2 Odontogenesis

Question 1

Answer 1

Top: vestibular lamina

Bottom: primary dental lamina

Question 2

Answer 2

Primary dental lamina

Question 3

Answer 3

Primary dental lamina

Question 4

Answer 4

L: vestibular lamina

R: epithelial bud

Question 5

Answer 5

L: Epithelial bud

R: Vestibular lamina

Question 6

Answer 6

Epithelial cap

Question 7

Answer 7

Enamel knot

Question 8

Answer 8

Tooth germ (primary central incisors)

Question 9

Answer 9

Primary dental lamina

Question 10

Answer 10

Vestibular lamina

Question 11

Answer 11

1. Enamel organ
2. Dental papilla
3. Dental follicle

Question 12

Answer 12

Enamel organ

Question 13

Answer 13

Dental follicle and dental papilla.

Question 14

Answer 14

Dental papilla (ectomesenchyme)

Question 15

Answer 15

Secondary dental lamina

Question 16

Answer 16

Dental follicle

Question 17

Answer 17

? = stratum intermedium cells

Bottom: inner epithelial cells of enamel organ (undifferentiated)

Question 18

Answer 18

1/L: stratium intermedium

2/R: outer epithelial layer

Question 19

Answer 19

1/L: inner epitheilal layer

2/R: outer epithelial layer

Question 20

Answer 20

UL: primary dental lamina stage

UR: epithelial bud stage

LL: epithelial cap stage

LR: epithelial bell stage

Question 21

What term is used for the origin and formation of the tissues of teeth?

Answer 21

Odontogenesis

Question 22

Epithelial buds begin to appear in which of the following embryonic weeks?
A. Third week

B. Fourth week.

C. Fifth week

D. Sixth week

Answer 22

3rd: stomodeum appears
4th: tongue appears
5th: facial processes merge

*6th: epithelial buds for the primary lower central incisors are the first to appear.

Question 23

Which of the following is the main function of the reduced enamel epithelium?

A. Attachment
B. Lysis
C. Protection
D. Eruption

Answer 23

C. Protects enamel surface from the surrounding CT prior to the emergence of the tooth in the oral cavity.

Question 24

Which of the following are functions of Hertwig’s epithelial root sheath? (More than one correct answer.)

A. Determines root length
B. Determine root dentin outline
C. Determine thickness of cementum
D. Determines the number of root canals of a tooth

Answer 24

B & D only. D. occurs at the diaphragm stage of the sheath, before the start of root formation.

Question 25

The epithelial buds for the permanent first molars appear during which of the following time frames? A. Sixth interuterine week B. Eighth interuterine week C. Fourth interuterine month D. Fifth interuterine month

Answer 25

C. First permanent bud to appear. D. (centeral incisors at fifth interuterine month)

Question 26

Answer 26

Cementoblast Ameloblast Odontoblast

Question 27

What is the term used for the origin and formation of dentin tissue?

Answer 27

dentinogenesis

Question 28

T/F: Odontogenesis is defined as the origin and formation or development of dentin tissue from the undifferentiated cells of the germ layers of the embryo.

Answer 28

False. Odontogenesis is the origin and formation of all the tissues of teeth, not just the dentin tissues.

Question 29

The primary dental lamina appears during which of the following embryonic weeks? A.Third week B.Fourth week C.Fifth week D.Sixth week

Answer 29

D. Sixth embryonic week, primary dental lamina first appears in the anterior area and passes posteriorly as a continuous horseshoe shaped epithelial band.

Question 30

Which of the following cell types arise from the undifferentiated or stem cells of the dental follicle? A.Fibroblast B.Cementoblast C.Osteoblast D.Osteoclast

Answer 30

A. This cell type becomes a constituent of the PDL and is responsible for the synthesis and lysis of the intercellular substances of the PDL. B. This cell type becomes a constituent of the PDL and is responsible for the synthesis of cementum tissue. C. This cell type becomes a constituent of the PDL and is responsible for the synthesis of alveolar bone.

Question 31

What is the term used for the origin and formation of enamel tissue?

Answer 31

Amelogenesis

Question 32

The dental follicle of a tooth germ matures to become which of the following specific tissues of the periodontium? A. Alveolar bond B. Cementum C. Periodontal ligament D. Gingiva

Answer 32

C, PDL. The dental follicle undergoes maturation to become the PDL that continues to house the cells that arose from the stem cells of the follicle.

Question 33

Ameloblasts originate from which epithelial cell layer of the enamel organ?

Answer 33

Inner enamel epithelium

Question 34

Odontoblasts arise from undifferentiated cells of which of the following tissues? A. Enamel organ B.Dental follicle C.Dental lamina D.Dental papilla

Answer 34

D. Dental papilla, odontoblasts arise from undifferentiated cells of the dental papilla, a type of mesenchymal tissue (embryonic or young CT).

Question 35

Which mineralized tissue is the first to appear within a tooth germ?

Answer 35

Which mineralized tissue is the first to appear within a tooth germ?

Question 36

Which of the following sites are tissues of a tooth germ? A. Dental lamina B. Enamel organ C. Dental papilla D. Dental follicle

Answer 36

B. Epithelial tissue of tooth germ C. One of two mesenchymal or ectomesenchymal tissues of a tooth germ. Becomes pulp tissue of a tooth. D. One of two mesenchymal or ectomesenchymal tissues of a tooth germ. Becomes the periodontal ligament tissue.

Question 37

T/F: The secondary dental lamina arises from the oral epithelium.

Answer 37

False. It arises from the lingual side of the primary dental lamina.

Question 38

The clear or acellular layer of the tooth germ lies immediatley between which of the following two sites? A.Outer and stellate reticulum cell layers B.Outer cell layer and dental follicle C.Stratum intermedium and inner cell layers D.Inner epithelial cell layer and dental papilla

Answer 38

D

Question 39

The epithelial bud becomes the epithelial cap which becomes which of the following? A.Dental follicle B.Dental papilla C.Enamel organ D.Dental sac

Answer 39

C. The organ is shaped like a bell an dis comprised of four distinct epithelial cell layers.

Question 40

Answer 40

From top, 1. Stallate reticulum 2. Outer 3. Inner 4. Stratum intermedium

Question 41

Which of the following cells are specialized CT cells? A.Ameloblast B.Odontoblast C.Cementoblast D.Undifferentiated mesenchymal cell

Answer 41

A: No, epithelial cell specialized to secrete enamel tissue. B: Yes, CT cell specialized to produce dentin tissue. C: Yes, CT cell specialized to produce cementum tissue. D: No, not considered specialized. Pluropotential cell that develops into different types of specialized cells (cementoblast, odontoblast, osteoblast, fibroblast).

Question 42

Epithelial buds evolve directly from cells of which of the following structures? A. vestibular lamina B. Lamina propria C. Dental laminae D. Basal lamina

Answer 42

C. Dental laminae; bud signifying the site of tooth development.

Question 43

Answer 43

1. Dentin 2. Stellate reticulum layer 3. Outer cell layer 4. Inner cell layer 5. Hertwig’s root sheath 6. Dental papilla

Question 44

The four layers of the enamel organ merge to form a stratified squamous epithelial layer over the enamel surface. What is the term used for this epithelial layer? A.Sulcular epithelium B.Junctional epithelium C.Reduced enamel epithelium D.Hertwig’s epithelial root sheath

Answer 44

C. Covers and attaches to the entire surface of enamel prior to tooth emergence into the oral cavity.

Question 45

Which of the following are invaginations of the stomodeal epithelium? (More than one correct answer.) A.Sulcus terminalus B.Vestibular lamina C.Primary dental lamina D.Secondary dental laminae

Answer 45

A.No, not an invagination. Marks the junction between the anterior 2/3 and posterior 1/3 of tongue. B.Yes, solid band of epithelial cells whose middle cells die off, leaving an epithelial lined trough called the “vestibule.” C.Yes, extends as an epithelial band along the dental arches. Cells along its deep end become epithelial buds, sites of tooth development. D.No, lingual extensions from the primary dental lamina, not the stomodeal epithelium. Epithelial buds of succedaneous teeth develop at the deep end of each secondary dental lamina.

Question 46

Answer 46

1. Oral epithelium 2. Reduced enamel epithelium 3. Enamel 4. Dentin 5. Pulp

Question 47

Which of the following two cell layers of the enamel organ come together to form Hertwig’s epithelial root sheath? A.Inner and stratum intermedium layers B.Outer and stellate reticulum layers C.Inner and stellate reticulum layers D.Outer and inner layers

Answer 47

D