Tooth Development

Question 1

When does tooth formation begin? What signifies the start of odontogenesis?

Answer 1

6th week . Appearance of dental lamina

Question 2

What is the primary epithelial band? where did it come from and What does it give rise to?

Answer 2

Thickened ectoderm in location of future jaws. It started as oral epithelium, became epithelial band, and became dental lamina.

Question 3

What are the abnormalities that occur during the odontogenesis initiation, or week 6?

Answer 3

1. Anodontia: Congenital absence of all teeth
2. Partial adontia: a. Hypo (1-5 missing) Oligo (>6)
3. Hyperdontia (polydontia): Extra teeth.

Question 4

What are the most common teeth to be missing?

Answer 4

Upper Lateral Incisors.

Question 5

What do dental lamina give rise to? Successional lamina?

Answer 5

Dental=Primary teeth

Successional= Permanent teeth

Question 6

What happens during the 8th week of odontogenesis? Describe the events.

Answer 6

Budding Stage.

1. Ectoderm lining stomadeam–>Oral epithelium->Dental lamina.
2. Dental lamina invaginates into ectomesenchyme.
3. Ectomesenchyme cells condense under lamina.

Question 7

What happens during the 9-10th weeks of odontogenesis? Describe the events.

Answer 7

Cap Stage

1. Bud becomes Enamel organ, forms a cap over the condensed ectomesenchyme.
2. Ectomesenchymal cells aggregate to form the dental papilla
3. Dental papilla extends around the enamel organ forming the dental follicle.
4. Outer and inner enamel epethelium and stellate reticulum form.

Question 8

What happens to the vestibular lamina? What is its fate?

Answer 8

Degenerates to give rise the the epithelial lining on and surrounding the vestibule.

Question 9

What abnormalities can occur during the cap stage?

Answer 9

1. Dens in Dente
2. Fusion (fewer # of teeth)
3. Gemination (correct # of teeth)

Question 10

What happens during the 11th-12 week of odontogenesis? Describe the events

Answer 10

Bell Stage.

1. Dental Lamina disintegrates
2. Morphodifferentiation
3. Histodifferentiation.
4. Deepening of the undersurface of enamel organ.

Question 11

What is considered the tooth germ?

Answer 11

Enamel organ, Dental Papilla, and Dental follicle

Question 12

The peripheral cells of the dental papilla differentiate into what?

Answer 12

Odontoblasts.

Question 13

The inner cells of the dental papilla form what?

Answer 13

The pulp.

Question 14

What is the cervical root? Also called the?

Answer 14

Where the inner and outer enamel epethelia meet. Called Hertwigs Epithelial Root Sheath.

Question 15

How are crown patterns and number of cusps established?

Answer 15

By the folding of the Inner Enamel Epithelium.

Question 16

Persistent fragmentation of the dental lamina may create what?

Answer 16

Epithelial pearls, or Rests of Serres.

Question 17

What are enamel knots? Other name?

Answer 17

Control center for inner enamel epithelium folding for cusps. AKA: Ahren’s Knot

Question 18

Enamel cord associated with?

Answer 18

Placement of first cusp.

Question 19

What are some abnormalities that can occur at the bell stage?

Answer 19

1. Microdontia (peg lateral)
2. Macrodontia
3. Amelogenesis Imperfecta (enamel formation fails)
4. Dentinogenesis imperfecta (dentin formation fails)