Cold sensitivity can indicate several different conditions. Gum recession, tooth decay, clenching and grinding the teeth can all cause cold sensitivity. This should be evaluated by a dentist and is often treated by applying a desensitizer on an exposed root surface, placement of a filling in a decayed tooth or making a guard to protect the teeth at night. The good news is that cold sensitivity is usually reversible. Sensitivity that disappears quickly after the offending stimulus is removed has a better prognosis than sensitivity that lingers, which begins to indicate the nerve in a tooth may be irreversibly involved and in need of a root canal.