RESUMEN
AIM: To evaluate the shaping ability of the single-file XP-endo Shaper system (XP-S; FKG Dentaire, La Chaux-de-Fonds, Switzerland) employing a different working time and of the multiple-file ProTaper Next system (Dentsply Sirona, Ballaigues, Switzerland) using micro-computed tomography (micro-CT) technology. METHODOLOGY: Twenty long oval-shaped canals in mandibular incisors were matched anatomically and scanned by micro-CT (Skyscan 1172; Bruker micro-CT, Kontich, Belgium). The canals were divided into two groups (n = 10) according to the canal preparation protocol: XP-endo Shaper (XP-S) with an extra 45 s of instrumentation and ProTaper Next (PTN X4). The images recorded before and after preparation were evaluated for morphometric measures of volume, surface area, structure model index and untouched walls. The data were compared statistically (Student's t-test for homogenous variances and Mann-Whitney test) between the two groups (XP-S and PTN X4) at α = 5%. RESULTS: Root canal preparation significantly increased all parameters (volume, surface area, structure model index and untouched walls) tested in each group (P < 0.05). There was no significant difference (P > 0.05) in the percentage increase of volume (107.50%-93.13%), surface area (27.74%-29.68%) or untouched canal wall (13.08%-11.74%) between XP-S and PTN X4, respectively. CONCLUSIONS: The XP-endo Shaper system (single-file) with an extra 45 s of instrumentation and the ProTaper Next system (multiple files) had a similar root canal shaping ability. Neither technique was able to fully prepare the long oval-shaped canals of mandibular incisors.