Compoaite Resin - Consituents And Properties Flashcards
Most composite resins are based on this product
Bis-GMA (addition product of bisphenol and glycidylmethacrylate) or urethane dimethacrylate + diluent monomer, triethylene glycol dimethacrylate (TEGMA)
Products such as quartz, Fused silica, glasses such as aluminosilicate and borosilicate adds the following properties to the composite resin
Compressive strength, abrasion resistance, modulus of Elasticity,fracture toughness, thermal expansion, single contraction,aesthetic qualities
Contains particles of radiopaque barium or strontium Glass 2.5- 5 micrometres in size to give 75 to 80% by weight of filler.
Mechanical properties are good but hard to polish and soon Roughens
Macrofilled or conventional
Contains colloidal silica particles 0.04 micro meters in size and 30 to 60% by weight.
Retains a good surface polish that is unsuitable for load-bearing situations, has poor wear resistance and increase contraction shrinkage
Microfilled composite resins
By combining Nanometric particles and nano clusters in conventional resin Matrixx, manufactures claim to offer increased wear resistance and polishability and Lustre
Nanofilled composite resins
It contains a mixture of conventional and microfine particles designed to optimise both mechanical and surface properties.
Contains 75 to 85% by weight of filler, of which the bulk is conventional I.e 1 to 50 micrometers some manufacturers achieve up to 90% filler loadings by using blended size of filler particles
Hybrid composites
These are developed to stimulate the condensation of amalgam although no decrease in volume as compressed therefore not strictly condensed.
Resin and ceramic fillers are incorporated into a network of ceramic fibres.
Claim to have increased wear resistance and less polymerisation shrinkage.
Packable (condensable)
Chemically cured: benzoyl peroxide or sulfunic acid 
Initiator + tertiary amine activator
Light cured: amine + diketone activated by this wavelength
Blue light 460-470 nm
Classification
Microfilled Posterior composite all-purpose flowable condensable or packable
Polymerisation shrinkage
1-4%
Elastic modulus of this composite is greater than the other composite resins, amalgam
Hybrid
Types of light source for curing
QTH, PAC, LED
LED WIDELY USED REPLACING QTH
Products used to refine
Microfine diamond
Multibladed tungstun carbide finishing bur under water spray
Shofu points or finishing pastes for inaccessible areas
The ratio of bonded to unbonded surfaces in a cavity. The higher this is, The more likely the risk of effects of polymerisation shrinkage leading to bond failure, cuspal deflection post-operative sensitivity.
C factor (configuration)
They Allow command setting. They overcome the moisture sensitivity and low early mechanical strength associated with conventional GI.
The acid base reaction of GI is supplemented by the addition of 75% resin which is hydroxyethylmethacrylate bis GMA.
Used in deep carious lesions
RMGIC
Poly acid modified resin.
Combines the adhesive and fluoride releasing properties of GI with the abrasion resistance of composite resin and it’s called with a touch of originality -
Used in pediatric patients
Compomer
Composite resin with active GI filler particles
Giomers
Organically modified ceramics
Ormocers
They are similar to GIs except that the ion leachable glass is fused with fine silver powder. Mixing with a polymeric acid gives a cement consisting of unreactive glass particles with silver as fused, held together by a metal salt Matrixx with the benefit of increased wear resistance
Cermets
Silanised monohybrid fillers embedded ina light curing organic matrix
Used in indirect onlays
Ceromers
