Periodontitis is a chronic inflammatory disease caused by microbial biofilms that leads to destruction of the periodontium, including the alveolar bone. Recent studies have revealed that periodontitis results from a breakdown of host-microbe homeostasis, leading to dysbiosis and inflammation. Keystone pathogens and pathobionts, which are commensal bacteria, play a key role in this process. These bacteria can manipulate the host immune response, leading to tissue destruction and a self-perpetuating cycle of inflammation and bone loss. The disease is influenced by both microbial and host factors, including genetic and environmental components. The immune response, particularly the role of Th17 cells and neutrophils, is crucial in the pathogenesis of periodontitis. Therapeutic strategies targeting host signaling pathways or inflammatory responses may offer new approaches for treatment. Understanding the complex interactions between the host and the microbiota is essential for developing effective interventions for periodontitis.Periodontitis is a chronic inflammatory disease caused by microbial biofilms that leads to destruction of the periodontium, including the alveolar bone. Recent studies have revealed that periodontitis results from a breakdown of host-microbe homeostasis, leading to dysbiosis and inflammation. Keystone pathogens and pathobionts, which are commensal bacteria, play a key role in this process. These bacteria can manipulate the host immune response, leading to tissue destruction and a self-perpetuating cycle of inflammation and bone loss. The disease is influenced by both microbial and host factors, including genetic and environmental components. The immune response, particularly the role of Th17 cells and neutrophils, is crucial in the pathogenesis of periodontitis. Therapeutic strategies targeting host signaling pathways or inflammatory responses may offer new approaches for treatment. Understanding the complex interactions between the host and the microbiota is essential for developing effective interventions for periodontitis.