One of the tenets of good dental health is obvious—Brush your teeth after every meal. This can help keep your mouth healthy throughout a long life. Another rule should be just as carefully observed: Do NOT use someone else's toothbrush. Sharing toothbrushes can shorten your life. Be safe, not sorry. But what about emergencies, when you have no other option than to borrow someone's toothbrush—just once? That's when this rule is [...]