Background:
Biofilm-related complications remain common in full-arch implant-supported prostheses. Although zirconia is considered relatively biofilm-resistant, complex intaglio surface geometry may create protected microbial niches.

Objective:
To evaluate the association between intaglio surface geometry, biofilm accumulation, and Candida colonization in full-arch implant-supported prostheses.

Methods:
Prostheses in function for ≥12 months were removed, disclosed, and digitally analyzed for biofilm coverage. Biofilm samples were cultured to detect Candida. Bacterial and fungal loads were analyzed at prosthesis and patient levels.

Results & Conclusions:
Bacterial loads exceeded fungal loads across both arches. Candida colonization was heterogeneous and not arch-dependent, suggesting microbial ecology is driven by localized prosthetic microenvironments rather than plaque quantity.

Keywords: full-arch implant prosthesis; intaglio surface; biofilm; Candida albicans; zirconia; PMMA; peri-implant mucositis; peri-implantitis