If more then one tooth hurts when stimulated by cold it is highly unlikely that all of them need a root canal. You would need to see a dentist to evaluate the problem and she/he can then examine the tooth/teeth in question and determine the cause of the sensitivity. Once that has been established there are several different ways to treat the problem depending on the cause and severity. Root canal treatment is only one form of treatment that may/may not apply to your case.

Hamida Shirazy