Saliva: Of Emerging Importance in the Medical and Dental Worlds
Diagnostic tools provide unlimited details about oral systemic health.
by Amy Nieves, RDH, and Wendy Fitzgerel-Blue, RDH, BSDH
Saliva is the body's natural defense for the oral cavity. Saliva plays a key role in lubrication and remineralization and demineralization stages throughout the day. Composition of saliva, its buffering capacity, and the antimicrobial properties can be factors in the relationship to caries. Antimicrobial factors and the buffering components of saliva can protect tooth enamel from cariogenic microorganisms.1
Immunoglobulins (secretory IgA) are a type of antibody secreted from the parotid gland. They are known to inhibit adherance of some strains of streptococci to oral mucosa. This enables the microorganism to be easily flushed away and swallowed.2,3 Proteins such as lactoferrin, lysozyme, peroxidase, defensins, and histatins that are found in saliva can kill or inhibit the growth and metabolism of microorganisms in the oral cavity. Saliva proteins also maintain balance of the health of the oral cavity.3 According to Dr. John D.B. Featherstone, "Understanding the role of saliva in maintaining health, as well as its relation to oral disease, is vital to the competent dental practitioner."4 Systemic factors that can affect the composition of saliva are salivary gland pathology, chronic renal failure, drug abuse, menopausal and hormonal effects, as well as side effects from medications.
There are two different methods of saliva testing available to the dental industry — oral environment testing (GC America, Inc.'s Saliva Check and Ivoclar CRT® Buffer test) and pathogen specific testing. Oral environment testing is typically done chairside, taking 10 to 15 minutes and yielding immediate results. Evaluating the oral environment should include the assessment of both stimulated and unstimulated saliva pH, consistency of saliva, the quantity or flow production, and the buffering capacity of saliva.
Pathogen specific tests require saliva sample collection and incubation for 48 hours before results can be assessed. With both types of tests, it is important to understand composition can vary dependent upon time of day saliva is collected, the flow rate, how it is stimulated, and the duration of stimulation. Ideally, testing should be done in the morning hours and patients should not eat or drink for a minimum of an hour before the test.
Some controversy exists for pathogen specific testing due to clinical limitations of expense and incubation time constraints. Results can be recognized as subjective or only semiquantitative. It is also of utmost importance that the interpretation of these results be evaluated by a trained dental professional. Research and development divisions of several manufacturers claim a new generation of pathogen specific tests will be available in the market soon. This new generation of tests promises to deliver chairside results at less expense.3
Today's pathogen specific saliva testing monitors the level of certain bacteria in the oral cavity. The Ivoclar CRT® bacteria test detects the level of Streptococcus mutans and lactobacilli in saliva.5 Both of these bacterial types play a key role in the caries disease process. Oratec Corporation has developed BANA plaque microbiological testing after 15 years of research and 50 published papers. The BANA Test is a modification of the BANA hydrolysis test developed by Dr. Walter Loesche and colleagues at the University of Michigan School of Dentistry. It exploits an unusual enzyme found in Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus, three anaerobic bacteria highly associated with adult periodontitis.6
Confirmation of a high level of acidogenic bacteria such as s. mutans or lactobacilli would aid as a diagnostic and educational tool in the development of a caries management protocol. It also contributes in the implementation of an antimicrobial therapy along with the addition of xylitol, fluoride, ACP, and products that contain Recaldent™(GC America, Inc.'s MI Paste and MI Paste Plus and Trident White® gum).
Salivary Flow Dysfunction
The flow rate is the most familiar saliva dysfunction to the dental professional. Resting saliva arises 60 percent from submandibular glands, 5 percent from sublingual glands, 20 percent from parotid glands, and 15 percent from the minor salivary glands. It is important to evaluate both stimulated and unstimulated saliva. Abnormal stimulated saliva can be an indication of saliva gland pathology, Sjogren's syndrome, or even HIV.1
Salivary flow dysfunction is a common problem and is frequently undiagnosed because the patient's symptoms, which the patient may not notice, can be a perceived feeling and not a reliable indicator of salivary gland production. Symptoms can be subjective as it is common for patients to be unaware of diminished salivary production until the resting flow rate is less than half of normal. This is known as xerostomia. Without diagnostic testing, the clinician also may not be aware of true dysfunction until it is severe.1
The lack of saliva production can also affect an individual"s quality of life. Nutritional deficiencies may start to appear due to the effects of dry mouth. The effects of dry mouth may inhibit a patient"s consumption of certain foods and may require drinking more water to be able to swallow food. It may take the patient longer to eat. It is common for patients with a quantity dysfunction to suffer poor sleeping patterns. Sleep is interrupted several times a night with the discomfort of mucosa "sticking" to teeth or the tongue "sticking" to the palate.
Unstimulated salivary flow rate and buffering capacity have also been directly associated with dental erosion. Dental erosion can have a symptom of hypersensitivity. Decreased unstimulated salivary flow can also lead to a lower pH level in the mouth and a higher number of acidogenic bacteria in saliva and plaque.7
Checking for the consistency of saliva is important as well. Saliva is naturally composed of 90 percent water and should look like water. Clinical signs of saliva dysfunction include increased saliva viscosity, sublingual pooling, the tongue may be coated, or dry mucous strands may be present.8 The presence of poorly mineralized calculus or even the absence of calculus may be another clue to saliva dysfunction.1 A patient may also lose interest in eating due to how uncomfortable it is to eat without saliva, which can result in nutritional deficiencies.3
Saliva is not naturally acidic on its own. It may become acidic due to food, beverages or acidogenic microorganisms within the oral cavity. Checking the unstimulated pH level of a patient"s saliva allows a general assessment of the acid level of the oral environment. Healthy pH ranges between 6.7 and 7.4.1 The degree to which the pH will drop is influenced by the amount and location of plaque, the prevalent flora, salivary production, and the type and concentration of the substrate (fermentable carbohydrates) introduced into the environment.2
Critical pH is the point at which enamel will start to dissolve. Hydroxyapatite will start to dissolve when the pH level in the mouth reaches 5.5. 7 Fluorapatite will resist that acid challenge further as it will start to dissolve when the pH level in the mouth reaches 4.5.1 Critical pH can also be reached when saliva is inadequate in the levels of bicarbonate of calcium and phosphate. A patient without saliva dysfunction should be able to rebound the pH drop and increase or neutralize the plaque pH through increasing saliva flow. As the flow rate increases, so too should the saliva's bicarbonate concentration and production.2
Salivary flow is naturally stimulated by taste and mastication of food. Therapies involving chewing gum, especially those containing xylitol or Recaldent™ (CPP-ACP), can greatly enhance the rise of the pH level in the mouth.4 Xylitol will further aid in the reduction of the bacteria in the mouth. Trident White® gum, with .6 percent Recaldent™, will buffer the acid produced by the bacteria. For those with TMJ issues, xylitol is also available in mints, candies, and breath sprays. Increased salivary flow rate contributes to the increased level of pH in the mouth by the physical cleansing of the saliva and can increase the level of bicarbonate concentration. These factors contribute to enhanced remineralization throughout the day. Normal saliva production should measure between 1.0 – 1.5 liters per day.1
Measuring Health Through Saliva
Accessing the buffering capacity of saliva is key in the role of remineralization and demineralization stages that naturally occur in the oral cavity. Measuring the saliva's buffering capacity yields valuable insight as to the ability of an individual's saliva to minimize an acid challenge. Healthy salivary glands produce bicarbonates that aid in the buffering or neutralizing of plaque and dietary acids. Neutralizing plaque and dietary acid suppresses aciduric organisms which then depresses demineralization. Poor results from a salivary buffering test can be a valid predictor that the demineralization stages will outweigh the remineralization stages and dramatically increase the individual's risk for caries.1
Oral cancer is on the rise in this country. Saliva testing can be used to access a patient"s risk for oral cancer. Most oral cancers are not diagnosed until a dentist or dental hygienist sees a lesion in the office. UCLA has developed a diagnostic test with saliva that can predict oral cancer before symptoms start to appear in the oral cavity. The Oral Fluidic Nanosensor Test (OFNASET), analyzes saliva for cancer biomarkers. According to GeneFluidics, Inc., the OFNASET analyzes saliva for the presence of four salivary mRNA biomarkers (SAT, ODZ, IL-8, and IL-1b) and two salivary proteomic biomarkers (thioredoxin and IL-8). This diagnostic test in trials has been 82 percent accurate in clinical trials.9
Not only is saliva testing for dental professionals to assess risk and diagnose different dental diseases, but it's also for the medical professional to aid in the diagnosis of risk factors for systemic diseases. According to William Dubinsky, PhD, a biochemist and professor of integrative biology and pharmacology at the University of Texas Medical School at Houston, "Saliva is a complex mixture of proteins. We go through a process that compares different samples by chemically labeling them in such a way that we can not only identify the protein, but determine how much of it is in each sample," said Dubinsky. "This allows us to compare the levels of 150 to 200 different proteins in cancerous versus noncancerous specimens to identify possible markers for disease."10 Saliva tests can also be used to aid in the diagnosis of such systemic diseases as Sjogren's syndrome, alcoholic cirrhosis, cystic fibrosis, sarcoidosis, diabetes mellitus, and adrenal cortex diseases.3 Microbiological testing of saliva can test DNA for detection in viruses such as the herpes virus associated with Kaposi"s sarcoma and HIV.3,11
Researchers are investigating salivary testing for autoimmune disorders such as Sjogren's syndrome. Studies have shown that 87 proteins measured in serum and 75 proteins analyzed in saliva can be an indicator of Sjogren's syndrome.11 According to another study, saliva one day may replace blood in monitoring nutritional deficiencies in geriatric patients.11
According to the American Cancer Society, breast cancer is the leading cause of cancer death in women worldwide. In February of 2008, there were numerous news reports across the country about scientists developing a salivary test for women at risk for breast cancer. Dr. Charles Streckfus, a professor of diagnostic sciences at the University of Texas Dental Branch in Houston, states that he feels a salivary test to predict breast cancer will be approved by the government for use within five years and that a test can be developed that a dentist can use in the operatory. "Why not the dentist?" said Streckfus. "Most folks, especially women and children, visit the dental office more often than they ever see the physician. Saliva is a noninvasive, quicker way for detection."9 During research, this test identified 49 proteins in saliva that distinguishes healthy women from those who are at risk for breast cancer. Breast cancer changes the type and amount of proteins in secretions from salivary glands. According to the same article, other researchers are developing a saliva test that would access risk for ovarian, endometrial, cervical, and head and neck cancers as well.10
Catherine M. Flaitz, DDS, dean of the University of Texas Dental Branch in Houston, states, "We have a special opportunity to collaborate with some of the most talented clinicians and scientists within the world"s largest medical center to evaluate the significance of oral biomarkers for predicting health and disease. It is such a rewarding time to be a part of this great profession."10 The competent dental professional must remain educated on the importance of noninvasive salivary testing. New research is contributing to the development of new testing that will not only predict dental diseases, but will also aid in diagnosis and monitoring of general health and systemic diseases. Salivary testing continues to be developed through research and is an important asset to assessing a patient"s risk for dental and medical disease.
References
1 Graham I, Mount WH. (2005). Preservation and Restoration of Tooth Structure. 2nd Edition. Queensland, Australia: Knowledge Books and Software.
2 Newbrun E. (1989). Cariology, Third Edition. IL: Quintessence books.
3 Herenia P, Lawrence DM. (2002 Vol.68, No. 3, March). Salivary Markers of Systemic Disease: Noninvasive Diagnosis of Disease and Monitoring of General Health. Retrieved February 29, 2008, from Journal de l"Association dentaire canadienne: http://www.cda-adc.ca/jadc/vol-68/issue-3/170.pdf
4 Featherstone J. (2004). The Continuum of Dental Caries – Evidence for a Dynamic Disease Process., Journal of Dental Research 83 (Special Issue C) , C39-C42.
5 Ivoclar Vivadent - CRT bacteria. (n.d.). Retrieved February 29, 2008, from Ivoclar Vivadent: http://www.ivoclarvivadent.com/content/products/detail.aspx?id=prd_t1_1471309891&product=CRT+bacteria.
6 Oratec. (n.d.). Retrieved February 29, 2008, from https://www.oratec.net/category.asp?catid=13.
7 Meurman JH, ten Gate JM. (1996) Pathogenesis and modifying factors of dental erosion European Journal of Oral Sciences 104 (2) , 199–206 doi.
8 Young DA, Treating Caries Chemically: Fact or Fiction. Academy of Dental Therapeutics and A. 2006, Retrieved August 6, 2007 from: http://www.ineedce.com/pdf_files/adts_treating_caries_chemically.pdf.
9 Gau V, (2007, March). Oral fluid nanosensor test (OFNASET) with advanced electrochemical-based molecular analysis platform. Annals of the New York Academy of Sciences , pp. 401-10.
10 Saliva Test To Detect Breast Cancer Could Be Done By Dentist, Study Suggests. Retrieved February 29, 2008, from Science Daily (2008, January 11): http://www.sciencedaily.com/releases/2008/01/080110123921.htm.
11 Delaleu N, (2008 Feb 20;10(1)). Biomarker profiles in serum and saliva of experimental Sjogren"s syndrome - associations with specific autoimmune manifestations. Arthritis research & therapy , R22.
About the Authors
Amy Nieves, RDH, is a Mentor of the Year (2003) and Award of Excellence (2004) winner. She graduated in 1999 from Middlesex County College in Edison, NJ. She presently is the Southern MI Specialist for GC America, Inc. In 1999, she started what was to become the most widely read dental hygiene Internet community, which has more than 3,700 members. Visit her Web site www.amyrdh.com for more information. In 2004, she co-authored the book "The Purple Guide: Developing Your Clinical Dental Hygiene Career" with Shirley Gutkowski, RDH.
Wendy Fitzgerel-Blue, RDH, BSDH, is a graduate from the University of Missouri-Kansas City dental hygiene program in 1997. She has more than 18 years of progressive dental experience. She presents educational seminars nationwide to dental and dental hygiene schools, local and state dental hygiene components, study clubs, and state dental associations. She is a regular participant in "Give Kids a Smile" programs in St. Louis, Mo., and in Quincy, Ill. She was an integral part of introducing and facilitating glass ionomer as the material of choice for these sealant programs. Wendy is the Senior MI Specialist for GC America, Inc. She is the recipient of the 2005-2006 JJ. Nevin award for Rookie of the Year and the Toshio Nakao award for overall achievement.
