Which vitamins will help my teeth not be so sensitive?

None: There is no vitamin or herbal supplement that reduces tooth sensitivity. It's best to see a dentist to determine the cause as there are many. You can try using a toothpaste formulated to reduce sensitivity to see if that helps. If not you may have an problem with one or more of your teeth causing the sensitivity. If it does help then keep using it. Either way do see a dentist to make sure.

None I know: I have never heard of a vitamin supplement helping with tooth sensitivity. You really need to see a dentist to make sure it is not a cavity or gingival(gum) recession. Try sensodyne in the mean time. It can help.