Salivary Diagnostics

Key Points 

  • Saliva and other oral fluids (e.g., gingival crevicular fluid, combined secretions of minor salivary glands) support the health of soft and hard tissues in the oral cavity.
  • Biocomponents found in oral fluid include proteins and related molecules, nucleic acid components (e.g., human and microbial DNA, mRNA and microRNA), and endogenous and exogenous metabolites.
  • Oral fluid testing by clinical laboratories for the detection of viral infection (e.g., SARS CoV-2, HIV, HPV, HSV) or other infectious agents (e.g., Candida albicans), drug metabolizer status, and detection of illicit drugs is generally regulated through the Clinical Laboratory Improvement Amendments of 1988 (CLIA).
  • Challenges to the use of oral fluids for diagnostic purposes include identification of disease-specific markers, sensitivity and specificity of tests, and standardization of collection/storage of salivary samples.
  • Several diagnostic tests that use saliva or oral fluid samples for detection of SARS CoV-2 have received emergency use authorization from the U.S. Food and Drug Administration (FDA).
  • As of June 2021, there are no FDA-approved salivary diagnostic tests for evaluating risk of periodontal disease or dental caries, or head and neck cancer. 
Introduction

Saliva and other oral fluids (e.g., gingival crevicular fluid, combined secretions of minor salivary glands) support the health of soft and hard tissues in the oral cavity.1-7 The protective functions of saliva include maintaining a neutral oral pH, cleaning and remineralizing teeth, facilitating swallowing and digestion, and protecting oral tissue against desiccation and invasion by microorganisms.2, 7 Adequate saliva is essential for maintaining oral health, and reduced salivary secretion (i.e., hyposalivation) or xerostomia (i.e., dry mouth) can contribute to oral problems such as dental caries, mucositis, fungal infections, and periodontal diseases.8-11

Potential advantages of using saliva for disease diagnostics include ease of access, noninvasive sample collection, increased acceptance by patients, and reduced risks of infectious disease transmission.12-14 Readily accessible fluids include whole saliva, secretions from specific glands, mucosal transudate or gingival crevicular fluid.13 However, the various techniques and durations of collecting saliva and other oral fluids (e.g., spitting, drooling, dribbling, and collection with or without coughing) can affect the precision and determination of biomarkers of interest. 

Saliva is a heterogeneous biofluid that can also include epithelial cells and leukocytes.15 Composition of saliva is variable as specimens will be affected by the time of day they are collected, the location where oral fluid is collected, and the sample storage conditions, including the time to analysis.16-19 To date, there are no established uniform criteria for the collection of human saliva.2 

There continues to be interest in oral fluid as a non-invasive diagnostic medium for rapid, point-of-care testing.12-14 Interest in saliva tests expanded significantly with emergence of the coronavirus disease 2019 (COVID-19) pandemic, which fueled development of rapid diagnostic tests using alternative sample specimens, such as saliva, for improved detection of individuals with SARS CoV-2 infection.20 During early stages of the pandemic, initial studies showed detectable viral loads of SARS CoV-2 in saliva21-24 and in individuals showing no symptoms of COVID-19 (asymptomatic).25 Subsequently, studies that evaluated saliva specimens using polymerase chain reaction (PCR) testing for COVID-19 showed that such tests performed relatively well.26-30 One meta-analysis31 reported 91% sensitivity for saliva tests of previously confirmed COVID-19 patients compared with 98% sensitivity for nasopharyngeal swabs (a commonly used specimen type for COVID-19 diagnosis). 

Sampling oral fluids, instead of blood, provides an accessible medium for detecting a range of candidate biomarkers, such as proteins, electrolytes, hormones, antibodies and DNA/RNA, as well as other substances such as therapeutic or recreational drugs.1 While oral fluid assessment has been suggested to be useful in screening for or diagnosing oral or systemic diseases, monitoring viral or fungal infections, detecting drug exposure, and evaluating endocrine disorders and cancer risk, evidence of utility for most of these purposes is limited, and further clinical validation research is required. 

Currently, oral fluid testing by clinical laboratories is regulated under the Clinical Laboratory Improvement Amendments of 1988 (CLIA). The federal CLIA regulatory standards apply to clinical laboratories and any facility examining human specimens for diagnosis, prevention, treatment of a disease or for assessment of health. CLIA regulations are designed to help ensure test results are accurate and reliable.32 However, the CLIA program does not address the clinical validity of any test—that is, the accuracy with which the test identifies, measures, or predicts the presence or absence of a clinical condition or predisposition in a patient.32 

To make a claim of clinical validity, a test must be submitted to the U.S. Food and Drug Administration (FDA), which regulates tests under the Federal Food Drug, and Cosmetic Act. The clinical validity of a test is evaluated by FDA in its premarket clearance and approval processes.32 

As of mid-2021, several tests have received FDA emergency use authorization for detection of SARS CoV-2 infection using saliva collected from individuals with COVID-19 symptoms. Some of the tests allow saliva specimens to be self-collected at home (and/or in special collection devices), or to be collected in a health care setting (when determined to be appropriate by a health care provider).33 In June 2021, the FDA granted emergency use authorization to the first point-of-care antibody assay that uses oral fluid samples (i.e., gingival crevicular fluid) for qualitative detection of total antibodies (e.g., IgG, IgA, IgM) to SARS CoV-2 (the antibody test is intended for use in diagnosing recent or prior infection with SARS CoV-2).34

In addition, there are two direct-to-consumer (DTC), oral fluid tests that have received marketing authorization from FDA, which test for gene alleles associated with increased cancer risk. The FDA includes more information on DTC genomic tests at the following website: https://www.fda.gov/medical-devices/in-vitro-diagnostics/direct-consumer-tests.

Oral Fluid Biocomponents

Although a variety of biocomponents (Table 1) are found in oral fluid including proteins and related molecules, nucleic acid components (e.g., human and microbial DNA, messenger RNA [mRNA] and microRNA), and endogenous and exogenous metabolites,12, 13 a number of factors, including collection methods used to obtain the sample (e.g., stimulated or unstimulated), affect their concentration.35

Factors affecting the ability to accurately assess biomarkers in samples obtained from the oral cavity depend not only on marker biochemistry, the source and type of the sample, and the mechanism by which the marker enters the oral cavity,13 but marker stability.36, 37 Proteomic technologies significantly improved the ability to identify candidate biomarkers at the molecular level. These technologies have advanced cataloging the human salivary biocomponents and evaluating their diagnostic value.19, 38

Table 1. Examples of Biocomponents Detectable in Oral Fluid2, 6, 12-14, 39-49

 Biocomponent Class  Examples
 Hormones Cortisol, androgens, estriol, estrogen, progesterone, aldosterone, melatonin, insulin
 Cytokines Interleukins (IL-1beta, IL-6, IL-8), tumor necrosis factor, troponin
 Antibodies  IgG, IgA
 Proteins/Enzymes Amylase, pepsin, matrix metalloproteinases, C-reactive protein (CRP), mucins,
lactoferrin, antimicrobial peptides (cystatin, hystatin, statherin, calprotectin)
 Growth Factors  Epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) insulin-like growth factor
 Nucleic Acids Human and microbial DNA, mRNA, microRNA, tRNA-derived small RNA (sRNA)
 Viruses HIV, HSV-1, HSV-2, EBV, HPV, CMV, VZV, HCV, Anelloviridae
 Bacteria  P. gingivalis, S. mutans, Lactobacillus spp, T. forsythia, E. coli, H. pylori, M. tuberculosis
 Fungi  Candida, Aspergillus
 Drugs Anticonvulsants, chemotherapeutic agents
(including antibiotics and antineoplastic agents), analgesics, drugs of abuse, ethanol
 Metabolites/Electrolytes Phosphate, calcium, sodium, potassium, glucose, chloride, nitrate, uric acid,
amino acids, lipids, carbohydrates
 Tumor Markers CA 15-3, HER2/neu, CA 19-9, p53, leptin, CA 125, alpha fetoprotein, CEA, somatic
mutations in tumor suppressor genes, loss of heterozygosity, promoter
hypermethylation of genes, microsatellite DNA alterations

The salivary genome consists of both human and microbial DNA.13 Nearly 70% of the salivary genome is of human origin, whereas the remaining 30% is from the oral microbiota.1

Testing for Salivary Biomarkers of Oral or Systemic Diseases

The ability to determine the presence or absence or even to quantify the amount of a biomarker in oral fluids is not synonymous with its being of clinical significance. As of mid-2021, there are no FDA-approved salivary diagnostic tests for evaluating risk of periodontal disease, dental caries, or head and neck cancer.

Oral fluid contains secretions from the major and minor salivary glands, oro-nasopharyngeal secretions, gingival crevicular fluid, and cellular debris. The mixture of fluids obtained varies depending on the collection method used (e.g., spitting, suctioning, drooling, draining, or collection on some type of absorbent material).2 In addition, drug concentrations can be affected by the collection method, as well as by whether saliva stimulation methods were used. Several collection devices are commercially available in the United States and they generally involve collection on absorbent material (e.g., foam pad). Drug concentrations may also vary depending on how the oral fluid is recovered from the collection device (e.g., by centrifugation or by applying pressure). Another issue is that drug concentrations may not reflect blood levels because of residual amounts of drug (specifically those ingested or smoked) remaining in the oral cavity after recent use.

Currently available oral fluid tests have been developed for the detection of specific infectious agents (such as SARS CoV-2, HIV, HPV, HSV, Candida albicans, etc.),50, 51 drug metabolizer status,50 and detection of illicit drugs52-55. Oral fluid tests are capable of screening over 20 drugs of abuse (e.g., cocaine, amphetamines, ethanol).53-55 However, the clinical insight gained from an oral fluid test that measures presence or absence of oral HPV may be of limited value for predicting oropharyngeal squamous cell carcinoma risk56 or post-treatment prognosis57 because the test does not account for virus clearance.

Early Evidence from Systematic Reviews on Efficacy of Salivary Diagnostics for Oral Diseases 

A search of MEDLINE via PubMed Clinical Queries for systematic reviews was conducted in 2018 (plus a supplemental search in mid-2021) for pertinent systematic reviews published within the last 8 years using the following search string: systematic[sb] AND ((saliva* OR oral fluid*) AND (diagnosis OR diagnostic* OR biomarker*)). The following section summarizes the results of the identified systematic reviews with respect to saliva/oral fluid testing and oral disease(s) affecting the oral cavity.

Cancer (including Oral and Oropharyngeal Cancer)

A 2017 guideline and systematic review58, 59 from the ADA Center for Evidence-Based Dentistry on the use of adjuncts in the evaluation of potentially malignant disorders in the oral cavity made a conditional statement based on low quality evidence recommending against the use of commercially available salivary adjuncts for the evaluation of potentially malignant disorders among adult patients with or without clinically evident, seemingly innocuous, or suspicious oral lesions, and that "their use should be considered only in the context of research."

Recent reviews that have examined the potential of human salivary microRNAs, cell-free nucleic acids, mRNA, cytokines and peptide markers find the data on their utility for cancer diagnosis, progression prediction, or determining susceptibility for development of mucositis following radiotherapy to be preliminary and to require further clinical validation.60-67

Periodontal Disease 

Recent studies and systematic reviews demonstrate the continued research interest in investigating panels of oral biomarkers in saliva and gingival crevicular fluid to assist in screening and diagnosis of periodontal disease.68-78 Using the revised classification system for periodontal diseases (proposed by the 2017 World Workshop on Periodontal and Peri-implant Diseases and Conditions),79 researchers have continued to evaluate potential candidate biomarkers, expression patterns of microRNAs, point-of-care tests and diagnostic models for predicting and identifying periodontal disease.80-83

Research on diagnostic models and the predictive accuracy of salivary biomarker panels for diagnosing periodontal disease has steadily advanced but requires further clinical validation in larger cohorts.71, 73 Such research will entail highly accurate measurement studies and statistical analyses, which are further complicated because analytes are only present in trace amounts in saliva, and saliva contains bacterial proteases that can degrade protein biomarkers.71, 73, 76, 84
 
A 2017 literature review85 attempted to determine whether measurement of the inflammatory cytokines IL-1beta or TNF-alpha in saliva could be used as markers associated with clinical evidence of periodontal disease. Fifteen papers meeting selection criteria were included in the qualitative review; the authors determined that meta-analysis could not be performed because of between-study heterogeneity. The review concluded that although salivary IL-1beta and TNF-alpha are associated with early periodontal disease and increase with disease progression, they were characterized as “promising tools” in the early diagnosis of periodontal diseases. The results of this review are hypothesis generating about the potential clinical utility of these salivary markers.

The association between chronic periodontal disease and IL-8 levels in oral fluids (gingival crevicular fluid [17 studies] and saliva [4 studies]), as well as gingival tissue biopsies (10 studies), was explored in a 2017 systematic review and meta-analysis.86 The systematic review showed conflicting associations for both saliva and gingival crevicular fluid IL-8 concentrations with chronic periodontitis, while higher IL-8 concentrations in gingival tissue were found to be more consistently associated with chronic periodontitis. Separate meta-analyses were performed for the associations with salivary IL-8 (2 studies) and gingival crevicular fluid IL-8 (7 studies), finding mixed results for salivary IL-8 and lower concentrations of IL-8 in gingival crevicular fluid of patients with chronic periodontitis. 

A systematic review75 of measurement of matrix metalloproteinase-8 (MMP-8) in gingival crevicular fluid and saliva as a potential marker of periodontal disease included six studies meeting selection criteria. Although the studies found significantly higher levels of MMP-8 in the oral fluid of patients with periodontal disease compared with healthy controls as well as increased levels in patients presenting with more advanced periodontal disease, the authors found that the findings only “imply the potential adjunctive use of MMP-8 in the diagnosis of periodontal disease.” Another systematic review on MMP-8 levels found significantly higher levels of salivary MMP-8 in patients with periodontal disease, but concluded that “further high-quality studies are still needed to verify [this] conclusion.”87

Other Conditions 

Oral Lichen Planus
Two systematic reviews evaluated the evidence for the relationship between salivary and serum levels of IL-6 or TNFalpha and oral lichen planus.88-89 The meta-analyses by Liu et al.88 (salivary and serum IL-6 analyzed separately; 5 studies each) found significant differences in serum and salivary IL-6 levels between patients with disease and healthy controls, but called for additional research to confirm their meta-analytic findings. The meta-analyses by Mozaffari et al.89 (salivary and serum TNFalpha analyzed separately; 7 studies each) found higher levels of TNFalpha in saliva compared with serum in patients with oral lichen planus, suggesting that the salivary marker may be more useful than serum measurement for diagnosis and monitoring treatment; however, the authors cautioned that confounding factors such as age, stress, smoking and genetics should be taken into consideration when interpreting results.

A 2019 systematic review reported elevated serum and salivary IL-4 levels in patients with oral lichen planus, but noted that secondary infections could influence its concentration.90 Two other systematic reviews indicated that salivary cytokine and nitric oxide measurements and elevated levels of salivary IL-8 may have potential applications in monitoring disease activity in patients with oral lichen planus.91, 92

Laryngopharyngeal Reflux
Two systematic reviews93, 94 evaluated the utility of salivary pepsin assessment as a diagnostic biomarker of laryngopharyngeal reflux, a condition in which stomach acid and/or gastric content flow back up the esophagus and into the larynx or throat. The review by Calvo-Henriquez et al.93 included 12 studies meeting study selection criteria; eight of these evaluated salivary pepsin as a biomarker for laryngopharyngeal reflux. The review concluded that although pepsin might be a reliable marker of disease, “questions remain about optimal timing, location, nature, and threshold values for pepsin testing,” and that future research is required. The review and meta-analysis by Wang et al.94 was limited to salivary pepsin measurement; 11 studies met study selection criteria. This review concluded that although pepsin in saliva has moderate value in the diagnosis of laryngopharyngeal reflux, because the cutoff value used could affect its diagnostic value, further research is required “to find the optimal method to detect salivary pepsin.” 

General

Studies of the saliva metabolome have identified 853 metabolites and metabolic species in human saliva.95 A saliva ontology-based database and a Human Salivary Proteome Wiki have also been established to support data accessibility for expanded transcriptomic and proteomic research.96. 97 The field of salivary diagnostics drew extensive research interest and public support during the COVID-19 pandemic, in the U.S. and internationally, as communities searched for simple, non-invasive and accurate testing options for improved public health surveillance and protective measures. 

The use of saliva for disease diagnostics and surveillance has considerable potential for future diagnostic tests for oral and systemic diseases, including biosensors that could potentially provide continuous monitoring of salivary analytes associated with oral or systemic health.98 Extensive research, however, is still required to identify and assess oral fluid biomarkers and to validate saliva-based testing modalities for future clinical application.98, 99 Similar recommendations are presented in a 2014 “critical review”100 of the literature for salivary and biofilm diagnostics found that the majority of studies published at that time were primarily concerned with validating metrics and identifying biomarkers with diagnostic potential. A 2015 review101 similarly concluded that “[m]ost reports on discovered candidate [salivary] biomarkers have been only preliminary and require extensive validation in large patient or subject cohorts before they can be translated into real world diagnostic and screening applications.” 

Summary

Large-scale, multicenter clinical trials and independent validation studies are required to establish evidence of clinical utility of salivary and oral fluid diagnostics in the early diagnosis and/or monitoring of oral cancer and other diseases or conditions. Current challenges include identification of disease-specific markers, establishing sensitivity and specificity of home-use and point-of-care tests using saliva specimens, and standardization of collection/storage of salivary samples.43 Refinement of oral fluid screening and diagnostic tests may further elucidate our understanding of the relationship between oral health and overall health. Lastly, as of mid-2021, there are oral fluid-based diagnostic tests available for the detection of HIV infection, drugs of abuse and SARS CoV-2 (under the FDA’s Emergency Use Authorization authority). However, no FDA-approved salivary diagnostic tests for evaluating risk of periodontal disease, dental caries, or head and neck cancer.

References
  1. Zhang CZ, Cheng XQ, Li JY, et al. Saliva in the diagnosis of diseases. Int J Oral Sci 2016;8(3):133-7.
  2. Chojnowska S, Baran T, Wilinska I, et al. Human saliva as a diagnostic material. Adv Med Sci 2017;63(1):185-91.
  3. Lynge Pedersen AM, Belstrøm D. The role of natural salivary defences in maintaining a healthy oral microbiota. Journal of Dentistry 2019;80:S3-S12.
  4. Fábián TK, Hermann P, Beck A, Fejérdy P, Fábián G. Salivary defense proteins: their network and role in innate and acquired oral immunity. Int J Mol Sci 2012;13(4):4295-320.
  5. Uriarte SM, Edmisson JS, Jimenez-Flores E. Human neutrophils and oral microbiota: a constant tug-of-war between a harmonious and a discordant coexistence. Immunological reviews 2016;273(1):282-98.
  6. Saitou M, Gaylord EA, Xu E, et al. Functional Specialization of Human Salivary Glands and Origins of Proteins Intrinsic to Human Saliva. Cell Rep 2020;33(7):108402.
  7. Dawes C, Pedersen AM, Villa A, et al. The functions of human saliva: A review sponsored by the World Workshop on Oral Medicine VI. Arch Oral Biol 2015;60(6):863-74.
  8. Atkinson JC, Grisius M, Massey W. Salivary hypofunction and xerostomia: diagnosis and treatment. Dent Clin North Am 2005;49(2):309-26.
  9. Diaz-Arnold AM, Marek CA. The impact of saliva on patient care: A literature review. J Prosthet Dent 2002;88(3):337-43.
  10. Featherstone JD. The continuum of dental caries--evidence for a dynamic disease process. J Dent Res 2004;83 Spec No C:C39-42.
  11. Papas AS, Joshi A, MacDonald SL, et al. Caries prevalence in xerostomic individuals. J Can Dent Assoc 1993;59(2):171-4, 77-9.
  12. Genco RJ. Salivary diagnostic tests. J Am Dent Assoc 2012;143(10 Suppl):3s-5s.
  13. Malamud D. Saliva as a diagnostic fluid. Dent Clin North Am 2011;55(1):159-78.
  14. Wong DT. Salivary diagnostics. Oper Dent 2012;37(6):562-70.
  15. Theda C, Hwang SH, Czajko A, et al. Quantitation of the cellular content of saliva and buccal swab samples. Scientific Reports 2018;8(1):6944.
  16. Dawes C. Circadian rhythms in human salivary flow rate and composition. J Physiol 1972;220(3):529-45.
  17. Yano Y, Hua X, Wan Y, et al. Comparison of oral microbiota collected using multiple methods and recommendations for new epidemiologic studies. mSystems 2020;5(4).
  18. Lee RA, Herigon JC, Benedetti A, Pollock NR, Denkinger CM. Performance of saliva, oropharyngeal swabs, and nasal swabs for SARS-CoV-2 molecular detection: a systematic review and meta-analysis. J Clin Microbiol 2021;59(5).
  19. Proctor GB, Shaalan AM. Disease-Induced Changes in Salivary Gland Function and the Composition of Saliva. J Dent Res 2021:220345211004842.
  20. Cañete MG, Valenzuela IM, Garcés PC, et al. Saliva sample for the massive screening of SARS-CoV-2 infection: a systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol 2021;131(5):540-48.
  21. Byrne R, Kay G, Kontogianni K, et al. Saliva alternative to upper respiratory swabs for SARS-CoV-2 diagnosis. Emerging Infectious Disease journal 2020;26(11):2769.
  22. To KK, Tsang OT, Yip CC, et al. Consistent Detection of 2019 Novel Coronavirus in Saliva. Clin Infect Dis 2020;71(15):841-43.
  23. Huang N, Pérez P, Kato T, et al. SARS-CoV-2 infection of the oral cavity and saliva. Nature Medicine 2021;27(5):892-903.
  24. Shirazi S, Stanford CM, Cooper LF. Characteristics and Detection Rate of SARS-CoV-2 in Alternative Sites and Specimens Pertaining to Dental Practice: An Evidence Summary. J Clin Med 2021;10(6).
  25. Herrera LA, Hidalgo-Miranda A, Reynoso-Noverón N, et al. Saliva is a reliable and accessible source for the detection of SARS-CoV-2. Int J Infect Dis 2021;105:83-90.
  26. Fernandes LL, Pacheco VB, Borges L, et al. Saliva in the Diagnosis of COVID-19: A Review and New Research Directions. J Dent Res 2020;99(13):1435-43.
  27. Kojima N, Turner F, Slepnev V, et al. Self-collected oral fluid and nasal swab specimens demonstrate comparable sensitivity to clinician-collected nasopharyngeal swab specimens for the detection of SARS-CoV-2. Clin Infect Dis 2020.
  28. Azzi L, Maurino V, Baj A, et al. Diagnostic salivary tests for SARS-CoV-2. J Dent Res 2021;100(2):115-23.
  29. Wyllie AL, Fournier J, Casanovas-Massana A, et al. Saliva or Nasopharyngeal Swab Specimens for Detection of SARS-CoV-2. The New England journal of medicine 2020;383(13):1283-86.
  30. Butler-Laporte G, Lawandi A, Schiller I, et al. Comparison of saliva and nasopharyngeal swab nucleic acid amplification testing for detection of SARS-CoV-2: a systematic review and meta-analysis. JAMA Internal Medicine 2021;181(3):353-60.
  31. Czumbel LM, Kiss S, Farkas N, et al. Saliva as a candidate for COVID-19 diagnostic testing: a meta-analysis. Front Med (Lausanne) 2020;7:465.
  32. Centers for Medicare and Medicaid Services. Laboratory developed tests and CLIA FAQ. 2013. https://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/Downloads/LDT-and-CLIA_FAQs.pdf. Accessed June 8, 2021.
  33. Vogels CBF, Watkins AE, Harden CA, et al. SalivaDirect: A simplified and flexible platform to enhance SARS-CoV-2 testing capacity. Med (N Y) 2021;2(3):263-80.e6.
  34. Rao PV, Nair-Shaef D, Chen S, et al. Performance and utility of an oral fluid-based rapid point-of-care test for SARS-COV-2 antibody response following COVID-19 infection or vaccination. MedRxiv [Preprint] 2021. doi: 10.1101/2021.06.28.21259657.
  35. Gardner A, Carpenter G, So P-W. Salivary metabolomics: from diagnostic biomarker discovery to investigating biological function. Metabolites 2020;10(2):47.
  36. Brogna R, Oldenhof H, Sieme H, Wolkers WF. Spectral fingerprinting to evaluate effects of storage conditions on biomolecular structure of filter-dried saliva samples and recovered DNA. Scientific reports 2020;10(1):21442-42.
  37. Dakappagari N, Zhang H, Stephen L, Amaravadi L, Khan MU. Recommendations for clinical biomarker specimen preservation and stability assessments. Bioanalysis 2017;9(8):643-53.
  38. Denny P, Hagen FK, Hardt M, et al. The proteomes of human parotid and submandibular/sublingual gland salivas collected as the ductal secretions. J Proteome Res 2008;7(5):1994-2006.
  39. Saxena S, Sankhla B, Sundaragiri KS, Bhargava A. A Review of Salivary Biomarker: A Tool for Early Oral Cancer Diagnosis. Adv Biomed Res 2017;6:90.
  40. Hemadi AS, Huang R, Zhou Y, Zou J. Salivary proteins and microbiota as biomarkers for early childhood caries risk assessment. Int J Oral Sci 2017;9(11):e1.
  41. Wong DT. Salivaomics. J Am Dent Assoc 2012;143(10 Suppl):19s-24s.
  42. Streckfus CF, Bigler LR. Saliva as a diagnostic fluid. Oral Dis 2002;8(2):69-76.
  43. Yeh CK, Christodoulides NJ, Floriano PN, et al. Current development of saliva/oral fluid-based diagnostics. Tex Dent J 2010;127(7):651-61.
  44. Malon RS, Sadir S, Balakrishnan M, Corcoles EP. Saliva-based biosensors: noninvasive monitoring tool for clinical diagnostics. Biomed Res Int 2014;2014:962903.
  45. Alkharaan H, Bayati S, Hellström C, et al. Persisting salivary IgG against SARS-CoV-2 at 9 months after mild COVID-19: a complementary approach to population surveys. J Infect Dis 2021.
  46. Hernandez MM, Banu R, Shrestha P, et al. RT-PCR/MALDI-TOF mass spectrometry-based detection of SARS-CoV-2 in saliva specimens. J Med Virol 2021.
  47. Rapson A, Collman E, Faustini S, et al. Free light chains as an emerging biomarker in saliva: Biological variability and comparisons with salivary IgA and steroid hormones. Brain Behav Immun 2020;83:78-86.
  48. Liang G, Bushman FD. The human virome: assembly, composition and host interactions. Nat Rev Microbiol 2021:1-14.
  49. Radaic A, Kapila YL. The oralome and its dysbiosis: New insights into oral microbiome-host interactions. Computational and Structural Biotechnology Journal 2021;19:1335-60.
  50. OralDNA Labs. OralDNA® Tests. https://www.oraldna.com/tests.html. Accessed May 11, 2018.
  51. JA M. COVID-19 Is a catalyst for remote sampling and telemedicine. Clinical Laboratory News.
  52. OraSure Technologies Inc. Substance Abuse Testing Products. http://www.orasure.com/products-infectious/products-infectious.asp. Accessed May 11, 2018.
  53. Valen A, Leere Øiestad Å M, Strand DH, Skari R, Berg T. Determination of 21 drugs in oral fluid using fully automated supported liquid extraction and UHPLC-MS/MS. Drug Test Anal 2017;9(5):808-23.
  54. Dawes C, Wong DTW. Role of saliva and salivary diagnostics in the advancement of oral health. J Dent Res 2019;98(2):133-41.
  55. Tang MHY, Ching CK, Poon S, et al. Evaluation of three rapid oral fluid test devices on the screening of multiple drugs of abuse including ketamine. Forensic Sci Int 2018;286:113-20.
  56. Pierce Campbell CM, Kreimer AR, Lin HY, et al. Long-term persistence of oral human papillomavirus type 16: the HPV Infection in Men (HIM) study. Cancer Prev Res (Phila) 2015;8(3):190-6.
  57. Rettig EM, Wentz A, Posner MR, et al. Prognostic Implication of Persistent Human Papillomavirus Type 16 DNA Detection in Oral Rinses for Human Papillomavirus-Related Oropharyngeal Carcinoma. JAMA Oncol 2015;1(7):907-15.
  58. Lingen MW, Abt E, Agrawal N, et al. Evidence-based clinical practice guideline for the evaluation of potentially malignant disorders in the oral cavity: A report of the American Dental Association. J Am Dent Assoc 2017;148(10):712-27.e10.
  59. Lingen MW, Tampi MP, Urquhart O, et al. Adjuncts for the evaluation of potentially malignant disorders in the oral cavity: Diagnostic test accuracy systematic review and meta-analysis-a report of the American Dental Association. J Am Dent Assoc 2017;148(11):797-813.e52.
  60. Rapado-Gonzalez O, Majem B, Muinelo-Romay L, et al. Human salivary microRNAs in Cancer. J Cancer 2018;9(4):638-49.
  61. El-Sakka H, Kujan O, Farah CS. Assessing miRNAs profile expression as a risk stratification biomarker in oral potentially malignant disorders: A systematic review. Oral Oncol 2018;77:57-82.
  62. van Ginkel JH, Slieker FJB, de Bree R, et al. Cell-free nucleic acids in body fluids as biomarkers for the prediction and early detection of recurrent head and neck cancer: A systematic review of the literature. Oral Oncol 2017;75:8-15.
  63. Gualtero DF, Suarez Castillo A. Biomarkers in saliva for the detection of oral squamous cell carcinoma and their potential use for early diagnosis: a systematic review. Acta Odontol Scand 2016;74(3):170-7.
  64. Porto-Mascarenhas EC, Assad DX, Chardin H, et al. Salivary biomarkers in the diagnosis of breast cancer: A review. Crit Rev Oncol Hematol 2017;110:62-73.
  65. Normando AGC, Rocha CL, de Toledo IP, et al. Biomarkers in the assessment of oral mucositis in head and neck cancer patients: a systematic review and meta-analysis. Support Care Cancer 2017;25(9):2969-88.
  66. Chiamulera MMA, Zancan CB, Remor AP, et al. Salivary cytokines as biomarkers of oral cancer: a systematic review and meta-analysis. BMC Cancer 2021;21(1):205.
  67. Setti G, Pezzi ME, Viani MV, et al. Salivary MicroRNA for Diagnosis of Cancer and Systemic Diseases: A Systematic Review. Int J Mol Sci 2020;21(3).
  68. Sorsa T, Alassiri S, Grigoriadis A, et al. Active MMP-8 (aMMP-8) as a Grading and Staging Biomarker in the Periodontitis Classification. Diagnostics (Basel) 2020;10(2).
  69. Al-Majid A, Alassiri S, Rathnayake N, et al. Matrix metalloproteinase-8 as an inflammatory and prevention biomarker in periodontal and peri-implant diseases. Int J Dent 2018;2018:7891323.
  70. Podzimek S, Vondrackova L, Duskova J, Janatova T, Broukal Z. Salivary Markers for Periodontal and General Diseases. Dis Markers 2016;2016:9179632.
  71. Bostanci N, Mitsakakis K, Afacan B, et al. Validation and verification of predictive salivary biomarkers for oral health. Scientific Reports 2021;11(1):6406.
  72. Wu YC, Ning L, Tu YK, et al. Salivary biomarker combination prediction model for the diagnosis of periodontitis in a Taiwanese population. J Formos Med Assoc 2018;117(9):841-48.
  73. Ghallab NA. Diagnostic potential and future directions of biomarkers in gingival crevicular fluid and saliva of periodontal diseases: Review of the current evidence. Arch Oral Biol 2018;87:115-24.
  74. Arias-Bujanda N, Regueira-Iglesias A, Balsa-Castro C, et al. Accuracy of single molecular biomarkers in saliva for the diagnosis of periodontitis: A systematic review and meta-analysis. J Clin Periodontol 2020;47(1):2-18.
  75. de Morais EF, Pinheiro JC, Leite RB, et al. Matrix metalloproteinase-8 levels in periodontal disease patients: A systematic review. J Periodontal Res 2018;53(2):156-63.
  76. Kc S, Wang XZ, Gallagher JE. Diagnostic sensitivity and specificity of host-derived salivary biomarkers in periodontal disease amongst adults: Systematic review. J Clin Periodontol 2020;47(3):289-308.
  77. Arias-Bujanda N, Regueira-Iglesias A, Balsa-Castro C, et al. Accuracy of single molecular biomarkers in gingival crevicular fluid for the diagnosis of periodontitis: A systematic review and meta-analysis. J Clin Periodontol 2019;46(12):1166-82.
  78. Baima G, Corana M, Iaderosa G, et al. Metabolomics of gingival crevicular fluid to identify biomarkers for periodontitis: A systematic review with meta-analysis. J Periodontal Res 2021.
  79. Berglundh T, Armitage G, Araujo MG, et al. Peri-implant diseases and conditions: Consensus report of workgroup 4 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. J Periodontol 2018;89 Suppl 1:S313-s18.
  80. Lee J, Lee JB, Song HY, et al. Diagnostic Models for Screening of Periodontitis with Inflammatory Mediators and Microbial Profiles in Saliva. Diagnostics (Basel) 2020;10(10).
  81. Kim HD, Lee CS, Cho HJ, et al. Diagnostic ability of salivary matrix metalloproteinase-9 lateral flow test point-of-care test for periodontitis. J Clin Periodontol 2020;47(11):1354-61.
  82. Deng K, Pelekos G, Jin L, Tonetti MS. Diagnostic accuracy of a point-of-care aMMP-8 test in the discrimination of periodontal health and disease. J Clin Periodontol 2021.
  83. Asa'ad F, Garaicoa-Pazmiño C, Dahlin C, Larsson L. Expression of MicroRNAs in Periodontal and Peri-Implant Diseases: A Systematic Review and Meta-Analysis. International journal of molecular sciences 2020;21(11):4147.
  84. Thomadaki K, Helmerhorst EJ, Tian N, et al. Whole-saliva proteolysis and its impact on salivary diagnostics. Journal of dental research 2011;90(11):1325-30.
  85. Gomes FI, Aragao MG, Barbosa FC, et al. Inflammatory cytokines interleukin-1beta and tumour necrosis factor-alpha - novel biomarkers for the detection of periodontal diseases: a literature review. J Oral Maxillofac Res 2016;7(2):e2.
  86. Finoti LS, Nepomuceno R, Pigossi SC, et al. Association between interleukin-8 levels and chronic periodontal disease: A PRISMA-compliant systematic review and meta-analysis. Medicine (Baltimore) 2017;96(22):e6932.
  87. Zhang L, Li X, Yan H, Huang L. Salivary matrix metalloproteinase (MMP)-8 as a biomarker for periodontitis: A PRISMA-compliant systematic review and meta-analysis. Medicine (Baltimore) 2018;97(3):e9642.
  88. Liu J, Shi Q, Yang S, et al. The relationship between levels of salivary and serum interleukin-6 and oral lichen planus: A systematic review and meta-analysis. J Am Dent Assoc 2017;148(10):743-49.e9.
  89. Mozaffari HR, Ramezani M, Mahmoudiahmadabadi M, Omidpanah N, Sadeghi M. Salivary and serum levels of tumor necrosis factor-alpha in oral lichen planus: a systematic review and meta-analysis study. Oral Surg Oral Med Oral Pathol Oral Radiol 2017;124(3):e183-e89.
  90. Mozaffari HR, Zavattaro E, Saeedi M, et al. Serum and salivary interleukin-4 levels in patients with oral lichen planus: A systematic review and meta-analysis. Oral Surg Oral Med Oral Pathol Oral Radiol 2019;128(2):123-31.
  91. Mozaffari HR, Sharifi R, Mirbahari S, et al. A systematic review and meta-analysis study of salivary and serum interleukin-8 levels in oral lichen planus. Postepy Dermatol Alergol 2018;35(6):599-604.
  92. Humberto JSM, Pavanin JV, Rocha M, Motta ACF. Cytokines, cortisol, and nitric oxide as salivary biomarkers in oral lichen planus: a systematic review. Braz Oral Res 2018;32:e82.
  93. Calvo-Henriquez C, Ruano-Ravina A, Vaamonde P, Martinez-Capoccioni G, Martin-Martin C. Is pepsin a reliable marker of laryngopharyngeal reflux? a systematic review. Otolaryngol Head Neck Surg 2017;157(3):385-91.
  94. Wang J, Zhao Y, Ren J, Xu Y. Pepsin in saliva as a diagnostic biomarker in laryngopharyngeal reflux: a meta-analysis. Eur Arch Otorhinolaryngol 2018;275(3):671-78.
  95. Dame ZT, Aziat F, Mandal R, et al. The human saliva metabolome. Metabolomics 2015;11(6):1864-83.
  96. Ai J, Smith B, Wong DT. Saliva Ontology: An ontology-based framework for a Salivaomics Knowledge Base. BMC Bioinformatics 2010;11(1):302.
  97. Lau WW, Hardt M, Zhang YH, Freire M, Ruhl S. The Human Salivary Proteome Wiki: A Community-Driven Research Platform. Journal of Dental Research 2021:00220345211014432.
  98. Steigmann L, Maekawa S, Sima C, et al. Biosensor and Lab-on-a-chip Biomarker-identifying Technologies for Oral and Periodontal Diseases. Front Pharmacol 2020;11:588480.
  99. Sri Santosh T, Parmar R, Anand H, Srikanth K, Saritha M. A Review of Salivary Diagnostics and Its Potential Implication in Detection of Covid-19. Cureus 2020;12(4):e7708.
  100. Novy BB. Saliva and biofilm-based diagnostics: a critical review of the literature concerning sialochemistry. J Evid Based Dent Pract 2014;14 Suppl:27-32.
  101. Nunes LA, Mussavira S, Bindhu OS. Clinical and diagnostic utility of saliva as a non-invasive diagnostic fluid: a systematic review. Biochem Med (Zagreb) 2015;25(2):177-92.

 

ADA Resources

 

Other Resources

National Institute of Dental and Craniofacial Research (NIDCR): Salivary Diagnostics

UCLA School of Dentistry

U.S. Food and Drug Administration

 

Last Updated: July 19, 2021


Prepared by:

Department of Scientific Information, Evidence Synthesis & Translation Research, ADA Science & Research Institute, LLC.


Disclaimer

Content on the Oral Health Topics section of ADA.org is for informational purposes only.  Content is neither intended to nor does it establish a standard of care or the official policy or position of the ADA; and is not a substitute for professional judgment, advice, diagnosis, or treatment.  ADA is not responsible for information on external websites linked to this website.