Post-gel polymerization shrinkage strain of four different light-activated composites polymerized with different curing modes

Abstract

Background: This study investigated the influence of different new curing modes on the post-gel 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 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 is statistically very highly 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