Pre- and postoperative images were analysed for the percentage of unprepared canal areas and the percentage of removed dentine. The mechanical preparation time for each sample was recorded.

06v taper), both following the manufacturer's instructions, or XP-endo Shaper following a new protocol with extended activation time. Micro-CT scans were taken before and after canals were instrumented using WaveOne Gold (size 35. The samples were randomly divided into three groups (n = 10). The normality of canal length, curvature angle, volume, surface area, structure model index, and aspect ratio were confirmed. Thirty moderately curved oval-shaped distal roots of mandibular molars were selected. To compare the shaping ability of a heat-treated centric reciprocating file system (WaveOne Gold), a heat-treated eccentric rotary multifile system (TRUShape 3D Conforming Files), and a heat-treated expandable one-file rotary system (XP-endo Shaper) extending its activation time, in preparing oval-shaped root canals in extracted mandibular molars by means of microcomputed tomography (micro-CT) analysis.

Wave one endo