`Most of these patients are shocked to learn that these drinks are essentially bathing their teeth with acid,` says Poonam Jain of the Southern Illinois University School of Dental Medicine, who led the study.

Damage caused to tooth enamel is irreversible, and without the protection of enamel, teeth become overly sensitive, prone to cavities, and more likely to decay, the journal General Dentistry reports.

Researchers examined the acidity levels in 13 sports and nine energy drinks. They found that the acidity levels can vary between beverages and flavours of the same brand, according to a Southern Illinois statement.

To test the effect of the acidity levels, researchers immersed samples of human tooth enamel in each beverage for 15 minutes, followed by immersion in artificial saliva for two hours. This cycle was repeated four times a day for five days, and the samples were stored in fresh artificial saliva at all other times.

`This type of testing simulates the same exposure that a large proportion of American teens and young adults are subjecting their teeth to on a regular basis when they drink one of these beverages every few hours,` says Jain, also director, Community and Preventive Dentistry Program at Illinois.

Researchers found that damage to enamel was evident after only five days of exposure to sports or energy drinks, although energy drinks showed a significantly greater potential to damage teeth than sports drinks. In fact, the authors found that energy drinks caused twice as much damage to teeth as sports drinks.

With a reported 30 to 50 percent of US teens consuming energy drinks, and as many as 62 percent consuming at least one sports drink per day, it is important to educate parents and young adults about the downside of these drinks.

`Teens regularly come into my office with these types of symptoms, but they don`t know why,` says Academy of General Dentistry spokeswoman Jennifer Bone.

Bone recommends that her patients minimise their intake of sports and energy drinks. She also advises them to chew sugar-free gum or rinse the mouth with water following consumption of the drinks.

`Both tactics increase saliva flow, which naturally helps to return the acidity levels in the mouth to normal,` says Bone.