Calcium Hydroxide and Zinc Oxide Based Materials for Liners

Question 1

what are the main constituents of setting calcium hydroxide liner?

Answer 1

base and catalyst

Question 2

what types of base are used in settling calcium hydroxide?

Answer 2

calcium hydroxide, zinc oxide, zinc stearate, N-ethyl toluene sulphonamide

Question 3

what types of catalyst are used in setting calcium hydroxide?

Answer 3

butylene glycol disalicylate, titanium dioxide, calcium sulphate, calcium tungstate

Question 4

what is the setting reaction for calcium hydroxide liner?

Answer 4

chelation reaction between the ZnO and the butylene glycol disalicylate

Question 5

what is the mode of action of CaOH liner?

Answer 5

bacteriocidal to cariogenic bacteria, causes irritation to odontoblast layer which drives reparative dentine formation

Question 6

what are the properties of CaOH?

Answer 6

quick setting time, radiopaque, easy to use BUT low compressive strength, unstable and soluble

Question 7

what are the zinc oxide based cements?

Answer 7

zinc phosphate, zinc polycarboxylate, zinc oxide eugenol (ZOE), resin modified ZOE, ethyoxybenzoic acid (EBA) ZOE

Question 8

what are the powder components of zinc phosphate cement?

Answer 8

zinc oxide, magnesium dioxide, other oxides (alumina and silica)

Question 9

what are the liquid components of zinc phosphate cement?

Answer 9

aqueous solution of phosphoric acid, oxides which buffer the solution

Question 10

what is the reaction of zinc phosphate cement?

Answer 10

acid base followed by a hydration reaction resulting in the formation of a crystalised phosphate matrix

Question 11

what are the problems with zinc phosphate cement?

Answer 11

low pH, exothermic setting reaction, not adhesive to tooth or restoration, not cariostatic, final set takes 24hrs, brittle, opaque

Question 12

what is the difference between zinc phosphate cement and zinc polycarboxylate cement?

Answer 12

the phosphoric acid is replaced by polyacrylic acid

Question 13

what is the advantage of zinc polycarboxylate cement?

Answer 13

it bonds to tooth surfaces in a similar way to glass ionomer cements, less heat of reaction, pH turns neutral quicker, cheap

Question 14

what are the problems with zinc polycarboxylate cement?

Answer 14

difficult to mix and manipulate, soluble in oral environment at lower pH, opaque, lower modulus and compressive strength than zinc phosphate

Question 15

what are zinc oxide eugenol cements (ZOE) used for?

Answer 15

linings/base in deep cavities, temporary restorations, root canal sealer, periodontal dressings

Question 16

what reaction does ZOE cement have?

Answer 16

acid base

Question 17

what is the acid and base in ZOE cement?

Answer 17

base = ZnO and acid = eugenol

Question 18

what is the setting reaction of ZOE?

Answer 18

chelation reaction of zinc oxide with the eugenol to form zinc eugenolate matrix

Question 19

what are the properties of ZOE?

Answer 19

adequate working time, relatively rapid setting time, low thermal conductivity, low strength around 20MPa, radiopaque, high solubility

Question 20

when should ZOE materials not be used?

Answer 20

under composite resin materials

Question 21

what is resin modified ZOE?

Answer 21

resin added to the powder and liquid of ZOE

Question 22

what is the impact of resin on resin modified ZOE?

Answer 22

give a stronger backbone to the set material, increases the compressive strength to >40MPa, greatly decreases solubility

Question 23

what is the difference between EBA ZOE and normal ZOE?

Answer 23

ethyoxybenzoic acid is used in the liquid for EBA ZOE

Question 24

what are the properties of EBA ZOE?

Answer 24

greater strength to set material, stronger than ZOE or resin modified ZOE, less soluble