There is nothing worse than the pain of a toothache. The nerve in a tooth dying, an infection at the end of the root, or an infection from gum disease can be one of three causes of a severe toothache. In the first case there is almost never swelling; the second case sometimes swelling and in the last case swelling is almost always present. In the first two cases a root canal and crown are usually needed. In the last case the solution is more complicated and time consuming to diagnose and treat. It is very important to see a dentist as soon as possible. At home pain relief usually involves over the counter pain relievers.