Autumn quiz: Composites, curing lights and adhesives Flashcards
what are the 3 general parts to composite
- resins/initiators (make resin polymerize/harden)
- coupling agent (connects resin to filler materials)
- filler (comes in diff shapes/sizes)
what are the qualities of monomer resin
resin are materials that harden as they go from monomers to polymers
monomer resin is:
-weak
-poor wear resistance
-significant shrinkage
-hydrophobic once cured
-polymerization is inhibited by oxygen, this is just a surface phenomenon- finish and polish fixes that. this allows composite to stick to more composite tho..
what are the 3 major monomers resin
bis gma
udma
tegdma
—-> methacrylates?
what are initiators?
name some common ones- general expensiveness?
this is what we light cure to change monomer to polymer.
common ones:
-camphorquinone (CQ) + tertiary amine (cheap.yellowish)
-1-phenyl-1,2-propanedione (PPD)
-2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO)
-Both PPD and TPO are lighter color (better coloring) but more expensive and more restrictive absoprtion range
what does light do to initiators
makes them interact w monomers to make polymers (light within a specific range freq)
describe the chemical process of polymerization of resin monomers
-free radical creation caused by light, breaking down an unstable covalent bond, leaving two interactive/reactive free radicals.
-the free radicals react with double bonds on monomers- chain reaction of polymerization. ends when reactive monomers run out of other unreactive monomers to link with
chains take up less space than monomers- always shrinkage
shrinkage is about 7% if not filled in the hole.???
???
what is dual-cure composite, whats it good for?
dual cure composites- taking two separate composites- one that is light, one that is chemical cured and combing
good for deep cavities and bulk fill (dont want to do in increments)
what is the chem reaction of dual-cure?
one paste has benzoyl peroxide (BP) other has aromatic tertiary amines
-light cure by CQ (camphorquinine)/amine reaction
or will react with benzoylperoxide for chemical cure/amine reaction also
light can penetrate 2 mm, deeper, chemical helps to solidify.
what is silane used for
its a coupling agent
dual sided; one reaction with glass (filler) and the other end has a covalent or organic bond reacting with resin material.
-silane molecules bond resin to filler.
whats the purposes of filler in composite
- improves fracture resistance (biggest one)
- reduces polymerization shrinkage
- impart color and opacity
- improve radiopacity
pretty much all made up of glass/silica
what are the components of filler ?
- glass/quartz (barium oxide glass, ba-al-fluorosilicate, dispersed silica)
- metal oxide (gives opacity, radiopacity, color) typical medals include aluminum, cobalt, chromium, magnesium, silicon and iron..
what are the features of MACROFILL, whats its uses?
around since 1960s
- large and irregular (8-12 micrometers)
- good fracture resistance
- poor polish
- poor wear resistance
- low shrinkage
- horrible old anterior composites (opaque)
- milled
uses: crown build up materials, rockcore?, chemical or dual cure
(aesthetics dont matter, big hole)
whats microfill/whats its uses and features
made in 1970s
- spherical shape for handling and aesthetics (more likely to fracture, higher shrinkage rate)
- colloidal silica particles
- 55% filled
- high polish
- poor fracture resistance
- good wear resistance
- high shrinkage (low fill)
- heat created
- uses; composite veneers, carious or non carious cervical lesions.
whats microhybrid /features and uses
- 1st UNIVERSAL composite, 1880s-90s
- mix of glass and ceramic particles (.6-2 microns)
- 70-77% filled; highly filled!
- low shrinkage
- good polish
- good wear resistance
- uses: universal application, anterior ANd posterior, good range of opacities and shades
whats nanofill/uses and features
- nano clusters
- .001 - .01 microns
- allows DENSE filling with good flow
- increase fill rate without stiffening