Titanium Anodization for Dental Implant Surface Engineering: A Critical Narrative Review of Process–Structure–Property–Function Relationships

Titanium anodization enables the formation of TiO2 nanotube (TNT) architectures with structural, physicochemical, mechanical, electrochemical, and biological characteristics relevant to dental implant surface engineering. This critical narrative review, complemented by bibliometric analysis, integrates two methodologically distinct evidence streams: a predefined Scopus dataset used exclusively for quantitative bibliometric analysis and a critical narrative synthesis based on relevant Scopus-indexed literature and supported by supplementary PubMed/MEDLINE searches. Using a Process–Structure–Property–Function (PSPF) framework, the review examines how anodization conditions and substrate characteristics determine TNT architecture and how the resulting structural state influences surface properties and biological function. The available evidence demonstrates substantial interdependence among processing variables and does not support universally optimal TNT dimensions or anodization parameters; rather, functional outcomes depend on system-specific processing windows, the combined surface state, and the intended application. Multifunctional and stimuli-responsive TNT systems, additive manufacturing combined with anodization, fluoride-free processing, and data-assisted optimization offer emerging opportunities but remain predominantly experimental or preclinical. Translation is constrained by methodological heterogeneity, limited standardization, and insufficient validation through sterilization, storage, implant insertion, and long-term exposure. Direct clinical validation of well-defined self-organized TNT architectures on dental implants is currently lacking, with the available evidence derived predominantly from in vitro and preclinical studies. Future development should prioritize reproducible processing windows, standardized characterization, validation on final implant geometries, and quantitative linkage of processing conditions to structure, properties, biological function, and long-term clinical performance.