Sammanfattning
So-called bulk-fill resin composites have been introduced in order to fill deep cavities in one or two increments, thus simplifying an otherwise elaborate, incremental restorative procedure. The prerequisite for the use of bulk-fill composites is their claimed depth of polymerization of 4 mm, obtained mainly through modification of the photoinitiator system, thus allowing for placement of layers of 4 mm compared to the conventional 2 mm. This chapter describes and discusses the composition, the physical properties, and the clinical use of bulk-fill resin composites. Bulk-fill resin composites are available in low-viscosity (or flowable) and high-viscosity versions. Because of the lower filler volume needed to reduce the viscosity, low-viscosity materials have decreased strength and must therefore be covered by an occlusal layer of conventional resin composite. Such a covering layer also alleviates any aesthetic issue caused by the higher transparency or the limited number of shades of some low-viscosity materials. Studies of depth of polymerization and stress formation are still scarce, and results are often contradictory, hindering the possibility of drawing any clear-cut conclusions. Additional in vitro data and clinical studies are warranted, and in the meantime, dentists are advised to apply a sound, critical approach and stay well within the indications.