Luting Agents

Question 1

what are the properties of a luting agent

Answer 1

viscosity and film thickness
easy of use
radiopaque
marginal seal
aesthetics
solubility
cariostatic
biocompatible
mechanical properties

Question 2

what is viscosity and film thickness dependent on

Answer 2

size of powder or filler particles in material

Question 3

what does the viscosity need to be to allow seating of restoration

Answer 3

low

Question 4

what should the film thickness be

Answer 4

25um or less

Question 5

ideally, what should the marginal seal be

Answer 5

the luting agent should bond chemically to the tooth and indirect restoration with a permanent and impenetrable bond

Question 6

why is it important for a luting agent to be cariostatic

Answer 6

prevent secondary caries around crown margins

Question 7

what are the mechanical properties of a luting agent

Answer 7

high compressive strength
high tensile strength
high hardness
youngs modulus similar to tooth

Question 8

what are the main types of material used as luting agents

Answer 8

dental cement
glass ionomer cement
composite resin luting agents

Question 9

what is the main type of dental cement

Answer 9

zinc phosphate

Question 10

what is zinc phosphate made of

Answer 10

powder and liquid

Question 11

what is the reaction of zinc phosphate

Answer 11

acid base
then hydration reaction producing crystalised phosphate matrix

Question 12

what does aluminium oxide in zinc phosphate do

Answer 12

prevent crystallisation leading to an amorphous glassy matrix

Question 13

what are the problems with zinc phosphate

Answer 13

low pH
exothermic setting reaction
not adhesive to tooth or restoration
not cariostatic
brittle
opaque

Question 14

what is the difference between zinc phosphate and zinc polycarboxylate cement

Answer 14

phosphoric acid is replaced by polyacrylic acid
can bond to tooth
less heat reaction
pH returns to normal quicker

Question 15

what are the problems with zinc polycarboxylate cement

Answer 15

difficult to mix and manipulate
soluble in oral environment at lower pH
opaque
lower compressive strength

Question 16

what is the difference between glass ionomer and glass ionomer cement

Answer 16

cement particle size is smaller allowing for suitable film thickness

Question 17

what is the setting reaction of glass ionomer cement

Answer 17

acid base
dissolution
gelation
hardening

Question 18

how does glass ionomer cement bond to the tooth

Answer 18

ion exchange with calcium in enamel and dentine
hydrogen bonding with collagen in dentine

Question 19

what are the advantages of glass ionomer cements

Answer 19

low shrinkage
long term stability
insoluble once fully set
aesthetically better than zinc phosphate
self adhesive to tooth substance
fluoride release
cheap

Question 20

what is the difference between RMGIC and RMGI

Answer 20

smaller particle size for film thickness

Question 21

what is the difference between RMGIC and GIC

Answer 21

addition of hydrophilic monomer HEMA

Question 22

what is the setting reaction of RMGIC

Answer 22

acid base
light activation for polymerisation of HEMA
REDOX reaction allowing dark curing

Question 23

what does the incorporation of resin allow for in RMGIC

Answer 23

shorter setting time
longer working time
higher compressive and tensile strengths
higher bond strength to tooth
decreased solubility

Question 24

what are the potential problems with RMGI

Answer 24

HEMA is cytotoxic
HEMA swells - cant be used with conventional porcelain crowns
no bond to indirect restoration

Question 25

what must composite luting agents be used with

Answer 25

DBA

Question 26

what bonding does composite luting agents experience

Answer 26

micromechanical bond to internal surface of inlay chemical bond to remaining c=c bonds on fitting surface of inlay

Question 27

why does porcelain need to be bonded to tooth

Answer 27

it is brittle and needs to prevent fracture

Question 28

what is required to make porcelain compatible with composite resin luting agents

Answer 28

etch and surface wetting agent

Question 29

what surface wetting agent is used on porcelain

Answer 29

silane coupling agent

Question 30

what does the silane coupling agent do to porcelain

Answer 30

bonds to oxide groups on porcelain surface and to composite resin luting agent

Question 31

how is a metal surface roughened

Answer 31

etch sandblasting

Question 32

what does sandblasting do to metal

Answer 32

roughen it but does not give undercut surface of etching

Question 33

what is used to bond to non-precious metal

Answer 33

materials with carboxylic and phosphoric acid derived resin monomers MDP and 4META

Question 34

what happens when bonding to non-precious metal

Answer 34

acidic end of molecule reacts with metal oxide and makes it hydrophobic

Question 35

what sort of material is needed when bonding to metal

Answer 35

dual curing material

Question 36

what is a self adhesive coupling agent

Answer 36

metal coupling agent incorporated into composite resin self curing material

Question 37

what types of restoration require GIC

Answer 37

MCC metal post zirconia crown gold restoration

Question 38

what is a temporary cement

Answer 38

cement which holds temporary restorations in place while permanent restoration fabricated

Question 39

how is a temporary cement removable

Answer 39

it contains a wax which makes it easier to remove can also add petroleum jelly in

Question 40

what are the 2 main types of temporary cement

Answer 40

with and without eugenol

Question 41

when would you not use a eugenol temporary cement and why

Answer 41

when the permanent cement is going to be a resin cement it can interfere with the setting reaction