## 4 Discussion  
Since [PERSON] et al. [23] discovered that the pH level of CaOH was higher when it was activated with ultrasound and suggested that this was due to the increased penetration of calcium hydroxide inside dental tubules, other investigations have been carried out in order to assess the effect produced by the ultrasonic or sonic activation of different obturation materials. There does not appear to be any controversy regarding the ultrasonic activation of cement producing a significantly higher tubular penetration of sealers [11; 12; 24; 25; 26]. Nevertheless, sonic activation has been questioned. In research conducted by [PERSON] et al. [12], the authors observed that, although ultrasonic activation of the cement had the best results, regarding the penetration of sealer into lateral canals, sealer sonic activation exhibited better performance than the non-activated group. On the other hand, sonic activation has been shown to have the same effect as the control group of non-activation of the cement [26]. The results of the present investigation show that sonic activation had an influence on the tubular penetration of the EndoSequence BC sealer and this could be due to some differences in the methodology; [PERSON] et al. [26] explained that differences in their results compared with those obtained by [PERSON] et al. [12] could be due to worse performance of the cement when activated for a longer period with a sonic device. As in [PERSON] et al. [12], the time taken for activating the sealer was 10 s in our study. In contrast, [PERSON] and [PERSON] [25], found worse results when activating with Endoactivator for 5 s. This could suggest that the time spent using the Endoactivator is a factor of crucial importance and possibly directly related to the heat generated. It is assumed that heat could accelerate the hydration of a biocearamic sealer and influence some of its properties, such as setting time, flow, or porosity [27]. [PERSON] et al. [28] observed that MTA plus had a lower bond strength when used with a continuous-wave obturation technique compared with a single-cone technique. Nevertheless, in another study [29], where both techniques were assessed, they found similar results for tubular penetration of tricalcium silicate sealers; however, as in our study, these authors did not examine the interface between the gutta-percha and the dentin wall. In addition to these methodological differences, [PERSON] et al. [26] utilized straight canals with an apical diameter #50/0.02 taper in which the activator tip was considerably smaller than the width of the canals. In the present study, activator tips used were size #25/0.04, which were manually and loosely fitted within 2 mm of the working length, as per the manufacturer's recommendation, into #30/0.04 canals. Besides this, it has been demonstrated that the ultrasonic activation of irrigants can improve the efficacy of those in removing both organic and inorganic debris from root canal walls [30; 31; 32], releasing debris from the tubules and allowing the sealer to penetrate. For this reason, we used \begin{table}
\begin{tabular}{c c c c c c} \hline \multicolumn{6}{c}{**Infiltration (\%)**} & \multicolumn{3}{c}{**Maximum Infiltration (\(\mu\)m)**} \\ \hline \multicolumn{6}{c}{**Experimental Group**} \\ \hline
**Level** & **BC\(-\)** & **BC+** & **\(p\)-Value** & **BC\(-\)** & **BC+** & \(p\)-Value** \\ \hline
9 mm & 50.3 & 70.5 & 0.030 & 239.9 & 291.1 & 0.037 \\  & (37.49/67.85) & (53.54/75.11) & & (176.8/304.3) & (242.7/368) & 0.044 \\
6 mm & 57.1 & 64.6 & 0.474 & 193.8 & 260.2 & 0.044 \\  & (41.14/65.85) & (44.44/70.8) & & (175.9/248.4) & (192.4/321.7) & 0.045 \\
3 mm & 47.8 & 49.7 & 0.653 & 105.6 & 193.1 & 0.005 \\  & (33.98/56.61) & (39.23/56.46) & & (68.16/189.5) & (112.2/221.7) & 0.005 \\ \hline \end{tabular}
\end{table} 
Table 1: Median (25% and 75% quartiles) of the infiltration (%) and maximum infiltration (\(\mu\)m) of the sealer in the 9, 6 and 3 mm levels of the tested groups. BC\(-\), no sonic activation; BC+, sonic.