Fluoride isn't just for children.

"The use of fluoride can prove beneficial for both children and adults," says Sandra Burkett, D.D.S., instructor of clinical dentistry at the Columbia University College of Dental Medicine.

Twenty years ago, dentists thought that fluoride worked mainly by strengthening developing teeth before they entered the mouth. As a result, young children were the main focus of fluoridation efforts. Now, research has shown that fluoride applied to the teeth, using toothpastes, mouth rinses and fluoride treatments, is just as important for all teeth in fighting decay.

"The regular use of fluoride helps to protect the permanent teeth from decay and sensitivity, allowing patients to keep their permanent teeth much longer," Dr. Burkett says.

Although everyone should use fluoride every day, some adults are at higher risk of decay and might need more intensive supplementation. To find out if you might be one of them, consider these questions:

1. Are you taking any medications that cause your mouth to become dry? Do you have a disease that causes dry mouth? Many adults take medications that can cause dry mouth, called xerostomia. Many common medications have this side effect, including allergy medications, antihistamines, anti-anxiety drugs and high blood pressure medicines.

Some diseases, most notably Sjögren's syndrome and diabetes, also can cause dry mouth.

"Decreased saliva flow can increase your risk for dental decay," Dr. Burkett says. That's because saliva helps neutralize the acids in your mouth and washes away food particles that are fuel for decay-causing bacteria. Saliva also contains many minerals, including fluoride, that help keep your teeth decay-free.

If you are having dry mouth, try using a fluoride mouthwash to lubricate your mouth and protect your teeth. Saliva substitutes are also available at the pharmacy, and many people use them to replace the saliva they have lost.

Dr. Burkett also recommends sucking on sugar-free hard candy or chewing sugar-free gum to increase salivary flow. In particular, she recommends that you look for products that contain xylitol. "Xylitol is a naturally occurring and beneficial sugar," she says. "Also, brush regularly with fluoride toothpaste and visit your dentist as recommended to prevent the formation of cavities."

2. Have your gums receded so more of your teeth show, or has your dentist told you that you have periodontal (gum) disease? By the time you're an adult, you may already have some form of periodontal disease, which can cause your gums to recede and expose more of your teeth. This gives bacteria more room to roam and makes you particularly susceptible to cavities in the roots of your teeth. For example, more than half of adults over age 75 have had root decay. If your dentist has treated you for periodontal disease, your gums may have been reshaped and your tooth roots exposed. This also can lead to decay.

To protect your teeth's roots, your dentist can paint a fluoride varnish or gel on them. You can use a fluoride mouthwash or a prescription fluoride gel to get more fluoride.

3. Have you needed a filling in the last year? If you have had recent tooth decay, you're at risk for more. Having had a cavity in the near past means that you have the bacteria and other conditions necessary to form additional cavities. "The use of fluoride should be an important part of your daily oral health care regimen if you have prior cavities," Dr. Burkett says.

4. Do you have crowned teeth and/or bridges? Crowned teeth are not safe from cavities. As long as some natural tooth remains, these teeth are at risk. "The edges of fillings or crowns can provide a hiding place for decay-causing bacteria," Dr. Burkett says. "Fluoride can protect the tooth from decay and in certain cases stop the decay process and allow the tooth to get stronger."

5. Are you wearing dental braces? "Braces make it difficult for you to reach all areas of the teeth, and provide niches where food can become lodged. The plaque that forms as a result can lead to cavities," Dr. Burkett says. "Your dentist can recommend a fluoride rinse or gel that, when applied daily, protects the teeth against cavities."

6. Are you receiving, or have you received, radiation therapy to the head and neck? Adults receiving radiation therapy to the head and neck are at very high risk of tooth decay because the radiation damages their salivary glands, causing dry mouth. Saliva fights tooth decay, so people suffering from dry mouth are at higher risk for decay.

"If dry mouth results from radiation therapy, then it is important that you use generous amounts of fluoride to prevent decay and visit your dentist every two to three months, or as recommended," Dr. Burkett says.

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