What was old Man Barnett's trade? What did this mean? Chapter 11

He's kind of a dentist. Old Man Barnett is often in back 'jumping' teeth. He uses a hot wire and hammer to literally knock out the tooth so it jumps to the ground. One day an older man, named Mr. Lett, comes to have his tooth jumped. When Old Man Barnett tries to wrap the hot wire around Mr. Lett's tooth, Mr. Lett gets his tongue caught in it and bucks like a mule. Afterward, they end up in a big fight. It's the first time Little Tree see Old Man Barnett fail to jump a tooth.