Context:Early diagnosis of oral cancer is a priority health objective, in which oral health professionals may play a pivotal role. Detection should lead to less damage from cancer therapy and to a better prognosis.Aims:The aim was to estimate and compare the salivary lactate dehydrogenase (LDH) levels in various histological differentiation of oral squamous cell carcinoma (OSCC) patients and normal subjects.Settings and Design:Hospital-based setting, case-control study.Subjects and Methods:A case–control study was undertaken comprising 30 OSCC patients and 30 healthy controls. The OSCC patients were grouped into well-differentiated, moderately differentiated and poorly differentiated OSCC based on their histological tumor differentiation. Unstimulated whole saliva was collected, assayed for LDH levels using a standard kit and measured spectrophotometrically at 340 nm.Statistical Analysis Used:The results obtained were subjected to statistical analysis using Kruskal–Wallis and Mann–Whitney U-tests. Spearman's correlation was used to correlate the histological tumor differentiation with the salivary LDH levels.Results:The mean salivary LDH levels in the control group, well-differentiated OSCC group, moderately differentiated OSCC group, and poorly differentiated OSCC group were 117.33 ± 19.37 IU/L, 355.83 ± 16.73 IU/L, 484.18 ± 25.84 IU/L, and 620.35 ± 18.69 IU/L, respectively. The difference in the mean salivary LDH levels was statistically significant among the various groups (Kruskal–Wallis χ2 = 50.820, P < 0.001). Spearman's correlation showed significant difference between salivary LDH levels and histological differentiation of OSCC (r = −0.689, P < 0.01).Conclusions:The salivary LDH levels were higher in OSCC patients when compared to the healthy controls. The salivary LDH levels were found to be the highest among the poorly differentiated OSCC.

Saliva is one of the most ideal diagnostic tools. It is inexpensive, noninvasive, and easy to use. Other advantages like ease of collection and minimal patient discomfort make it more acceptable to the patient as well as the clinician. The most challenging aspect in salivary diagnostics is to identify the biomarker that is linked to a disease. Researches are also ongoing to develop a device that can have reliable and valid clinical applications. This chapter briefly discusses the background and current scope of salivary diagnostics, technologies for the discovery of biomarkers along with a summary of salivary sample collection, and processing methods.