Physicochemical stability of contemporary endodontic sealers with distinct chemical bases under thermal stress: a multi-analytical approach

The aim of this study was to evaluate the physicochemical stability and clinical handling properties of contemporary root canal sealers with different chemical bases (hydraulic calcium silicate, resin, and silicone-based) under thermal stress simulating warm vertical compaction (WVC) using a multi-analytical approach. Total Fill BC Sealer HiFlow, Edge Bioceramic, BioRoot RCS, GuttaFlow Bioseal, AH Plus Bioceramic, MTA Fillapex and AH Plus were evaluated. Structural, chemical, and thermal characterization of the sealers were performed using SEM, EDS, FTIR, XRD, and DSC analyses. Samples were exposed to physiological body temperature (37 °C, control group) or thermal stress simulating the heat produced during WVC (100 °C). Setting time, flow, film thickness, water sorption, solubility, and pH were assessed according to ISO standards. Heat application significantly reduced the setting time in all materials (p < .05), with the greatest reductions observed in BioRoot RCS and Edge Bioceramic Sealer. Following heat exposure, flow values decreased significantly in BioRoot RCS, GuttaFlow Bioseal, and AH Plus Bioceramic (p < .05), rendering these specific materials non-compliant with ISO 6876 requirements. In contrast, Total Fill BC Sealer HiFlow and AH Plus showed no significant changes in flow (p > .05). Film thickness significantly increased in BioRoot RCS, Edge Bioceramic Sealer, Total Fill BC Sealer HiFlow, and AH Plus and after heating (p < .05). Conversely, AH Plus Bioceramic and MTA Fillapex demonstrated stability with no significant changes in film thickness (p > .05). Heat application did not significantly affect pH values at any time point (p > .05). Thermal stress simulating WVC induces material-dependent physicochemical changes in contemporary root canal sealers. Sealers relying on aqueous hydration mechanisms are particularly susceptible to heat-induced instability, whereas premixed calcium silicate sealers engineered for warm obturation and epoxy resin-based sealers demonstrate superior thermal stability. The multi-analytical characterization proved pivotal in elucidating the underlying mechanisms, linking the physical stability to dehydration and phase transitions.