Hi there,
I'd talk with my doctor if I were you.
Diuretics, especially prescription ones can work fine for edema when prescribed but a doc should really be the one to determine if that is what you have and then he or she will be the one to prescribe what you need.
OTC ones are okay, and like all meds OTC or Prescription should only be taken as directed. You mention joint pain, this can come from a number of things which require different meds.
Diuretics abuse or just over usage can over tax your kidneys, strain the heart, big dangerous factor is upsetting the bodies electrolytes, potassium level,which really can mess up your heart.
Please consult your doc ASAP, maybe even have a physical to determine for sure what is behind your joint pain and/or edema, then your doc can get you proper treatment.
Ignoring what your body needs can cause more damage than good. Also discuss this before your oral surgery, with the oral surgeon, there is no point of putting your health into jeapordy.
I wish you luck with all of this, please take care.

DE