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Influence of photoactivation method on conversion, mechanical properties, degradation in ethanol and contraction stress of resin-based materials

2005; Elsevier BV; Volume: 33; Issue: 9 Linguagem: Inglês

10.1016/j.jdent.2005.02.005

1879-176X

Marcelo Ferreira Witzel, Fernanda Calabró Calheiros, Flávia Gonçalves, Yoshio Kawano, Roberto Ruggiero Braga,

Additive Manufacturing and 3D Printing Technologies

To investigate the influence of photoactivation method on degree of conversion (DC), flexural strength (FS), flexural modulus (FM) and Knoop hardness (KHN) of a composite and an unfilled resin (Filtek Z250 and Scotchbond multi-purpose plus, 3 M ESPE) after storage in water or ethanol, and on composite contraction stress (CS). Specimens 1×2×10 mm were prepared for FS test, photoactivated by 600 mW/cm2×40 s (A), 200 mW/cm2×120 s (B), or 600 mW/cm2×1 s +3 min delay +600 mW/cm2×39 s (C), and tested after 24 h in water or ethanol. Load and displacement values were used to calculate FM. Specimen fragments were used to measure KHN. DC was determined by FT-Raman spectroscopy. CS was determined by mechanical testing. Data were submitted to ANOVA/Tukey's test (α=0.05). Composite DC was not affected by photoactivation (A: 65±1.8%; B: 66±3.4%; C: 65±2.9%). Unfilled resin DC was statistically higher using method A (79±0.3%) than B (74±1.0%) and C (73±0.9%). Photoactivation did not influence composite properties, regardless of the storage medium (p>0.05). After ethanol storage, FS of the unfilled resin was lower for specimens irradiated by method B (p<0.001). Pulse-delay curing (C) significantly reduced CS (7.7±1.3 MPa), compared to A (10.7±1.2 MPa) and B (10.1±1.3 MPa). Photoactivation method did not affect composite properties or susceptibility to ethanol degradation. For the unfilled resin, DC was lower with the use of low intensity and pulse-curing, while FS after ethanol storage was reduced by low intensity curing. Pulse-delay curing significantly reduced CS.