Dental radiographs, also referred to as x-rays, are pictures of the teeth, bones and surrounding tissues. Dentists use them to find out whether there are any changes or damage within these areas of the mouth. They can be used to see if there are any cavities in the teeth, if there is bone loss around the teeth, calculus build up under the gums and hidden wisdom teeth. Most importantly they can also show cancerous or benign masses in areas that can’t be viewed in a visual examination. Decay and gum diseases both initially build up in between the teeth and under the gums, this is why they are sometimes missed in a general examination and this is when x-rays become beneficial. When completing an oral examination it is vital to be able to get radiographic views of the dental and periodontal tissues.
It is also necessary to use dental x-rays during and after the completion of treatment and at follow up appointments to monitor healing.
An x-ray picture is formed by a controlled burst of x-ray radiation. Depending on whether the thickness and shape of the oral structures are soft (gums) or hard (tooth bone), the radiation passes through at different levels before hitting the film or digital sensor. The teeth on the x-ray sheet look lighter because less radiation passes through them in order to reach the film. Things such as dental caries, infections and other changes in bone density appear darker because the x-rays pass through these less dense structures easier. Depending on what material was used to form them, dental fillings and crowns sometimes appear lighter or darker.
At approximately 0.005 milli Sieverts (mSv), the dosage that patients requiring x-rays receive is very small. This is almost equivalent to what they’d receive in a day through background environmental radiation exposure. Sometimes patients wear a lead apron or thyroid collar, and this will reduce incidental exposure. Because the dentist and technician takes lots of x-rays a day, the radiation they are exposed to is reduced when they step out of the room or step behind adequate shielding material.
The x-ray film needs to be developed once it has been exposed to the radiation, so that the image can be produced on the film. The film is produced in the same way as a traditional photograph (in a dark room and put through a series of chemicals), however most dental surgeries have an automatic processor, or take their x-rays on a digital system. It can take up to 5 minutes to develop each film. If there are any mistakes made during the development of the x-ray it is not possible to rectify them and another x-ray needs to be taken.
There are now digital x-rays which replace the film with an electronic sensor. This prevents mistakes and problems with processing because the image is sent straight to a computer screen and these problems can be adjusted using the computer. As technology evolves these types of x-rays are becoming more widely used because they expose the patient to less radiation and save a lot of time. They are however, very costly and it has been found that they have poor resolution quality, however this is constantly being improved in modern sensors.