Oral Cavity

Question 1

4 Main Components of the Tooth

Answer 1

• Enamel - covers crown (mainly hydroxyapatite - Ca phos crystal but no collagen like bone)
• Dentin - mineralized collagen connective tissue under enamel; flexible support of crown
• Cementum - bone-like substance that covers/protects dentin where it enters root; most soft/porous
• Pulp - central tooth; soft connective tissue w/ blood vessels and nerves

Question 2

3 Structures that Support the Tooth

Answer 2

• Gingiva - stratified squamous epithelium + lamina propria connective tissue that covers jaw bones and attaches to teeth at gum line (via basal lamina and hemidesmosomes)
• Peridontal Ligament - attaches cementum to bone to anchor teeth into jaw
  - Fibroblasts, osteoblasts, cementoblasts, macrophages, nerves (source of new bone cells when teeth moves within bone - braces or eruption)
• Alveolar Bone - forms sockets around teeth

Question 3

Gingivitis v Peridontitis

Answer 3

• Gingivitis - bacterial plaque –> inflamed gums but epithelial attachments are fine
• Peridontitis - once damage to epithelial barrier

Question 4

Symptoms of Peridontitis (8)

Answer 4

• Gingival redness and swelling
• Plaque (bacterial biofilm) –> tartar (mineralized)
  
  • Normal bacteria = gram pos, aerobic cocci THEN once deeper gum pockets it becomes gram neg, anaerobic rods like porphyromonas gingivalis
• Spont gum bleeding or w/ brushing
• Deeper crevices b/n tooth and gingiva –> peridontal pockets (>3 mm)
• Halitosis - anaerobic bacteria produce sulfur-containing gases –> bad breath
• Root exposure as gingiva recedes
• Bone loss –> inc tooth mobility and eventual migration –> mastification problems
• Bone abscesses and tooth loss

Question 5

Why treat w/ doxycycline?

Answer 5

in low doses it acts as MMP inhibitor

Question 6

How does peridontitis lead to inflammation? (3 mechanisms)

Answer 6

• Production of local cytokines (IL-1, TNFalpha) and MMPs which further degrade epithelial attachments
• TNFalpha –> inc RANK-ligand which binds RANK on osteoclasts –> bone resorption
• Molecular mimicry - antibodies against GroEL react against endogenous human hsp60

Question 7

How does P gingivalis specifically worsen inflammation?

Answer 7

• P ging also directly makes LPS –> activates osteoclasts

- P ging also makes gingipain protein –> degrades OPG –> inc osteoclast differentiation

Question 8

How does peridontitis relate to CVD? Pregnancy?

Answer 8

• CVD - some p. gingivalis in atherosclerotic plaques
  
  • P ging –> upregulation of toll-like receptors –> inflam cytokines –> thicker intima and loss of media if also have hyperlipidemia
• Pregnancy - P ging –> PGE2 –> premature creation of gap junctions in uterus –> premature births
  
  • Also, hormonal flux of pregnancy inc risk of developing oral plaques to begin with

Question 9

3 Major Salivary Glands

Answer 9

• Parotid - all serous; encapsulated and composed of irregular lobules divided by septa
• Submandibular - serous > mucous; also encapsulated w/ septa and irregular lobules
• Sublingual - mucous > serous; has septa and lobules BUT not encapsulated

Question 10

3 Types of Salivary Ducts

Answer 10

• Intercalated Ducts - SMALL and embedded right in acini; simple cuboidal epithelium; secrete antibacterials
• Striated/Secretory Intralobular Ducts - same size as secretory acinus; many basal mito and basal ion pumps hence the striations; also embedded right in acini
• Excretory Ducts - LARGE diameter; stratified cuboidal or stratified columnar right in connective tissue septa

Question 11

What are myoepithelial cells?

Answer 11

• scattered around outside of acinar epithelium; these are stimulated by parasympathetic NS –> contract –> release of secretions

Question 12

Serous v. Mucous Acini

Answer 12

• Mucous - lighter on histo w/ flat basal nuclei; secrete mucous
• Serous - darker on histo w/ round nuclei; secrete enzymes and IgA

Question 13

3 Types of Papillae

Answer 13

• Filiform - kertinized peaks in rows; help in mastification but no taste buds
• Fungiform - look like smooth mushrooms; scattered; have taste buds on their sides
• CIrcumvallate - large; form V in back of tongue; smooth keratinized surface w/ deep sulcus of taste buds and serous glands
  - von Ebner’s glands for flushing

Question 14

3 Cell Types in Taste Buds

Answer 14

• Neuroepithelial cells - have receptors and dark nuclei
• Sustentacular cells - support cells; secrete glycoaminoglycan to flush; pale euchromatic nucleus
• Basal cells - precursors