I've had root canals and veneers on 4 of my teeth. 1 of them has always been a little touchy. now there is a little white bubble above it what is it?

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.

Infection: Appears that one of the root canaled teeth is failing. Please see your dentist or an endodontist for further evaluation.

Contact DDS: See your dentist or endodontist for a definitive diagnosis. An antibiotic may be helpful. but long term the problem may need to be addressed, with either an apico, retreatment of the root canal or extraction/implant if the tooth is deemed to be nonviable.

RCT failure??: White bubble?? If draining then, depending on location of the bubble, I'd look for failure of old root canal (RCT) to retreat or a possible root fx. Please have it evaluated by your dentist.