Influence of different finishing and polishing protocols of composite CAD CAM blocks on surface roughness and biological response of gingival mesenchymal stem cells

Abstract

The surface quality of composite CAD/CAM restorations is vital in aesthetics, longevity, and the biological response of surrounding gingival tissues. Yet, little is known about how different finishing and polishing techniques influence cellular behavior at the tissue interface. This study aimed to evaluate how various finishing and polishing systems affect the surface roughness of composite CAD/CAM blocks, and how these differences influence the attachment, viability, and inflammatory response of gingival mesenchymal stem cells (GMSCs). Seventy-seven composite CAD/CAM specimens were prepared and subjected to one-step, two-step, and multi-step finishing/polishing protocols, with or without polishing paste. Surface roughness was measured using a digital profilometer. GMSCs were isolated from healthy donors, characterized, and cultured on the composite surfaces. Cell viability was assessed by MTT assay, adhesion was evaluated using scanning electron microscopy (SEM), and inflammation-related gene expression (IL-1β and TGF-β) was analyzed via q-PCR. Polished surfaces significantly reduced roughness and improved biological outcomes. Two-step finishing and polishing with paste resulted in the smoothest surfaces. GMSCs showed greater attachment and viability on polished composites, particularly in the two-step group. Inflammatory gene expression was lowest in polished groups, with IL-1β expression highest in unpolished specimens and TGF-β expression highest in the one-step groups. Finishing and polishing protocols directly impact the surface roughness as well as the biocompatibility of CAD/CAM composite surfaces. Smoother surfaces achieved through proper finishing and polishing enhance cell attachment and viability, and reduce inflammatory responses, highlighting the critical role of finishing in restorative success beyond aesthetics.