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Dental X-rays / Radiographs

What are dental X-rays?

Panoramic dental X-ray for assessment of developmental status.

A panoramic radiograph allows the dentist to assess a patient’s growth and development status, check for missing or extra teeth, and evaluate the teeth and bones of the facial area for disease processes.

Dental X-rays (radiographs) are used by dental health professionals to evaluate hard tissue (teeth and bones) for signs of disease process or abnormalities.

The type of X-rays prescribed is determined by the type of information the dentist needs to evaluate a patient’s dental condition and plan any required treatment. X-ray imaging techniques that are commonly used in dentistry include bitewings; cephalometric X-rays (cephs); cone beam computed tomography (CBCT) scans; full mouth series of X-rays; occlusal X-rays; panoramic X-rays (pano films); and periapical X-rays.

Orthodontic tracings on a lateral cephalometric X-ray (radiograph).

A cephalometric radiograph is a type of X-ray image showing the bones of the skull, mandible, and cervical spine, as well as the teeth. The orthodontist measures the relative position and angles of certain bones, and of the teeth to determine the extent and type of orthodontic treatment needed by the patient. (Image courtesy Thomas J. Melcher, DDS, MS).

Radiographs are an essential diagnostic tool of dental professionals. Even with promising emerging technologies, there is little doubt X-ray technology will continue to be a primary means of identifying and recording problems for the foreseeable future.

Since dental benefits became available, there has been controversy about how often a patient should be evaluated with routine X-rays. Unfortunately, the decision is sometimes made on the basis of how often dental plans will pay for them, rather than how often the patient’s dental history (e.g. decayed, missing and filled teeth); clinical findings (chips, cracks, decay, gum disease, etc.); and ALARA (As Low As Reasonably Achievable) exposure principles suggest they should be prescribed. Dental plans typically base payment of benefits for X-rays on the annual needs of an average plan participant. However, some patients may require more frequent imaging, and some less than others, based on individual needs.

Your dentist is the best qualified individual to evaluate your dental condition and prescribe appropriate radiographs on an appropriate interval.

The process of taking dental X-rays

The following is the general process for bitewing and periapical X-rays:

  • The radiographic technician will place a lead apron around your upper body, and and a lead collar around your neck. This is done as a safety measure, to shield sensitive tissues (thyroid gland, etc.) that are not part of the tissue being examined against direct or reflected ionizing radiation from the X-ray imaging device. Although dental X-rays produce low levels of ionizing radiation, it’s good to be conservative with exposure.
  • A radiographic imaging film or digital imaging sensor will be placed in your mouth behind the tooth or teeth to be imaged, and you will be asked to bite gently on a stabilizing device that holds the imaging film or sensor in position. This can produce momentary discomfort that is typically minor.
  • The X-ray tubehead will be aligned with the imaging sensor or film near your cheek.
  • X-ray exposure is initiated when the technician presses a switch. The amount and duration of the exposure varies according to the type of radiograph that is being exposed, and the type of tissue that is being examined. Normally, the exposure is rapid, lasting only a fraction of a second.
  • The image will be processed, either by traditional film processing techniques, or with some type of digital scanner. Traditional film takes 5 to 10 minutes to process. Digital images may appear within seconds of exposure, depending on the type of digital equipment being used.
  • Your dentist will analyze your radiographs for any sign of abnormalities, and will include them as part of your diagnostic record.
  • Your dentist will make recommendations appropriate to the diagnostic findings.

Some advantages and benefits of dental X-rays

Dental radiographs provide diagnostic information that cannot currently be obtained by any other practical means. The dentist can tell if problems are arising in the tooth or bone, and can prescribe and perform effective treatment to solve any problem before it becomes more serious. It is generally believed that the risks of dental radiographs are exceedingly low compared to the benefits conferred by having them done.

Potential disadvantages and risks of dental X-rays

Dental radiographs have a cumulative effect on human tissues. Some tissues, such as glandular tissues (for example, thyroid, etc.), are more vulnerable than others to these effects. The effects, at high enough doses are harmful. The goal of dental radiography is to obtain the necessary diagnostic information, while keeping the exposure levels to the patient and staff As Low As Reasonably Achievable, also known as the ALARA principle. It is the consensus of radiation physicists, and radiologists alike that dental X-ray exposure is low enough not to be harmful, especially when high speed film, phosphor intensifying screens, proper collimation, lead shielding aprons, and digital radiography (where available) are used. However, it is important that all radiographic imaging follow ALARA principles.

Keep in mind that all living things are continually exposed to ionizing radiation (like the type in dental radiography) from a variety of sources, the most common of which is radon gas in the atmosphere. We are also continually exposed to radiation from the sun and space, as well as terrestrial sources like stone and building materials. A radioactive isotope of potassium is found in all living creatures.

For comparison purposes, consider the following: A full mouth series of dental X-rays using D-speed film imparts about the same exposure to X-rays as walking around in your normal environment for 7 days. Using F-speed film for the same imaging series cuts the exposure to a little over one day. Digital radiography sensors are so good at detecting X-rays and building a diagnostic image from them, that as little as a tenth of the dose required for X-ray imaging film may be used. With F-speed film, a typical 4-bitewing X-ray series is equal to about an hour-and-a-half of background radiation. A single periapical X-ray using F-speed film is about 20 minutes of background radiation equivalent. And a single digital radiograph may be a fraction of that.

Keep in mind that radiographs are often more suggestive of problems than they are conclusive. This is why effective oral diagnosis frequently requires several different diagnostic tools to be used.

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Author: Thomas J. Greany, D.D.S. / Editor: Ken Lambrecht

This page was last updated on February 19, 2018.

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