Anodized anisotropic titanium surfaces for enhanced guidance of gingival fibroblasts

Abstract

Ensuring the formation of a robust trans-mucosal soft-tissue seal at the dental abutment surface is crucial towards protecting the underlying dental implant associated tissues from the external microbial-rich oral environment. The ability to mechanically enhance fibroblast functions at the dental abutment-mucosa interface, without the use of bioactive agents, holds great promise towards reducing the ingress of oral pathogens into the dental implant microenvironment. We hereby propose fabrication of unique anisotropic titania nanopores (TNPs) on the surface of titanium (via electrochemical anodization, EA) towards enhancing the soft-tissue integration and wound healing abilities of the conventional abutments. Using optimized EA, mechanically robust TNPs of varied diameters were fabricated on Ti surfaces with preserved underlying substrate micro-features: dual micro-nanostructured surfaces. Next, we evaluated the mechanical stability of such structures and demonstrated the ease of fabrication on commercial abutment geometries. The functions of primary human gingival fibroblasts (GFs) cultured on these surfaces in vitro were evaluated from 1 h to 7 days, and were compared between TNPs and clinically relevant titanium controls: as-received irregular rough Ti (Rough Ti) and mechanically prepared micro-rough Ti (Micro Ti). Improved cell viability was observed on TNPs as compared to controls. Additionally, cellular spreading morphology indicated cell alignment along the direction of the nanopores with strong anchoring evident by enhanced filopodia and stress fibers. RT-PCR showed improved wound healing, cell migration/adhesion and angiogenesis related mRNA, especially for TNPs with large diameters. This study provides a proof-of-concept towards using anodization for improving soft-tissue sealing around dental abutment surfaces, with implications towards reducing implant failure/peri-implantitis and achieving long-term success, especially in compromised patient conditions.

Keywords: Anodization; Cell alignment; Dental implants; Fibroblasts; Soft-tissue integration; Titanium.