PORTLAND, Ore. (AP) — Cavities and tooth decay are on the rise among Oregon schoolchildren, according to a new survey of nearly 4,000 elementary students.

The oral health survey was last conducted in 2002, and since then, Oregon’s scores have dropped in every area.

More than one in three Oregon children needed treatment for tooth decay, according to the survey, and the rates of children ages 6 to 8 with past or present decay in seven or more teeth increased during the past five years. More than one in four had not seen a dentist the previous year.

Among the 32 states that conduct similar dental surveys, Oregon ranks 25th, seventh from the bottom, in the percentage of children with untreated tooth decay. All neighboring states — Washington, California, Idaho and Alaska — show better results.

The survey looked at 3,865 first-, second- and third-graders in 73 Oregon public schools last spring. A dental hygienist checked each child’s mouth, and parents filled out a questionnaire about demographics, health insurance and frequency of dental visits. More than one in three of the children needed treatment the day the survey hygienist examined them.

Gordon Empey, the state dental health consultant and a co-author of the report, said it provides more evidence that “oral disease is a silent epidemic,” as the U.S. surgeon general concluded in a 2000 report.

“Oral diseases are progressive and cumulative and become more complex over time,” Empey said at a panel discussion on dental health this week sponsored by Oregon Health Forum. “They can affect our ability to eat the food we choose, how we look and how we communicate. These diseases can affect economic productivity and compromise our ability to work or attend school.”

Dental disease is higher among children in rural Oregon than in the Portland metro area. It’s also higher among those who lack dental insurance, the poor and minorities.

The urban-rural gap in dental care shows up especially in children with a need for emergency treatment of dental pain or infection. In the Portland metropolitan area, the survey found, 1 percent of children need such urgent care. Outside the metro area, it’s 6 percent.

The report made four recommendations:

Fluoridation of water supplies. Oregon ranks 48th — ahead of Hawaii and New Jersey — among states in the percentage of residents using fluoridated water. Most dental experts tout fluoridation as a safe, cheap and effective way of preventing tooth decay, but in Oregon a coalition of anti-government conservatives and environmental groups has blocked statewide fluoridation.

• Early prevention, beginning as soon as age 1.

• School-based fluoride supplements for children in communities without fluoridated water.

• A school-based dental sealant program.