Midterm # 1 - GENERAL

Question 1

What are the 6 stages of tooth development?

Answer 1

1) Initiation stage
2) Bud stage
3) Cap stage
4) Bell stage
5) Stage of apposition
6) Stage of maturation

Question 2

What happens during the ‘Initiation stage’ of tooth development? And when does it occur?

Answer 2

• The oral epithelium gives rise to the dental lamina (adjacent to the ectomesenchyme)
• 6 - 7 weeks in utero

Question 3

What happens during the ‘Bud stage’ of tooth development? And when does it occur?

Answer 3

• The dental lamina grows into a bud shape, penetrating the ectomesenchyme.
• 8th week in utero

Question 4

What happens during the ‘Cap stage’ of tooth development? And when does it occur?

Answer 4

• The dental lamina continues to grow into a cap-like structure called “the enamel organ”, which surrounds the ectomesenchyme and turns into the ‘dental papilla’ and the ‘dental sac/follicle’.
• 9 - 10 weeks in uterio

Question 5

What happens during the ‘Bell stage’ of tooth development? And when does it occur?

Answer 5

• The enamel organ turns into a bell shape with 4 cell types within it. The cells in the dental papilla turn into 2 cell types.
• 11 - 13 weeks in utero

Question 6

What happens during the ‘stage of Apposition’ of tooth development? And when does it occur?

Answer 6

• Dental tissue types (enamel, dentin and cementum) are secreted in layers.
• Varies according to the tooth, but usually 4 - 5 months in utero

Question 7

What happens during the ‘stage of Maturation’ of tooth development? And when does it occur?

Answer 7

• Dental tissue types fully mineralize to mature form

- Varies according to tooth, but usually 4 - 5 months in utero

Question 8

What is a ‘tooth germ’?

Answer 8

Buds within the alveolar process (crown and dentin form first, root later)

Question 9

What are the 2 divisions of the oral cavity and what do they compose of?

Answer 9

1) Vestibular area - outer part of the mouth (inner part of lips and cheeks, facial surface of teeth)
2) Oral cavity proper - inside the mouth (backs of the front teeth to the faucial pillars)

Question 10

What are the 3 components of the Gingiva?

Answer 10

1) Marginal/free gingiva
2) Attached gingiva
3) Interdental papilla

Question 11

Describe ‘Enamel’

Answer 11

• Covers anatomical crown
• Avascular (without vessels = strong)
• Translucent (white, yellow or grey)
• Produced by ‘ameloblast cells’

Question 12

Describe ‘Dentin’

Answer 12

• Covers pulp and forms bulk of tooth
• Avascular
• Yellow
• Produced by ‘odontoblast cells’

Question 13

What are the 4 types of Dentin? Describe.

Answer 13

Mantel: outermost layer
Circumpupal: layer around outer pupal wall
Peritubular: within walls of dentinal tubules
Intertubular: between dentinal tubules

Question 14

What are the 3 classifications of Dentin? Describe.

Answer 14

Primary: forms the body of the tooth
Secondary: forms AFTER tooth eruption (teeth grinders)
Tertiary: forms in response to trauma to the pulp (caries)

Question 15

Describe ‘Cementum’

Answer 15

• Covers dentin along the root surface
• Attachment site for PDL
• Laid down by ‘cementoblasts’

Question 16

What are the 2 types of Cementum? Describe.

Answer 16

1) Acellular: cervical 1/2 (middle/neck) of root

2) Cellular: apical 1/2 of root

Question 17

Describe ‘Pulp’

Answer 17

• Innermost tissue of the tooth

- Compose of: intercellular substance, tissue fluid, lymphatics, vascular system, nerves and fibers

Question 18

What are the 2 divisions in the pulp chamber?

Answer 18

1) Coronal pulp (pulp horns): in the crown

2) Radicular pulp (pulp canal): in the root

Question 19

What are the 3 functions of pulp?

Answer 19

1) Nutrition
2) Sensory
3) Protective (secondary/tertiary)

Question 20

What is the make up (%) of Enamel?

Answer 20

96% inorganic (hydroxapatite crystals)
1% organic
3% water

Question 21

What is the make up (%) of Dentin?

Answer 21

70% inorganic (hydroxapatite crystals)
20% organic
10 % water

Question 22

What is the make up (%) of Cementum?

Answer 22

65% inorganic
23 % organic
12% water

Question 23

What are the 3 types of Dentition?

Answer 23

1) Primary/Deciduous Dentition (baby teeth)
2) Mixed Dentition (transitional)
3) Secondary Dentition (adult teeth)

Question 24

What are ‘succedaneous’ teeth?

Answer 24

Permanent teeth that replace primary teeth (all teeth EXCEPT molars)

Question 25

What are the functions of the 4 types of teeth?

Answer 25

1) Incisors: cut and bite
2) Canines: cute, tear and grasp
3) Premolars: tear and grasp
4) Molars: grind and pulverize

Question 26

What are the components of the Periodontium?

Answer 26

• Gingiva
• Cementum
• Periodontal ligament (PDL)
• Alveolar process (bone)

Question 27

Describe the types of furcations and which teeth have them.

Answer 27

Bifurcation: 2 roots (M and D)
- Maxillary 1st premolar
- Mandibular molars
Trifurcation: 3 roots (2B and 1L)
- Maxillary molars

Question 28

What is an embrasure and what does it allow for?

Answer 28

• A spillway/ V-shaped space created between 2 teeth meeting in the same arch
• Allows for natural food flow and mechanical cleansing.
• Allows enough gingival stimulation for health (protects gingiva from trauma)

Question 29

What is the difference between the embrasures in the anterior vs. the posterior?

Answer 29

• Anterior: facial and lingual are equal

- Posterior: lingual are wider than buccal (because teeth are narrower on the lingual)

Question 30

What are the horizontal divisions of crowns and roots (anterior and posterior)?

Answer 30

• Anterior crown: incisal, middle, cervical
• Posterior crown: occlusal, middle, cervical
• Root: cervical, middle, apical

Question 31

What are the vertical divisions of a tooth? (facial and proximal)

Answer 31

• Facial: mesial, middle, distal

- Proximal: facial, middle, lingual

Question 32

What are the eruption ages of primary teeth?

Answer 32

• Central incisors: 6 - 12 months
• Lateral incisors: 9 - 16 months
• Canines: 16 - 23 months
• 1st molars: 13 - 19 months
• 2nd molars: 22 - 33 months

Question 33

What are the 3 number systems?

Answer 33

1) Universal Numbering System (used in USA)
2) International Numbering System (what we use)
3) Palmer Notation Method (used in ortho)

Question 34

Describe the Universal Numbering System.

Answer 34

• Permanent: 1 - 32 (quads 1 - 4)

- Primary: A - K

Question 35

Describe the International Numbering System.

Answer 35

• Permanent: 1st number = quadrant, 2nd number = tooth (quads 1 - 4)
• Primary: (same except quads 5 - 8)

Question 36

Describe the Palmer Notation Method.

Answer 36

Symbol/bracket on each number

• Permanent: 1 - 8 (in each quad)
• Primary: A - E (in each quad)