Tissue response, antimicrobial activity, and mechanical properties of calcium silicate cement prototypes for vital pulp therapies

The use of hydraulic calcium silicate cements (HCSCs) is essential for vital pulp therapies (VPT). However, their high cost restricts access in low- and middle-income countries, preventing the widespread benefits of VPT. This study aimed to evaluate four previously developed and characterized low-cost HCSC prototypes by examining their biological properties, specifically the rat connective tissue response after implantation and antimicrobial activity against five strains of interest. Additionally, their compressive strength, bond strength, and microhardness, which are critical mechanical properties of materials used in VPT, were assessed. All HCSCs caused an inflammatory reaction, which decreased over time in all cases, with most reactions categorized as mild. When comparing the number of inflammatory cells at each time point, no significant differences were observed between the HCSCs and those compared to MTA Angelus. Regarding the fibrous capsule, its thickness gradually decreased, and all capsules ultimately had a thickness with no significant difference compared to those formed in the empty control group. No significant differences in antimicrobial activity were seen among the four prototypes, as they exhibited similar performance against the five tested strains. However, some prototypes showed significantly better performance compared to MTA Angelus. Concerning mechanical properties, most prototypes exhibited substantially higher compressive strength than MTA Angelus, with a gradual increase over time-though this increase was not always significant. Additionally, no prototype demonstrated significant differences in bond strength compared to each other or MTA Angelus. Microhardness also increased over time, with significant differences observed when comparing prototypes to MTA Angelus at each time point. These findings, along with previously reported data on their microstructure, composition, and physical properties, support the potential clinical use of these prototypes. However, further research is needed to evaluate their effectiveness in clinical settings.