Regarding regular cleanings...those are usually fine...but if you need any sort of shots to numb up the area then I would skip it. I don't usually need the shots for a regular cleaning.

Root canals are the big no-no from what I have read and I have told my dentist that those will not be a possibility for me. As a result I have needed to have about 9 teeth pulled in the past year. Much better to pull them than risk spread with a root canal. I've had a bunch of bridge work done and for that they actually knock me out...I go to a sedation dentist and it has worked out wonderfully because I'm not aware of any discomfort or pain and they can get everything done in one visit vs multiple torture sessions.

However...while a cleaning is not usually something to worry about...if you are in the midst of a bad flare up I would probably reschedule the appointment. I know that when I am in a flare up it makes everything else more sensitive too...and I wouldn't want to put myself in a situation where something normally pretty safe could end up causing spread. Plus...sitting in that chair for a cleaning with an arm in a bad flare up...no thank you. At least...that's what I would do in your situation.