Effects of Periodontal Therapy on Psoriasis Severity: A Systematic Review of the Clinical Evidence

Background: Periodontitis and psoriasis are chronic inflammatory diseases that share common risk factors and immune-mediated pathogenic pathways, suggesting a potential bidirectional relationship. Periodontal inflammation contributes to systemic inflammatory burden, which may influence the severity of immune-mediated diseases, such as psoriasis. Objective: The aim of this systematic review is to evaluate the effects of periodontal therapy on psoriasis severity in patients affected by both conditions. Methods: This review followed the PRISMA 2020 guidelines and was registered in PROSPERO (CRD420251155439). Eligible studies included adults (≥18 years) with both psoriasis and periodontitis undergoing periodontal therapy compared with no periodontal treatment. The primary outcome was Psoriasis Area and Severity Index (PASI), while secondary outcomes included periodontal clinical parameters (PPD, CAL, FMBS). Results: A total of 228 records were identified; after screening and full-text evaluation, two randomized controlled trials, including a total of 166 patients, met the inclusion criteria. Both studies evaluated non-surgical periodontal therapy and reported significant reductions in PASI scores in treated patients compared with controls. Periodontal parameters (PPD, CAL, FMBS) also improved significantly following treatment in both studies. Conclusions: Evidence from the included trials indicates that non-surgical periodontal therapy may reduce psoriasis severity while simultaneously improving periodontal health in patients with both conditions. Periodontal treatment may serve as a beneficial adjunct to dermatological therapy. However, findings are limited by small sample sizes and short follow-up periods. Larger, long-term randomized controlled trials are needed to confirm these results.