Lecture 18: Oral Cavity + Teeth Flashcards
Types of oral mucosa
- Masticatory
- Lining
- Specialized
Masticatory mucosa
SSK/parakeratinized (outer cells retain nuclei, stains similar to SSNK otherwise). Gingiva, hard palate; chewing force/friction.
Gingiva
Aka gums. Made of masticatory mucosa and junctional epithelium
Junctional epithelium
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
Lining mucosa
Majority of oral cavity mucosa, thick SSNK. Lips, cheeks, soft palate, sublingual, mucosa around alveolar bone.
Vermilion border
Transition between SSK skin and SSNK of the lips.
Vermilion zone
Area of lips that lacks salivary glands; depends on moisture from inside the oral cavity (chapped lips)
Specialized mucosa
SSK or SSNK; has taste or mechanical functions e.g. dorsal tongue, soft palate, pharynx.
Lingual papillae types
- Filiform (cups)
- Foliate
- Fungiform (mushroom shaped)
- Circumvallate
Filiform papillae
Specialized for grasping; keratin “cups”, e.g. on cat tongues
Foliate papillae
Common on lateral dog tongue, but none on post-infant humans
Fungiform papillae
Most numerous papillae with taste buds; mushroom-shaped
Circumvallate papillae
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
How many teeth do humans have?
20 primary (baby, deciduous, milk) teeth and 32 secondary (adult) teeth
Components of tooth
- Crown (anatomical vs clinical)
- Cervix (area between crown/root)
- Root (cementum covered)
- Pulp cavity (innervated/vascularized CT)
Mineralized tissues of teeth and their origins
Ameloblasts secrete enamel
Odontoblasts secrete predentin -> dentin
Cementoblasts secrete cementum
Periodontal ligament
Dense regular CT with Sharpey’s fibers transmitting force from teeth to alveolar bone
Tooth development stages
- Dental lamina
- Cap stage
- Bell stage
- Root stage
Dental lamina stage
Invagination of oral epithelium
Cap stage
Formation of enamel organ, dental follicle, and dental papilla
Bell stage
Appearance of cervical loop (enamel, dentin, cementum junction)
Root stage
Enamel and dentin have been fully secreted already. Development of the root causes eruption
Hertwig’s root sheath
Extension of combined inner/outer enamel epithelia past cervical loop which guides root stage dentin formation
Mineralized tissue secretion order
(Pre)dentin is secreted first; this induces ameloblasts to secrete enamel onto the dentin and triggers cementoblast differentiation for cementum
Stellate reticulum
Hydrated, GAG-filled EC fluid inside the enamel organ. Fluid tension maintains shape of enamel organ and thus shape of tooth (EMT, ectoderm derived)
Inner enamel epithelium
Enamel organ epithelium furthest from oral cavity, apposed to condensed mesenchyme. Contains stratum intermedium (inner cellular layer) and pre-ameloblasts (outer cellular layer)
Outer enamel epithelium
Remainder of enamel organ epithelium beyond IEE.
Dental papilla
Dental lamina/enamel organ induces mesenchyme condensation subjacent to IEE. Later becomes odontoblasts near IEE and pulp cavity.
Ameloblast polarity
Ameloblasts of IEE induce differentiation of odontoblasts, which begin to secrete dentin apically. Ameloblasts then reverse polarity to secrete enamel apically onto dentin.
