It depends on your dentist, but the American Dental Association recommends these guidelines:
All new patients should have a complete set of X-rays.
If you don't have cavities, and you are a model patient - that is, you often brush your teeth and use dental floss - the dentist should do a posterior occlusal x-ray (ie posterior) every 2 to 3 years. Some dentists may recommend annual X-rays.
If you have tooth decay or other dental problems, you may need to have an x-ray every 6 to 18 months.
The ADA recommends that children and adolescents use more frequent X-rays.
