Linings & Bases

Question 1

give some of the uses of dental cements

Answer 1

• temporary restorations
• cavity linings to protect pulp
• sedation/insulation of pulp
• cementing fixed prosthetics

Question 2

give 1 ideal property of dental cements

Answer 2

non-irritant

Question 3

explain the acid-base reaction of dental cements

Answer 3

many cements are acidic based and so an irritant to the pulp but on setting there is a rapid increase of pH –> not irritant anymore :)

Question 4

describe the reaction with phosphoric acid based cements

Answer 4

vigorous reaction
between certain basic oxides and phosphoric acid
form phosphate salts of low solubility
exothermic

Question 5

give 3 of the main phosphoric acid based cements

Answer 5

zinc phosphate, copper phosphate, silicophosphate

Question 6

how are phosphoric acid based cements usually presented?

Answer 6

P:L

Question 7

how is the setting time delayed and work time increased when using phosphoric acid based cements?

Answer 7

powder is introduced incrementally into liquid

Question 8

initial set time for phosphoric acid based cements?

Answer 8

4-7 mins

Question 9

give 2 examples of cements based on organometallic chelate compounds

Answer 9

zinc oxide eugenol cements

calcium hydroxide cements

Question 10

how are zinc oxide eugenol cements typically presented?

Answer 10

P:L or as 2 pastes

Question 11

how do zinc oxide eugenol cements set?

Answer 11

by chelation

Question 12

how are calcium hydroxide cements typically presented?

Answer 12

suspension of CaOH in water

Question 13

how do calcium hydroxide cements set?

Answer 13

VLC activation

Question 14

once applied to the cavity base, what happens in the calcium hyrdoxide cement?

Answer 14

dries to give a layer CaOH

Question 15

what are the 2 pastes of Calcium Hydroxide cements?

Answer 15

glycol sulphate and zinc oxide in CaOH

Question 16

what are the 2 main groups of lining and luting cements?

Answer 16

polycarboxylate cements

glass polyalkanoate cements

Question 17

how are polycarboxylate cements typically presented?

Answer 17

P:L

Question 18

why are polycarboxylate cements not widely used for restorative linings?

Answer 18

difficult to handle as very rubbery

Question 19

what are polycarboxylate cements widely used for?

Answer 19

as luting cements

Question 20

Give a commercial name for a RMGIC used for restorative linings

Answer 20

vitrebond

Question 21

what is the difference in composition between glass ionomer(polyalkanoate) for lining and luting compared to that for restorations?

Answer 21

the glass particles are smaller for lining and luting

Question 22

why are the glass particles in GI smaller for lining and luting?

Answer 22

to allow the formation of a thinner film thickness for luting

Question 23

how is GI for lining and luting typically presented?

Answer 23

P:L

Question 24

is GI for lining and luting stronger than that of polycarboxylates?

Answer 24

yes

Question 25

what must be done after lining and luting with GI and where does this become difficult?

Answer 25

varnish must be applied, difficult if the GI is subgingival