Sensitive teeth can be caused by numerous things, such as brushing too aggressively or hard, using a medium or hard brush or grinding your teeth, which are called bruxism, and it can also be caused by gum recession, gum disease or cavities.
To alleviate these sensitive teeth, for bruxism we have a nightguard made, which is a hard plastic. This will prevent your teeth from moving and getting more gum recession because it alleviates the stress being put on the teeth. Another thing that you can do is to change your toothpaste to a Sensodyne or a fluoride gel, usually prescribed by your dentist, and that will alleviate some of the sensitivity.
Furthermore, you can have crowns replaced if your crowns have leaking margins, or replace fillings if the filings are too old and, finally, have a gum rejuvenation or gum graft done by a specialist which will help relieve that sensitivity.