Delayed light‐curing of dual‐cure bulk‐fill composites on internal adaptation and depth of cure

Abstract

AbstractObjectiveTo evaluate the effect of delayed light‐curing of dual‐cure bulk‐fill composites on internal adaptation and microhardness (KHN) in depth.Materials and MethodsBulk‐fill composites were placed in 35 box‐shaped preparations and cured according to the following protocols (n = 5): Filtek Bulk‐Fill light‐cured immediately after insertion (FBF); Bulk‐EZ light‐cured immediately after insertion (BEZ‐I); Bulk‐EZ light‐cured 90 s after insertion (BEZ‐DP); Bulk‐EZ self‐cured (BEZ‐SC); HyperFIL light‐cured immediately after insertion (HF‐I); HyperFIL light‐cured 90 s after insertion (HF‐DP); HyperFIL self‐cured (HF‐SC). After 24 h, the samples were axially sectioned, and the internal adaptation was evaluated using replicas under a scanning electron microscope. The KHN was evaluated at six depths (0.3 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). The statistical analysis was performed using α = 0.05.ResultsThe KHN significantly decreased with depth, except in self‐curing mode, when it was similar at all depths. Delayed light‐curing significantly increased the KHN at higher depths. The internal adaptation was material‐dependent. Light‐curing did not influence the internal adaptation of HyperFIL, whereas delayed light‐curing significantly reduced the internal gaps (%) of Bulk‐EZ.ConclusionDelayed light‐curing improved the depth of cure of dual‐cure resin composites. Light‐curing did not influence the internal adaptation of HyperFIL, but delayed light‐curing improved the internal adaptation of Bulk‐EZ.Clinical SignificanceLight‐curing is fundamental for improving the mechanical properties of dual‐cure resin composites. Moreover, depending on the dual‐cure resin composite, the delay in light‐curing can reduce the internal gaps.