Dental Health : How Decay Occurs

by Food and Drug Administration (FDA)

(Page 3 of 3)

Although excess fluoride intake can be toxic, most reported adverse reactions involve vomiting, diarrhea and eye irritation. Because fluoride is a drug, FDA requires toothpaste manufacturers to include on the labels of fluoride toothpastes a warning that the products should be kept out of the reach of children under 6. In addition, because FDA requires all over-the-counter oral drugs to bear an accidental-ingestion warning, toothpaste labels also must carry a warning that instructs consumers to contact a professional or a Poison Control Center if more than the normal amount used for brushing is swallowed. This labeling requirement took effect April 1997.

Another highly effective way to prevent cavities is sealants. Plastic material that is usually applied to the chewing surfaces of the permanent back teeth, sealants bond into the depressions and grooves of the chewing surfaces, acting as a barrier to plaque and acid.

According to the American Dental Association (ADA), sealants are "virtually 100-percent effective at preventing tooth decay." They can be used on the permanent teeth of both children and adults.

Though sealants are considered to be most beneficial to children, a 1996 study published in ADA's journal found that only 20 percent of school-aged children have dental sealants on their permanent molars. Cost-wise, sealants average about half the cost of a filling, according to the American Academy of Pediatric Dentistry.

Another reason for the decline in dental caries can be attributed to public education aimed at encouraging consumers to follow good oral health practices at home and see a dentist regularly, beginning as early as age 1.

"Most patients now know [they should] see a dentist regularly," says Cleveland dentist Matthew Mecini, D.D.S., citing statistics that show that 50 to 55 percent of adults actually follow that advice. "We [the dental community] are doing a better job of educating the public on the need for regular dental care."

What's Ahead

Efforts to reduce cavities don't end there. One of the most promising preventives on the horizon is a vaccine-like product against decay. In April 1998, British scientists reported that they had developed a plant-based treatment, which, when applied to the teeth, effectively prevented Streptococcus bacteria, the main bacteria involved in tooth decay in humans, from growing in the mouth for up to four months.

In the United States, researchers funded by the National Institute of Dental and Craniofacial Research are studying a similar preventive, known as "plantibodies." Using genetic engineering techniques, scientists transfer a gene for antibodies specific for streptococci to the tobacco plant, which produces large quantities of these antibodies. Antibodies purified from the tobacco plant are then applied to the teeth with a goal of preventing streptococci from adhering to the teeth.

"The concept is good," Mangan says, but notes that the high cost of genetic engineering and the bother of applying the substance on a routine schedule may make the product somewhat impractical.

Other research, he says, focuses on a vaccine that boosts children's immune systems to prevent decay. The intent of this experimental product is to stimulate the body's own production of antibodies to prevent streptococci from adhering to the teeth.

While these experimental products promise an even brighter dental outlook for future generations, kids today can look forward to a life of dental care that even their parents never envisioned.

"If you can reduce the anxiety that often accompanies dental treatment," FDA's Runner says, "that's a very positive step, especially for children. That's where a lot of these devices have the most potential — in children."

How Decay Occurs

For most people, the first sign of a cavity is pain, but the actual start of tooth decay begins much earlier, with the accumulation of minute amounts of a sticky film, called plaque, on the tooth's surface.

Plaque contains bacteria, which feed on carbohydrates in the mouth. As a result of their feeding frenzy, the bacteria produce acids, which can attack the tooth enamel — the outermost layer of the tooth. If the plaque isn't removed, it continues to build, creating more acid that continues to damage the tooth enamel. There usually is no pain until the acids eat through to the tooth's underlying dentin and pulp layers, where the nerves are located. This decay, technically known as dental caries, is the point at which treatment is needed to prevent further tooth damage and loss.

Cavities usually form:

• in depressions and grooves of chewing surfaces
• between teeth
• on the root surfaces of people whose gums have receded.

Dental decay usually occurs in the back teeth, where it is more difficult to remove food debris and plaque. There are two notable exceptions: early childhood decay in bottle-fed babies and root decay in older adults.

Baby-bottle decay usually occurs in the upper front teeth as a result of continuous feeding on sweet liquids, including milk, formula and fruit juice. Nighttime use of a bottle is the most dangerous because the sugars sit on the baby's teeth for an extended time. Tooth loss can result, causing spacing and development problems when the permanent teeth erupt.

"It's very nasty," says Cleveland dentist Matthew Mecini, D.D.S. "You don't see it too often, but when you do, it's severe. The amount of damage that can be done to children's teeth in a short time is amazing."

Root decay occurs on the exposed root surfaces of older adults whose gums have receded as a result of gum disease. Many types of medicines older people typically use decrease saliva production, which can aggravate the problem. Saliva is important in preventing tooth decay because it can wash away food particles and bacteria and help neutralize acids formed by bacteria in the mouth.

The first sign of a cavity forming may be a white spot that in time may turn brown. Most patients, however, remain unaware of the decay until it is well advanced. Common signs that people notice include sensitivity of the tooth when exposed to hot or cold and brief pain after eating a sugar-containing food.

The dentist can diagnose decay with x-rays or by probing the tooth with a sharp instrument. Decayed enamel or dentin will feel soft.

Healthy Habits to Help Prevent Cavities

See your dentist regularly. How often will depend on your particular needs. Your dentist can advise you.

Brush your teeth regularly to reduce plaque buildup. Brushing should last for about 2 to 3 minutes each time to make sure you're reaching all teeth surfaces. Even though there are many kinds of toothbrushes on the market, including electric and sonic models, any will do, says Susan Runner, D.D.S., chief of FDA's dental devices branch. "The most important thing about the brush is to use it and to have appropriate instruction from your dentist or hygienist on how to use it," she says. The American Dental Association recommends switching to a new brush every three to four months.

Use a fluoride-containing toothpaste. Check to make sure there is fluoride in the product, says Fred Hyman, D.D.S., a dental officer in FDA's Center for Drug Evaluation and Research, because not all toothpastes contain it. Three kinds of fluoride ingredients are allowed, based on their effectiveness and safety, according to FDA's final monograph on over-the-counter anticaries drug products, which took effect in spring 1997. They are sodium fluoride, sodium monofluorophosphate, and stannous fluoride. Toothpaste manufacturers sometimes combine fluoride with other ingredients that are said to reduce plaque and gingivitis (inflammation of the gums). Although FDA has approved one such product, Colgate's Total toothpaste, for helping to prevent cavities, plaque and gingivitis, FDA has not determined the effectiveness of many of the antiplaque and antigingivitis ingredients. Also, consumers should be wary of claims that a dental product can do more than simply reduce tooth decay because, based on current scientific knowledge, this is the only cavity-fighting labeling claim FDA allows.

Floss daily. Like toothbrushes, any kind will do, as long as you use it daily. Flossing helps reduce plaque buildup in areas the toothbrush can't get to.

Eat a variety of foods, but eat fewer foods containing sugars and starches between meals, according to the federal government's Dietary Guidelines for Americans. The guidelines say that the more often you eat foods with sugars and starches and the longer these foods stay in your mouth before you brush your teeth, the greater the risk for tooth decay. Consider sugarless candy and gums made with certain sugar alcohols because they may not promote tooth decay. FDA allows these kinds of foods to carry a health claim to this effect, if the foods meet certain criteria.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.