• Show areas of decay that your dentist may not be able to see with just a visual examination, such as tiny pits of decay that might occur between teeth
• Find decay that is developing underneath an existing filling
• Find cracks or other damage in an existing filling
• Alert the dentist to possible bone loss associated with periodontal (gum) disease
• Reveal problems in the root canal, such as infection or death of the nerve
• Help your dentist plan, prepare and place tooth implants, orthodontic treatments, dentures or other dental work
• Reveal other abnormalities such as cysts, cancer and changes associated with metabolic and systemic diseases (such as Paget's disease and lymphoma)

For children radiographs are used to watch for decay and to monitor tooth growth and development.

Dentists will use periodic X-rays to see whether a space in the mouth to fit all the new teeth, whether primary teeth are being lost quickly enough to allow permanent teeth to erupt properly, whether extra (supernumerary) teeth are developing or whether any teeth are impacted (unable to emerge through the gums).

Often, major problems can be prevented by catching small developmental problems early and then making accommodations.