What causes sensitive teeth?

Why can't a person see clearly underwater, what causes sensitive teeth, why do I wake up paralysed and can snail shells treat scars? Join Dr Chris for the answers to this week's crop of science questions as well as news of a breakthrough in immune suppression, a sugar-fuelled filter to remove chemicals from drinking water and why gossip affects the way you look at people... Like this podcast? Please help us by supporting the Naked Scientists