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

## TL;DR

New cement formulations with zirconium or strontium phosphate show good performance and could replace traditional dental cements.

## Contribution

The study introduces new calcium silicate-based cements with zirconium or strontium phosphate that meet or exceed industry standards without radiopacifiers.

## Key findings

- The new cements exceeded ISO radiopacity requirements without radiopacifiers.
- SPS formulation had a significantly longer final setting time compared to CZS.
- Both formulations showed sustained calcium/strontium ion release and maintained an alkaline pH.

## Abstract

What are the main findings?
The experimental cements exhibited adequate physicochemical performance.The radiopacity exceeded the ISO requirements without the need for radiopacifiers.The setting time improved compared with previous formulations.The solubility remained within acceptable limits.An alkaline pH and sustained calcium/strontium ion release were observed.

The experimental cements exhibited adequate physicochemical performance.

The radiopacity exceeded the ISO requirements without the need for radiopacifiers.

The setting time improved compared with previous formulations.

The solubility remained within acceptable limits.

An alkaline pH and sustained calcium/strontium ion release were observed.

What are the implications of the main findings?
Calcium silicate-based cements with zirconium or strontium phosphate may reduce the need for radiopacifiers.Formulations show potential as alternatives to commercial materials.The results support future biological and clinical investigations.

Calcium silicate-based cements with zirconium or strontium phosphate may reduce the need for radiopacifiers.

Formulations show potential as alternatives to commercial materials.

The results support future biological and clinical investigations.

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 (p < 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 (p > 0.05). Under these conditions, the experimental ERCs demonstrated adequate physicochemical performance comparable with commercial materials.