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Oral Bio II > Dentin > Flashcards

Dentin Flashcards

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1
Q

What is the composition of dentin?

A

70% inorganic, 20% organic, and 10% water

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2
Q

What makes up the organic component of dentin?

A

90% collagen (mostly collagen I with some III and V)

10% non collagenous proteins

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3
Q

What are the dentin specific proteins?

A

DMP-1 and DSPP that gets broken down into three separate proteins by BMP-1

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4
Q

What are the proteins that are made when DSPP is cut up?

What are their functions?

A

DSP-Proteoglycan, may act to prevent mineralization
DGP-Glycoprotein, might have a role in biomineralization
DPP-Initiates HA crystal formation

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5
Q

Defects in DSPP can cause what?

A

Dentinogenesis imperfecta type II and II
Type II- pulp chambers are filled with abnormal dentin
Type III-hypomineralization of dentin, large pulp chambers

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6
Q

Why is it important that some cells don’t fully differentiate into odontoblasts?

A

They can help repair the dentin or replace damaged odontoblasts.

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7
Q

What characteristic of the DEJ helps to resist shearing forces?

A

It is scalloped

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8
Q

The shape of the DEJ is critical for what two reasons?

A

1-defines the shape of the crown
2-keeps dentin directly attached to the enamel
HA crystals from enamel and dentin fuse

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9
Q

What is the first layer of dentin called?

A

Mantle dentin

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10
Q

What protein fibers are associated with mantle dentin?

A

Von Korff’s fibers, they are collagen III fibrils associated with fibronectin

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11
Q

After initial mantle dentin is made, what happens next?

A

odontoblasts start to extend process toward the enamel into the developing dentin matrix, forming Tome’s fibers, these then secrete dentin matrix components in matrix vesicles. Where they penetrate the enamel the make enamel spindles

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12
Q

Why is dentin globular in some places?

A

When it is started by seed crystals (matrix vesicles) it is globular. This happens when dentin is made quickly, tertiary and mantle dentin.

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13
Q

What type of proteins are in the matrix vesicles?

A

They contain the non-collagenous proteins that make the scaffold for dentin formation and resulting in tubular dentin

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14
Q

In the roots, what causes the differentiation of odontoblasts?

A

HERS Hertwig’s epithelial root sheath

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15
Q

What does the HERS become?

A

They eventually break down and form rest cells of Malassez

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16
Q

What is primary dentin?

A

The first dentin formed, comprised of the mantle dentin and the initial deposition of circumpulpal dentin

17
Q

What is secondary dentin?

A

Tubular dentin, laid down subsequent to root formation, and is produced throughout life.

18
Q

T or F: The dentinal tubule closest to the pulp run is a sigmoidal shape?

A

False, tubules that are closer to the DEJ run in a sigmoidal pattern

19
Q

What is tertiary dentin?

A

Dentin that is produced in response to insult.

20
Q

What are the 2 types of tertiary dentin?

A

Reactionary- trauma doesn’t damage odontoblast

Reparative- trauma damages odontoblast, causing of mesenchymal progenitor cells to differentiate into odontoblasts

21
Q

What is different about tertiary dentin?

A

It has less DMP-1 and DSP, so it is usually atubular.

22
Q

What three things make up the macrostructure of dentin?

A

Dentinal tubules, peritubular dentin, and intertubular dentin

23
Q

What signals the odontoblasts that there is damage of the enamel?

A

LPS

24
Q

What are dead tracts?

A

They show up black in a ground section and are caused by air trapped in the tubules after odontoblastic process leaves to damage

25
Q

What is sclerotic dentin?

A

Term for tubules that have become occluded. Can be do to secondary dentin

26
Q

What is interglobular dentin?

A

Areas of hypo-mineralized dentin. More common near mantle dentin

27
Q

How fast is dentin deposited?

A

4µm/day. Every 20µm or 5 days the orientation of collagen changes and forms lines of Von Ebner.

28
Q

What is the rate of mineralization of dentin?

A

2µm/12 hours. It not occurring at the same time as deposition.

29
Q

What are contour lines of Owen?

A

Similar to the neonate line in enamel

30
Q

What is the granular layer of Tomes?

A

They are black dots that occur in root dentin near the DCJ and they get more granular the more apical you go

31
Q

What are the three possible causes of the granular layer of Tomes?

A

1-hypomineralized dentin
2-part of looped dentinal tubules
3-Special structures forming part of the DCJ

Oral Bio II (8 decks)

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