AIM: To assess the impact of non-surgical periodontitis treatment over conventional dermatological treatment on the severity and extent of psoriasis in patients affected by comorbid psoriasis and periodontitis. METHODS: Seventy-four patients affected by both psoriasis and Stages I-IV periodontitis were randomized to receive either Steps 1-2 (non-surgical) of periodontal therapy (test group
n = 37) or no treatment (control group
n = 37). The two groups were balanced in terms of psoriasis medications, with the majority of the included patients undergoing biologics (74.0%) as monotherapy, while minor proportions were under systemic medications (13.7%) or none/topical/phototherapy (12.3%). The psoriasis area severity index (PASI) was regarded as the primary outcome. The Body Surface Area (BSA) and the Dermatology Life Quality Index (DLQI) were additionally considered as dermatological outcomes. Probing pocket depth, recession depth, clinical attachment level, periodontal inflamed surface area, and full-mouth plaque and bleeding scores were also measured. [Correction added on July 5, 2024, after first online publication: The preceding sentence has been revised]. RESULTS: Periodontal therapy in the test group led to statistically significant lower PASI scores at 10 weeks (mean = 3.15
standard deviation [SD] = 3.78) compared to the control group (mean = 7.11
SD = 6.09) (mean difference [MD] = -4.0
95% confidence interval [CI]: -6.3, -1.6
p = .002). The test group also showed improvements in BSA (MD = -4.3) and periodontal parameters compared to the control group. DLQI only showed a non-statistically significant tendency (MD = -2.0). CONCLUSION: Steps 1-2 of periodontal therapy showed an additional effect over conventional dermatological treatment in reducing the severity and extent of psoriasis (Clinicaltrials.gov: NCT05311501).