Why are dental xrays needed?

Dental xrays, or radiographs, serve to help the dentist diagnose a patient's oral health condition in areas he or she can't see clinically.  Most commonly, this involves using radiographs to diagnose cavities under old fillings or crowns and between our teeth in areas that can't be seen or even accessed with tiny instruments. Other reasons your dentist takes radiographs:

  • Periodontal disease
    • Bone levels, prognosis of individual teeth
  • Oral pathology
    • Cysts, tumors, bone health
  • Development
    • Impacted teeth, wisdom teeth, extra teeth, orthodontics
  • Anatomy
    • Prior to extractions, dentures, implants & surgeries
  • During and after dental treatment
    • Root canals, implants, crown & bridge, surgeries

What about dental xray radiation exposure?

The amount of radiation exposure from dental xrays is small compared to our daily exposures and very small compared to the levels necessary to cause damage. Sieverts (Sv), Grays (Gy), and Rads are units used to quantitate radiation. 1 Sv = 1 Gy = 100 rad = 100 rem.

1 Sv = 1000 mSv. The earliest symptoms of a full body exposure do not occur until 1-2 Gy or 1000-2000 mSv. Dental xrays are a localized radiation and lead aprons help to protect our bodies.

Exposure From Dental Xrays (mSv)


Risk of damage at

Full Mouth Series, D-speed film


Lens of Eye


0.06 mSv

0.08 mSv

Bone Marrow


0.09-0.15 mSv

0.17 mSv

Thyroid Gland


0.23 mSv

0.32 mSv

Digital Xrays

The introduction of digital xrays have also served to decrease radiation from dental xrays by up to 50% from conventional xrays. In fact, films faster than D-speed films used in the table above are now in use in many offices (including our office). E-speed films reduce radiation by up to 40% from D-speed films. F-speed films can reduce radiation by up to 25% from E-speed films.

Daily exposures:
Visit the American Cancer Society or the Environmental Protection Agency to learn more.

Radiation (ionizing radiation that can cause cancer) from daily exposures include: Cosmic, the earth's crust, radon, radiation therapy, xrays, CT scans, nuclear, consumer products (tobacco, building materials, food), airport scanners, UV: sunlight, tanning beds, welding torches. Note: non-ionizing radiation has not been established as being able to cause cancer.

Interesting numbers:

  • According to the EPA, the average yearly total exposure for an individual is 6.2 mSv. 3 mSv from natural sources alone.
  • Yearly exposure from cosmic radiation at sea level is 0.26 mSv. It is 0.50 mSv in Denver, the Mile High City. That means here in Hawaii we could get a full mouth series (16-18 xrays) and a panoramic xray every year and those in Denver would still receive more radiation from the elevation alone (cosmic radiation) (White and Pharoah, 2005).
  • The earth's crust exposes the Northeastern United States to 0.46 mSv per year while those along the Atlantic and Gulf receive 0.23 mSv per year.

Total radiation dosages (approximate):

  • A chest x-ray is about 0.17 mSv, Mammogram 0.7 mSv, Medical CT of the head is 2 mSv.
  • CBCT's Oral Surgeons use prior to surgeries such as implants are 0.005-0.04 mSv.
  • 4 bite-wing's at the dental office (F-speed) 0.04 mSv, full mouth series 0.17 mSv.