7. PROPERTIES OF COMPOSITES
•Coefficient of thermal expansion – 3 times higher than normal tooth,
micro fills show more .
•Water absorption – high filler content lower is the water absorption.
•Wear resistance – prone to wear, it is effected by size, shape & content of
filler.
•Surface texture – size & composition of filler determines smoothness.
•Radiopacity – resins are translucent, fillers like barium, glass, strontium &
zirconium makes it radiopaque.
•Solubility - there is no significant solubility , 0.5-1.1 mg/cm3 water solubility
•Polymerization shrinkage - shrinks while curing.
•C-factor – it’s the ratio of bonded surface of restoration to unbonded
surface, high value shows greater shrinkage.
•Aesthetics – translucent, available in variety of shades.
8. POLYMERIZATION OF
COMPOSITES
It depend upon the following factors
•Curing time – short exposure time cause accelerated ratio of curing which
leads to substantial stress buildup
•Shade of composite – dark shade require long curing time
•Distance & Angle b/w light source & Resin – angle of source should be at
90 degree to resin, if angle diverges from 90 degree.
•Temperature – composite curing would be less if they are taken but
immediately from refrigerator.
•ResinThickness – It should be ideally 0.5-0.1 mm for optimum
polymerization of resin
•Inhibition Of Air – O2 in air also effects the polymerization of resin.
•Intensity Of Curing Light – for optimal results wavelength of light should
range b/w 400-500 mm
•Type Of Filler – micro fine composites are more difficult to cure than
heavily loaded.
9. APPLICATION OF COMPOSITES
TYPE OF RESTORATION
RECOMMENDED RESIN
COMPOSITE
CLASS I – CLASSV
CLASSVI
CERVICAL LESIONS
&PEDIATRIC
RESTORATIONS
3 UNIT BRIDGEOR CROWN
ALLOY SUBSTRUCTURE
CORE BUILD UP
TEMPORARY RESTORATION
HIGH CAVITY RESTORATION
MULTIPURPOSE, NANOCOMPOSITE,
PACKABLE MICROFILLED,
COMPOMERS.
PACKABLA NANOCOMPOSITES
FLOWABLE,COMPOMER
LABORATORY (FRC)
LABORATORY (BONDED)
CORE
PROVISIONAL
HYBRID COMPOSITE