Flashcards in priciples of adhesion, acid etch and bonding agents Deck (32):
how has adhesive material aided preventative and restorative dentistry?
seals vulnerable pits and fissures
allows conservation of tooth tissue
three approached to achieving attachment to tooth
chemical adhesion to enamel/ dentine
what is an example of micromechanical?
what is etching?
introducing pits and imperfections to allow resin to flow into these
what is chemical adhesion?
coupling agents bond to material and tooth (poly acids)
what is an example of chemical adhesion?
what is complex?
wetting, penetration and formation of bound material and restorative substrate interface
how can good wetting be determined?
small angle... low wetting
large angle- high wetting
who introduce acid etch for enamel margins?
what is the bond strength re acid etching?
how does acid etch work?
increased surface roughness
increases enamel surface energy
how does etch increase enamel surface energy?
removes surface contaminants
facilitates micro mechanical retention
what factors effect etching?
time 10-60 seconds
washing- 60 seconds
what is the purpose of drying?
enables hydrophobic rein to penetrate and attach
what happens if etched for too long?
precipitation of calcium and phosphate
what properties does the ideal dental adhesive have?
high bond strength
immediate and durable bond
prevent bacterial ingress
what problems re. dentine bonding?
dentine is hydrophilic
consist of inorganic and organic material
covered by smear layer
what is a primer?
alters surface appearance and removes smear layer
what is the function of coupling agent?
component that does the sticking
what does the sealer do?
flows into dentinal tubules
seals dentine with surface layer rich in methacrylate
ensures bonding to resin
what are dentine conditioners?
what is the reaction re etch and priming?
acid based reaction with hydroxyapatite- opens dentinal tubules
what depth of deminerlisation?
up to 4 micron
what do primers do?
bond hydrophobic composites to hydrophilic dentine
act as adhesive
what is the general formula for primers?
methacrylate group in resin matrix
pacer that allows resin to move
component that interacts with dentine
what is a popular primer?
what are the negative effects of HEMA?
What are sealers?
BISGMA & HEMA