What are dental X-rays?

X-rays are an important diagnosing tool for oral disease. Watch as Dr. Maria Lopez Howell explains how your dentist uses your x-rays while planning your treatment.

Kimberly Harms
Many diseases of the oral cavity can't be seen when the dentist examines your mouth. Dental x-rays are images that can help the dentist see things the human eye can't detect such as tiny areas of decay between the teeth or below fillings; bone damage from an infection or cyst; bone loss from gum disease; developmental defects; some types of tumors; the effects of trauma; and the position of unerupted teeth in children and adults.
Todd A. Welch, DMD
X-rays are a form of electromagnetic radiation, just like light, except they just have a much shorter wave-length. X-rays are a form of "ionizing" radiation which basically means they can penetrate body tissues which is what generally prompts concern. However it is just this property which makes them important diagnostic tools.

They can penetrate soft tissues like skin and gums much more readily than hard tissues like bone and teeth causing different degrees of shadows. The shadows can be captured on film or digital receivers and are called radiographs (x-ray pictures). Because today's dental x-ray machines and image capturing techniques are so sensitive, the amount of radiation needed for diagnosis is negligible, almost next to nothing compared to what you get from every day background radiation.

First a little science: A millisievert (mSv), named after Dr. Rolf Sievert, famous for studying the biological effects of radiation, is the unit of measurement that allows for comparison of doses from different x-ray sources. We use this measurement to help determine what we call the effective dose (E), a way of calculating the safety factor of each x-ray exposure. Since we know our annual background exposure to natural x-radiation (all around us) is from 2 to 4.5 mSv, and more if you like to take airplane rides, we can then make a comparison to dental x-ray examinations.

Dental radiographs are completely safe; the average single digital periapical film (peri-around, apical-root end of a tooth) is equal to 1 microsievert (uSv) i.e. one thousandth of an mSv. For four bitewing radiographs, traditionally used to image the back teeth for decay (the little tabs you bite on are called bite-wings), the exposure is 4 uSv. The x-ray machines take images of only the necessary structures, so there is no scatter of the x-rays to other tissues. Your dentist may even take the precaution of making you wear a lead apron to shield the rest of your body.
Dental X-rays are a form of imaging test that dentists use to learn more about the health of your teeth. A dentist can discover a lot about your teeth and gums simply by examining them with the naked eye. However, dental problems such as tooth decay and infections can often only be properly diagnosed by looking beneath the surface. X-rays use small amounts of radiation to create images on film called radiographs. As X-rays pass through the mouth, they're absorbed by the tissue. Some tissue, as well as denser objects, absorbs more X-rays than others. Teeth appear in lighter shades on a radiograph, while cavities and tooth decay show up in darker patches. These images help dentists to identify problems with the teeth.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.