“…After screening, 28 studies were considered eligible for full‐text appraisal (Figure 1). Further analysis revealed that 23 studies were excluded since 7 were laboratory‐based studies [12, 20–25], 2 studies assessed on postoperative pain reduction [26, 27], 9 studies were clinical trials assessing similar instrument design or hand instrumentation [27–35], 2 studies on self‐adjusting file (ReDent‐Nova, Ra′anana, Israel) (SAF) since these instruments could not be classified as eccentric or centric design [21, 36], 1 study evaluated an irrigation protocol [37], 1 study on root canal preparation analysis [38], 1 clinical trial on periapical healing [39]. Finally, 5 studies were included for this systematic review [40–44].…”