by Lynne H. Slim RDH, BSDH, MSDH
With the graying of America, many Baby Boomers and Generation X hygienists are facing unprecedented challenges — how to make decisions about aging parents and other loved ones with various forms of dementia. Researchers are busy studying biochemical brain alterations in elderly people, and they recently discovered biochemical alterations in cerebrospinal fluid (CSF). Impressive efforts have been made to develop biomarkers for the pathogenic processes of Alzheimer's disease that can be used someday as diagnostic tools. Focus is on patients with mild cognitive impairment (early in the disease process) that is not severe enough to fulfill criteria for dementia but early enough before the neurodegenerative process is too severe. Eventually, CSF biomarkers of this type may be useful in identifying study populations for clinical trials of Alzheimer's disease patients.
What are biomarkers, and do we have any for periodontal diseases?
A biomarker is a substance used as an indicator of a biologic state. It may be measured and evaluated as an indicator of normal or pathogenic biologic processes, or pharmacologic responses to a therapeutic intervention. Traditional biomarkers in medicine include heart rate, blood pressure, imaging (such as mammograms or chest X-rays), and the prostate-specific screening antigen test (PSA) for prostate cancer.
A traditional biomarker for periodontal disease is bleeding on probing (BOP), and it's still viewed as the best disease predictor available today.1 Researchers report that there are many false positives associated with it, but the absence of BOP is considered a very precise negative predictor of disease activity.1
Periodontal diagnosis is based upon subjective clinical examination procedures that are time-consuming and poorly implemented by hygienists and dentists.2 Oftentimes, hygienists and dentists base a diagnosis solely on periodontal probing measurements due to time constraints. Underdiagnosis of periodontal disease results in significant amounts of untreated disease and low rates of appropriate therapeutic intervention.
Chronic periodontitis is now considered a site-specific disease, but what has continued to puzzle periodontal researchers is the unpredictability of the disease at a patient and site-level. As a result, a flurry of research activity was underway in the 1990s to study the utility and value of individual biomarkers of periodontal disease activity, measured within gingival crevicular fluid.2
Researchers created biomarkers that indicated the presence or absence of periodontal pathogens, gingival and periodontal inflammation, the host inflammatory-immune response to certain pathogenic species, and host tissue destruction. The biological media of choice included saliva, serum, subgingival plaque, tissue biopsies, and gingival crevicular fluid. As a result, and after many biomarkers and diagnostic tests were developed, a number of diagnostic kits became available. These kits included biomarkers within gingival crevicular fluid, but market research wasn't performed and the kits failed to reach the practice community.2 Chapple reports the following problems with these kits:
- They were too time-consuming and complex to perform.
- Dentists and patients didn't understand the meaning of the results.
- Kits were site-specific and site selection was problematic.
- Results didn't impact therapeutic intervention.
- Kits were too costly for routine use.2
Saliva is now being looked at as another choice for an appropriate diagnostic medium and one that can be used by both medical and dental teams. The challenges are enormous, because it still isn't known what the exact phenomena are that trigger the cascade of events leading to tissue destruction, and a biomarker needs to predict disease onset and progression.1 It's possible that the markers associated with inflammation are not the ones responsible for initiating the disease process.1 It's also possible that markers that characterize the inflammatory process in gingivitis are different from those that develop in periodontitis.1
Since periodontitis is a multifactorial disease that includes initiation by bacteria and host interaction, it's unlikely that a single biomarker will be able to predict periodontal disease activity. A combination of biomarkers may emerge eventually, and in the meantime, risk assessment is more meaningful than simple clinical measures such as periodontal probing.
The National Institute of Dental and Craniofacial Research (NIDCR) strategic plan for 2009-2013 contains a diverse portfolio of research that includes innovation in the area of salivary diagnostics. One technology of interest to hygienists is called the oral fluid nanosensortTest (OFNASET), which was designed for point-of-care detection of salivary biomarkers for oral cancer. It is a handheld, easy-to-use system that can be used in a medical or dental practice for point-of-care disease screening and detection.
Picture your future comprehensive periodontal exam in this way: risk assessment software and the use of a handheld device that measures biomarkers such as MMP-8 and C-reactive protein. Measurements from that notched metal stick might end up taking a back seat to new diagnostic technologies.
- Zhang L et al. The clinical value of salivary biomarkers for periodontal disease. Periodontology 2000; 2009: 51:25-37.
- Chapple I. Periodontal diagnosis and treatment — where does the future lie? Periodontology 2000; 2009: 51:9-24.
About the Author
Lynne Slim, RDH, BSDH, MSDH, is an award-winning writer who has published extensively in dental/dental hygiene journals. Lynne is the CEO of Perio C Dent, a dental practice management company that specializes in the incorporation of conservative periodontal therapy into the hygiene department of dental practices. Lynne is also the owner and moderator of the periotherapist yahoo group: www.yahoogroups.com/group/periotherapist. In addition, Lynne is the editor of the Sunstar Americas e-newsletter “The GUMline.” Lynne speaks on the topic of conservative periodontal therapy and other dental hygiene-related topics. She can be reached at [email protected] or www.periocdent.com.