Characterization of cell adhesion phenomena at the dental abutment/soft tissue interface by means of a dynamic cell...

Effective cell adhesion under challenging mechanical situations is critical for a vital soft tissue sealing of the transmucosal parts of dental implants and thus essential for oral wound healing. To investigate this process in vitro, we developed a versatile flow chamber model that applies defined shear stress to assess the adhesion strength of relevant cell types. The system focuses mainly on primary human gingival fibroblasts, with preliminary experiments including also gingival keratinocytes. The chamber accommodates standard-sized titanium sample geometries used in projects dedicated to develop surface modifications preventing peri-implantitis. Actual shear stress was determined through computational fluid dynamics software, targeting a central 5 × 5 mm region used for cell seeding. Shear stress ranged from 0.05 Pa (0.4 ml/min) to 0.49 Pa (4 ml/min). Key variables studied included shear stress magnitude and duration of the dynamic phase. We assessed two titanium surface topographies-polished and nanodiamond-coated-to explore the role of nano-roughness in resisting detachment. Results demonstrated that topography significantly influences cell retention, with highest differences observed under 0.36 Pa shear stress for 1 to 2 h of dynamic phase. Furthermore, we adapted the model to simulate wound healing, revealing that surface topography impacts repopulation dynamics. Of two compared arrangements for the co-culture of fibroblasts and keratocytes, either sequential seeding of keratinocytes on top of pre-seeded fibroblast or simultaneously in adjacent regions, we prefer the latter approach for this specific dynamic model. Overall, in all model modifications the nanorough surfaces supported a more stable attachment of both fibroblasts and keratinocytes, with greater shear sensitivity of the keratinocytes. This model offers a reproducible, physiologically relevant platform to evaluate adhesion strength and wound healing, with potential for future application in biomaterial screening and implant design.