Dentin Flashcards

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1
Q

What are 5 distinguishing properties of dentin?

A
  1. Dentin is sensitive
  2. Dentin is permeable
  3. Dentin is formed throughout life
  4. Dentin is softer than enamel
  5. Dentin has greater compressive and flexural strength than enamel
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2
Q

What colour is dentin?

A

Pale yellow

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3
Q

Rank in order of hardness:

Dentin, Cementum, Enamel

A
  1. Enamel
  2. Dentin
  3. Cementum
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4
Q

What forms dentin?

A

Odontoblasts

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5
Q

Where are the odontoblasts which form dentin found?

A

Outer border of the dental pulp

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6
Q

Describe the gross composition of dentin by volume

A

50% inorganic
30% organic
20% water

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7
Q

What is the main component of the organic component of dentin?

A

Collagen (principal fibril is Type I)

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8
Q

How do the collagen fibres run with respect to the pulp?

A

In parallel to the pulp surface

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9
Q

Name 2 other molecules which can be found in the organic component of dentin

A
  1. Dentine phosphoproteins

2. Proteoglycans

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10
Q

What 3 things can be found in dentinal tubules?

A
  1. Odontoblast processes
  2. Afferent nerve axons
  3. Dentinal fluid
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11
Q

What is a major feature, with regards to shape, of dentinal tubules

A

The have curvatures

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12
Q

What is a contour line of Owen?

A

Secondary curvatures which coincide in adjacent dentinal tubules

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13
Q

Where is a contour line of Owen usually found?

A

Junction of primary and secondary dentin

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14
Q

What is the function of dentinal tubules branching?

A

Allows intercellular communication

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15
Q

Where does the most profuse branching of dentinal tubules occur?

A

Dentinoenamel junction

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16
Q

What are 2 ways dentin can be defined due to its relationship with dentinal tubules?

A
  1. Peritubular dentin

2. Intertubular dentin

17
Q

What is peritubular dentin?

A

Creates the wall of the dentinal tubule

18
Q

What is the intertubular dentin?

A

Found between dentinal tubules

19
Q

What are the 2 main differences between peritubular dentin and intertubular dentin?

A
  1. Peritubular dentin lacks a collagen matrix

2. Peritubular dentin is more mineralised

20
Q

What are 2 ways to classify dentin with regards to the time of its development?

A
  1. Predentin
  2. Mineralised
    a) Primary
    b) Secondary
    c) Tertiary
21
Q

What is Predentin?

A

Innermost, unmineralised layer where new dentin is being deposited by odontoblasts

22
Q

What are the 2 components of primary dentin?

A
  1. Mantle dentin

2. Circumpulpal dentin

23
Q

What is mantle dentin?

A

Outermost layer of the crown, with many tubule branches, which prevents any cracks in enamel spreading to dentin

24
Q

What is circumpulpal dentin?

A

Lines the pulp chamber and makes up the majority of dentin within the crown

25
Q

When does secondary dentin begin to form?

A

After root formation is complete

26
Q

Where is secondary dentin usually deposited?

A

Roof and floor of the chamber reducing pulp cavity

27
Q

How does tertiary dentin arise?

A

Reaction to a stimuli e.g. caries, attrition or trauma

28
Q

What is a major clinical consideration of tubular structures of dentin?

A

Potential risk of pulp exposure to substances in the oral cavity

29
Q

How does a tooth reduce in sensitivity following a restorative procedure?

A

Tertiary dentin deposition occurs and insulates the pulp nerve