To evaluate the association of periodontal inflamed surface area (PISA) and maximum radiographic bone loss with rheumatoid arthritis (RA) disease activity.

In this retrospective cross-sectional study, 38 patients with RA (periodontal and rheumatologic assessments ≤10 days apart) were evaluated. Periodontal inflammatory burden (PISA), maximum radiographic bone loss, and RA activity (DAS28-ESR) were assessed. Associations were examined with Spearman correlation and multivariable linear regression adjusted for age, smoking, and diabetes.

Patients with higher PISA had greater maximum radiographic bone loss (ρ=0.441; 95% CI 0.101–0.717; p = 0.006) and higher RA disease activity (ρ=0.811; 95% CI 0.546–0.959; p < 0.001); DAS28-ESR also correlated with bone loss (ρ=0.580; 95% CI 0.306–0.777; p < 0.001). After adjustment for age, smoking, and diabetes, each 100-mm² increase in PISA was associated with a 0.740-unit higher DAS28-ESR (95% CI 0.363–1.118; p < 0.001), and each one-unit increase in DAS28-ESR was associated with 8.27 percentage points greater bone loss (95% CI 4.26–12.29; p < 0.001); age was independently associated with bone loss (0.50 points/year; 95% CI 0.18–0.83; p = 0.003). Smoking and diabetes were not significant. Effect sizes were sensitive to influential observations (PISA coefficient increased to 1.468 after exclusion), and no exploratory correlation survived Holm correction.

Periodontal inflammatory burden, radiographic bone loss, and RA disease activity were mutually associated in this single-center, seropositive cohort. These findings support evaluating periodontal inflammation and structural destruction alongside RA activity; longitudinal studies are needed to establish temporal direction.