Moving toward a new kind of dentistry

March 1, 2003
In the infamous scene from the 1976 movie "Marathon Man," the evil antagonist portrayed by Laurence Olivier tortures the innocent Dustin Hoffman character by using dental equipment. The drilling and extracting, detailed in gory close-ups, is preceded by a dental exam in which Olivier hunts for a cavity to serve as a painful target.

Dental medicine is poised to enter a new scientific age of diagnosis and treatment

By Joel Berg, DDS

In the infamous scene from the 1976 movie "Marathon Man," the evil antagonist portrayed by Laurence Olivier tortures the innocent Dustin Hoffman character by using dental equipment. The drilling and extracting, detailed in gory close-ups, is preceded by a dental exam in which Olivier hunts for a cavity to serve as a painful target. While certainly not indicative of a visit to the dentist, the scene does capture a lingering fear of the instrumentation and pain associated with dentistry. Modern methods, including, of course, anesthesia, have changed the course of oral health care in the last century, but it still remains — in popular imagery as well as actual practice — a surgical discipline.

Dentistry is an old profession, emerging in Egypt as early as 2900 B.C. The field has introduced some of the most successful public-health preventive measures, including fluoride treatment and toothpaste to manage dental caries, or tooth decay — not only the most prevalent dental disease but also the disease than affects most humans. Yet the practice remains rooted in surgical intervention, as new methods of exodontia (tooth removal), restorative dentistry and complex surgical procedures continue to evolve. This lag in progression is due to a number of factors including (until recently) a dearth of reliable and accurate methods for diagnosing and monitoring caries, an incomplete understanding of the bacterial environment that gives rise to much of dental disease and a historical separation in the U.S. between the dental profession and the evidence-based methods of general medical practice. This is all poised to change over the next several years.

Grading caries

The basic techniques currently used to diagnose dental caries are more than a century old. These include radiography, visual exam with a mirror and explorer, transillumination and the use of caries- or plaque-detection dyes. Unfortunately, these techniques often cannot identify the caries process at an early enough stage — when remineralizing treatments might have a reversing effect. In fact, most caries remains undetected until it advances to a stage requiring surgical restorative intervention.

Because there is no effective method to observe the development of caries over time, it is defined as a binary process: either it is or is not present. A sophisticated diagnostic approach would provide a scaled assessment of the disease for individual teeth, perhaps from 0 for no caries to 10 for overwhelming disease that has already resulted in a cavity. Such an approach would allow dentists to match treatment to condition, and to monitor disease progression accurately. But first the technology currently available to create such a scale must be refined and broadly adopted in the clinic.

Quantitative light-induced fluorescence (QLF) is a method that may fulfill that goal. The technique, developed in 1994 by the Dutch company Inspektor Research Systems, is an extension of the idea of standard trans-illumination, or shining a light through teeth to evaluate caries. QLF uses high-intensity blue light and computer algorithms to analyze the fluorescence changes that occur in enamel at various phases of demineralization. The method visually highlights the contrast between demineralized and stable enamel, offering more sensitive and quantifiable detection of caries, dental plaque, calculus and staining. The most advanced versions of the device are being used as research tools in approximately 16 centers around the world. The most notable efforts in the U.S. are at the Indiana University School of Dentistry in Indianapolis by George Stookey and at the University of California, San Francisco by John Featherstone. QLF is currently useful to identify early lesions on occlusal, facial and lingual tooth surfaces with high sensitivity and specificity, but not on interproximal surfaces because light cannot reach the obscured contact point between the teeth. The manufacturer has said that it is developing techniques to allow comprehensive tooth surface analysis including interproximal readings. The major barrier to broad adoption, however, remains price. Each unit costs approximately $45,000, much more expensive than equipment currently common to a dental practice such as a drill costing about $1,000 or an X-ray machine, which typically costs $2,000 to $4,000. The pricing trend in technology, however, has traditionally been downward; for example, pulse oximeters, commonly used to measure hemoglobin oxygen saturation in the operating and emergency rooms as well as an oral surgeon's office, went from $50,000 to less than $1,000. Once the technology reaches the point of affordability for the typical dentist, most forms of caries will be diagnosable at a very early stage, when remineralization treatments are effective.

Another interesting approach to the problem of early detection is a diagnostic impression product that 3M ESPE of St. Paul, Minn. says it will soon introduce. The product allows the dental professional to make an impression of the arches with an alginate material containing a reagent; a blue color appears where the reagent reacts with trace amounts of lactic acid. While the technique's value in predicting caries rests on the as-yet-unproven association that lactic acid is present even before demineralization occurs, if proven it could have significant predictive value. Because the product is consumable, the cost should be significantly lower than the cost for QLF.

When a tool such as QLF or 3M's product becomes widely available, it will pave the way for better remineralizing products because the new tools can verify remineralization's effectiveness. How soon this will be adopted for use in the majority of dental offices will depend on the pace at which dentists educate their patients as well as the formula by which dentists will be reimbursed for this new service. Consumers will most likely play a large role in this push toward early-detection devices and development of effective remineralizing agents. When offered the choice, consumers historically have chosen to treat diseases using medicine rather than invasive measures. Examples include the use of antibiotics and cleaning to treat periodontal disease instead of periodontal surgery and the widespread use of cholesterol-lowering drugs to obviate the need for artery-unclogging surgery.

Understanding bacteria

Better diagnostics would also help combat periodontal, or gum, disease. Currently, treatment and management for the expected progress of periodontal disease, though specific to a patient's individual needs, are based heavily on historical data taken from population studies. It is much more difficult to know whether an individual patient's disease will progress. It is difficult to predict the progress of periodontal disease because of the complicated interactions among the patient host, bacterial colonies and other variables such as a person's genetic predetermination and whether he or she has a systemic disease such as diabetes or immunosuppression. Critical to improving such predictions will be a better understanding of the bacterial colonies causing caries and periodontal disease as well as the host response to these bacterial populations.

For years, dental professionals have relentlessly admonished their patients to brush and floss as a major part of oral health maintenance. The desired outcome was removal of plaque and debris, yet this approach, while beneficial, is also incomplete. Recent research has revealed a much more complex plaque bacterial environment, and thus microbial starting point, for dental disease. Understanding and categorizing these varied bacterial matrices, called biofilms, and how they cause caries and periodontal diseases will point the way to more accurate methods of diagnosing the extent of patients' disease. As with caries, a more refined approach at diagnostics will yield better prevention and more targeted treatments. Work being done by James Travis at the University of Georgia in Athens, who characterized the existence and the effects of two cysteine proteases from Porphyromonas gingivalis, and William Costerton at the Center for Biofilm Engineering at Montana State University, Bozeman, is teasing out an understanding of the communication mechanisms within biofilms and between the bacterial colonies and the host response, opening the way for a better understanding of disease progression.

Beyond the mouth

The mouth is intimately related to the rest of the body. For example, xerostomia, or dry mouth, is a side effect of many medications as well as an indicator for a host of hormonal conditions including adrenal dysfunction and menopause. Gingiva marked with fiery red streaks can be the first evidence of certain pediatric leukemias. The 2000 Surgeon General's Report on Oral Health, the first such report, presented evidence of the connections between periodontal disease and the incidence of premature low-birth-weight babies, heart disease and other systemic ills. Steve Offenbacher at the University of North Carolina, Chapel Hill, and Marjorie Jeffcoat of the University of Alabama, Birmingham, are evaluating the possible connection between a mother's periodontal disease and premature low-birth-weight babies. Both researchers are treating periodontal disease in pregnant women to determine if the treatment leads to a reduction in premature babies. James Beck at the University of North Carolina, Chapel Hill, is looking at the link to heart disease. The National Institutes of Health's National Institute of Dental and Craniofacial Research recently funded a multimillion-dollar prospective study at five centers affiliated with either dental or medical schools looking at the heart disease link.

The research, if supportive of these associations, will validate the long-ago-described concept — found in the early 1900 restorative dentistry publications by G.V. Black, a former dean of the now-defunct Northwestern Dental School — that the mouth as a portal to the body is important not only for oral care's sake but also for the sake of total health. Linking oral health to the wider arena of overall health care provides a push to adopt the evidence-based model pervasive in general medicine. As a case in point, several decades ago cholesterol level was not known to be a strong risk factor for heart diseases. Now that a significant link has been established and preventive medications to lower cholesterol developed, many patients know their cholesterol level. Similarly, if oral disease is shown to predict systemic diseases tied to serious health problems and death, the push will be on by academic, government and company researchers to discover better diagnostics and treatments, such as sampling of sulcular fluid (oral fluids mixed with periodontium exudate) for inflammatory mediators such as interleukins associated with periodontal and heart disease risk.

The greater understanding at all levels of the origins and impact of dental disease will hasten the introduction of diagnostic technology allowing subclassification of dental disease, and the subsequent ability to offer noninvasive and stage-specific treatment. A new, non-surgically focused dentistry will emerge, addressing oral disease in the way that the X-ray and microbiology transformed medicine from a practice of alleviating symptoms to one treating and preventing underlying disease.

Note: This article reprinted with Permission. Copyright© 2002 by Scientific American, Inc. All rights reserved. To order the original magazine where this article appears, "Emerging Trends In Oral Care — The Biofilm Revolution," contact Philips Oral Healthcare, the makers of Sonicare®, at (877) 676-7664.

Dr. Joel Berg is president of the American Academy of Pediatric Dentistry Foundation. He is vice president of clinical affairs at Philips Oral Healthcare. He can be reached by e-mail at [email protected].

Dateline: Dentistry

Dip wool in honey and rub teeth. Follow by rinsing with a mixture of dill, aniseed, myrrh, and white wine.

Hippocrates' 400 B.C. advice for cleaning teeth has, of course, been eclipsed by methods with more effective track records. But Hippocrates' admonition and other civilizations' treatments before him are evidence of the ancient roots and importance placed on dentistry. The profession continues to evolve in significant ways. New treatments and technology continue to emerge from greater scientific understanding of the processes causing dental disease, and this continues to shape in interesting ways how the several-thousand-year-old enterprise is practiced.

Actions of sugar on the teeth

October 11, 1856

The Charleston, S.C., Medical Journal states that M. Larez, in the course of his investigations on the teeth, arrived at the following conclusions:

1st. Refined sugar, from either cane or beets, is injurious to healthy teeth, either by immediate contact with these organs or by the gas developed, owing to its stoppage in the stomach.

2nd. If a tooth is macerated in a saturated solution of sugar, it is so much altered in the chemical composition that it becomes gelatinous, and its enamel opaque, spongy, and easily broken.

3rd. This modification is due, not to free acid, but to a tendency of sugar to combine with the calcareous basis of the tooth.

The foregoing conclusions are correct, and candies and condiments should be avoided. They should be kept from children especially.

From the pages of Scientific American