I was in the dentist’s chair last week for what should have been a quick fix: replace a cracked filling, in and out. But as the drill started, I realized something wasn’t right. I could feel everything. Even the air flow from the suction was causing pain. After a few painful seconds, I raised my hand and asked, “Is it true that redheads need more freezing?” My dentist paused, gave me a look, and said, “Actually… yeah, they often do.” I nodded. “Thought so. I’m bald now, but I was ...