Amelogenesis (2ed)

What is the primary function of ameloblasts?

• A. Dentin mineralization

• B. Enamel formation

• C. Cementum deposition

• D. Crown elongation

Answer: B. Enamel formation

What occurs first in amelogenesis?

• A. Tomes’ process formation

• B. Deposition of enamel matrix at the DEJ

• C. IEE cells turn into ameloblasts

• D. Formation of rod enamel

Answer: C. IEE cells turn into ameloblasts

What stage of amelogenesis is associated with 96% mineral content in enamel?

• A. Presecretory stage

• B. Secretory stage

• C. Maturation stage

• D. Protective stage

Answer: C. Maturation stage

What differentiates rod and interrod enamel?

• A. Mineral composition

• B. Orientation of crystallites

• C. Organic content

• D. Thickness

Answer: B. Orientation of crystallites

What happens to ameloblasts after tooth eruption?

• A. They continue secreting enamel matrix

• B. They degenerate

• C. They are lost

• D. They form the dental papilla

Answer: C. They degenerate

What is the first matrix secreted by ameloblasts?

• A. Enamel rods

• B. Structureless enamel

• C. Rod sheath

• D. Interrod enamel

Answer: B. Structureless enamel

Which structure defines the boundary between enamel and dentin?

• A. Ameloblast junction

• B. Dentino-enamel junction (DEJ)

• C. Rod sheath

• D. Reduced enamel epithelium

Answer: B. Dentino-enamel junction (DEJ)

What process removes organic material from enamel during maturation?

• A. Programmed cell death of ameloblasts

• B. Ruffle-ended ameloblast activity

• C. Secretion of Tomes’ processes

• D. Basement membrane fragmentation

Answer: B. Ruffle-ended ameloblast activity

What connects ameloblasts during enamel formation?

• A. Rod sheaths

• B. Junctional complexes

• C. Interrod enamel

• D. Stratum intermedium

Answer: B. Junctional complexes

What role does the reduced enamel epithelium (REE) play?

• A. Forms enamel rods

• B. Protects enamel during eruption

• C. Stimulates odontoblast activity

• D. Mineralizes the DEJ

Answer: B. Protects enamel during eruption

Enamel can regenerate after tooth eruption.

Answer: False

Explanation: Ameloblasts are lost after tooth eruption, so enamel cannot regenerate.

The first enamel formed is structureless.

Answer: True

Explanation: The initial enamel deposited by ameloblasts at the DEJ lacks rod and interrod structure.

Tomes’ processes are responsible for forming rod and interrod enamel.

Answer: False

Explanation: Dictating the orientation and structure of the developing enamel rods

The maturation stage involves the removal of water and organic material from enamel.

Answer: True

Explanation: During maturation, ameloblasts remove organic material and water, increasing enamel mineral content.

Enamel matrix is secreted after ameloblast polarization.

Answer: True

Explanation: Polarization of IEE cells marks the differentiation into ameloblasts, leading to matrix secretion.

Enamel and dentin formation begin at different locations.

Answer: False

Explanation: Both enamel and dentin formation begin at the dentino-enamel junction (DEJ).

Amelogenesis is primarily under genetic control.

• Answer: True

• Explanation: The process is tightly regulated by genetic and cellular signals, ensuring proper enamel formation.

Ruffle-ended ameloblasts help transport calcium ions into enamel.

Answer: True

Explanation: Ruffle-ended ameloblasts regulate calcium transport, critical for enamel mineralization.

The rod sheath is a space filled with organic material between rod and interrod enamel.

Answer: True
Explanation: The rod sheath contains organic material separating rod and interrod enamel.

The reduced enamel epithelium (REE) is formed during the secretory stage.
Answer: False

1. Explanation: REE is formed during the protective stage, after enamel maturation.

What is the role of Tomes’ processes in amelogenesis?

dictating the orientation and structure of the developing enamel rods

Why can’t enamel regenerate after tooth eruption?

• Answer: Enamel cannot regenerate because ameloblasts are lost after eruption.

What is the significance of the dentino-enamel junction (DEJ)?

Answer: The DEJ is the boundary where enamel and dentin formation begins and provides structural integrity.

How do ruffle-ended ameloblasts contribute to enamel maturation?

Answer: They transport calcium and regulate pH to facilitate mineralization and prevent demineralization.

What structure protects enamel during eruption?

Answer: The reduced enamel epithelium (REE) protects enamel until the tooth erupts.