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Brushing Up on Gum Disease by Steven Shepherd, M.P.H. Getting your teeth pulled because of a sore arm may sound farfetched. But it happened more than once, says Saul Schluger, D.D.S., professor emeritus at the University of Washington's school of dentistry in Seattle. Schluger has been involved in the treatment and study of gum, or periodontal, disease for more than 50 years, and he recalls that the patients in these cases were professional baseball players who had the ill luck to have developed their dental (and arm) problems when the "focal infection" theory of periodontal disease was in vogue earlier this century. The theory held that periodontal disease always worsened, could only be stopped by pulling teeth, and that it could spread--not only from one area of the gums to another, but to other parts of the body. In the case of an affected ballplayer with a sore arm, explains Schluger, it was considered possible that migrating infection from the gums might be the cause of the sore arm. To prevent further problems it was sometimes thought best to simply pull the player's teeth. For ordinary people, a more common scenario was the wholesale pulling of teeth at the first sign of gum disease. The reaction, says Schluger, was "almost Pavlovian. If you had gum disease, you had your teeth out. It was the cause of a lot of dentures." Old Beliefs, New Data Though the focal infection era is now behind us, its legacy remains. Many older people are toothless and wearing dentures for reasons now considered unnecessary. And many fears and beliefs formed during that period continue to hold sway. For instance, periodontal disease is commonly said to be responsible for 70 percent of the teeth lost after childhood. But, according to Brian Burt, Ph.D., a dental epidemiologist in the School of Public Health at the University of Michigan, this oft-repeated statement is based largely on a single study conducted in the early 1950s. A more recent study published in the January 1987 Journal of the American Dental Association found that dental decay was the most common disease-related reason for adult tooth extractions in the late 1970s and early 80s; only 9 percent were necessitated by periodontal disease. Clearly, much has changed. So what is the threat of periodontal disease today? And what can be done about it? What Is Periodontal Disease? In the broadest sense, periodontal disease can be considered any form of ill health affecting the periodontium--the tissues that surround and support the teeth. These include the gums (or gingiva), the bone of the tooth socket, and the periodontal ligament, a thin layer of connective tissue that holds the tooth in its socket and acts as a cushion between tooth and bone. Inflammation or infection of the gums is called gingivitis; that of the bone, periodontitis. These conditions can arise for a variety of reasons. A severe deficiency of vitamin C can lead to scurvy and result in bleeding, spongy gums, and eventual tooth loss. And at least one periodontal disease--the uncommon but highly destructive juvenile periodontitis--is thought to have a strong genetic basis. But as the terms periodontal disease, gingivitis, and periodontitis are most commonly used, they refer to disease that is caused by the buildup of dental plaque. Plaque is a combination of bacteria and sticky bacterial products that forms on the teeth within hours of cleaning. Its source is the natural bacteria in the mouth, of which more than 300 different species have been identified. In small amounts and when newly formed, plaque is invisible and relatively harmless. But when left to accumulate, it increases in volume (in large amounts, plaque can be seen as a soft whitish deposit), and the proportion of harmful species in the plaque grows. Separating Gingivitis The role played by plaque in the development of gingivitis was demonstrated in the early 1960s. Dental researchers had people stop brushing their teeth and let the plaque in their mouths build up. Within two to three weeks signs of inflammation appeared--redness, swelling, and an increased tendency to bleed--and when brushing resumed, the inflammation went away. Gingivitis is fairly common. Just about everybody, says Burt, has it in some degree. A recent nationwide survey by the National Institute of Dental Research, for example, found that 40 to 50 percent of the adults studied had at least one spot on their gums with inflammation that was prone to bleeding. At one time gingivitis and periodontitis were thought to be different phases of the same disease, meaning that the sort of inflammation detected in this study would lead inevitably to periodontitis if left untreated. Yet, dental researchers no longer believe this to be true. In the April 1988 Dental Clinics of North America, National Institute of Dental Research director Harald Loe, D.D.S., describes an ongoing study, then in its 15th year, of Sri Lankan tea workers who practice no oral hygiene. All have gingivitis--but not all have periodontitis. This and other studies with similar results have led dental researchers to two conclusions. One, says dental epidemiologist Ronald J. Hunt, of the College of Dentistry at the University of Iowa, is that "gingivitis is not a particularly serious disease." The other is that "gingivitis and periodontitis are different disease entities." From Periodontitis Some people with gingivitis do, nonetheless, develop periodontitis. The plaque that causes gingivitis is located at or above the gum line and is referred to as supragingival plaque. With time, areas of supragingival plaque can become covered by swollen gum tissue or otherwise spread below the gum line (where it is called subgingival plaque), and in this airless environment the harmful bacteria within the plaque proliferate. These bacteria can injure tissues through the direct secretion of toxins. But they cause the greatest damage by stimulating a chronic inflammatory response in which the body in essence turns on itself, and the periodontal ligament and bone of the tooth socket are broken down and destroyed. This is similar to what happens in rheumatoid arthritis and, like rheumatoid arthritis, periodontitis is now considered primarily an inflammatory disease. The bone destruction from periodontitis can be fairly even, resulting in receding gum lines. But more often it causes deep crevices between an individual tooth and its socket. These crevices are called periodontal pockets, and just as it once was thought that gingivitis inexorably progressed to periodontitis, so it was once believed that shallow periodontal pockets inevitably deepened, eventually becoming deep enough to jeopardize the socket's support of the adjacent tooth. Recently, however, dental researchers have collected substantial evidence to support a theory called the burst hypothesis. This theory states that periodontal bone loss is not a steady process but results instead from periodic flare-ups of infection and inflammatory response inside the pocket. Writing in a 1988 issue of the Journal of Clinical Periodontology, researchers from the British Medical Research Council say this theory helps explain epidemiologic and clinical findings that many, if not most, periodontal pockets are not actively diseased. Rather, they are remnants of past infections that the body has overcome. Further, not all periodontal pockets inevitably deepen; some apparently partially heal and get shallower. What triggers a destructive "burst" inside a periodontal pocket (or, for that matter, the transition from gingivitis to periodontitis) is unknown. But, as described by these British researchers, such events are most likely the result of unfavorable fluctuations in the balance between the type, quantity and location of bacteria in a person's mouth, the ability to resist bacterial infection, and the unique characteristics of an individual's inflammatory response. Good News-Bad News All this has something of a good news-bad news flavor to it. The good news is that most of us have less to fear than we may have been led to believe. Periodontal disease is often described as almost universal--a disease that can or will affect almost everyone and that can have "devastating" results. But most such statements are based on studies that are not only old (dating from the 1950s and early '60s) but that also combine gingivitis and periodontitis under the single heading "periodontal disease." More recent studies suggest that only about 10 percent of adults have periodontitis severe enough to possibly cause tooth loss. The percentage is lower in younger people and higher in older people. Even among these people, says epidemiologist Burt, it is unusual to have more than a few affected teeth. In one 1985 study of nearly 55,000 Italians, among those who had what are considered deep periodontal pockets the average number of affected teeth was fewer than one. The "bad" news generated by all this new research into the causes and natural history of the periodontal diseases (as gingivitis and periodontitis are now referred to collectively) is that while most of us may be at lower risk than previously thought, it is still impossible to say who is at high or low risk individually. It can't be predicted who with gingivitis will develop periodontitis or who with shallow periodontal pockets will go on to develop deep pockets and possibly lose teeth. Researchers are, however, working rapidly on methods to make such predictions. These techniques will involve tests of immune function and the types of bacteria in a person's mouth. Once available, they are expected to dramatically change current approaches to the treatment of periodontitis. Today, periodontitis is treated either by surgically eliminating periodontal pockets or by cleaning affected tooth roots in a process known as scaling and planing. The current trend is towards the latter, and the ability to predict who is susceptible to worsening disease could accelerate the move in this direction. By one estimate, such predictions could make 90 percent of "pocket elimination" surgeries unnecessary. Fighting Plaque As yet, however, dentists can't make such predictions. And because both gingivitis and periodontitis are caused by the buildup of plaque, one dental maxim is as true now as ever: If you want to keep your teeth you have to keep them clean. Only a dentist can diagnose and treat periodontitis. And only a dentist can remove the subgingival plaque responsible for periodontitis and its worsening. Nonetheless, according to Sebastian Ciancio, D.D.S., professor and chairman of the Department of Periodontology at the School of Dental Medicine, State University of New York at Buffalo, controlling the buildup of plaque above the gum line helps control both the quantity and harmful nature of plaque below the gum line. He says an ideal plaque control program involves periodic professional examinations and cleanings--"so you can start out with a clean mouth"--coupled with good cleaning at home. The most effective method of plaque control at home is brushing and flossing. According to dental experts, most people don't brush their teeth properly and frequently miss some areas of their mouths, so it is a good idea to get instructions in effective brushing from a dentist or dental hygienist. One way to help determine how well you are brushing is through the use of disclosing agents (available over-the-counter), which make plaque easier to see. As for toothbrush selection, studies show that soft bristles are better than hard at removing plaque. Toothbrushes are also less effective when splayed or matted and for this reason should be replaced at the first signs of wear. These considerations aside, virtually any toothbrush can be effective if properly used and a choice can usually be made based on personal preference or a dentist's advice. There is a large and growing selection of dental flosses on the market today. According to the August 1989 Consumer Reports, which evaluated "anti-plaque" products, waxed and unwaxed floss are equally effective. Flosses do vary in strength and resistance to shredding, but as long as it doesn't break, the kind of floss you choose is less important than how well you use it--and whether you use it at all. Surveys show that fewer than 20 percent of Americans floss their teeth daily. Though flossing is the only effective way to clean between the teeth, toothpastes can help in the removal of plaque from more accessible tooth surfaces. This is not because they have special "anti-plaque" ingredients, but because they contain abrasives and detergents that aid in the mechanical removal of plaque that occurs during toothbrushing. This is the source of the "anti-plaque" statements made on some toothpaste labels. Several toothpastes are also now being marketed for preventing the buildup of "tartar." Tartar, which is plaque that has calcified and hardened on the teeth, was once thought to contribute to or even cause periodontal disease by physically irritating the periodontal tissues. It is now considered far less important, however, and, according to the January 1988 Journal of the American Dental Association, tartar control toothpastes have a "cosmetic benefit" only. They have no effect on gingivitis or periodontitis. Theoretically, a toothbrush, floss, and toothpaste are all you need to control supragingival plaque. Yet estimates are that only 30 percent of the U.S. population clean their teeth adequately using these mechanical means alone. For this reason, dental researchers have been searching recently for additional ways to help people control plaque. In particular, this search has focused on mouthwashes. There have been differences of opinion over the anti-plaque claims made for various mouthwashes (see "Anti-Plaque Mouthwashes" on page xx). But regardless of how effective a mouthwash might be, Ciancio points out that not everyone needs such products. "People who don't have periodontal problems don't need an anti-plaque mouthwash," he says. "If you are having problems--for instance, gums that bleed when you brush--see your dentist. If an anti-plaque mouthwash is recommended, what I advise is using the product for three to six weeks to see what a clean mouth feels like. Then stop and see if you can maintain that feeling with mechanical means alone. If not, resume the mouthwash for another few weeks, then try again to maintain a clean mouth mechanically." This kind of conscientious effort at good plaque control holds great promise. When combined with researchers' rapidly growing knowledge about the causes of periodontal disease and how it can best be treated, the future offers a realistic prospect, says NIDR's director Loe, that "no one need ever lose a tooth to periodontal disease." Steven Shepherd is a medical writer in San Diego. Periodontal Disease sidebar 1 Anti-Plaque Mouthwashes The use of mouthwashes in the quest for a healthy mouth has a long history. According to Irwin Mandel, D.D.S., professor of dentistry at Columbia University's School of Dental and Oral Surgery, an ancient Chinese text contains the first known recommendation for the use of a mouthwash in the treatment of gum disease: Rinse the mouth with urine. In the intervening 5,000 years, urine (which from a healthy person is sterile) has been used as a mouthwash in cultures around the world. By lowering the acidity of the mouth it may, says Mandel, help reduce the formation of cavities. But against the periodontal diseases it's unlikely to have an effect. The modern era of mouthwashes might be said to have begun in 1920. It was then that Listerine, which had already been sold for more than 40 years as a general antiseptic, was first marketed as a remedy for bad breath. A new advertising campaign for the product introduced the American public to the term "halitosis" and its social undesirability. The pitch was so successful it is now considered a classic. Such promotional activities no doubt contributed to what Mandel describes as a longstanding "disdain" of mouthwashes by members of the dental and scientific communities. This view was further reinforced by a widely held assumption that any effect mouthwashes had against oral bacteria was only temporary. In the early 1980s, however, studies began to appear suggesting that some mouthwashes might indeed reduce supragingival plaque and plaque-related gingivitis. There is no evidence that mouthwashes can affect subgingival plaque or periodontitis. A prescription product (trade name Peridex) containing the antimicrobial chlorhexidine was approved by FDA in 1986 based on studies showing that it reduced gingivitis by up to 41 percent. Chlorhexidine mouthwashes have long been used in Europe, and a 1986 article in The Journal of Periodontal Research called chlorhexidine "the most effective and most thoroughly tested anti-plaque and anti-gingivitis agent known today." A month later the American Dental Association awarded Peridex its "Seal of Acceptance"--the first ever granted a mouthwash by the ADA. This seal (which can have considerable marketing value and is probably most familiar as a result of its being displayed on many brands of toothpaste) indicated that Peridex had met a series of guidelines established by the ADA for evaluating products making anti-plaque, anti-gingivitis claims. In 1987 the ADA awarded its second (and so far only other) Seal of Acceptance to a mouthwash for use in the reduction of plaque and gingivitis. This seal went to Listerine, and its manufacturer has since used the ADA seal in promoting the product as a plaque-fighter. FDA, however, has not yet approved Listerine for this use. In fact, FDA has sent letters to the makers of Listerine and several other over-the-counter (OTC) products making anti-plaque claims stating that in its opinion the products are being marketed in violation of the Federal Food, Drug, and Cosmetic Act and are "at risk of regulatory action." The basis for these letters is that no ingredient for use in an OTC drug product has yet been recognized as safe and effective for the prevention or reduction of plaque or gingivitis in FDA's ongoing evaluation of OTC drug products. FDA therefore considers as unproven claims that a product's ingredients have such effects. In part, the reason for this stance (and for the difference between the actions of FDA and those of the ADA with respect to Listerine) has to do with timing. Data concerning the claims of the OTC anti-plaque, anti-gingivitis products were not available until after FDA's review of OTC dental products was well under way. Such data have since been submitted and in the case of Listerine, says Jeanne Rippere, a microbiologist in FDA's over-the-counter drug evaluation division, the information is probably much the same as that presented to the American Dental Association and on which the awarding of its Seal of Acceptance was based. In a continuation of its ongoing OTC drug review, FDA plans to have a panel of non-government experts evaluate ingredients that might be used in OTC drug products making anti-plaque and anti-gingivitis claims. Steps are being taken to facilitate this process, and it may begin within the next year. n --S.S. Periodontal Disease/sidebar #2 What About Baking Soda? In the late 1970s and early '80s an oral hygiene program known as the Keyes Technique was widely promoted in the United States. Aimed at combatting plaque-related periodontal diseases, the program included not only such conventional advice as frequent professional cleanings, but also the recommendation that patients apply to their gums and brush their teeth with a mixture of salt, hydrogen peroxide, and baking soda. Laboratory studies showing these agents had some effectiveness against harmful bacteria were the principal basis for this recommendation. But critics pointed out that what worked in the laboratory didn't always work in the mouth. A study by the technique's proponents showed some effectiveness in humans. However, it lacked a control group, so it was impossible to say how the technique compared to more traditional methods of oral hygiene. Furthermore, the subjects in this study had been liberally treated with antibiotics, so it wasn't known if the benefits they had experienced were actually due to the baking soda brushing regimen. To resolve these issues, dental researchers at the University of Minnesota, led by Larry Wolff, Ph.D., D.D.S., conducted a four-year study involving 171 adults with moderate periodontitis. The study's design enabled the researchers to compare the effectiveness of a baking soda, salt, and hydrogen peroxide mixture with that of ordinary toothpaste. The results, published in the January 1989 Journal of the American Dental Association, showed that while the baking soda mixture did help in the maintenance of oral health it was no more effective than ordinary toothpaste. Wolff and his colleagues also found that, compared to the patients using ordinary toothpaste, those using the baking soda regimen were three times as likely to stop following their oral hygiene program because it was inconvenient. Overall, they said, there was no evidence that a baking soda brushing regimen "will contribute more toward periodontal health than use of a commercial toothpaste, a toothbrush, and dental floss." n --S.S.