Sugar-Free Soda? It’s Still No Better for Your Teeth

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There's something of a war on diet soft drinks, coming from medical researchers. The newest scientific coffin nail comes from Australia, where researchers at the government-sponsored group The Oral Health CRC published a study suggesting that sugar-free drinks contribute to tooth erosion just as much as do sugary beverages.

In a test of the effects of 15 common soft drinks on 70 extracted human molars, researchers found no significant difference between the erosive potential of the sugar-free drinks and the ones containing sugar, because the chemicals in the former appear to rot your teeth.

Tooth decay happens when plaque sits on your teeth and exposes them to acids that destroy tooth enamel. Tooth erosion is a different process and can occur in a few ways, but the biggest contributor is exposure to acidic food and drinks. The acids in what you eat and drink can dissolve the hard enamel on the tooth; in early stages it strips away layers of enamel and in later stages it can invade the pulp inside as well. Signs of tooth erosion include chalkiness, pitting, tooth sensitivity and "a scalloping of the occlusal (biting) surface of the teeth that in some cases can leave fillings exposed," the researchers wrote in their paper.


The introduction of sugar substitutes such as xylitol and sorbitol is credited with the reduction in tooth decay by many, so sugar-free drinks are touted for tooth-friendliness. Or they were, anyway. These findings are significant considering that more and more research supports the link between poor oral health and chronic inflammation suspected to contribute to deadly diseases, "including diabetes, cardiovascular diseases, kidney disease, respiratory diseases, inflammatory diseases, and some cancers," the researchers wrote in their paper.

Although they contain sugar, sports drinks are generally considered by consumers to be a healthier beverage choice, but they're not when it comes to tooth erosion risk — all but two of the eight drinks tested caused tooth-enamel erosion and softening. "Coca-Cola and the majority of the sports drinks caused enamel hardness to decrease by 30 percent to 50 percent," they wrote.

Another unfortunate finding was that in a taste test the researchers also conducted, the least erosive drinks were rated the least tasty. In their test of 32 sugar-free drinks, 22 had plaque pH levels below 4.5, making them significantly erosive. Drinks are considered acidic with pH levels below 5.5.

Unsurprisingly, they conclude their paper with a recommendation to limit your intake of diet drinks, sports drinks, juice, and soda and drink water instead. Also, don't brush your teeth right away after drinking any of the aforementioned, as brushing too soon can remove the softened enamel layer. It's better to rinse with water and wait an hour before brushing. Chewing sugar-free gum gets a thumb's up — it works up saliva that helps rinse away damaging acids.