小K，他在这里，告诉我你有“PERIODONTAL DISEASE"

Anyone that has bone loss, has periodontal disease.  That is bacteria that has grown under the gum to the point is damaged the bone around the root of the teeth.  At some point (beyond mild, beyond moderate)  the bone loss allows for bacteria to invade the root itself , causing the nerve to die.  Then the bacteria uses the dead nerve for a food source and grows fast.  This causes swelling.

The doctor and the patient evaluates the whole mouth to determine what to do with this one tooth.   If there is severe overall damage then the individual tooth with swelling is often not worth saving.  If there is  only overall moderate damage then the individual tooth often is worth saving.   But expect cost !             EXpect root canal, crown, perio root plane, perio surgery, sythetic bone placement.
Often bone grafting and implant has become more predictable.

Forgive me if you already know this.  Your doctor may have already informed you.