ORCID

Abstract

Dental implants are susceptible to bacterial colonisation, which can initiate peri-implant inflammation and ultimately lead to peri-implantitis and implant failure. Antimicrobial surface modifications represent a promising strategy to mitigate bacterial infection however, such approaches must preserve biocompatibility with peri-implant soft tissue cells to ensure effective mucosal sealing and long-term implant success. In particular, human gingival fibroblasts (HGFs) play a critical role in soft tissue integration at the implant-abutment interface, yet their interactions with antimicrobial silver-based coatings remain insufficiently understood. This thesis investigates the biocompatibility of nano silver-hydroxyapatite (Ag+nHA) coatings deposited on titanium substrates, with the aim of developing an antimicrobial yet soft tissue-compatible implant surface. Nanosilver was incorporated to impart antimicrobial functionality, while hydroxyapatite was introduced to modulate silver release and enhance cellular compatibility. Titanium discs were coated with nanosilver followed by either nano-scale or micro-scale hydroxyapatite deposition to produce Ag+nHA and Ag+mHA coatings, respectively. Uncoated titanium and silver-only coatings were used as material controls. Coating morphology, composition, and surface characteristics were assessed using microscopy and surface analytical techniques. The chemical stability of the coatings and silver release behaviour were evaluated through preconditioning, dialysis, and dissolution experiments in biologically relevant media. The biological response of HGFs to the coatings was investigated using both two-dimensional culture and three-dimensional collagen gel models to better replicate the peri-implant soft tissue environment. Cell viability, metabolic activity, membrane integrity, morphology, extracellular matrix production, and electrolyte homeostasis were assessed over a 7-day culture period using biochemical assays, microscopy and elemental analysis. The results demonstrated that all coatings were successfully fabricated and remained chemically stable in culture conditions, exhibiting controlled silver release over time. While silver-containing surfaces initially reduced fibroblast metabolic activity, Ag+nHA coatings supported significantly improved cellular recovery, morphology and viability compared with silver-only and Ag+mHA coatings. Importantly, electrolyte profiles in both culture media and cell homogenates remained within physiologically relevant ranges, indicating preserved ionic homeostasis and the absence of overt cellular stress. Three-dimensional collagen gel studies further confirmed healthy fibroblast distribution, matrix interaction, and gel integrity across all surfaces, with Ag+nHA demonstrating the most favourable overall cellular response. This thesis demonstrates that the incorporation of nano-scale hydroxyapatite onto nanosilver-coated titanium surfaces significantly enhances biocompatibility with human gingival fibroblasts while maintaining controlled silver release. These findings provide mechanistic insight into soft tissue-material interactions at the implant interface and supports the potential of Ag+nHA coatings for improving peri-implant soft tissue integration and reducing the risk of peri-implantitis.

Awarding Institution(s)

University of Plymouth

Award Sponsors

Engineering and Physical Sciences Research Council

Supervisor

Alexander Besinis, Richard Handy, Vehid Salih, Christopher Tredwin

Keywords

Nano-silver, Biocompatibility, Nanocoating, Peri-implantitis, Gingival fibroblast

Document Type

Thesis

Publication Date

2026

Embargo Period

2026-06-23

Deposit Date

June 2026

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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