Dental radiographs, commonly referred to as X-ray films, or informally, X-rays, are pictures of the teeth, bones, and surrounding soft tissues to screen for and help identify problems with the teeth, mouth, and jaw. X-ray pictures taken byX-ray machine can show cavities, cancerous or benign masses, hidden dental structures (such as wisdom teeth), and bone loss that cannot be seen during a visual examination.Dental X-rays may also be done as follow-up after dental treatments.
 
A radiographic image is formed by a controlled burst of X-ray radiation which penetrates oral structures at different levels, depending on varying anatomical densities, before striking the film or sensor. Teeth appear lighter because less radiation penetrates them to reach the film. Dental caries, tooth decay, infections and other changes in the bone density, and the periodontal ligament, appear darker because X-rays readily penetrate these less dense structures. Dental restorations (fillings, crowns) may appear lighter or darker, depending on the density of the material
 
The dosage of X-ray radiation received by a dental patient is typically small, equivalent to a few days' worth of background radiation environmental radiation exposure, or similar to the dose received during a cross-country airplane flight. Incidental exposure is further reduced by the use of a lead shield, lead apron, sometimes with a lead thyroid collar. Technician exposure is reduced by stepping out of the room, or behind adequate shielding material, when the X-ray source is activated.