Getting and keeping a beautiful smile can take work, but the people in these cities have no problem with that. So what does it take? According to Irwin Smigel, DDS., founder and president of the American Society for Dental Aesthetics (ASDA) and creator of Supersmile, there are a few key factors: Regular dentist visits, not smoking, keeping your soda, wine and coffee intake to a minimum, overall health, living in a humid enough climate (so your mouth doesn't dry out and allow bacteria to flourish), and brushing and flossing regularly (of course). All of these cities excel in these categories, so if you visit, prepare to be blinded by bright smiles.

While Portland is slacking a bit in dental visits (ranking no. 35*), it makes up for it with its low teeth loss (ranking no. 38*, with no. 1 being the worst/most teeth loss), lack of smoking (smoking can cause gum and tooth problems), and being in the top three of the cities that exercise the most. Overall health means your mouth will be in good shape, and exercise increases circulation to the gums. This plus Portland's high humidity (which keeps your mouth from drying out and breeding more bacteria), means residents' gums are in tip-top shape.

*According to the Centers for Disease Control and Prevention, Behavioral Risk Factor Surveillance System Survey Data, U.S. Department of Health and Human Services.

Philadelphia ranks pretty high in dentists per capita (coming in at no. 14, according to statehealthfacts.org), however it loses a couple marks for slightly below average dentist visits and teeth loss. What put Phillie on the list though, is its drink preferences. The city ranks no. 5 in least coffee consumption in 2007 and no. 1 in least cola consumption in 2007. Both of these drinks can cause major staining, so avoiding them means residents will have white teeth, even if they should visit the dentist more often.

According to WebMD, Lincoln is the nation's healthiest city, which means they'll have healthy gums and teeth as well. The state also ranks no. 11 in dentist visits and no. 13 in dentists per capita so residents are taking the necessary steps to keep their teeth looking good. The city's high humidity level also keeps mouths relatively germ-free.

Burlington has a few key factors working in its favor: it ranks no. 8 in smoke-free metro areas, plus it's no. 2 in fruit and vegetable consumption (and crunchy veggies can help clear plaque), no. 4 overall healthiest city, and no. 5 in most exercise. That plus their ranking of no. 14 in dentists per capita means there are a lot of healthy mouths in Burlington.