Dental Radiographs are commonly called x-rays. Dentists use radiographs for many reasons :
to find hidden dental structures, malignant or benign masses, bone loss, and cavities .
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, 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 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 .
Once photographic film has been exposed to X-ray radiation, it needs to be developed
traditionally using a process where the film is exposed to a series of chemicals in a dark room as the films are sensitive to normal light .
This can be a time-consuming process, and incorrect exposures or mistakes -
in the development process can necessitate retakes, exposing the patient to additional radiation .
Digital x-rays, which replace the film with an electronic sensor, address some of these issues
and are becoming widely used in dentistry as the technology evolves .
They may require less radiation and are processed much more quickly than conventional radiographic films
often instantly viewable on a computer .
However digital sensors are extremely costly and have historically had poor resolution
though this is much improved in modern sensors .
This preoperative photo of tooth #3, reveals no clinically apparent decay other than a small spot within the central fossa .
In fact, decay could not be detected with an explorer .
Radiographic evaluation, however, revealed an extensive region of demineralization-
within the dentin (arrows) of the mesial half of the tooth .
When a bur was used to remove the occlusal large hollow was found within the crown and-
it was discovered that a hole in the side of the tooth large enough to allow the tip of the explorer to pass was contiguous with this hollow .
After all of the decay had been removed, the pulp chamber had been exposed and most-
of the mesial half of the crown was either missing or poorly supported .
It is possible for both tooth decay and periodontal disease to be missed during a clinical exam
and radiographic evaluation of the dental and periodontal tissues is a critical segment of the comprehensive oral examination .
The photographic montage at right depicts a situation in which extensive decay-
had been overlooked by a number of dentists prior to radiographic evaluation .