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Stress reduction in resin-based composites cured with a two-step light-curing unit
C P Ernst1, R Kürschner, G Rippin
1Department for Restorative Dentistry and Periodontology, Johannes Gutenberg-University Mainz, Germany. Ernst@mail.uni-mainz.de
Purpose:
To examine the stress reduction of different resin-based composites, cured with a two-step polymerization unit (Elipar Highlight) by means of a photoelastic investigation.
Materials And Methods:
For each material (Pertac II, Tetric Ceram, Charisma F, Solitaire, Dyract, Dyract AP, Definite), a minimum of 10 resin samples, embedded in acrylic-glass plates, were polymerized using a standard polymerization process of 700 mW/cm for 40 s. Another 10 samples were polymerized with a light output of 150 mW/cm2 for 10 s and then with a light output of 700 mW/cm2 for 30 s.
Results:
For Pertac II the reduction of polymerization stress in the two-step-mode was 15.5%, for Tetric Ceram 14.5%, for Solitaire 8.1%, for Dyract AP 6.5% and for Definite 4.7%. These differences in polymerization stress between the standard and two-step-polymerization mode were statistically significant (P < 0.01, Wilcoxon test). No statistically significant differences in polymerization stress could be found for Charisma F and Dyract.