Principles of Adhesion Flashcards
(29 cards)
what do adhesive materials offer potential to
seal vulnerable pits and fissures
conserve tooth tissue
reduce/elim micro leakage
what are the 3 methods of achieving adhesion
micro mechanical
hem adhesion to enamel/dentine
complex (west, pen and bond)
what are a means of micro mechanical attachments
acid etch
apply resins
what are the means of chemical adhesion to enamel/dentine
coupling agents/cements contain polyacids
what is a means of ‘couplex’ attachment
modern dentine bonding agents
attraction between adhesive and adherend lowers what
surface tension of adhesive so will flow into irregularities
what is the use of acid etch essential
applying acid gel
what does acid etch do
selective decalcification of enamel prisms
micromech tags which bonding resin may flow
20-25 MPa
what does acid etch do to the surface
increases roughness
increase enamel surface energy
what does an increaein enamel energy do
remove surface contaminate
good wetting
facilitates micro mechanical tetention
what are factors affecting acid etch
etching time
washing
drying
what does etching tim eeffect
enough to work
not too long as allows prep of calcium nd phosphate
what does waking and drying do to acid etch
wash - approx 60s to remove debris
dry - enable hydrophobic resin to penetrate and attach
what is adhesion to dentine like
evolving
stick to same manu
what are the properties of the ideal dental adhesive
high bond strength to enamel and dentine immediate and durable bon reliable bond prevent bac ingress be safe to use be simple to use
what are the problems associated with boding to dentine
hydrophilic
vital tissue
inorganic and organic material
covers by smear layer
what does cavity prep result in
a smear layer that occludes tubules
what are primers
dentine conditioners
acids
alter surface appearance and characteristics of dentine
what are coupling agents
primers
components that do sticking
what are sealers
flow into dentinal tubules
seal dentine with surface layer rich in methacrylate
ensures bonding to resin
what are some examples of primers (dentine conditioners)
malice
oxalic
phosphoric
nitric acids
what essentially happens with a primer (dentine conditioner)
acid base reaction with hydroxyapatite
open dentinal tubules
demineralise surface dentine to depth 4 microns
what essentially happens with coupling agents (Primers)
act a adhesive
bond to hydrophobic composites to hydrophilic dentine
formula - MRX dissolved in volatile solvent
HEMA popular
is there time dept degeneration
acid open tubules risk nano leakage
- dentine etch greater than resin can penetrate
- dentine microstructure disruption and fail
