Restoration of the lost natural tooth by dental implants has modernized the practice of dentistry. Dental Implants have improved the lives of many patients,but implant associated infection remains a serious complication with significance morbidity and mortality. Periodontal diseases and peri-implant disease are specific infectious that are originating from these resident microbial species when the balance between the host and microbial pathogenicity gets disrupted.This article focuses on understanding peri-implant microbiology and its role in peri-implant diseases. Keywords: Bacterial Interaction, Plaque Development,Peri Implantitis ,Implant -Abutment Interface