Teeth undergo constant demineralization and remineralization. When the tooth surface dissolves, the ions in your saliva can restore the dissolved minerals (enamel is 96% apatite). Consuming acid damages teeth by skipping the bacteria step altogether. You are exposing teeth to acid directly through consumption.
For those whose vice is not sweets but acidic drinks (coffee, tea, wine, orange juice) use a straw. However, be careful that you do not swish it around in your mouth or sip through the straw onto your teeth. Researchers from Bristol University Dental School have shown that the increased velocity of these liquids hitting your teeth (if you were using a straw as opposed to sipping it) increases dissolution.
After consuming acidic drinks, rinse your mouth with tap water and wait thirty minutes. Jaeggi and Lussi found that immediately brushing your teeth after acidic drinks may erode your sensitive softened teeth, suggesting that it may be better to wait 30 minutes to an hour for your saliva to restore your enamel.
It is like what Sun Tzu said: Know your enemy. If your enemy is sugary sweets, brush your teeth- no problem. If your enemy is acidic drinks, drink water or chew sugar-free gum to increase saliva flow. Give your teeth a chance to build themselves up.
This advice may sound counter-intuitive but this makes sense once you know the difference in sugar vs. acid’s attack mechanisms. (ama-)Zing!