What could saliva testing mean for dentistry?
Emerging technology may have applications in oral health care
During the COVID-19 pandemic, saliva-based tests gained attention for their ability to detect SARS-CoV-2, and this emerging technology may have applications in oral health care as well.
“As a complex biofluid containing biomarkers such as proteins, antibodies, genetic material and hormones, saliva has the potential to be used to detect other systemic and oral diseases too, but more research is needed to establish the clinical validity and reliability of these tests,” said Ashraf Fouad, D.D.S., chair of the American Dental Association’s Council on Scientific Affairs and professor at the University of Alabama at Birmingham School of Dentistry.
The ADA Forsyth Institute is among those developing saliva tests that could be used in oral health care. Its scientists are also conducting research to validate new biomarkers related to dental diseases.
“There are demands for rapid, point-of-care diagnostic tools with high sensitivity and specificity,” said Wenyuan Shi, Ph.D., CEO of ADA Forsyth. “Advanced technology today is finally getting to a stage to make this a true reality.”
Innovations on the horizon
“Saliva contains DNA from your body and also genetic information from viruses or bacteria if you're sick. That means it’s a gold mine of information — you just need the right tool to dig out what you’re looking for,” said Benjamin Wu, D.D.S., Ph.D., chief scientific officer and chief operating officer of ADA Forsyth.
For scientists at the institute, that tool is CRISPR — or clustered regularly interspaced short palindromic repeats — a technology that enables users to selectively modify the DNA of living organisms. In the case of saliva testing, the scientists can engineer CRISPR to search for specific DNA or RNA sequences in a saliva sample.
“CRISPR is like a pair of molecular scissors that scientists can program to find and cut genetic materials into visible signals,” Dr. Wu said. “It’s a tool that can look for very specific genetic instructions — like finding one sentence in a giant book.”
For example, scientists can use CRISPR to look for a virus like human papillomavirus in saliva based on its genetic code. Once CRISPR finds the target virus, it can trigger a signal that can be read by a cellphone or other device.
“AFI scientists will initially develop the tests for common oral diseases while working closely with ADA expert clinicians to identify additional targets that provide valuable insights into oral and systemic health,” Dr. Wu said.
In the lab
With some saliva tests already available and others in development, it is important for dentists to understand how these tests are regulated and what the regulations indicate about their clinical validity.
Saliva testing performed by laboratories is generally regulated by the Clinical Laboratory Improvement Amendments of 1988, according to the ADA’s Oral Health Topics webpage on salivary diagnostics.
CLIA established quality standards for laboratory testing and an accreditation program for clinical laboratories, according to the Food and Drug Administration, which administers the CLIA program with the Centers for Medicare & Medicaid Services and the Centers for Disease Control and Prevention. Through CLIA, clinical labs are certified before they can accept human samples for testing to ensure test results are accurate and reliable.
“Being a CLIA-approved lab validates that a lab is using accepted best practices and meets specific standards with respect to how they perform a test, i.e., you do the same thing every time for every specimen you receive,” said Mark Lingen, D.D.S., Ph.D., oral and maxillofacial pathologist, professor of pathology at the University of Chicago Medicine and former member of the ADA Council on Scientific Affairs. “That is a good thing because you have some assurance that different results from different patients for the same test are real and not the result of random differences because each sample was handled or processed differently.”
Certified labs may design, manufacture and use their own tests. Although the FDA has the authority to regulate these lab-developed tests, it generally has not done so as a matter of policy, according to the agency. However, the FDA issued a final rule in 2024 to increase its oversight of lab-developed tests by 2028 to help ensure their safety and efficacy.
Currently, when a lab develops a test without receiving FDA clearance or approval, CLIA prohibits it from releasing any test results without first evaluating the test’s analytical validity, meaning its ability to accurately and reliably detect and measure the biomarkers it is supposed to detect and measure. This validation is limited, however, because it only applies to the conditions present in that specific lab, according to a CLIA fact sheet from CMS.
CLIA regulations do not address the clinical validity of tests, meaning the accuracy with which they identify, measure or predict the presence or absence of a clinical condition or predisposition in a patient. To make a claim of clinical validity, the manufacturer has to submit the test to the FDA for evaluation outside the scope of CLIA, according to the ADA.
“CLIA focuses on the variables of ‘test performance,’ such as lab processes, personnel, quality control, proficiency testing, and quality and accuracy of reporting of results,” Dr. Lingen said. “However, CLIA does not focus on the issue as to whether there is evidence that the results are clinically meaningful, i.e., efficacious/clinically actionable. So, in theory, you can actually have a saliva test that is performed in a CLIA lab that has zero diagnostic accuracy for a specific disease in question.”
The FDA’s role within the CLIA program involves categorizing commercially available tests based on their complexity, which determines the applicable CLIA requirements for performing the tests. Simple tests with little risk of producing an incorrect result are considered to be “waived” tests, meaning the sites that perform them are waived from meeting most CLIA testing requirements. Lab-developed tests, which often rely on high-tech instrumentation and software, default to the high-complexity category, according to the CDC.
When being certified by CMS as part of the CLIA program, labs that only perform waived tests receive a CLIA Certificate of Waiver. These labs must follow the manufacturer’s instructions for the tests but do not need to meet CLIA quality standards, according to the CDC, which develops the standards.
Like labs, health care offices that perform in-office testing are regulated under CLIA, which means dentists who administer waived tests at the point of care need to obtain a waiver certificate for their office, according to guidance from the CDC and CMS on obtaining a certificate. The office requires a certificate regardless of how many tests it performs and whether or not it charges the patient or bills insurance.
Most point-of-care tests are waived. Providers and labs with a waiver certificate must only perform waived tests.
FDA oversight
While several SARS-CoV-2 saliva tests received emergency use authorization from the FDA during the pandemic, the only diagnostic test involving saliva or oral fluids that has received FDA approval is one that detects HIV, Dr. Shi said.
“There are many tools that have been developed in the past 10-plus years,” he said. “The key challenge is still getting through the FDA approval process with proper clinical validation data. I am hopeful as there are various saliva-based new products that are going through the process.”
No saliva tests have been approved by the FDA for evaluating patients’ risk of periodontal disease, dental caries, or head and neck cancer, according to the ADA, but an FDA database shows the agency has cleared saliva tests related to caries risk in the past.
The FDA classifies medical devices as Class I, II or III depending on the level of regulatory control that is necessary to reasonably ensure their safety and effectiveness. Class I devices have the lowest level of risk and are therefore subject to the least regulatory control while Class III devices have the highest level of risk and face the most stringent regulations. Saliva tests can fall into any of these classes depending on their intended use.
All device classes are subject to general controls, such as requiring manufacturers to register with the FDA and provide a list of all their products, banning labeling that is false or misleading, and requiring production methods and facilities to conform to current good manufacturing practices. General controls are the baseline requirements of the Food, Drug and Cosmetic Act, which gives the FDA its authority to regulate medical devices. However, exemptions can apply to these and other device regulations, according to the FDA.
Manufacturers of Class I or II devices are required to submit a 510(k) premarket notification to receive clearance from the FDA to market their devices unless the devices are exempt. A 510(k) must demonstrate the device to be marketed is as safe and effective as, or “substantially equivalent” to, a legally marketed device.
The FDA determines whether the device is as safe and effective as the predicate device by reviewing the scientific methods used to evaluate their differences in technological characteristics and performance data. This performance data can include clinical or nonclinical data, according to the FDA.
“In the FDA clearance paradigm, the applicant does not have to definitively demonstrate efficacy for the new test or device,” Dr. Lingen said. “This is extremely important as the practical real-world implication is that a company can market an FDA-cleared test/device without ever providing definitive peer-reviewed evidence of the diagnostic accuracy of the test being marketed or the claims being made about the product.”
The FDA may also determine a 510(k) is not required to provide reasonable assurance a device is safe and effective, and the device is therefore exempt from the premarket notification process. Most Class I and some Class II devices are exempt, according to the FDA.
Some examples of Class I or II dental products include toothbrushes, which fall under Class I, and dental impression material and curing lights, which are considered part of Class II.
Premarket approval is required for Class III devices, which are devices that sustain or support life, are implanted, or present potential unreasonable risk of illness or injury, according to the FDA.
Premarket approval is the most stringent type of device marketing application required by the FDA. Approval is based on a determination by the FDA that the application contains sufficient valid scientific evidence to ensure the device is safe and effective for its intended use.
“FDA approval is a rigorous process that requires demonstration of both safety and efficacy, typically through multiple phases of clinical trials,” Dr. Lingen said.
Examples of Class III medical devices include pacemakers, cochlear implants and breast implants. The HIV oral fluid test approved by the FDA is also a Class III device because it carries distinct performance considerations and risks as a home-use test, according to the FDA. It is the only home-use HIV diagnostic test approved by the agency, which issued a final rule in 2022 to reclassify other HIV diagnostic tests that are not for home use as Class II devices.
The FDA states there is a unique link between safety and efficacy when it comes to tests since their safety is not generally related to their contact with patients. The agency determines their safety based on the impact of their performance — especially false negative or positive results — on patient health.
At the ADA
Changes related to saliva testing are coming to the CDT Code in 2026.
The Code Maintenance Committee, a standing committee of the ADA Council on Dental Benefit Programs, met in March to accept, revise or decline more than 50 proposed code changes.
One new code approved by the committee addresses point-of-care saliva testing. In the code, “point-of-care” reflects the use of the tests both at dental offices and other care sites such as assisted living facilities.
The committee also voted to amend two existing codes related to saliva testing. The changes reflect the use of the codes for lab-based tests.
In February, the ADA convened leaders in dentistry and medicine for the Oral Cancer Summit, which addressed dental and medical collaboration in the fight against oral cancer. One of the panels discussed saliva tests in development that could potentially help evaluate patients’ risk of head and neck cancer.
“However, as they say, the proof is in the pudding,” said Dr. Lingen, who participated in the summit.
He said the companies need to perform the appropriate studies and publish their results in peer-reviewed journals to demonstrate their tests have sufficient diagnostic accuracy and are therefore valuable to clinicians and patients — which is what FDA approval would require.
“At this time, there is insufficient evidence that any of the salivary oral cancer screening tests have sufficient diagnostic accuracy to be included in everyday clinical practice,” Dr. Lingen said. “I am hopeful that new tests and platforms in the near future will demonstrate sufficient diagnostic accuracy.”
