Resin Based Composite Materials - curing Flashcards
How can resin composites be categorised by means of setting mechanism?
chemically cures
light cured
dual cured = light + chemically
What is the reaction in both chemical and light curing materials?
free radical polymerisation reaction
How is the chemically cured resin system supplied?
two-paste system
What is a two-paste system?
setting reaction commences when the two pastes are blended
What 2 chemicals are involved in a chemically cured resin composite?
tertiary amine with a benzoyl peroxide
What effects the light cured resin composites?
photo-initiator and accelerator
What is an accelerator?
tertiary amine
What happens to the colour of the material when exposed to natural light?
changes colour due to oxidation
What is added to prevent the change in colour of the material when exposed to natural light?
prevented by the addition of ultraviolet absorber such as 2-hydroxy-4-methoxybenzophenone
Why do we need polymerisation inhibitors?
there will be the odd free radical being given off from the material naturally
dimethacrylate monomers polymerise in storage
What polymerisation inhibitor is added? and what is the benefits of this?
monomethyl ether or hydroquinone
- prevents premature setting
- increase the materials shelf-life
Can resin be seen on a radiograph?
no, it is radiolucent
Do you want radiopacity with restorative materials?
yes, ant them to be seen on a radiograph
What radiopaque materials are added to restorative materials?
heavy metal derivatives are used
such as; barium, zinc, strontium and yyerbium
What is added to the restorative material to get a natural tooth colour?
pigments and opacifiers
inorganic oxide compounds such as iron oxides are added to the resin in small quantities
