All obturation techniques require a certain amount of root canal sealers in order to fill small irregularities along the canal wall. Epoxy resin-based sealers have been the gold standard to date. A more recent development is represented by calcium silicate-based sealers (CSS), which derive from calcium silicate-based cements (MTA). CSS are proven to be biocompatible and bioactive. A hydroxyapatite-like precipitate forms on the surface of CSS when they come in contact with tissue fluid so that these sealers are not recognized as foreign bodies, even in cases of sealer extrusion. After their setting, CSS release OH- and Ca2 ions over a longer period of time through which they potentially exhibit certain antibacterial effects and support the healing of periapical inflammation. For this reason, consideration has been given to the idea of filling root canals mainly with CSS and minimizing the proportion of gutta-percha. To date, however, no long-term clinical studies have been performed to confirm the advantages of this new concept. Although gutta-percha has been successfully used for root canal obturation for a very long time, there are different perspectives with regard to which root canal filling technique is better: cold or warm (thermoplastic) obturation. After the exposure of sufficiently filled root canals with saliva, microorganisms always infiltrate into the root canal system regardless of the obturation method. Until now, no known obturation method leads to a bacteria-proof sealing of the root canal. Thus, in terms of clinical success rates, no superiority of the frequently recommended thermoplastic root canal filling technique compared with cold lateral compaction could be demonstrated. As a rule, CSS are not approved for thermoplastic obturation, as these sealers are water-based; there is the concern that high temperatures of up to 200 °C will remove too much water from the sealer, which can have a negative impact on its properties. It is questionable whether such high temperatures are clinically achieved during thermoplastic obturation. A disadvantage of CSS is their higher solubility compared to epoxy resin sealers. In the long term, this can lead to the dissolution of the root canal filling. In the studies that have been performed to date, however, no difference in the clinical success rates between epoxy resin sealers and CSS has been determined. Overall, CSS represent an interesting alternative to conventional root canal sealers. In principle, the success of a root canal treatment depends not only on the obturation technique, but above all, on the complete removal of the infected tissue, the permanent disinfection of the root canal system and the bacteria-proof post-endodontic restoration. Keywords: calcium silicate, thermoplastic obturation, root canal filling techniques, root canal sealer