You might think you're doing your teeth a service by drinking diet soft drink instead of full-sugar varieties, but a new study suggests diet soft drink can rot teeth as badly as cocaine or methamphetamines.
A US study compared a woman in her 30s who drank two litres of diet soda a day for up to five years, and found she had the same dental damage as a 50-year-old crack cocaine user and a 29-year-old methamphetamine user.
Drugs, such as crack cocaine and methamphetamine, contain acid and have also been linked with tooth decay.
"You look at it side-to-side with 'meth mouth' or 'coke mouth', it is startling to see the intensity and extent of damage more or less the same," said Dr Mohamed Bassiouny, a professor of restorative dentistry at the Temple University School of Dentistry in Philadelphia.
All three participants had to have their teeth extracted.
"None of the teeth affected by erosion were salvageable," Dr Bassiouny said.
The woman had turned to diet soft drink to prevent weight gain and because she thought it was the sugar in ordinary soft drinks that were damaging to teeth.
Dr Peter Alldritt, chairman of the Oral Health Committee told MSN NZ that it's the acid in diet and ordinary soft drinks that is so bad for our teeth.
"The acid causes the enamel to dissolve away," he said.
And the longer you sip on your soft drink, the worse the damage.
"If you open a can of soft drink and consume it in two minutes, you will have one huge acid attack on your teeth," Dr Alldritt said.
"But if you took the can and sat sipping it for four hours, that is more damaging because you are exposing your teeth to the acid for four hours."
If you've consumed an acidic drink — which includes soft drinks, white wine, sparkling wine, fruit juice or sports drink — you should wait at least 30 minutes before brushing your teeth.
"After you have had an acidic attack on the teeth, the enamel remains softer for 30 minutes and your toothbrush is going to damage the enamel," Dr Alldritt explained.
"Wait a minimum of 30 or 60 minutes. By this stage, the saliva helps to neutralise the acid and the enamel becomes harder. Swishing some water around your mouth is a better thing to do after drinking something acidic."
The American Beverage Association, which represents soft drink manufacturers, said regular brushing and flossing, as well as regular dentist check-ups, were the most important things for oral health.
"The woman referenced in this article did not receive dental health services for more than 20 years — two-thirds of her life," they wrote in a statement.
"The body of available science does not support that beverages are a unique factor in causing tooth decay or erosion."
But Dr Aldritt said that keeping diet and regular soft drinks as "sometimes" foods is a sensible idea to give you the best possible chance of avoiding tooth decay and erosion.