Figure 1.

Digital radiographs of the test (a,c) and the control fibrin hydrogel (b) under investigation. A cross-section of a human incisor crown was used as a reference. A photograph of the set-up is depicted in the insert. The aluminum step-wedge had a thickness of 0.5, 1, 1.5, 2, and then 3 mm Al, followed by 1 mm steps. As can be appreciated from this figure, the test hydrogel (a) had a radiopacity of ~2 mm Al/mm, whilst the control hydrogel (b) displayed no radiopacity (dotted lines). Freshly mixed test hydrogel containing iodixanol was placed in the root canal system of immature human premolars using a lentulo spiral (c). This test hydrogel apparently filled the whole canal space and could be clearly discerned from root dentin.