If you’re getting dental implant work done, you may want to ask if they outsource to other countries. A KPHO investigation bought 13 crowns from labs in China, Thailand and the US. Ten of them came back positive for lead, with levels from 110 parts per million to 240 parts per million. The problem may be from the surface stain used to whiten and brighten the teeth. Throughout history, lead has been used in paints because it’s bright, cheap, and highly durable.