John Jansheski

Jansheski was just 21, with only a few years of community college under his belt, when his father asked him to take over a business his brother had abandoned with over $150,000 in debt. At the time, the company sold just one product—his dentist father's invention, the Dental Pik. Since then Dentek has become the top brand for dental picks and tongue cleaners. Jansheski attributes his success to intense focus on niche products—"the space between the teeth was the space where we could win," he jests—and niche customers: the less than 20 percent of Americans us who even bother to floss once a week. Today Jansheski splits his time between Knoxville and Miami's South Beach. Jansheski teaches entrepreneurship at the University of Tennessee.