Periodontal disease does not increase the risk of subsequent psoriasis

Previous studies suggested that chronic periodontitis may be a risk factor for psoriasis. However, no study has confirmed this relationship for all stages of periodontal disease (gingivitis and periodontitis). This nationwide population-based retrospective cohort study aimed to investigate whether periodontal disease is an independent risk factor for the development of subsequent psoriasis. Patients aged ≥ 20 years who underwent both medical and oral checkups from the National Health Screening Program between 2002 and 2007 were selected from a customized database provided by the National Health Insurance Service (NHIS). Then, patients with periodontal disease (n = 3,682,468) and without periodontal disease (control, n = 3,637,128) according to oral examination results were identified. We tracked each patient for subsequent psoriasis diagnosis until the end of 2018 using NHIS database. The incidence rates of psoriasis per 1000 person-years were 0.36 and 0.34 in the periodontal disease group and control groups, respectively. After adjusting for potential cofactors, no significant increase in risk (adjusted hazard ratio, 0.994; 95% confidence interval, 0.974–1.015) was observed. Similar results were observed when analyzing the risk of psoriasis in patients who required scaling or periodontal surgery. In conclusion, periodontal disease is not an independent risk factor of psoriasis.