Dental X-rays

How do dental x-rays work?

Types of dental x-rays

A Policy for Our Patients

From The Explorer, the official journal of the National Association of Dental Assistants (August 1983)

"Mrs Andrews has read a lot about over exposure to radiation, and she refuses x-rays,
'That's all right, ' says the dentist ' We'll just have her sign a release.'"

It's not all right. Reason: patients can't legally consent to negligent treatment. Nor, in the view of courts, may patients take upon themselves the risks and consequences of negligent care. Unfortunately, the dental office would still be held legally responsible for failing to discover bone loss, fractures, etc. that only x-rays reveal. It hurts to turn a patient away, but unless Mrs. Andrews yields to the careful explanation of how lead shields and high speed film have slashed the exposure risk of dental x-rays, our office would probably be better off letting he r seek treatment elsewhere.

We seek to render the most professional care consistent with the "state of the art" as current standards apply to dentistry. We share your concern about x-rays and we take every precaution to minimize them. Among these safeguards:

• Every patient, male or female, old or young is draped with a lead radiation apron before any x-ray is taken.
• We try to postpone all x-rays with women who are or might conceivably be pregnant. The one exception is with absolute emergencies - and then only with the consent of her obstetrician.
• Only the highest speed films are used. Radiation is minimized because less time is required for exposure.
• Check up x-rays are taken only where indicated and under the following schedule:
  • 1. Decay prone or periodontal problems: Every 6 months.
    2. No new pathology for 18 months: Every 12 months.
    3. No new pathology for 36 months: Every 18 months.
    4. Full mouth survey: Every 5 years or as indicated.

There has never been a single instance reported in the dental or scientific literature of a patient contracting a malignancy because of dental x-rays.

The amount of radiation received from dental machines is as little as one twentieth of the power of a medical x-ray machine. Another major difference with dental x-rays is that there is literally no scatter x-rays - therefore a dental office wall does not have to be lead lined as a medical wall must be. Yet, the benefits to be derived from necessary dental x-rays are far greater than the hazards. If we missed finding a tumor which could destroy half a jaw bone or missed decay which could develop into a twelve hundred dollar root canal and crown treatment, would you feel that your refusal to have x-rays was realistic? Most people feel that such a real saving in health or economic costs is worth it. Remember also that the amount of radiation you receive from a session of dental x-rays is about the same that you would receive from the cosmic x-rays that you get during a flight at high altitude across the United States.

Radiation comes to us from natural sources too. We breathe radioactive radon in the atmosphere. We're exposed to cosmic radiation from space and terrestrial radiation from radioactive isotopes in stone and building materials. In addition to natural radiation we get radiation from tobacco smoke, watches with luminous dials, color television sets and computer screens.

A complete dental exam gives about one and half day's worth of radiation exposure.

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 on the radiograph. Teeth appear lighter because fewer X-rays penetrate to reach the film. Cavities and gum disease appear darker because of more X-ray penetration. The interpretation of these X-rays allows the dentist to safely and accurately detect hidden abnormalities.

Types of dental x-rays

Panoramic - Complete upper and lower jaw. Good for impacted teeth, eruption of permanent teeth, jaw fractures, tumors, cysts, etc. Not as good as full series for the details of individual teeth.

In this panoramic x-ray of a 7 year old the forming permanent teeth can be viewed. The light gray on the extreme right and left is the spine.

In this example of a panoramic the developing wisdom teeth (3rd molars) can be observed in this 16 year old.

Other types - There are specialized films taken for surgery, orthodontics and implant placement.

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