MELBOURNE, Nov. 30 (UPI) -- Sugar-free drinks and candy are traditionally believed to pose less of a danger to teeth, but a study conducted in Australia found they can cause tooth decay at levels similar to those made with sugar.
Tooth decay is caused by acids dissolving the hard tissues of teeth, starting with the surface layers of enamel. Bacteria in the mouth consume sugar or carbohydrates, producing the acids -- so eating or drinking foods with less sugar in them should reduce acid production.
A new University of Melbourne study compared different types of drinks, both with and without sugar, finding an insignificant difference in the measurable tooth decay they cause.
"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," said Dr. Eric Reynolds, a professor at the University of Melbourne and CEO of the Oral Health Cooperative Research Center, in a press release.
The researchers tested 23 types of drinks on 70 human molars, using a Knoop microhardness tester to monitor changes in enamel hardness on the teeth. Overall, the researchers found little difference between drinks with and without sugar, with water and milk-based drinks having the least detrimental effect on enamel. The majority of the drinks caused softening of dental enamel by between 30 and 50 percent.
The drinks were tested in two groups. First, researchers compared 15 drinks available in Australian schools. Among the drinks sold to students on campus, those with and without sugar, all were shown to cause tooth decay, with the exception of milk.
Next, researchers compared Coca-Cola, water and several types of sports drinks. Coca-Cola, by far, caused the most tooth decay, and water caused no decay. Gatorade, Powerade, and Staminade, in liquid and powder forms, all caused decay as well. The exceptions were Sukkie and Endura, which researchers reported have higher calcium content and caused no decay.
The researchers also tested sugar-free confections, including candy and baked goods, finding 20 of the 32 products in the study had levels of acidity similar to the sugar-free drinks. In the study, they call out fruit-flavored confections, especially lemon-flavored ones, as being among the most damaging.
Swapping out acidic drinks for water more often and paying more attention to ingredients -- citric and phosphoric acids are particularly indicative of risk for decay -- are the best ways to limit damage to teeth, researchers wrote in the study.