Tooth decay and gum disease are two of the most prevalent public-health problems in the United States. They're both largely preventable. Though dentists and hygienists play crucial roles in prevention, the responsibility for good dental health cannot be left only to the professionals. Diligent care at home—through a conscientious oral-hygiene regimen—is essential. Toothpastes, certain mouth rinses, dental floss, and dental sealants can all contribute to that regimen. Fluoride is most important of all.

Tooth Decay: The Early Problem

Only the common cold is a more prevalent health problem than tooth decay. Dental cavities, or caries (as the disease process is called), afflict about 90 percent of Americans, who endure the dentist's drill for some 200 million fillings annually.

The good news is that the rate of tooth decay among children has dropped sharply in the past two decades. In 1988, the National Institute of Dental Research, a part of the National Institutes of Health (NIH), reported that nearly 50 percent of the nation's schoolchildren have no tooth decay at all—as opposed to an estimated 28 percent in the early 1970s.

Public-health experts report that the majority—up to 90 percent—of dental caries could be avoided with currently available measures. But many people remain unaware of what the most effective measures are, and some dentists still aren't even offering a full range of preventive services.

Preventing Tooth Decay: How Effective Is the Time-Worn Advice?

In the good old days, the road to bristling dental health was seemingly well marked: Brush and floss daily, restrict between-meal sweets, and visit your dentist every six months. That advice still makes good sense, say the experts, but it's not the most effective way to prevent tooth decay.

Brushing and Flossing These are important for removing dental plaque—a thin, sticky, transparent film that forms continually on tooth surfaces. Certain bacteria, especially those on the inner surface of the plaque, produce acids that can attack the tooth enamel. Plaque can also build up over time and harden into a complex material called dental calculus, or tartar. The mixture of deposits can lead to gum disease and tooth loss.

Logically, then, removing plaque daily should prevent tooth decay. "A clean tooth never decays," says an old dental adage. But the question is, "How clean?" The answer, unfortunately, is cleaner than most children and adults are realistically able to achieve.

School-based studies extending for periods of up to three years have examined the effect of thorough plaque removal once a day on the oral health of children. The controlled studies showed that such a regimen is beneficial for preventing gum inflammation but not significantly effective in reducing cavities. These studies and similar research with adults suggest that an even more frequent plaque-removal regimen would be required to reduce caries appreciably—a commitment unlikely to be kept by most adults, let alone by young children and teenagers.

Restricting Sweets Dietary advice about sugar presents a similar confrontation with reality. There's little doubt among dental experts that tooth decay is promoted by frequent consumption of sweets—confections and baked goods—especially between meals (when the sugar is likely to remain longer in the mouth). Sugars of various kinds serve as nutrients for the bacteria in plaque. But years of urging the public to restrict its intake of sugary foods have not countered the effect of the heavy promotion for such foods, and many dental professionals see scant hope of changing the nation's eating habits in that regard.

Moreover, there are sugars in many processed foods that aren't obviously sweet, and in many fruits as well. While cutting out candy bars and cookies can play a part in reducing the risk of developing caries, it's not practical to eliminate all sugars from the diet just to prevent tooth decay.

Regular Dental Visits Since the early 1970s, professional interest in preventive measures has increased. But to some extent, routine dental treatment still consists of treating dental problems rather than preventing them.

Despite the limitations of the traditional approaches to caries prevention, most people accord them high priority. In one typical survey of public perceptions about tooth decay, conducted in Minnesota in 1980, 653 adults were asked what they thought was the best way to avoid getting cavities. Sixty-one percent chose oral-hygiene measures; 15 percent said visiting the dentist; and 12 percent advised avoiding sweets. Only about 1 percent mentioned the use of fluoride (beyond its use in toothpastes). Actually, the use of multiple sources of fluoride—in municipal or school water supplies, in supplements (tablets or drops), or in dentifrices, mouth rinses, and other topical applications—has proved by far the most effective approach to preventing tooth decay.

Since trying to alter the nation's oral-hygiene and eating habits has proved unrealistic, public-health officials have for many years focused their efforts on strengthening the nation's teeth. Specifically, public-health strategy has been to increase the resistance of the tooth itself to decay. In addition to wider use of fluoride, a major recent component of the newer approach is the application of dental sealants—thin watertight coatings that protect vulnerable surfaces of the teeth.

Fluoride: The Best Protection Against Tooth Decay

Fluoride protects teeth in a number of ways, some of which are only partially understood.

One of the initial benefits is its effect on developing teeth. Before the teeth erupt from the gums, fluoride ingested from drinking water or from fluoride supplements is readily incorporated into the tooth enamel. This fluoride-rich enamel increases the tooth's resistance to the acid attack generated by plaque bacteria. Until the early 1970s, many dental scientists thought that the increased resistance conferred during tooth development was fluoride's principal or sole effect. This suggested that fluoride's protective benefits were gained mainly or exclusively during childhood. Since that time, however, research has disclosed that fluoride also acts in other important ways to protect teeth.

Fluoride from drinking water, some toothpastes, or other topical applications is now known to mix with saliva and diffuse into the plaque on teeth. This topical fluoride appears to have two major actions, although the complete process has not been fully sorted out. Tooth decay begins when the acid attack on tooth enamel causes mineral loss of calcium and phosphate. One effect of fluoride is to improve "remineralization" of the enamel by increasing the rate of calcium and phosphate uptake and decreasing the solubility of the enamel, helping to counteract that mineral loss. In another important action, fluoride appears to affect the metabolism of the bacteria, impairing their ability to produce acid from sugars. Both of these effects—strengthening the enamel and inhibiting acid production—benefit adults as well as children.

An additional benefit, which may apply strictly to adults, is the effect fluoride is believed to have in inhibiting the development of surface caries on the root. As age or gum disease causes the gum line to recede, exposed root surfaces become more vulnerable to acid attack. Fluoride is believed to protect the root surface, or cementum, in much the same way it does the enamel.

In short, fluoride is a versatile weapon against tooth decay. Lifelong access to fluoridated drinking water imparts the fullest benefits. Fluoridation of community water supplies, says the U.S. Public Health Service, "can reduce the incidence of dental caries by about 65 percent, reduce the need for multiple-surface fillings, crowns, and extractions, and significantly increase the number of children who are completely free of cavities."

Fluoride and Public Policy

Fluoridation is the most economical way to provide fluoride to everyone. The annual cost of treating a municipal water supply averages about 25 cents a person.

Nevertheless, more than 70 million Americans live in communities that have central water systems but don't fluoridate them. The reasons for opposition to fluoridation are complex. Some people are concerned that fluoridation poses a conflict between the public's interest in dental health and the rights of individuals to choose which risks they will assume. Political opponents of fluoridation often exaggerate the risks, claiming it poses hazards that, in fact, are simply not supported by any credible scientific evidence.

Extensive studies carried out over more than 40 years have established conclusively that fluoridation of community water supplies provides major dental-health benefits and that the procedure is acceptably safe. Numerous studies have found no reliable evidence that fluoridation poses a risk to the public health. Under normal circumstances, the only occasional effect is faint, whitish spotting of the teeth, which is generally visible only to an examining dentist. Public health authorities consider this minor cosmetic risk fully acceptable in light of the benefits of fluoridation. In communities without central water systems, or where fluoridation has not been approved, fluoridation of school water supplies can be an effective and relatively economical alternative for children. Other ways for compensating for the lack of fluoridated drinking water include prescribed dietary supplements during tooth development, professional topical fluoride treatment, and school-based fluoride treatment programs—though some of these measures can be considerably less economical. Even with fluoridated drinking water, topical use of some fluoride toothpastes and mouth rinses can offer added protection.

Cautions About Fluoride

With multiple sources of fluoride available, some caution is necessary to avoid too much of a good thing, especially with young children. While small amounts of fluoride benefit the teeth, prolonged excessive intake can cause undesirable results, ranging from a slight discoloration of the enamel to more serious effects on teeth or bones.

The American Dental Association, for example, advises against giving dietary fluoride supplements to children in communities with fluoridated drinking water or with water supplies that have a natural fluoride content of 0.7 parts per million or higher. Dental experts also recommend that very young children in such communities or those receiving fluoride supplements be taught to limit their use of fluoride dentifrices, since the children may tend to swallow some toothpaste. Once-a-day brushing with a pea-sized quantity or a thin layer of fluoride toothpaste can give adequate protection against tooth decay in such instances. In addition, children under six years old should not use fluoride mouth rinses because they have difficulty rinsing and tend to swallow too much of the liquid.

An important precaution should be followed by kidney patients on dialysis. Since such patients are typically exposed to about 50 to 100 times the amount of fluid consumed by the average person, experts recommend that fluoride—as well as calcium, magnesium, copper, and other trace elements—be removed from tap water before it is used in an artificial kidney machine.

Fluoride does have its limitations. While it reduces the incidence of all types of cavities, it is most effective in preventing those that occur on smooth surfaces, such as the sides of a tooth. It's less effective against cavities that develop on surfaces with pits and fissures, such as the chewing surfaces of the back teeth (molars and premolars). Those surfaces are especially vulnerable to decay because bacteria and food debris can lodge in the tiny pits and fissures.

Over the years, as decay on the smooth surfaces between teeth has approached eradication (in children, at least) tooth decay has increasingly become a pit-and-fissure disease. Fortunately, there's an effective remedy against this type of decay. But it has only recently begun to gain wider acceptance.

Sealing Out Tooth Decay

In 1983, the National Institutes of Health convened a panel of experts in dentistry and public health to evaluate the effectiveness, safety, and use of dental sealants. Ordinarily, such NIH "consensus development conferences" are held to thrash out some reasonable approach to a controversial health issue or practice. In this instance, however, the panel's deliberations and findings were marked by virtual unanimity: Dental sealants, the panel concluded, are a highly effective and safe means of preventing pit-and-fissure caries in children. "Expanding the use of sealants," said the panel, "would substantially reduce the occurrence of dental caries."

Although most people have only recently begun to hear of sealants, these thin, plastic coatings are neither new nor exotic. They were among the first applications of the acid-etching technique now popularly known as "bonding," and some dentists have been placing them on children's teeth for years. What is new is the growing recognition among dentists of the value of sealants. Earlier doubts have been largely dispelled. With improvements in the materials and in application techniques, the sealants work well and offer definite advantages for the patient.

Application of sealants is essentially a painless procedure, requiring no anesthetic or drilling. The chewing surfaces of molars and premolars are the areas commonly sealed, and several teeth may be treated at the same time. The surface is first cleaned thoroughly and then etched with a mild acid solution, which removes an extremely thin layer of enamel and makes the surface more porous and retentive. The sealant is then painted on with a small brush in much the same way that nail polish is applied. Some coatings are formulated to "self-cure," or harden by themselves. Others are cured by exposure to a small beam of visible or ultraviolet light from a hand-operated instrument. In either case, the coatings harden rapidly; the entire procedure takes only about 10 minutes or so.

Once the coating hardens, it effectively seals the enamel from any contact with plaque acids. As long as the sealant remains intact, it completely protects the surface against caries. Clinical studies report that most sealants are retained for several years or longer. Indeed, there are now data on good retention after 10 years. If all or part of the sealant is lost, the tooth can be resealed. Even if a sealant is only partially retained, however, it will still provide some protection.

The prime candidates for sealants are children and, to a lesser extent, teenagers. The teeth commonly recommended for sealant application include the molars of the primary teeth and the newly erupted permanent molars and premolars. Fees for sealants vary widely. In private practice, charges may range anywhere from $10 to more than $35 per tooth.

When sealants were first introduced, they were considered experimental, and most dentists—and dental insurers—kept their distance. In recent years, however, advances in application technique, the emergence of accepted guidelines, and the proven efficacy of sealants have eased earlier concerns about their use. Sealants are now increasingly popular and readily available. There are certainly no longer any valid reasons for delaying their use. Bear in mind, however, that sealants are a supplement to—not a substitute for—fluoride and the other oral hygiene strategies (diligent brushing, flossing, and professional cleanings).

Gum Disease and Plaque

As plaque advances, it initiates periodontal disease, or pyorrhea—more commonly known as gum disease. The film of plaque extends beneath the gum line into the crevices between the gum and the teeth. Gum disease begins when bacteria form and release toxic substances that irritate and damage adjacent gum tissue. This tissue provides support for the teeth, interlocking with the tooth surface to form part of a complex anchoring system.

In response to the release of bacterial toxins, white blood cells move to the site of the irritation through swollen blood vessels. In addition, antibodies and other products of the immune system migrate to the affected tissue. That results in the redness, swelling, and pain characteristic of gingivitis, the initial and most common form of periodontal disease.

Over a period of time, which can vary from a few years to many years, the inflamed and injured gums pull away from the tooth, forming a pocket that accommodates even more bacteria and their products. As the process continues, the pocket deepens and the infection and inflammation spread to the supporting ligament and bone of the tooth socket. At the same time, the gum tissue may recede or begin to lose its grip on the teeth, which may eventually loosen and fall out. What began as gingivitis has now become periodontitis—the condition mainly responsible for at least some missing teeth in countless Americans and total toothlessness in millions more.

Although teeth are usually not lost to periodontal disease until middle age or later, the damage commonly begins many years earlier. One federal health survey found that 39 percent of children between the ages of 6 and 11 have gingivitis to some degree; for youths between 12 and 17, the percentage was 68 percent. Gingivitis would be rather unimportant were it not the root of periodontitis.

It has been estimated that up to 75 percent of Americans have some degree of periodontal disease, but most of them don't know it. The disease is insidious; typically, it causes damage gradually over many years with few signs of its presence. Obvious symptoms such as pain or loose teeth are not evident until the later stages, when much of the supporting tissue has already been destroyed.

Careful daily brushing and flossing can go a long way toward preventing gum disease. No matter how well you brush and floss, however, some plaque will inevitably survive. Plaque, as mentioned earlier, can harden on the teeth to form a rough scale called dental calculus, or tartar. Calculus occurs both on the crown and along the roots of the teeth. Unless calculus is thoroughly removed, its plaque coating will injure surrounding gum tissue. Calculus itself may also be a repository for bacterial toxins.

Neither brushing nor flossing can remove calculus. That's done by an oral hygienist or a dentist, using special instruments to scrape the calculus and plaque remnants from the teeth. An effective oral-hygiene program must include both daily home care and periodic professional cleaning. Two cleanings per year are generally recommended. But if you don't brush or floss conscientiously—or if you form deposits rapidly—you should probably have more frequent professional cleanings.

No checkup is complete unless your dentist examines your teeth and gums for evidence of periodontal disease. This should consist of more than just a visual inspection. In a thorough evaluation, the dentist will poke around each tooth with a thin instrument—a periodontal probe—to check pocket depth, which indicates the degree of tissue destruction and the severity of periodontitis.

Other Factors in Gum Disease

Bacterial plaque is the primary cause of periodontal disease, but other factors can affect its onset or course—for good or for ill. Here are the main ones:

Jaw Configuration A bad bite (malocclusion), clenching or grinding the teeth, or abnormal tooth relationships can put a strain on the periodontal ligaments and supporting bone that hold teeth in place. When periodontal inflammation weakens these tissues, the combined stresses increase the risk of tooth loss. In some cases, adjusting the "bite" through orthodontic treatment can help protect such teeth before they're threatened. Increasingly, adults are wearing braces for this reason, as well as for cosmetic benefit.

Restorative Work Fillings or other restorations, such as crowns, should fit flush with the tooth surface. If they overhang at the gum line, it's difficult to keep the gum areas clean and free of plaque, making them more vulnerable to periodontal disease. Faulty restorations can sometimes be filed down; if not, they may need to be replaced.

Tobacco Smoking damages mouth tissues as well as other parts of the body. People who smoke have greater accumulations of plaque and calculus in their mouth and poorer periodontal health. Tobacco chewing is also associated with poor periodontal health, as well as with other oral diseases, including oral cancer.

Medical Conditions Certain conditions can increase susceptibility to periodontal disease: diabetes and some blood disorders—probably because of lowered resistance to infection; pregnancy—probably because of altered hormone levels; and epilepsy—because phenytoin (Dilantin), the drug most often used to control it, causes overgrowth of gum tissue. Good preventive measures—conscientious home care plus regular professional cleanings—are especially important in these situations.

Fluoride As we have discussed, it's long been established that fluoride in all forms dramatically reduces tooth decay. There are some indications that fluoride can also have a beneficial effect on periodontal disease.

Nutrition Though the foods you eat do not play a major role in periodontal disease, it's probably a good idea to moderate your intake of sweets, especially between meals, since sugar encourages the growth of plaque. Some people believe that high doses of vitamin C are good for the gums, but a study of more than 8500 people found no relationship between the level of vitamin C intake and periodontal disease. Studies in experimental animals, however, indicate that vitamin C may have a subtle effect on tissue resistance to the disease and its progression. The role of other nutrients, such as folic acid, calcium, and phosphorus, is also under investigation.

Treating Gum Disease: Traditional Versus Controversial Techniques

Your dentist may be able to treat periodontitis with techniques known as "deep scaling" and "root planing." These are similar to the scraping away of calculus done in a routine cleaning, except that finer instruments are inserted farther down the side of the tooth beneath the gum margin—if possible, to the infection at the base of the pocket. A single treatment can sharply reduce bacteria levels in the pocket. In addition, scaling scrapes away the diseased gum tissue adjacent to the tooth. Together with planing the root surface, scaling promotes the growth of healthy gum tissue that can often reattach the tooth.

Scaling has long been used in periodontal therapy, both by itself and in preparation for gum surgery. Studies have shown that deep scaling itself can achieve clinical improvement often equal to surgery. These studies have established deep scaling as the preferred procedure for mild to moderate periodontitis. Even some cases of severe periodontitis—routinely treated surgically in the past—may respond quite well to deep scaling alone, when accompanied by effective personal oral hygiene.

In the 10 to 15 percent of periodontitis cases that do reach the severe stage, dentists in general practice often refer patients to periodontists, who have trained for at least two years beyond dental school to specialize in treating periodontal disease.

People often associate "periodontist" with "periodontal surgery." Surgery, periodontists say, is necessary to eliminate pockets that are too deep or too convoluted for a scaler to reach the infection. Surgery is also called for, they say, when the infection involves the area between the roots of multirooted teeth.

But is such surgery always necessary? Since the late 1970s, a great deal of publicity has accompanied a "conservative, nonsurgical" method for treating periodontal disease. This method has generated a major dental controversy. Dr. Paul Keyes, who worked for 27 years at the National Institute of Dental Research, developed the technique while treating cases of severe periodontal disease, some of which had not responded to surgery. Since the disease is caused by bacteria, Keyes reasoned, it should be treated like other bacterial infections—with antibacterial agents rather than with surgery.

Thus was born the Keyes technique. Plaque is scraped from beneath the gum line, and the form and movement of the bacteria are examined under a special microscope. If certain types of bacteria are present, the site that contained the plaque is considered diseased. Treatment then focuses on killing the bacteria in a number of ways short of surgery.

Like other dentists and periodontists, Keyes uses deep scaling. But he also attacks the bacteria through a home-care regimen in which the patient applies common antibacterial agents—hydrogen peroxide, baking soda, and salt solutions—to the pockets between the teeth and the gum. For patients who respond poorly, Keyes prescribes antibiotics such as tetracycline. Surgery is used only when antibacterial measures have failed.

No aspect of the Keyes technique is new, as the originator himself readily concedes. What is new is the use of the technique in severe cases of gum disease that previously would have been referred to a periodontist for surgery. Not surprisingly, perhaps, many periodontists strongly object to the Keyes technique as a substitute for surgery in such severe cases. They consider it clinically unproven and potentially more harmful than helpful.

The Keyes technique has attracted dentists in general practice, and increasingly so as preventive measures reduce the income that they previously derived from drilling and filling decayed teeth. These general dentists are tempted to treat cases of severe gum disease that they might previously have referred to a periodontist for surgery. The approach also has obvious appeal for dental patients. Gum surgery, after all, is expensive. The recovery period can be painful. And surgery sometimes leads to still more dental work for cosmetic reasons. Thus, the Keyes technique is clearly an economic threat to periodontists, who depend on general dentists for referrals.

In opposing the Keyes approach, periodontists argue that you must gain access to an infection before you can treat it. While some periodontists concede that surgery may have been used too liberally in the past, they say that in severe cases surgery is still required to eliminate the protective pockets. With the pockets gone, the patient can keep those particular sites clean and help prevent reinfection. Periodontists point out that surgery has proven itself as a long-lasting treatment, while the Keyes technique hasn't. And today's sophisticated surgical techniques, they say, are less painful and can usually produce more cosmetically pleasing results than in the past.

Dentists who endorse the Keyes technique nevertheless accept surgery as a last resort for those cases that don't respond to the antibacterial treatment.

Though new medical treatments usually undergo extensive clinical scrutiny before they're tried out on the public, the Keyes technique seems to have been a notable exception. Many members of the public, and some dentists, embraced the technique even though it had not yet been thoroughly tested in a scientifically controlled clinical study. In fact, recent studies have shown that the antibacterial agents often employed in the Keyes technique are clinically no more effective than properly performed conventional oral hygiene.

Recommendations

Losing teeth is not inevitable. Personal plaque control and professional cleaning are the keys to success in the prevention of gum disease. The following measures have been proven to be successful:

• Brush and floss every day. Thorough brushing usually takes about three minutes. With practice, flossing can also be completed in about the same time.
• Use disclosing tablets or solutions (once a week is the usual recommendation). These products temporarily color existing plaque and show you where you need to work harder at removing it.
• Have your teeth professionally cleaned at least twice a year—more frequently if you neglect your brushing and flossing.
• At each office visit, your dentist or hygienist should give you a refresher course on proper brushing and flossing. Ask for it if you don't get one. Even better, the dentist or hygienist should hand you a toothbrush and some floss and ask you to demonstrate your skills, so any bad habits can be corrected.
• Don't ignore bleeding gums, which many people consider normal. They are not. If your gums bleed when you brush or floss—or when you don't—you probably have gingivitis, and require professional attention. (Bleeding gums can also be the initial symptom of a bleeding disorder that may require medical investigation.) Note the appearance of your gums. Healthy gums—unless unusually pigmented—should be coral pink. Gums that have a purplish tinge or look puffy are probably inflamed from gingivitis. Other symptoms—persistent bad breath, pus, or teeth that are loose or seem to have shifted position—may indicate severe periodontal disease.

A toothbrush and a length of dental floss are the two most important tools for dental health. Many households add a third tool, the dental irrigator. How effective is it?

According to the Dentist's Desk Reference, published by the American Dental Association, an irrigator is no substitute for the brush and the floss. There is no evidence, the Reference says, that irrigators remove plaque from the teeth or affect the health of the gums.

On the other hand, the jet of water from an irrigator may help clean out food particles and bacterial irritants that brushing misses. And an irrigator may also be useful for cleaning the teeth around crowns, permanent bridgework, or braces.