Oral Hygiene and Systemic Biomarkers in Polycystic Ovary Syndrome: Exploratory Phenotype-Specific Associations with Salivary Zonulin

Background/Objectives: Polycystic ovary syndrome (PCOS) is heterogeneous, and oral hygiene indices may not capture the microbial and inflammatory features relevant to different phenotypes. We evaluated oral hygiene, salivary microbiota, salivary zonulin, and systemic biomarkers in classical PCOS and non-classical PCOS (Rotterdam phenotypes C and D). Methods: This cross-sectional analysis used 110 complete records from the master dataset: 42 women with classical PCOS, 45 with non-classical PCOS, and 23 controls. Oral hygiene was assessed using the Oral Hygiene Index-Simplified (OHI-S). Serum interleukin-1 beta (IL-1β), anti-Müllerian hormone (AMH), fasting glucose, and insulin were assessed, salivary zonulin was measured by ELISA, and salivary Lactobacillus, Prevotella, and Bifidobacterium profiles were evaluated by qPCR. Spearman correlations were tested as an exploratory family of 24 phenotype-specific comparisons using the Benjamini–Hochberg false discovery rate (FDR); a BMI-adjusted sensitivity analysis was also performed for the debris–zonulin association. Results: OHI-S indices and HOMA-IR did not differ among groups. Raw between-group differences for IL-1β and AMH did not remain significant after FDR correction. Prevotella and Bifidobacterium qPCR-derived abundance differed among groups, whereas Lactobacillus did not. In non-classical PCOS, the Debris Index correlated positively with salivary zonulin (ρ = 0.46, raw p = 0.002, FDR q = 0.036; bootstrap 95% CI 0.14–0.73); the BMI-adjusted partial Spearman correlation was similar (ρ = 0.47, p = 0.001). The inverse calculus–zonulin association in classical PCOS and the total OHI-S–zonulin association in non-classical PCOS did not remain significant after FDR correction. Conclusions: OHI-S was not a discriminatory marker of PCOS status in this cohort. One phenotype-specific debris–zonulin association remained after correction, but the cross-sectional design, restricted OHI-S range, and small control group require cautious interpretation. These findings support further hypothesis-driven studies rather than a clinical claim for an established oral–gut axis in PCOS.