7-Tooth Histology

Question 1

Enamel

Answer 1

Acellular
avascular
non-innervated
non-dynamic
de/remineralization on the surface

Question 2

Which parts of teeth change?

Answer 2

Dentin, pulp and peridontum change

while enamel wears down

Question 3

Is enamel thickness even?

Answer 3

No it varies along its surface

Question 4

Enamel composition (general)

Answer 4

90-92% inorganic
1-2% organic
4-6% water

Question 5

Major structural part of the enamel

Answer 5

enamel rod

Question 6

How many enamel rods per tooth?

Answer 6

5-12 million

Question 7

Enamel rod shape

Answer 7

Waavy and diameter gets 2-3x larger as it goes drom DEJ to tooth surface
and is slightly tall on one end(cross-sectionally)
They don’t have interruptions or branches

Question 8

Space between the rods

Answer 8

Inter-rod substance aka rod sheath

Question 9

Rod sheath composition

Answer 9

Water and trace proteins

Question 10

what are the rods made of

Answer 10

Apatite crystals

Question 11

At what angle do enamel rods meet the tooth surface and DEJ?

Answer 11

90˚

Question 12

Amelogenesis

Answer 12

Formation of enamel

Question 13

Where does amelogenesis start and when does it end?

Answer 13

Starts at DEJ and ends before tooth eruption

Question 14

Dentinogenesis

Answer 14

Formation of dentin

Question 15

Can enamel repair itself?

Answer 15

NOOOOO

Question 16

Dentin function

Answer 16

Resilient support for enamel(like wood under glass) and restorations
-Most of the tooth structure

Question 17

Dentin properties

Answer 17

Sensitive & conducttive
Very porous
very dynamic
pulp’s partner

Question 18

Is enamel permeable?

Answer 18

Yes which is what causes stains and allow for whitening

Question 19

Dentin structures

Answer 19

Dentinal tubules
Peritubular dentin
Intertubular dentin

Question 20

Dentinal tubules structure

Answer 20

Can branch and communicate with other tubules

Gets smaller in diameter going from pulp to DEJ

Question 21

Peritubular dentin vs intertubular dentin

Answer 21

Peritubular is more mineralized.

Forms outline for dentinal tubules

Question 22

intertubular dentin composition

Answer 22

• Type I collagen
• Small hydroxyapatite crystals
• Water

Question 23

What is in dentinal tubules

Answer 23

Water/dentinal fluid and cellular process of the odontoblasts

Question 24

What is the odontoblast process called?

Answer 24

Tomes fiber

Question 25

dentin chemistry

Answer 25

Heterogenous 50% inorganic(apatite crystals) 5-25% water 5-25% organic(collagen)

Question 26

Primary dentin

Answer 26

Dentin made before eruption

Question 27

Secondary dentin

Answer 27

Dentin is still made after eruption but slows down and is more irregular

Question 28

Physiological secondary dentin

Answer 28

This is made slowly and continuosly with age

Question 29

Reparaitive dentin

Answer 29

secondary dentin caused by trauma. Made in dentin and the peritubular dentin

Question 30

Sclerotic dentin

Answer 30

When peritubular dentin gets thicker and close off.

Question 31

Dentin response to insult

Answer 31

- Dentin is injured(reversible?) - tubules sclerose - reparative dentinogenesis - pulpal inflammation - pulp recovery or necrosis

Question 32

Pulp properties

Answer 32

Arterioles and venules enter/leave via small foramina no collateral circulation no space for expansion collagen and ground substance defense and formative cells sensory and motor(for vasodilation) innervation

Question 33

Nerves in pullp

Answer 33

C, A-alpha, and A-delta fibers | -Pain only

Question 34

C-fibers

Answer 34

Dull throbby pain | respond to inflammation

Question 35

A-fibers

Answer 35

Respond to quick sharp pain | on the walls by the dentin and odontoblasts

Question 36

Zone of Weil

Answer 36

Right under the odontoblast layer

Question 37

Cementum

Answer 37

``` Covers clinical root -Acellular mostly fibers cellular(apical third) -hardness like bone -thickness varies -attached PDL to tooth ```

Question 38

Supportive hard tissues

Answer 38

- Cenemtum - Principle fibers - Sharpey's fibers - periodontal ligament - alveolar bone - cortical bone - cancellous bone