On the use of radiography and radiation dose consideration in orthodontic treatment

Abstract

The aims of this thesis were to analyse the use of radiography and radiation risk associated with orthodontic treatment. Study I measured absorbed doses to radiosensitive organs in the head and neck in an anthropomorphic phantom head using thermo¬luminescent dosimeters (TLDs) from digital intra-oral and panoramic radiography. Effective doses were calculated. Study II retrospectively evaluated panoramic radiographs of children and adolescents to determine positioning errors and pathological findings. A web-based questionnaire in Study III queried orthodontists about their use of radiographic examinations. Study IV retrospectively analysed the radiographs used in orthodontic treatment at two specialist clinics. Results: The salivary glands and the oral mucosa received the highest absorbed doses in intra-oral full-mouth and panoramic radiography and effective doses were 15µSv and 1975µSv, respectively. Positioning errors were found in 96% of the panoramic radiographs, 24% of the errors may have influenced diagnostic accuracy. The number of pathologies and anomalies were 1,221 in 558 (43%) patients, mainly in tooth-bearing regions. Only 63 (5%) of the findings may have influenced treatment outcome. Questionnaire respondents stated that radiographic examinations were mainly used in treatment planning stage, the most common were panoramic radio¬graphs. Local radiographic guidelines were often applied while little need for national guidelines was expressed. Preliminary results confirmed the use of radiographs predominantly during treatment planning and estimated radiation risk was comparable to approximately a week of natural background radiation in Sweden. In summary, effective doses were higher than previously reported in panoramic radiographs. Positioning errors in panoramic radiographs were common. Pathologies or anomalies were mainly found in the dentoalveolar regions, indicating that the radiation field could be limited in panoramic radiography. Panoramic radiographs are frequently used in orthodontic treatment. Even though radiation risk at the individual level is low, the risk at the population level is not negligible.