"Fluoride makes the entire tooth structure more resistant to decay and promotes remineralization, which aids in repairing early decay before damage is even visible," said C.H. Chu, BDS, PhD, MAGD, ABGD, lead author of the study. "Studies have confirmed the most effective source of fluoride to be water fluoridation."

More than 144 million United States residents in more than 10,000 communities drink fluoridated tap water, providing an automatic defense against the harmful ingredients that cause such a preventable oral health disease.

"Instead of drilling holes to fix cavities, dentists would rather educate the public on how to avoid developing tooth decay in the first place," said Cynthia Sherwood, DDS, FAGD, spokesperson for the AGD. "Drinking tap water to receive fluoride is safe, and it's easier on your wallet than going to the dentist for a filling."

The second-most effective source of fluoride is varnish. Varnish, applied quickly and easily by a dentist, is one of the most concentrated products available commercially. Varnishes that contain sodium fluoride adhere to tooth surfaces when saliva is present, providing an excellent fluoride treatment.

Keeping fluoride in the mouth enhances its ability to arrest demineralization and promote remineralization, and varnishes are better for this purpose than fluoridated drinking water or toothpaste. Fluoride varnishes are typically used for patients who don't receive enough fluoride from other sources.

"The bland flavor and simplicity of the varnish method also makes it well-tolerated by young children and special needs patients," Dr. Chu said.

Dr. Chu looked at the effectiveness of fluoride in specialty milk and salt products, toothpaste, mouthrinse and gum, but found that only the water fluoridation and varnish methods had the ability to reduce cavities by more than 30 percent.

Patients who suspect that they have a cavity should visit a general dentist right away.