Surface modifications of titanium dental implants: optimizing antibacterial activity and osteoimmunomodulation

Titanium (Ti) and its alloys are the gold standard for dental implants and orthopedics generally. This is mainly attributed to their exceptional mechanical properties, corrosion resistance and high biocompatibility. Regardless of their clinical success, Ti suffers from certain drawbacks including the slow osseointegration due to the bio-inertness of Ti, additionally, their surface is susceptible to bacterial adhesion leading to biofilm formation and then causing condition like peri-implantits and implant failure. For that, achieving a long-term successful implant requires addressing a dual challenge, mainly to achieve high tissue integration with limiting bacterial colonization. This review paper compiles the innovative strategies in Ti surface engineering for the past 15 years. Mainly, focusing on developing multifunctional implants that have high osseointegration capacity with antimicrobial properties. The review progress from discussing the conventional modification methods such as etching and grit blasting, to advanced physiochemical approaches, including nanoscale modification, biomimetic functionalization and stimuli responsive technologies. This review highlights strategies to integrate functional components by modifying surface topography, charge and wettability. For example, approaches like topographical modifications, inorganic and organic modifications are discussed. A considerable focus is addressed to the role of osteoimmunology, mainly on how surface modifications can modulate the host immune response by promoting the polarization of the anti-inflammatory M2 macrophages with dominance over the M1 type which induce inflammation. Further thing this review highlights is the advanced smart surface designs that respond to internal or external stimuli for on request release of drugs or antimicrobial agent activation. Finally, translational challenges are discussed including the need for long term clinical data, enhanced mechanical stability, and tracking of regulatory concerns regarding the nano-toxicity and ion release. Future directions are directed towards designing immune instructive and dynamically responsive implants that move beyond passive biocompatibility but toward active biological integration.