10: Oral Cavity And Teeth

Front 1

Parts of the Lip

Back 1

1) ORAL MUCOSA
- Stratified Squamos Nonkeratinized epithelium in Lining Mucosa (THICK)
- Stratified squamos PARAKERATINIZED in MAsticatroy mucosa - (thinner)
**thin mostly under mouth and tongue for max absorption
- NO SUBMUCOSA OR MUSCULARIS MUCOSAE BUT SKELETAL MUSCLE PRESENT!
- Minor Salivary Glands/Labial Glands in lamina propria: mixed seromucous glands
1) keep mucous membrane moist
2) contribute to moistening of the food
3) provide an aqueous solvent necessary for taste sensation

2) VERMILLION BORDER:
- Stratified Squamos KERATINIZED epithelium
- highly vascularized (close to surface): shunting of blood to lips - red lips vs. in cold, blue lips
- Tall dermal PAPILLAE: increased surface area for attachment between epidermis and dermis - important because this area is subject to frictional forces

3) CUTANEOUS:
- Stratified Squamos KERATINIZED epithelium
- Sebaceous Glands in Lamina Propria with associated Hair Follicle

Front 2

Obicularis Oris Muscle

Back 2

Skeletal muscle surrounding orifice of the oral cavity

Front 3

Functions of Oral Cavity

Back 3

1) Digestion -
-Mechanical: mastication
-Chemical: Amylase (alpha 1, 4 linkages of starch - amylose & amylopectin) from Salivary Glands

2) Propulsion - tongue: deliver food to oral pharnx and esophagus by swallowing

Front 4

Ginigva:

Back 4

-PARAKERATINIZED epithelium: no stratum granulosum and stratum corneum has some nuclei
- HEMIDESMOSOMES - between surface parakeratinized epithelium of gum and the enmael of the tooth:
*anchorage!
- Lamina Propria: TALL CONNECTIVE TISSUE PAPILLA - strengthens attachment between epithelium and underling CT
*impt because subject to frictional forces when chewing

Front 5

Tongue

Back 5

- NO MUSCULARIS MUCOSAE: loose CT of lamina connects with dense CT of submucosa
**VON EBNER GLANDS - Serous glands (only minor gland not mixed serous mucous) -
- secrete into moat of VALLATE PAPILLAE
**Mucous glands

- Muscularis Externa - Tri Orthogonal Arrangement of skeletal muscle

- Dorsal Tongue: stratified squamose or parakeratinized epithelium EXCEPT parts with fungiform and Vallate papillae
-Ventral Tongue: nonkeratinized lining

- DORSAL AND VENTAL SURFACES HAVE PROJECTIONS CALLED PAPILLAE: (4 types!!)

1) Fillfiorm: each tip has severa keratinized projections along DORSAL surface - catches food, most abundant type!

2) Fungiform: UNkeratinized epithelium with taste buds on DORSALl surface. Mostly INTERSPERSED with filiform papillae

3) Vallate (Circumvallate): UNkeratinized epithelium in POSTERIOR tongue (run across
- most taste buds present LATERAL!
- V shaped: faces moat like trench at base: where VON EBNER's glands SECRETE into!!
- larger than other (1-2mm in diameter)

4) Foliate Papillae: leaf-like located along SIDE of tongue

Front 6

Taste Buds

Back 6

- spheroid to ovoid in nature

3 Specialized Epith. Cell Types:
1) Neurosensory: contain microvilli that project into the taste pore
- MICROVILLI have transmembrane receptors that caue cells to respond to 5 different taste qualities: sweet, sour, bitter, salty, unami
**taste quality - olfactory VS taste: a function of RECEPTORS ACTIVATED
**hot and spicy are free nerve endings in mouth

2) Supporting cells

3) Dark Basal Stem Cells: remake new neurosensory and supporting cells every 10 days.
**if mitotic division lost, we'd get disruption in our taste sensation
**renewing requires: 1) newly born sensory cells have proper recetors and 2) REWIRING of synatpic contacts o innervating afferent fibers from dengenerating to newborn neurosensory cells

Front 7

Salivary Glands

Back 7

MAJOR salvary glands: COMPOUND GLANDS!!
located OUTSIDE of lamina propria/Submucosa and secrete into oral cavity via LARGE EXCRETORY Ducts
(Acinus -> INTRALOBULAR DUCTS: (Intercalated Duct -> Striated Duct) -> INTERLOBULAR DUCT (Secretory Duct) -> Oral Cavity
- 3 types: Parotid, Sublingual, Submandibular

MINOR salivary glands:
located IN lamina propria/submucosa and secrete into oral cavity via SHORT ducts
- in cheeks, lips, tongue, soft palate, and floor of mouth
- ALL MIXED SEROUS EXCEPT VON EBNER's in TONGUE that associate with vallate papillae

**HAVE MYOEPITHELIAL CELLS AROUND GLANDS!

Front 8

Parotid Gland

Back 8

- behind ear

- 2nd highest in duct system

- PURE SEROUS glands

Front 9

Sublingual Gland

Back 9

- LEAST EXTENSIVE DUCT SYSTEM: glands in tubular stuctures to reach short ducts

- mixed serous/mucous but mainly MUCOUS

- beneath tongue in floor of mouth near symphysis of mandible

Front 10

Submandibular:

Back 10

- mixed serous/mucous but MAINLY SEROUS (DISTINCT SEROUS DEMILUNES

- beneath mandible and muscles that form floor of mouth
- on either side of midline

-MOST EXTENSIVE DUCT SYSTEM = TUBULARACINAR COMPOUND GLAND!

Front 11

Saliva

Back 11

- Hypotonic fluid due to Striated Ducts: reabsorbing Na+ and Cl-.

FUNCTION:
- secrete Water, electrolytes, amylase, and mucus for:
1) LUBRICATE FOOD - 1st steph in physical digestion
2) MEDIATE TASTE
3) STARCH DIGESTION
4) CLEANSE MOUTH
5) DILUE NOXIOUS STIMULI
6) HEALTH OF ORAL CAVITY: lysozyme and antibodies are 1st line of defense of GI tract

CONTENTS:
1) amylase
2) Epidgermal Growth Factor
3) Lysozyme
4) Antibodies - IgA from B lyphocytes TAKEN UP by the serous cells
5) lingual Lipase - Lipolysis for TAG
6) Lactoferrin
7) Lingual Antimicrobial Peptide

Front 12

TOOTH

Back 12

1) CROWN
- Anatomical Crown: ENTIRE ENAMEL (including overlap with gingiva) + DENTIN
vs. Clinical Crown - only enamel (no gingiva) + dentin
- DISTAL END

2) ROOT:
- CEMENTIN + DENTIN area
- APICAL END

Front 13

Pulp Cavity/Root Canal

Back 13

- surrounded by ODONTOBLAST LAYER!

- DENTAL PAPILLAE -> formed from mensenchymal cells encroaching on Internal Enamel during Cap stage -> PULP CAVITY/ROOT CANAL!

- VASCULARIZED CT: full of CT, Blood vessels, nerves

Apical end: tip of root where nerves and blood vessels enter pulp cavity

- CONTAINS ODONTOBLASTS WITH LONG PROJECTIONS THROUGH DENTIN = DENTINAL TUBULES: provide minerals and nutritents to Dentin to keep it alive (dentin avascular!!)

Front 14

Dentin

Back 14

- Avascular

- get nutrients from Osteoblasts in pulp cavity through dentinal tubules

- formed from Dental Papillae (pulp cavity) that make odontoblasts -> predentin -> dentin
**ODONTOBLASTS PUSHED FROM OUTSIDE to IN!!
=Odontoblasts initiate formation by EXRETING PREDENTIN at the location of overlying epithelial tissue
=Odontoblasts pushed towards pulp cavity, NARROWING CAVITY, as dentin grows

- MAKES UP MOST OF OUR TOOTH! CONSTANTLY BEING MADE!!

Front 15

Cementum

Back 15

- AVASCULAR: gets nutrients for peridontal ligament connected via SHARPEY's FIBERS (also to anchor tooth in place)
**RELY ON CEMENTOCYTES: but cementocytes only on some parts
- THICHKER CEMENTUM NEAR APEX: EMPTY LACUNAE BECAUSE CEMENTOCYTES DIED - ACEULLAR CEMENUTUM
vs.
-THINNER CEMENTUM CLOSER TO TOP OF ROOT: cementocytes still alive so can receive gasses and nutrients from Periodontal ligament

- APPOSITIONAL GROWTH: also produces in INSIDE-OUT manner like enamel WHILE DENTIN IS BEING MADE AT APEX (BASE)
**stimulated synthesis from CEMENTOCYTES when pre-dentin reaches dental sac (CT sac around developing tooth - made from surrounding mesenchyme)

Front 16

Enamel

Back 16

- Made from inner enamel epithelium -> ameloblasts -> make enamel
**made in response to odontoblasts making pre-dentin

-INSIDE OUT SYNTHESIS (from dentin-enamel border)
**Synthesis stimulated from Odontblasts making pre-dentin

- CAN NOT BE REMADE IN AFTER MATURE DEVELOPMENT BECAUSE AMELOBLASTS LAYER IS LOST!!
**lost throughout life by abrasion

**Most mineralized and HARDEST TISSUE IN BODY!

Front 17

Neural Crest Cells

Back 17

INDUCING CELLS FROM NEURAL CREST ORIGIN IN DENTAL LAMINA STAGE ->

Mesenchymal cells:
MAKE:
1) odontoblasts
2) dental sac
3) dental papilla

Front 18

Dental Sac

Back 18

OUTER CT SAC = well vascularized Membranous capsule formed from mesenchyme surround developing tissue

WILL FORM:
1) periodontal ligament
2) cementum

Front 19

Bone

Back 19

Vascular

- connected to periodontal ligament via Sharpey's fibers

Front 20

Periodontal Ligament:

Back 20

WELL VASCULRIZED thick collagen fibers extending from alveolar bone to cementum of tooth

- ANCHORS TOOTH TO BONE!!
(bone ->ligament -> cementum of tooth!)

- Periodontal Disease = Gum disease: wearing down of gum so bacteria can reach periodontal ligament - so teeth not anchored as well to bone!
**tissues holding bone, gum and teeth destroyed!!

vs. Gingivitis: inflammation of Gums due to bacteria forming plaques --> NO BONE OR TISSUE ANCHORING TOOTH LOST!

Front 21

Stellate Reticulum

Back 21

- interior of epithelial sac during growth development
- star like shaped epithelial cells due to innermost epithal cells being stretched apart
- SURROUNDED BY:
1) OUTER ENAMEL EPITHELIAL
2) DEPPER INNER ENAMEL EPITHELIAL

Front 22

Inner Enamel Epithelium

Back 22

- coumnar cells along basement mebrane -> ameloblasts

Front 23

Dental Lamina:

Back 23

signals initial stage of developement -

- formed from primitive oral epithelium invagination
- will connect to form the enamel organ but will deenerate in bell stage

Front 24

Neural Crest Tissue

Back 24

neural crest tissue -> INDUCING CELLS --> mesenchyme -> dental papilla

*DENTAL LAMINA STAGE: starts 1st stage of tooth development when oral epihtelium invaginates over it

Front 25

Enamel organ:

Back 25

1) external enamel epithel.
2) stellate reticulum
3) statum inetermedium
4) ameloblasts (internal enamel)

Front 26

Tooth Germ

Back 26

1) Enamel organ (what surrounds enamel??)
-External Enamel epithelium
-Stellate Reticulum
-Stratum intermedium
-Ameloblast Layer - previously Internal Enamel epithelium

2) Odontoblasts
3) Dental Pulp: Connective tissue with capillaries

**DOT NOT INCLUDE ENAMEL OR DENTIN!!

Front 27

Stratum Intermedium

Back 27

CAPS INSIDE SURFACE of AMELOBLASTS (adjacent to stellate reticulum!)

- concentrate mineral for enamel production

-

Front 28

Tooth Development

Back 28

1) BUD STAGE/DENTAL LAMINA STAGE

2) CAP STAGE: inward growth of inner enamel epithelium forms cap located superficial to dental papillae

3) BELL STAGE: inner enamel epihtelium invaginated into enamel organ being pushed by expanding dental papilla
**DEGENERATING DENTAL LAMINA!
- INTERNAL ENAMEL EPITHEL. -> become COLUMNAR EPITHEL. CELLS: AMELOBLASTS -> 2 FUNCTIONS
1) stimulate differentiation of odontoblasts from mesenchymal cell (ODONTOBLASTS SYNTHESIS)
2) produce ENAMEL IN RESPONSE TO ODONTOBLASTS MAKING PREDENTIN

**amyloblasts make odontoblasts which will make dentin which will act on amyloblasts to make enamel

Front 29

Masticatory Mucosa

Back 29

1) Gingiva
2) Hard Palate
3) Dorsal surface of tongue
**surfaces where most abrasive forces are = STRATIFIED PARAKERATINIZED EPITHELIUM

Front 30

Lining Mucosa

Back 30

1) internal surface of lips
2) internal surface of cheeks
3) floor of mouth
4) underside of tongue
5) soft palate
**STRATIFIED SQUAMOS NON KERATINIZED EPITHELIUM
--> Thickness varies from region to region: Thinner under tongue and on floor of mouth = MORE PERMEABLE than other regions of oral cavity

**NO MUSCUALRIS MUCOSE/MUSCULARIS EXTERNA!