Sugar-free drinks and lollies might limit the kilojoules but their acidic chemical mixtures can increase dental erosion, say experts.

Just because they're sugar-free doesn't mean soft drinks and lollies aren't damaging your teeth.

"Many people are not aware that while reducing your sugar intake does reduce your risk of dental decay, the chemical mix of acids in some foods and drinks can cause the equally damaging condition of dental erosion," says Professor Eric Reynolds.

He's chief executive of the University of Melbourne's Oral Health Cooperative Research Centre, which has released a briefing paper in response to justified concerns about obesity and the perception that if there's no sugar, it's safe for teeth.

"We are now seeing one in three children with dental erosion," he told AAP.

"It really appears it's becoming a bigger problem and that we are seeing more sugar-free products."

The researchers tested sugar-free confectionary and 23 different drinks, including soft drinks and sports drinks.

They found drinks containing acidic additives and with low pH levels cause measurable damage to dental enamel, even if sugar-free.

"Dental erosion occurs when acid dissolves the hard tissues of the tooth," Prof Reynolds said.

"In its early stages, erosion strips away the surface layers of tooth enamel.

"If it progresses to an advanced stage it can expose the soft pulp inside the tooth."

While sugar levels are shown on products, food acids are listed in their ingredient code.

"You have got to know that code 330 is citric acid and phosphoric acid is 338."

As a general rule, if sugar-free confectionery is mint-flavoured it tends to be neutral, but if really tangy it's likely to contain citric acid, he said.

PREVENTING DENTAL EROSION
* drink more water, preferably fluoridated
* after consuming acidic products, don't brush your teeth straight away as it can remove the softened tooth layer
* instead, rinse your mouth with water and wait an hour before brushing
* limit intake of soft drinks and sports drinks