Observational prospective study to determine the association and diagnostic utility of salivary nitrites levels in periodontitis

Aim: There has been found that patients with chronic periodontitis showed higher salivary concentrations of reactive nitrogen species (RNS) than healthy subjects. However, only a study from elderly Koreans has reported that high salivary RNS concentrations are associated independently with periodontitis. Thus, the objective of this study was to determine whether salivary nitrites concentrations are associated with periodontitis controlling risk factors in other populations (such as European population).

Methods: This was a prospective and observational study carried out in a Dental Clinic including European subjects without periodontitis (including subjects with periodontal health or with localized gingivitis in <30% sites) or with periodontitis (thus, with loss of periodontal tissue). The levels of nitrite in saliva were assessed using the Griess method. A multivariate regression analysis was performed to determine that variables were associated independently with periodontitis. To determine the association between salivary malondialdehyde levels and severity of periodontitis was used Spearman's rho correlation coefficient. A receiver operating characteristic analysis with salivary nitrites levels and periodontitis diagnostic was performed.

Results: Subjects with periodontitis (n=54) in comparison to subjects without periodontitis (n=30) had higher salivary nitrites levels (p=0.003), higher rate of arterial hypertension history (p=0.02) and were older age (p<0.001). Nevertheless, differences between subject with and without periodontitis in other variables were not found. A positive correlation was found between salivary nitrites levels and periodontitis severity (rho=0.23; p=0.04). Multiple logistic regression analysis showed that elevated salivary nitrites levels > 209 nmol/mL were associated with periodontitis controlling for arterial hypertension history and age (OR=10.212; 95% CI=2.665-39.128; p=0.001) and controlling for diabetes mellitus and smoker (OR=8.793; 95% CI=3.038-24.450; p<0.001). The area under the curve for periodontitis diagnostic by salivary nitrites levels was of 69% (95% CI=58%-79%; p<0.001). The selected point of salivary nitrites levels > 209 nmol/mL for periodontitis diagnostic had 72% of sensitivity (58%-84%), 77% of specificity (58%-90%), 3.1 of p ositive likelihood ratio (1.6-6.1), 0.4 of negative likelihood ratio (0.2-0.6), 85% of positive predictive value (74%-92%) and 61% of negative predictive value (49%-71%).

Conclusions: Salivary nitrites concentrations could be associated independently with periodontitis, could be associated with periodontitis severity and could help in periodontitis diagnosis in a European population according to the results of this preliminary study.