Development and Internal Structural Confirmation of a Composite Salivary Inflammatory Score and Its Cross-Sectional Association with Periodontal Indices in Children

Background/Objectives: Salivary inflammatory biomarkers may provide a minimally invasive summary of oral inflammatory burden, but a composite score requires biologically grounded construction and precise validation claims before clinical interpretation. We evaluated an equally weighted six-biomarker salivary inflammatory score, internally confirmed its one-factor structure, and examined cross-sectional associations with gingival, plaque and Community Periodontal Index (CPI) screening measures in children. Methods: This multicenter cross-sectional study included 1345 children aged 6–12 years from three Romanian counties. IL-6, IL-1β, TNF-α, IL-8, MRP-8/14, and CRP were measured in duplicate. The sample was split before standardization into derivation (n = 1076) and internal test (n = 269) subsets; derivation-set parameters were applied unchanged to the test subset. Exploratory factor analysis was conducted in the derivation subset, and the prespecified one-factor model was assessed in the internal test subset. Adjusted GI and CPI associations used all 1345 participants; because 54 archived participant-level PI values exceeded the stated 0–3 scale and could not be adjudicated from unavailable surface-level source records, the primary PI analyses used the 1291 records within the valid 0–3 range. Results: One factor explained 89.6% of biomarker variance in the derivation subset and showed excellent fit in the internal test subset (robust χ2 = 9.422, df = 9, p = 0.399; RMSEA = 0.013; SRMR = 0.007). Each one-derivation-set-standard-deviation increase in the score was associated with higher GI (B = 0.649, 95% CI 0.626–0.673; R2 = 0.898; n = 1345) and PI (B = 0.696, 95% CI 0.672–0.719; R2 = 0.914; n = 1291). Adjusted odds ratios were 33.29 (95% CI 19.57–56.62) for CPI 1 versus CPI 0 and 442.17 (95% CI 226.14–864.58) for CPI 2 versus CPI 0. Conclusions: The study supports internal structural confirmation of a dominant one-factor biomarker construct and strong cross-sectional associations after adjustment for measured covariates. It does not establish temporal stability, between-laboratory reproducibility, diagnostic accuracy or added clinical value beyond routine periodontal examination.