## 1 Introduction  
Endodontic obturation is an essential step in endodontic treatment; it is aimed at sealing the root canal system, preventing future bacterial contamination or recontamination [1]. For the success of endodontic treatment, it is important to achieve a filling that fully occupies the anatomy of the instrumented root canal. In this sense, the obturation of the lateral and/or accessory canals could play a significant role [2]. The presence of lateral canals represents a two-way path between the root canal and the periradicular tissues, which facilitates the passage of bacteria and their products [3]. Lateral canals are formed by the entrapment of periodontal vessels in [PERSON]'s epithelial sheath during root calcification [4]. The root canal system presents a complex anatomy, in which a significant percentage of lateral and/or accessory canals are observed, distributed according to the different root zones. [PERSON] et al. [5] found 27.4% of lateral canals with a distribution of 17% in the apical third, 8.8% in the middle and 1.6% in the coronary. The most common root canal obturing material is gutta-percha (GP), used in conjunction with various sealers. Different bioactive root canal sealers with regenerative properties have been introduced to the market. GuttaFlow(r) bioseal (GFB) (Coltene/Whaledent GmbH, Alstatten, Switzerland) is composed of gutta-percha powder, polydimethylsiloxane, platinum catalyst, zirconium dioxide, and bioactive glass ceramic. GFB was developed to improve the bioactivity of GuttaFlow(r), favoring the regeneration of the apical tissues [6]. GFB is a hydrophilic sealant that has shown low solubility and porosity, alkalizing ability, and penetrability of dentin [7] being also cytocompatibility [8]. Accordingto [PERSON] et al. [9], GFB has physicochemical properties appropriate to ISO and ADA (American Dental Association) standards, in terms of setting time, radiopacity, solubility at 7 and 30 days, and fluidity and volumetric change at 7 and 30 days. According to [PERSON] et al. [10], GuttaFlow(r) bioseal proved to be a promising endodontic material used in teeth with a broad (apical diameter 40) and wet apex, thanks to the incorporation of a calcium silicate component. However, the low calcium release evaluated limits its adoption in conditions in which an apical barrier formation is required. Bioceramics used in endodontics can be categorized by composition, setting mechanism, and consistency, and they are all hydrophilic. Bioceramic sealers have remarkable properties in terms of biocompatibility and antimicrobial activity with excellent bioactivity, capable of inducing mineralization of the periapical tissues [11; 12; 13]. Due to their hydrophilicity, they can set in a humid environment such as dentin, which is made up of almost 20% water [14]. BioRoot(r) RCS (Septodont, Saint Maur-des-Fosses, France) is an endodontic sealer with tricalcium silicate materials that benefit from the Active Biosilicate Technology and Biodentine(r) platform. Thanks to the use of Active BioSilicate technology, which is free of monomers, there is no shrinkage of BioRoot(r) RCS during setting to allow a high root canal seal. BioRoot(r) RCS is bioactive by stimulating the physiological formation of bone and mineralization of the dentin structure [15; 16]. Thus, it creates a favorable environment for periapical healing and bioactive properties including biocompatibility [17], hydroxyapatite formation, mineralization of the dentin structure, alkaline pH [18], and sealing properties. BioRoot(r) RCS is indicated for permanent root canal filling in combination with gutta-percha points and is suitable for use in single taper or cold lateral condensation techniques [19]. The use of biocearamic sealers is associated with single-cone filling techniques and not with vertical condensation with continuous wave, because heat interferes with their characteristics. Some authors have observed that gutta-percha thermoplastification affects the total obturation volume, creating fewer voids and gaps [20; 21; 22].