In Vitro Evaluation of Periodontal Fibroblast Response to Bioinspired Porous Channel-Embedded Zirconia Surfaces

Customized implant approaches are emerging to meet specific patient needs while minimizing complications. Despite advances in osseointegrated implants, issues such as excessive bone loading, bacterial infiltration, peri-implantitis, and bone loss persist. Bioinspired designs with customized geometries and surfaces that promote fibrointegration, inspired by the periodontal ligament of a natural tooth, are increasingly recognized as a promising strategy. This study aimed to evaluate the ability of bioinspired zirconia surfaces to promote adhesion and guide the orientation of human periodontal ligament fibroblasts (hPLFs). Zirconia specimens with internal microchannels and an external porous coating were designed to mimic dentinal tubules and cementum-like features. Fabrication was performed using CAD/CAM CNC milling, followed by dip coating with zirconia suspensions. Microstructural characterization was carried out using scanning electron microscopy (SEM). hPLFs were cultured on the surfaces under a medium gradient (2% vs. 10% FBS) to induce migration from the porous exterior toward the channeled interior. Electrical impedance spectroscopy (1-100 kHz, Gamry system) was used to complement cell viability results and to better understand fibroblast behavior, considering the combined contributions of the cell layer, the culture medium, and the electrode-electrolyte interface. Specimens with 322 ± 7.86 μm channels and porous coatings (167.04 ± 51.87 μm thickness, 9% porosity) were produced. All were biocompatible, with the highest proliferation observed on specimens combining channels and porosity. SEM analysis revealed fibroblasts embedded within the porous layer, with spindle-like extensions anchoring and extending toward channels. Channel-porous specimens also exhibited the highest impedance after 3 days, suggesting enhanced attachment, migration, and spreading. These findings indicate that channel-porous zirconia surfaces enhance fibroblast adhesion and spreading in vitro, supporting their potential to guide structured cell organization. This bioinspired design represents an initial proof of concept for improving soft tissue interactions at the implant interface, paving the way for future fibrointegrative implant concepts such as root-analogue dental implants.