## 3 Results  
### Study Selection and Characteristics  
The research through the PubMed, Cochrane Library, and Scopus databases identified a total of 51 citations and, after examining titles, abstracts, and full texts, only 17 articles were eligible for inclusion in this paper. Twelve articles were excluded based on the title, twelve based on the abstract, nine after reading the full text, and one because it was written in Japanese. The included studies were consequently submitted to quality assessment (using the Newcastle-Ottawa Scale) and data extraction.  
This research selected 17 randomized controlled trials, whose characteristics are presented in Table 2, with reference to author and year of publication, study design, remaining root filling material measured, and irrigation protocols compared with XP-Endo Finisher. All of the articles were written in English language.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Study**} & \multirow{2}{*}{**Design**} & \multicolumn{2}{c}{**Remaining Root Filling Material Measured**} & \multicolumn{1}{c}{**Inrigation Protocols Compared with XP-Endo**} \\  & & & & **Finisher** \\ \hline \multirow{3}{*}{[PERSON] et al., 2016} & \multirow{3}{*}{RCT} & \multirow{3}{*}{Bacteria in mandibular molars} & 2.5\% _NaOCI agitation_: \\  & & & - & PUI \\  & & & - & XPF \\ \hline \multirow{3}{*}{[PERSON] et al., 2016} & \multirow{3}{*}{RCT} & \multirow{3}{*}{Bacteria colonized in dental tubules} & 17\% _EDTA_ + 6\% _NaOCI agitation with:_ \\  & & & - & CNI (no activation) \\  & & & - & EndoActivator \\  & & & - & Er:YAG \\  & & & - & XPF \\ \hline \multirow{3}{*}{[PERSON] et al., 2017} & \multirow{3}{*}{RCT} & \multirow{3}{*}{Biofilm in apical root of single rooted pre molars} & \multicolumn{1}{c}{_Three-step irrigation_:} \\  & & & - & CNI (no activation) \\  & & & - & PUI \\  & & & - & XPF \\ \hline \multirow{3}{*}{[PERSON] et al., 2019} & \multirow{3}{*}{RCT} & \multirow{3}{*}{AHTD in oval-shaped canals} & 5.25\% _NaOCI agitation + final flush with 17\% EDTA for 2 min and bi-distilled water_: \\  & & & - & PUI \\  & & & - & PUI \\  & & & - & 5.25\% _NaOCI agitation with:_ \\  & & & - & XPF \\ \hline \multirow{3}{*}{[PERSON] et al., 2019} & \multirow{3}{*}{RCT} & \multirow{3}{*}{RCT} & 2.5\% _NaOCI (in the first cycle), 17\% EDTA (in the second one) agitation_: \\  & & & - & PUI \\  & & & - & XPF—R \\  & & & + _final flush with bi-distilled water_ \\ \hline \multirow{3}{*}{[PERSON] et al., 2017} & \multirow{3}{*}{RCT} & \multirow{3}{*}{Smear layer in curved canals} & - & CNI \\  & & & 17\% _EDTA agitation with:_ \\  & & & - & No additional agitation \\  & & & - & Agitated with BT2 file \\  & & & - & EndoActivator \\  & & & - & XPF \\  & & & + _2.5\% NaOCI + sterile saline solution_ \\ \hline \multirow{3}{*}{[PERSON] et al., 2016} & \multirow{3}{*}{RCT} & \multirow{3}{*}{Ca(OH)\({}_{2}\) in single-rooted teeth} & 2.5\% _NaOCI agitation with:_ \\  & & & - & Beveled needle (no activation) \\  & & & - & Double side-vented needle (no activation) \\  & & & - & CanalBrush \\  & & & - & XPF \\  & & & - & Sonic irrigation \\  & & & - & PUI \\  & & & - & Er:YAG laser \\ \hline \hline \end{tabular}
\end{table}
Table 2: List of included studies.  
_Appl. Sci._**2019**, \(9\), 5001  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
The outcome measures reported in this systematic review refer to a total sample of 828 teeth, of which 245 teeth were treated with XP-Endo Finisher, 230 with passive ultrasonic irrigation, 184 with convention needle irrigation, 45 with Er:YAG laser, 40 with EndoActivator, 40 with CanalBrush, 16 with TRUShape 3D, and 28 with Self-Adjusting File.