Peri-implant mucositis and peri-implantitis are clinically associated with inflammation of soft tissue around implants; however, peri-implantitis is associated with radiographic bone loss. Recently a new classification scheme—peri-implant health, peri-implant mucositis, peri-implantitis, and peri-implant soft-tissue and hard-tissue deficiencies—was introduced. Although various clinical interventions to treat peri-implant diseases have been suggested, early diagnosis and treatment is the key to successful outcomes. Clinicians can select nonsurgical or surgical techniques according to the clinical parameters present, although surgical intervention seems to be more effective in treating peri-implantitis. The best approach to treat peri-implantitis remains controversial.