Dentin

Question 1

What are 5 distinguishing properties of dentin?

Answer 1

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

Question 2

What colour is dentin?

Answer 2

Pale yellow

Question 3

Rank in order of hardness:

Dentin, Cementum, Enamel

Answer 3

1. Enamel
2. Dentin
3. Cementum

Question 4

What forms dentin?

Answer 4

Odontoblasts

Question 5

Where are the odontoblasts which form dentin found?

Answer 5

Outer border of the dental pulp

Question 6

Describe the gross composition of dentin by volume

Answer 6

50% inorganic
30% organic
20% water

Question 7

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

Answer 7

Collagen (principal fibril is Type I)

Question 8

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

Answer 8

In parallel to the pulp surface

Question 9

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

Answer 9

1. Dentine phosphoproteins

2. Proteoglycans

Question 10

What 3 things can be found in dentinal tubules?

Answer 10

1. Odontoblast processes
2. Afferent nerve axons
3. Dentinal fluid

Question 11

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

Answer 11

The have curvatures

Question 12

What is a contour line of Owen?

Answer 12

Secondary curvatures which coincide in adjacent dentinal tubules

Question 13

Where is a contour line of Owen usually found?

Answer 13

Junction of primary and secondary dentin

Question 14

What is the function of dentinal tubules branching?

Answer 14

Allows intercellular communication

Question 15

Where does the most profuse branching of dentinal tubules occur?

Answer 15

Dentinoenamel junction

Question 16

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

Answer 16

1. Peritubular dentin

2. Intertubular dentin

Question 17

What is peritubular dentin?

Answer 17

Creates the wall of the dentinal tubule

Question 18

What is the intertubular dentin?

Answer 18

Found between dentinal tubules

Question 19

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

Answer 19

1. Peritubular dentin lacks a collagen matrix

2. Peritubular dentin is more mineralised

Question 20

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

Answer 20

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

Question 21

What is Predentin?

Answer 21

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

Question 22

What are the 2 components of primary dentin?

Answer 22

1. Mantle dentin

2. Circumpulpal dentin

Question 23

What is mantle dentin?

Answer 23

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

Question 24

What is circumpulpal dentin?

Answer 24

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

Question 25

When does secondary dentin begin to form?

Answer 25

After root formation is complete

Question 26

Where is secondary dentin usually deposited?

Answer 26

Roof and floor of the chamber reducing pulp cavity

Question 27

How does tertiary dentin arise?

Answer 27

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

Question 28

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

Answer 28

Potential risk of pulp exposure to substances in the oral cavity

Question 29

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

Answer 29

Tertiary dentin deposition occurs and insulates the pulp nerve