If we use a 0.6 file and gutta-percha with a 0.4 taper, can we say that the binding will occur apically?

It will occur more apically, but we cannot say that it will occur at the apex. If gutta-percha with an 02 taper is placed, it will occur even more apically. In most cases, as the taper of the gutta-percha decreases, the diameter of the master cone used for obturation needs to increase. When there is curvature apically during shaping, the files may not contact one wall of the canal. As a result, the canal at the apex may be wider than the diameter of our file. In this situation, when obturation is performed with a single cone with a high taper, gaps will remain apically. The sealer is expected to fill these gaps, but it cannot always do so. In this situation, placing an 02-tapered master cone can provide a better fit with a thicker size of gutta-percha.