Teeth and good dental health are things that people take for granted and don't think much about until a problem arises. The same can be said for eye sight. Many people don't get the routine eye exams until a problem arises.
The information and perspectives already provided are helpful. Here is some additional information that may be helpful to you:
Delta Dental published statistics that indicate that, of the 57% of Americans who have dental insurance, 81% saw the dentist twice a year, but only 34% of those without dental insurance did so. I know that I saw the dentist only when I really needed to (read: something hurt) when I didn't have dental insurance, but now that I have a job with dental insurance I go at least once a year for a checkup.
According to the CDC, the percentage of dental visits goes down as age goes up, but not by very much. As of 2009, 78% of children aged 2-17, 62% of adults aged 18-64, and 60% of adults aged 65 and up visited the dentist each year.