Assessment of Salivary Neutrophil Gelatinase-Associated Lipocalin (NGAL) Levels Among Subjects With Oral Squamous Cell Carcinoma, Periodontitis, Smokeless Tobacco Users, Smokers, and Healthy Individuals: A Cross-Sectional Study

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is an inflammatory biomarker implicated in periodontal tissue destruction and tumor progression. Tobacco use, both smoked and smokeless, is a key risk factor for periodontitis and oral squamous cell carcinoma (OSCC) and may influence NGAL expression. However, comparative evaluation of salivary NGAL levels across periodontal disease, tobacco users, and OSCC remains limited. Aim: To compare salivary NGAL levels among patients with OSCC, periodontitis, smoked tobacco users, smokeless tobacco (SLT) users, and healthy controls, and to assess the correlation of NGAL levels with periodontal clinical parameters. Materials and methods: This cross-sectional study included 125 participants divided into five groups (n = 25 each): OSCC, periodontitis, smokers, SLT users, and healthy controls. Periodontal parameters such as Oral Hygiene Index (OHI), Russell’s Periodontal Index, probing pocket depth (PPD), and clinical attachment level (CAL) were recorded. Unstimulated whole saliva samples were collected and analyzed for NGAL levels using enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using analysis of variance (ANOVA) with Tukey’s post-hoc test and Pearson’s correlation analysis (p < 0.05). Results: Salivary NGAL levels showed a statistically significant difference among all groups (p < 0.001), with the highest levels observed in SLT users, followed by patients with OSCC, patients with periodontitis, smoked tobacco users, and healthy controls. Periodontal parameters were significantly worse in patients with periodontitis and SLT users, with no significant difference between these two groups. Salivary NGAL exhibited strong positive correlations with OHI, Russell’s Index, PPD, and CAL (p < 0.001). Conclusion: Elevated salivary NGAL levels are significantly associated with periodontal disease severity, both smoked and SLT use, and OSCC. NGAL shows promise as a potential non-invasive biomarker for assessing inflammatory burden and disease risk in periodontal and tobacco-related oral conditions.