Measurement of lifetime dental radiographic radiation exposure to the cranial meninges

Abstract

The overall goal of this investigation was to measure the ionizing radiation dose to the cranial meninges from a lifetime of self-reported dental radiography. The first aim was to estimate the radiation-absorbed dose to the cranial meninges from 1920 to 1993 for common dental intraoral radiographic techniques. Data for these estimations were derived from statistical models created from the published literature. Over these 73 years, the estimated dose to the pituitary gland showed almost 30 fold reductions from 9,000 to 342 microGray (mu Gy) for a full mouth survey, and proportionally similar reductions for 4 bitewings and single molar periapical film. The relatively high doses to the clivus region of the brain for multiple full mouth radiographs during the 1920's to 1960's was less but still similar in magnitude to radiation treatment for tinea capitus, which has been shown to be tumorigenic. The second aim was to determine the number of x-rays exposed on patients, using on-site abstracted records, claims data along with a survey of dentists self report. Results showed that, although the discrepancies between routine exposed and recorded x-rays are generally small (<10%), some procedures, such as root canal therapy and orthodontic treatment, expose substantially more x-rays on patients (2 to 3 times) than are recorded, stored or billed. The third aim was to determine the number of dentists visited over a subject's lifetime, not just those who were recalled. Using capture-recapture methods, with records retrieved from offices and subject recall, showed that 79% of all dentists visited were recalled, yielding a lifetime total of 6.5 dentists visited, on average. The fourth aim was to compare the recall of lifetime dental x-rays by the subjects with dental records, measure the accuracy and precision, and search for differential bias between cases and controls. Dental records available before the reference date (n = 298) were gathered for a subset of 74 of 200 cases and 84 of 400 controls. Compared to records, cases and controls over-reported bitewing (148%, 138%) and full mouth (144%, 129%) visits, and under-reported panoramic (59%, 80%) and cephalometric (17%, 50%) visits, respectively.