In vitro evaluation of pH, calcium ion release and interfacial characterization of calcium silicate–based and epoxy resin–based sealers

Abstract

This in vitro study evaluated the physicochemical properties and interfacial behavior of four calcium silicate–based sealers (CSBS) compared to an epoxy resin–based sealer. Specimens were prepared under standardized conditions, and pH and calcium (Ca 2+ ) ion release were measured over time. The interfacial characterization was performed on selected extracted teeth using scanning electron microscopy to evaluate gap formation and energy-dispersive X-ray spectroscopy to determine elemental composition. Statistical analysis included linear mixed-effects models for repeated pH and interfacial gap measurements, one- and two-way ANOVA with Tukey’s HSD post hoc test, and Kruskal–Wallis test with Dunn’s post hoc test, with statistical significance set at p  < 0.05. All CSBS exhibited consistently high alkaline pH values and measurable calcium ion release, whereas the epoxy resin–based sealer showed neutral pH and no detectable Ca 2+ release. Interfacial analysis revealed higher Calcium-to-Phosphorus (Ca/P) ratios and lower relative calcium differences for CSBS, whereas the resin-based sealer showed greater differences in calcium and carbon content at the dentine–sealer interface. Additionally, interfacial gap width differed according to sealer type and canal region, with CSBS generally showing smaller SEM-measured gaps than AH Plus and gap widths tending to increase toward the apical region. CSBS demonstrated higher alkalinity, measurable calcium ion release, and generally favorable interfacial adaptation compared with the epoxy resin–based sealer. The observed alkaline pH, calcium ion release, and favorable interfacial adaptation highlight physicochemical and interfacial characteristics that are relevant when considering CSBS for root canal obturation.