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.