Bitewing x-rays are recommended every 1-2 years, depending on a patient's need. These x-rays are needed to show the crowns of the top and bottom of the back teeth simultaneously, as well as being able to see areas in between the teeth that are not easily seen by looking into the mouth.
Full mouth series of x-rays are a complete set of dental x-rays showing every tooth and the mouth, including the root and structures surrounding those teeth. These x-rays are recommended every 3-5 years, depending on a patient's need.
Panoramic x-rays show the entire upper and lower jaw, including all of the teeth, and are able to show unerupted permanent teeth and wisdom teeth. These x-rays are commonly taken on patients needing braces or their wisdom teeth extracted. Similar to the full mouth series of x-rays, a panoramic x-ray is recommended every 3-5 years depending on a patient's need.
Periapical x-rays are taken when you have one specific tooth bothering you in order to try and find the problem and determine a solution. These are not only recommended but are necessary at any dental appointment you come to with any type of dental pain in order to fully diagnose the cause of your discomfort.