Dentin is largely composed of which element?

• Water

• Collagen

• Protein

• Hydroxyapatite

Dentin is more _________ than enamel, and _________than pulp.

• 
  radiolucent; radiolucent

• radiolucent; radiopaque

• radiopaque; radiolucent

• radiopaque; radiopaque

Dentinal tubules are blocked by __________during cavity preparation

• 
  tubule contraction

• sclerotic dentin

• replacement odontoblasts

• a smear layer

Each enamel rod is formed by _____ ameloblast(s).

• one

• two

• three

• four

Enamel tufts are filled with which material?

• Keratin

• Enamelin

• Melanin

• Myosin

Sclerotic dentin is formed by

• the death of odontoblasts

• the outer enamel epithelium

• ameloblasts

• odontoblasts.

Sclerotic dentin is also known as _____________ dentin.

• 
  reactionary

• 
  tertiary

• 
  transparent

• responsive

The scalloped junction between dentin and enamel improves

• 
  flexibility

• permeability

• adherence

• sensitivity

Which best defines tertiary dentin?

• Zone of deficiently mineralized dentin

• Reactionary deposit of dentin, usually as a result of trauma to the pulp

• Calcified tubules resulting from old age or trauma

• The first deposit of dentin along the dentinoenamel junction

Which part of the enamel rod is most susceptible to demineralization?

• Tail

• Head

• Core

• Sheath