Association of Salivary Asprosin and RBP4 Levels in Periodontitis Patients with Varying Waist-to-Height Ratios: A Case–Control Study

An observational case–control study aimed to assess the salivary concentrations of asprosin and retinol-binding protein 4 (RBP4), and their correlation in periodontitis patients with varying waist-to-height ratios (WHtR) compared with periodontally healthy controls. This study involved 120 systemically healthy participants: 30 periodontally healthy with low obesity risk (HLR, WHtR < 0.5), 30 periodontally healthy with high obesity risk (HHR, WHtR ≥ 0.5), 30 periodontitis patients with low obesity risk (PLR, WHtR < 0.5), and 30 periodontitis patients with high obesity risk (PHR, WHtR ≥ 0.5). Unstimulated saliva samples were obtained, clinical measures recorded, and salivary concentrations assessed using enzyme-linked immunosorbent assay. The Shapiro–Wilk test was employed to assess data normality. One-way analysis of variance, Bonferroni post hoc analysis, independent t-test, and chi-square test were employed for group comparisons with a p-value of < 0.05. Pearson's correlation was utilized to investigate the relationships between salivary biomarkers and periodontal measures. Multiple regression analysis was employed to evaluate various determinants of biomarker levels. Receiver operating characteristic (ROC) analysis was conducted to explore discriminative performance. The salivary concentrations of asprosin and RBP4 were significantly higher in the periodontitis groups (PLR [26.12 ± 5.74 and 33.69 ± 4.01 pg/mL] and PHR [26.46 ± 9.46 and 38.01 ± 2.36 pg/mL], respectively) compared with healthy controls (HLR [6.66 ± 4.37 and 6.30 ± 6.28 pg/mL] and HHR [13.61 ± 5.61 and 12.02 ± 9.18 pg/mL], respectively) (p < 0.0001). Multiple regression analysis demonstrated that clinical attachment loss (CAL) and probing pocket depth (PPD) were significantly associated with asprosin concentrations in periodontitis patients, while WHtR, obesity status, CAL, and PPD were significantly associated with RBP4 levels (R 2 = 0.515 and 0.750, respectively). Additionally, ROC analysis suggested a promising discriminative ability of both biomarkers in distinguishing periodontitis from periodontal health, with RBP4 exhibiting higher performance than asprosin in differentiating periodontitis groups categorized by WHtR, with area under the curves 0.79 versus 0.57, respectively. Asprosin is thought to be a marker reflecting periodontal inflammation, while RBP4 appears to be associated with both periodontal inflammation and obesity and may serve as a useful biomarker for assessing the association between periodontitis and obesity status.