Luting Agents Flashcards
what are the properties of a luting agent
viscosity and film thickness
easy of use
radiopaque
marginal seal
aesthetics
solubility
cariostatic
biocompatible
mechanical properties
what is viscosity and film thickness dependent on
size of powder or filler particles in material
what does the viscosity need to be to allow seating of restoration
low
what should the film thickness be
25um or less
ideally, what should the marginal seal be
the luting agent should bond chemically to the tooth and indirect restoration with a permanent and impenetrable bond
why is it important for a luting agent to be cariostatic
prevent secondary caries around crown margins
what are the mechanical properties of a luting agent
high compressive strength
high tensile strength
high hardness
youngs modulus similar to tooth
what are the main types of material used as luting agents
dental cement
glass ionomer cement
composite resin luting agents
what is the main type of dental cement
zinc phosphate
what is zinc phosphate made of
powder and liquid
what is the reaction of zinc phosphate
acid base
then hydration reaction producing crystalised phosphate matrix
what does aluminium oxide in zinc phosphate do
prevent crystallisation leading to an amorphous glassy matrix
what are the problems with zinc phosphate
low pH
exothermic setting reaction
not adhesive to tooth or restoration
not cariostatic
brittle
opaque
what is the difference between zinc phosphate and zinc polycarboxylate cement
phosphoric acid is replaced by polyacrylic acid
can bond to tooth
less heat reaction
pH returns to normal quicker
what are the problems with zinc polycarboxylate cement
difficult to mix and manipulate
soluble in oral environment at lower pH
opaque
lower compressive strength
what is the difference between glass ionomer and glass ionomer cement
cement particle size is smaller allowing for suitable film thickness
what is the setting reaction of glass ionomer cement
acid base
dissolution
gelation
hardening
how does glass ionomer cement bond to the tooth
ion exchange with calcium in enamel and dentine
hydrogen bonding with collagen in dentine
what are the advantages of glass ionomer cements
low shrinkage
long term stability
insoluble once fully set
aesthetically better than zinc phosphate
self adhesive to tooth substance
fluoride release
cheap
what is the difference between RMGIC and RMGI
smaller particle size for film thickness
what is the difference between RMGIC and GIC
addition of hydrophilic monomer HEMA
what is the setting reaction of RMGIC
acid base
light activation for polymerisation of HEMA
REDOX reaction allowing dark curing
what does the incorporation of resin allow for in RMGIC
shorter setting time
longer working time
higher compressive and tensile strengths
higher bond strength to tooth
decreased solubility
what are the potential problems with RMGI
HEMA is cytotoxic
HEMA swells - cant be used with conventional porcelain crowns
no bond to indirect restoration
what must composite luting agents be used with
DBA
what bonding does composite luting agents experience
micromechanical bond to internal surface of inlay
chemical bond to remaining c=c bonds on fitting surface of inlay
why does porcelain need to be bonded to tooth
it is brittle and needs to prevent fracture
what is required to make porcelain compatible with composite resin luting agents
etch and surface wetting agent
what surface wetting agent is used on porcelain
silane coupling agent
what does the silane coupling agent do to porcelain
bonds to oxide groups on porcelain surface and to composite resin luting agent
how is a metal surface roughened
etch
sandblasting
what does sandblasting do to metal
roughen it but does not give undercut surface of etching
what is used to bond to non-precious metal
materials with carboxylic and phosphoric acid derived resin monomers
MDP and 4META
what happens when bonding to non-precious metal
acidic end of molecule reacts with metal oxide and makes it hydrophobic
what sort of material is needed when bonding to metal
dual curing material
what is a self adhesive coupling agent
metal coupling agent incorporated into composite resin
self curing material
what types of restoration require GIC
MCC
metal post
zirconia crown
gold restoration
what is a temporary cement
cement which holds temporary restorations in place while permanent restoration fabricated
how is a temporary cement removable
it contains a wax which makes it easier to remove
can also add petroleum jelly in
what are the 2 main types of temporary cement
with and without eugenol
when would you not use a eugenol temporary cement and why
when the permanent cement is going to be a resin cement
it can interfere with the setting reaction
