| Summary: | The behavior of curing heat of in light-cured restorative composite
resins, containing bis-GMA and 3G, was investigated by differential
scanning calorimetry (DSC). Visible light-activated polymerization of these
monomer systems was studied using camphorquinone (CQ) and dimethylaminoethyl
methacrylate (DMAEMA) as reducing agent. In particular, DSC
can be easily used to measure the heat of polymerization because of the
easy features in the sample preparation. Four samples of a visible lightcured
restorative composite resin (two of them unfilled and two filled) were
studied at two different light exposition times. The used materials in this
study were bis-GMA, 2,2-bis[p-g-methacryloxy-b-hydroxypropoxy)phenyl]-
propane; 3G, triethylene glycol dimethacrylate; CQ, camphorquinone and
DMAEMA, dimethylaminoethyl+methacrylate. The two filled composites
were prepared with silicium dioxide (77 wt %, 30 µm particle size average).
A system of thermal analysis Mettler TA-3000, DSC-30 was used to carry
out measurements, in an isothermal segment at 37 oC during 5 min under a
controlled thermal program. The specimens were polymerized by illuminating
them in a DSC apparatus with radiation from a visible light
source (Heliolux II) for 0.33 and 0.67 min and the heat output was determined.
It seems that the exothermic peak of the DSC curve for lightcured
resins depend on the heat of polymerization of each monomer itself contained
in the resins.
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