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How do dental X-rays work?
When X-rays pass through your mouth during a dental exam, more X-rays are absorbed by the denser parts (such as teeth and bone) than by soft tissues (such as cheeks and gums) before striking the film. This creates an image called a radiograph. Teeth appear lighter because fewer X-rays penetrate to reach the film. Tooth decay, infections and signs of gum disease, including changes in the bone and ligaments holding teeth in place, appear darker because of more X-ray penetration. Dental restorations (fillings, crowns) may appear lighter or darker, depending on the type of material used for the restoration. The interpretation of these radiographs allows the dentist to safely and accurately detect hidden abnormalities.
How often should radiographs be taken?
How often X-rays (radiographs) should be taken depends on the patient's individual health needs. It is important to recognize that just as each patient is different form the next, so should the scheduling of X-ray exams be individualized for each patient. Your dentist will review your history, examine your mouth and then decide whether you need radiographs and what type. If you are a new patient, the dentist may recommend radiographs to determine the present status of the hidden areas of your mouth and to help analyze changes that may occur later. If you have had recent radiographs at your previous dentist, your new dentist may ask you to have the radiographs forwarded.
The schedule for needing radiographs at recall visits varies according to your age, risk for disease and signs and symptoms. Recent films may be needed to detect new cavities, or to determine the status of gum disease or for evaluation of growth and development. Children may need X-rays more often than adults. This is because their teeth and jaws are still developing and because their teeth are more likely to be affected by tooth decay than those of adults.
What are the benefits of a dental radiograph
examination?
Many diseases of the teeth and surrounding tissues cannot be seen when your dentist examines your mouth. An X-ray examination may reveal:
- small areas of decay between the teeth or below existing restorations (fillings);
- infections in the bone;
- periodontal (gum) disease;
- abscesses or cysts;
- developmental abnormalities;
- some types of tumors.
Finding and treating dental problems at an early stage can save time, money and unnecessary discomfort. It can detect damage to oral structures not visible during a regular exam. If you have a hidden tumor, radiographs may even help save your life.
How do dental X-rays compare to other
sources of radiation?
We are exposed to radiation every day from various sources, such as frequent airplane travel and high altitudes, minerals in the soil, and appliances in our homes (like smoke detectors and television screens).
Source |
Estimated
Exposure (mSV*) |
Dental
radiographs x
Bitewings (4 films)
Full-mouth series
(about 19 films)
|
0.038
0.150
|
Medical
radiographs x
Lower GI series
Upper GI series
Chest
|
4.060
2.440
0.080
|
| Average
radiation from outer space In
Denver, CO (per year) |
0.510 |
| Average
radiation in the U.S. from Natural
sources (per year) |
3.000 |
Source: Adapted from Frederiksen NL. X-Rays: What is the Risk? Texas Dental Journal. 1995;112(2):68-72.
*A millisievert (mSV) is a unit of measure that allows for some comparison between radiation sources that expose the entire body (such as natural background radiation) and those that only expose a portion of the body (such as radiographs).
What if I'm pregnant and need a dental radiograph examination?
A radiograph may be needed for dental treatment or a dental emergency that can’t wait until after the baby is born. Untreated dental infections can pose a risk to the fetus, and dental treatment may be necessary to maintain the health of the mother and child. Radiation from dental X-rays is extremely low. However, every precaution is taken to minimize radiation exposure. A leaded apron minimizes exposure to the abdomen and should be used when any dental radiograph is taken. A leaded thyroid collar can protect the thyroid from radiation, and should be used whenever possible. The use of a leaded thyroid collar is strongly recommended for women of childbearing age, pregnant women and children. Dental radiographs are not contraindicated if one is trying to become pregnant or is breast feeding.
Please note: The ADA does not provide specific answers
to individual questions about fees, dental problems, conditions, diagnoses,
treatments or proposed treatments, or requests for research. Information about
dental referrals, complaints and a variety of dental procedures may
be found here. You can also refer to our Frequently
Asked Questions page for answers to common questions.
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