Periodontium is influenced by various systemic, environmental, and psychologic factors that have the potential to alter periodontal tissues and host immune response, resulting in more severe periodontal destruction.With bacterial plaque being the primary etiological factor,host and environmental factors also play an important role in disease progression and severity . Psychosocial stress can affect the periodontal tissues directly through biological mechanism(emphasizes how stress and depression can reduce immune system function) and indirectly through the changes in life-style such as ignoring oral-hygiene measures, smoking more heavily and consuming more fat and sugar in diet.This dissertation reviews how stress effects the periodontium and how it modifies the progression and outcome of periodontal disease.