The entire dentition from root to crown can be visualized on a single x-ray film through pantomographic radiology. The National Radiological Protection Board of Great Britain has measured tissue doses from seven types of pantomographic equipment and compared them with doses from full-mouth series and bitewing films (Wall BF, et al: Br J Radiol 52:727-734, 1979). The results indicated the dose to the thyroid, for example, to be between .001 rad and .03 rad for pantomography, .001 to .002 rad for a full-mouth series, and .002 rad for two left and two right bitewing films. The authors judged the tissue doses to [cause] "little or no increase in risk of somatic injury to the patient, provided the technique is not used to excess." They recommended that such examination should not be performed without justification more often than once annually up to 8 to 16 years of age, or more often than once every three to five years thereafter. [The risk of cancers from the cumulative dose to the population, assuming no threshold, was not discussed.]
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