Dental Hygienists Need to Know About DNA-PCR Tests

Information such as the exact type and concentration of pathogenic periodontal bacteria affecting each case can be summarized, along with specific recommendations for successful treatment planning.

DNA-polymerase chain reaction (DNA-PCR) tests are making impressive inroads into the field of dentistry. Dental professionals can use science down to the DNA level to significantly improve the quality of care provided for patients. The overall impact will be profound.

Two tests launched by OralDNA Labs (Brentwood, TN, USA) require only collection of a patient's saliva sample. The saliva collection process is quickly and easily performed chairside. To collect a saliva sample, patients swish briefly with sterile saline and expectorate into a vial is then shipped to the laboratory. The samples are shipped to the OralDNA laboratory, where they are thoroughly analyzed. A comprehensive report of the analysis is available within four to five business days.

The first test, MyPerioPathSM, identifies the type and quantity of 13 primary bacteria associated with periodontal disease. Knowing the type of bacteria is important. There are three categories of bacteria, the already recognized red complex bacteria, plus are two more categories: orange complex and green complex species.

The orange and red complexes are present in moderate and severe periodontal disease, while the green complex is somewhat less virulent, but plays an important role in assessing the patient's overall periopathogenic burden. Knowing the quantity of each category is important because the presence of these bacteria in the mouth does not necessarily mean that there is active disease. Retesting is essential to determine whether treatment recommendations are working, or to secure a new baseline after a medical event. The first test results should be considered the patient's baseline, to which subsequent test results can be compared.

Periodontal pathogens are opportunistic and strike quickly when a patient's overall health is compromised. Situations that place patients at risk include smoking, emotional or physical stress, hormonal shifts, acute infections, and chronic medical conditions such as diabetes.

The second test available is MyPerioIDsm PST, which begins with the same simple saliva collection system. Its purpose is to determine if a patient is genetically predisposed to periodontal disease. The test looks for specific genetic variations in the patient's DNA associated with interleukin-1 (IL-1) production. The IL-1 polymorphism is found in approximately 30% of the population. People who possess the IL-1 polymorphism are considered to be at greater risk for developing severe periodontal disease than patients who are IL-1 negative.

Human saliva contains two kinds of DNA: human DNA, which comes from white blood cells and epithelial cells that are continually being shed from the oral mucosa and salivary glands, coupled with the DNA of all the bacteria in the mouth. Saliva contains more DNA than blood, as it contains millions of bacteria, each with its own unique DNA profile. Salivary DNA can be analyzed whether the bacteria in it are alive or dead. This is an advantage because there is no need for special handling or immediate sampling analysis, as is required for tests that use living bacteria. In molecular biology, both kinds of DNA can be extracted and analyzed through a laboratory process called PCR.

Reports generated by the tests show in graphic detail the kind and quantity of bacteria that are above the disease-causing threshold. Patients will be able to see a visual representation of the disease-causing organisms in their mouths. The graphic display should motivate patients to comply with the prescribed treatment protocol.

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OralDNA Labs