Aim: To investigate whether Reciproc and Reciproc blue instruments (both VDW, Munich, Germany) are effective in re-treating a calcium-silicate–based sealer compared with re-treating an epoxy resin–based sealer. The time to reach patency (tp) and time to complete the re-treatment (tcr) were investigated as well as the amount of remaining filling material. Materials and methods: The root canals of 60 single-rooted teeth were obturated with either TopSeal (Dentsply Sirona, Ballaigues, Switzerland) or EndoSequence BC Sealer (Brasseler, Savannah, GA, USA). The teeth were randomly subdivided into four groups of 15 teeth for re-treatment with either a Reciproc R25 or a Reciproc blue R25: the epoxy Reciproc group (ER), the epoxy blue group (EB), the calcium-silicate Reciproc group (CSR) and the calcium-silicate blue group (CSB). During re-treatment the times were recorded and after re-treatment the remaining material was evaluated with radiographs. The experimentally obtained data were subjected to a two-way ANOVA. Results: Regarding the sealers, there were significant differences for tp (seconds) (mean calcium-silicate = 201.0; mean epoxy = 90.8; P 0.0001) and for tcr (seconds) (mean calcium-silicate = 326.4; mean epoxy = 229.7; P = 0.0003). Between the instruments there were no significant differences for tp (seconds) (mean Reciproc = 134.4; mean blue = 157.3; P = 0.1545) or for tcr (seconds) (mean Reciproc = 278.1; mean blue = 278.0; P = 0.9983). For the remaining material (%), there were no significant differences found (mean calcium-silicate = 2.06; mean epoxy = 1.69; P = 0.1623; and mean Reciproc = 1.84; mean blue = 1.91; P = 0.7965). Conclusions: It took longer to re-treat calcium-silicate sealers, but there were no significant differences in the amounts of remaining filling material. Both files were equally effective in re-treating root canals. Schlagwörter: calcium-silicate, endodontic sealer, epoxy resin, Reciproc, Reciproc blue, re-treatment