Retreatability of three calcium silicate-containing sealers and one epoxy resin-based root canal sealer with four different root canal instruments

The objective of the study was to compare the retreatability of three calcium silicate-containing sealers (BioRoot RCS, MTA Fillapex, Endo C.P.M.) and an epoxy resin-based sealer (AH Plus) with different root canal instruments (Hedstrom files, Reciproc R40, Mtwo retreatment file R 25/.05 + Mtwo 40/.06, and F6 SkyTaper) concerning sealer remnants and retreatment time. Root canals of 192 teeth were instrumented with Reciproc R40. All root canals were obturated using the single-cone technique with Reciproc R40 gutta-percha and one of the sealers (n = 48 per sealer). Two months later, retreatment was performed using one of the mentioned instruments (n = 12 per instrument and sealer). The roots were split longitudinally, and both halves were investigated using light microscopy. The percentage of sealer remnants covering the root canal wall was evaluated using the software ImageJ. The time required for retreatment was recorded. Statistical analysis was performed using two-way ANOVA and Student-Newman-Keuls post hoc test. Regarding the percentage of root canal filling remnants as well as retreatment time, two-way ANOVA indicated that the results were significantly affected by the sealer (p < 0.001) and by the instrument used (p < 0.05). Overall, the use of AH Plus was associated with significantly more remnants compared to all other sealers (p < 0.001) and F6 SkyTaper instruments allowed significantly faster retreatment than the other instruments (p < 0.05). The retreatability of calcium silicate-containing sealers was better compared to AH Plus as less sealer remnants and shorter retreatment times were observed. Retreatment with engine-driven NiTi instruments was superior compared to hand instrumentation. Engine-driven NiTi instruments are better suited to remove root canal fillings than stainless steel Hedstrom files.