The evolution of implant dentistry has transformed the rehabilitation of edentulous patients, enabling the delivery of prosthetic restorations that combine exceptional function, durability, and esthetics. However, as implant-supported prostheses become increasingly routine in clinical practice, the management of complications has emerged as a pivotal determinant of long-term success. This chapter provides a comprehensive and evidence-based overview of the mechanical, biological, and prosthodontic complications associated with implant-supported restorations. Biomechanical failures—including screw loosening, component fracture, and framework misfit—are analyzed in the context of load distribution, prosthetic design, and material selection. Biological complications such as peri-implant mucositis, peri-implantitis, and early osseointegration failure are examined with emphasis on etiology, diagnostic criteria, and preventive strategies. Additionally, esthetic and patient-centered complications are discussed, underscoring the importance of expectation management, digital diagnostics, and trial restorations in achieving satisfactory clinical outcomes. The chapter concludes with practical guidelines aimed at reducing the incidence of complications through meticulous treatment planning, adherence to biomechanical principles, and a holistic understanding of the implant–tissue interface. By integrating these insights, clinicians can enhance the predictability, longevity, and patient satisfaction associated with implant-supported dental prostheses.