cavity bases and liners

Question 1

what are intermediate restorative materisals

Answer 1

materials applied to dentine to protect the pulp prior to placing the main restorative material

Question 2

types of itermediate restorative materials

Answer 2

varnish
cavity liner
cavity base

Question 3

varnihs

Answer 3

thin polymer seal to the dentine surface

Question 4

cavity liner

Answer 4

layer of protective dentine sealer less than 0.5mm thick

Question 5

cavity bas

Answer 5

dentine replacement intend to eliminate undercuts or minimise bulk of main restorative materail
thicker than 0.5mm

Question 6

clinical need of IRMs

Answer 6

dental pulp chamber sensitive
may need additional protection for the pulp when placing direct restorative material
prevents heat or chemical diffusion to pilp

Question 7

what might adversely affect the pulp

Answer 7

physical stimuli e.g. temp or mechanical forces
chemical stimuli e.g. acids
which may relate to
caries, microbial ingress or contamination

Question 8

n

Answer 8

n

Question 9

an ideal cavity base or liner properties

Answer 9

1) safe and biocompatible
2) form effective dentine seal against chemicals, bacteria and other stimuli
3) may encourage dentine generation in pulp chamber (reparative dentine, 2 or 3)
4) chemically and mechanically compatible with other restorative materials
5) tooth coloured, radiopaque and easy to place

Question 10

dental materials used as IRMs

Answer 10

1) Varnishes (polymer solution in solvent)
2) calcium hydroxide cemenets (dycal)*
3) MTA (biotentine)*
4) Zinc oxide cements commonly zinc oxide-eugenol or ZOE
5) Glass ionomer cements
6) Resin modified glass ionomer cements
7) visible light cured resins
* used where pulp exposed

Question 11

cavity varnishes material and how it works

Answer 11

natural or synthetic polymer resins dissolved in solvent and applied to cavity floor with brush of cotton
solvent evaporates to leave a thin layer of resin
acts as a barrier against chemical penetration of tooth tissue and may protect against micro leakage and secondary caries

Question 12

calcium hydroxide cements

Answer 12

rigid self setting material

presented as two pastes for mixing

Question 13

two paste material used in calcium hydroxide cements

Answer 13

1) calcium hydroxide, zinc oxide
2) salicylate ester, titanium oxide, calcium sulphate
chemical reaction forms zinc and calcium dislylate and other compounds

Question 14

properties of calcium hydroxide

Answer 14

• Alkaline nature due to free Ca(OH)2 may promote tertiary dentine formation (due to slight irritation) and provide antibacterial properties (may help heal cavity)
• low compressive strength but sufficient to withstand condensation of amalgam
• initial pH greater than 11, alkalinity associated with local tissue irritation that later mineralise (reparative dentine once dentine like in appearance)
• may be used as a protective base or liner under primary restorative, acts primarily as a pulp camp
• slowly soluble in water

Question 15

what is the leading brand of CaOH cement in Uk

Answer 15

dycal

radiopaque and ivory colour

Question 16

how is zinc oxide eugenol formed

Answer 16

acid base reaction between a metal oxide and eugenol (forms metal eugenolate chelate)

Question 17

what zinc oxide eugenol used for most commonly

Answer 17

tempoarary restoration

can be used for base/liner

Question 18

why is zinc oxide eugenol unpopular

Answer 18

due to risk of pulpal necrosis and inhibition of composite rein polymerisation( stops setting reaction)

Question 19

why should zinc oxide eugenol not be used with compostie

Answer 19

due to inhibition of composite resin polymerisation

Question 20

what is IRM

Answer 20

zinc oxide eugenol material

Question 21

what is IRM designed fro

Answer 21

to remain in place for 12 montths

uses underneath a non resin restoraion

Question 22

glass ionomer cements properties

Answer 22

• Relatively robust (compressive strength >50 Mpa)
• adhesive
• insoluble
• insulating
• fluoride releasing
• aesthetic (can be used as a direct restorative material)

Question 23

what is glass ionomer cements composed of

Answer 23

basic fluoaluminsilicate glass
polymermic acid
water
tartaric acid

Question 24

how is GIC formed

Answer 24

mixing via acid base reaction

- metal cations form salt bridges with ionised carboxylate acid groups on high molecular weight polyacids

Question 25

Why is GIC popular

Answer 25

predictable adhesive bond

good marginal seal

Question 26

Resin modified glass ionomer cement vs GIC

Answer 26

similar but addition of
HEMA- water miscible monomer
photoinitiator

Question 27

how does resin modified GIC set

Answer 27

acid base reaction and photo polymerisation (HEMA polymerises)
shares GIC chemical bond to untreated dentine

Question 28

future trend materiasl

Answer 28

mineral trioxide aggreagate

diodentine

Question 29

mineral trioxide aggregate

Answer 29

can be used for pulp capping, base or liner
sets slowly
good at stimulating reparative dentien

Question 30

diodentine

Answer 30

calcium silicate

sets in one hour

Question 31

sealing dentine leads to

Answer 31

reduced microleakage

less post op sensitivity with reduced risk of plural inflammation

Question 32

thermal insulation

Answer 32

less sensitivity to hot or cold

Question 33

mechanical protection

Answer 33

resistant to packing or elimination of undercuts

better supported restoration and further pupla protection

Question 34

what is a key driver of the use of dycal i.e. CaOH

Answer 34

stimuli of reparative dentine

Question 35

what is the best protection for pulp tissues

Answer 35

healthy dentine