Lecture 18: Oral Cavity + Teeth

Question 1

Types of oral mucosa

Answer 1

1. Masticatory
2. Lining
3. Specialized

Question 2

Masticatory mucosa

Answer 2

SSK/parakeratinized (outer cells retain nuclei, stains similar to SSNK otherwise). Gingiva, hard palate; chewing force/friction.

Question 3

Gingiva

Answer 3

Aka gums. Made of masticatory mucosa and junctional epithelium

Question 4

Junctional epithelium

Answer 4

Area of gingiva connecting enamel and epithelium; has modified basement that seals off outer tooth. Many hemidesmosomes between tooth enamel/internal basal lamina and CT/external basal lamina

Question 5

Lining mucosa

Answer 5

Majority of oral cavity mucosa, thick SSNK. Lips, cheeks, soft palate, sublingual, mucosa around alveolar bone.

Question 6

Vermilion border

Answer 6

Transition between SSK skin and SSNK of the lips.

Question 7

Vermilion zone

Answer 7

Area of lips that lacks salivary glands; depends on moisture from inside the oral cavity (chapped lips)

Question 8

Specialized mucosa

Answer 8

SSK or SSNK; has taste or mechanical functions e.g. dorsal tongue, soft palate, pharynx.

Question 9

Lingual papillae types

Answer 9

1. Filiform (cups)
2. Foliate
3. Fungiform (mushroom shaped)
4. Circumvallate

Question 10

Filiform papillae

Answer 10

Specialized for grasping; keratin “cups”, e.g. on cat tongues

Question 11

Foliate papillae

Answer 11

Common on lateral dog tongue, but none on post-infant humans

Question 12

Fungiform papillae

Answer 12

Most numerous papillae with taste buds; mushroom-shaped

Question 13

Circumvallate papillae

Answer 13

10-20 large ones at the back of the tongue. Lateral taste buds face an inner moat where saliva/food can accumulate. von Ebner’s glands serous secretions go to the moats

Question 14

How many teeth do humans have?

Answer 14

20 primary (baby, deciduous, milk) teeth and 32 secondary (adult) teeth

Question 15

Components of tooth

Answer 15

• Crown (anatomical vs clinical)
• Cervix (area between crown/root)
• Root (cementum covered)
• Pulp cavity (innervated/vascularized CT)

Question 16

Mineralized tissues of teeth and their origins

Answer 16

Ameloblasts secrete enamel
Odontoblasts secrete predentin -> dentin
Cementoblasts secrete cementum

Question 17

Periodontal ligament

Answer 17

Dense regular CT with Sharpey’s fibers transmitting force from teeth to alveolar bone

Question 18

Tooth development stages

Answer 18

1. Dental lamina
2. Cap stage
3. Bell stage
4. Root stage

Question 19

Dental lamina stage

Answer 19

Invagination of oral epithelium

Question 20

Cap stage

Answer 20

Formation of enamel organ, dental follicle, and dental papilla

Question 21

Bell stage

Answer 21

Appearance of cervical loop (enamel, dentin, cementum junction)

Question 22

Root stage

Answer 22

Enamel and dentin have been fully secreted already. Development of the root causes eruption

Question 23

Hertwig’s root sheath

Answer 23

Extension of combined inner/outer enamel epithelia past cervical loop which guides root stage dentin formation

Question 24

Mineralized tissue secretion order

Answer 24

(Pre)dentin is secreted first; this induces ameloblasts to secrete enamel onto the dentin and triggers cementoblast differentiation for cementum

Question 25

Stellate reticulum

Answer 25

Hydrated, GAG-filled EC fluid inside the enamel organ. Fluid tension maintains shape of enamel organ and thus shape of tooth (EMT, ectoderm derived)

Question 26

Inner enamel epithelium

Answer 26

Enamel organ epithelium furthest from oral cavity, apposed to condensed mesenchyme. Contains stratum intermedium (inner cellular layer) and pre-ameloblasts (outer cellular layer)

Question 27

Outer enamel epithelium

Answer 27

Remainder of enamel organ epithelium beyond IEE.

Question 28

Dental papilla

Answer 28

Dental lamina/enamel organ induces mesenchyme condensation subjacent to IEE. Later becomes odontoblasts near IEE and pulp cavity.

Question 29

Ameloblast polarity

Answer 29

Ameloblasts of IEE induce differentiation of odontoblasts, which begin to secrete dentin apically. Ameloblasts then reverse polarity to secrete enamel apically onto dentin.