Introduction: conventional nanohybrid (CeramX) and ormocer-based (Admira fusion) dental composite resins were compared investigating their effects on human dental pulp stem cells (hDPSCs) in terms of cytotoxicity, migration and osteogenic differentiation.

Methods: The samples and the eluates were prepared according to ISO 10993-12. hDPSCs were treated with different dilutions (undiluted, from 1:2 to 1:100) of CeramX and Admira fusion eluates. Viability assays were conducted in standard or osteogenic conditions using the MTT test. Furthermore, we analysed the migration activity with scratch test. Osteogenic differentiation potential was evaluated exclusively at dilution of 1:50 by Alkaline Phosphatase Activity and Alizarin Red Staining assay.

Results: Admira Fusion demonstrated to be highly biocompatible and positively influenced the proliferation of hDPSCs; on the contrary, CeramX showed to be more cytotoxic. The ormocer-based eluate exhibited osteo-inductive effects on hDPSCs when diluted at ratio of 1:50; conversely, conventional nanohybrid composite did not show any notable effect on stem cells differentiation.

Conclusions: The lower cytotoxicity observed with Admira Fusion compared to the conventional nanohybrid composite could be attributed to a reduced monomers release in the oral environment. This evidence supports the hypothesis of limited adverse effect and enhanced healing potential, particularly when the material is positioned in close contact with pulp tissue.