According to a survey by the American Academy of Cosmetic Dentistry (AACD), the most important thing people want to change about their smile is the whiteness of their teeth, and almost 100 percent of those surveyed believe a great smile is one of their most important "social assets." So it's no surprise that there's so many whitening products on the market today to do this. But brighter smiles have been desirable long before modern solutions were available, and making a homem