Linings/Bases

Question 1

Phosphoric acid cements commonly in what form?

Answer 1

powder to liquid

Question 2

powder phosphoric acids?

Answer 2

zinc oxide with other metallic oxides

Question 3

liquid phosphoric acid is?

Answer 3

aqueous solution of phosphoric acid (50-60%)

buffers of AlPO4 and Zn3(PO4)2

Question 4

where does the setting reaction occur for phosphoric acid cements?
what kind of reaction

Answer 4

at the powder surface

rapid and exothermic

Question 5

how to mix the powder and liquid of phosphoric acid cement?

Answer 5

add powder incremently into the liquid = delays set and increases working time
use cool glass slab

Question 6

always replacing the cap lid prevents what?

Answer 6

crystallisation

Question 7

how long does PA cements take to harden?

Answer 7

4-7 minutes

Question 8

irritability properties of PA cements?

Answer 8

low pH
low MW
= high irritancy

Question 9

properties of PA cements?

Answer 9

insulator
can withstand condensing
radiopaque

Question 10

PA cements not good for?

Answer 10

compatibility
obtundant
not adhesive/no coronal seal

Question 11

variants of PA cement components?

Answer 11

silicophosphate cement = powder and liquid
aqueous phosphoric acid and buffers
zinc oxide and aluminasilicate glass

Question 12

properties of silicophosphate cements?

Answer 12

increased strength
fluoride
less soluble

Question 13

copper cement variant of PA cement?

Answer 13

aqueous phosphoric acid and buffers
powder is zinc oxide, black copper cement
black in colour
bacteriocidal

Question 14

how to zinc oxide eugenol cements come?

Answer 14

powder and liquid or 2 pastes

Question 15

liquid part of zinc eugenol cement?

Answer 15

eugenol with olive oil to control viscosity

Question 16

powder part of zinc eugenol cement?

Answer 16

zinc oxide with hydorgenated resin/polystyrene for reinforcement

Question 17

accelerator in zinc oxide?

Answer 17

zinc acetate creates iconic medium to faster set

Question 18

how do ZnO eugenols set?

Answer 18

set by chelation

continuous in cavity as moisture present

Question 19

zno eugenol beneficial in what way?
bacteriocidal because of?
insulator?

Answer 19

has a beneficial irritancy
zinc
yes

Question 20

zno eugenol :
can withstand if?
radiopaque because?
obtundant?

Answer 20

resin reinforced
zinc
yes

Question 21

disadvantages of zno eugenol?

Answer 21

not adhesive = no coronal seal

not compatible with resin composites

Question 22

deriviatve of zno eugenol?

Answer 22

ortho ethoxy benzoic acid
powder - zno 60%, quartz 35%
liquid - ortho ethoxy benzoic acid eugenol
stronger than zinc oxide eugenol

Question 23

calcium hydroxide is?

Answer 23

a suspension of calcium hydroxide in water - dries easily

fractured friable film

Question 24

instead of water use?

Answer 24

1) methylo cellulose in water
2) synthetic polymer in volatile solvent
both still weak

Question 25

modern caoh activated how?

Answer 25

chemically

VLC activated

Question 26

paste 1?

paste 2?

Answer 26

1 - glycol salicylate e.g butylere glycol disalicylate

2 - zinc oxide with calcium hydrozie

Question 27

on reacting of pastes what is formed?

Answer 27

reacting chelate compounds maily form zinc

Question 28

how is caoh light activated?

Answer 28

vlc activated polymerisation of a mma

or monomer mixed with HEMA = absorbs water to liberate hydroxyl from caoh

Question 29

calcium hydroxide moisture increases?

Answer 29

rate of set

Question 30

the vlc reaction with calcium hydroxide is ?

Answer 30

exothermic

Question 31

high ph of caoh gives?

Answer 31

beneficial irritancy

Question 32

high ph of caoh renders it what?

Answer 32

bacteriocidal

Question 33

other properties of caoh?

Answer 33

insulator
radiopaque
good restorative