Many people opt for sugar-free drinks in order to spare their teeth from decay and damage. However, a new study by researchers from Melbourne University found that sugar-free drinks are equally harmful to teeth.

The researchers, led by professor Eric Reynolds from the Oral Health Cooperative Research Centre, investigated how 23 sugar-free drinks affected oral health and found that most of them caused the tooth's enamel (the outer layer) to soften by a whopping 30 to 50 percent. These drinks included soda, flavored juices and flavored mineral waters.

Just how do they cause this damage?

Plaque on teeth forms from the sugar people eat. Bacteria feed on this plaque and, as they do, an acid is produced that destroys teeth and causes decay. In the same way, sugar-free drinks containing acid cause damage to teeth by stripping off the enamel.

Continued consumption of these beverages can cause dental erosion to progress further, sometimes to the point of exposing a tooth's inner soft pulp. Reynolds blamed the citric acid or phosphoric acid content of such drinks for the dental erosion.

"Many people believe soft drinks labeled sugar-free are completely safe for teeth, but unfortunately we're finding these aren't much better than the sugar-filled versions because of their potential to cause erosion of dental enamel," said Reynolds.

Reynolds also said one in three children suffer from dental erosion.

"We've seen bad erosion in the teeth of children aged 2 to 3 years old, and signs of erosion in permanent teeth of older children," he noted, adding that if children will keep drinking these beverages, they "are likely to need extensive dental treatment by the time they reach their teens."

Sugar-free candies, particularly orange or lemon flavored ones, likewise contain acids from the flavoring and destroy the teeth in the same way.

Sports drinks are not off the hook, either. After investigating eight sports drinks, the researchers found that six of them "caused significant enamel surface loss and enamel surface softening," according to a briefing paper about the study.

Reynolds recommends a very simple way to avoid dental erosion: "To give your teeth, or your children's teeth, the best chance, water is always a better choice."

The study was published in the Australian Dental Journal.