You shouldn't drink distilled water to long. It's good short term to draw out toxins because it's empty and it takes minerals out of your body, but you need to put minerals in it if you drink it regularly. You can buy liquid trace minerals and add them to it. NOW brand is inexpensive. Dasani H20 from Coke does that with a minuscule amount of minerals and charges a lot.

Your teeth could be sensitive from receeding gums with the nerves are exposed. The best thing to do is toughen up your gums by brushing them every time you brush and go around them regularly with a toothpick. If they bleed they're not tough enough. I have toothpicks everywhere and break them in half and go around my teeth/gums many times daily and my dentist can't believe how pink and strong my gums are.

If you are hard on them now they'll stop bleeding, hold your teeth in for a long time, and stop hurting. If you don't, germs get in the loose gums and you could lose your teeth to gingivitis.

Probably minerals.
There's no minerals in distilled water, which is why I don't drink it.

Teeth - never heard of that. Are you taking any oral chelation products??

If you want to add minerals to your diet start eating a bunch of celtic sea salt. Go with the light grey. You might want to put a pinch of that in your distilled water if you feel you need to for a while. But I haven't heard of distilled water causing teeth sensitivity. It's usually the other way around. The teeth sensitivity goes away with the distilled water. Might be something else and just coincidental.

Doc