I will still have to choose against the toothache. A toothache is a constant pain that you often can't do anything about. At least with constipation, I can usually treat it.
Oh, I've been badly constipated before, for a few days without going, but not to the point of having to go to the emergency room, thankfully. Though medication-caused constipation is probably worse. For me I could never blame anything other than poor diet -_-
But of course both are bad. I just really hate toothaches...