Early Tooth Development (Larsen 2)

Question 1

Two tissues required by odontogenesis

Answer 1

• Oral ectoderm (epithelium)

- Ectomesenchyme (dental mesenchyme) (connective tissue)

Question 2

Oral ectoderm

Answer 2

Oral epithelium that forms enamel organ

Question 3

Ectomesenchyme (dental mesenchyme)

Answer 3

• Connective tissue
• Neural crest origin
• Forms dentin and pulp of both crown and root

Question 4

Life cycle of a tooth

Answer 4

• Growth (Initiation, Proliferation, Morphodifferentiation, Histodifferentiation, Apposition [adjacent but different, like enamel and dentin])
• Calcification/Mineralization
• Eruption
• Attrition

Question 5

Initiation: ______ is the first sign of tooth development, is a horseshoe-shaped thickening of the oral epithelium, and develops around 6 weeks in utero.

Answer 5

Dental lamina

Question 6

Initiation: The _____ is an epithelial thickening that forms along ten specific points called ______ on both the mandibular and maxillary arches.

Answer 6

• Tooth bud

- Dental placode (becomes specific teeth)

Question 7

Tooth bud stage: oral epithelium grows down into the _____.

Answer 7

Ectomesenchyme

Question 8

Tooth bud stage: growth of oral epithelium becomes bulbous and resembles a ____.

Answer 8

Boot

Question 9

Tooth bud stage: mitosis takes place on _____ and _____ causing a ______.

Answer 9

• Superior surface
• Distal tip
• Concavity

Question 10

Tooth bud stage: oral epithelium will form _____.

Answer 10

Enamel

Question 11

Tooth bud stage: Ectomesenchyme in cavity will become ______.

Answer 11

Dental papilla

Question 12

Steps from dental lamina to tooth bud

Answer 12

• Dental lamina
• Elongation
• Tooth bud

Question 13

In the cap stage, cells become ____ and ____ different.

Answer 13

• Functionally

- Morphologically

Question 14

Outer Layer of the Enamel Organin Cap Stage (Outer enamel epithelium)

Answer 14

Single layer of cuboidal epithelium along the convexity of the cap

Question 15

Inner Layer of the Enamel Organ Cap Stage (Inner enamel epithelium)

Answer 15

Single layer of low columnar cells along the concavity of the cap

Question 16

Middle Layer of the Enamel Organ Cap Stage (Stellate reticulum)

Answer 16

Stellate shaped cells separated by glycosaminoglycans

Question 17

Dental Papilla in Cap Stage: _______ in the concavity underneath the ______.

Answer 17

• Ectomesenchyme

- Inner enamel epithelium

Question 18

Dental Papilla in Cap Stage: Forms the _____ and ____ of the crown

Answer 18

• Dentin

- Pulp

Question 19

Dental Sac or Follicle in Cap Stage: ______ surrounding the developing enamel organ and dental papilla

Answer 19

Ectomesenchyme

Question 20

Dental Sac or Follicle in Cap Stage: Will form ______, ______, and ______.

Answer 20

• Cementum
• Periodontal ligament
• Alveolar process

Question 21

Cervical Loop in Cap Stage: ______ rim of the enamel organ formed by ______.

Answer 21

• Outer

- Outer and inner enamel epithelium

Question 22

Cervical Loop in Cap Stage: Is later involved in ______ formation.

Answer 22

Root

Question 23

Cap Stage Summary: Proliferation of growth by mitosis of ______ cells resulting in _____ morphology.

Answer 23

• Epithelial

- Concave

Question 24

Cap Stage Summary: Three layers in the enamel organ

Answer 24

1. Outer enamel epithelium
2. Inner enamel epithelium
3. Stellate reticulum

Question 25

Cap Stage Summary: _______ at the outer rim of the enamel organ

Answer 25

Cervical loop

Question 26

Cap Stage Summary: Ectomesenchyme forms _______.

Answer 26

Dental papilla

Question 27

Cap Stage Summary: ______ surrounds enamel organ and dental papilla

Answer 27

Dental sac

Question 28

Shaping of the tooth such as incisor or molar

Answer 28

Morphodifferentiation

Question 29

Differentiation of ameloblasts from the inner enamel epithelium

Answer 29

Histodifferentiation

Question 30

Differentiation begins at the ______ and moves ______.

Answer 30

- Cuspal tip | - Cervically

Question 31

Differentiation of odontoblasts from the dental papilla

Answer 31

Histodifferentiation

Question 32

Name and describe the inner layer of the bell stage enamel organ

Answer 32

Inner enamel epithelium - columnar cells that form ameloblasts

Question 33

The ______ is a cluster of non-dividing epithelial cells that orchestrates cuspal morphogenesis.

Answer 33

Enamel knot

Question 34

Name and describe the outer layer of the bell stage enamel organ

Answer 34

Outer enamel epithelium - Avascular (fed by blood vessels in follicle)

Question 35

Name the new layer of the bell stage enamel organ

Answer 35

Stratum intermedium

Question 36

The ______ is composed of two to three layers of cells on the surface of the inner enamel epithelium and is the nutritional layer needed for the formation of enamel.

Answer 36

Stratum intermedium

Question 37

Name and describe the middle layer of the bell stage enamel organ

Answer 37

Stellate reticulum - continued secretion of GAGs to allow growth of the crown

Question 38

Dental papilla in bell stage

Answer 38

- Odontoblasts | - Dental Pulp

Question 39

Describe odontoblasts of dental papilla in bell stage

Answer 39

Terminally differentiated cell; cells next to the basement membrane start secreting the organic matrix of mantle dentin

Question 40

Describe the dental pulp of dental papilla in bell stage

Answer 40

The central portion of the connective tissue also contains the blood vessels and nerves

Question 41

The bell stage dental sac or follicle is composed of _______ of neural crest origin and forms ____, _____, and ____.

Answer 41

-Ectomesenchyme -Periodontal ligament -Cementum Alveolar process

Question 42

The bell stage ______ is where the inner enamel epithelium and the outer enamel epithelium meet.

Answer 42

Cervical loop

Question 43

The _____ will be involved in the formation of the root after the crown has fully formed.

Answer 43

Cervical loop

Question 44

In the bell stage, the cells of the ______ continue to divide.

Answer 44

Cervical loop

Question 45

Crown Formation: the inner enamel epithelium is constrained between the ______ and _____.

Answer 45

- Cervical loop | - Cusp tip

Question 46

Crown Formation: ______ forms as a result of cell proliferation

Answer 46

Cuspal outline

Question 47

Crown Formation: Future cusp is pushed up toward the _______.

Answer 47

Outer enamel epithelium

Question 48

Bell Stage Summary: Four layers of the enamel organ

Answer 48

1. Outer enamel epithelium 2. Inner enamel epithelium, ameloblasts 3. Stellate reticulum 4. Stratum intermedium (NEW)

Question 49

Bell Stage Summary: Two layers of dental pulp

Answer 49

1. Dental papilla | 2. Odontoblasts (NEW)

Question 50

Bell Stage Summary: Cell surrounding enamel organ and pulp

Answer 50

Dental sac or dental follicle

Question 51

______ is a thickening of oral epithelium lateral to dental lamina in which cells grow downward into the connective tissue and degenerate forming a cavity.

Answer 51

Vestibular lamina

Question 52

______ is an extension of the dental lamina lingual to the primary tooth and forms ___ of the permanent teeth.

Answer 52

- Successional lamina | - 20

Question 53

Parent dental lamina

Answer 53

Remains of the original lamina

Question 54

Lateral lamina

Answer 54

Connects developing primary tooth to parent lamina

Question 55

Permanent molars are derived directly from the distal portion of the _______ without a primary tooth precursor.

Answer 55

Dental lamina

Question 56

Successional lamina is _____ to primary tooth.

Answer 56

Lingual

Question 57

Degeneration of the Parent Dental Lamina: During the bell stage the enamel organ loses contact with the ________ when the parent (general) lamina degenerates, which may leave islands of epithelial cells in the connective tissue.

Answer 57

Oral epithelium