On the Road to Improving Traffic Safety

Dental cavities are one health problem that’s practically a rite of passage in the United States: Ninety-four percent of American adults who have any natural teeth have had at least one cavity in their lifetime. [1] At the same time, cavity control is one of the great public health success stories of the 20th century. The introduction of fluoride toothpaste, fluoridated community drinking water and new topical fluoride treatments like gels, foams and sealants have significantly reduced the prevalence of cavities, especially among children, in the past 50 years.

Despite the long history of fluoride treatment, questions remain about how well certain types of fluoride perform in comparison to others, how big of an effect fluoridation has had on adult cavities and whether fluoride is the best answer for “high-risk” groups that seem prone to cavities even in communities with fluoridated water.

Holes in the Evidence

In little more than a half-century, toothpaste with fluoride and fluoridated drinking water have made a significant impact on the prevalence of dental cavities in the United States. [13] Fluoride’s effect on cavity prevention is so well established that systematic reviews of the treatment may seem to underscore the obvious. But these reviews have also found gaps in what we know about fluoride’s benefits and risks.

For instance, most studies of fluoride treatment and cavity prevalence are done in children and adolescents, rarely adults. In part, the focus on children stems from the vulnerability of their “baby” teeth, which have weaker enamel than permanent teeth. Yet adults may adopt dietary habits or other health behaviors like smoking that pose their own special cavity risks. Older adults in particular undergo changes in the mouth that can boost the likelihood of cavities. As people age, they tend to produce less saliva and make take more medications that dry out the mouth as a side effect.

“Without the cleansing and shielding effects of saliva flow, tooth decay and other oral infections become much more common,” says Gretchen Gibson, D.D.S., M.P.H., of Veterans Affairs North Texas Health Care System.

Adults aren’t the only neglected group when it comes to fluoride studies. Despite improved dental care, a minority of children fall into a high-risk category for cavities, usually due to a combination of poor diet, improper or irregular toothbrushing or reduced access to regular dental care. A recent review by German researchers K.G. Konig and colleagues at Ernst Moritz Ardnt University suggests that “health promotion programs that are merely educational and do not provide fluoride do not seem to be effective” among these children. [14] But they note that there is a dearth of studies on different fluoridation strategies for high-risk groups.

Most of the fluoride studies analyzed in systematic reviews report only whether the treatment reduced the prevalence of cavities in a population. The reviews seldom include information on possible side effects and adverse effects of fluoride; in many cases the data are simply not collected. Fluorosis, or mottled tooth enamel caused by a fluoride overdose, is the most commonly reported side effect. Fluorosis is usually mentioned only in studies that examine multiple types of fluoride treatment.

Systematic reviews of fluoride treatment, like all health interventions, need to be updated continually with new data to maintain their usefulness. A growing concern for dentists, for instance, is the rising popularity of bottled water and home water filtration systems, both of which may lessen American fluoride consumption. [15] Will these new trends result in more cavities? New fluoride studies should help fill in this emerging gap in the evidence.

Gretchen Gibson, D.D.S., M.P.H.
Veterans Affairs North Texas Health Care System
(214) 857-1086
Gretchen.Gibson@med.va.gov

William Kohn, D.D.S.
Centers for Disease Control & Prevention
(770) 488-6071
wak8@cdc.gov

Amid Ismail, M.P.H., Dr.P.H.
University of Michigan
(734) 647-4182
ismailai@umich.edu

James Bader, D.D.S., M.P.H.
University of North Carolina, Chapel Hill
(919) 966-5727
jim_bader@unc.edu