Evaluation of Cytotoxicity and Osteogenic Potential of Strontium Silicate and Calcium Silicate-Based Sealers

This study aimed to evaluate the cytotoxicity and osteogenic potential of three sealers, including a strontium silicate-based sealer, C-Root SP (C-R), and two calcium silicate-based sealers, iRoot SP (i-R) and AH Plus Bioceramic Sealer (AHPbcs), compared with AH Plus (AHP) on MC3T3-E1 pre-osteoblasts.

Standardized sealer discs were eluted in a culture medium to assess cytotoxicity using the CCK-8 assay at various dilutions (1:1, 1:2, 1:5, and 1:10). Osteogenic differentiation was evaluated by culturing cells in osteogenic medium supplemented with 1:5 diluted sealer extract. Alkaline phosphatase (ALP) activity was assessed with an ALP assay and staining on days 7 and 14. Mineralized nodule formation was observed using Alizarin Red S staining on day 21. Gene expression of osteogenic markers (ALP, COL1A1, and RUNX2) was examined by RT-qPCR. Differences were analysed using one-way/two-way variance analysis with the Tukey post-hoc test. Statistical significance was established at P < .05.

C-R, i-R, and AHPbcs showed significantly higher cell viability than AHP (P < .001). All sealers exhibited cytotoxicity at higher concentrations (1:1 and 1:2 dilutions). ALP activity was significantly lower in cells exposed to AHP compared to cells exposed to C-R, i-R, and AHPbcs (P < .01). Cells exposed to C-R, i-R, and AHPbcs exhibited higher mineralized nodule formation than cells exposed to AHP. C-R, i-R, and AHPbcs enhanced osteogenic differentiation with higher osteogenic gene expression than AHP (P < .001).

Within the limitations of the study, C-R, i-R, and AHPbcs were biocompatible with MC3T3-E1 pre-osteoblasts at lower concentrations and were able to enhance their osteogenic potentials.

The strontium silicate-based sealer shows a favourable biological response and osteogenic activity in vitro, comparable to calcium silicate-based sealers, indicating its potential for clinical applications.