There is no such thing as a minor surgery or a simple outpatient procedure. This is one if many ways that life without adrenals changes. A normal body uses cortisol to cope with the trauma that occurs to the body during these "easy" procedures.
Before you have dental or medical procedure, please understand how to increase your steroid coverage to keep yourself out of adrenal crisis.
Follow this link to very detailed information outlining how much steroid to take for different procedures and operations.
http://www.addisons.org.uk/comms/publications/surgicalguidelines-colour.pdf
