What information do annual x-rays provide to my dentist?

You generally can't: There are different x-rays. Some show cavities, some bone loss (gingivitis), some show head & neck cancer or your risk for stroke. Many cavities don't hurt, and only show up on x-ray films. Don't wait 'till it hurts, it may not, or by that time you may need root canal!

A lot of data : Annual bite-wing x-rays can reveal decay, bone loss, abnormal growth, detect the trend of your oral health, and more. The benefits far outweigh the minute radiation received, especially if it is digital (no film).

Lots: Dentists look for variation from normal anatomy, such as cavities between teeth, loss of bone height, abscesses, and many other problems. And at less radiation than a day in the sun.