Endodontic sealers based on calcium silicates: a systematic review

Recently, sealers based on calcium silicates were developed as a new class of endodontic sealers. Inspired by the excellent sealing ability and biocompatibility of calcium silicate-based cements, these sealers establish a biological point of view on the obturation of root canals. No longer, the bacteria-tight seal against reinfection of the root canal is the only goal of root canal obturation. Antibacterial properties as well as bioactive inducement of periapical healing and hard tissue formation are added to the portfolio of sealers. Ready-to-use sealers consisting of only one component with a need for external water supply from, e.g., body fluid and two components sealers with internal water supply were introduced to the market. Both of these material types have the same setting reactions in common whereby a hydration reaction of the calcium silicate is followed by a precipitation reaction of calcium phosphate. Though the available sealers are all based on calcium silicates, they consist of different compositions. Due to this aspect, differences in their physical and chemical properties as well as in their in vitro characteristics were described. Studies addressing the clinical impact of calcium silicate-based sealers on outcome are still sparse. The bioactive potential of sealers based on calcium silicates is a consequence of the slight solubility of these materials even after setting, but solubility of the sealer might also compromise the quality of sealing a root canal against regrowth and reinfection. Further clinical investigations are required to evaluate the clinical relevance of the gulf between bioactivity and solubility.