If there's an abscess, root canal treatment should resolve the problem. If not, a re-treatment of the root canal is possible or an apicoectomy in which they remove the tip of the infected root along with the infection in that area.
Referral to a specialist for the procedure may be necessary.
For an abscess going on 4 yrs, wouldn't associated bone loss perhaps dictate need for extraction?
Does root canal or apicoectomy resolve all such abscess cases?
It can. It depends on the extent of damage of the alveolar jaw bone at the time that treatment is rendered. Additionally, since its a front tooth, I would be more willing to take a risk to try to preserve the tooth for cosmetic reasons as well. If there is a fistula that allows the pus to drain, it can remain somewhat stable over long periods of time but if that fistula is blocked, it can result in rapid spread of infection elsewhere.