Building a better gingival seal in dental implants: hydrothermal ion incorporation into titanium abutment surfaces

Despite the recognised biocompatibility of grade V titanium (Ti-6Al-4 V), dental implant abutments have limited affinity for connective tissue, compromising the gingival seal and increasing infection risk. Improving the abutment-tissue seal remains a key challenge. In this study, anodised titanium V surfaces were modified via hydrothermal treatment to incorporate divalent metal ions (Mg²⁺, Zn²⁺, Mn²⁺, Cu²⁺ and Sr²⁺). Untreated anodised surfaces (YA) served as controls. The effects of these ion functionalised surfaces were evaluated using Human Gingival Fibroblasts (HGFs) and THP-1 macrophages. Parameters critical for gingival sealing (cell adhesion, collagen secretion, cytokine production) were scrutinised. Serum protein adsorption (proteomics) and antibacterial activity against Streptococcus gordonii were also investigated. Ion incorporation enhanced fibroblast adhesion, and Mg²⁺, Zn²⁺, Cu²⁺ and Sr²⁺ promoted collagen secretion, with Sr²⁺ showing the strongest effect. Surfaces enriched with Cu²⁺ also modulated the immune response, improving inflammatory control. Strontium and copper decreased immunoglobulin adsorption, suggesting a potential to reduce immune responses and improve connective tissue integration. This work provides, for the first time, a comparative evaluation of surfaces modified with these bioactive ions in an in vitro model representative of gingival connective tissue, together with proteomic and bacteria response analysis focused in S. gordonii.