Contrary to popular belief dental decay has been shown not to be related to the total amount of sugar eaten or how often you brush your teeth. Decay is related to the total length of time that sugar is present in the mouth. For example, standard ‘Polos’ eaten and spread throughout each day would rapidly decay the teeth because sugar is in the mouth for longer, compared to all the Polos being eaten in one go.
Drinks can be harmful in exactly the same way as food, and any drink containing sugar or acid consumed regularly will damage the teeth.
Chewing sugar free gum encourages saliva to be produced and is not harmful for teeth.
The many and varied modern diets can have an implication for oral health and facial aesthetics and I am happy to discuss this with you. I favour healthy eating the 5:2 way since there is much scientific evidence to suggest that this is an anti-ageing and achievable diet plan. This link provides a good summary.