Titanium as Dental Implant Material: Introduction -- Implants in Compromised Conditions: Need for Bioactivity and Therapy -- Surface Modification: Macro- and Micro-Scales -- Nano-Scale Surface Modification: Fabrication -- Nano-Scale Surface Modification: Local Therapy -- Nano-Scale Surface Modification: Enhanced Bioactivity -- Mechanical Stability of Titanium Dental Implants -- Corrosion and Electrochemical Stability -- Cytotoxicity Evaluations -- Research Gaps and Future Directions.