composite resin Flashcards
in dental composite, resin matrix phase is reinforced by dispersed ___ particle phase bound to the resin by a ________ and an initiator-accelerator system
filler particle phase
bound to resin by a silane coupling agent
bis-GMA (most widely used)
UDMA
TEGDMA
resin matrix
what is silica
a filler particle dispersed in resin matrix and need this for composite
-reinforcement of resin matrix
-decreased polymerization shrinkage
-decreased thermal expansion and contraction
-viscosity control
-decreased water sorption
-increased radiopacity
benefits of filler particles
monomers to be converted into polymers
and process is triggered by
composites
by free radicals (heat, light)
BHT andd hydroquinone
polymerization inhibitor
metal oxides=
=pigments
3 classifications of composities
- filler particle size and size distribution
- handling characteristics
- type of polymerization
what type of force breaks brittle materials (when they are weakest)
tensile strength (pulling)
where do caries spread more rapidly
in the dentin
tapered fissure bur
169
BURS CREATE INTERNAL ROUNDED LINE ANGLES
(UNDERCUTS)
245 AND 330
undercuts anything that converges
preserve marginal ridge and no undermined enamel (resistance)
divergence
retention of isthmus
converging
what carie fluoride protects again the most
smooth caries
type of hybrid filler we use now
mini-nano hybrid
packable composite:
flowable:
packable- medium viscosity
low viscosity
advantage is bulk placement
disadvantage is mixing
no control of working time
activator and initiator?
chemical cure
act- aromatic tertiary amine
init- benzoyl peroxide (BPO)
most common
adv- control of working time and no mixing
act and init?
light cure
act- blue ligiht
initiator- camphorquinone (468nm)
tip size of curing light?
smaller tip increases output and heat
oxygen inhibited layer is how many microns thick
15
stress level will vary depending on the type of restoration configuration factor:
higher this, higher stress
c factor
what will decrease c-factor
incremental placement. stress reduced not shrinkage
lower filler size=
higher surface finish
lower filler amount, higher water sorption=
higher expansion
bisGMA higher sorption
important to distinguish carious tissue and marginal adaptation, air bubbles (defects)
radopacity
removes minerals from dental substrate
allowing adhesive infiltration
acid etching
phosphate monomer that chemically interacts via ionic bonding to calcium in hydroxyapatite
1-MDP (chemical bonding)
