Psychosocial stress plays an important role in periodontal disease through biological and behavioral pathways. In this paper we review studies that examine the relationship between stress and periodontal diseases, and discuss the different measures used to assess stress. Self-reported measures, such as the Perceived Stress Scale and the Stress Appraisal Measure, have traditionally been used to assess stress. Frequent and repeated exposure to stressor(s) leads to wear and tear of the body's systems, resulting in what is known as allostatic load. In recent years, few studies examining the relationship between stress and periodontal diseases have used an aggregate variable, including primary and secondary markers of allostatic load, as a biological marker of stress. While research on the relationship between allostatic load and periodontal disease is still developing, as most of the studies used cross-sectional data, this line of research presents a good opportunity for establishing a composite biological indicator as a risk factor for periodontal disease. Such an indicator is also potentially beneficial for personalized periodontics as it will help to target intervention to specific levels of risk and will help in integrating oral and general health promotion policies.