Volumetric Stability and Interfacial Adaptation of Tricalcium Silicate-Based Cements Used in the Lid Technique: A Micro-Computed Tomography and Scanning Electron Microscopy Analysis

INTRODUCTION: This in vitro study evaluated the volumetric stability and interfacial adaptation of tricalcium silicate-based cements with different consistencies (sealer and putty) applied using the Lid technique for retrograde filling in apical surgery. METHODS: Thirty bovine incisors were prepared, obturated, and apically resected to create standardized 3 mm retrograde cavities. Specimens were randomly allocated to three groups (n = 10): BioRoot Flow + BioRoot RCS, EndoSequence BC Sealer + EndoSequence RRM, and Bio-C Sealer + Bio-C Repair. Flowable sealers were injected into the retrocavities, followed by placement of a putty layer. Micro-computed tomography scans were obtained at baseline (D0) and after 30 days of immersion in phosphate-buffered saline (pH 7.4, 37 °C). Volumetric changes over time were analyzed using one-way and repeated measures ANOVA with Tukey post hoc tests for intergroup and intragroup comparisons (α = 0.05). Selected specimens underwent scanning electron microscopy for qualitative evaluation of interfacial adaptation. RESULTS: All materials exhibited minimal volumetric change after 30 days ( .05). Scanning electron microscopy analysis demonstrated close adaptation to dentinal walls, continuous interfaces between sealer and putty layers, and penetration of sealers into dentinal tubules. Occasional microgaps were observed but did not compromise overall interfacial continuity. CONCLUSIONS: The Lid technique using tricalcium silicate-based sealers and putties maintained volumetric stability and demonstrated favorable interfacial adaptation under simulated physiological conditions. These findings support the structural compatibility of combining materials with different consistencies and suggest that this approach represents a feasible option for retrograde filling in apical surgery.