Your dad should be checked for a possible subdural hematoma (bleeding between the skull and the brain). Any fall hard enough to break a tooth in an elderly person could cause a concussion or a subdural. They just did a story recently on nPR about how even pretty mild bumps to the head, like hitting your head on a kitchen cabinet, can cause subdurals in the elderly. If they're quite large, they can be drained to relieve pressure on the brain.
