“…This method has been extensively used since the early 1970s mostly to evaluate the adaptation of filling materials to the canal walls (Abramovich & Goldberg, 1976; Balguerie et al, 2011; Coviello et al, 1977; Fromme & Riedel, 1972; Gibby et al, 2011; Lester & Boyde, 1977; Mannocci et al, 1998; Patri et al, 2020; Russell et al, 2018; Sevimay & Dalat, 2003; Torabinejad et al, 1978; Wollard et al, 1976) and to measure the penetration of gutta‐percha and/or sealer into the dentinal tubules (Balguerie et al, 2011; Caceres et al, 2021; Çalt & Serper, 1999; Gutmann, 1993; Hashmi et al, 2019; Kokkas et al, 2004; Kouvas et al, 1998; Mamootil & Messer, 2007; Okşan et al, 1993; Oliveira et al, 2017; Sevimay & Dalat, 2003; Shokouhinejad et al, 2011; Vassiliadis et al, 1994) (Figure 34). Overall, results from these studies revealed that (i) the tubular depth penetration and adaptation of filling materials to the root canal walls appear to be influenced by their physicochemical characteristics, (ii) the presence of smear layer or residual interappointment medication at the root canal walls obstruct the penetration of sealers into the dentinal tubules, (iii) resin‐based sealers usually display deeper and more consistent penetration into the dentinal tubules, and (iv) sealer penetration into the dentinal tubules can be improved by sonic irrigant activation.…”