Modified Formulations of Silicate-Based Cements: Comparative Study of Physicochemical Properties

This study aimed to prepare experimental calcium silicate repair cements (ERCs) incorporating zirconium (Ca₃ZrSi₂O₉; CZS) or strontium substitution (Sr₅(PO₄)₂SiO₄; SPS), and to compare their physicochemical properties with white MTA-Angelus (WMTA), grey MTA-Angelus (GMTA), and Biodentine (BD). After synthesizing the CZS and SPS phases, powder-liquid cements were formulated. The setting time and radiopacity were assessed according to ISO 6876/12 and ASTM C266, the volumetric solubility by micro-CT, the pH by a pH meter, and the calcium/strontium ion release by FAAS/ICP-OES. Data were analyzed using ANOVA and Tukey's tests (5%). The initial setting time was 11 min for SPS and 6 min for CZS (<i>p</i> < 0.05), while the final setting was significantly longer for SPS (49 min). Both ERCs showed radiopacity above the 3.0 mm Al minimum, with higher values for CZS (4.58 mm Al). The solubility remained controlled, with CZS presenting the highest value (3.09%). Both materials exhibited an alkaline pH, peaking at 24 h (CZS: 9.70; SPS: 10.04) and decreasing until 168 h (CZS: 7.80; SPS: 8.31). Sustained ionic release was observed: CZS showed intermediate calcium release (25.96 mg/L at 3 h), whereas SPS displayed lower values (10.95 mg/L at 168 h), without significant difference from WMTA (<i>p</i> > 0.05). Under these conditions, the experimental ERCs demonstrated adequate physicochemical performance comparable with commercial materials.