Diagnostic ability of salivary IL-6 and MMP-9 biomarkers in different stages of periodontitis (case-control study)

Background: Recently, the importance of salivary proteins as periodontal disease biomarkers creates “high-impact diagnostics” that significantly influence clinical judgment, patient outcomes, and healthcare costs. The study aimed to evaluate the diagnostic accuracy of salivary biomarkers Matrix metalloproteinase-9 (MMP-9) as well as interleukin-6 (IL-6) in distinguishing between various stages of periodontitis and healthy individuals. Materials and Methods: A case-control study of 120 volunteers was classified into four groups based on periodontal health: healthy controls, stage I, II, and III periodontitis. Salivary samples were collected, and an enzyme-linked immune sorbent assay was employed to measure IL-6 and MMP-9 levels. The diagnostic precision of both biomarkers was evaluated using the area under curve (AUC) and receiver operating characteristic (ROC). Results: IL-6 demonstrated strong diagnostic ability; its AUC values ranged from 0.888 to 1 across comparisons. Precisely, in differentiating control from stage III periodontitis, IL-6 showed a perfect diagnostic efficacy at a cut-off of 5.75. Conversely, MMP-9 exhibited diverse AUC values according to the stage of disease with a cut-off of 1.715, when comparing the control to stage III. Conclusion: Salivary IL-6 consistently demonstrates robust diagnostic accuracy in distinguishing periodontitis stages, suggesting its potential as a valuable tool for non-invasive periodontal assessments. MMP-9 also presents diagnostic promise, and its application is more stage-specific.