Dental xray in june, pet scan in july. abscessed tooth with still with no pain. should i have them biopsy while doing a root canal? i have fnhl.

Probably.: I'm concerned that the pet is positive and you are not experiencing pain. Although an abscess would be pet+, the lack of symptoms and your history of fnhl raise the possiblity that this could be fnhl.

Biopsy: You can do a biopsy by itself. Usually non-surgical root canal treatment does not involve cutting the gum. You can do both procedure in one setting.

Root canal first: The vast majority of these will heal with root canal alone. I wouldn't jump to a biopsy unless it persists for at least a few years after the root canal, and the size of the problem is increasing. Apicoectomy with the biopsy is an option.