Figure 1.

Photomicrographs of the biofilm on the surface of endodontic files, showing active cells (fluorescent green) and dead cells (fluorescent red) from the epifluorescence microscope: UEF-3 sample (a and b) with a predominance of dead cells; UEF-4 sample (c) with the absence of dead cells and with the biofilm image appearing in the shape of a Hedströem file spiral with overlapping cones; and UEF-2 (d) and UEF-1 (e) samples with a balance between dead and active cells.