Will a dental fistula keep the infection from going systemic?

Not necessarily: A fistula is indication that the abscess is chronic and long overdue for treatment. The infection will fester without care and without notice may spread. Please see a dentist immediately.

Of course not: Fistula is a sign that there is chronic infection and your body is draining it out. Unlike some other types of infection, a chronic dental abscess will not get better on its own. See your dentist for diagnosis, x-ray and treatment. Good luck.