RESUMO
PURPOSE: This study was designed to compare the amount of polymerization shrinkage of dual-cure resin cements according to different polymerization modes and to determine the effect of light activation on the degree of polymerization. MATERIALS AND METHODS: Four kinds of dual-cure resin cements were investigated: Smartcem 2, Panavia F 2.0, Clearfil SA Luting and Zirconite. Each material was tested in three different polymerization modes: self-polymerization only, immediate light polymerization and 5 minutes-delayed light polymerization. The time-dependent polymerization shrinkage-strain was evaluated for 30 minutes by Bonded-disk method at 37degrees C. Five recordings of each material with three different modes were taken. Data were analyzed using one-way ANOVA and multiple comparison Scheffe'test (alpha=.05). RESULTS: All materials, except Panavia F 2.0, exhibited the highest polymerization shrinkage-strain through delayed light-activated polymerization. No significant difference between light activation modes was found with Panavia F 2.0. All materials exhibited more than 90% of polymerization rate in the immediate or delayed light activated group within 10 minutes. CONCLUSION: As a clinical implication of this study, the application of delayed light activation mode to dual-cure resin cements is advantageous in terms of degree of polymerization.
