Tooth fractured about 90% through at the gum line after I got hit by a car while biking.
It would be 'fine' (painful but just really sore like the rest of me) if I bit down on that tooth for a bit to fully seat it, but every time I talked, ate, or otherwise accidentally jostled it it would be like someone jabbed a red hot poker into my face - the crack went across the root and any bit of movement pulled on it.
It was a rough two weeks to get it looked at and a root canal done. I kept getting woken up by searing pain if I moved a bit during the night.