回复：这颗牙做ROOT CANAL还是补牙

You can feel the "pain", this means the tooth is still alive. The routine is to take out all the decay and see how close it is to the nerve. If it's already into the nerve, you need a RCT (root canal treatment) right away. If it's just close but no exposure, then the tooth can be based and filled, with or without a crown depending how much tooth structure is missing. Watch closely, a RCT is indicated if it does bother you later.

Good luck.