A micro-computed tomographic analysis of retreatability of two bioceramic sealers using rotary instrumentation with supplementary irrigant agitation techniques

Hydraulic tricalcium silicate-based bioceramic materials have been recently introduced as root repair cements. The retreatability of Guttaflow Bioseal (Coltene Whaledent, Langenau, Germany) and BioRoot RCS (Septodont, Saint Maur des Fossés, France) has not been investigated thus far. Aim of this study was to evaluate the retreatability of two tricalcium silicatebased materials (BioRoot RCS and Guttaflow Bioseal,) using a combination of rotary instrumentation and supplementary irrigant agitation techniques (syringe irrigation, Tornado Brush and ultrasonically activated irrigation) by high-resolution micro-computed tomography. Methods: Single-rooted mandibular premolars were prepared to size 40/0.04 (Hyflex EDM rotary nickeltitanium instruments, Coltene, Coltene/Whaledent AG, Altstatten, Switzerland) and randomly divided into 2 experimental groups (n=24) depending on the root filling material. Root canals were filled with Guttaflow Bioseal (Group 1) or BioRoot RCS (Group 2), scanned using a microCT scanner (Skyscan1172, Brunker microCT, Antwerp, Belgium) at 80 kV and 100 μA with an isotropic resolution of 11 μm and stored in phosphate buffered saline for 4 months. In all the groups, the root filling was removed using the R-Endo nickel-titanium rotary instruments (MicroMega) according to the manufacturer recommended protocol. Then, the specimens were randomly allocated to one of the subgroups for supplementary irrigant agitation: subgroup A (syringe irrigation), subgroup B (Tornado Brush, M.I.B, France) and subgroup C (ultrasonically activated irrigation). Specimens were re-scanned with micro-CT to calculate the root canal volume and volume of remnant root filling material. The volume of root canal filling material between the groups prior to retreatment procedures was compared using one-way ANOVA. To determine the effect of material and irrigant agitation method on the volume of remnant root filling, two-way analysis of variance (ANOVA) was used with post hoc Tukey test (Prism 8.0; GraphPad Software, Inc, La Jolla, CA). The significance level was set at P=0.05. Results: The preliminary analysis of root canal volume for teeth filled with Guttaflow Bioseal and BioRoot RCS showed no statistically significant difference (P>0.05). Specimens filled with Guttaflow Bioseal showed significantly less remnants compared to BioRoot RCS (P<0.05). There was no significant difference between the supplementary irrigant agitation groups in the removal of Guttaflow Bioseal (P>0.05). In group 2 (BioRoot RCS), subgroups B (Tornado Brush) and C (ultrasonically activated irrigation) showed significantly less remnant compared to syringe irrigation (P<0.05), with no significant difference between the two (P>0.05). Conclusion: Guttaflow Bioseal demonstrated superior retreatability than BioRoot RCS, 4 months after root filling. Supplementary irrigant agitation techniques did not influence the removal of Guttaflow Bioseal.