Joshua Brown sits completely still, made comfortable by nitrous oxide and Novocain, while Richard Abrams carefully removes one of Joshua’s baby teeth. As the pediatric dentist gently pulls it out, the tooth splits, a tell-tale sign of severe decay.

Just before that, the 6-year-old Boulder, Colo., boy also had two cavities filled.

“I don’t give as many ‘Great job, good check-up’ pats on the back as I used to,” says Abrams, who practices dentistry in Longmont, Colo.

Joshua is among a rising number of young children and teens suffering from dental decay, some dentists say. They report filling more cavities, installing more crowns and pulling more baby teeth than in previous decades.

At the root of the problem, they say, are sugary foods and super-sized drinks that have become more accessible to children through school vending machines, juice boxes, quick stops and fast-food restaurants.

Also to blame are sugary drinks and foods marketed as “healthy,” such as sports drinks, clear drinks, fruit punches and trail mixes and increasingly busy schedules that have made dental maintenance a lower priority, they say.

“Every time you see a teenager driving, they have a Big Gulp in one hand,” Abrams says. “If a kid has money at lunch and he has a choice between sugar and what’s good for you, you know what he is going to choose.”

Tooth decay is the most common chronic childhood disease, according to the U.S. Surgeon General.

In the 1970s and ’80s, studies showed that tooth decay had decreased due to an increase in prevention methods. Although no recent studies have tracked the rate of tooth decay in children, anecdotal accounts from dentists nationwide suggest that tooth decay is on the increase, says Matt Messina, a dentist in Cleveland and a spokesman for the American Dental Assn.

Through the years, dentists have developed preventive treatments to combat tooth decay, including fluoride rinses and toothpaste, which harden enamel, making it more difficult for acid to wear down teeth; brushing to reduce plaque; flossing to reduce tooth decay between teeth; and the application of sealant, a plastic filling material that flows into and seals the crevices of molars, preventing acid from penetrating and causing deep cavities.

But those won’t stop tooth decay if kids sip sodas all day and fail to brush, dentists say.

Acid-containing foods, such as soft drinks and sour candies, are the most damaging, they say. And sipping sodas or other sugary drinks throughout the day instead of drinking with a meal is more harmful because it bathes teeth in sugar for long periods of time

“If your candy is already acidic, we have double the problem,” Messina says.

In addition, teenagers aren’t taking the time to brush or floss their teeth, Abrams says.

He also say parents wait too long before taking their children to the dentist for the first time. They should bring them at age 1 to catch decay early, he says.

The cost of children’s tooth decay can be substantial for parents. A procedure like Joshua’s, which included two fillings, a tooth extraction and nitrous oxide, runs about $400.

The good news is children with lots of cavities in their baby teeth won’t necessarily have lots of cavities as adults, Abrams says. They just need to change their habits.

The same formula that has been promoted for decades still holds: Eat fewer sugary foods, brush and floss on a regular basis and see a dentist twice a year. Those who have more decay might need to see a dentist more often.

Nancy Winegard watches as Dr. Richard Abrams fills her daughter's cavity. Winegard worries her daughter will continue to accumulate cavities because of her sweet tooth.

“It sounds like a broken record, but the old ways still work the best,” Messina says.