Copper-Functionalized Titanium-Based Materials for Dental Applications: A Focused Narrative Review Linking Processing and Cu Exposure to Biological Responses and Application-Specific Design

Titanium and Ti-based alloys are widely used in dentistry, where their interfaces face chemical, microbial, mechanical, and tissue challenges. This focused narrative review considers endosseous and transmucosal implant interfaces, crowns, orthodontic wires and attachments, and guided bone regeneration/maxillofacial devices. Copper functionalization can provide antibacterial and antibiofilm activities; however, comparisons across studies are complicated by differences in the Cu state, surface architecture, release protocols, and biological models. Informed primarily by a targeted PubMed search and supplemented by materials science sources, this review examines how processing and surface engineering control Cu presentation and release and how these variables relate to antibacterial, soft-tissue, immune, and osteogenic responses. The nominal Cu content is a poor predictor of performance when phase morphology, passive-film behavior, surface topography and chemistry, aging, wear, and surrounding media differ. Antibacterial evidence is comparatively well developed, whereas soft-tissue data remain limited and heterogeneous. The evidence is synthesized within a conceptual, application-specific functional Cu exposure window: antibacterial efficacy informs the lower boundary, host-cell and inflammatory tolerance constrain the upper boundary, and corrosion, surface stability, and Cu depletion determine persistence. However, this framework does not establish a validated or transferable numerical range for Cu. Progress will require matching materials and electrochemical, release, and biological measurements under application-relevant oral conditions.