Lect 7 Teeth

Question 1

enamel

Answer 1

2-2.5 mm at thickest
95-98% by wieght inorganic
almost all hydroxyapatite crystals with trace amounts of proteins

Question 2

enamel rod

Answer 2

PRIMARY STRUCTURAL UNIT of enamel
very homogenous
may be referenced as prism
about 5 million in small tooth
12 million in large tooth
WIDER at surface of tooth compared to DEJ (2-3X as large)
flares uninteruptedly from DEJ to surface, not perfectly straight

Question 3

cross section of enamel rods

Answer 3

tail like, mostly round but not perfect w/ out shealth made of water and protein (called interrod substance) = space between interpacked rods

Question 4

apatite crystalites

Answer 4

millions per rod

Question 5

amelogenisis

Answer 5

ameloblasts

start at DEJ; move outwardly

Question 6

pulp dentin complex

Answer 6

intimately connected

odontoblasts are in pulp

Question 7

dentin

Answer 7

most tooth is dentin
resilient support of enamel
sensitive and conductive
porous
dynamic
similar radioopacity to bone
No DEJ on root; dentin to cementum

Question 8

dentin tubules

Answer 8

taper as they approach the DEJ (smaller at DEJ compared to pulp interaction)
branch into the periphery anastomose - when a branch begins to communicate with another tubule

Question 9

peritubular dentin

Answer 9

dentin surrounding tubules (more peritubular dentin closer to pulp)

Question 10

intertubular dentin

Answer 10

dentin filling spaces between tubules (more intertubular dentin closer to DEJ)
3 components: collagen, small hydroxyapatite, H2O
its hard to bond to dentin bc it contains 3 components
lots of type 1 collagen, inorganic matter in dentin intertwines, lacks organization
contains random organization of samll hydroxyapatite, and H2O

Question 11

dentinal fluid

Answer 11

water in the tubules

surround odontoblast cellular process (both within tubule)

Question 12

whats in a tubule?

Answer 12

odontoblasts are always present as long as the tooth is vital

Question 13

odontoblast

Answer 13

one cell body in inner part of dentin (outer part of pulp)

one cell process per tubule

Question 14

dentin histology

Answer 14

morphology is much different near pulp compared to enamel, heterogenous, more mineral in peritubular dentin compared to intertubular dentin
50% inorganic, 5-25% water, 5-25% organic

Question 15

primary dentin

Answer 15

dentin thats made by odontoblasts when the tooth was developing, formed rapidly

Question 16

secondary dentin

Answer 16

process slows down, slightly more irregular shape

Question 17

aging dentin

Answer 17

=physiologic secondary dentin, thicker dentin is older

Question 18

reparative dentin

Answer 18

= made in response to some kind of trauma
control center wants protection from insult so they trigger dentin protection
extreme trauma can trigger all odontoblasts to fire and almost eliminate pulp chamber, can cause pulp necrosis (black tooth)

Question 19

sclerotic dentin

Answer 19

= sometime peritubular dentin increases and closes tubules

Question 20

DEJ

Answer 20

goal is to find adhesive that is as good as a the bond at the DEJ

Question 21

pulp dentin complex

Answer 21

one functional unit; does not have extra room to swell
arterioles/venules enter/leave through small foramina, no collateral circulation to help out
soft tissue, highly vascularized

Question 22

Purpose of pulp?

Answer 22

allows PT to know when something hurts

Question 23

pulp histology

Answer 23

depends on state of tooth, age of patient
Generally: very vascular (some lymphatics)
-collagen & ground substance
-formative cells (odontoblasts, fibroblasts
defense cells
sensory innervation
motor innervation

Question 24

sensory innervation of the pulp

Answer 24

C fibers - respond to inflammation
A alpha and delta fibers respond to fluid movement in tubules - triggered send sharp quick pain
only detect pain!

Question 25

zone of weil

Answer 25

cell free zone which is rich in both capillaries and nerve networks

Question 26

cementum

Answer 26

covers CLINICAL root
acellular (mostly fibers)
cellular (apical third)