lecture 5

Question 1

3 types of impression material

Answer 1

rigid
plastic
elastic

Question 2

impression material

Answer 2

used to make negative molds of teeth

transfer to gypsum model

Question 3

two types of rigid impression material

Answer 3

ZOE

plaster

Question 4

two types of plastic impression material

Answer 4

wax

compound

Question 5

two types of elastic impression material

Answer 5

hydrocolloids

elastomers

Question 6

what is irreversible hydrocolloid

Answer 6

alginate (water base)

Question 7

viscoelastic

Answer 7

hydrocolloid or elastomers
hydrophobic synthetic impression material
polysulfides, siloxane, polyethers

Question 8

Gypsum products

Answer 8

dental plaster or stone

Question 9

ideal properties of gypsum products

Answer 9

cheap
long shelf life
pleasant to patient
good handling properties
biocompatibility

Question 10

alginates

Answer 10

-water based impression material
-calcium crosslinked
used as impression material for removable partial dentures, complete dentures, orthodontic models, and study models
NOT use for crown and bridge because not enough detail

Question 11

alginates are soluble in what and form what

Answer 11

water, form “sol”- resembles a solution but made up of colloidal particles dispersed in a liquid

Question 12

calcium cross link of alginates

Answer 12

ties two chains together. network of polymer chains

Question 13

setting reaction of alginate

Answer 13

sol –> gel formation
temperature controlled (reversable)
chemically controlled (irreversible)
cured by mixing water with powder. Disolve Ca ions that cross link alginate molecules

Question 14

dimensional stability

Answer 14

water loss and gain, cuz its water based undergoes shrinkage or expansion

Question 15

syneris

Answer 15

loss of water to surrounding

Question 16

imbibition

Answer 16

pickup of water

Question 17

polysiloxanes

Answer 17

inherently hydrophobic. but addition types can be make hydrophilic.
condensation type was first introduced
dimensional stable

Question 18

addition can be made hydrophilic by

Answer 18

adding surfactant

or chemical incorporation of hydrophilic moieties into silicone backbone

Question 19

cross linked by what1

Answer 19

hydrosilation reaction

Question 20

polysiloxanes are ______ stable than alginates or polysulfides

Answer 20

more

Question 21

role of surfactants

Answer 21

used to improve detail registration and detail transfer for polysiloxanes, make more hydrophilic

Question 22

polyethers

Answer 22

hydrophobic, but not as hydrophobic as polysiloxanes
Bad taste
good dimensionally stability

Question 23

gypsum

Answer 23

dehydrate form of calcium sulfate found in compact mass in nature

Question 24

calincation

Answer 24

dental gypsum products are manufactured by driving off part of the water of calcium sulfate dehydrate
(reversible reaction)

Question 25

reverse reaction of this calincation

Answer 25

when calcium sulfate hemihydrate (dental plaster, stone) is added to water. hemihydrate is covered back to dehydrate (exothermic rxn)

Question 26

dental stone or plaster used for models>

Answer 26

dental stone

Question 27

dental stone

Answer 27

dense, regularly shape, relatively nonporous cuboidal crystal material. Requires less water, aprox. 2.5 times stronger than plaster. used to make molds and casts

Question 28

denture base need to last a _____ time so they have what and what

Answer 28

long time, have fillers and dimethylcrylates that cross link material.

Question 29

denture base is normally _____ _____ cured

Answer 29

visible light

Question 30

provisional materials

Answer 30

temporary and need to be removed, chemically cured. (achieved by mixing). example Trim and Jet

Question 31

example of denture base

Answer 31

TRIAD, custom tray material

Question 32

mouth guard material

Answer 32

thermoplastic

Question 33

thermoplastic polymer

Answer 33

has a low softening point
thermally processed with hot water
vaccumed form

Question 34

what controls the properties of mouthguard

Answer 34

copolymers- design to absorb impact

high toughness, low ridigity.