Global Health Nexus (GHN): In April 2005, The New York Times Science section published an interview with you entitled A Bloodless Revolution: Spit Will Tell Us What Ails You, in which you predicted that saliva tests would become the gold standard for gauging disease. What is the current state-of-the-art with regard to using saliva to diagnose disease?
Dr. Wong: Saliva diagnostics continues to gain momentum on two fronts: scientific and clinical. At the scientific level, we now have two diagnostic alphabets for saliva, the proteome and the transcriptome. NIDCR-funded research has led to the identification of 1,166 proteins in parotid, submandibular, and sublingual fluids. We also know that there are 185 mRNAs present in the saliva of all healthy individuals. These two salivary diagnostic alphabets allow scientists to systemically examine and harness the combination of diagnostic proteins and RNAs that constitute the diagnostic signature or fingerprint of a disease in saliva.
On the clinical front, there is a lot of activity as well. Use of saliva for gauging oral diseases such as caries risk assessment and periodontal disease are much talked about and clinical tests are actually in the pipeline. Of special note is the use of saliva for oral cancer detection. Using the proteomic and transcriptomic alphabets, we have identified a small panel of salivary proteins and RNAs that can detect oral cancer with great clinical accuracy (>90%). This test is now being rigorously validated in preparation for clinical utilization within two years.
Perhaps the most exciting question in salivary diagnostics is: Can it be used to detect systemic disease? Although critical review of the current data does not at this time support the claim that saliva diagnostics cross over to systemic disease, I predict that we will see credible scientific support for this claim within the next two years.
GHN: Given these advances, do you think that salivary diagnostics will become the norm in dental offices?
Dr. Wong: Three things need to occur and converge for this to happen. First and foremost, there must be credible science documenting the effectiveness of the saliva diagnostic test, from laboratory discovery to clinical validation and FDA approval. Second, industry must become interested in marketing the technology. Third, the procedure must be reimbursable by CMS or third-party payers. Only when these three elements align and converge can a particular saliva diagnostic test become the norm in the dental office, or in any healthcare provider’s office. There is no particular reason why dentists should do this on their own, as there are no reimbursement codes or validated clinical tests at this time. But that is changing rapidly as the science, the commercial interest, and the professional organizations, such as the ADA, ADEA, and AADR, begin to focus attention on this emerging portfolio.
GHN: If dentists begin using salivary diagnostics in their offices, what impact do you think it will have on the public’s perception of the dental profession?
Dr. Wong: A very good one. The public as well as the profession needs to be educated on this topic. This will likely happen through a combination of efforts by commercial vendors, consumer advocates, governmental agencies, and professional organizations. Because saliva is an ideal biofluid for disease screening, dentists are especially well positioned to screen patients for potential life-threatening diseases during routine office visits. Saliva has all the desirable features of a screen fluid, plus high patient compliance, and is easily accessible and inexpensive. Moreover, it can be self-obtained, and does not require trained personnel. All of these advantages make saliva an economically feasible biofluid to be used for clinical screening applications.
The use of salivary diagnostics in dental offices would create a model to permit early screening for the presence of systemic diseases, followed by a referral to the appropriate physician for definitive diagnosis, thus creating a closer working relationship between physicians and dentists. And when the public realizes that the value of a dental visit extends beyond oral health to systemic health surveillance, the image of the dentist as a diagnostician will be positively impacted.
GHN: Should salivary diagnostics be taught in the predoctoral curriculum? Should it be taught in CDE courses?
Dr. Wong: Both should, will, and must happen. Dental students and dentists do not have to be persuaded about the value of salivary diagnostics. What they need is the training to understand the science and foundation of this emerging discipline.
GHN: Do you think that in the future we will see salivary diagnostics as a mandatory, four-year curriculum in dental education?
Dr. Wong: I certainly hope so. We have just finished planning for such a curriculum at UCLA at both the predoctoral and postgraduate levels. This was actually initiated by the students. I am very excited to be coordinating these courses.
GHN: As you know, the theme of this issue of Global Health Nexus is Educating Men and Women of Science, with the emphasis on educating men and women to be sophisticated consumers of research. Do you think that the ability to use saliva diagnostics will become one criterion by which to judge if a dentist is a man or women of science?
Dr. Wong: Yes and no. Only if dentists invest the necessary time to understand the scientific rationale for salivary diagnostics, and become convinced by it, can they determine if this technology is of value to their practices. The ability and the desire to want to understand is key to scientific curiosity, the essence of being a man or woman of science. To use the technology without having critically evaluated the scientific literature would be incompatible with being a man or woman of science.