Effect of Bioceramic-Based Obturation Techniques on the Amount of Residual Filling Material after Retreatment: An In Vitro Study

The aim of this article is to quantitatively assess the amount and distribution of residual filling after retreatment of root canals obturated with a bioceramic sealer using three obturation techniques: single-cone technique (SCT), warm vertical compaction (WVC), and cold lateral compaction (CLC).Forty-two mandibular premolars were prepared up to size F4 and randomly assigned to SCT, WVC, or CLC (<i>n</i> = 14/group). All canals were obturated with a bioceramic sealer. After storage for 15 days at 37 °C, retreatment was performed using the ProTaper Universal Retreatment (PTUR) without solvent. Roots were sectioned longitudinally, and residual fillings in coronal, middle, and apical thirds were quantified using stereomicroscopy and analyzed with ImageJ. Intra-examiner reliability was assessed using intraclass correlation coefficients.Nonparametric Kruskal-Wallis test was used to compare residual filling percentages among the three techniques, followed by pairwise comparisons with the Mann-Whitney <i>U</i>-test. Statistical significance was set at <i>α</i> = 0.05.No statistically significant differences were observed among the three obturation techniques in the percentage of remaining fillings (<i>p</i> = 0.0657). SCT exhibited the highest percentage of residuals (86.31 ± 14.49%), and CLC the lowest (62.66 ± 31.90%). All techniques exhibited a progressive increase in residuals toward the apical third.None of the obturation techniques allowed complete removal of bioceramic-based fillings after retreatment with PTUR. Although differences were not statistically significant, CLC was associated with the lowest amount of residuals, whereas SCT exhibited the highest. The apical third remained the most challenging region to clean across all techniques.