The development of bioactive materials in endodontics has advanced tissue regeneration by enhancing the biological responses of periradicular tissues. Recently, calcium silicate-based sealers have gained attention for their superior biological properties, including biocompatibility, osteoconductivity, and cementogenic potential. This study aimed to evaluate the cytotoxicity, biocompatibility, and bioactivity of EndoSequence BC Sealer (ES BC) and AH Plus Bioceramic Sealer (AHP BC) using human periodontal ligament stromal cells (hPDLSCs). Biocompatibility was assessed using MTT, Live/Dead, and wound healing assays. ES BC and AHP BC demonstrated significantly higher cell viability and proliferation compared to AH Plus used as a control. Gene expression analysis via real-time quantitative PCR demonstrated that ES BC, especially in set form, significantly upregulated osteogenic markers-alkaline phosphatase (2.49 ± 0.10, p < 0.01), runt-related transcription factor 2 (2.33 ± 0.13), and collagen type I alpha 1 chain (2.85 ± 0.40, p < 0.001)-more than cementogenic markers (cementum protein 1, cementum attachment protein, and cementum protein 23). This differential response may reflect the fibroblast-dominant nature of hPDLSCs, which contain limited cementoblast-like cells. This study supports the superior biocompatibility and regenerative capacity of ES BC and AHP BC compared to AH Plus. While in vitro models provide foundational insights, advanced ex vivo approaches are crucial for translating findings to clinical practice.