TY - JOUR ID - TI - Post-gel polymerization shrinkage strain evaluation of four light-activated composites using different curing modes AU - Ali A. Razooki Al- Shekhli PY - 2009 VL - 21 IS - 2 SP - 14 EP - 17 JO - Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد SN - 18171869 23115270 AB - ABSTRACT
Background: One of the ways of minimizing polymerization shrinkage of light-activated composites is by applying
short pulses of light energy, prepolymerization at low light intensity followed by final cure at high intensity (soft-start
polymerization) or a combination of both. This study investigated the influence of different curing modes on the postgel
polymerization shrinkage strain of different light- activated composites.
Materials and methods: This study investigated the Post-Gel Polymerization Shrinkage Strain of two mm thick
composite specimens after exposure to different curing modes. Parameters included six conventional curing modes:
Control (C), Pulse Delay I (PDI), Pulse Delay II (PDII), Soft-start (SS), Pulse Cure I (PCI), and Pulse Cure II (PCII) plus three
experimental curing modes of higher energy density: Prolonged low-intensity pulse cure mode (PLPC), Prolonged
moderate-intensity pulse cure mode (PMPC) and Rapid high-intensity continues cure mode (RHCC) for each of the
four different light-activated composite materials (Tetric Ceram, Heliomolar, Herculite XRV and Degufill Mineral).
Results: Statistical analysis of the data by using the one-way analysis of variance revealed that, there was a
statistically significant difference for all the polymerization shrinkage strains with the composite type, curing mode
and post-curing-time.
Conclusion: Light intensity reduction and elongation of the curing time combined with pulse activation and soft start
polymerization (PLPC curing mode) resulted in significantly lower and gradual post-gel polymerization shrinkage strain
for all the light-activated composites being tested
Key words: Post-gel polymerization, Light curing modes, Polymerization Shrinkage strain. J Bagh Coll Dentistry 2009;
21(2):14-17)

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