Saliva: Diagnostic Tool in Oral and Systemic Disease

Saliva testing has been extensively studied as a non-invasive diagnostic tool.  The abundance of salivary biomarkers (DNA, RNA, hormones, antibodies, growth factors, enzymes, microbes and proteins) offers the opportunity to diagnose autoimmune disorders, cardiovascular disease, diabetes, HIV, oral cancer, dental caries and periodontal disease.

Pathology Identified with Salivary Biomarkers and Currently Available Saliva Test Kits

  • Autoimmune Disorders
    • Sjogren’s syndrome (SS): Salivary secretions exhibit elevated levels of antibodies and cytokines (IgA, IgG, PG-E2, IL-6). Salivary analysis identifies 28 proteins which are significantly modified by SS as well as pSS biomarker which is diagnostic for SS.
    • Cystic Fibrosis (CF): Mutations in the CF transmembrane conductance regulator protein lead to the chronic inflammation process which occurs in CF. CF patients also exhibit high salivary levels of chloride, potassium and sodium ions as well as lower salivary pH.  These salivary changes are related to the chronic oxidative and inflammatory process activity and are biomarkers which identify and assist in the monitoring of CF.
  • Cardiovascular Disease
    • Increased levels of C-reactive protein (CRP) can contribute to arterial plaques and cardiovascular complications, including heart attack. It is also possible to detect the biomarker cardiac troponin (cTn) in the saliva of individuals suffering from heart attack.  The salivary CRP and cTn levels have been found to correlate with plasma levels and are an effective way to diagnose and monitor heart attack.
  • Diabetes
    • 52 proteins are differently expressed as diabetes-related inflammatory salivary biomarkers. Salivary testing will likely be a future alternative to the more invasive pinprick test.
  • HIV:
    • OraSure Technologies provides an over-the-counter OraQuick In-Home HIV Test and OraQuick HIV Self-Test to detect both HIV-1 and HIV-2 viruses with an oral swab. The reported specificity and sensitivity of this test is 99.98% compared with laboratory analysis utilizing blood samples.
  • Oral Squamous Cell Carcinoma (OSCC)
    • There are many oral cancer salivary biomarkers. A significant salivary biomarker for OSCC is the presence of human papillomavirus (HPV) with 60% of OSCC tumors being associated with HPV-16. The OraRisk HPV test from OralDNA Labs is commercially available to help identify individuals who are at risk.
  • Dental Caries
    • The presence and progression of dental caries is dependent upon multiple factors and at this time there is no one test that has shown consistent accuracy in detecting caries. The CRT Bacteria Salivary Test from Ivoclar-Vivadent can detect high levels of salivary S. mutans and Lactobacilli which helps in identifying individuals (especially children) who may be at a higher risk for dental caries.  If high salivary bacterial load is detected, education on reducing additional risks factors and encouraging impeccable oral hygiene and nutrition could be beneficial.
  • Periodontal Disease
    • Research has shown that variations in more than 70 genes can be responsible for periodontal disease. MyPerioID from OralDNA Labs can detect genotypic status of IL-6 in the saliva which is a significant risk factor for chronic periodontitis.  In addition, MyPerioPath from OralDNA can detect the presence of matrix metalloproteinase-8 (MMP-8) as well as the bacterial presence of Prophyromonas gingivalis, Tannerella forsythia and Prevotella intermedia in the gingival crevicular fluid which indicates the progression of periodontitis.

Many diseases are undetected until a late phase where morbid symptoms become apparent.  The utilization of saliva testing can show the current physiological state of an individual and assist in early diagnosis and prevention of disease.  Salivary-based diagnostic techniques can potentially allow screening for specific diseases in a non-invasive, cost-effective way.  More research needs to be done to standardize and validate the salivary collection methods and biomarkers.  It is hopeful, however, that salivary tests will pave the way for chair-side diagnosis of multiple oral and systemic diseases in dental offices.

Reference:

Javaid, M.A, Ahmed, H.S, Durand, R, Tran, S.D. Saliva as a diagnostic tool for oral and systemic diseases. J Oral boil Craniofac Res 2016 Jan-Apr; 6(1): 66-75