Day 1 Lecture 2

Question 1

Periodontium

Answer 1

Gums and jaw

Question 2

TMJ

Answer 2

Temperomandibular joint

Question 3

Restorative + Prosthetic Dentistry

Answer 3

Repair and replace teeth

Question 4

Baby teeth

Answer 4

Deciduous - 20

Question 5

Incisors

Answer 5

Cut/shear food, phonetics function and aesthetics

Question 6

Canines

Answer 6

Shear, tear, pierce food, longest roots and strategic position in arch, key to occlusion (protection) - allow lateral guidance

Question 7

Premolars

Answer 7

Grinding, fine chewing

Question 8

Molars

Answer 8

Multi-rooted, strong, grinding, crushing, chewing.

Question 9

Clinical Crown

Answer 9

What you can see

Question 10

Anatomical crown

Answer 10

where DEJ is and on

Question 11

DEJ

Answer 11

dentin enamal juncture

Question 12

Dentin strength

Answer 12

1/10 strength - second hardest bone in body

Question 13

Enamel comp.

Answer 13

90-95% inorganic HA, 4-8% H20, 1-2% protein

Question 14

HA

Answer 14

hydroxyapatite -a calcium phosphate

Question 15

Enamel structure

Answer 15

striated - rods from ameloblasts

Question 16

Ameloblasts

Answer 16

form enamel from DEJ, extinct after deposition. Epithelial origin

Question 17

Dentin/pulp complex

Answer 17

Mesenchymal in origin, odontoblasts in pulp

Question 18

Odontoblasts

Answer 18

Form dentin, still can make dentin throughout life - cell bodies line wall of pulp chamber

Question 19

Enamel organization

Answer 19

teardrops, rods are 4-8 microns, rods surrounded by organic sheath (easily sheared). Head region and tail region are 5 microns wide/long respectively

Question 20

Enamel crystals with fluoride

Answer 20

Fluorapatite

Question 21

Crystalite direction in/around rods

Answer 21

parallel in rods, up to 65deg fro prism direction in periphery/tail

Question 22

Gnarled enamel

Answer 22

Occurs at cervical (visible base) and incisal/occlusal (pointed, valley) areas

Question 23

Enamel properties

Answer 23

Hard brittle parallel to rod direction, rarely follows straight path. Low tensile strength perpendicular to rod direction (dentin is stronger in terms of tensile)

Question 24

Enamel fracture lines

Answer 24

interprismatic - don’t go into dentin. dentin acts as a cushion and the tooth doesn’t shatter as a result

Question 25

Isotropic

Answer 25

same in all directions

Question 26

Anisotropic

Answer 26

depends on direction (tooth)

Question 27

When is enamel subject to fracture

Answer 27

When unsupported by dentin

Question 28

Dentin comp.

Answer 28

50% vol HA (75% wt), 25% vol collagen (20% wt), 25% vol H20 (5%wt)

Question 29

Dentin tubules

Answer 29

extend from pulp chamber to DEJ. Related to cells that line pulpal wall

Question 30

Peritubular dentin

Answer 30

denser, has had a longer time to deposit (larger and near DEJ)

Question 31

Intertubular dentin

Answer 31

located between tubules, hasnt had much time to deposit

Question 32

Dentin tubules

Answer 32

channel for odontoblastic process, allows fluid movement and ion transport. Allows remineralization, apposition of p. dentin, pain perception (perceived by nerves in pulp)

Question 33

Odontoblastic process

Answer 33

extension of odontoblast into dentin - cytoplasmic, aka tomes fibers

Question 34

Dentin structure

Answer 34

not uniformly mineralized (peritubular more than intertubular), principle organic component = collagen (toughness). HA crystals in collagen (smaller than enamel). 20% less hard than enamel, higher tensile strength, lower stiffness (more elastic). *isotropic*, cushion

Question 35

Predentin

Answer 35

Unmineralized zone of dentin immediately adjacent to cell bodies of odontoblasts

Question 36

Primary dentin

Answer 36

First dentin formed - forms up to 3 years after eruption

Question 37

Secondary dentin

Answer 37

Without any obvious stimulus, dentin direction changes and deposition slows.

Question 38

Reparative dentin (tertiary)

Answer 38

pulp fills in cavity in case of injury.

Question 39

Sclerotic dentin

Answer 39

Doesnt follow rules, like gnarled enamel, especially down in cervical area

Question 40

Dentin differ from Enamel

Answer 40

Less mineral content, small tubules for fluid (pain reception) and ion transport. Ability to repair or regenerate to physical or chemical response until pulp dies.

Question 41

Radiopaque

Answer 41

White on x-ray (enamel)

Question 42

Cementum

Answer 42

Periodontum - borders tooth. Slightly ligher in color than dentin. Lost as periodontium is lost (rarely seen in clinic, often brushed away).

Question 43

Periodontal Ligament - hold

Answer 43

Sharpeys fibers holds

Question 44

Cementum composition

Answer 44

5-10% mineral content. 45-50% inorganic (HA) by weight, 50-55% organic matter and water by weight (mainly collagen and protein polysaccharides). highest fluoride content of all mineralized tissue.

Question 45

Cementum structure

Answer 45

hard, avascular on anatomic roots. Formed continually throughout life, repair is limited as it is based on surrounding tissue (once it's gone it is gone). Slightly softer than dentin, but permeable.

Question 46

Cementum origin

Answer 46

Formed by cementoblasts which develop from mesenchymal cells in connective tissue of dental follicle.

Question 47

Cementodentinal Junction (CDJ)

Answer 47

Attachment of cementum to dentin

Question 48

Cementoenamel Junction (CEJ)

Answer 48

Cervical line, where cementum joins enamel

Question 49

Dental Pulp functions

Answer 49

Formative/developmental, Nutritive, Sensory/Protective, Defensive/reparative

Question 50

Formative/developmental (pulp)

Answer 50

Production of primary and secondary dentin by odontoblasts

Question 51

Nutritive (pulp)

Answer 51

Supplies moisture and nutrients through blood to odontoblasts and their processes

Question 52

Sensory/Protective (pulp)

Answer 52

Provides nerve fibers to mediate pain (only response).

Question 53

Defensive/reparative (pulp)

Answer 53

Deposition of reparative dentin in response to stimuli. Inflammatory reaction to severe irritation - this can cause pulp death.