White Lightning Smiles, Atlanta

Seeking to provide customers the speedy brilliance of its name, White Lightning Smiles supplies teeth-whitening pens designed for at-home application. With a 20% hydrogen-peroxide formula, the company boasts an advantage over other pens, which typically use a concentration between 2% and 6%. Users brush the pen's tip—which contains about 30 applications or a month's supply—against their teeth after brushing and flossing, at which point the solution takes to polishing and scaring away stains in a 15-minute session.