrix at pulpal border

47
Q

Predentin mineralization occurs at the ________

A

PD-D junction (pre-dentin-dentin junction)

48
Q

After occlusion and function secondary dentin is formed and only______ dentin is deposited and calcified each day

A

1.0 to 1.5 µm/d

49
Q

Formation of circumpulpal dentin continuous?

A

NO

50
Q

„resting phases“ appear how in dentin

A

in demineralized sections of dentin as lines

51
Q

distance between incremental lines

A

20um

52
Q

width of incremental lines

A

width varies from 8 µm coronally to 3 µm apically

53
Q

direction of incremental lines

A

right angle to tubules

54
Q

Official name for incremental lines

A

„incremental lines of von Ebner“

or hypocalcified bands

55
Q

incremental lines are

equivalent to incremental lines of

A

Retzius in enamel

56
Q

How contour lines of owen form

A

metabolic disturbances during dentinogenesis affects the formation of matrix and mineralization of dentin

caused by birth (=neonatal line) or by systemic diseases during childhood years

width depends of the duration of cause

57
Q

where do contour lines of owen occur

A

occur at irregular intervals and in variable numbers

58
Q

Contour lines of owen first described by who

A

first described from Sir Richard Owen (1804-1892), Anatomist in London

59
Q

Vitality can be defined as ability to react to physiologic and pathologic stimuli.
(2)

A
  1. Pain perception

2. Functional adaption

60
Q

Functional adaption: of vitality includes

A

secondary dentin, tertiary dentin, dentin sclerosis ???

61
Q

Tertiary dentin and dentin sclerosis also part of

A

defense mechanisms

62
Q

dentin sclerosis

A

Thickening of peritubular dentin and (up to) complete obliteration of dentin tubules

deposition of apatite crystals and collagen in dentinal tubules caused be irritating stimuli (e.g. caries, attrition, erosion, cavity preparation) blocking of tubules = defensive reaction also aging process sclerotic dentin appear light in ground sections vs. dark areas = dead tracts

Wtf does that mean

63
Q

How can you kill odontoblast during a prep

A

overheating with not enough water irrigation

64
Q

Dead tracts

what, how are they caused

A

represents empty, air filled tubules due to degeneration of odontoblastic process (caries, erosion, attrition)

dentin trauma cause the odontoblastic processes within the dentinal tubules to „die back“ toward cell body in severe cases even odontoblasts may die

65
Q

Tertiary dentin (from what, where?)

A

results from pulp stimulation only in localized areas along dentin-pulp interface

66
Q

what does the presence of tertiary dentin mean

A

correspond to those zones of dentin where tubules have been exposed peripherally through attrition, erosion, caries, or therapeutic interventions

clearly demarcated boundary

reactionary/response = deposition by odontoblasts

reparative = newly recruited odontoblasts (from undifferentiated cells of the pulp)

67
Q

dentin adhesive and restorations

A

adhesives stay on enamel b/c it is mostly mineral and can etch- dentin is 10% water and 20% organic matrix so it is hard to adhere

68
Q

Prep dentin, what do you have after prep?

A

a smear layer

69
Q

What to do with smear layer of dentin after prep

A

etch it to remove it

Oral Bio (9 decks)

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