Dental X-rays

The first dental x-rays were taken in the late 1890s after radiography was first invented. Today, all dentists receive training in x-ray film interpretation as part of their education. The technology is very inexpensive compared to other imaging techniques, and the equipment is simple for dental staff to use safely and effectively. Oral x-rays are routinely used in dental care for patients of all ages to identify disease or damage and to plan treatment. They may be used for many purposes, including:

• Finding cavities
• Checking the location and angle of teeth that have not yet emerged
• Seeing how well teeth line up with each other
• Determining how teeth will be affected by braces
• Looking at tooth roots in preparation for a root canal
• Identifying areas of bone loss from gum disease
• Diagnosing tumors, cysts or other growths
• Looking for fractures in the jaw
• Planning oral surgery

Types of Dental X-rays Taken

There are several types of x-ray views taken in dentistry. Each one is used for a different purpose. Here’s how you can tell what type of x-ray your dentist is showing you during your consultation or yearly exam:

Periapical: This view shows the entire tooth from the exposed crown to the root along with the surrounding socket in great detail. It is a “close up” that only captures a few of your teeth at a time. This type of film is helpful in identifying problems that are hidden below the gums or in the bone. For example, your dentist might use a periapical x-ray to look at an abscess, a cyst or an impacted tooth.

Bitewing: This film shows the upper and lower molars on one side of your mouth in the same shot. It allows the dentist to evaluate how the teeth are aligned (an important factor in correcting bite problems). Bitewing x-rays are also used to find cavities or evaluate bone loss from periodontitis. This is one of the most commonly used oral x-ray views for standard patient care.

Occlusal: These films are used to look at the structures surrounding the visible teeth. You will see all your upper teeth or all your lower teeth on a single film with an occlusal x-ray. A dentist might use this type of film to locate molars that have not yet emerged or identify abnormal growths in the jaw and gums. An oral surgeon might view an occlusal x-ray when planning cleft palate treatment or treating a jaw fracture.

Panoramic: This film is taken from the outside of your mouth. It shows all of your upper and lower teeth, your jaw, your nose and your sinuses. This type of x-ray can be used to look for problems like impacted teeth, tumors, jaw joint problems (TMJ), infection, fractures and other issues that may require surgical intervention. It’s not detailed enough to locate cavities. Not all dentists have the equipment to take this type of x-ray.

Other Types of Dental X-rays

Less common oral x-rays include:

Digital x-rays: This type of x-ray does not use film that goes through a traditional development process. Instead, the radiation passing through the mouth is captured by a sensor and fed into a computer to create an image of the teeth and jaw almost instantly. The image can be enlarged for better viewing. It can also be digitally enhanced to highlight small differences between the current set of digital x-rays and the patient’s previous set of digital x-rays. This can aid early identification of cavities and other developing dental health issues.

CT scans, tomography, cephalometric views and other types of x-rays: These may be ordered by specialists such as orthodontists, prosthodontists or oral and maxillofacial surgeons for advanced treatment planning. These various x-ray types provide either more detailed structural information or a broader look at how the various components of the face and teeth are related. Your specialist might need this information to plan orthodontics (braces), dental implants or tumor removal and reconstructive surgery. Typically, patients go to a hospital or imaging center rather than a dentist’s office for these images. The resulting information may be interpreted by an oral and maxillofacial radiologist in conjunction with your dentist.

Are Dental X-rays Safe?

Oral x-rays expose patients to very low levels of radiation. The modern equipment used, the lead shielding apron and color and the precautions dental staff takes during the procedure limits patient exposure as much as possible. Radiation from everyday sources is measured in very small units called millirems (mrems). A typical dental x-ray equals a dose of about two to three mrems. According to the National Council on Radiation Protection (NCRP), most people are exposed to about 360 mrems during a year from all sources in their environment (radioactive materials in the earth, cosmic radiation from outer space and trace amounts in food). A single dental x-ray equals represents less than one percent of your total annual exposure.

How Often Should You Get X-Rays?

This depends on your dental health history. One of the most common reasons for taking x-rays is to check for cavities. Adults who don’t have a history of cavities or a high risk of developing cavities are generally given bitewing x-rays every two to three years. Those with a known risk for cavities may get x-rays every 12 to 18 months. Teens and children usually have x-rays taken more frequently because their teeth are still developing and it’s imperative to catch decay early. However, if they don’t have any cavities, they probably won’t need bitewing x-rays more than once a year.

The other types of dental x-rays are ordered on a case-by-case basis. For example, a child’s wisdom teeth will generally be monitored starting at or before age 12 to decide when and if to perform an extraction. Patients with a history of periodontitis may have x-rays taken to determine whether they have bone loss and if it is getting worse. A toothache or any trauma to the teeth or jaw may mean you need to have films taken. If you are unsure why you need an x-ray, ask your dentist to explain what role the x-ray will play in your treatment plan.