No dental insurance? Here is a possible solution:

MyWay (a news portal used by this editor) reports on Groupon and SocialLiving,  two pay for play franchises selling limited-time discounts on a variety of discretionary goods and services including restaurant meals, wine tastings, spa visits and hotel stays. Looks like they are about to enter the health care market, as well.

Here is how it works:  you buy a discounted service(s) from a dentist  (teeth cleaning and x-ray, for example), pay for the appointment up front (the full price) and cash in your discount via reimbursement from the franchises offering these deals.  Read the full MyWay article here. 

My research gave me the impression that LivingSocial was a more serviceable option of the two,  but it does not cost anything to do your own research.  With Groupon,  the site needs your zip code.  With LivingSocial,  you will add your city to the search request.  For me,  it was "livingsocialfresno."  Bot sites have free searches. 

Use these services at your own risk.