If you think hip-hop stars like Flavor Flav started the craze of jewel-studded teeth, you'd be wrong. A new study shows that Native Americans were using sophisticated dentistry techniques to add bling to their smiles 2,500 years ago. These ancient people used notches, grooves, and semiprecious gems to beautify their teeth. According to the study, the dentistry was for purely cosmetic purposes. "They were not marks of social class," says José Concepción Jiménez, an anthropologist at Mexico's National Institute of Anthropology and History.