Bad Day At Chiang Mai Ram Hospital Dental Clinic

Sounds like a cracked molar, very common as you get older. Once the crack gets big enough the nerve will die and you'll need a root canal.

You don't do root canal if the nerve is dead. The purpose of the root canal is to kill all the nerve if it is not already.

Not 100% correct, the root canal also cleans out the nerve channel in the root to prevent regrowth and in the interests of hygene also, before the post is fitted. So yes, the primary purpose is to kill the nerve but there are other reasosn why it must be done.

Stops your tooth going black.