Low salivary uric acid levels are independently associated with periodontitis

BACKGROUND Lower salivary uric acid concentrations, the most abundant antioxidant agent in saliva, have been observed in patients with periodontitis compared to individuals with periodontal health. However, the independent association of salivary uric acid levels with periodontitis, accounting for other risk factors, as well as its association with periodontitis severity, has not been investigated. AIM To the independent association of salivary uric acid levels with periodontitis and the association of salivary uric acid levels with the severity of periodontitis. METHODS This observational and prospective study measured salivary uric acid levels in subjects with periodontitis (characterized by periodontal loss of tissue) and in subjects without periodontitis (periodontal health or localized gingivitis in < 30% of sites). Multivariate regression analysis was performed to determine independent factors associated with periodontitis. Spearman’s rho correlation coefficient was used to assess the relationship between salivary uric acid levels and periodontitis severity. A receiver operating characteristic analysis was carried out to evaluate the diagnostic performance of salivary uric acid levels in periodontitis, reporting the area under curve (AUC) and its 95%CI. RESULTS We included 121 subjects, 61 of them with periodontitis and 60 without periodontitis (39 with periodontal health and 21 with local gingivitis). Subjects with periodontitis compared to those without periodontitis were older (P < 0.001), had higher salivary uric acid levels (P = 0.002), higher rate of arterial hypertension history (P = 0.001) and higher rate of never-smoker history (P < 0.001). The AUC for periodontitis diagnosis by salivary uric acid levels was 66% (95%CI: 57%-75%; P < 0.001) and the better cut-off point was 111 nmol/mL. Multiple logistic regression analysis showed an independent association of salivary uric acid levels < 111 nmol/mL (OR = 6.14; 95%CI: 2.015-18.721; P = 0.001) with periodontitis after controlling for age, never-smoker history and arterial hypertension. A negative correlation of salivary uric acid levels and periodontitis severity was observed (rho = -0.32; P < 0.001). CONCLUSION The two novel findings of our research were, first, that low salivary uric acid concentrations are independently associated with periodontitis, even after accounting for established risk factors. Second, salivary uric acid levels show a negative correlation with periodontitis severity.