The Fate of Apically Extruded Sealers: Radiographical Disappearance or Biological Integration? A Narrative Review

Objective: Over the past 2 decades, several novel materials have been introduced into endodontic practice, specifically designed to be bioactive and biointeractive with apical bone tissues. However, despite their widespread adoption, there remains limited consensus on the biological consequences of accidental apical extrusion, particularly when premixed bioceramic sealers are used. This review aims to analyse both the immediate and long-term effects of apical extrusion of new bioactive root canal sealers compared to traditional bioinert obturation materials. Methods: Open search strategy was performed on indexed public databases (Scopus, PubMed, Embase). Data were gathered from clinical reports, in vivo animal studies, and in vitro experiments that investigated clinical outcomes, apical healing, occurrence of post-operative pain, occurrence of apical extrusion as well as tissue responses, inflammatory potential, and sealer resorption. Results: The review highlights variations in the biological behaviour depending on different sealer formulations and their interaction with periapical tissues. Apical extrusions of biologically active sealers such as premixed bioceramic sealers may result in dynamic radiographical modifications during the follow-up. This behaviour has also been observed in minor percentages for traditional zinc oxide sealers, in similar percentages for calcium hydroxide-based sealers. No modifications of apical extruded sealer were observed for epoxy resin-based sealers. Conclusion: The extrusion of any endodontic material beyond the apical foramen continues to pose potential risks, particularly in the presence of pre-existing periapical pathologies. For clinicians, it is important to understand the properties and composition of each sealer. There is a need for further long-term high-quality clinical trials to establish the long-term impact of sealers' radiographical disappearance when extruded into periapical issues. Establishment of a standardised terminology to accurately describe these phenomena and to prevent misinterpretation or inconsistency in future investigations is also recommended.