Your question shows concerns for radiation that most people share. However, to determine potential risk from any source of radiation there are several questions that we need to answer. First of all, what types and amounts of radiation are involved? What part of our body may be exposed and how? And lastly, how much radiation dose will we receive? After we answer these questions, we can gain some insight into possible consequences by comparison with other sources of radiation exposure.

To address your concerns for radiation from porcelain in dentures and crowns, we need to consider the type of radiation. The National Council on Radiation Protection and Measurements (NCRP) Report 95 indicates that porcelain dentures and crowns are made of feldspar materials that contain small quantities of radioactive potassium-40. In addition, beginning in the 1940s until the mid-1980s, the practice was also to add small amounts of uranium to give the dentures the natural color and fluorescence of real teeth. Uranium and its decay products of thorium and palladium are sources of alpha, beta, and gamma radiation. However, for several reasons discussed in Report 95, only the beta particles from uranium and potassium are likely to deposit any significant radiation dose to cells of the oral mucosa or skin inside the mouth.

Several studies in Report 95 show that for typical concentrations of uranium and potassium in porcelain dentures, the average beta dose to a person in the U.S. population is about 1.3 mSv a year to the basal mucosa or skin inside the mouth. The millisievert (mSv) is a measure of radiation energy deposited in tissues. For comparison, NCRP Report 116 recommends a skin dose limit of 50 mSv a year for members of the public. Thus, the radiation dose contribution from porcelain dentures is only a small fraction of the recommended limit. When the beta dose to skin in the mouth is adjusted to an equivalent whole-body dose and the proportional amount of skin irradiated, the number drops to 0.00013 mSv a year. This report further recommends that any corresponding whole-body dose of less than 0.01 mSv a year is considered a negligible risk. For comparison, a recent report (NCRP 160) shows an average person in the United States receives an equivalent whole-body radiation dose of 6.2 mSv a year from natural and man-made sources. All of the reported studies would seem to indicate that you do not need to remove or replace porcelain dentures or crowns. There are also no reports in the literature to indicate any cancer attributed to radiation from porcelain.

You also asked about measurements. The only accurate way to measure radioactivity in dentures or crowns would be to take a sample to a laboratory where the materials may have to be ground up or dissolved for analysis. This would be an expensive analysis and may not be warranted in light of the studies described above.

For more information on radiation from dentures, you may wish to consider the answer to Question #8152 on the HPS Web site Ask the Experts feature.

Helpful information on uranium in dentures is also provided on the Oak Ridge Associated Universities Web site .

Ray Johnson, MS, PE, FHPS

Certified Health Physicist

References

Available at www.ncrponline.org .

National Council on Radiation Protection and Measurements (NCRP) Report No. 95, “Radiation exposure of the U.S. population from consumer products and miscellaneous sources,” Bethesda, MD 1987

National Council on Radiation Protection and Measurements (NCRP) Report No. 116, “Limitations of exposure to ionizing radiation, “Bethesda, MD 1993