Periodontitis, Psoriasis and Other Skin Disorders: Epidemiological and Mechanistic Evidence.

Periodontitis is a highly prevalent chronic inflammatory disease characterized by a dysbiotic biofilm-induced host immune dysregulation and sustained low-grade systemic inflammation. Psoriasis and other inflammatory skin disorders, including atopic dermatitis and alopecia, are immune-mediated conditions driven by complex interactions between genetic susceptibility, environmental triggers, microbial factors, and cytokine network activation. Mounting epidemiological and experimental evidence suggests a consistent association between periodontitis and psoriasis, with emerging links to other skin disorders. This narrative review critically appraised the current available evidence regarding the epidemiological association between periodontitis and inflammatory skin disorders, explored the shared pathogenic mechanisms underpinning a potential oral-skin axis, and evaluated the impact of periodontal therapy on dermatological outcomes. Epidemiological and meta-analytical data suggest a positive association between periodontitis and psoriasis across diverse populations, although direct causality remains unclear. Mechanistically, overlapping pathways include systemic dissemination of pro-inflammatory cytokines (e.g., IL-6, TNF-α, IL-17), Th17-driven immune responses, neutrophil priming and NETosis, microbial translocation, and shared lifestyle-related determinants within the multimorbidity framework. Preclinical and clinical randomized controlled trials suggest that non-surgical periodontal therapy may reduce psoriasis severity and extent over the short term (8-10 weeks), potentially acting as a relevant adjunct to dermatologic medications. While heterogeneity and residual confounding limit definitive conclusions, the convergence of epidemiological, mechanistic, and interventional evidence supports the plausibility of a bidirectional interaction between periodontal and skin inflammation and the potential existence of an oral-skin axis. Interdisciplinary clinical strategies integrating periodontal and dermatologic care should be implemented for the early diagnosis and management of both periodontal and skin diseases and conditions.