Root Development

Question 1

What structure is responsible for root development?

Answer 1

Cervical loop

Question 2

What does the cervical loop consist of?

Answer 2

IEE (inner enamel epithelium) and OEE (outer enamel epithelium)

Question 3

How is Hertwig’s epithelial root sheath formed?

Answer 3

The cervical loop elongates away from the crown enclosing more dental papilla.

Question 4

Why isn’t enamel formed in the root if you have IEE and OEE?

Answer 4

The other cell linings are not present (Stellate reticulum and stratum intermedium) so the body recognizes this and will not form enamel.

Question 5

What are the functions of Hertwig’s epithelial root sheath?

Answer 5

1. Induction of Odontoblasts
2. Determines size, shape, and # of roots.
3. After roots are completed the sheath disintegrates and becomes “epithelial rests of Malassez”

Question 6

How is cementum formed in the root?

Answer 6

1. Disintegration of HERS.
2. Contact b/w undifferentiated mesenchymal cells with newly formed dentin.
3. Immature cementoblasts
4. Secretion of a matrix called cementoid
5. Maturation of the matrix (hydroxyapatite) where cementoblasts are trapped and become cementocytes which eventually become cementum

Question 7

What is HERS?

Answer 7

Hertwig’s epithelial root sheath.

Question 8

What is the origin of the periodontal ligament?

Answer 8

Ectomesenchyme from the dental sac.

Question 9

How is the PDL formed?

Answer 9

1. Collagen fibers are organized into bundles.

2. The ends of the groups insert into the outer cementum and surrounding alveolar bone.

Question 10

True of False; The PDL makes humans theocodonts.

Answer 10

True

Question 11

What is the name for a special ligament attachment from root to bone?

Answer 11

gomphosis