Effect of different canal shaping and obturation techniques on retreatment efficacy: An in vitro study

Purpose: This study aimed to evaluate the effect of different canal shaping and obturation techniques on retreatment efficacy by analyzing the weight of removed filling material, retreatment time, and surface area reduction.
Methods: Eighty standardized acrylic resin blocks were shaped using four endodontic file systems [Pro-Taper Next (PTN), ProTaper Ultimate (PTU), VDW Rotate (VR), and XP-endo Shaper (XPS)] and obturated with either single-cone (SC) or continuous wave compaction (CWC), forming eight experimental groups (n=10). All samples were retreated using a single-file system. The amount of removed material was measured with a precision balance, time was recorded in seconds, and surface cleanliness was assessed using ImageJ software. Data were analyzed using the Kruskal–Wallis test followed by Bonferroni-adjusted pairwise comparisons.
Results: Statistically significant differences were found among groups for all parameters. XPS/SC and PTN/SC removed significantly more filling material than PTU/CWC and XPS/CWC. Retreatment times were significantly longer in XPS/SC and PTN/SC, and significantly shorter in PTU/CWC and XPS/CWC. For surface area reduction, PTU/CWC and XPS/CWC achieved the highest values, with CWC groups generally outperforming SC groups in cleanliness. Weight reduction correlated positively with time, while time correlated negatively with surface area reduction.
Conclusion: Retreatment efficacy is significantly influenced by the initial shaping and obturation technique. CWC generally resulted in shorter retreatment times and greater surface cleanliness, whereas SC groups tended to have greater filling removal by weight.

Keywords: Obturation, retreatment, root canal treatment, shaping.