Dentine Integrity and Shaping Ability of 3 Single‐File Systems in Flat‐Shaped Canals

Aim This study aimed to compare the shaping ability of 3 single‐file systems in flat‐shaped canals. Methodology Thirty‐six extracted mandibular incisors with flat‐shaped canals were anatomically matched using micro‐CT technology and assigned to three groups ( n = 12) based on the single‐file system used for root canal preparation: 1.5‐mm SAF Infinitum, Reciproc Blue R25, or XP‐endo Rise Shaper. After a new micro‐CT scan, pre‐ and post‐preparation datasets were co‐registered and analysed to quantify changes in canal volume, surface area, unprepared canal areas, dentine thickness and hard‐tissue debris volume. Parametric (One‐way ANOVA, Student's t ‐test for repeated measures) and non‐parametric (Kruskal–Wallis and Wilcoxon Signed Rank) tests were applied for statistical comparisons ( α = 5%). Results All groups showed significant increases in canal volume and surface area and reductions in unprepared canal areas after each preparation step ( p < 0.05), with no significant differences among SAF Infinitum, Reciproc Blue and XP‐endo Rise Shaper in shaping parameters at any time point ( p > 0.05). Dentine thickness significantly decreased over time in all groups ( p < 0.001), except for Reciproc at the buccal pericervical region and lingual midroot ( p > 0.05), with greater reductions in the lingual pericervical region (SAF Infinitum) and mesiodistal mid‐root level (Reciproc Blue and XP‐endo Rise Shaper) ( p < 0.05). Critically thin dentine areas (< 0.5 mm) were only observed mesiodistally at the mid‐root level after preparation. Hard‐tissue debris volumes did not differ significantly among groups ( p > 0.05). Conclusions SAF Infinitum, Reciproc Blue and XP‐endo Rise Shaper systems provide comparable shaping performance and dentine preservation in flat‐shaped canals. While all systems cause some dentine thinning, critically thin areas remained limited and localised.