Some sugar free drinks can still cause damage to teeth.
A sugar free label does not automatically make a drink tooth friendly. Many of the flavourings that are used to produce sugar free drinks actually create a very acidic product. This applies to many sugar free soft drinks and sports drinks, and was well demonstrated in a study carried out by the University of Melbourne.
While most of us know that sugar is bad for teeth, the link between sugar and tooth decay is not so widely understood. When we eat anything with sugar, the bacteria in our mouth consume that sugar and convert it into acid which then damages the teeth. For this reason any very acidic drink can on some levels be considered as simply skipping a few steps in the process.
Acidic drinks lead to weakening / softening of the outer layer of the tooth and a process called erosion, and over time this damage can be cumulative and if you are unfortunate enough to wear right through the outer layer of Enamel, the erosion can then progress very rapidly on the inner layers of our teeth which are structurally weaker.
There is no doubt that taking a “harm reduction” approach reducing the sugar content in our diet is a wise thing to do but please be very careful not to substitute acidic drinks in the place of sugary ones. The only completely safe drinks are milk and water.