Piezoelectric materials for surface modification of titanium-based implants: material design, biological mechanisms, and translational challenges.

Titanium and its alloys are widely used in orthopedic and dental implants and bone repair scaffolds because of their mechanical properties, corrosion resistance, and biocompatibility. However, their bioinert surfaces may still show poor early osseointegration, bacterial infection, inflammatory imbalance, and limited long-term interfacial stability. Conventional surface modifications mainly change topography and chemistry, but provide limited simulation of the bone electrophysiological microenvironment. Piezoelectric materials convert physiological loading or external ultrasound into local electrical signals, offering a route to dynamically responsive titanium interfaces. This review summarizes piezoelectric material types, coating design, preparation methods, and biological effects on titanium surfaces. It discusses mechanisms related to osteogenic differentiation, osseointegration, antibacterial effects, infection control, and osteoimmune regulation. Piezoelectric coatings may affect membrane potential, ion channels, the cytoskeleton, cell adhesion, reactive oxygen species production, and macrophage function. Key translational challenges include signal decay in wet conditions, weak interfacial bonding, limited long-term stability, material safety concerns, lack of standardized preparation, and insufficient