Teeth

Question 1

What are the parts of the tooth and what are the tissues of the tooth?

Answer 1

Parts: crown and root

Tissues: enamel, dentin and pulp

Question 2

What is the anatomical crown and what is the clinical crown?

Answer 2

Anatomical: the part covered by enamel
Clinical: The part visible in the oral cavity

Question 3

What is the function of the enamel?

Answer 3

To protect the teeth from stress during mastication

Question 4

What type of cells produce enamel?

Answer 4

Ameloblasts/adamantoblasts. The cells are of ectodermal origin.

Question 5

What are the ratio of inorganic and organic matter in enamel?

Answer 5

98% inorganic, 2% organic

Question 6

What is the major inorganic component of enamel?

Answer 6

Calcium and phosphate, forming apatite crystals Ca10(OH)2(PO4)6

Question 7

Name the organic components of enamel

Answer 7

Proteins, carbohydrates, lipids, citrates, water

Question 8

What type of cells produce dentin?

Answer 8

Odontoblasts (neural crest origin)

Question 9

What are the inorganic components of dentin?

Answer 9

Calcium, phosphate, magnesium, carbonate sodium, chloride, fluor

Question 10

What are the organic components of dentin?

Answer 10

Collagen (I and V), proteoglycans, phosphophorine, phospholipids, cholesterin

Question 11

Where in a histology slide can you find odontoblasts?

Answer 11

In the outer surface of the dental pulp

Question 12

What are Tomes fibers?

Answer 12

Odontoblast cytoplasmic processes

Question 13

What is primary dentin?

Answer 13

A dentin formed before the completion of the apical forarmen of the root. Primary dentin has regular patterns of tubules.

Question 14

What is secondary dentin?

Answer 14

A dentin formed after the completion of the apical forarmen and continues to form through the life of the tooth.

Question 15

What is tertiary dentin?

Answer 15

It is formed as a reaction to external stimulation, such as cavities. There are two types of tertiary dentin:

• reactionary
• reparative

Question 16

What is the primary function of the pulp?

Answer 16

The primary function if formative; it gives rise to odontoblasts that not only form dentin, but also interact with dental epithelium early in tooth development to initiate the formation of enamel.

Question 17

What is the secondary function of the pulp?

Answer 17

Sensitivity, hydration and defense.

Question 18

How many teeth does an adult have?

Answer 18

32

Question 19

How many teeth does a child have?

Answer 19

20

Question 20

How many teeth are in a quadrant of an adult?

Answer 20

8.

1 central incisor
1 lateral incisor
1 canine
2 premolars
3 molars

Question 21

How many teeth are in a quadrant of a child?

Answer 21

5.

1 central incisor
1 lateral incisor
1 canine
2 molars

Question 22

What are the three phases of teeth development?

Answer 22

1. Initiation
2. Morphogenesis
3. Histogenesis

Question 23

What happens during initiation?

Answer 23

The sites of the future teeth are established with the appearance of tooth germs along an invagination of the oral epithelium called the dental lamina.

Question 24

What happens during morphogenesis?

Answer 24

The shape of the tooth is determined by a combination of cell proliferation and cell movement.

Question 25

What happens during histogenesis?

Answer 25

Differentiation of cells to form dental tissues, both mineralized (enamel, dentin, cementum) and unmineralized (dental pulp, periodontum)

Question 26

When does tooth formation first occur?

Answer 26

Tooth formation occurs in the 6th week of intrauterine life with the formation of the primary epithelial band

Question 27

During 7th week the epithelial band divides into two. What?

Answer 27

A lingualy located process called the dental lamina. This will contribute to the development of the teeth. A buccally located process called the vestibular lamina. This will contribute to the formation of the vestibule of the mouth (lips and cheeks).

Question 28

All deciduous teeth (milk teeth) arise from what?

Answer 28

The dental lamina

Question 29

The primitive oral cavity (stomodeum) is lined by stratified squamous epithelium called ...?

Answer 29

Oral ectoderm

Question 30

The oral ectoderm contacts the endoderm of the foregut to form the ...?

Answer 30

Buccopharyngeal membrane

Question 31

Most of the connective tissue cells underlying the oral ectoderm are of what origin?

Answer 31

Ectomesenchyme

Question 32

When does the early cap stage begin?

Answer 32

Week 11

Question 33

What happens at the early cap stage?

Answer 33

The enamel organ invaginate to form a cap-shaped structure

Question 34

In the cap stage, what do we call the epithelia of the enamel structure?

Answer 34

External enamel epithelium and internal enamel epithelium

Question 35

When does the late cap stage begin?

Answer 35

Week 12

Question 36

The central cells of the enamel organ separate during late cap stage to form a tissue called ...?

Answer 36

Stellate reticulum

Question 37

In the late cap stage what are the cell shapes of external and internal enamel epithelium?

Answer 37

External enamel epithelium: cuboidal | Internal enamel epithelium: columnar

Question 38

The mesenchyme lying beneath the internal enamel epithelium is termed the ... ?

Answer 38

Dental papilla

Question 39

The mesenchyme surrounding the tooth germ is termed the ...?

Answer 39

Dental follicle

Question 40

When does the early bell stage begin?

Answer 40

Week 14

Question 41

How does the external enamel epithelium cells communicate with each other?

Answer 41

Through desmosomes and gap junctions

Question 42

What happens at the cervical loop?

Answer 42

The cervical loop is at which there is considerable mitotic activity. It lies at the growing margin of the enamel organ where the external enamel epithelium is continuous with the internal enamel epithelium.

Question 43

When is the stellate reticulum most fully developed?

Answer 43

At the bell stage

Question 44

In histological sections, what does the stellate reticulum look like?

Answer 44

The cells are star-shaped with bodies containing nuclei and many branching processes. It looks as if the cells are separated, but they communicate through desmosomes and gap junctions.