Can tmj sometimes take a very long time to go - even with treatment - like three years?

You mean TMD?: Temporal mandibular joint dysfunction is often a life long condition that may or may not be progressive depending on factors unique to the individual. If you feel you have this condition, it is best to see a dentist who can diagnose and treat your symptoms.

TMJ is forever: Most medical professionals agree that there is not a 'cure' for temporal mandibular joint myofacial pain dysfunction syndrome (tmj or more accurately tmd). I tell my tmd patients (usually females) that tmd is episodic and we will 'minimize and manage' their symptoms. When stress exacerbates inactive tmd, i recommend my patients wear their tmd muscle relaxation splint every night for three weeks.

Unlikey but possible: If TMJ surgery and/or orthodontic movements are done to treat TMJ syndrome, yes it is possible for years of treatment. Most TMJ syndrome cases are resolved quickly by a specially designed night guard.. See your dentist!

Yes: TMJ often is a chronic condition. May wax and wane. But never "go away". Make sure you are being treated by a TMJ expert.