Should I use a filled or an unfilled resin adhesive?

Some adhesives are filled with glass, silica or nano-particles and some are unfilled. The advantage of a filled adhesive is that it could potentially be stronger than an unfilled adhesive. However, because of the size of some filler particles, the adhesive layer could be thicker than that of an unfilled adhesive. Futurabond DC (VOCO) is filled with 20-nanometer filler particles. The size of these particles could provide a lower film thickness than the layer of a typical filled adhesive, yet still provide more strength than unfilled adhesives. This adhesive can be used with direct light-, dual-, or self-cured composite restorations and core build-ups, with cementation of posts and indirect restorations.