Nationwide Survey of Dental Offices: Findings and Trends in Radiological Practice

Background: A nationwide survey of x-ray imaging practices was conducted during 2014–2015 of a representative sample of US dental offices to gather data regarding patient exam frequencies, indicators for radiation dosimetry and related imaging data, and the data were compared to similar studies conducted during 1993 and 1999. Purpose: The survey results are compared with prior surveys to observe trends in the state of dental x-ray practice, particularly with regard to the use of digital imaging technologies, including cone-beam computed tomography. A total of 199 dental offices were visited in 25 participating states, and comprehensive radiological data were gathered regarding intraoral, panoramic, and cone-beam CT imaging practices. Data were also gathered regarding pediatric x-ray imaging practices. State radiation control data registries of dental offices were combined with gathered survey data to infer total US annual exam and per-capita exam volumes for all three imaging modalities. The clinical applications of imaging modalities in dentistry are not studied in this paper. Results: The number of intraoral x-ray exams performed annually in the US increased from approximately 191 million exams during 1993 to 296 million exams in 2014–2015. The per-capita rate also increased from 74 to 93 exams per 100 persons during the same period. The annual number of panoramic exams more than doubled from 11 million in 1993 to 21 million in 2014–2015. An estimated 3.5 million CBCT exams were conducted in dental offices in the US during 2014–2015, including 1.1 million exams on children and adolescents. Radiation dose from intraoral imaging decreased notably between 1993 and the most recent study in 2014–2015, from 1.9 mGy to 0.9 mGy. Conclusion: The total US exam volume and per-capita exam rates for intraoral imaging have increased from 1993 to 1999; however, patient radiation dose (as measured by skin-entrance air kerma, Ka,e) decreased substantially. A major contributor to that observed reduction in radiation dose is the now-prevalent use of digital imaging methods for intraoral radiography.