Dental Radiography (X rays): Courtesy of the American
Dental Association
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| Frequently Asked Questions (FAQ) |
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.
For more information, visit www.ada.org |
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