Jan. 2 (HealthDay News) -- Other than at mealtimes, water is the only drink that should be used in toddler sippy cups, according to experts at the American Academy of Pediatric Dentistry (AAPD).

The reason: prolonged use of sugary drinks in sippy cups is a leading cause of pediatric tooth decay.

"Sippy cups were created to help children transition from a bottle to drinking from a regular cup, but they're too often used for convenience because they reduce spills. When kids sip sugared beverages for extended periods, they are exposed to a higher risk of (tooth) decay," Dr. Philip H. Hunke, AAPD president, said in a prepared statement.

Between 1988-1994 and 1999-2002, there was a 15.2 percent increase in cavities among kids aged 2 to 5 in the United States, according to the U.S. Centers for Disease Control and Prevention.

Research indicates that nearly one-third of toddlers with tooth decay problems used sippy cups, the AAPD noted.

The academy offered the following tips for parents:

• Sippy cups are meant to be transitional training tools to help children switch from bottles to cups. Sippy cups should not be used for extended periods of time.
• Unless it's being used at mealtime, a sippy cup should be filled only with water. Frequent drinking of any other liquid -- even if it's diluted -- from a bottle or a sippy cup should be avoided.
• Sippy cups shouldn't be used at bedtime or naptime unless they have only water in them.

"Keeping only water in the sippy cup outside of mealtime helps prevent against the development of unhealthy 'grazing' habits. It also helps guard against cavities," Hunke said.