Unlike dental insurance, which may not cover preexisting conditions, you can shop for a discount dental plan knowing you need a root canal and select the plan that offers the cheapest price, says Buddy Johnson, chief executive officer of national discount dental provider DentalPlans.com. "You could sign up today and go to the dentist tomorrow," he says.

When a plan makes sense, when it doesn't

If you have insurance and know you'll need extensive work done in a given year and it will fall below your policy's spending caps, a discount dental plan might not make sense, says Mark A. Cesarano, a health and welfare consultant with the Philadelphia-based employee benefits firm the Savitz Organization.

But "if you've been on top of taking care of your teeth and you just want to have some protection for if the worst case happens, then a discount card can be something that works for you," Cesarano says.

And if you've already hit your insurance plan's coverage ceiling for the current year and would have to put off a procedure until next year to get coverage, or if your budget simply cannot bear the cost of insurance, a discount plan might be your best option. "Discount plans can be a big help in managing a more limited budget," says Evelyn F. Ireland, executive director of the National Association of Dental Plans.

As with any important financial decision, do your homework first. Find out what providers in your area are on the plan and what procedures are covered. Make sure that costs and benefits add up to a net plus for your particular situation.

What discount plans offer >>