Tooth decay is on the rise among kids in the US, according to the largest government study of the nation's dental health in more than 25 years.
Sugary foods and drinks and nonfluoridated bottled water may be contributing to the tooth decay of young children, it suggests.
An estimated 28 percent of U.S. children ages 2 to 5 had a cavity in at least one baby tooth between 1999 and 2004. This compared to a 24 percent rate from 1988 to 1994.
But there was some good news: Older children have fewer cavities and adults have less periodontal disease than in the past, and more of the elderly are retaining their teeth.
"Overall, we can say that most Americans are noticing an improvement in their oral health," said the study's lead author, Dr. Bruce Dye a dentist and epidemiologist with the National Center for Health Statistics.
He cited several likely factors, including parents serving young children more prepackaged foods with high sugar content, more sugary juices and sodas and more bottled water, much of which is not treated with fluoride.
Many experts credit fluoridation of public water supplies with driving down tooth decay starting in the middle of the 20th century.
"One of the interesting paradoxes of this is that we've actually had expansion in community water fluoridation in the United States over this time period," Dye said in a telephone interview.
"However, we've also had tremendous growth in consumption of bottled water, probably the majority of which is not fluoridated."
Just 21 percent of children aged 6 to 11 had tooth decay during the 1999-2004 survey period, down from 25 percent a decade earlier, the survey found.
Among those aged 12 to 19, the rate fell to 59 percent from 68 percent.
Dye said it is not clear why tooth decay rose among the younger children but not among the older children.
Others experts agree diet is at least part of the explanation for the rising cavity rates.
"The same things contributing to the obesity epidemic can also contribute to tooth decay," said Dr. Gary Rozier, a dentist who teaches public health policy at the University of North Carolina.
Inadequate dental care may also play a role. Cavities in young children can form very quickly, and parents should begin bringing their children to the dentist at age 1, said Dr. Joel Berg, chairman of the University of Washington's Department of Pediatric Dentistry.
Parents also must help their young children brush properly. "Preschoolers don't have the dexterity to really clean their teeth," Berg said.
Baby teeth naturally fall out as children age, but dentists say untreated decay can spread and is too dangerous to go untreated.
Rotten baby teeth are treated with fillings or — if the decay is extensive — extraction. But baby teeth fill certain spaces in the mouth, so their early removal may lead to crowding when adult teeth come in.