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The effect of combining photoinitiator systems on the color and curing profile of resin-based composites

2016; Elsevier BV; Volume: 32; Issue: 10 Linguagem: Inglês

10.1016/j.dental.2016.06.010

1879-0097

Dayane Carvalho Ramos Salles de Oliveira, Mateus Garcia Rocha, Ivo Carlos Corrêa, Américo Bortolazzo Correr, Jack L. Ferracane, Mário Alexandre Coelho Sinhoreti,

Additive Manufacturing and 3D Printing Technologies

To evaluate the effect of combining camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) on the color and curing profile of resin-based composites. Experimental composites were produced with different CQ and TPO molar concentrations: CQ-only, 3CQ:1TPO, 1CQ:1TPO, 1CQ:3TPO, and TPO-only. Polywave LED was characterized using a beam profiler. Block-shaped samples (5 mm × 5 mm × 3 mm depth) were cured in a custom-designed mold with a polywave LED positioned to compare the regions exposed to the 420–495 nm and 380–420 nm LED emittances. To map the cure profile, degree of conversion (DC) of longitudinal cross-sections from each block were evaluated by FT-NIR. Color, light-transmittance and light-absorption during curing were evaluated on specimens 1–3 mm thick. Data were analyzed using ANOVA/Tukey's test (α = 0.05; β = 0.2). Though the polywave LED beam profile was non-uniform, up to a depth of 2 mm no differences in DC were found among the composites containing CQ with TPO added up to 50%, regardless of the position under the curing tip. Composites with higher TPO concentration showed a decrease in DC beginning with a depth of 1 mm, while composites with higher or similar CQ concentrations did not show decreased DC until a depth of 3 mm. Higher TPO concentration reduced initial yellowness and color change after curing; and lower CQ concentration decreased light-absorption at greater depths. The combination of CQ with TPO added up to 50% reduced the yellowness and color change of composites after curing without affecting cure efficiency up to a depth of 2 mm.